Content:
Presentation type:
ST – Solar-Terrestrial Sciences

EGU24-3620 | Orals | ST1.14 | Highlight | Hannes Alfvén Medal Lecture

Multiscale matters: when coupling across multiple scales drives the dynamics of solar system plasmas 

Sandra Chapman

The sun, solar wind and magnetospheres exhibit non-linear processes that can couple across a broad range of space and time scales. These multiscale processes can be central to the dynamics of far from equilibrium plasmas, where collisionless processes dominate. This talk offers highlights from two interconnected approaches to advancing our understanding of multi-scale processes in solar system plasmas.

From the plasma physics: If sufficient simplifications can be made, we can study the plasma dynamics from first principles. The non-linear scattering and acceleration of energetic particles in current sheets, by wave particle interactions, and in shocks, can be approached from non self-consistent single particle dynamics allowing the full non-linear physics, including low-dimensional chaos, to be considered. The physics of shocks, reconnection, and its interplay with turbulence can be approached by fully kinetic self-consistent simulations, albeit with restrictions on physical dimension and the range of scales resolved. If bursty energy and momentum transport is an emergent process, then it can be captured by reduced models.

From the data: The full dynamics is revealed in all its richness in observations. A wealth of in-situ and remote observations are available from the fastest physical timescales of interest to across multiple solar cycles. In principle, these afford the study of specific physical process such as reconnection and turbulence, and system-scale processes such as the dynamics of magnetospheres, all of which are fully multiscale and non-linear. In practice, determining the physics from observations relies upon establishing robust, reproducible patterns and relationships from multipoint data in these inhomogeneously sampled, non time-stationary systems. As well as providing fundamental physical insights, these can deliver quantitative estimates of space weather risk.

How to cite: Chapman, S.: Multiscale matters: when coupling across multiple scales drives the dynamics of solar system plasmas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3620, https://doi.org/10.5194/egusphere-egu24-3620, 2024.

EGU24-13951 | ECS | Orals | ST1.14 | ST Division Outstanding Early Career Scientist Award Lecture

Analysing CME observations and simulations with multi-spacecraft techniques 

Erika Palmerio

Coronal mass ejections (CMEs) are humongous structures that permeate the heliosphere as they travel away from the Sun. Beginning their journey from a more-or-less localised region in the solar atmosphere, they expand to many times the size of the Sun through the corona, measure about 0.3 au in radial extent by the time they reach 1 au, and interact with the structured solar wind and other transients to form so-called merged interaction regions in the outer heliosphere. One of the most prominent challenges in heliophysics is the achievement of a complete understanding of the intrinsic structure and evolution of CMEs, in particular of their spatiotemporal variability, which in turn would allow more precise forecasts of their arrival time and space weather effects throughout the heliosphere. The most common methods to detect and analyse these behemoths of the solar system consist of remote-sensing observations, i.e. 2D images at various wavelengths, and in-situ measurements, i.e. 1D spacecraft trajectories through the structure. These data, however, are often insufficient to provide a comprehensive picture of a given event, due to the scarcity of available measurement points and the enormous scales involved. Some ways to circumvent these issues consist of taking advantage of multi-spacecraft observations of the same CME (usually at different heliolongitudes and/or radial distances) and to use simulations to complement the available measurements and/or to investigate the 3D structure of CMEs without constraints on the number of synthetic observers.

In this presentation, we will first provide a review of the advantages of multi-spacecraft observations of CMEs and how they have helped us build the overall picture of CME structure and evolution that forms our current understanding. We will then showcase examples of detailed CME studies, both in the observational and modelling regimes, that have been made possible due to the availability of multi-point measurements. These will include events observed remotely and/or in situ by the latest generation of heliophysics missions, i.e. Parker Solar Probe and Solar Orbiter. Finally, we will speculate on possible future avenues that are worthy of exploring to reach a deeper understanding of CMEs from their eruption throughout their heliospheric journey, especially in terms of novel space missions that may improve not only our knowledge from a fundamental physics standpoint, but also our prediction and forecasting capabilities.

How to cite: Palmerio, E.: Analysing CME observations and simulations with multi-spacecraft techniques, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13951, https://doi.org/10.5194/egusphere-egu24-13951, 2024.

ST1 – The Sun and Heliosphere

Solar flares are efficient accelerators of energetic particles, mainly electrons, which transport energy from reconnection site to the chromosphere. Energetic electrons are thermalized in the chromosphere and produce hard X-ray emission (HXR) following the thick-target bremsstrahlung mechanism. The thick-target model predicts that altitude of the HXR sources in the footpoints of solar flare decreases with increasing energy. The relation was registered for the solar flares observed with Yohkoh/HXT and RHESSI. In our research, we investigated the energy-altitude relation in flare footpoints in a group of strong (M and X GOES class) events that showed emission up to 84 keV recorded by the Spectrometer/Telescope for Imaging X-rays (STIX) onboard the Solar Orbiter. Here we present the results of analysis of the relation, e.g. temporal evolution and density distributions on selected examples. One of the interesting effects visible in some cases is bump in higher energies, when the sources appeared roughly on higher altitudes, which was very rare observed by previous X-ray instruments, but in STIX observations it’s very common. Thanks to unprecedented high temporal and spatial resolutions of STIX data, we can trace changes of plasma dynamics in footpoints like never before. 

How to cite: Mikula, K. and Mrozek, T.: Statistical studies of the energy-altitude relation in the footpoints of solar flares observed by STIX, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5659, https://doi.org/10.5194/egusphere-egu24-5659, 2024.

EGU24-6035 | ECS | Posters on site | ST1.2

Wave-Particle Interactions near Interplanetary Shocks: Solar Orbiter Observations 

Xingyu Li, Verena Heidrich-Meisner, Robert Wimmer-Schweingruber, Qiu-Gang Zong, Ling-Hua Wang, Liu Yang, and Lars Berger

The interaction between waves and particles plays a pivotal role in particle acceleration near interplanetary shocks. Previously, detailed investigations about these processes were limited due to data availability and coarse time resolution from interplanetary missions. However, recent observations from the Solar Orbiter mission, with its high-resolution capabilities, have shed new light on this topic. In this work, we conduct a comprehensive study of wave-particle interactions near interplanetary shocks, using four years of data obtained by the Energetic Particle Detector (EPD), Magnetometer (MAG), Radio and Plasma Wave Analyzer (RPW) and Solar Wind Analyzer (SWA) onboard the Solar Orbiter. We analyze the propagation and polarization properties of waves associated with shocks through wavelet analysis. In addition, we reconstruct the pitch angle distributions and gyrophase distributions of particles in the solar wind frame of reference. These reconstructions help us identify wave-particle interactions in the data and investigate the energy transport during these events. We report on results from this ongoing analysis. Our results advance the understanding of particle acceleration induced by waves near interplanetary shocks, highlighting the role of wave-particle interactions in dynamic processes occurring in the inner heliosphere.

How to cite: Li, X., Heidrich-Meisner, V., Wimmer-Schweingruber, R., Zong, Q.-G., Wang, L.-H., Yang, L., and Berger, L.: Wave-Particle Interactions near Interplanetary Shocks: Solar Orbiter Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6035, https://doi.org/10.5194/egusphere-egu24-6035, 2024.

EGU24-6670 | ECS | Posters virtual | ST1.2

An iterative algorithm for determining the temporal characteristics of solar X-ray flares for the automated formation of a data set in machine learning systems 

Oleksandr Bilokon, Oleksiy Dudnik, Dmytro Chechotkin, and Ivan Denkov

Modern astronomical instruments and devices in space provide scientists with a wealth of scientific and technical information. Scientists and developers are confronted with the question of how to gather, process, and store data that defines a particular phenomenon while developing artificial intelligence systems. An extensive array of data processing techniques is also employed in X-ray astronomy; however, the efficacy of these techniques is not universally reliable, which has consequential implications for the overall functionality of artificial intelligence systems and the likelihood of accurate classification. Automation and manual processes constitute the two broad categories into which these methods can be categorized. Each of these categories possesses distinct merits and demerits. Simplyified metric selection and precise definition are factors that contribute to such errors. This study examines the process of determining temporal metrics for the automated creation of a data set using the light curves of solar X-ray flares. The acquired data is designed for eventual utilization in machine learning systems. In order to determine the temporal characteristics of a solar X-ray flare, the flare's initiation, maximum, and termination points are postulated. The provided quantity of data points is adequate for ascertaining the X-ray burst's total duration, rise time, and decay time. Using an iterative algorithm, the authors suggest making it possible to automatically figure out the metrics related to the start, peak, and end of an X-ray flare. Researchers are testing the iterative algorithm on fake data made by the damped oscillations function, on fake periodograms that make the light curve more accurate, and on real data from solar X-ray bursts. This approach enables the automated extraction of temporal attributes of a solar X-ray burst for subsequent storage and aggregation as a database. It also facilitates further processing and utilization in the training of artificial intelligence systems.

This work is supported by the “long-term program of support of the Ukrainian research teams at the Polish Academy of Sciences carried out in collaboration with the U.S. National Academy of Sciences with the financial support of external partners.”

How to cite: Bilokon, O., Dudnik, O., Chechotkin, D., and Denkov, I.: An iterative algorithm for determining the temporal characteristics of solar X-ray flares for the automated formation of a data set in machine learning systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6670, https://doi.org/10.5194/egusphere-egu24-6670, 2024.

EGU24-6724 | Orals | ST1.2

Longitudinal Extent of 3He-rich Solar Energetic Particle Events near 1 AU 

George Ho, Glenn Mason, Athanasios Kouloumvakes, Robert Allen, Robert Wimmer-Schweingruber, and Javier Rodríguez-Pacheco

Ever since the first 3He-enhanced solar energetic particle (SEP) event was reported in the literature in 1970, the exact mechanism by which the isotope is enhanced orders of magnitude higher than its solar wind value remains unknown.  But the source, acceleration, and transport of SEP events can only be studied by multi-point simultaneous in-situ measurement within the heliosphere.  However, multi-spacecraft observations of 3He-rich solar energetic particle (SEP) event are scarce.  Further observations are much needed in order to understand and properly constrain the source and transport of the remarkable enriched 3He SEP event. In this paper, we report six 3He-rich SEP events that were detected by ACE, STEREO and Solar Orbiter near 1 au during Solar Orbiter’s aphelion pass at the end of 2022 and early 2023.  Many of these events were detected simultaneously by at least two or three spacecraft at up to ~40° longitudal separation, while some events were detected by only a single spacecraft even though an adjacent spacecraft was less than 20° away. These fortuitous multi-spacecraft observations of 3He-rich SEP events thus provide us observational constraint on the acceleration and propagation of this special class of SEP events. In addition, we will show in this paper how multi-spacecraft measurements could also be used to constraint the solar source region of 3He-rich SEP event.

How to cite: Ho, G., Mason, G., Kouloumvakes, A., Allen, R., Wimmer-Schweingruber, R., and Rodríguez-Pacheco, J.: Longitudinal Extent of 3He-rich Solar Energetic Particle Events near 1 AU, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6724, https://doi.org/10.5194/egusphere-egu24-6724, 2024.

EGU24-7975 | Orals | ST1.2 | Highlight

Solar Orbiter: Recent science highlights and mission status  

Daniel Mueller, Yannis Zouganelis, Anik De Groof, David Williams, Andrew Walsh, Miho Janvier, Teresa Nieves-Chinchilla, and David Lario

This contribution will summarise recent science highlights of the ESA/NASA Solar Orbiter mission and provide a mission status update. Solar Orbiter started its nominal mission phase in December 2021, with perihelia around 0.29 au occurring every six months. The ten instruments onboard provide high-resolution imaging and spectroscopy of the Sun and corona, as well as detailed in-situ measurements of the surrounding heliosphere. Together, these observations enable us to comprehensively study the Sun in unprecedented detail and determine the linkage between observed solar wind streams and their source regions on the Sun. Solar Orbiter’s science return is significantly enhanced by coordinated observations with other space missions, including Parker Solar Probe, SDO, SOHO, STEREO, Hinode and IRIS, as well as new ground-based telescopes like DKIST. Starting in 2025, Solar Orbiter’s highly elliptical orbit will get progressively more inclined to the ecliptic plane, which will enable the first detailed observations of the Sun’s unexplored polar regions.

How to cite: Mueller, D., Zouganelis, Y., De Groof, A., Williams, D., Walsh, A., Janvier, M., Nieves-Chinchilla, T., and Lario, D.: Solar Orbiter: Recent science highlights and mission status , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7975, https://doi.org/10.5194/egusphere-egu24-7975, 2024.

EGU24-8177 | ECS | Posters on site | ST1.2

Study of the Interplanetary Coronal Mass Ejection of November 3, 2021 

David Arrazola Pérez, Juan José Blanco Ávalos, and Miguel Ángel Hidalgo Moreno

Interplanetary coronal mass ejections (ICMEs) transport magnetized plasma from the Sun. Magnetic clouds (MC) are closed structures immersed within ICMEs and form large-scale magnetic flux ropes. Their evolution in the solar wind is linked to the interaction with the surrounding solar wind and the magnetic force. In addition, these structures play a fundamental role in the propagation of solar energetic particles and cosmic rays observed by analyzing the flux variations of these particle populations. On November 3, 2021, one of these structures was observed at different solar distances by instruments aboard Solar Orbiter (SO) and instruments in Earth orbit.

Magnetic clouds are closed structures immersed within interplanetary coronal mass ejections. These structures have an important effect on the propagation of solar energetic particles and cosmic rays that is observed as variations in the flux of these particle populations. The evolution of a MC observed on November 3, 2021, is analyzed using in situ observations made by Solar Orbiter (SO), at 0.84 AU, and ACE, at 1 AU, spacecrafts when they were aligned with the Sun. The magnetic configuration of the MC is described using a magnetic model by observing its evolution at both heliodistances and the effect on solar energetic particles and cosmic rays.

How to cite: Arrazola Pérez, D., Blanco Ávalos, J. J., and Hidalgo Moreno, M. Á.: Study of the Interplanetary Coronal Mass Ejection of November 3, 2021, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8177, https://doi.org/10.5194/egusphere-egu24-8177, 2024.

The shock waves, spatial regions with magnetic field perturbations and irregularities, and other phenomena characterizing the environment in the heliosphere can occur during enhanced solar activity. Clarifying the reasons for these events allows us to better understand the interconnection between processes on the Sun and interplanetary space.

In our study, which is based on the data processing from both SWA-PAS and MAG instruments we examine variations of the different parameters of the solar wind and interplanetary magnetic field derived as a result of in-situ measurements aboard the Solar Orbiter in the first half of 2023.

In the period selected both instruments detected the events with significant variations of the key parameters of the solar wind befriended by specific changes in the magnetic field components. We demonstrate the most outstanding examples of the SWA-PAS and MAG data analysis allowing the identification of the ICME, shock waves, CIR, magnetic clouds, magnetic flux ropes, magnetic holes, and other Heliospheric phenomena with confidence. The particular interest is in the selected simultaneous or serial registration events of the two or more mentioned phenomena presented.

This work is supported by the “Long-term program of support of the Ukrainian research teams at the Polish Academy of Sciences carried out in collaboration with the U.S. National Academy of Sciences with the financial support of external partners”.

How to cite: Yakovlev, O. and Dudnik, O.: Recognition of the solar activity manifestation in the interplanetary space at joint data analysis from SWA-PAS and MAG instruments of the Solar Orbiter mission., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8270, https://doi.org/10.5194/egusphere-egu24-8270, 2024.

EGU24-8631 | ECS | Orals | ST1.2

Investigation of solar flares showing quasi-periodicity based on STIX Quick-Look light curves 

Żaneta Szaforz, Tomasz Mrozek, and Michał Tomczak

The emission of radiation associated with the release of energy in solar flares is in many cases modulated according to a quasi-oscillatory pattern. This behavior is known as Quasi-Periodic Pulsations (QPPs). STIX instrument on board  Solar Orbiter offers new opportunities to study these types of phenomena. We reviewed Quick-Look light curves of the STIX instrument recorded from the beginning of the mission (April 14, 2020) to the end of March 202. 129 flares with the clearest pulses were selected, for which the periodicity analysis was carried out using the Lomb-Scargle periodogram and the autocorrelation method. It was found that 70% of those flares showed statistically significant oscillations. The observed periods ranged from 43 to 1355 s. It was found that longer periods occur less frequently than shorter ones. It has also been shown that there is a relationship between the period and the time interval in which the oscillations were observed.

How to cite: Szaforz, Ż., Mrozek, T., and Tomczak, M.: Investigation of solar flares showing quasi-periodicity based on STIX Quick-Look light curves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8631, https://doi.org/10.5194/egusphere-egu24-8631, 2024.

EGU24-9679 | Posters on site | ST1.2

Solar Orbiter charging effects on electron measurements via SPIS simulation. 

David Herčík, Stepan Stverak, Petr Hellinger, Lewis Gethyn, Georgios Nicolaou, and Christopher J. Owen

The ESA mission Solar Orbiter is providing, besides other observations, in-situ measurements of the solar wind plasma. The boom mounted electron analyser (SWA-EAS) acquires ambient as well as spacecraft produced (photo-, secondary-) electrons. To correctly interpret and derive the solar wind electron population, we need to understand the artificial populations, their production rate, energy distribution, and directional dependence on the ambient conditions for the given spacecraft geometry. In order to investigate the various electron populations in the spacecraft vicinity, we incorporate a numerical model of the Solar Orbiter spacecraft into the Spacecraft Plasma Interaction Software (SPIS). Hereby, we present preliminary results and challenges of such simulations and their interpretations. 

How to cite: Herčík, D., Stverak, S., Hellinger, P., Gethyn, L., Nicolaou, G., and Owen, C. J.: Solar Orbiter charging effects on electron measurements via SPIS simulation., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9679, https://doi.org/10.5194/egusphere-egu24-9679, 2024.

EGU24-11192 | Orals | ST1.2

Modelling Solar Energetic Particle event onsets in the turbulent heliosphere 

Timo Laitinen and Silvia Dalla

Solar Energetic Particles (SEPs), accelerated during solar eruptions, are observed using instruments onboard spacecraft in interplanetary space, at a large distance from their source. As SEPs propagate in the solar wind, they are guided by the interplanetary magnetic field (IMF), which consists of a large-scale Parker spiral magnetic field superposed by turbulent fluctuations. The turbulence causes the SEPs to scatter along the magnetic field lines, resulting in some cases in delayed arrival of SEPs to spacecraft in interplanetary space. It also gives rise to meandering of field lines, which helps to spread SEPs across heliolongitudes, and eventually results in diffusive cross-field propagation of the particles. To investigate how turbulence affects SEP propagation and arrival to observing spacecraft in different locations in the heliosphere, we have developed a novel analytical model of the IMF, where the Parker spiral is superposed with Fourier modes that represent the turbulence. Unlike any previous models, our description reproduces the observed geometry for the main mode of turbulence, the so-called 2D mode, with both the magnetic field disturbance vector and the wavenumber vector normal to the background Parker spiral field. We use 3D test particle simulations to study the propagation of energetic protons in our new turbulent IMF description. Particles are injected close to the Sun and observables derived at different radial distances and heliolongitudes, representing the locations of near-Earth spacecraft as well as locations accessible to Solar Orbiter and Parker Solar Probe. We compare the SEP onset times obtained from our simulations to those obtained with a 1D focused transport model. We find that the turbulence prolongs the field lines, and thus when particle are simulated in our new IMF model, the SEP intensity onsets are delayed compared to those obtained by using a 1D focused transport model. Further, we find that onset delay depends on the longitudinal separation of the SEP source and the heliolongitude of the location where the observables are derived. We discuss the implications of our findings on current understanding of the sources and transport of SEPs.

How to cite: Laitinen, T. and Dalla, S.: Modelling Solar Energetic Particle event onsets in the turbulent heliosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11192, https://doi.org/10.5194/egusphere-egu24-11192, 2024.

EGU24-11461 | ECS | Orals | ST1.2 | Highlight

Solar Orbiter: Mission Goals, Recent Discoveries, and Future Outlook 

Yeimy Rivera

ESA’s Solar Orbiter mission, launched in February 2020, is designed to investigate how the Sun creates and controls the Heliosphere, and why solar activity changes with time. To achieve its objectives, Solar Orbiter is equipped with a comprehensive suite of remote sensing and in situ instruments that work in concert to connect coronal structures and phenomena to their heliospheric counterparts. It aims to advance our understanding of the solar dynamo, responsible for the Sun’s magnetic cycle, by venturing out of the ecliptic plane to directly observe the Sun’s polar regions, providing an unprecedented view of our star. Since its launch, Solar Orbiter has completed 5 perihelion passes below the orbit of Mercury where it has taken the most detailed images of the Sun to date. The high resolution images have revealed previously unresolved coronal features that deepen our knowledge of how the corona is heated and the solar wind is formed, as well as how eruptions are triggered and release energy. As we now enter farther into solar maximum, the mission is perfectly placed to gain fresh insight to how transients drive heliospheric variability and impact local space weather. As such, the talk will present a brief overview of the overarching Solar Orbiter science objectives, discuss recent discoveries by the mission, and outlook for future observations and its exciting journey out of the ecliptic plane.

How to cite: Rivera, Y.: Solar Orbiter: Mission Goals, Recent Discoveries, and Future Outlook, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11461, https://doi.org/10.5194/egusphere-egu24-11461, 2024.

EGU24-11872 | ECS | Orals | ST1.2

Linking Solar Flare Observations to a Series of Impulsive Solar Energetic Particle Events Measured with Solar Orbiter at 0.5 AU 

Mario Roco, Nils P. Janitzek, Lars Berger, Patrick Kühl, Verena Heidrich-Meisner, Daniel Pacheco, Alexander Kollhoff, Glenn M. Mason, George C. Ho, Javier Rodríguez-Pacheco, Raúl Gómez-Herrero, Laura Rodríguez-García, Luoise Harra, Krzysztof Barczynski, Andrew P. Walsh, Yannis Zouganelis, David Berghmans, Sam Krucker, Andrea Francesco Battaglia, and Robert F. Wimmer-Schweingruber

Impulsive solar energetic particle (SEP) events are typically associated with solar flares but the related particle injection and acceleration processes are still not well understood. We use in-situ and remote-sensing data from Solar Orbiter to establish a plausible link between a series of eruptions in a flaring region and a sequence of four SEP events measured at 0.5 AU between 5 and 6 March 2022. The direct comparison between these four events from the same source region allows to study the variability of the injected SEPs during an extended period of magnetic connectivity between Solar Orbiter and the flaring active region. In this study we analyze energetic electron, proton, and heavy ion data provided by the Energetic Particle Detector (EPD) suite onboard Solar Orbiter. Via a velocity dispersion analysis (VDA) of all measured particle species we estimate the solar event onset times which coincide with a series of solar eruptions that is observed by the Extreme Ultraviolet Imager (EUI) and the Spectrometer Telescope for Imaging X-rays (STIX) onboard Solar Orbiter. Further high-time-resolution EUV images and photospheric magnetic field information of the related active region is given by the Atmospheric Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory. Solar Orbiter and Earth were nearly perfectly radially aligned at this time which enabled this additional remote sensing by SDO. We find that the energy spectra of the heavy ion in-situ measurements show significant differences between the four investigated SEP events in terms of overall particle intensity, spectral slope, and 3He / 4He abundances. By comparison with the remote-sensing observations we find that the two stronger SEP events (with higher 3He / 4He ratios) are related to solar eruptions with a more complex eruption pattern leading to extended brightening and restructuring of coronal loop structures. These new detailed observations can be used as starting point for quantitative modelling of flare-associated energetic particle acceleration and release in active regions.

This work has been funded by the Spanish Ministerio de Ciencia, Innovación y Universidades project PID2019-104863RBI00/AEI/10.13039/501100011033.

How to cite: Roco, M., P. Janitzek, N., Berger, L., Kühl, P., Heidrich-Meisner, V., Pacheco, D., Kollhoff, A., M. Mason, G., C. Ho, G., Rodríguez-Pacheco, J., Gómez-Herrero, R., Rodríguez-García, L., Harra, L., Barczynski, K., P. Walsh, A., Zouganelis, Y., Berghmans, D., Krucker, S., Francesco Battaglia, A., and F. Wimmer-Schweingruber, R.: Linking Solar Flare Observations to a Series of Impulsive Solar Energetic Particle Events Measured with Solar Orbiter at 0.5 AU, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11872, https://doi.org/10.5194/egusphere-egu24-11872, 2024.

EGU24-11967 | ECS | Posters on site | ST1.2

Identifying the origins of magnetic field reversals: in-situ measurements from Solar Orbiter and connection to remote-sensing observations from SDO 

Jesse Coburn, Stephanie Yardley, Ryan Dewey, Nawin Ngampoopun, Gabriel Suen, Daniel Verscharen, Christopher Owen, Domenico Trotta, Georgios Nicolaou, Yeimy Rivera, Stefano Livi, Sue Lepri, Jim Raines, Rossana De Marco, and Charalambos Ioannou

Magnetic field reversals, where the radial component of the heliospheric magnetic field changes direction, are frequently observed in the near-Sun region. Theory and numerical simulations regarding these reversals suggest that possible generation mechanisms include interchange reconnection in the solar corona, or solar wind expansion and turbulence. Magnetic field reversals thus provide information about both the solar corona and solar wind acceleration and propagation. Previous observations, including magnetic field structure, He2+- abundance, and the so-called patchy-ness are not conclusive in revealing their origin. In this presentation we discuss in situ observations of protons, electrons, He2+, and heavy ions from Solar Orbiter's Solar Wind Analyser instrument , together with the magnetic field from the MAG instrument, during a long-duration magnetic field reversal. We identify the origin of the reversal using the in situ heavy ion data, magnetic connectivity tools, and plasma emission measurements from the Solar Dynamic Observatory. In addition, we study kinetic properties of the electrons, protons and heavy ions, in order to provide readily employable observational tests to help discern the origin of the magnetic field reversals.

How to cite: Coburn, J., Yardley, S., Dewey, R., Ngampoopun, N., Suen, G., Verscharen, D., Owen, C., Trotta, D., Nicolaou, G., Rivera, Y., Livi, S., Lepri, S., Raines, J., De Marco, R., and Ioannou, C.: Identifying the origins of magnetic field reversals: in-situ measurements from Solar Orbiter and connection to remote-sensing observations from SDO, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11967, https://doi.org/10.5194/egusphere-egu24-11967, 2024.

EGU24-13328 | ECS | Orals | ST1.2

Inter-Calibration of Solar Orbiter’s Heavy Ion Sensor and Suprathermal Ion Spectrograph 

Benjamin Alterman, Robert Allen, Ryan Dewey, Stefano Livi, Jim Raines, Susan Lepri, Sarah Spitzer, Chris Bert, Christopher Owen, George Ho, Antoinette Galvin, Lynn Kistler, Frederic Allegrini, Keiichi Ogasawara, Peter Wurz, Mark Philips, Raffaella D'Amicis, Glen Mason, Robert F. Wimmer-Schweingruber, and Javier Rodriquez-Pacheco

The distribution of charged particles in the heliosphere covers more than 16 orders of magnitude in particle flux and more than 6 orders of magnitude in energy. While the majority of these particles are ionized hydrogen (protons) and fully ionized helium (alpha particles), heavier ions are also present. Because of the large parameter space that must be covered, different instruments are required and these instruments must be optimized to specific energy and particle flux ranges. They must also be designed to target specific ion species. To properly characterize the means by which different energy ranges are populated, the observations from these different instruments must be intercalibrated.

We present initial progress intercalibrating observations from Solar Orbiter’s Heavy Ion Sensor (HIS) and Suprathermal Ion Spectrograph (SIS). HIS is a heavy ion composition experiment that targets the solar wind through the low energy range of suprathermal energies with mass and charge state resolution. SIS covers the suprathermal and low range energetic particles with high mass resolution but without charge state resolution. Together, these two sensors cover heavy ion composition from solar wind to suprathermal energies. During advantageous conditions, proton distributions across both instruments are also available. Properly intercalibrated observations across these instruments enable studies of charged particle energization across the energy ranges, which is essential for characterizing a wide range of phenomena in heliosphere.

How to cite: Alterman, B., Allen, R., Dewey, R., Livi, S., Raines, J., Lepri, S., Spitzer, S., Bert, C., Owen, C., Ho, G., Galvin, A., Kistler, L., Allegrini, F., Ogasawara, K., Wurz, P., Philips, M., D'Amicis, R., Mason, G., Wimmer-Schweingruber, R. F., and Rodriquez-Pacheco, J.: Inter-Calibration of Solar Orbiter’s Heavy Ion Sensor and Suprathermal Ion Spectrograph, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13328, https://doi.org/10.5194/egusphere-egu24-13328, 2024.

EGU24-15888 | Orals | ST1.2

 STIX electron flux maps allow the quantitative determination of the number of accelerated electrons in solar flares 

michele piana, anna volpara, paolo massa, gordon emslie, sam krucker, and anna maria massone

This talk shows that imaging-spectroscopy analyses from data recorded by the Spectrometer/Telescope for Imaging X-rays (STIX) on-board Solar Orbiter allow to disentangle the two factors that determine the observed hard X-ray spectrum of a solar flare, i.e., the density of the accelerated electrons and the ambient target density. More specifically, we show, for the first time in a quantitative way, that in the case of some peculiar events characterized by a significant coronal emission, the number of non-thermal electrons accelerated by the flare is relatively small and that a high rate of such electrons is stopped before they can reach the chromosphere

How to cite: piana, M., volpara, A., massa, P., emslie, G., krucker, S., and massone, A. M.:  STIX electron flux maps allow the quantitative determination of the number of accelerated electrons in solar flares, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15888, https://doi.org/10.5194/egusphere-egu24-15888, 2024.

EGU24-16212 | Posters on site | ST1.2

Kinetic properties of proton and alpha beams in the Alfvénic wind observed by Solar Orbiter-PAS  

Rossana De Marco, Roberto Bruno, Raffaella D'Amicis, Denise Perrone, Maria Federica Marcucci, Daniele Telloni, Raffaele Marino, Luca Sorriso-Valvo, Vito Fortunato, Gennaro Mele, Francesco Monti, Andrei Fedorov, Philippe Louarn, Christopher J. Owen, and Stefano Livi

Ion velocity distribution functions in solar wind are often found to be non-Maxwellian. Streams of accelerated particles and temperature anisotropies are typical non-thermal features, whose origin is debated since the early years of in situ measurements. In order to disentangle the kinetic processes which may play a role in the generation of such distortions, particle double streams need to be identified and isolated. To this purpose, we have developed a numerical approach that leverages the clustering technique employed in machine learning. Here, we present the results obtained applying our technique to the ion distribution functions of a typical fast Alfvénic wind stream observed by Solar Orbiter-PAS in mid-September 2022, at a heliocentric distance of about 0.58 au. We could separate up to four ion families, namely proton core and beam and alpha core and beam. This allows us to characterize and compare their features, like the relative densities and temperatures. Differently from the better-known proton beam, alpha beam represents a relevant fraction of the alpha population, around 40%. Separating such a massive beam may shed new light on alpha kinetic features like the anomalous overheating mechanism. Moreover, the study of the velocity drift of the various ion populations indicates that both the alpha core and the alpha beam are sensitive to the Alfvénic fluctuations, and the surfing effect found in literature can be recovered only when considering the core and the beam as a single population.

The similarities between proton and alpha beams would suggest a common generation mechanism, apparently due to local physical conditions in the plasma.

 

 

How to cite: De Marco, R., Bruno, R., D'Amicis, R., Perrone, D., Marcucci, M. F., Telloni, D., Marino, R., Sorriso-Valvo, L., Fortunato, V., Mele, G., Monti, F., Fedorov, A., Louarn, P., Owen, C. J., and Livi, S.: Kinetic properties of proton and alpha beams in the Alfvénic wind observed by Solar Orbiter-PAS , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16212, https://doi.org/10.5194/egusphere-egu24-16212, 2024.

EGU24-16348 | ECS | Orals | ST1.2

Modeling the source temperature of fast and slow winds using a 16 moments multi-species model 

Paul Lomazzi, Simon Thomas, Alexis Rouillard, Nicolas Poirier, Victor Réville, Michael Lavarra, and Pierre-Louis Blelly

Understanding the general properties of the various solar winds requires an understanding of the phenomena at their source. The properties of the solar wind are influenced by the exchange of energy at the base of the solar corona. For example, the speed of the solar wind is strongly influenced by the level of heating below the sonic point. The heating that occurs in the collisional part of the atmosphere modifies the ionisation level of the heavy elements and therefore their charge state. This is why the charge state ratios of heavy ions measured in the solar wind are good parameters for distinguishing between fast and slow solar winds. In this study, we use the new Irap solar atmospheric model (ISAM) to study the level of ionisation of heavy ions transported in fast and slow solar winds. ISAM is a 16-moment multi-species model that self-consistently couples the transport equations for neutral and ionised particles (H, p, e, He, O and Mg) from the lower chromosphere through the solar corona to the solar wind. The lower corona is a region that is strongly coupled to the transition region by the downward heat flux.

By solving first for H, p and e, we recover the results of previous modelling showing that variations in the source temperature modify the pressure of the transition region which, in turn, modulates the mass flux of the solar wind. Using an ad-hoc heating function characterised by a scale height inversely proportional to the expansion factor of the magnetic field lines channelling the solar wind, we first recover the general properties of the fast and slow solar winds, as well as the known observation that the source temperature of the slow wind is higher than that of the fast wind. We then solve explicitly the ionisation processes and the coupled transport of oxygen with the major species (H, p, e) in order to isolate the different processes that contribute to the ionisation level of the heavy ions. We compare the results of our modelling with spectroscopic and in situ data. This work was funded by the ERC SLOW SOURCE - DLV - 819189.

How to cite: Lomazzi, P., Thomas, S., Rouillard, A., Poirier, N., Réville, V., Lavarra, M., and Blelly, P.-L.: Modeling the source temperature of fast and slow winds using a 16 moments multi-species model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16348, https://doi.org/10.5194/egusphere-egu24-16348, 2024.

EGU24-17889 | Orals | ST1.2

A catalogue of large solar energetic particle events observed by Solar Orbiter for the first ~ four years of measurements (2020–2023) 

Athanasios Papaioannou, Laura Rodríguez-García, Raul Gomez Herrero, Eleni Lavasa, Athanasios Kouloumvakos, George Vasalos, Alexander Warmuth, Ian G. Richardson, David Lario, Ioannis Zouganelis, Francisco Espinosa Lara, Ignacio Cernuda Cangas, Patrick Kuel, Frederic Schuller, Krzysztof Barczynski, Sebastian Fleth, Anastasios Anastasiadis, Andrew Walsh, Daniel Mueller, and Javier Rodriguez-Pacheco and the A Solar Orbiter Team

Solar Orbiter (SO) observations provide an unprecedented opportunity to study the evolution of solar energetic particle (SEP) events from different locations within the heliosphere. In this work, we have compiled a catalogue of SEP events based on observations of both electrons and protons from the High Energy Telescope (HET) of the Energetic Particle Detector (EPD) that occurred in 2020 to 2023 during the ascending phase of Solar Cycle 25. A scan of simultaneous So/HET intensity-time observations for ~10 MeV protons and near relativistic (~1 MeV) electrons has been performed. We have identified all enhancements observed above the background levels of these particular channels and surveyed available solar wind data by the SO/ Solar Wind Analyzer (SWA) and the SO/Magnetometer (MAG) during the identified events. Moreover, we employed Velocity Dispersion Analysis (VDA) for protons and electrons and Time-shifting Analysis (TSA) for electrons, alone, with the aim to infer the SEP release times at the Sun. Our resulting catalogue includes 75 SEP events. For each of these events (and for each species), we provide the onset and peak time, the peak flux value and fluence. We also identify the solar associations/sources for the SEP events, by comparing the inferred release times of the SEPs to the related light curves from the SO/Spectrometer/Telescope for Imaging X-rays (STIX), the standard flare list obtained from the GOES X-ray Sensor and their associated coronal mass ejections (CMEs). We find that a significant portion of all SEP events in our sample (48%; 36/75) reached 50 MeV for protons and thus are Space Weather relevant. Finally, a statistical analysis of our observations is presented. We have investigated correlations between peak particle fluxes (for protons and electrons) and event fluences, as well as peak particle fluxes (event fluences), flare magnitude and CME speed. We also calculate the connection angle to the apparent source and identify a subsample of the events that are better connected to the solar event. In addition, the e/p ratio is calculated and a division of the sample based on Fe-rich and 3He-rich events is discussed. 

Acknowledgement: Research leading to these results has received funding from the Horizon Europe programme project No 101135044 (SPEARHEAD).

How to cite: Papaioannou, A., Rodríguez-García, L., Gomez Herrero, R., Lavasa, E., Kouloumvakos, A., Vasalos, G., Warmuth, A., Richardson, I. G., Lario, D., Zouganelis, I., Espinosa Lara, F., Cernuda Cangas, I., Kuel, P., Schuller, F., Barczynski, K., Fleth, S., Anastasiadis, A., Walsh, A., Mueller, D., and Rodriguez-Pacheco, J. and the A Solar Orbiter Team: A catalogue of large solar energetic particle events observed by Solar Orbiter for the first ~ four years of measurements (2020–2023), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17889, https://doi.org/10.5194/egusphere-egu24-17889, 2024.

EGU24-18758 | Posters on site | ST1.2

Comparison of solar energetic particle observations from Solar Orbiter, near-Earth spacecraft and STEREO-A during Solar Orbiter's Earth gravity assist maneuver in November 2021 and its close encounter with STEREO-A in December 2022 

Alexander Kollhoff, Stefan Jense, Henrik Dröge, Patrick Kühl, Raúl Gómez Herrero, Javier R.-Pacheco, Robert F. Wimmer-Schweingruber, and Bernd Heber

On November 27, 2021, Solar Orbiter has performed a gravity assist maneuver at the Earth and in December 2022 Solar Orbiter and STEREO-A were separated by less than 0.2 au. The periods around these two events provide unique opportunities to compare Solar Energetic Particle (SEP) observations from Solar Orbiter with corresponding observations from near-Earth missions and STEREO-A. The proximity of the different spacecraft offers a useful opportunity to compare the calibrations of the various particle instruments of the different spacecraft. Furthermore, the unique constellations can be used to study small-scale changes in the density distributions of the SEPs.

We will present observations of near-relativistic electrons with energies from 50 keV to 400 keV as well as observations of protons with energies from 50 keV to 50 MeV. In particular, we use the period around the Earth gravity assist maneuver for a comparison of measurements from the Electron Proton Telescope (EPT) and the High Energy Telescope (HET) aboard Solar Orbiter with measurements from the Electron Proton and Alpha Monitor aboard the Advanced Composition Explorer (ACE), the 3DP instrument aboard Wind and the Electron Proton Helium Instrument (EPHIN) aboard SOHO. The period around the close encounter with STEREO-A is used for a comparison of EPT and HET observations with measurements from the High Energy Telescope (STA/HET) and the Solar Electron and Proton Telescope (SEPT) aboard the STEREO-A spacecraft. For both periods we discuss the instrument calibrations and possible physical explanations for differences in particle observations.

 

Funding: This work was supported by the German Space Agency (Deutsches Zentrum für Luft- und Raumfahrt, e.V., (DLR)) under grant number 50OT2002 and has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 101004159 (SERPENTINE).

 

How to cite: Kollhoff, A., Jense, S., Dröge, H., Kühl, P., Gómez Herrero, R., R.-Pacheco, J., Wimmer-Schweingruber, R. F., and Heber, B.: Comparison of solar energetic particle observations from Solar Orbiter, near-Earth spacecraft and STEREO-A during Solar Orbiter's Earth gravity assist maneuver in November 2021 and its close encounter with STEREO-A in December 2022, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18758, https://doi.org/10.5194/egusphere-egu24-18758, 2024.

EGU24-2175 | Orals | ST1.4

Hyper Boris integrators for particle-in-cell simulation 

Seiji Zenitani and Tsunehiko N Kato

We propose a family of numerical solvers for the nonrelativistic Newton-Lorentz equation in particle-in-cell (PIC) simulation. The new solvers extend a popular 4-step procedure, which has second-order accuracy in time, in several ways. First, we repeat the 4-step procedure n cycles, using an n-times smaller timestep (Delta_t/n). To speed up the calculation, we derive a polynomial formula for an arbitrary cycling number n, based on our earlier work (Zenitani & Kato 2020, Comput. Phys. Commun.). Second, prior to the 4-step procedure, we apply Boris-type gyrophase corrections to the electromagnetic field. In addition to the magnetic field, we amplify the electric field in an anisotropic manner to achieve higher-order (N=2,4,6... th order) accuracy. Finally, we construct a hybrid solver of the n-cycle solver and the Nth-order solver. We call it the hyper Boris solver. The (n,N) hyper Boris solver gives a numerical error of ~ (Delta_t/n)N at affordable computational cost.

How to cite: Zenitani, S. and Kato, T. N.: Hyper Boris integrators for particle-in-cell simulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2175, https://doi.org/10.5194/egusphere-egu24-2175, 2024.

EGU24-2303 | ECS | Orals | ST1.4

Solar granulation-generated chromospheric heating and plasma outflows in two-fluid magnetic arcade 

Mayank Kumar, Kris Murawski, Blazej Kuźma, Luis Kadowaki, Emilia Kilpua, Stephan Poedts, and Robertus Erdelyi

Context. The heating of the solar chromosphere, the associated plasma outflows, and the origin of the solar wind are key issues in heliophysics. In this paper, we provide a new perspective on their connection to the propagation and dissipation of waves generated by solar granulation.


Aims. The primary objective of this paper is to conduct 2.5-D numerical simulations of the partially ionized lower solar atmosphere, investigating the propagation and dissipation of granulation-generated waves in the context of plasma outflows and the related heating of the chromosphere, which is due to ion-neutral collisions.


Methods. We use the JOint ANalytical and Numerical Approach (JOANNA) code to solve the two-fluid model equations. We take into account partially ionized hydrogen plasma composed of ions (protons) and neutrals (H atoms), which are coupled via ion-neutral collisions. We focus on a quiet region of the solar chromosphere which is gravitationally stratified and magnetically constrained by an initially set magnetic Plasma flows and solar chromosphere heating arcade. Solar convection situated beneath the photosphere is the main source of these waves that are propagating through the simulated solar atmosphere.


Results. The numerical results obtained in our study reveal an important process in the lower solar atmosphere. The naturally evolving convection generates waves and a portion of the wave energy is dissipated due to ion-neutral collisions in the solar chromosphere. This dissipation of waves, in turn, leads to the release of thermal energy, resulting in the heating of the solar atmosphere. This phenomenon is also associated with upward-directed plasma flows, which may play a role in the formation of the solar wind. Furthermore, our analysis of the dominant wave periods in the various layers
of the solar atmosphere closely aligns with observational data from Wiśniewska et al. (2016) and Kayshap et al. (2018). This alignment underscores the crucial role ion-neutral collisions play in facilitating the energy release process, shedding light on the intricate dynamics of the solar atmosphere.


Conclusions. Based on our numerical simulations, we can draw the following conclusions: The dissipation of waves in the two-fluid plasma caused by ion-neutral collisions in the two-fluid plasma model leads to plasma outflows and increased heating in the chromosphere. These plasma outflows may play a role in the generation of the solar wind and the accompanying heating.

How to cite: Kumar, M., Murawski, K., Kuźma, B., Kadowaki, L., Kilpua, E., Poedts, S., and Erdelyi, R.: Solar granulation-generated chromospheric heating and plasma outflows in two-fluid magnetic arcade, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2303, https://doi.org/10.5194/egusphere-egu24-2303, 2024.

Modeling the three-dimensional (3D) magnetic fields of the solar active region in multiple layers is very important. The main approach is to extrapolate the magnetic field from magnetograms measured in the photosphere. A basic assumption of the modeling in the past several decades was to completely neglect all plasma effects and to perform the so-called force-free field (FFF) extrapolations. While the force-free assumption is well justified in the solar corona, it is not the case in the photosphere and chromosphere. A magneto-hydro-static (MHS) equilibrium which takes into account plasma forces, such as pressure gradient and gravitational force, is considered to be more appropriate to describe the lower atmosphere and has been developing rapidly during the past several years. In this talk, I am going to review various MHS modeling methods, including tests of these methods with known reference models and applications to real data. Recent developments of the MHS modeling will also be presented.

How to cite: Zhu, X.: On the current state of the development of the magneto-hydro-static extrapolation method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2367, https://doi.org/10.5194/egusphere-egu24-2367, 2024.

EGU24-3315 | Orals | ST1.4

A Clue to the Filamentary Nature of Solar Filaments 

Gwangson Choe, Minseon Lee, and Sibaek Yi

It is generally accepted that solar prominences, also known as filaments, are formed through thermal condensation instability from hot coronal plasmas. Within solar prominences (filaments), counter-streaming subscale flows are frequently observed. It is quite surprising that thermal instability in magnetized plasmas with such shear flows has never been earnestly studied despite extensive research on thermal instability in various astrophysical contexts. In this paper, we have investigated this unexplored territory of thermal instability and have unexpectedly gained hints on why solar filaments are filamentary.

We have performed linear stability analysis of magnetized plasmas with shear flows within the framework of magnetohydrodynamics (MHD), incorporating radiative cooling, phenomenological plasma heating, and anisotropic thermal conduction. Our approach formulates an eigenvalue problem, which we solve numerically to derive eigenfrequencies and eigenfunctions.

Our findings reveal that, for shear speeds less than the Alfven speed of the background plasma, the dominant mode corresponds to an isobaric thermal condensation mode. Most remarkably, the eigenfunctions associated with this mode display a distinctive, discrete structure resembling delta functions, especially when the shear velocity in the k-direction exceeds 10−5 of the Alfven speed. We identify that these delta function-like spikes coincide with the zeroes of the coefficients of the second-order derivative terms in the differential equation of the eigenvalue problem.

In contrast, for shear speeds exceeding the Alfven speed (a rare occurrence in reality), we observe an isentropic Kelvin-Helmholtz instability, incompatible with thermal condensation.

Our investigation underscores that any non-uniform velocity field with a magnitude surpassing 10−5 of the Alfven speed triggers the discrete eigenfunction characteristic of the condensation mode. Consequently, filamentary condensation at discrete layers or threads, emerges as a natural and universal process whenever thermal condensation instability arises in magnetized plasmas with shear flows.

How to cite: Choe, G., Lee, M., and Yi, S.: A Clue to the Filamentary Nature of Solar Filaments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3315, https://doi.org/10.5194/egusphere-egu24-3315, 2024.

EGU24-4321 | Posters on site | ST1.4

Spontaneous Generation of Alfven Waves by Bursty Interchange Magnetic Reconnection in the Solar Corona 

Liping Yang, Jiansen He, Xueshang Feng, Hui Li, Fan Guo, Hui Tian, and Fang Shen

Alfven waves contribute significantly to the solar coronal heating, the solar wind acceleration, as well as Alfv\'enic turbulence formation. As a universal process, magnetic reconnection has long been credited as a potentially crucial source of Alfven waves, but how magnetic reconnection trigger Alfven waves remains elusive. Here, with simulations of three-dimensional bursty interchange magnetic reconnection in the solar corona, for the first time, we find that Alfven waves are spontaneously excited in the reconnection sheet and propagate bi-directionally even along the unreconnected magnetic fields. The enhanced total pressure inherently carried by flux ropes gives kicks to the magnetic fields, and the nearly same propagation speed of the flux ropes and the kicks makes the kicks growing into the observed Alfven waves, which have large amplitudes and high frequencies, carrying substantial energy for heating the quiet corona and accelerating the solar wind. Our findings demonstrate that Alfven waves are natural products of three-dimensional intermittent magnetic reconnection, bringing its fundamental significance for energy release, transport, and conversion occurring in the plasma system.

How to cite: Yang, L., He, J., Feng, X., Li, H., Guo, F., Tian, H., and Shen, F.: Spontaneous Generation of Alfven Waves by Bursty Interchange Magnetic Reconnection in the Solar Corona, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4321, https://doi.org/10.5194/egusphere-egu24-4321, 2024.

EGU24-6152 | ECS | Orals | ST1.4

First Principle Description of Plasma Expansion using the Expanding Box Model. Implications for CGL Theory in the Solar Wind. 

Sebastian Echeverria Veas, Pablo Moya, Marian Lazar, Stefaan Poedts, and Felipe Asenjo

Multiscale modeling of expanding plasmas is crucial for understanding the dynamics and evolution of various astrophysical plasma systems. In this context, the Expanding Box Model (EBM) was used to add the expansion into the kinetic equations, allowing us to describe plasma physics in a new system of reference non-expanding and co-moving with the plasma. This system allows us to maintain a constant volume through non-inertial forces, and its interpretation is fundamental to describing plasma physics.

We have employed the EBM formalism to incorporate the expanding properties of the system into the plasma dynamics, which mainly affects transverse coordinates (i.e., y y/o z). Coordinate transformations were introduced within the co-moving frame system to obtain the modified Vlasov equation. Our main goal is to develop a plasma physics theory through a novel first principle description in the expanding frame, which is fundamentally based on the (collisionless) Vlasov equation for the evolution of the velocity distribution functions. Based on this, the expanding moments, such as the continuity, momentum, and energy equations, can then be derived, and an MHD model of the plasma expansion can be developed. Finally, coupling the obtained moments and Maxwell equations, a CGL-like plasma description is developed in the EB frame to study the evolution of macroscopic quantities (temperature, magnetic field, parallel beta, and anisotropy).

Our results show the expansion affecting the kinetic and fluid equations through non-inertial and fictitious forces in the transverse directions, which contain all the information related to the expansion. These are thus reflected by the equations derived for the expanding moments of the distribution function, including density, bulk (drift) velocity, and pressure (or temperature). Furthermore, we developed an ideal expanding-MHD model based on these modified moments, providing a new interpretation and comparison with the existing results when expansion is considered. The EBM modifies the conservative form of the two adiabatic invariants in the CGL approximation. Equations are solved for radially decreasing magnetic fields and density profiles to study the relations between plasma parallel beta and anisotropy within the expansion. 

How to cite: Echeverria Veas, S., Moya, P., Lazar, M., Poedts, S., and Asenjo, F.: First Principle Description of Plasma Expansion using the Expanding Box Model. Implications for CGL Theory in the Solar Wind., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6152, https://doi.org/10.5194/egusphere-egu24-6152, 2024.

EGU24-6557 | ECS | Orals | ST1.4

Overview of Ion-Driven Instabilities in the Inner Heliosphere 

Mihailo Martinović and Kristopher Klein

Linear theory is a well-established theoretical framework proven to accurately characterize instabilities in the solar wind weakly collisional plasma. We aim to describe the statistical properties of linear ion-driven instabilities between 0.3 and 1 au. We analyzed ∼1.5M proton and alpha particle Velocity Distribution Functions (VDFs) observed by Helios I & II, and ~5M VDFs observed by Wind, using Plasma in a Linear Uniform Magnetized Environment (PLUME) dispersion solver to calculate growth rate, frequency, wavevector, and the power emitted or absorbed by each VDF component. The descriptive statistical analysis shows that the stability of the solar wind is primarily determined by the collisional processing, rather than the distance from the Sun. We use this data set to train Stability Analysis Vitalizing Instability Classification (SAVIC) Machine Learning algorithm capable to classify the predicted unstable modes into physically meaningful “textbook” types. This method enables us to map the instability properties in multi-dimensional phase space. The proton-core-induced Ion Cyclotron (IC) mode dominates the collisionally young solar wind, while the alpha population plays more important role in the wave energy dynamics of the older wind. We also demonstrate that the proton beam population is not affected by the collisions and has the core-beam drift as the main source of free energy that determines its overall behavior in the solar wind. SAVIC code used here is publicly available for the community.

How to cite: Martinović, M. and Klein, K.: Overview of Ion-Driven Instabilities in the Inner Heliosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6557, https://doi.org/10.5194/egusphere-egu24-6557, 2024.

EGU24-6886 | Orals | ST1.4

Energy transfer of imbalanced Alfvénic turbulence in the heliosphere 

Liping Yang, Jiansen He, Daniel Verscharen, Hui Li, Trevor A. Bowen, Stuart D. Bale, Honghong Wu, Wenya Li, Ying Wang, Lei Zhang, Xueshang Feng, and Ziqi Wu

Imbalanced Alfvénic turbulence is a universal process playing a crucial role in energy transfer in space, astrophysical, and laboratory plasmas. A funda-
mental and long-lasting question about the imbalanced Alfvénic turbulence is how and through which mechanism the energy transfers between scales. Here, we show that the energy transfer of imbalanced Alfvénic turbulence is completed by coherent interactions between Alfvén waves and co-propagating anomalous fluctuations. These anomalous fluctuations are generated by nonlinear couplings instead of linear reflection. We also reveal that the energy transfer of the waves and the anomalous fluctuations is carried out mainly through local-scale and large-scale nonlinear interactions, respectively, responsible for their bifurcated power-law spectra. This work unveils the energy transfer physics of imbalanced Alfvénic turbulence, and advances the understanding of imbalanced Alfvénic turbulence observed by Parker Solar Probe in the inner heliosphere.

How to cite: Yang, L., He, J., Verscharen, D., Li, H., Bowen, T. A., Bale, S. D., Wu, H., Li, W., Wang, Y., Zhang, L., Feng, X., and Wu, Z.: Energy transfer of imbalanced Alfvénic turbulence in the heliosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6886, https://doi.org/10.5194/egusphere-egu24-6886, 2024.

EGU24-7061 | ECS | Posters virtual | ST1.4

Observational and Theoretical Study of Lower Hybrid Drift Waves 

Neetasha Arya and Amar Kakad

One of the most important diamagnetic current driven instability transverse to the magnetic field is lower hybrid drift instability (LHDI) which excites lower hybrid drift waves (LHDW). LHDI gives rise to anomalous resistivity which further leads to onset of magnetic reconnection. Because of its high anomalous collision frequency, LHDI enhances the rate of transverse diffusion. The lower hybrid frequency (LHF) ranges between electron and ion cyclotron frequency which is a natural resonance. LHDW is generally observed in transition layer regions and magnetic reconnection sites, where the gradient in density occurs. We are presenting electromagnetic kinetic model including gradients in density and magnetic field, finite parallel wavenumber and non-thermal particle distribution function or kappa velocity distribution function.  The effect of the aforementioned factors on the growth rate of LHDI in different plasma beta circumstances has been thoroughly investigated and will be discussed. Space observation of drift driven wave using MMS spacecraft will also be discussed.

How to cite: Arya, N. and Kakad, A.: Observational and Theoretical Study of Lower Hybrid Drift Waves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7061, https://doi.org/10.5194/egusphere-egu24-7061, 2024.

EGU24-7217 | Posters on site | ST1.4

Resonant Wave Excitations of Suprathermal Populations in the Solar Wind and Terrestrial Magnetosphere 

Shaaban Mohammed Shaaban Hamd, Rodrigo A. López, Marian Lazar, and Stefaan Poedts

It is believed that the suprathermal populations of electrons and protons in the solar wind and terrestrial magnetosphere (with energies exceeding those of the bulk population up to several keV) can offer key answers to many major problems, such as the origin of energetic solar particles from interplanetary shocks, particle acceleration by the energy dissipation of the small-scale wave fluctuations, but also a certain level of kinetic turbulence which can explain the non-equilibrium quasi-stable states of space plasmas. Due to their low density and relatively high energy, these populations are collisionless, which means that their dynamics is governed by wave-particle interactions, especially resonant Landau or cyclotron interactions. We present here a series of recent results that demonstrate that the suprathermal populations, whether in the form of a less-drifting halo or the field-aligned beams/strahls, are mainly responsible for the resonant excitation of kinetic wave instabilities. The in-situ observations confirm both the electromagnetic fluctuations triggered by temperature anisotropy and the predominantly electrostatic excitations induced for instance by electron beams.

How to cite: Hamd, S. M. S., López, R. A., Lazar, M., and Poedts, S.: Resonant Wave Excitations of Suprathermal Populations in the Solar Wind and Terrestrial Magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7217, https://doi.org/10.5194/egusphere-egu24-7217, 2024.

EGU24-7222 | ECS | Orals | ST1.4 | Highlight

Quantum Computing for Future Super Large-Scale Plasma Simulations: A Novel Approach for Simulating the Vlasov-Maxwell System 

Hayato Higuchi, Juan Pedersen, and Akimasa Yoshikawa

The space plasma environment, extending from the Sun to the Earth, includes regions of frozen conditions, zones of anomalous resistance caused by electromagnetic turbulence, interconnected regions characterized by weakly ionized gas systems in strong magnetic fields, coupled neutral-atmosphere chemical processes, and pure neutral-atmosphere collision systems. Owing to their complex interactions, an inclusive understanding and forecasting of the space environment remains an elusive goal, even with the advancements in high-performance instrumentation and in-situ observation of satellites. Therefore, it is imperative to develop space plasma simulations capable of providing comprehensive insights, ranging from local spatial domains to the global schematic.

Historically, the development of space plasma simulations has been constrained by computational time, memory capacity, and data storage limitations, resolving complex phenomena with restricted physics at local space scales.

Recently, as quantum computing hardware has advanced, quantum algorithms have proven to benefit exponential speedups. There has been a focus on the practical applications of quantum computing in finance, chemistry, fluids, and a variety of fields (e.g., Bouland et al.,[2020], Cao et al.,[2019], Egger et al.,[2020] and Budinski, [2022]). Then a quantum algorithm for the collisionless Boltzmann equation using the discrete velocity method was developed by (Todorova and Steijl, [2020]).

We have developed a quantum algorithm for the six-dimensional Boltzmann-Maxwell equations for collisionless plasmas with reference to (Higuchi, et al.,[2023]). We applied this methodology to propose a quantum approach that predicts kinetic and multiscale plasma dynamics.

In this presentation, we will introduce a quantum algorithm for performing super large- scale plasma simulations in a quantum computer and estimate the performance required by this task for future quantum error tolerant large-scale quantum computers. We will also discuss the prospects for applications that can be expected in our field, based on trends in the development of quantum computer hardware and software.

How to cite: Higuchi, H., Pedersen, J., and Yoshikawa, A.: Quantum Computing for Future Super Large-Scale Plasma Simulations: A Novel Approach for Simulating the Vlasov-Maxwell System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7222, https://doi.org/10.5194/egusphere-egu24-7222, 2024.

EGU24-8120 | Posters on site | ST1.4

Statistical mechanics of the electrons in the solar wind: stability and instability of whistler waves in the inner heliosphere 

Daniel Verscharen, Alfredo Micera, Maria Elena Innocenti, Jesse Coburn, Elisabetta Boella, Viviane Pierrard, Jingting Liu, Christopher J. Owen, Georgios Nicolaou, and Kristopher G. Klein

The electrons in the solar wind often exhibit non-equilibrium velocity distribution functions. Observed non-equilibrium electron features in the inner heliosphere include a field-aligned beam (called "strahl"), a suprathermal halo population, a sunward deficit in the distribution, and temperature anisotropy. These features are the result of a complex interplay between global expansion effects, collisions, and local interactions between the particles and the electromagnetic fields. Global effects create, for example, the strahl via the mirror force in the decreasing magnetic field and the sunward deficit via reflection effects in the interplanetary electrostatic potential. Local wave-particle interactions such as instabilities and wave damping change the shape of these signatures and thus the overall properties and moments of the electron distribution.

We discuss the formation of the relevant features in the electron distribution and analyse their impact on the linear stability of whistler waves in the inner heliosphere. We then present results from our numerical ALPS code that is capable of evaluating the linear stability of plasma with arbitrary background distributions. With results from our ALPS code, we show that the strahl-core-deficit configuration near the Sun drives oblique whistler waves unstable. However, it leads to enhanced damping of parallel whistler waves compared to a Maxwellian configuration. As the distribution evolves, the sunward deficit fills with electrons, at which point the plasma becomes unstable and drives parallel whistler waves. Our results highlight the need to treat electrons statistically as a globally inhomogeneous plasma component and to account for the detailed shape of their distribution in the evaluation of the plasma's linear stability.

How to cite: Verscharen, D., Micera, A., Innocenti, M. E., Coburn, J., Boella, E., Pierrard, V., Liu, J., Owen, C. J., Nicolaou, G., and Klein, K. G.: Statistical mechanics of the electrons in the solar wind: stability and instability of whistler waves in the inner heliosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8120, https://doi.org/10.5194/egusphere-egu24-8120, 2024.

EGU24-8372 | ECS | Posters on site | ST1.4

Understanding the effects of spacecraft trajectories through solar coronal mass ejection flux ropes using 3DCOREweb 

Hannah Theresa Rüdisser, Andreas J. Weiss, Christian Möstl, Ute V. Amerstorfer, Emma E. Davies, and Eva Weiler

A special observational signature in ICMEs that has puzzled researchers for a long time are so-called ”back regions” or ”magnetic-cloud-like (MCL)” parts of ICMEs which follow after the main flux rope rotation has passed the observer. These regions, occurring after the main flux rope rotation, display a peculiar behaviour where the magnetic field remains elevated with minimal rotation. Two proposed explanations involve magnetic reconnection during CME propagation or a purely geometric effect as the observer traverses the flux rope . 

We investigate in detail whether MCLs can be explained by an effect of the trajectory of an observer through a 3D expanding magnetic flux rope, without invoking magnetic reconnection as an explanation for those signatures. To this end, we employ the 3D coronal rope ejection (3DCORE) model, which has proven its ability to fit in situ magnetic fields of CME flux ropes. 

The model assumes an empirically motivated torus-like flux rope structure that expands self-similarly within the heliosphere, is influenced by a simplified interaction with the solar wind environment, and carries along an embedded analytical magnetic field. Developed for fitting, generating synthetic signatures, comparing models to observations, and analysing results, 3DCOREweb accelerates the determination of physical parameters, fostering research on the global magnetic structure of CMEs. Additionally, the interface aids in advancing our understanding of magnetic flux rope signatures arising from diverse 3D trajectories through CMEs.

How to cite: Rüdisser, H. T., Weiss, A. J., Möstl, C., Amerstorfer, U. V., Davies, E. E., and Weiler, E.: Understanding the effects of spacecraft trajectories through solar coronal mass ejection flux ropes using 3DCOREweb, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8372, https://doi.org/10.5194/egusphere-egu24-8372, 2024.

EGU24-8536 | ECS | Posters on site | ST1.4

The effect of the thermal properties of electrons on the dispersion of kinetic Alfvén waves 

Nicolás Francisco Sepúlveda, Pablo S. Moya, Rodrigo A. López, and Daniel Verscharen

The kinetic Alfvén wave (KAW) is an extension of the Alfvén mode to the kinetic scales that propagates at quasi-perpendicular angles with respect to the background magnetic field in a magnetized plasma. The KAW is characterized by a right-handed polarization in the plane orthogonal to the background magnetic field. This allows the KAW to resonate with electrons, as contrary to the electromagnetic ion-cyclotron (EMIC) wave, which resonates with positive ions due to it’s its left-handed polarization. The EMIC mode is also a kinetic extension of the classical Alfvén wave, and propagates at quasi-parallel wavenormal angles. Due to the relevance and overall presence of both of these modes in space plasmas, understanding the nature of the transition from the EMIC mode to the KAW is a matter of great interest for the study of the micro-scale physics of these systems.

The transition from left-hand to right-hand polarized Alfvén waves depends on the wavenumber, plasma beta, temperature anisotropy, and ion composition of the plasma. Along with the temperature anisotropy, the electron-to-proton temperature ratio Te/Tp is of great relevance for the characterization of the thermal properties of a plasma. This ratio varies significantly between different space plasma environments. Thus, studying how variations on this ratio affect the polarization properties of electromagnetic waves becomes of high relevance highly relevant
for our understanding of the dynamics of space plasmas.

In this work, we present an extensive study on the effect of the thermal properties of electrons on the behaviour and characteristics of Alfvénic waves in fully kinetic linear theory, as well as on the transition from EMIC to KAW. We show that the temperature ratio Te/Tp has strong and non-trivial effects on the polarization of the Alfvénic modes, especially at kinetic scales (kρL>1, where k=k sinθ and ρL= cs/Ωp, with cs the plasma sound speed and Ωp the proton’s gyrofrequency) and βep>0.5, where βs=8πnkTs/B2 is the ratio between thermal and magnetic pressure. We conclude that electron inertia plays an important role in the kinetic scale physics of the KAW in the warm plasma regime, and thus cannot be excluded in hybrid models for computer simulations.

How to cite: Sepúlveda, N. F., Moya, P. S., López, R. A., and Verscharen, D.: The effect of the thermal properties of electrons on the dispersion of kinetic Alfvén waves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8536, https://doi.org/10.5194/egusphere-egu24-8536, 2024.

EGU24-11114 | ECS | Posters on site | ST1.4

How will interplanetary magnetic field topology modify solar wind kinetics? 

Rong Lin, Giovanni Lapenta, and Jiansen He

Recent observations of the interplanetary magnetic field have enlarged the magnetic field topology family in the inner heliosphere, and raises interest in the relationship between those topologies and the evolution of solar wind. For example, switchbacks that are kinks of magnetic field lines accompanied by velocity spikes and enhancement of the proton parallel temperature, have free energy both of the field and of the particles, and thus have potential for a series of plasma instabilities. It is favorable to extract elementary topologies from complicated structures like switchbacks before we look further in. Based on Particle-in-Cell simulations, we discuss from elementary topologies on the effect they have on kinetic processes of the solar wind plasma.

How to cite: Lin, R., Lapenta, G., and He, J.: How will interplanetary magnetic field topology modify solar wind kinetics?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11114, https://doi.org/10.5194/egusphere-egu24-11114, 2024.

EGU24-11324 | Orals | ST1.4

AWSoM solar wind model with charge states and ion temperatures 

Bart van der Holst, Enrico Landi, and Tamas Gombosi

We present a multi-ion generalization of the AWSoM model, a 3D global magnetohydrodynamic (MHD) solar corona and inner heliosphere model with incompressible turbulence. The AWSoM model with charge states is further extended to include temperatures for the various heavy ion species. The coronal heating is addressed via outward propagating low-frequency Alfven waves that are partially reflected by Alfven speed gradients. The nonlinear interaction of these counter-propagating waves results in turbulent energy cascade. To apportion the cascaded turbulent energies to the electron and ion temperatures, we employ the results of the theories of linear wave damping and nonlinear stochastic heating. This heat partitioning results in a mass proportional heating among ions.

How to cite: van der Holst, B., Landi, E., and Gombosi, T.: AWSoM solar wind model with charge states and ion temperatures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11324, https://doi.org/10.5194/egusphere-egu24-11324, 2024.

EGU24-13542 | ECS | Posters on site | ST1.4

 Change Ratios of Magnetic Helicity and Magnetic Free Energy During MajorSolar Flares  

Quan Wang, Shangbin Yang, Mei Zhang, Xiao Yang, and Xiaoshuai Zhu

Magnetic helicity is an important concept in solar physics, with a number of theoretical statements pointing out the important role of magnetic helicity in solar flares and coronal mass ejections (CMEs). Here we construct a sample of 47 solar flares, which contains 18 no-CME-associated confined flares and 29 CME-associated eruptive flares. We calculate the change ratios of magnetic helicity and magnetic free energy before and after these 47 flares. Our calculations show that the change ratios of magnetic helicity and magnetic free energy show distinct different distributions in confined flares and eruptive flares. The median value of the change ratios of magnetic helicity in confined flares is −0.8%, while this number is −14.5% for eruptive flares. For the magnetic free energy, the median value of the change ratios is −4.3% for confined flares, whereas this number is −14.6% for eruptive flares. This statistical result, using observational data, is well consistent with the theoretical understandings that magnetic helicity is approximately conserved in the magnetic reconnection, as shown by confined flares, and the CMEs take away magnetic helicity from the corona, as shown by eruptive flares.

How to cite: Wang, Q., Yang, S., Zhang, M., Yang, X., and Zhu, X.:  Change Ratios of Magnetic Helicity and Magnetic Free Energy During MajorSolar Flares , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13542, https://doi.org/10.5194/egusphere-egu24-13542, 2024.

EGU24-15727 | ECS | Posters on site | ST1.4

Coronal Bright Points observed in the corona and photosphere with SDO and Hinode 

Isabella Kraus and Philippe Bourdin

The exact coronal heating mechanism remains a riddle, but magnetically active regions are known to host coronal loops with extreme-UV emission. But also at much smaller sizes, up to 10 Mm, there are bipolar regions that can be associated with UV emission in coronal bright points (CBPs). We study the statistical properties of CBPs with continuous data from the SDO spacecraft to track the lifetime of CBPs. We use their tracking data to verify that the lower corona co-rotates with the photosphere. In a next step, we aim to reproduce an isolated CBP in a 3D magneto-hydrodynamic (MHD) simulation. To this end, we need observational data to drive the simulation from both, SDO/HMI and Hinode/NFI. As these instruments feature different resolutions and field-of-views, they also detect different levels of small-scale and large-scale magnetic structures in the photosphere. As we know, these magnetic patches are advected from photospheric horizontal motions and create the necessary Poynting flux at the base of the corona. Combining these data from two very different instruments is a task that needs careful overlaying, so that not artificial effects would appear in the MHD simulation. We use a multi-scale overlaying method to enlarge the field-of-view of Hinode with SDO data, to drive the simulation with consistent photospheric magnetic fields. The bottom and top boundaries are fully closed for any mass and heat flows. The output of the simulation will allow us to compute synthetic UV emission maps that we may compare directly to SDO and Hinode observations. With our model we test if the field-line braiding mechanism is sufficient to heat a CPB to the required temperature. We find that loop-like CBPs usually originate from bipolar regions. Weaker magnetic polarities produce fainter and hence cooler CBPs. And the same time, we find that lifetimes of typical CPBs are easily more than 6 hours. This supports the theory that the heating of CBP is mainly based on magnetic energy dissipation through a relatively steady and slow magnetic reconnection process.

How to cite: Kraus, I. and Bourdin, P.: Coronal Bright Points observed in the corona and photosphere with SDO and Hinode, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15727, https://doi.org/10.5194/egusphere-egu24-15727, 2024.

EGU24-16790 | ECS | Posters virtual | ST1.4

Understanding the Thermal Properties of Fast CMEs by Integrating White-light Observations and Analytical Modeling 

Soumyaranjan Khuntia and Wageesh Mishra

Coronal Mass Ejections (CMEs), huge magnetized plasma erupting from the Sun, pose potential risks to space weather and space-based infrastructure. While extensive research has focused on examining the kinematics of CMEs, there has been limited study of their thermodynamic evolution, particularly at specific heliocentric distances closer to the Sun. Acknowledging that variations in internal plasma properties can impact the overall evolution of CMEs and vice versa is crucial. This study investigates diverse kinematic profiles and associated thermodynamic changes in nine fast CMEs at coronal heights where measuring thermodynamics is challenging. We estimated the distance-dependent evolution of various internal parameters, including polytropic index, temperature, heating rate, pressure, and internal forces driving CME expansion by leveraging the improved Flux Rope Internal State (FRIS) model. The FRIS model utilizes the 3D kinematics derived from the Graduated Cylindrical Shell (GCS) model as input. Our findings reveal that CMEs can maintain their temperature above the adiabatic cooling threshold despite expansion, progressing towards an isothermal state during later propagation phases. The fast CMEs maintaining higher expansion speeds exhibit less pronounced temperature decreases. We found that CME's expansion speed and acceleration correlate well with its maximum temperature drop to reach the isothermal state. Multi-wavelength observations of flux ropes at the source region support the FRIS model-derived results at lower coronal heights. Our analysis elucidates that the primary forces influencing CME radial expansion are the centrifugal and thermal pressure forces, while the Lorentz force acts as a constraining factor. Notably, the thermal pressure force governs expansion at higher heights and is solely responsible for radial expansion. This study enhances our comprehension of the thermodynamic properties of fast CMEs, offering valuable insights for refining assumptions of the polytropic index value in different magnetohydrodynamics (MHD) models to improve the prediction of CME properties at 1 AU.

How to cite: Khuntia, S. and Mishra, W.: Understanding the Thermal Properties of Fast CMEs by Integrating White-light Observations and Analytical Modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16790, https://doi.org/10.5194/egusphere-egu24-16790, 2024.

EGU24-17085 | ECS | Posters on site | ST1.4

Exploring Solar Energetic Particles Transport in the Inner Heliosphere 

Ahmed Houeibib, Filippo Pantellini, and Léa Griton

We simulate the propagation of relativistic test particles within the field of a 3D MHD simulation of the solar wind. The adiabatic ideal MHD equations are integrated numerically using the MPI-AMRVAC code. Test particles are initialized within the MHD simulation grid and advanced in time according to the guiding center equations, we employ a third-order accurate time prediction-correction method from Mignone et al. 2023 for integration. We also include possibility of diffusion in velocity space based on a particle-turbulence mean free path λ∥ along the magnetic field line. One of the first results where we consider 81 keV electrons injected at 0.139 AU heliocentric distance and mean free path λ∥ = 0.5 AU is in good qualitative agreement with measurements at 1 AU.

How to cite: Houeibib, A., Pantellini, F., and Griton, L.: Exploring Solar Energetic Particles Transport in the Inner Heliosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17085, https://doi.org/10.5194/egusphere-egu24-17085, 2024.

How the solar wind heat flux is constrained and how strahl electrons are scattered are two fundamental problems in the study of the electron dynamics in the solar wind. Recently, much attention has been paid to the role of the electron heat flux instability on these two problems. We have performed the instability analyses for the electron heat flux instability in the near-Sun solar wind where the plasma beta is much lower than one. We found that lower-hybrid waves and oblique Alfvén waves can be primarily triggered by the electron heat flux in the low-beta plasma environment, and we also explored the wave-particle interactions in each type instability through the energy transfer rate method. Moreover, using PSP observations, we will show the possible observation signature for the lower-hybrid waves in the near-Sun solar wind.

How to cite: Zhao, J.: Electron heat flux instability in the near-Sun solar wind, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17196, https://doi.org/10.5194/egusphere-egu24-17196, 2024.

EGU24-18011 | ECS | Posters on site | ST1.4

Simulations of Langmuir-wave emission by magnetic holes in the solar wind 

Jingting Liu, Daniel Verscharen, Jesse Coburn, Jeffersson Agudelo, Kai Germaschewski, Hamish Reid, Georgios Nicolaou, and Christopher Owen

Langmuir waves are frequently detected in the solar wind and affect the energetics of the plasma electrons. Previous observational studies have found Langmuir waves associated with magnetic holes in the solar wind. In our work, we aim to understand the connection between magnetic holes and these waves.

The Langmuir instability is a well-known consequence of electron beams in plasmas. We use particle-in-cell (PIC) simulations of a collisionless electron-ion plasma in a magnetic hole structure. We study the triggering of Langmuir waves by inhomogeneous beam instabilities in this configuration.

Our simulations reveal patterns that suggest that injecting a beam into the magnetic hole has the potential to create spatially inhomogeneous Langmuir wave packets by instability. We support our PIC simulations with linear stability calculations and discuss the conditions required for magnetic holes to emit Langmuir waves through our proposed mechanism. Our simulation results will be used in comparative studies with observational data of Langmuir-wave emitting magnetic holes.

 

 

How to cite: Liu, J., Verscharen, D., Coburn, J., Agudelo, J., Germaschewski, K., Reid, H., Nicolaou, G., and Owen, C.: Simulations of Langmuir-wave emission by magnetic holes in the solar wind, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18011, https://doi.org/10.5194/egusphere-egu24-18011, 2024.

EGU24-18200 | ECS | Posters on site | ST1.4

Modelling the formation and  evolution of solar wind microstreams:from coronal plumes to propagating Alfvénic velocity spikes. 

Bahaeddine Gannouni, Victor Réville, and Alexis Rouillard

Our research delves into solar wind's mesoscale features known as microstreams—periods of heightened speed and temperature lasting hours. Initially observed in Helios and Ulysses data, they're now prevalent in the 'young' solar wind by Parker Solar Probe and Solar Orbiter. Recent findings unveil microstreams' carriage of abundant Alfvénic perturbations—velocity spikes and magnetic switchbacks.

Employing a high-resolution 2.5 MHD model, we scrutinize the genesis of microstreams from emerging bipoles interacting with the ambient corona. Our simulations reveal the tearing-mode instability, forming plasmoids released into the solar wind. Our domain spans the lower corona to 20 Rs, enabling observation of plasmoid formation and their evolution into Alfvénic spikes (Gannouni et al. 2023). The magnetic emergence rate modulates microstream characteristics.

Additionally, 3D MHD simulations explore intermittent interchange reconnection in a 24x24x30Mm domain with a flux emergence rate of 1.38G/s. Reconnection spawns plasma jets and twisted magnetic field bundles, releasing hot plasma into the solar wind, inducing propagating waves and twists along magnetic field lines.

How to cite: Gannouni, B., Réville, V., and Rouillard, A.: Modelling the formation and  evolution of solar wind microstreams:from coronal plumes to propagating Alfvénic velocity spikes., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18200, https://doi.org/10.5194/egusphere-egu24-18200, 2024.

    Solar and interplanetary radio bursts are important phenomena to reflect the electron acceleration and kinetic process in the corona and space plasmas. The near-Sun radio observation by Parker Solar Probe (PSP) provides an good chance to make the approach and in situ measurements for the emission source of radio bursts. According to the radio dynamic spectrum, we found that a large number of weak radio bursts with higher cutoff frequency flo can only be detected by PSP. These bursts have several obvious characteristics: (1) short duration (1-5 min); (2) narrow frequency band (0.5-15 MHz); (3) weak peak intensity (~ 10-15 V2/Hz). Their relative frequency drift rate decreases from > 0.01 s-1 to < 0.01 s-1 implies that they are not the typical type III and II radio bursts. Based on the plasma empirical models and the data from in situ detection by PSP, the fitted models indicate that the radiation of these bursts might be generated by the electron cyclotron maser emission in the acceleration region of solar wind (1.1-10 RS). The spectral characteristics of these bursts manifest that these bursts come from small-scale emission source, which have experienced strong kinetic evolution. We propose that these weak bursts are possibly the solitary wave radiation (SWR) generated from electron cyclotron maser instability with the energetic electrons trapped and accelerated by solitary kinetic Alfvén wave (SKAW) in the close magnetic structure. The decay of SKAW can well explain the deceleration of the emitting sources and the short duration.

How to cite: Ma, B., Chen, L., and Wu, D.-J.: Emission Mechanism of radio bursts from the Solar Wind Acceleration Region observed by Parker Solar Probe in near-Sun plasmas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18356, https://doi.org/10.5194/egusphere-egu24-18356, 2024.

EGU24-18387 | ECS | Posters on site | ST1.4

Implementation of Boundary Conditions for Nonlinear Force-Free Field Computations Using Vector Potentials 

Minseon Lee, Gwangson Choe, and Sibaek Yi

A nonlinear force-free field is solely determined by the normal components of magnetic field and current density on the entire boundary of the domain. Methods using three components of magnetic field suffer from either overspecification of boundary conditions and/or a nonzero divergence B problem. A vector potential formulation eliminates the latter issue, yet poses difficulties in imposing normal components of both magnetic field and current density on the boundary. This challenge arises due to the inability to fix all three components of the vector potential at the boundary while the vector potential within the interior domain undergoes iterative changes.

This paper explores four distinct boundary treatment approaches within the vector potential formulation. In two methods, the normal component of the vector potential is adjusted to satisfy the prescribed boundary-normal component of current density at each iteration, while the tangential components remain fixed throughout. In the other two methods, the tangential components of the vector potential are modified at each iteration, while the normal component remains fixed. Each group comprises both first-order and second-order boundary treatments. We conduct a comparative analysis of these methods against our established poloidal-toroidal formulation code and the optimization code in Solar Software.

While none of the four methods outperform our poloidal-toroidal formulation code, they demonstrate comparable or superior performance compared to the latter. This research is regarded to provide insights into optimizing boundary conditions for data-driven simulations using vector potentials. 

How to cite: Lee, M., Choe, G., and Yi, S.: Implementation of Boundary Conditions for Nonlinear Force-Free Field Computations Using Vector Potentials, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18387, https://doi.org/10.5194/egusphere-egu24-18387, 2024.

EGU24-20270 | ECS | Posters on site | ST1.4

Temperature inversion in a gravitationally bound plasma: Case of the solar corona 

Luca Barbieri, Lapo Casetti, Andrea Verdini, Simone Landi, Emanuele Papini, and Pierfrancesco Di Cintio

The temperature of the solar atmosphere increases from thousands to millions of degrees moving from the lower layer (chromosphere) to the outermost one (corona), while the density drops accordingly. The mechanism behind this phenomenon, known as a temperature inversion, is still unknown. In this work, we model a coronal loop as a collisionless plasma confined in a semicircular tube that is subject to the Sun's gravity and in thermal contact with a fully collisional chromosphere behaving as a thermostat at the loop's feet. By using kinetic N-particle simulations and analytical calculations, we show that rapid, intermittent, and short-lived heating events in the chromosphere drive the coronal plasma towards a non-equilibrium stationary state. The latter is characterized by suprathermal tails in the particles velocity distribution functions, exhibiting temperature and density profiles strikingly similar to those observed in the atmosphere of the Sun. These results suggest that a million-Kelvin solar corona can be produced without the local deposition of heat in the upper layer of the atmosphere that is typically assumed by standard approaches. We find that suprathermal distribution functions in the corona are self-consistently produced instead of postulated a priori, in contrast to classical kinetic models based on a velocity filtration mechanism.

How to cite: Barbieri, L., Casetti, L., Verdini, A., Landi, S., Papini, E., and Di Cintio, P.: Temperature inversion in a gravitationally bound plasma: Case of the solar corona, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20270, https://doi.org/10.5194/egusphere-egu24-20270, 2024.

EGU24-417 | ECS | Orals | ST1.5

Connecting the early temporal evolution of solar energetic particles to the properties of coronal shock waves 

Manon Jarry, Nina Dresing, Rami Vainio, Alexis Rouillard, Illya Plotnikov, and Athanasios Kouloumvakos

Solar energetic particle (SEP) events, particularly those of significant magnitude, are commonly associated with fast and wide coronal mass ejections (CMEs). These CMEs generate and drive shock waves in the solar corona, proving to be highly efficient in particle acceleration to high energies. Understanding the intricate connections between shock wave properties and SEP characteristics is crucial for advancing Space Weather forecasting.
To achieve this objective, we employ a methodology to analyze a SEP event involving a coronal shock wave, observed by several spacecraft well distributed around the Sun. Initially, we reconstruct the 3D ellipsoidal shape of the expanding shock, enabling the extraction of its geometry and kinematic properties. Using magneto-hydrodynamics (MHD) cubes, we then reconstruct the magnetic connectivity of spacecrafts and retrieve the MHD properties of the shock wave at the intersections with these magnetic field lines. The temporal correlations between the shock properties and the SEPs recorded by individual spacecraft can finally be compared.
Through the application of this methodology, we identify enhanced correlation coefficients between SEPs and shock parameters, such as speed, Alfvénic Mach Number, and theta_BN (the angle between the shock's normal and the magnetic field line). 
This work is funded by the H2020 SERPENTINE project.

How to cite: Jarry, M., Dresing, N., Vainio, R., Rouillard, A., Plotnikov, I., and Kouloumvakos, A.: Connecting the early temporal evolution of solar energetic particles to the properties of coronal shock waves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-417, https://doi.org/10.5194/egusphere-egu24-417, 2024.

EGU24-1309 | Orals | ST1.5 | Highlight

Study of major historical GLEs on the basis of historical records  

Alexander Mishev, Hisashi Hayakawa, Sergey Koldobskiy, Stepan Poluianov, and Ilya Usoskin

A methodological study of relativistic solar energetic particles provides the necessary basis to reveal the nature of various processes, such as the production and acceleration of energetic particles at the Sun, their transport in the interplanetary medium, interactions of energetic particles with magnetic fields in the heliosphere, the induced corresponding terrestrial and space weather effects. Following solar eruptive processes, such as solar flares and/or coronal mass ejections solar ions are accelerated to a high-energy range. When the energy of the accelerated solar proton reaches the GeV/n range, it is enough high, so that solar ions generate an atmospheric cascade in the Earth’s atmosphere, whose secondary particles reach the ground, eventually registered by ground-based detectors, such as neutron monitors (NMs). This particular class of events is known as ground-level enhancements (GLEs).

 

Over several decades, NMs provided the main records allowing analysis of GLEs, namely their spectral and anisotropy characteristics, a procedure requiring complicated modeling and several NM stations (records starting from GLE #5, 23-Feb-1956). However, the first four GLEs were recorded mostly by ionization chambers (ICs), devices with a weaker responses and greater energy threshold compared to NMs. Here, we analyzed several GLEs on the basis of historical records, where data of NMs and IC are both available. As a first step, we derived the GLE protons spectra employing a method verified by space-borne measurements. Secondly, employing a forward modeling, we rescaled the response of the available ICs, that is, we assessed the response function of selected ICs. Finally, employing a procedure similar to GLE analysis using NMs, but here using ICs records, we derived for the first time the spectra of e.g. GLE # 4. We compared the derived spectra with GLE #5 and discussed the obtained results.

How to cite: Mishev, A., Hayakawa, H., Koldobskiy, S., Poluianov, S., and Usoskin, I.: Study of major historical GLEs on the basis of historical records , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1309, https://doi.org/10.5194/egusphere-egu24-1309, 2024.

EGU24-2823 | Posters on site | ST1.5

Unusually long path length for a nearly scatter-free solar particle event observed by Solar Orbiter at 0.43 au 

Robert F. Wimmer-Schweingruber, Liu Yang, Alexander Kollhoff, Raúl Gomez-Herrero, Javier Rodriguez-Pacheco, Francisco Espinosa, Ignacio Cernuda, George C. Ho, Glenn M. Mason, Alexander Warmuth, Christopher J, Owen, Luciano Rodriguez, Daria Shukhobodskaia, Lars Berger, Patrick Kühl, Bernd Heber, Linghua Wang, Radoslav Bucik, and Olga Malandraki

Solar energetic particles (SEPs) are bound to the interplanetary magnetic field (IMF) by the Lorentz force. The expansion of the IMF close to the Sun focuses the particle pitch-angle distribution, and scattering counteracts this focusing. Solar Orbiter observed an unusual solar particle event on 9 April 2022 when it was at 0.43 astronomical units (au) from the Sun. The inferred IMF along which the SEPs traveled was about three times longer than the nominal length of the Parker spiral.

Nevertheless, the pitch-angle distribution of the particles of this event is highly anisotropic, and the electrons and ions appear to be streaming along the same IMF structures. The angular width of the streaming population is estimated to be approximately 30 degrees. The highly anisotropic ion beam was observed for more than 12 h. This may be due to the low level of fluctuations in the IMF, which in turn is very probably due to this event being inside an interplanetary coronal mass ejection. The slow and small rotation in the IMF suggests a flux-rope structure. Small flux dropouts are associated with very small changes in pitch angle, which may be explained by different flux tubes connecting to different locations in the flare region. The unusually long path length along which the electrons and ions have propagated virtually scatter-free together with the short-term flux dropouts offer excellent opportunities to study the transport of SEPs within interplanetary structures. The 9 April 2022 solar particle event offers an especially rich number of unique observations that can be used to limit SEP transport models.

How to cite: Wimmer-Schweingruber, R. F., Yang, L., Kollhoff, A., Gomez-Herrero, R., Rodriguez-Pacheco, J., Espinosa, F., Cernuda, I., Ho, G. C., Mason, G. M., Warmuth, A., Owen, C. J., Rodriguez, L., Shukhobodskaia, D., Berger, L., Kühl, P., Heber, B., Wang, L., Bucik, R., and Malandraki, O.: Unusually long path length for a nearly scatter-free solar particle event observed by Solar Orbiter at 0.43 au, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2823, https://doi.org/10.5194/egusphere-egu24-2823, 2024.

EGU24-2836 | Posters on site | ST1.5

The alignment of  STEREO-A and Earth: A unique opportunity to investigate Solar Energetic Particle events. 

Bernd Heber, Daniela Banys, Jens Berdermann, Henrik Dröge, Malte Hörlöck, Alexander Kollhoff, Patrick Kühl, Olga Malandraki, Janna Martens, Arik Posner, and Holger Sierks

A major impact on human and robotic space exploration activities is the sudden and prompt occurrence of solar energetic ion events. In 2023 and 2024,  {STEREO} is approaching the Earth from a behind position, soon passing Earth inside its orbit and thereafter moving ahead of Earth.  {STEREO} thus offers several unique opportunities during this passage. In the period from June 1 to November 1, 2023, 5 {SEP} events have been measured that cause proton fluxes of above 25~MeV to rise above 0.1 /(cm$^2$\; s\; sr\; MeV). Taking into account systematic and statistical uncertainties of the particle measurements we find a good agreement between both spacecraft.

The SOHO/EPHIN and STEREO/SEPTproject is supported under Grant 50~OC~2102 by the German Bundesministerium für Wirtschaft through the Deutsches Zentrum für Luft- und Raumfahrt (DLR). This study has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 101004159 (SERPENTINE).

How to cite: Heber, B., Banys, D., Berdermann, J., Dröge, H., Hörlöck, M., Kollhoff, A., Kühl, P., Malandraki, O., Martens, J., Posner, A., and Sierks, H.: The alignment of  STEREO-A and Earth: A unique opportunity to investigate Solar Energetic Particle events., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2836, https://doi.org/10.5194/egusphere-egu24-2836, 2024.

Solar eruptions can accelerate solar energetic particles (SEPs) to high energies which can, if they have sufficient energy, penetrate the Earth’s magnetic environment leading to numerous space weather hazards that can affect infrastructure and human health. Strong SEP events can be detected by ground-based neutron monitors (NMs) and registered at the Earth’s surface as ground-level enhancements (GLEs) if several NMs detect a significant increase in cosmic-ray count rates caused by arriving SEPs. The increase in the flux of high-energy particles entering the atmosphere during GLEs enhances the complex radiation environment at high altitudes which can pose a serious risk to airplane crew and passengers. As such there is a strong desire to develop nowcasting models that can quickly estimate the impact of GLEs on human health to help mitigate the threat GLEs pose. One avenue of approaching this issue is the development and application of proxies that allow for quick conservative estimates of the hazards. In this work, 21 of the 73 currently recorded GLEs have been analysed using the same verified method revealing the SEP characteristics during the events. These characteristics are used as inputs into a newly developed CRAC:DOMO radiation model to compute the radiation dose experienced at aviation altitudes. A comparison was then done with the real-time NM data during the GLE events to establish a relationship between the modelled dose and empirical NM data through a large statistical analysis. This was successful, with a very strong relationship being shown between the two variables. This result provides scientific support for using real-time NM data as a potential proxy in future nowcasting models aimed at estimating and mitigating the impacts of GLEs on humans and the aviation industry.

How to cite: Larsen, N. and Mishev, A.: Investigating the Potential for Using Real-Time Neutron Monitor Data as a Proxy for Estimating the Impact of Ground-Level Enhancements on Radiation Doses at Aviation Altitudes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3470, https://doi.org/10.5194/egusphere-egu24-3470, 2024.

EGU24-3846 | Orals | ST1.5 | Highlight

Downstream jets at interplanetary shocks: first observations and comparison with the magnetosheath 

Heli Hietala, Domenico Trotta, Annamaria Fedeli, Lynn B. Wilson III, Laura Vuorinen, Adrian T. LaMoury, and Jesse T. Coburn

Localised dynamic pressure enhancements—jets—are regularly observed downstream of the Earth’s bow shock. They drive enhanced particle acceleration, larger amplitude magnetic field variations and reconnecting current sheets. Various shock simulations have also exhibited jets, suggesting that they are not unique to the bow shock.

Here, we report the first observations of jet-like structures downstream of interplanetary shocks. We introduce an analysis approach suitable for such conditions and apply it to Wind spacecraft data using tools developed in the EU-project SERPENTINE. We first demonstrate the methods on a particularly high Mach number interplanetary shock that has properties comparable to the Earth’s bow shock. To further our understanding, we also investigate two low beta, low Mach number interplanetary shocks, i.e., conditions that are rare for the bow shock.

The jet-like structures we find are tens of ion inertial lengths in size, and some are observed further away from the shock than in a limited magnetosheath. We find that their properties are similar to those of magnetosheath jets: in the frame of the shock these structures are fast, cold, and most have no strong magnetic field variations. All three interplanetary shocks feature foreshock activity, but no strongly compressive waves. We discuss the implications these findings have for the proposed jet formation mechanisms. The prospects of observing downstream jets in further detail with future missions look promising.

How to cite: Hietala, H., Trotta, D., Fedeli, A., Wilson III, L. B., Vuorinen, L., LaMoury, A. T., and Coburn, J. T.: Downstream jets at interplanetary shocks: first observations and comparison with the magnetosheath, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3846, https://doi.org/10.5194/egusphere-egu24-3846, 2024.

It is shown that the first order Fermi acceleration of cosmic rays, based on a concept of ions reflected by shocks, is equivalent to the ballistic surfing acceleration (BSA) by the convection electric field. Despite big differences in the physics of the processes involved, both models lead to the same expression for the energy gain of a particle after one encounter with the shock, and consequently to the same power-law distribution of the cosmic ray energy spectrum after many encounters. BSA accelerates ions continuously from superthermal energies of 100eV up to very high energies observed in the cosmic ray spectrum. It is shown that the ‘knee’ observed in the spectrum at energy of 5×1015 eV could correspond to ions with gyroradius comparable to the size of shocks in supernova remnants.
It has been established that thermalization, heating, and energization of ions and electrons in collisionless shocks are related to the following plasma processes:

BSA – ballistic surfing acceleration
SWE –  stochastic wave energization
TTT – transit time thermalization
QAH – quasi adiabatic heating

References:
[1] K. Stasiewicz, MNRAS. 527, L71 (2023), Origin of flat-top electron distributions at the Earth’s bow shock, https://doi.org/10.1093/mnrasl/slad146
[2] K. Stasiewicz, MNRAS. 524, L50 (2023), Transit time  thermalization  and the stochastic wave energization of ions  in quasi-perpendicular shocks,  https://doi.org/10.1093/mnrasl/slad071
[3] K. Stasiewicz, B. Eliasson, MNRAS 520, 3238 (2023), Electron heating mechanisms at the bow shock - revisited with Magnetospheric Multiscale measurements, https://doi.org/10.1093/mnras/stad361

How to cite: Stasiewicz, K.: Reinterpretation of the Fermi acceleration of cosmic rays in terms of the ballistic surfing acceleration in shocks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4672, https://doi.org/10.5194/egusphere-egu24-4672, 2024.

EGU24-4847 | Orals | ST1.5 | Highlight

A comparison study of the impact of large Solar Energetic Particle events on the Moon and Mars  

Jingnan Guo, Jian Zhang, Bailiang Liu, and Mikhail Dobynde

Human beings are considering going back to the Moon and eventually to Mars within the next decades. However, we are still facing one major hurdle ``space radiation'' which is a significant and unavoidable risk for crews' health, especially for long-term stays at future lunar or martian stations. In particular, sporadic solar energetic particles (SEPs) generated via extreme solar eruptions may enhance the lunar or martian surface radiation levels to potentially hazardous values. Recent lunar and martian surface and orbital radiation detectors have advanced our understanding of the radiation environment of both planetary bodies. We have used the state-of-the-art modeling appoaches to study the radiation environment of the Moon and Mars. In particular, we study and compare the potential radiation effects of historically large SEP events on the surface and subsurface of the Moon and Mars.

How to cite: Guo, J., Zhang, J., Liu, B., and Dobynde, M.: A comparison study of the impact of large Solar Energetic Particle events on the Moon and Mars , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4847, https://doi.org/10.5194/egusphere-egu24-4847, 2024.

EGU24-5389 | Orals | ST1.5

Quantifying the uncertainty associated with solar energetic particle transport models 

Du Toit Strauss, Jaclyn Lang, Eugene Engelbrecht, and Jabus van den Berg

Using magnetically well-connected solar energetic particle (SEP) observations, we derive the electron and proton parallel mean-free-paths (MFPs) by comparing in-situ observations to one-dimensional simulation results. These inferred MFPs are compared to theoretical estimates which have been constrained by solar wind turbulence observations. We show that these derived and theoretical values are mostly consistent for both protons and electrons, but do show significant inter-event variations which can be explained by changing solar wind turbulence conditions. To illustrate the influence of these changing scattering conditions on particle transport, we simulate SEP time profiles for magnetically connected and unconnected observers for different transport and/or acceleration parameters. We show that this can explain the observer inter-event variations observed for SEP events. Additionally, we show that such an ensemble modeling approach can be used to quantify the uncertainty in the underlying model assumptions and can, in principle, be used in physics-based SEP predictive models to produce SEP predictions that include an uncertainty band.

How to cite: Strauss, D. T., Lang, J., Engelbrecht, E., and van den Berg, J.: Quantifying the uncertainty associated with solar energetic particle transport models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5389, https://doi.org/10.5194/egusphere-egu24-5389, 2024.

EGU24-5558 | Orals | ST1.5

Connecting remote and in situ observations of shock-accelerated electrons associated with a coronal mass ejection 

Diana Morosan, Jens Pomoell, Christian Palmroos, Nina Dresing, Eleanna Asvestari, Jan Gieseler, Anshu Kumari, and Immanuel Jebaraj

Energetic particle populations are ubiquitous throughout the Universe and often found to be accelerated by astrophysical shocks. One of the most prominent sources for energetic particles in our solar system are huge eruptions of magnetized plasma from the Sun called coronal mass ejections (CMEs), which usually drive shocks that accelerate charged particles up to relativistic energies. Accelerated electrons can be observed remotely as low-frequency radio bursts or in situ at spacecraft. However, it is currently unknown where electrons accelerated in the early phases of such eruptions propagate and when they escape the solar atmosphere to eventually reach spacecraft. Here, we present a new study that uses a three-dimensional representation of radio emission locations in relation to the overlying coronal magnetic field, shock wave propagation, magneto-hydrodynamic (MHD) models of the solar corona, and radio imaging observations from ground-based observatories. These solar observations are also combined with in situ electron data at spacecraft.  Our results indicate that if the in situ electrons are shock-accelerated, their most likely origin is at or near the acceleration site of electrons beams producing herringbone radio bursts. This is the only region during the early evolution of the CME where there is clear evidence of electron shock acceleration and intersection of the CME shock with open field lines that can connect to the observing spacecraft.

How to cite: Morosan, D., Pomoell, J., Palmroos, C., Dresing, N., Asvestari, E., Gieseler, J., Kumari, A., and Jebaraj, I.: Connecting remote and in situ observations of shock-accelerated electrons associated with a coronal mass ejection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5558, https://doi.org/10.5194/egusphere-egu24-5558, 2024.

EGU24-5753 | ECS | Posters on site | ST1.5

Daily heliospheric modulation potential (V23) and modelled GCR dataset compared to space measurements of the GCR energy spectrum. 

Pauli Väisänen, Bruna Bertucci, Nicola Tomassetti, Miguel Orcinha, Matteo Duranti, and Ilya Usoskin

The activity of the Sun modulates the fluxes of galactic cosmic rays arriving at Earth. This heliospheric modulation of cosmic rays is often quantified by the modulation potential, which describes the average energy loss of particles during their transport in the heliosphere. The modulation potential is a useful parameter not only for understanding the behaviour of energetic particles in the heliosphere, but also as a measure of solar activity. However, the validity of the modulation potential, which utilizes the force-field methodology, is uncertain for shorter timescales, and often the estimates are only monthly or yearly.

Recently, an updated estimation of the modulation potential was done at a daily time resolution by utilizing neutron monitor (NM) measurements from 10 stations. We have now analysed the daily version and compared it (via a LIS model) to the variation of the daily GCR energy spectrum (for rigidities 1 to 100 GV) measured by the AMS-02 instrument in the ISS. We find that overall, the daily modulation potential works well for estimating daily count rates at different energies. The correspondence is lowest for the low energy bins, where we see an excess of particles, which seems to follow the solar cycle. For rigidities around 4-13 GV, we can see a very clear match, letting us estimate daily count rates for different energy bins with a few per cent accuracy. For higher energies, the noise background of the measurements masks the underlying variation.

The result is very interesting and promising for the feasibility of using the modulation potential estimates for shorter time scales. This will lead to a better understanding of the variability of the overall modulation and the possibility of utilizing and combining NM and spacecraft measurements. The results will be useful in space climate (e.g. long-term solar variation induced from cosmogenic isotopes) and space weather (e.g. CME's/Forbush decreases, CIR's, Flares/GLE's) research. Future work with additional datasets and analysis of the different LIS models is planned.

How to cite: Väisänen, P., Bertucci, B., Tomassetti, N., Orcinha, M., Duranti, M., and Usoskin, I.: Daily heliospheric modulation potential (V23) and modelled GCR dataset compared to space measurements of the GCR energy spectrum., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5753, https://doi.org/10.5194/egusphere-egu24-5753, 2024.

EGU24-6034 | Orals | ST1.5 | Highlight

A new scenario for widespread solar energetic particle events based on multi-spacecraft observations of the 13 March 2023 event 

Nina Dresing, Immanuel Jebaraj, Erika Palmerio, Christian Palmroos, Christian Cohen, Grant Mitchell, Christina Lee, Wenwen Wei, Eleanna Asvestari, Manon Jarry, Gabriel Muro, Laura Rodríguz-García, and Nicola Wijsen

We report on multi-spacecraft measurements of a solar energetic particle (SEP) event that occurred on 13 March 2023. The Parker Solar Probe (PSP) mission was situated on the far side of the Sun as seen from Earth at a radial distance of only 49 solar radii and observed a very strong event including the associated CME and its shock passing over the spacecraft only four hours after the solar eruption. Solar Orbiter, BepiColombo, STEREO A, near-Earth spacecraft, and MAVEN at Mars were all situated within 50 degrees in longitude, and observed the event as well, proving its widespread character. Clear signatures of shock-driven energetic storm particle events were present at Solar Orbiter, STEREO A, and near-Earth spacecraft suggesting that the interplanetary CME-driven shock had a longitudinal extent of about 160 degrees. However, the solar event was accompanied by a series of pre-event CMEs and comparison with ENLIL simulation results suggest that the ESP events were associated with shocks driven by other CMEs. This scenario of particle re-acceleration at different pre-event-associated shocks, provides a new scenario for the generation of widespread SEP events. 

How to cite: Dresing, N., Jebaraj, I., Palmerio, E., Palmroos, C., Cohen, C., Mitchell, G., Lee, C., Wei, W., Asvestari, E., Jarry, M., Muro, G., Rodríguz-García, L., and Wijsen, N.: A new scenario for widespread solar energetic particle events based on multi-spacecraft observations of the 13 March 2023 event, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6034, https://doi.org/10.5194/egusphere-egu24-6034, 2024.

EGU24-6092 | Posters on site | ST1.5

The solar cycle 25 multi-spacecraft solar energetic particle event catalog of the SERPENTINE project 

Nina Dresing and the SERPENTINE SEP Catalog Team

We present a new multi-spacecraft SEP event catalog for events observed in solar cycle 25. Observations from five different viewpoints are utilized, which are provided by Solar Orbiter, Parker Solar Probe, STEREO A, BepiColombo, and the near-Earth spacecraft Wind and SOHO. The catalog is an output of the SERPENTINE project, funded through the European Union’s Horizon 2020 framework programme. We provide key SEP parameters for > 25 MeV protons, > 1 MeV electrons, and ∼100 keV electrons. Furthermore, basic parameters of the associated flare and type-II radio burst are listed, as well as the coordinates of the observer and solar source locations.

An event is included in the catalog if at least two spacecraft detect a significant proton event with energies > 25 MeV. SEP onset times are determined using the Poisson-CUSUM method. SEP peak times and intensities refer to the global intensity maximum. If different viewing directions are available, we use the one with the earliest onset for the onset determination and the one with the highest peak intensity for the peak identification. We furthermore aim at using the highest possible time resolution. Therefore, time averaging of the SEP intensity data is only applied if necessary to determine clean event onsets and peaks. 

Associated flares were identified using observations from near Earth and Solar Orbiter. Associated type II bursts were determined from ground-based observations in the metric frequency range and from spacecraft observations in the decametric range.

The current version of the catalog contains 45 multi-spacecraft events observed in the period from Nov 2020 until May 2023, of which 13 were widespread events and four were classified as narrow-spread events. Using X-ray observations by GOES/XRS and Solar Orbiter/STIX we were able to identify the associated flare in all but four events. Using ground-based and spacecraft radio observations we found an associated type-II radio burst for 40 events. In total the catalog contains 141 single event observations out of which 18 (39) have been observed at radial distances below 0.6 AU (0.8 AU). 

We acknowledge funding by the European Union’s Horizon 2020 research and innovation program under grant agreement No. 101004159 (SERPENTINE).   

How to cite: Dresing, N. and the SERPENTINE SEP Catalog Team: The solar cycle 25 multi-spacecraft solar energetic particle event catalog of the SERPENTINE project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6092, https://doi.org/10.5194/egusphere-egu24-6092, 2024.

EGU24-6131 | ECS | Orals | ST1.5

The circumsolar solar energetic particle event on 2022 January 2022, particle spread within and outside a magnetic cloud 

Laura Rodríguez-García, Raúl Gómez-Herrero, Nina Dresing, Laura A. Balmaceda, Erika Palmerio, Francisco Espinosa Lara, Athanasios Kouloumvakos, Immanuel Jebarah, Christian Palmroos, Timo Laitinen, Christina Lee, Christina Cohen, Annamaria Fedeli, Ignacio Cernuda, Mario Roco, Olga Malandraki, and Javier Rodríguez-Pacheco

On 2022 January 20, the Energetic Particle Detector on board Solar Orbiter detected a solar energetic particle (SEP) event showing unusual sunward-directed fluxes. Near-Earth spacecraft separated by 17° in longitude from Solar Orbiter measured classic antisunward-directed fluxes. Parker Solar Probe and MAVEN, separated by 130° and 216° respectively from Solar Orbiter, observed the particle event as well, suggesting a widespread event of nearly 360° in the heliosphere. The SEP event was associated with an M5-class X-ray flare and a CME with a speed of 1400 km/s. The energetic particles reached 3 MeV and 100 MeV energies for electrons and protons, respectively.

The aim of this study is to disentangle how the particles are able to spread throughout the heliosphere and how the local heliospheric conditions affect the acceleration and transport of the particles at different spacecraft locations. This work presents the observations and analyses that lead to a scenario in which the solar source injected energetic particles into the solar wind and within a preceding interplanetary coronal mass ejection (ICME) that was already present in the heliosphere at the time of the SEP event onset. In particular, Solar Orbiter measured the particles injected along the longest leg of an ICME still connected to the Sun at the time of the particle release.

How to cite: Rodríguez-García, L., Gómez-Herrero, R., Dresing, N., Balmaceda, L. A., Palmerio, E., Espinosa Lara, F., Kouloumvakos, A., Jebarah, I., Palmroos, C., Laitinen, T., Lee, C., Cohen, C., Fedeli, A., Cernuda, I., Roco, M., Malandraki, O., and Rodríguez-Pacheco, J.: The circumsolar solar energetic particle event on 2022 January 2022, particle spread within and outside a magnetic cloud, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6131, https://doi.org/10.5194/egusphere-egu24-6131, 2024.

EGU24-6233 | Posters on site | ST1.5

Statistical study of multi-spacecraft events and shocks observed in solar cycle 25 

Yulia Kartavykh, Bernd Heber, Robert F. Wimmer-Schweingruber, Nina Dresing, Domenico Trotta, Alexander Kollhoff, Hendrik Droege, Andreas Klassen, Emilia Kilpua, Jan Gieseler, Wolfgang Droege, Raul Gomez-Herrero, Francisco Espinosa Lara, Laura Rodriguez-Garcia, Javier Rodríguez-Pacheco, and Rami Vainio

Predictions of the intensities of solar particle events are often fraught with uncertainties. Insufficient knowledge and understanding of the solar sources of the particles, and the conditions in the corona and in the inner heliosphere, as well as magnetic connectivity, have been limiting factors in making further progress.
This presentation covers a study done by one of the Work Packages of the SERPENTINE project, and is based on the analysis of lists prepared by two other work packages of the same project, and logically consists of two parts.
In the first part we performed a statistical analysis of a list of 45 multi-spacecraft events in solar cycle 25 observed by five spacecraft located in the inner Heliosphere (Solar Orbiter, Parker Solar Probe, Stereo A, Bepi Colombo), and one located at 1 AU close to the Earth (SOHO or Wind). The list, while prepared with a focus on the detection of protons above 25 MeV by two or more spacecraft, contains also information about electron observations around 100 keV and 1 MeV, respectively.  Aiming to investigate the processes which are responsible for spreading energetic particles in longitude and latitude, and to estimate the importance of perpendicular diffusion in the latitudinal direction, we considered, together with other parameters, not only the longitudinal distances to the source, but also the differences in the total angle. In this part of our study we used methods such as correlation analysis and principal component analysis, and applied them to the list as a whole, as well as to different types of events. For example, we found that in the case of narrow-spread events perpendicular diffusion is sufficient to explain the spreading of particles from the solar source into the heliosphere, while in the case of wide-spread events an additional acceleration source is needed. We also evaluated the role of the speeds and sizes of the associated coronal mass ejections, as well as features of EUV waves appearing in the events, and relate different types of microwave (radio) emission to different groups of events.
In the second part of this work we performed a statistical analysis of a list of 61 interplanetary shocks, observed by Solar Orbiter.  By using a superposed epoch analysis, we built a statistical picture of ion time profiles around the shock front in several energy ranges. We also investigated which shock parameters are more important for particle energization by propagating interplanetary shocks, particularly in the case of an overlap in these lists.

This study has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 101004159 (SERPENTINE).

How to cite: Kartavykh, Y., Heber, B., Wimmer-Schweingruber, R. F., Dresing, N., Trotta, D., Kollhoff, A., Droege, H., Klassen, A., Kilpua, E., Gieseler, J., Droege, W., Gomez-Herrero, R., Espinosa Lara, F., Rodriguez-Garcia, L., Rodríguez-Pacheco, J., and Vainio, R.: Statistical study of multi-spacecraft events and shocks observed in solar cycle 25, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6233, https://doi.org/10.5194/egusphere-egu24-6233, 2024.

EGU24-6382 | Posters on site | ST1.5

Solar Energetic Particle Analysis Platform for the Inner Heliosphere (SERPENTINE): Summary of Project Results 

Rami Vainio, Nina Dresing, Jan Gieseler, Christian Palmroos, Emilia Kilpua, Daniel Price, Domenico Trotta, Timothy Horbury, Yulia Kartavykh, Bernd Heber, Robert Wimmer-Schweingruber, Illya Plotnikov, Raúl Gómez-Herrero, and Javier Rodriguez-Pacheco

Solar Energetic Particle Analysis Platform for the Inner Heliosphere (SERPENTINE) is a 42-months-long EU/H2020 project that started in January 2021 and focuses on the physics of Solar Energetic Particle (SEP) acceleration and transport. The project (see https://serpentine-h2020.eu) provides answers for three science questions:

(Q1) what are the primary reasons for widespread SEP events;

(Q2) what are the mechanisms responsible for acceleration ions from suprathermal to near-relativistic energies in coronal and interplanetary shocks; and

(Q3) what is the role of shocks in the acceleration of electrons in SEP events.

SERPENTINE makes use of the present capabilities provided by inner heliospheric missions such as Solar Orbiter, Parker Solar Probe and BepiColombo. In addition to the scientific objectives, the project develops and releases to the community a large number of analysis tools to facilitate the interpretation of observations. Also event catalogs and high-level datasets are produced and distributed.

We will give a summary of the results of the project. Some of the science highlights include the several identified causes of widespread events related to both sources and transport (Q1), the role of local and averaged properties of shocks in ion acceleration (Q2), and the observational evidence of shocks as the primary accelerators of MeV electrons in gradual SEP events (Q3).

How to cite: Vainio, R., Dresing, N., Gieseler, J., Palmroos, C., Kilpua, E., Price, D., Trotta, D., Horbury, T., Kartavykh, Y., Heber, B., Wimmer-Schweingruber, R., Plotnikov, I., Gómez-Herrero, R., and Rodriguez-Pacheco, J.: Solar Energetic Particle Analysis Platform for the Inner Heliosphere (SERPENTINE): Summary of Project Results, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6382, https://doi.org/10.5194/egusphere-egu24-6382, 2024.

EGU24-6854 | ECS | Posters on site | ST1.5

Modelling energetic particle transport with the PARADISE code 

Edin Husidic, Nicolas Wijsen, Stefaan Poedts, and Rami Vainio

Numerical tools for realistic modelling of energetic processes in the heliosphere, with the prospect of forecasting space weather, are in high demand. Of particular interest are solar energetic particles (SEPs), comprising high-energy charged particles linked to solar eruptive phenomena. During large SEP events, protons can be accelerated to energies ranging from tens of MeV up to a few GeV per nucleon, posing a dangerous threat to astronauts and spacecraft. While the precise acceleration mechanism behind SEP events is still an open challenge, observations indicate that the intensities of SEPs are highly influenced by the large-scale solar wind configuration. Transient structures such as coronal mass ejections (CMEs) or stream interaction regions (SIRs) perturb the interplanetary (IP) magnetic field, ultimately altering the transport of SEPs. In this context, we share recent results obtained with the energetic particle transport code PARADISE. By utilising realistic and complex solar wind configurations derived from magnetohydrodynamic (MHD) models such as EUHFORIA and the MPI-AMRVAC-based model Icarus, the code solves the focused transport equation in a stochastic manner to obtain spatio-temporal intensity distributions of SEPs in the inner heliosphere. Our studies focus on particle acceleration at IP shocks related to CMEs and SIRs.

How to cite: Husidic, E., Wijsen, N., Poedts, S., and Vainio, R.: Modelling energetic particle transport with the PARADISE code, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6854, https://doi.org/10.5194/egusphere-egu24-6854, 2024.

EGU24-7297 | ECS | Posters virtual | ST1.5

Simulation for the calibration of radiation data acquired by Solar Particle Monitor/MMO 

Gaku Kinoshita, Haruka Ueno, Go Murakami, and Kazuo Yoshioka

    The exploration of the inner heliosphere has been limited by large gravitational potential differences. Consequently, the propagation processes of solar ejecta such as Interplanetary Coronal Mass Ejections (ICMEs) and Solar Energetic Particles (SEPs) are somewhat problematic. Recent orbital engineering developments and other advancements have enabled the deployment of multiple probes, such as BepiColombo and Solar Orbiter. This has provided a unique opportunity for multi-point observations of solar eruptions, allowing for the tracking of their radial and longitudinal evolution. 

    This study focuses on radiation data acquired by “Solar Particle Monitor (SPM)” onboard BepiColombo for solar physics. SPM is the housekeeping instrument, particularly more suited for highly energetic particles such as Solar Energetic Particles (SEP) and Galactic Cosmic Ray (GCR) than other instruments. However, it provides only time-series data of count rates and deposited energies. To extract valuable information about the incident charged particles, including their type, number, energy, and direction, a radiation simulation toolkit Geant4 (Allison et al., 2016) is employed.

    The mass SPM model was defined in the model space, incorporating an aluminum shield to estimate radiation shielding effects from surrounding equipment and walls of spacecraft. The thickness of the shield in each direction is determined by comparing SPM measurements with simulation results, identifying the combination of thicknesses that aligns most closely with observed trends. The study also reproduces the electron flux during BepiColombo's Earth swing-by in 2020 using the AE9 radiation model (Ginet et al., 2013), comparing the simulated results with actual measurements to determine effective shield thicknesses. Additionally, the method proposed by Park et al. (2021), utilizing transformation matrices to derive incident particle energy spectra from observed spectra, is applied.

    Our research extends the analysis to the recovery time constants of Forbush Decreases, resulting from ICME shielding GCR which the spacecraft encountered in 2022. The study aims to analyze the structural changes induced by the interaction between ICMEs and solar wind during their propagation. Future applications of the analysis are planned for Solar Energetic Particle (SEP) studies, contributing to the understanding of SEP propagation processes through multi-point observations.

    The implications of the results are significant, especially considering the predicted peak of the 11-year solar activity cycle in 2025. BepiColombo, having already captured numerous phenomena, necessitates further analysis using the established calibration method. The study underscores the potential applicability of housekeeping devices commonly equipped on spacecraft for scientific observations. If applied to other probes, similar methods not only expand the scope of scientific observations but also contribute to the growth of the solar observation network within the heliosphere.

How to cite: Kinoshita, G., Ueno, H., Murakami, G., and Yoshioka, K.: Simulation for the calibration of radiation data acquired by Solar Particle Monitor/MMO, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7297, https://doi.org/10.5194/egusphere-egu24-7297, 2024.

EGU24-7917 | ECS | Posters on site | ST1.5

Electron and proton peak intensities in solar energetic particle events 

Ghulam Farwa, Nina Dresing, Jan Gieseler, Christian Palmroos, Laura Vuorinen, Stefan Jensen, Bernd Heber, Patrick Kühl, Ian Richardson, Saku Valkila, and Rami Vainio

   Solar energetic particle (SEP) events are major outbursts of energetic charged particle radiation from the Sun. These events are related to solar flares and fast coronal mass ejections (CMEs). Flares are presumed to accelerate particles in magnetic reconnection processes, whereas fast (speeds > 1000 km s–1) CMEs drive shock waves through the corona that are known to be able to accelerate particles. Electron acceleration has traditionally been ascribed to reconnection in flares whereas proton acceleration is believed to be efficient in CME-driven shocks. Recent observational evidence [1], however, suggests that shocks may be important in electron acceleration as well. Almost all major eruptions are related to both flares and CMEs so the association of the accelerated particles to these eruptive phenomena is often subject to debate. Using novel spacecraft observations of strong SEP events detected in solar cycle 25, we aim at identifying the parent acceleration region of the observed electron and proton events.

We have analyzed a set of 45 SEP events between Nov 2020 and May 2023 using data from multiple spacecraft including Solar Orbiter, near-Earth spacecraft (SOHO and Wind), STEREO-A and BepiColombo. We make use of peak intensities of >25-MeV protons and ~100 keV and ~1 MeV electrons and perform correlation studies of these peak intensities with each other as well as with the associated flare intensity. We separate the events into those that are well-connected (angular separation ≤ 35°) or poorly-connected (angular separation > 35°) to the flare by the interplanetary magnetic field.

We find significant correlations between electron and proton peak intensities. While events detected by poorly-connected observers show a single population of events, consistent with the idea that these particles are all accelerated by the spatially-extended CME-driven shock, events observed in well-connected regions show two populations: One population has higher proton peak intensities that correlate with electron peak intensities similarly to the poorly-connected events. These are most likely shock associated.  The other population has low proton intensities that are less well correlated with electron peak intensities. This population is suggested to show a dominant contribution of the flare.

References:
[1] Dresing, N. Kouloumvakos, A., Vainio, R., Rouillard, A., Astrophys. J. Lett., 925, L2

 

How to cite: Farwa, G., Dresing, N., Gieseler, J., Palmroos, C., Vuorinen, L., Jensen, S., Heber, B., Kühl, P., Richardson, I., Valkila, S., and Vainio, R.: Electron and proton peak intensities in solar energetic particle events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7917, https://doi.org/10.5194/egusphere-egu24-7917, 2024.

Solar energetic particle (SEP) events are increases of ions and electrons caused
by solar activity namely flares and coronal mass ejections. While the most
energetic ion population is well studied, SEP events accelerating electrons above
20 MeV have only been reported from measurements by ISEE III in the 1980’s
and the Kiel Electron Telescope (KET).
The KET aboard Ulysses launched in 1990 and measured the electron flux in
the energy range from 4 MeV to above 6 GeV. Here we report on observations
of ultra-relativistic electrons and show spectra of electron events during solar
cycle 22 and 23 until the end of 2008. The maximum electron energy exceeded
100 MeV during the August 16, 2001 SEP event.
This study has received funding from the European Union’s Horizon 2020
research and innovation programme under grant agreement No. 101004159
(SPEARHEAD).

How to cite: Köberle, M., Heber, B., and Jöhnk, C.: Measurements of ultra-relativistic electrons during solar energetic particle events - Results from the Ulysses Kiel Electron Telescope, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8445, https://doi.org/10.5194/egusphere-egu24-8445, 2024.

EGU24-8560 | ECS | Orals | ST1.5

Statistical analysis of first-order anisotropy in multi-spacecraft solar energetic particle events of the solar cycle 25 

Laura Vuorinen, Nina Dresing, Maximilian Brüdern, Jan Gieseler, and Christian Palmroos

Solar energetic particles (SEPs) are high-energy charged particles associated with solar eruptions. They constitute a major component of the heliospheric radiation environment, presenting a key space weather hazard. SEPs are accelerated at solar flares and at shock waves driven by coronal mass ejections, but the relative importance of these sources is not fully understood — particularly in the case of electrons. In addition to the underlying acceleration mechanisms, the evolution of a SEP event is highly influenced by transport in the interplanetary space. Anisotropy of the intensity-pitch-angle distribution is an important quantity that can be used to infer information about these effects, especially when multi-spacecraft observations are available. We investigate the first-order anisotropy of electrons and protons in SEP events of the solar cycle 25 using observations from multiple spacecraft of the inner-heliospheric fleet. We pay special attention to the methodology of determining anisotropy and its uncertainty from four-sector telescope (SOLO EPD/EPT and STEREO SEPT) measurements, in which pitch-angle coverage of the telescopes significantly influences the observed anisotropy. We present our methodology and the preliminary results of our statistical analysis, where we study the peaks and durations of anisotropic periods in high-energy electron and proton events as a function of particle energy and longitudinal separation.

How to cite: Vuorinen, L., Dresing, N., Brüdern, M., Gieseler, J., and Palmroos, C.: Statistical analysis of first-order anisotropy in multi-spacecraft solar energetic particle events of the solar cycle 25, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8560, https://doi.org/10.5194/egusphere-egu24-8560, 2024.

EGU24-8772 | ECS | Orals | ST1.5

Energy spectra of 300 keV to 1 MeV electrons from the SOHO Electron Proton Helium INstrument (EPHIN) 

Stefan Jensen, Bernd Heber, Malte Hörlöck, Alexander Kollhoff, Patrick Kühl, and Holger Sierks

The origins of energetic electrons with energies ranging from a few tens of keV to tens of MeV in the inner heliosphere are manifold. They include Galactic Cosmic Rays, Jovian electrons as well as sporadic Solar Energetic Electron (SEE) events. Their energy spectra provide insights into the acceleration at the source and transport processes in the heliosphere.

The SOlar and Heliospheric Observatory (SOHO) was launched in December 1995 with the Electron Proton Helium INstrument (EPHIN) measuring electrons from 150 keV to several MeV. However, its measuring capability was reduced due to the loss of two detectors in 1997 and 2017, respectively. Thus from 2017 onwards only two electron channels, one in the range from 300 keV to one MeV and one “integral channel” that measures between 300 keV and 10 MeV.

In this contribution we present a new data product for electron spectra based on the onboard histograms. This data product has the advantage of providing the total energy loss in the first two detectors with good statistics compromising energy loss determination via PHA data and counting statistics of the single channel. Using the so-called bow-tie method we were able to derive several energy channels between 300 keV and about 1 MeV. We present first results and compare them with instruments from other missions.

The SOHO/EPHIN project is supported under Grant 50 OC 2102 by the German Bundesministerium für Wirtschaft through the Deutsches Zentrum für Luft- und Raumfahrt (DLR). This study has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 101004159 (SERPENTINE).

 

 

 

How to cite: Jensen, S., Heber, B., Hörlöck, M., Kollhoff, A., Kühl, P., and Sierks, H.: Energy spectra of 300 keV to 1 MeV electrons from the SOHO Electron Proton Helium INstrument (EPHIN), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8772, https://doi.org/10.5194/egusphere-egu24-8772, 2024.

EGU24-8897 | Posters on site | ST1.5

Turbulent structure of CME-driven sheath regions and their role as energizing charged particles in interplanetary space 

Emilia Kilpua, Simon Good, Rami Vainio, Matti Ala-Lahti, Nina Dresing, Jan Gieseler, Venla Koikkalainen, Adnane Osmane, Julia Ruohotie, Juska Soljento, Domenico Trotta, Christina Cohen, Timothy Horbury, and Stuart Bale
Fast Coronal Mass Ejections (CMEs) gather compressed and heated solar wind ahead of them to for turbulent sheath regions. In this presentation we will first demonstrate with recent examples (using e.g. Parker Solar Probe and Solar Orbiter measurements) and the results from a statistical analysis (the ACE spacecraft data) that CME-driven sheath regions can significantly contribute to the acceleration of charged particles in interplanetary space, independent from the effect of the leading shock wave.  Then, we will present the key characteristics of sheath regions, e.g., variations of magnetic fied fluctuation and key turbulent properties across the sheath, that can have the key importance for the particle energization.  

 

How to cite: Kilpua, E., Good, S., Vainio, R., Ala-Lahti, M., Dresing, N., Gieseler, J., Koikkalainen, V., Osmane, A., Ruohotie, J., Soljento, J., Trotta, D., Cohen, C., Horbury, T., and Bale, S.: Turbulent structure of CME-driven sheath regions and their role as energizing charged particles in interplanetary space, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8897, https://doi.org/10.5194/egusphere-egu24-8897, 2024.

EGU24-9560 | ECS | Posters on site | ST1.5

Solar Energetic Proton forecasting with REleASE during STEREO-A’s flyby of Earth 

Henrik Dröge, Bernd Heber, Alexander Kollhoff, Patrick Kühl, Olga Malandraki, and Arik Posner

Solar Energetic Particle (SEP) events can pose a significant radiation hazard for human and robotic space exploration activities. Therefore SEP forecasting systems are needed to support operations. The REleASE system (A. Posner, 2007) utilizes the fact that near relativistic electrons (1 MeV electrons have 94% of the speed of light) travel faster than ions (30 MeV protons have 25% of the speed of light) and are always present in hazardous SEP events. Their early arrival can be used to forecast the expected proton flux. Originally REleASE uses real time data from SOHO/EPHIN near Earth. Since the instrument is aging we recently adapted the method to STEREO-A/HET and used the period from June to November 2023 when STEREO-A passed the Earth to compare the REleASE forecasts from the different instruments.

This study has received funding from the National Aeronautics and Space Administration under grant agreement No. TXS0150642 (HESPERIA RELEASE).

How to cite: Dröge, H., Heber, B., Kollhoff, A., Kühl, P., Malandraki, O., and Posner, A.: Solar Energetic Proton forecasting with REleASE during STEREO-A’s flyby of Earth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9560, https://doi.org/10.5194/egusphere-egu24-9560, 2024.

EGU24-9954 | ECS | Orals | ST1.5

Development of a balloon-borne radioactivity detector for space weather measurements 

Justin Tabbett and Karen Aplin

Measurement of space weather is key to understanding, preventing, and mitigating the adverse effects of space weather events. Ground-based detectors and satellite sensors provide coverage of energetic particles in their respective domains, however, there remains scope for intermediary devices and instrumentation.

We present a novel energetic particle detector which has undergone development and deployment on radiosonde systems. The small form-factor and light weight instrument is composed of a CsI(Tl) scintillator coupled to a PiN photodiode and is capable of count rate and energy discrimination. Recent energy calibrations suggest the instrument is sensitive to a range of energies from 30 keV to 9.4 MeV. The microscintillator detector is therefore an ideal instrument for space weather investigations.

During previous flights, the microscintillator detector responded to low energy particles in the stratosphere, particularly observing energetic electron precipitation events. Recent research however has focussed on understanding and improving the detector performance at temperatures comparable to the atmospheric environment, and modifying the internal microcontroller system for interfacing with the new industry standard Vaisala RS41 radiosonde system.

We present the low temperature (0 °C to -50 °C) response of the detector to terrestrial background radiation, and progress in interfacing with the new radiosonde system, both obtained in a controlled laboratory setting. Future deployments of the detector are planned over the coming year as we approach solar maximum in 2025.

How to cite: Tabbett, J. and Aplin, K.: Development of a balloon-borne radioactivity detector for space weather measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9954, https://doi.org/10.5194/egusphere-egu24-9954, 2024.

EGU24-10356 | Posters on site | ST1.5

Open-Source Analysis Platform for Solar Energetic Particles provided by SERPENTINE 

Jan Gieseler, Christian Palmroos, Nina Dresing, Athanasios Kouloumvakos, Diana E. Morosan, Daniel J. Price, Domenico Trotta, Laura Vuorinen, Aleksi Yli-Laurila, Eleanna Asvestari, Saku Valkila, and Rami Vainio

The recently expanded fleet of heliospheric spacecraft presents unique opportunities for exploring solar eruptive phenomena such as coronal mass ejections (CMEs) and solar energetic particles (SEPs) from multiple vantage points. However, the task of integrating diverse observations collected by different instruments across various spacecraft poses a notable challenge. To maximize the utilization of this data within the broader scientific community, the EU Horizon 2020 project SERPENTINE aims to offer a versatile array of tools. These tools, provided as open-source Python Jupyter Notebooks, cater to scientists with limited programming expertise. Alongside comprehensive examples illustrating the utilization of the multi-spacecraft spatial setup and solar magnetic connection plotter Solar-MACH, an analysis platform for studying the energetic particle component of the in-situ observations of SEP events has been developed. This analysis platform comprises visualization tools (e.g., energetic particle time series or dynamic spectra) and analytical software capable of automatically determining SEP onsets or estimating particle path length and injection time via a time-shift analysis approach. Our poster will provide an overview of the available toolkit and instructions on its utilization, which can be seamlessly accessed on SERPENTINE’s dedicated JupyterHub server in the cloud.

This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101004159 (SERPENTINE).

How to cite: Gieseler, J., Palmroos, C., Dresing, N., Kouloumvakos, A., Morosan, D. E., Price, D. J., Trotta, D., Vuorinen, L., Yli-Laurila, A., Asvestari, E., Valkila, S., and Vainio, R.: Open-Source Analysis Platform for Solar Energetic Particles provided by SERPENTINE, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10356, https://doi.org/10.5194/egusphere-egu24-10356, 2024.

EGU24-10365 | ECS | Posters on site | ST1.5

A New Method for Finding SEP Event Onset Times and Evaluating Their Uncertainty: Poisson-CUSUM-bootstrap Hybrid Method 

Christian Palmroos, Nina Dresing, and Jan Gieseler

Solar energetic particles (SEPs) are highly energetic charged particles that have their origin of acceleration in strong space-weather driving phenomena that the Sun produces, e.g., solar flares and coronal mass ejections. These particles pose a radiation hazard to both technological equipment and living organisms in space, which is why the nature of these events is an important subject of study in the modern age where space technology is being applied more and more every day.

An SEP event is the result of a burst of SEPs arriving at an observer. Especially the onset time of an SEP event at varying energies is a key piece of information in relating the in-situ particle measurements to the remote-sensing observations of solar eruptions. Accurate knowledge of the onset time is an indispensable requirement for identifying the acceleration mechanisms and the source of the energetic particles. What traditional methods lack, however, is the assessment of the uncertainty related to the onset time.

Our method employs a unique combination of a statistical quality control scheme, Poisson-CUSUM, coupled with statistical bootstrapping. By choosing random samples from the background intensity preceding an SEP event and varying the integration time of the data, the method is able to produce a set of distributions of possible onset times. From this set of distributions we extract the most probable onset time and uncertainty intervals relating to this set of distributions. 

The uncertainty of onset times in a range of different energies is also in a direct connection to the uncertainty of a derived path length and inferred solar injection time of the particles, two extremely important pieces of information that velocity dispersion analysis yields, which is yet another motivator behind developing the method presented here

This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101004159 (SERPENTINE).

 

How to cite: Palmroos, C., Dresing, N., and Gieseler, J.: A New Method for Finding SEP Event Onset Times and Evaluating Their Uncertainty: Poisson-CUSUM-bootstrap Hybrid Method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10365, https://doi.org/10.5194/egusphere-egu24-10365, 2024.

EGU24-10520 | Posters on site | ST1.5

A Hydrogenated amorphous silicon detector for Space Weather Applications 

Catia Grimani and Federico Sabbatini and the HASPIDE Collaboration

The fleet of present and future space missions aimed at studying the Sun and the solar-terrestrial relationships carry
particle detectors, among other instruments. The monitoring of intense solar activity and solar energetic particle (SEP)
events provide fundamental contributions to Space Weather and Space Weather science. Unfortunately, very few of these instruments are optimized
for the  measurement of the proton differential flux above 200 MeV/n. We show that by increasing this minimum energy to 400-600 MeV/n it is possible to infer the trend of the differential flux with small uncertainties up to GeV energies, while this is not the case if the measurements are limited  to 200 MeV/n. To this purpose, we report on the characteristics of a single instrument meant for the detection of  solar flares and high-energy particles, galactic magnetar activity and gamma-ray burst observations. The instrument is based on hydrogenated amorphous silicon as a sensitive material that presents an excellent radiation hardness and finds application for particle beam characterization and medical purposes.

 

How to cite: Grimani, C. and Sabbatini, F. and the HASPIDE Collaboration: A Hydrogenated amorphous silicon detector for Space Weather Applications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10520, https://doi.org/10.5194/egusphere-egu24-10520, 2024.

EGU24-11246 | ECS | Posters on site | ST1.5

Effects of adiabatic focusing in 1D coronal shock acceleration 

Lidiya Annie John, Seve Nyberg, Laura Vuorinen, Rami Vainio, Alexandr Afanasiev, Stefaan Poedts, and Nicolas Wijsen

Solar energetic particles (SEPs) pose a significant radiation hazard to both technologies and human beings in space. SEPs undergo acceleration to higher energy levels through various eruptive phenomena, specifically, solar flares and coronal mass ejections (CMEs). Based on these sources, SEP events can be classified as impulsive and gradual events, respectively, although more recent findings showed that large SEP events contain both sources (solar flare reconnection and CME shock waves). Greater risk is attributed to CME shock-driven events due to their larger quantity of accelerated particles and longer duration. In such SEP events, solar particles are considered to be accelerated by the diffusive shock acceleration process in CME-driven coronal shocks. The role of inhomogeneous magnetic field-induced adiabatic focusing in the one dimensional diffusive shock acceleration (DSA) process is not effectively studied. Hence, in our numerical study, we aim to understand the effects of adiabatic focusing on coronal shock acceleration and to investigate whether a free escape boundary could yield similar results in the absence of focusing. This involves employing two models: one featuring a finite and homogeneous upstream region, eliminating focusing, and another one incorporating a weakening magnetic field, facilitating particle escape through the focusing effect. We present the results from a one-dimensional oblique shock model with a mean free path similar to  Bell’s theory (Bell, 1978) using Monte Carlo simulations. This research is funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 955620.

References 

Bell, A. R. 1978, MNRAS, 182, 147

How to cite: Annie John, L., Nyberg, S., Vuorinen, L., Vainio, R., Afanasiev, A., Poedts, S., and Wijsen, N.: Effects of adiabatic focusing in 1D coronal shock acceleration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11246, https://doi.org/10.5194/egusphere-egu24-11246, 2024.

EGU24-12767 | Posters on site | ST1.5

The SERPENTINE Project Data Center 

Raúl Gómez-Herrero, Francisco Espinosa Lara, Javier Rodríguez-Pacheco, Laura Rodríguez-García, Ignacio Cernuda, Mario Roco, Rami Vainio, Nina Dresing, Yulia Kartavykh, Emilia K.J. Kilpua, Domenico Trotta, Illya Plotnikov, Daniel Price, Bernd Heber, Timothy S. Horbury, and Robert F. Wimmer-Schweingruber and the The SERPENTINE Team

Since its start in 2021, the Solar EneRgetic ParticlE aNalysis plaTform for the INner hEliosphere (SERPENTINE) Project funded by EU H2020 program is using multi-spacecraft observations to investigate the origin of Solar Energetic Particles (SEPs) and providing new tools and datasets for the heliophysics community. SERPENTINE distributes new catalogues covering past and recent multipoint observations of SEP events, as well as their associated coronal mass ejections and interplanetary shocks. New SEP-related high-level data products from BepiColombo and Solar Orbiter missions, with added scientific value will be also provided in the near future. In this work, we summarize the structure, contents, and functionalities of the SERPENTINE Project Data Center (https://data.serpentine-h2020.eu/), a web-based interface providing open access to the various catalogues and high-level data products resulting from the project.

This research has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101004159 (SERPENTINE).

How to cite: Gómez-Herrero, R., Espinosa Lara, F., Rodríguez-Pacheco, J., Rodríguez-García, L., Cernuda, I., Roco, M., Vainio, R., Dresing, N., Kartavykh, Y., Kilpua, E. K. J., Trotta, D., Plotnikov, I., Price, D., Heber, B., Horbury, T. S., and Wimmer-Schweingruber, R. F. and the The SERPENTINE Team: The SERPENTINE Project Data Center, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12767, https://doi.org/10.5194/egusphere-egu24-12767, 2024.

EGU24-13125 | Posters on site | ST1.5

The Canadian SWeeping Energetic Particle Telescope (SWEPT): Steerable Energy and Pitch Angle Resolved Energetic Particle Measurements on the Lunar Gateway 

Robert Fedosejevs, Ian Mann, Henry Tiedje, Louis Ozeke, Kai Gan, Bo Yu, David Barona, Neil Rowlands, Dwight Caldwell, Ken Smith, and Muhammad Amjad

The Canadian SWeeping Energetic Particle Telescope (SWEPT) targets an assessment of the pitch angle dependence of particular space radiation, and will address and characterize the energy and directional dependence of this space radiation in the lunar environment. The project focuses on an assessment of the fundamental plasma processes which accelerate the particles to create this severe radiation hazard for astronauts in deep space, and assess radiation risk mitigation. By using an innovative sweeping look direction to determine the angular and energy dependence of the radiation on the Lunar Gateway, the SWEPT can assess the temporally evolving solar energetic particle (SEP) radiation in the heliosphere, emitted in solar eruptions and accelerated at interplanetary shocks, as well as address the impacts of primary and secondary radiation hazards on the Lunar Gateway. The SWEPT will also contribute to the development of effective deep space radiation mitigation strategies, such as those based on the early arrival of solar energetic electrons in advanceof SEP protons for humans on the lunar surface or in the lunar vicinity.

How to cite: Fedosejevs, R., Mann, I., Tiedje, H., Ozeke, L., Gan, K., Yu, B., Barona, D., Rowlands, N., Caldwell, D., Smith, K., and Amjad, M.: The Canadian SWeeping Energetic Particle Telescope (SWEPT): Steerable Energy and Pitch Angle Resolved Energetic Particle Measurements on the Lunar Gateway, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13125, https://doi.org/10.5194/egusphere-egu24-13125, 2024.

EGU24-13567 | ECS | Orals | ST1.5

Acceleration and Release of Solar Energetic Particles Associated with a Coronal Shock on 2021 September 28 Observed by Four Spacecraft 

Bin Zhuang, Noé Lugaz, David Lario, Ryun Young Kwon, Nicolina Chrysaphi, Jonathan Niehof, Tingyu Gou, and Lulu Zhao

The main driver of the acceleration of solar energetic particles (SEPs) is believed to be shocks driven by coronal mass ejections (CMEs). Extreme ultraviolet (EUV) waves are coronal disturbances that have been interpreted as the propagating footpoint of CME-driven shocks on the solar surface. One of the key questions in SEP research is the timing of the SEP release with respect to the time when the EUV wave magnetically connects with an observer. Taking advantage of the measurements by Parker Solar Probe (PSP) and Solar Orbiter (SolO) close to the Sun, we investigate a SEP event that occurred on 2021 September 28 and was observed at four different locations by SolO, PSP, STEREO-A, and the near-Earth spacecraft. During this time, SolO, PSP, and STEREO-A shared similar nominal magnetic footpoints but were at different heliocentric distances. We find that the SEP release times estimated at these four locations were delayed compared to the times when the EUV wave intercepted the footpoints of the nominal magnetic fields connecting to each spacecraft by around 30 to 60 minutes. Combining observations in multiple wavelengths from radio to EUV wavelengths passing by white light, with a geometrical shock model based on multi-viewpoint observations, we analyze the associated shock properties, and discuss the acceleration and delayed release processes of SEPs in this event as well as the accuracy and limitations of using EUV waves to determine the SEP acceleration and release times.

How to cite: Zhuang, B., Lugaz, N., Lario, D., Kwon, R. Y., Chrysaphi, N., Niehof, J., Gou, T., and Zhao, L.: Acceleration and Release of Solar Energetic Particles Associated with a Coronal Shock on 2021 September 28 Observed by Four Spacecraft, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13567, https://doi.org/10.5194/egusphere-egu24-13567, 2024.

EGU24-14142 | Posters on site | ST1.5

Proton energy spectra of energetic storm particle events and magnetic field turbulent fluctuations nearby the associated interplanetary shocks 

Fabio Lepreti, Federica Chiappetta, Monica Laurenza, Simone Benella, and Giuseppe Consolini

Interplanetary shocks are efficient sources of accelerated particles and are often associated with high-energy proton/ion flux enhancements known as energetic storm particle (ESP) events. In situ spacecraft observations of particle fluxes near the shocks can be used to obtain energy spectra, providing very useful information for the investigation of the acceleration mechanisms. In this work we analysed the kinetic energy spectra of proton flux enhancements associated with ESP events observed by various spacecraft. ESP events associated with diverse shock conditions and geometries (e.g. quasi-perpendicular and quasi-parallel) were investigated. In addition, some of the events occurred during intervals in which Solar Energetic Particle (SEP) events were also ongoing, providing a background of pre-accelerated particles. The analysis of the shape of the observed spectra was used to identify which are the most plausible acceleration mechanisms at work. The turbulent magnetic field fluctuations upstream and downstream of the shocks were also studied to the aim of obtaining information about their possible role in particle acceleration.

This research has been carried out in the framework of the CAESAR (Comprehensive spAce wEather Studies for the ASPIS prototype Realization) project, supported by the Italian Space Agency and the National Institute of Astrophysics through the ASI-INAF n. 2020-35-HH.0 agreement for the development of the ASPIS (ASI Space weather InfraStructure) prototype of scientific data centre for Space Weather.

How to cite: Lepreti, F., Chiappetta, F., Laurenza, M., Benella, S., and Consolini, G.: Proton energy spectra of energetic storm particle events and magnetic field turbulent fluctuations nearby the associated interplanetary shocks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14142, https://doi.org/10.5194/egusphere-egu24-14142, 2024.

EGU24-15030 | ECS | Posters on site | ST1.5

Interplanetary shocks and particle energisation in the inner heliosphere 

Domenico Trotta, Heli Hietala, Timothy S. Horbury, Rami Vainio, Nina Dresing, Andrew Dimmock, Xochitl Blanco-Cano, Yulia Kartavykh, Robert Wimmer-Schweingruber, Emilia Kilpua, Immanuel Jebaraj, Jan Gieseler, Francisco Espinosa Lara, and Raul Gomez Herrero

Interplanetary (IP) shocks are important sites of particle acceleration in the Heliosphere and can be observed in-situ utilizing spacecraft measurements. Such observations, crucial to address important aspects of energy conversion for a variety of astrophysical systems.

From this point of view, Solar Orbiter provides observations of interplanetary shocks at different locations in the inner heliosphere with unprecedented time and energy resolution in the suprathermal (usually above 50 keV) energy range. The general trends observed by Solar Orbiter and other spacecraft in the near-Earth environment for such shocks, highlighting their typical parameters, will be presented first. Then, the presence shock-induced wave activity in association with such shocks and their association with the presence of energetic particles will be discussed, summarizing some of the work performed in the framework of the the Solar EneRgetic ParticlE aNalysis plaTform for the INner hEliosphere (SERPENTINE) Project funded by EU H2020. Finally, particular emphasis will be devoted on the role of space/time irregularities at IP shocks and their effect on suprathermal particle production, focusing on some of the most interesting shocks observed by Solar Orbiter. 

How to cite: Trotta, D., Hietala, H., Horbury, T. S., Vainio, R., Dresing, N., Dimmock, A., Blanco-Cano, X., Kartavykh, Y., Wimmer-Schweingruber, R., Kilpua, E., Jebaraj, I., Gieseler, J., Espinosa Lara, F., and Gomez Herrero, R.: Interplanetary shocks and particle energisation in the inner heliosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15030, https://doi.org/10.5194/egusphere-egu24-15030, 2024.

EGU24-15162 | ECS | Posters on site | ST1.5

Stochastic shock drift acceleration of electrons: Monte Carlo simulations 

Seve Nyberg, Rami Vainio, Laura Vuorinen, and Alexander Afanasiev

The presence of energetic electrons in the heliosphere is associated with solar eruptions, but details of the acceleration and transport mechanisms are still unknown. We explore how electrons interact with shock waves under the assumptions of stochastic shock drift acceleration (SSDA). Consideration of the shock wave parameter space, such as shock speed, shock obliquity, shock thickness, and plasma density upstream of the shock, helps determine electron spectra and their highest energies. With suitable simulation parameters, the SSDA model is able to produce an electron beam upstream of the shock wave, a requirement for the type II radio burst seen in radio observations associated with shock waves and particle acceleration.

This presentation delves into the results of the presented model in regards to electron acceleration and transport within shock waves, contributing to our understanding of solar and interplanetary phenomena and their practical applications in space weather forecasting.

Figure: The one-dimensional stochastic shock drift acceleration Monte Carlo model geometry used to investigate electron acceleration and transport at heliospheric shock waves. 

 

How to cite: Nyberg, S., Vainio, R., Vuorinen, L., and Afanasiev, A.: Stochastic shock drift acceleration of electrons: Monte Carlo simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15162, https://doi.org/10.5194/egusphere-egu24-15162, 2024.

EGU24-15788 | Posters on site | ST1.5

RADEM on JUICE's first observations of the interplanetary radiation environment  

Wojtek Hajdas and Andre Galli and the RADEM collaboration

RADEM (Radiation Hard Electron Monitor) is a versatile detector of energetic particles designed for measurements of Jupiter's harsh radiation environment. It is one of the instruments on the ESA JUICE (Jupiter Icy Moons Explorer) mission launched on April 14th, 2023. RADEM was switched on for a short commissioning phase shortly after the spacecraft launch and since August 2023 has been carrying on observations of the interplanetary radiation environment. The instrument will be operational throughout the JUICE mission from its cruise phase to the nominal scientific segment around the giant planet and its moons. RADEM was designed to detect electrons up to 40 MeV and protons up to 250 MeV enabling for covering of the most intense and hazardous regimes of the Jupiter radiation belts. Energy distributions of both protons and electrons are unfolded using eight semi-logarithmic energy bins. It allows for measurements of the spectral shapes and dynamic changes in the radiation intensity. RADEM also contains a detector sensitive to the direction of the incoming radiation with an angular coverage of 35% of the sky. Combined spectroscopic and angular measurements will allow for more accurate studies and mapping of the radiation around Jupiter and its moons. The instrument also has a dedicated heavy-ion detector designed to measure heavy-ion linear energy transfer between 0.1 and 10 MeV/cm/mg-1. RADEM's primary purpose as a radiation monitor is to observe mission dose levels for safety concerns of the spacecraft and its scientific payload. In addition, its spectroscopic measurements in the higher energy range provide valuable extensions to other instruments from the JUICE payload. In particular, the Particle Environmental Package suite of instruments optimized for particle and ion energies up to about 1 MeV will obtain data prolongation up to about 100 MeV. RADEM operation during the cruise phase opens up a unique opportunity for conducting real-time, continuous observations of the Solar System radiation environment. It covers the current, twenty-fifth solar cycle including the solar maximum expected in 2025. With the JUICE-RADEM monitoring the radiation in the space between Venus and Mars orbits one obtains a data set useful for our future manned and unmanned explorations of these two neighboring planets. In this contribution, we will present the first RADEM observations of the interplanetary radiation environment including initial reports of detected SEPs (Solar Energetic Particles). The presented data set will cover the period since September 2023. The data will be correlated with observations from other instruments flying onboard spacecraft around the Earth or in interplanetary space such as e.g. BeppiColombo and Solar Orbiter.

 

How to cite: Hajdas, W. and Galli, A. and the RADEM collaboration: RADEM on JUICE's first observations of the interplanetary radiation environment , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15788, https://doi.org/10.5194/egusphere-egu24-15788, 2024.

EGU24-16054 | ECS | Posters on site | ST1.5

High energy proton and Helium spectra from SOHOs Electron Proton Helium Instrument 

Malte Hörlöck, Stefan Jensen, Bernd Heber, Patrick Kühl, and Holger Sierks

High energy protons and Helium in the heliosphere originate from multiple sources. Solar Energetic Particle events (SEPs), Anomalous Cosmic Rays (ACRs) and Galactic Cosmic Rays (GCRs) are prominent examples. Their energy spectra provide insights into acceleration and transportation processes.

The SOlar and Heliospheric Observatory (SOHO) was launched December 1995 with the Electron Proton Helium INstrument (EPHIN) measuring protons and Helium from 4 MeV/nuc to 52 MeV/nuc with an additional open ended integral channel. However, its measuring capability was reduced due to the loss of two detectors in 1997 and 2017, respectively.

Using Pulse Height Analysis (PHA) data in the integral channel, we present methods to derive energy spectra for protons up to more than 100 MeV and Helium spectra up to some 250 MeV/nuc. First results and comparisons to other instruments will be presented.

The SOHO/EPHIN project is supported under Grant 50 OC 2102 by the German Bundesministerium für Wirtschaft through the Deutsches Zentrum für Luft- und Raumfahrt (DLR). This study has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 101004159 (SERPENTINE).

How to cite: Hörlöck, M., Jensen, S., Heber, B., Kühl, P., and Sierks, H.: High energy proton and Helium spectra from SOHOs Electron Proton Helium Instrument, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16054, https://doi.org/10.5194/egusphere-egu24-16054, 2024.

EGU24-16660 | Posters on site | ST1.5 | Highlight

 In situ Observations of Ultra-Relativistic ElectronAcceleration in the Fastest Heliospheric Shock Wave by Parker Solar Probe 

Vladimir Krasnoselskikh, Immanuel Christopher Jebaraj, Oleksiy Agapitov, Laura Vuorinen, Kyung-Eun Choi, Michael Gedalin, Nicolas Wijsen, Alexandr Afanasiev, Athanasios Kouloumvakos, John Grant Mitchell, Rami Vainio, Matthew Hill, and Nour Raouafi

Collisionless shock waves (CSWs) in plasma, prevalent in diverse astrophysical contexts, are key to understanding cosmic particle acceleration. These shock waves, observable in environments from heliospheric planetary bow shocks to supernova remnants (SNRs), efficiently convert kinetic energy to thermal energy and accelerate particles to sub-relativistic and relativistic energies. A particular focus is on electrons accelerated by these shocks, as they generate electromagnetic radiation, making astrophysical shocks like SNRs observable. Despite their significance, gaps remain in our understanding of the dynamic mechanisms behind these universal accelerators, underscoring the necessity for in-depth, direct in situ measurements. Heliospheric shocks offer a unique opportunity for such in situ studies, particularly those that are strong and fast, potentially mirroring SNR shocks. This study highlights the groundbreaking in situ observations of the fastest heliospheric shock wave yet, traveling at nearly 1% the speed of light, captured by the pioneering Parker Solar Probe. Positioned just 0.23 astronomical units from the Sun, the probe directly measured the acceleration of electrons and ions to high energies amidst intense electromagnetic activity. A landmark discovery was the acceleration of electrons to ultra-relativistic speeds, with energies reaching up to 6 Million electron volts (MeV). This observation not only provides unprecedented insights into the mechanisms of particle acceleration in CSWs but also bridges the gap in our understanding of similar processes in more distant astrophysical phenomena like SNRs. The findings from the Parker Solar Probe open new avenues for exploring and comprehending the intricate processes of cosmic particle acceleration.

 

How to cite: Krasnoselskikh, V., Jebaraj, I. C., Agapitov, O., Vuorinen, L., Choi, K.-E., Gedalin, M., Wijsen, N., Afanasiev, A., Kouloumvakos, A., Mitchell, J. G., Vainio, R., Hill, M., and Raouafi, N.:  In situ Observations of Ultra-Relativistic ElectronAcceleration in the Fastest Heliospheric Shock Wave by Parker Solar Probe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16660, https://doi.org/10.5194/egusphere-egu24-16660, 2024.

EGU24-16787 | ECS | Posters on site | ST1.5

Energy spectra of Solar Energetic Electron Events Observed with Solar Orbiter 

Annamaria Fedeli, Nina Dresing, Jan Gieseler, Rami Vainio, Raúl Gómez-Herrero, Francisco Espinosa, Alexander Warmuth, and Frederic Schuller

The identification of the phenomena responsible for the acceleration of solar energetic particles (SEP) still challenges current research and limits our forecasting abilities of SEP events. Even the most recent space missions, such as Solar Orbiter and Parker Solar Probe, are still not reaching close enough distances to the Sun to be able to make direct measurements of the acceleration processes without the effects of transport mechanisms.

The analysis of SEP spectra is crucial to infer the underlying acceleration mechanisms of SEPs as different mechanisms are characterised by different spectral shapes and features. Making this connection can, however, be challenging as transport effects are also known for altering spectral shapes, and these processes are not fully understood either.

Our analysis focuses on solar energetic electrons (SEEs). The acceleration of SEEs, especially by shocks, still raises multiple questions in our field. In our analysis we use the novel measurements of the Energetic Particle Detector (EPD) on board
the Solar Orbiter spacecraft. EPD detects energetic particles with unprecedented time and energy-resolution (1-second resolution covering energies from the suprathermal to relativistic range). This data product, together with Solar Orbiter’s varying distances to the Sun, allows us to characterise features of the energy spectra of SEEs better than ever before and to pin down transport effects.

We determine the peak intensity spectra of more than 200 SEE events using newly developed techniques, taking into account velocity dispersion as well as the pitch angle coverage of the instruments. We determine and characterise the spectral features of each event by fitting the spectra with multiple mathematical models.

We will present the results of our statistical analysis and discuss which spectral features can be associated with acceleration or transport effects.

How to cite: Fedeli, A., Dresing, N., Gieseler, J., Vainio, R., Gómez-Herrero, R., Espinosa, F., Warmuth, A., and Schuller, F.: Energy spectra of Solar Energetic Electron Events Observed with Solar Orbiter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16787, https://doi.org/10.5194/egusphere-egu24-16787, 2024.

EGU24-16994 | Posters on site | ST1.5

An effective and predictive model for the long-term variations of Cosmic Rays in the Heliosphere" 

David Pelosi, Bruna Bertucci, Nicola Tomassetti, Miguel Reis Orcinha, Emanuele Fiandrini, and Fernando Barao

Investigating the connection between solar variability and energetic radiation in the heliosphere is of fundamental importance for assessing radiation exposure and associated risks in space missions.

Our research focuses on the solar modulation phenomenon of cosmic rays, that is, on the long-term variation of the cosmic-ray flux and its association with the solar activity cycle.

Here we present our endeavors to establish an effective and predictive model of solar modulation. 
Our model incorporates fundamental physics processes of particle transport such as diffusion, drift, convection and adiabatic cooling, to compute the energy spectrum and temporal evolution of the cosmic radiation in the inner heliosphere.

Calibration and validation of our model are performed using the most recent cosmic-ray data from space-based detectors, such as AMS-02 on the International Space Station, along with multichannel observations of solar activity and interplanetary parameters.

This comprehensive model not only demonstrates good results in reproducing observations but also showcases its potential in space radiation monitoring and forecasting, offering valuable insights for evaluating exposure in future space missions.

How to cite: Pelosi, D., Bertucci, B., Tomassetti, N., Reis Orcinha, M., Fiandrini, E., and Barao, F.: An effective and predictive model for the long-term variations of Cosmic Rays in the Heliosphere", EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16994, https://doi.org/10.5194/egusphere-egu24-16994, 2024.

EGU24-17271 | ECS | Orals | ST1.5

Advancing Solar Energetic Particle Event Forecasting: Integrating Remote Sensing Techniques into the Relativistic Electron Alert System for Exploration 

Janna Martens, Henrik Dröge, Bernd Heber, Karl-Ludwig Klein, Jens Berdermann, Daniela Banys, Jan Maik Wissing, Volker Wilken, and Lukas Höfig

The Relativistic Electron Alert System for Exploration (REleASE) forecasting metric, developed by Posner (2007), utilizes electron data collected by the Electron Proton Helium Instrument (EPHIN) aboard the SOHO spacecraft. Our project aims to enhance the probability of detection, decrease the false alarm rate and extend the warning time by implementing various remote sensing techniques. These include automatic flare detection and localization, as well as automatic radio burst detection using the ROBUST algorithm developed at the University of Graz.
Historically, a range of diagnostics for Solar Energetic Particle (SEP) events based on radio observations from Earth has been developed since the 1960s, which are to some extent utilized in contemporary prediction models. These diagnostics span from the occurrence of long-lasting broadband radio emissions (cm-m waves) to the spectra of microwave bursts (mm-cm waves). The presence of radio emission at meter wavelengths (e.g., type III bursts) is crucial, since it indicates particle injection into the high corona, but is absent in confined flares, where no particles escape from the active region and no CME is available to accelerate particles higher up.
Moreover, our project explores the extent to which diagnostics across diverse frequency ranges can enhance the REleASE system. Initial results of this integration and its impact on the accuracy of SEP event forecasting will be presented.

How to cite: Martens, J., Dröge, H., Heber, B., Klein, K.-L., Berdermann, J., Banys, D., Wissing, J. M., Wilken, V., and Höfig, L.: Advancing Solar Energetic Particle Event Forecasting: Integrating Remote Sensing Techniques into the Relativistic Electron Alert System for Exploration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17271, https://doi.org/10.5194/egusphere-egu24-17271, 2024.

EGU24-17642 | Posters on site | ST1.5

Very High Energy Solar Energetic Particle Events and Ground Level Enhancement Events: Forecasting and Alerts 

Norma Crosby, Helen Mavromichalaki, Olga Malandraki, Maria Gerontidou, Michalis Karavolos, Dimitra Lingri, Panagiota Makrantoni, Maria Papailiou, Pavlos Paschalis, and Anastasia Tezari

A Ground Level Enhancement (GLE) event can be observed as an increase in the background of ground-based neutron monitor observations and is often associated with an increase of >500 MeV space-based proton flux measurements. GLE events begin as very high-energy SEP events associated with GeV protons. For such events to be detected at sea level, proton energies must exceed about 433 MeV. To mitigate for potential impacts on space systems, avionics and human health, space-based and ground-based monitoring of these particles is essential, and so is having reliable real-time warning systems. Here we present two products, respectively, “GLE alert++” and “HESPERIA UMASEP-500”, that have been fully integrated as federated products on the ESA SWE Portal for this purpose. GLE alert++, built by the Athens Cosmic Ray Group of the National and Kapodistrian University of Athens, issues alerts when a GLE event has been registered and is based on ground-based neutron monitor observations. From the space-based approach, the EU HORIZON2020 HESPERIA UMASEP-500 product provides forecasts of GLE events and >500 MeV protons relying on GOES satellite soft X-ray and high-energy proton observations. Examples of how these two products complement each other will be given, as well as how using them together can in some instances provide more information for users of these services. (Work performed in the frame of ESA Space Safety Programme’s network of space weather service development and pre-operational activities, and supported under ESA Contract 4000134036/21/D/MRP.)

How to cite: Crosby, N., Mavromichalaki, H., Malandraki, O., Gerontidou, M., Karavolos, M., Lingri, D., Makrantoni, P., Papailiou, M., Paschalis, P., and Tezari, A.: Very High Energy Solar Energetic Particle Events and Ground Level Enhancement Events: Forecasting and Alerts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17642, https://doi.org/10.5194/egusphere-egu24-17642, 2024.

EGU24-18790 | ECS | Posters on site | ST1.5

Charge sign dependence of recurrent Forbush Decreases in 2016 

Lisa Romaneehsen, Johannes Marquardt, and Bernd Heber
This study investigates the periodicities of cosmic rays attributed to co-rotating interaction regions (CIRs) using AMS-02 data from late 2016 to early
2017. These data enable the first-time examination of Forbush decrease amplitudes induced by CIRs, considering rigidity and charge sign dependence. The findings from the Lomb-Scargle algorithm and Superposed Epoch Analysis were compared. Results reveal that the rigidity dependence of proton decreases in the northern coronal hole aligns with existing literature, while the southern coronal hole shows no rigidity dependence. Helium modulation surpasses that of protons, in line with previous observations, while limited statistical data for positrons prevent definitive conclusions. Notably, the modulation behavior of electrons differs from that of positively charged particles.
 
 

How to cite: Romaneehsen, L., Marquardt, J., and Heber, B.: Charge sign dependence of recurrent Forbush Decreases in 2016, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18790, https://doi.org/10.5194/egusphere-egu24-18790, 2024.

EGU24-20152 | ECS | Orals | ST1.5

Observations of a Solar Energetic Particle Eventon March 28th 2022 by the BepiColombo Satellite 

Mirko Stumpo, Monica Laurenza, Simone Benella, Anna Milillo, Christina Plainaki, Stefano Orsini, Ali Varsani, Gunter Laky, Stas Barabash, Hayley Williamson, Hans Nillson, Beatriz Sanchez-Cano, Go Murakami, Yoshifumi Saito, Lina Hadid, Daniel Hayner, Alessandro Aronica, Pier Paolo Di Bartolomeo, Adrian Kazakov, and Martina Moroni and the other authors

On March 28, 2022, a particle flux increase was recorded at very different energies by the several particle instruments on board the BepiColombo (BC) spacecraft. Specifically, an increase in the low-energy ion flux was measured by the SERENA/PICAM instrument and one in both the proton (1.5 – 20.7 MeV) and electron (>0.5 MeV) flux was detected by the BERM radiation monitor. These observations are consistent with the occurrence of a Solar Energetic Particle (SEP) event. This study presents a comprehensive analysis of the observed SEP event, exploiting BC's unique vantage point to explore temporal, spatial, and energetic characteristics, as well as observations from other spacecraft in the inner heliosphere. In conjunction with BC's observations, we used data from the STEREO-A, which is very well magnetically connected with BC along the spiral magnetic field, and data provided by spacecraft positioned at the Lagrangian point L1, such as ACE and WIND, which are radially connected with BC. The findings provide insights into the physical mechanisms governing SEP events, offering a perspective on their solar origin, propagation, and evolution within the heliosphere.

How to cite: Stumpo, M., Laurenza, M., Benella, S., Milillo, A., Plainaki, C., Orsini, S., Varsani, A., Laky, G., Barabash, S., Williamson, H., Nillson, H., Sanchez-Cano, B., Murakami, G., Saito, Y., Hadid, L., Hayner, D., Aronica, A., Di Bartolomeo, P. P., Kazakov, A., and Moroni, M. and the other authors: Observations of a Solar Energetic Particle Eventon March 28th 2022 by the BepiColombo Satellite, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20152, https://doi.org/10.5194/egusphere-egu24-20152, 2024.

EGU24-20809 | Orals | ST1.5

Observations of Suprathermal Ions(5-75 keV) in Association with Shocks 

Stefano Livi, Christopher Owen, Philippe Louarn, Roberto Bruno, Andrei Fedorov, Raffaella D'Amicis, George Ho, Benjamin Alterman, Susan Lepri, Jim Raines, Ryan Dewey, Antoinette Galvin, Lynn Kistler, Frederic Allegrini, Keiichi Ogasawara, and Peter Wurz

The Heavy Ion Instrument (HIS) onboard Solar Orbiter measures mass, charge, and full 3-D velocities of ions in the energy/charge range 0.5-75keV/charge. Using the data from HIS we study how interplanetary events like shocks or CME fronts create suprathermal tails in the velocity distribution and how those tails change with time. HIS observed the passage of three interplanetary shocks during the period October 2021 - May 2022. The three events were characterized by the acceleration of plasma from the solar wind energy regime (~1keV per amu/charge) to higher energies (5-75 keV), commonly referred to as suprathermal ions; later during the events, energetic particles (100keV and above) were measured by the EPD instrument. This energization process was characterized by a clear dependence upon mass/charge, and found consistent with preferential acceleration of ions present in the high energy tails of solar wind distributions, the seed population. Details of the distribution functions during the three events are presented and contrasted to each other.

How to cite: Livi, S., Owen, C., Louarn, P., Bruno, R., Fedorov, A., D'Amicis, R., Ho, G., Alterman, B., Lepri, S., Raines, J., Dewey, R., Galvin, A., Kistler, L., Allegrini, F., Ogasawara, K., and Wurz, P.: Observations of Suprathermal Ions(5-75 keV) in Association with Shocks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20809, https://doi.org/10.5194/egusphere-egu24-20809, 2024.

NASA's Artemis missions are taking astronauts back to the Moon with a view towards Mars. The dynamic space climate and space weather environment is a concern for space radiation operations and the protection of astronauts. The NASA Space Radiation Analysis Group (SRAG) at Johnson Space Center is developing the requirements and tools needed for quick operational response to space weather events during mission operations. To estimate long-timescale changes in the galactic cosmic ray (GCR) background due to solar modulation, SRAG maintains and develops NASA's Badhwar-O'Neill galactic cosmic ray (GCR) model. On short timescales, SRAG provides measurements, tools, expertise, and console support to keep crew safe during explosive solar energetic particle (SEP) events. In the past few years, SRAG, in collaboration with NASA Community Coordinated Modeling Center (CCMC) and the Moon to Mars Space Weather Analysis Office (M2M), has been working directly with the research community to onboard SEP models into real time operations. Real time forecasts are visualized in the SEP Scoreboards developed by CCMC and currently under evaluation by SRAG for radiation operations. An intensive validation effort has been ongoing to develop the infrastructure and standards for the validation of SEP model performance. This effort has broadly engaged the US, European, and worldwide scientific community through community challenges as well as focused on the evaluation of model performance in a real time operational environment. These efforts and preliminary outcomes will be described.

How to cite: Whitman, K.: Addressing the Dynamic Energetic Particle Environment for Space Radiation Operations at NASA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21303, https://doi.org/10.5194/egusphere-egu24-21303, 2024.

EGU24-21919 | Posters on site | ST1.5

Energetic particles observed by Solar Orbiter associated with a sharp shock wave passage from the solar backside event of March 13-14, 2023 

Oleksiy Dudnik, Oleksandr Yakovlev, Glenn Mason, George Ho, Athanasios Kouloumvakos, Robert Wimmer-Schweingruber, Javier Rodriguez-Pacheco, Francisco Espinosa Lara, Raul Gómez Herrero, Bogdan Dudnik, and Anna Képa

Acceleration of charged particles in solar flares, during reconnection of magnetic field lines in coronal loops, and by shock waves in the solar corona and interplanetary space are some of the substantial physical processes being studied by the Solar Orbiter mission. Cross-analysis of the light curves of the non-thermal parts of X-ray flares energy spectra registered by the Spectrometer Telescope for Imaging X-rays (STIX), and high-energy charged particle spectrograms recorded by the Energetic Particle Detector (EPD) suite assist us in furthering our understanding of these events.

The anomalies and events in interplanetary space such as shocks, CIRs, ICMEs, solar and interplanetary radio bursts, SEPs being investigated in situ regime are typically associated with solar X-ray flares and/or SDO/AIA measurements of the solar atmosphere in multiple wavelengths when sources are on the visible side of the solar disk. In cases where the powerful flare occurs on the Sun's backside, the massive CME can reach the volumes in the interplanetary space right at the opposite side of the CME’s seed and manifests in different forms of irregularities in the solar wind parameters and magnetic field components as well in enhanced energetic particle fluxes. Such types of occasions are of particular interest due to their near-global impact on the inner heliosphere.

In this study, we conduct a cross-analysis of the data derived from the Solar Wind Analyzer Proton-Alpha Sensor (SWA-PAS), Magnetometer (MAG), and EPD suite onboard the Solar Orbiter for the period of 13-14 March 2023, when a high-speed CME launched from near 180° from Earth accelerated an enormous quantity of high energy charged particles, from electrons to iron ions. At the time SolO was located 26°East of the Earth-Sun line at a distance of about 0.6 au. Even so, the CME quickly reached the spacecraft and manifested as a very sharp and strong shock at the front of which particles were accelerated additionally. In the analysis, we involve the data from the Suprathermal Ion Spectrograph (SIS), the SupraThermal Electrons and Protons (STEP), and the Electron Proton Telescope (EPT) of the EPD suite.

This work is supported by the “Long-term program of support of the Ukrainian research teams at the Polish Academy of Sciences carried out in collaboration with the U.S. National Academy of Sciences with the financial support of external partners”.

How to cite: Dudnik, O., Yakovlev, O., Mason, G., Ho, G., Kouloumvakos, A., Wimmer-Schweingruber, R., Rodriguez-Pacheco, J., Espinosa Lara, F., Gómez Herrero, R., Dudnik, B., and Képa, A.: Energetic particles observed by Solar Orbiter associated with a sharp shock wave passage from the solar backside event of March 13-14, 2023, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21919, https://doi.org/10.5194/egusphere-egu24-21919, 2024.

EGU24-1196 | ECS | Posters on site | ST1.7

Quantifying how surface complexity influences properties of the solar corona and solar wind 

Caroline Evans, Cooper Downs, Don Schmit, and James Crowley

Astrophysical simulations require trade-offs between compute time and physical accuracy. This frequently includes targeting certain physical scales at the expense of others. Simulations investigating solar coronal heating and solar wind acceleration usually select either high resolution for a small domain or low resolution for a global domain. Bridging this gap requires linking structures present on the solar surface to both the middle corona (approximately 1.5 - 6 solar radii) and the solar wind. In this work we analyze three simulations of the global solar corona that vary the resolution of the surface boundary condition while keeping the same parameterization of a thermodynamic, wave-turbulence-driven magnetohydrodynamic model. We quantify structural differences endemic to each simulation using spherical harmonic decomposition and associated statistics. We use this information to examine how surface resolution influences heating and magnetic complexity in the corona and solar wind and the subsequent impacts on density, temperature, and flow structure. In principle, this can enable more efficient subgrid modeling in future low resolution simulations.

How to cite: Evans, C., Downs, C., Schmit, D., and Crowley, J.: Quantifying how surface complexity influences properties of the solar corona and solar wind, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1196, https://doi.org/10.5194/egusphere-egu24-1196, 2024.

EGU24-1947 | ECS | Posters on site | ST1.7

Fine Structures of Radio Bursts from Flare Star AD Leo with FAST Observations 

Jiale Zhang and Hui Tian

Radio bursts from nearby active M-dwarfs have been frequently reported and extensively studied in solar or planetary paradigms. Whereas, their substructures or fine structures remain rarely explored despite their potential significance in diagnosing the plasma and magnetic field properties of the star. Such studies in the past have been limited by the sensitivity of radio telescopes. Here we report the inspiring results from the high time-resolution observations of a known flare star AD Leo with the Five-hundred-meter Aperture Spherical radio Telescope. We detected many radio bursts in the 2 days of observations with fine structures in the form of numerous millisecondscale sub-bursts. Sub-bursts on the first day display stripe-like shapes with nearly uniform frequency drift rates, which are possibly stellar analogs to Jovian S-bursts. Sub-bursts on the second day, however, reveal a different blob-like shape with random occurrence patterns and are akin to solar radio spikes. The new observational results suggest that the intense emission from AD Leo is driven by electron cyclotron maser instability, which may be related to stellar flares or interactions with a planetary companion.

How to cite: Zhang, J. and Tian, H.: Fine Structures of Radio Bursts from Flare Star AD Leo with FAST Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1947, https://doi.org/10.5194/egusphere-egu24-1947, 2024.

EGU24-3450 | ECS | Posters on site | ST1.7

The Effect of the Parametric Decay Instability on the Morphology of Coronal Type III Radio Bursts 

Chaitanya Sishtla, Immanuel Jebaraj, Jens Pomoell, Norbert Magyar, Marc Pulupa, Emilia Kilpua, and Stuart Bale

The nonlinear evolution of Alfvén waves in the solar corona leads to the generation of Alfvénic turbulence. This description of the Alfvén waves involves parametric instabilities where the parent wave decays into slow mode waves giving rise to density fluctuations. These density fluctuations, in turn, play a crucial role in the modulation of the dynamic spectrum of type III radio bursts, which are observed at the fundamental of local plasma frequency and are sensitive to the local density. During observations of such radio bursts, fine structures are detected across different temporal ranges. In this study, we examine density fluctuations generated through the parametric decay instability (PDI) of Alfvén waves as a mechanism to generate striations in the dynamic spectrum of type III radio bursts using magnetohydrodynamic simulations of the solar corona. An Alfvén wave is injected into the quiet solar wind by perturbing the transverse magnetic field and velocity components, which subsequently undergo the PDI instability. The type III burst is modeled as a fast-moving radiation source that samples the background solar wind as it propagates to emit radio waves. We find the simulated dynamic spectrum to contain striations directly affected by the multiscale density fluctuations in the wind.

How to cite: Sishtla, C., Jebaraj, I., Pomoell, J., Magyar, N., Pulupa, M., Kilpua, E., and Bale, S.: The Effect of the Parametric Decay Instability on the Morphology of Coronal Type III Radio Bursts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3450, https://doi.org/10.5194/egusphere-egu24-3450, 2024.

EGU24-3926 | Posters virtual | ST1.7

Detection of a corotating interaction region in solar wind using RPW and SWA instruments of the Solar Orbiter mission. 

Dmytro Chechotkin, Oleksandr Yakovlev, and Oleksandr Bilokon

The study of characteristics, size, and shape variations of corotating interaction region (CIR) with changes in heliocentric distance is of scientific interest. The unique orbit parameters of the Solar Orbiter spacecraft (SOLO) and its set of equipment provide an opportunity to address the posed question. In our study, an attempt has been made to identify CIR regions using only data from the SOLO instruments.

The methodology for identifying CIR is well-developed. It involves in-situ observations of solar wind parameters, such as those proposed in the works of Hajra and Sunny, and verifies the potential presence of high-speed streams (HSS) from coronal holes. Such verification can be performed using SDO/AIA extreme ultraviolet observation data. This methodology can be easily implemented considering the near-Earth satellite constellation. Often, the trajectory of the SOLO passes out of the visibility range of near-Earth solar observation facilities, and there is no opportunity to verify the presence of coronal holes on the solar disk, which could be sources of HSS. In such cases, it is necessary to rely solely on the data from the SOLO instruments.

During the analysis of RPW instrument data, it was observed that sometimes the instrument registers shock events not confirmed by SWA instrument data. However, these events demonstrate an intense increase in solar wind speed and other parameters. The hypothesis has been put forward that multiple activations of the RPW instrument's SBM1 algorithm within a day can be used as a marker for the spacecraft's presence in the CIR zone. To validate this hypothesis, a comparative analysis of RPW data at the time of SBM1 events is conducted, comparing it with data from the SWA-PAS instrument. Based on the examples considered, a conclusion is drawn regarding the ability to track the spacecraft's entry and exit moments from the CIR region and assess the changes in CIR parameters when the spacecraft is within it.

This work is supported by the “Long-term program of support of the Ukrainian research teams at the Polish Academy of Sciences carried out in collaboration with the U.S. National Academy of Sciences with the financial support of external partners”.

How to cite: Chechotkin, D., Yakovlev, O., and Bilokon, O.: Detection of a corotating interaction region in solar wind using RPW and SWA instruments of the Solar Orbiter mission., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3926, https://doi.org/10.5194/egusphere-egu24-3926, 2024.

EGU24-3962 | Posters on site | ST1.7

Simulating Differences in Helium Abundances between Fast and Slow Solar Winds 

Simon Thomas, Alexis Rouillard, Paul Lomazzi, Nicolas Poirier, and Pierre-Louis Blelly

To forecast the solar wind arriving at Earth in advance, and hence its impacts on technology, it is important to have a good understanding of how the solar wind is generated by the solar corona. Helium is a major constituent of the corona/solar wind that plays an important role in the energy budget of the corona and the acceleration of the solar wind. Helium abundance varies significantly with the solar cycle and in the different types of fast and slow solar winds. We present the newly-developed multi-species IRAP Solar Atmospheric Model (ISAM) which solves for the coupled transport of both neutral and charged particles between the chromosphere and the corona, including a self-consistent treatment of collisional and ionisation processes. We exploit ISAM to study the mechanisms that regulate Helium abundance in the source region of the fast and slow solar winds and contrast numerical results with and without Helium included in the model. We compare our model outputs with as many observations as possible, including Helios, Parker Solar Probe and Solar Orbiter data, in particular from the Proton and Alpha particle Sensor, SWA-PAS. We show that our simulations are in good agreement with previous studies, in particular that the solar cycle variation in Helium abundance can be explained by differences in abundance found for each solar wind type by ISAM, when just using diffusion in the model and not (yet) including the ponderomotive force. 

How to cite: Thomas, S., Rouillard, A., Lomazzi, P., Poirier, N., and Blelly, P.-L.: Simulating Differences in Helium Abundances between Fast and Slow Solar Winds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3962, https://doi.org/10.5194/egusphere-egu24-3962, 2024.

EGU24-4218 | Orals | ST1.7

Detection of long-lasting aurora-like radio emission above a sunspot 

Sijie Yu, Bin Chen, Rohit Sharma, Timothy Bastian, Surajit Mondal, Dale Gary, Yingjie Luo, and Marina Battaglia

We present our findings on long-lasting radio emissions above a sunspot, analogous to planetary auroral radio emissions. These emissions are typically characterized by highly polarized, intense radio bursts, generally attributed to electron cyclotron maser (ECM) emission from energetic electrons in regions with converging magnetic fields, such as planetary polar areas. Similar bursts have been observed in magnetically active low-mass stars and brown dwarfs, often prompting analogous interpretations. Here we report observations of long-lasting solar radio bursts with high brightness temperature, wide bandwidth, and high circular polarization fraction akin to these auroral and exo-auroral radio emissions, albeit two to three orders of magnitude weaker than those on certain low-mass stars. Our spatial, spectral, and temporal analysis indicate that the source is situated above a sunspot where a strong, converging magnetic field is present. The morphology and frequency dispersion of the source align with ECM emissions, likely driven by energetic electrons from recurring nearby solar flares. These observations provide new insights into the nature of intense solar radio bursts and suggest a potential model for understanding aurora-like radio emissions in other flare stars with significant starspots.

How to cite: Yu, S., Chen, B., Sharma, R., Bastian, T., Mondal, S., Gary, D., Luo, Y., and Battaglia, M.: Detection of long-lasting aurora-like radio emission above a sunspot, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4218, https://doi.org/10.5194/egusphere-egu24-4218, 2024.

EGU24-4309 | ECS | Posters on site | ST1.7

How the structure of rarefaction regions develops? 

Tereza Ďurovcová, Jana Šafránková, and Zdeněk Němeček

As the solar wind streams propagate with different speeds through the interplanetary space, they meet and interact. This leads to the formation of large interaction regions, one of which is the rarefaction regions (RRs). RRs develop at the trailing edge of the fast solar wind stream and come from an area of small longitudinal extent on the Sun. They exhibit a fine and complex structure, and the stream interface position is usually unclear. Superposed epoch analysis of the proton and alpha parameters for different regions within RRs reveals gradual transitions in many of them. Moreover, majority of our observations show that most of the RR plasma parameters correspond to the fast solar wind characteristics, only the alpha-proton drift velocity decreases from the beginning of RR. We investigate different ways of its reduction in the interplanetary space and show that this feature is likely associated with the mirroring of the multi-component solar wind. We identify the composition boundary where the alpha relative abundance and alpha-proton temperature ratio change abruptly from the values typical for the fast wind toward slow wind values. We suggest that this boundary is the most probable candidate for the stream interface. Based on these findings, we speculate that the RR formation occurs near the Sun and formulate two possible scenarios.

How to cite: Ďurovcová, T., Šafránková, J., and Němeček, Z.: How the structure of rarefaction regions develops?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4309, https://doi.org/10.5194/egusphere-egu24-4309, 2024.

EGU24-4450 | Posters virtual | ST1.7 | Highlight

Measuring Magnetic Fields of Coronal Mass Ejection in Corona and Inner Heliosphere using Wide Field of View Spectro-polarimetric Radio Imaging 

Devojyoti Kansabanik, Divya Oberoi, Angelos Vourlidas, and Surajit Mondal

Coronal mass ejections (CMEs) are the strongest drivers of space weather. Measurements of the plasma parameters of CMEs, particularly magnetic fields entrained in the CME plasma, are crucial to understand their propagation, evolution, and geo-effectiveness. Spectral modeling of gyrosynchrotron (GS) emission from CME plasma has long been regarded as one of the most promising remote observation techniques for estimating spatially resolved CME plasma parameters. However, imaging the very low flux density CME GS emission in close proximity to the Sun with orders of magnitude higher flux density, has proven to be rather challenging. This challenge has only recently been met using the combination of data from the Murchison Widefield Array (MWA) and the recently developed spectropolarimetric snapshot imaging pipeline optimized for this data (P-AIRCARS). This has now brought routine detection of GS within reach, and the next challenge to be overcome is that of constraining the large number of free parameters in GS models. A few of these parameters are degenerate, and need to be constrained using the limited number of spectral measurements typically available. We present studies of spectropolarimetric modeling GS emissions from two different CMEs, which establish that these degeneracies can be broken using polarimetric imaging. 


However, this methodology is only useful to measure CME magnetic fields up to ~10 R๏. At  higher coronal heights and inner heliosphere CME magnetic fields can be estimated by measuring Faraday rotation of linearly polarized galactic/extragalactic radio sources. This method has been used using small field of view (FoV) instruments at high frequency (e.g., VLA) to measure magnetic fields along a single line of sight (LoS). We have recently started exploring the FR measurements due to CME using the MWA. The  advantage of using the MWA is its wide FoV and lower observing frequency. Lower observing frequency provides sensitivity to smaller magnetic fields. At the same time, wide FoV will provide simultaneous measurements along multiple LoSs and enable estimation of vector magnetic fields by constraining empirical flux-rope models of CMEs.  We present the challenges which need to be overcome to achieve these goals and some initial results.  

How to cite: Kansabanik, D., Oberoi, D., Vourlidas, A., and Mondal, S.: Measuring Magnetic Fields of Coronal Mass Ejection in Corona and Inner Heliosphere using Wide Field of View Spectro-polarimetric Radio Imaging, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4450, https://doi.org/10.5194/egusphere-egu24-4450, 2024.

EGU24-6603 | ECS | Posters on site | ST1.7

Global Modeling of Heavy Ions in the Solar Corona and Inner Heliosphere with Multi-Ion-AWSoM 

Judit Szente, Enrico Landi, and Bart van der Holst

The goal of this study is to narrow down the uncertainties global modeling and PFSS back-tracing introduces when source regions are identified for in-situ data collections. We use the Space Weather Modeling Framework's Multi-Ion Alfven Wave Solar atmosphere Model with non-equilibrium ionization of heavy ions (NEI) to connect the remote sensing and in-situ signatures of solar wind properties from formation into the heliosphere. We use the NEI resulting charge state distributions and in-situ plasma properties to identify and connect source regions and their relating spectral emission signatures. The advantage of 3D modeling is that it enables data decomposition along the line-of-sight and study the effect of individual processes that result in the synthetic and actual observables. 

How to cite: Szente, J., Landi, E., and van der Holst, B.: Global Modeling of Heavy Ions in the Solar Corona and Inner Heliosphere with Multi-Ion-AWSoM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6603, https://doi.org/10.5194/egusphere-egu24-6603, 2024.

EGU24-6743 | Posters on site | ST1.7

The solar wind in the last solar cycle driven by ADAPT-GONG and GONG magnetograms 

Zhenguang Huang, Gabor Toth, Nishtha Sachdeva, and Bartholomeus van der Holst

The solar wind variations during a solar cycle are critical in understanding the solar wind acceleration mechanism in different phases of the solar cycle. It is also important in predicting the solar wind distribution in the heliosphere. This problem has been investigated from different aspects, from data analysis to numerical modeling. Previous observations have shown that the distribution of fast and slow wind are different between solar minimum and maximum. In this study, we study the solar wind variations based on a first-principles model, the Alfven Wave Solar atmosphere Model (AWSoM) developed at the University of Michigan. Huang et al. (2023) have used the ADAPT-GONG magnetograms in the last solar cycle to drive the solar wind model and shown that one of the input parameters of the model, the Poynting flux parameter, can be empirically predicted with the open field area. Moreover, they suggested that the average energy deposition rate in the open field regions is approximately constant during a solar cycle. In this study, we use the GONG synoptic magnetograms, and determine if similar conclusions are also valid. We also systematically compare the model performance between the two different input magnetograms.

How to cite: Huang, Z., Toth, G., Sachdeva, N., and van der Holst, B.: The solar wind in the last solar cycle driven by ADAPT-GONG and GONG magnetograms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6743, https://doi.org/10.5194/egusphere-egu24-6743, 2024.

EGU24-8939 | ECS | Orals | ST1.7 | Highlight

Single-dish solar imaging at high radio frequencies: SunDish & Solaris Projects 

Sara Mulas and the SunDish and Solaris

The SunDish and Solaris projects are devoted to solar radio imaging and monitoring up to 100 GHz using existing INAF large radio telescopes in Italy, and smaller and flexible radio telescopes in development for polar regions. This powerful network can complement other existing ground-based and space-based facilities aimed at the direct monitoring of the solar atmosphere both for Heliophysics science and Space Weather awareness.

The SunDish Project aims to map the brightness temperature of the solar atmosphere in the radio band to reveals plasma processes mostly originating from free-free emission in the local thermodynamic equilibrium, providing a probe of physical conditions in a wide range of atmospheric layers. In particular, long-term diachronic observations of the solar disk at high radio frequencies represents an effective tool to characterise the vertical structure and physical conditions of the solar chromosphere both for quiet and active regions during their evolution at different phases of the solar cycle. Within this context, the Medicina 32-m and SRT 64-m radiotescopes could have an important role in the international solar radio science panorama.
After a first test campaign aimed at defining and optimising solar imaging requirements for the radio telescopes, the system is ready for systematic monitoring of the Sun to provide: (1) accurate measurement of the brightness temperature of the radio quiet Sun component, that has been poorly explored in the 20-26 GHz range to date, and representing a significant constraint for atmospheric models; (2) characterisation of the flux density, spectral properties and long-term evolution of dynamical features (active regions, coronal holes, loop systems, streamers and the coronal plateau). One of our future scientific goals is the comparison of our results with recently updated flare catalogs, based on GOES and AGILE data, in order to correlate our active regions data with the flares detections. The prediction of powerful flares through the detection of peculiar spectral variations in the active regions is a valuable forecasting probe for the Space Weather hazard network. For more information and early science results see: https://sites.google.com/inaf.it/sundish

The Solaris Project is a scientific and technological project aimed at the development of a smart Solar monitoring system at high radio frequencies based on innovative single-dish imaging techniques, recently approved as a permanent observatory in Antarctica. It combines the implementation of dedicated and interchangeable high-frequency receivers on existing small single-dish radio telescope systems (1.5/2.6-m class) available in our laboratories and in Antarctica, to be adapted for Solar observations. Operations in Antarctica will offer unique observing conditions (very low sky opacity and long Solar exposures) and unprecedented Solar monitoring in radio W-band (70-120 GHz). This opens for the identification and spectral analysis of active regions before, after and during the occurrence of Solar flares. For more information see: https://sites.google.com/inaf.it/solaris

How to cite: Mulas, S. and the SunDish and Solaris: Single-dish solar imaging at high radio frequencies: SunDish & Solaris Projects, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8939, https://doi.org/10.5194/egusphere-egu24-8939, 2024.

EGU24-9337 | Orals | ST1.7

Evolutions of Stream Interaction Region in the Inner Heliosphere and Coronal Hole Morphologies 

Daniel Milošić, Manuela Temmer, Stephan Heinemann, and Stefan Hofmeister

Stream interaction regions (SIRs) are formed when the fast solar wind streams with their origin in coronal holes (CHs) interact with the surrounding slow solar wind in the Heliosphere. Previous studies have analyzed different types of CHs and the resulting characteristics of SIRs at 1 AU (e.g., Heinemann et al., 2018, Samara et al., 2022). For the inner heliosphere, however, research on the relation between CH morphology and HSS/SIR characteristics is scarce. We extract CH morphologies from SDO/AIA and use solar wind parameters from multiple spaceraft, including Parker Solar Probe, Solar Orbiter, STEREO-A, ACE and WIND. Combining in-situ measurements and remote sensing image data, we show the evolution and statistics of solar wind profiles in HSSs/SIRs in the inner Heliosphere for multiple cases from Solar Cycle 24 and 25. 

How to cite: Milošić, D., Temmer, M., Heinemann, S., and Hofmeister, S.: Evolutions of Stream Interaction Region in the Inner Heliosphere and Coronal Hole Morphologies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9337, https://doi.org/10.5194/egusphere-egu24-9337, 2024.

EGU24-9971 | Orals | ST1.7

Toward Commissioning Solar Observations with MeerKAT: Opening a New Frontier in Solar Radio Physics 

Divya Oberoi, Devojyoti Kansabanik, Marcel Gouws, Sarah Buchner, and Surajit Mondal

Solar radio emissions provide several unique diagnostics tools of the solar corona, which are otherwise inaccessible. However, imaging the very dynamic coronal emissions spanning a large range of angular scales at radio wavelengths is extremely challenging. Due to large numbers of antennas, at GHz frequencies, MeerKAT radio telescope is possibly globally the best-suited instrument at present for providing high-fidelity spectroscopic snapshot solar images. At GHz frequencies the Sun has much higher flux density than any other astronomical sources in the sky. Hence, observing the Sun with sensitive radio telescopes like MeerKAT requires one to attenuate the solar signal suitably for optimum operation of the instrument. We embarked on our voyage of  MeerKAT solar observation using the sidelobes of the primary beam. The images show extremely good morphological similarities with the EUV images as well as the simulated radio images at MeerKAT frequencies demonstrating the high-fidelity of these images. Although this approach was successful, it is naturally better to observe the Sun in the main lobe of the primary beam using suitable attenuation in the signal chain to keep the system in the linear regime. We have been working towards this and will present the current status of our efforts toward commissionsing solar observations with the MeerKAT. Once commissioned, this will enable a host of novel studies, open the door to a large unexplored phase space with significant discovery potential, and also pave the way for solar science with the upcoming Square Kilometre Array-Mid telescope, for which MeerKAT is a precursor.

How to cite: Oberoi, D., Kansabanik, D., Gouws, M., Buchner, S., and Mondal, S.: Toward Commissioning Solar Observations with MeerKAT: Opening a New Frontier in Solar Radio Physics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9971, https://doi.org/10.5194/egusphere-egu24-9971, 2024.

EGU24-10009 | ECS | Posters on site | ST1.7 | Highlight

A Community Dataset for Comparing Automated Coronal Hole Detection Schemes and its Imprint on Magnetic Models 

Satabdwa Majumdar, Martin Reiss, Karin Muglach, Emily Mason, Emma Davies, and Shibaji Chakraborty and the S2-01 ISWAT Team

It is now known that the fast solar wind streams originating from coronal holes can have a significant contribution to geomagnetic activity, particularly during periods of low solar activity. Moreover, coronal holes, many of which are long lived and overall time steady structures, have proven to be ideal hunting grounds for understanding the fast solar wind. In this regard, automated detection schemes are nowadays a standard approach for locating coronal holes in EUV images from the Solar Dynamics Observatory (SDO). However, several inevitable factors make this automatic identification challenging. While discrepancies between detection schemes have been noted in the literature, a comprehensive assessment of these discrepancies, which is still lacking, is of equal importance. Here we present the first community dataset for comparing automated coronal hole detection schemes. This dataset consists of 29 SDO images, all of which were selected by experienced observers to challenge automated schemes. We then use this dataset as input to 14 widely-applied automated schemes to study coronal holes and collect their detection results. From this, we select and study three SDO images that exemplify the most important lessons learned from this effort. We find that different detection schemes highlight significantly different physical properties of coronal holes. Motivated by these outcomes, we look into the effect of these results on the inferred magnetic connectivity in the corona by comparing the detected coronal hole boundaries to magnetic model solutions. These results, along with the database, will provide rich inputs to our understanding of coronal holes and their connection to the solar wind.

How to cite: Majumdar, S., Reiss, M., Muglach, K., Mason, E., Davies, E., and Chakraborty, S. and the S2-01 ISWAT Team: A Community Dataset for Comparing Automated Coronal Hole Detection Schemes and its Imprint on Magnetic Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10009, https://doi.org/10.5194/egusphere-egu24-10009, 2024.

EGU24-11649 | ECS | Orals | ST1.7

Examining the Coronal Source and Inner Heliospheric Evolution of a Stream Sampled by Parker Solar Probe and Solar Orbiter 

Yeimy Rivera, Samuel Badman, Tamar Ervin, Enrico Landi, John Raymond, Katharine Reeves, Soumya Roy, Michael Stevens, and Tania Varesano

With the growing number of solar probes across the inner heliosphere, our community, now more than ever, is well placed to continuously track the formation and supersonic expansion of the solar wind from the Sun. To capture the conditions of solar wind release connected to heliospheric structures, it is fundamental to link near-synchronous measurements of its state in the corona to the associated stream’s interplanetary propagation. This goal can be achieved through well-aligned spacecraft conjunctions, measuring local plasma conditions, with integrated remote sensing observations of the stream’s coronal birthplace. As such, this work traces a solar wind stream from its source to interplanetary space through combined remote (Solar Orbiter/FSI and SPICE, SDO/AIA, Hinode/EIS) and in situ (Parker Solar Probe, Solar Orbiter) observations of the same solar wind stream at two heliospheric distances. Using remote coverage of the source region’s thermal and elemental composition properties, the solar wind is connected throughout the heliosphere by its heavy ion composition to relate energetics of the wind at different stages of its heliospheric evolution to its source region conditions. 

How to cite: Rivera, Y., Badman, S., Ervin, T., Landi, E., Raymond, J., Reeves, K., Roy, S., Stevens, M., and Varesano, T.: Examining the Coronal Source and Inner Heliospheric Evolution of a Stream Sampled by Parker Solar Probe and Solar Orbiter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11649, https://doi.org/10.5194/egusphere-egu24-11649, 2024.

EGU24-12058 | ECS | Posters on site | ST1.7

Studying the Long-Term Variability of the Solar Corona Using Modeling and Remote-Sensing Observations  

Gergely Koban, Judit Szente, and Bart van der Holst

The Sun is a subject to vivid research due to its significant impact on our daily existence. We know about the periodic behaviour in the structure of the Sun, the 11-year solar cycle, but we have yet to fully understand what it means for the inner heliosphere and how it affects the solar wind. Accurately modelling these structural changes in the solar Corona on large time scales is important to understand and even predict solar weather patterns that could potentially influence Earth's magnetic field, telecommunications, and even space missions. Fully comprehending these changes is crucial for enhancing our ability to forecast and prepare for potential solar events that might affect various aspects of our technological infrastructure and space exploration endeavours. 

To this end, we have prepared a database of solar corona and inner heliosphere simulations with the Space Weather Modeling Framework’s Alfvén Wave Solar atmosphere Model (SWMF/AWSoM) during Solar Cycles 24 and 25. Using SolarSoft’s FORWARD we study the distribution and emission of solar wind origins, such as coronal holes and active regions, throughout the solar cycles and analyse how well AWSoM is reproducing them at different phases of the solar cycle. We also compare how 1AU in-situ plasma measurements are predicted and how it relates to the reproduction of the origin of the solar wind in the corona.  

Studying the reproducibility of the coronal and heliospheric plasma throughout decades of time can prove invaluable in understanding changes in the solar structure during a solar cycle and benchmark the accuracy of the models’ predictive power in the future. 

How to cite: Koban, G., Szente, J., and van der Holst, B.: Studying the Long-Term Variability of the Solar Corona Using Modeling and Remote-Sensing Observations , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12058, https://doi.org/10.5194/egusphere-egu24-12058, 2024.

EGU24-12235 | ECS | Posters on site | ST1.7

Report on In Situ Observations of the Anti-Correlated Variations in Freeze-in Temperatures of Heavy Ions in the Solar Wind 

Chaoran Gu, Verena Heidrich-Meisner, and Robert F. Wimmer-Schweingruber

When solar wind plasma propagates outward, the electron density decreases rapidly with solar distance, and charge states of heavy ions freeze in at 1 to 5 solar radii. Thus, charge states of heavy ions carry important information about the temperature profile in the lower corona. Oxygen and Iron ions are the most abundant heavy ions in the solar wind, and their data quality is relatively higher than that of other heavy ion species.Statistically, the averaged charge states of O and Fe in the solar wind usually maintain a weak positive correlation, sometimes exhibiting a strong positive correlation in solar wind associated with Coronal Mass Ejections (CMEs). The averaged charge states of O and Fe also correlate with solar wind speed and the solar cycle.

In this study, we use ten years of in-situ solar wind Oxygen and Iron ion data obtained from the Solar Wind Ion Composition Spectrometer (SWICS) aboard the Advanced Composition Explorer (ACE). The data set is derived from Pulse Height Analysis (PHA) data, ensuring high time resolution (12 minutes).

We identify around one hundred structures (time periods) where the averaged charge states of Fe and O exhibit significant anti-correlations (Spearman rank correlation coefficient lower than -0.5). These structures have distinct signatures. We analyze the time scales of these structures, the magnitudes of the averaged charge state variations for O and Fe, the temporal lags between the onset and end of those variations , the distribution of structures in the solar wind (e.g., whether they are associated with Interplanetary Coronal Mass Ejections (ICMEs) and their relative position within ICMEs), and their distribution in the solar cycle.

Compared to more widely occurring positive correlation structures, anti-correlation structures are rarer and more interesting, reflecting the complex variations in the radial temperature profile and electron density profile of the lower corona. Large-scale anti-correlation structures suggest the presence of a relatively stable radial energy transfer process within 1 to 5 solar radii.

How to cite: Gu, C., Heidrich-Meisner, V., and Wimmer-Schweingruber, R. F.: Report on In Situ Observations of the Anti-Correlated Variations in Freeze-in Temperatures of Heavy Ions in the Solar Wind, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12235, https://doi.org/10.5194/egusphere-egu24-12235, 2024.

EGU24-12703 | Posters on site | ST1.7

A plea for first-principles radiative models in solar energetic events 

Marian Lazar, Rodrigo A Lopez, Shaaban M Shaaban, and Stefaan Poedts

Radio emissions have a wide exploitation potential both in the remote diagnosis of their plasma sources, often impossible to explore in-situ, but also in the context of space weather for developing realistic forecasting models for the effects of energetic solar events, such as coronal plasma ejections (CMEs) on modern technologies on ground and in space. Here we discuss the importance of first-principle radiative models, not only for these applications but especially for developing realistic models for type-II and type-III radio emissions whose plasma sources are likely to be explored in situ by different satellites and spacecraft. At this early stage, first-principle radiative models combine a fundamental kinetic theory for describing wave instabilities in plasma sources, with numerical simulations of their saturation by nonlinear processes that generate free-propagating radio waves. We also discuss a series of further additions, in particular with nonlinear theories of the various wave-wave couplings responsible for the generation of radio emissions.

How to cite: Lazar, M., Lopez, R. A., Shaaban, S. M., and Poedts, S.: A plea for first-principles radiative models in solar energetic events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12703, https://doi.org/10.5194/egusphere-egu24-12703, 2024.

EGU24-13385 | Posters on site | ST1.7 | Highlight

Solar wind flows across the solar activity cycle, connectivity and plasma signatures on and off the ecliptic plane 

Rui Pinto, Alexis Rouillard, and Mikel Indurain

We investigate the evolution of  spatial distribution of solar wind sources by means of an extended time series of data-driven 3D simulations that cover solar 2 activity cycles. We examine the corresponding solar wind acceleration profiles as a function of source latitude and time, and highlight consequences for the interpretation of Parker Solar Probe (PSP) and Solar Orbiter (SolO) in-situ measurements. We relate magnetic connectivity jumps with solar wind plasma signatures, and discuss their occurrence frequency and amplitudes at different epochs of the solar cycle, on and off the ecliptic plane.
We also indicate impacts on the rotation profile of the solar corona and on the occurrence of regions of enhanced poloidal and toroidal flow shear that can drive plasma instabilities.  Finally, we search for and test geometrical parameters alternative to the standard ones currently used in semi-empirical solar wind forecasting methods.

How to cite: Pinto, R., Rouillard, A., and Indurain, M.: Solar wind flows across the solar activity cycle, connectivity and plasma signatures on and off the ecliptic plane, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13385, https://doi.org/10.5194/egusphere-egu24-13385, 2024.

EGU24-13818 | Orals | ST1.7

Comprehensive Analysis of a Type III Radio Storm Using Multi-Spacecraft Observations 

Vratislav Krupar, Oksana Kruparova, Adam Szabo, and David Lario Loyo

Solar flares are often accompanied by intense radio emissions, particularly notable in the form of fast-drifting type III bursts. These bursts are generated by suprathermal electron beams that are accelerated at solar flare reconnection sites. These electron beams travel outward along open magnetic field lines, passing through the corona and interplanetary medium. Type III Radio Storms, characterized by nearly continuous type III radio burst activity, can persist for hours or days. This study reports on a significant type III storm observed between 2023-09-20 and 2023-09-27, observed simultaneously by STEREO-A and Parker Solar Probe. During this interval, the spacecraft were longitudinally separated by 5 to 45 degrees, providing a unique opportunity to examine both radial and longitudinal variations in type III storms. Additionally, the Solar Orbiter's position on the opposite side of the Sun, complemented by SDO data, enabled nearly 360-degree solar coverage in EUV during this event. This extensive coverage allowed for the correlation of individual radio bursts with EUV images, offering a comprehensive view of the full Sun. Our findings contribute to the understanding of solar flare dynamics and electron beam propagation in solar eruptions.

How to cite: Krupar, V., Kruparova, O., Szabo, A., and Lario Loyo, D.: Comprehensive Analysis of a Type III Radio Storm Using Multi-Spacecraft Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13818, https://doi.org/10.5194/egusphere-egu24-13818, 2024.

EGU24-14105 | ECS | Orals | ST1.7

Localising Signatures of Particle Acceleration During Solar Flare in Low Solar Atmosphere Using Combined EUV, X-ray and Radio Observations 

Shilpi Bhunia, Laura Hayes, Karl Ludwig Klein, Peter T. Gallgaher, Shane Maloney, and Nicole Vilmer

It is well known that flare-accelerated electrons can produce hard X-ray (HXR) emission and Type-III radio bursts. The HXR emission is produced by the accelerated electrons propagating towards the chromosphere where they deposit their energy. In contrast, Type-III radio bursts are produced by the accelerated electron beams traveling toward the outer solar atmosphere. Hence a temporal correlation between these two kinds of emission may imply a common origin of the accelerated electrons providing insight into the acceleration process, and allowing us to connect electrons at the Sun to those in the heliosphere On 2022-Nov-11 11:30 - 12:00 UT, the Spectrometer Telescope for Imaging X-rays (STIX) on Solar Orbiter observed a highly energetic flare event with an excellent time resolution of 0.5 s. Simultaneously there were observations of multiple coronal and interplanetary Type-III radio bursts from several instruments such as WIND/WAVES, I-LOFAR, and ORFEES spanning the frequency range from 1 - 1000 MHz.We find an excellent temporal correlation between the X-ray and radio time series. We do multiwavelength imaging analysis using AIA, STIX, and NRH to locate the acceleration origin and track the electron beams during the eruption.



How to cite: Bhunia, S., Hayes, L., Klein, K. L., Gallgaher, P. T., Maloney, S., and Vilmer, N.: Localising Signatures of Particle Acceleration During Solar Flare in Low Solar Atmosphere Using Combined EUV, X-ray and Radio Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14105, https://doi.org/10.5194/egusphere-egu24-14105, 2024.

EGU24-14421 | ECS | Posters virtual | ST1.7 | Highlight

First robust detection of linear polarization from solar radio bursts 

Soham Dey, Devojyoti Kansabanik, Surajit Mondal, and Divya Oberoi

For decades, the focus of polarimetric solar radio studies has been solely on circular polarization. This stemmed from the fact that the strong differential Faraday rotation in coronal plasma should completely obliterate any linear polarization component even if it were to be present (e.g., Grognard & McLean, 1973). Consequently, after a few reports in the late 50s and early 60s of successful detection of linearly polarized radio emissions from the Sun, the  consensus has essentially been to dismiss any detected linear polarization in the observed dynamic spectra as instrumental artifacts (e.g., Grognard & McLean, 1972; Boischot & Lecacheux, 1975). This assumption has been routinely used in calibrating solar polarimetric observations, even for recent studies (Morosan et al. 2022). The state-of-the-art polarimetric calibration algorithm, P-AIRCARS (Kansabanik et al., 2022a, 2022b, 2023) does not rely on any such assumptions. It provides high-fidelity and high-dynamic-range spectropolarimetric snapshot solar radio images using a new-generation instrument, the Murchison Widefield Array (MWA). This enables us to explore a part of phase space which was hitherto unexplored.

Using P-AIRCARS and the MWA, we present the first robust imaging-based evidence for linearly polarized emission in metre-wavelength solar radio bursts. This finding is corroborated by simultaneous observations with the upgraded Giant Metrewave Radio Telescope at the same spectral band. Moreover, our estimated upper limit on the Rotation Measure (RM) of ~50 rad m-2 are orders of magnitude lower than the previous estimates based on coronal models (e.g., ~103 rad m-2 by Bhonsle & McNarry, 1964). This low RM implies that the linear polarized emission has traversed much lower electron column densities, suggesting that it originates at much higher coronal heights. Interestingly, detections of linear polarization in stellar radio bursts have also been reported recently (Callingham et al., 2021; Bastian et al., 2022). We conclude by exploring some physical scenarios which can potentially give rise to such linearly polarized emissions in the solar corona.

How to cite: Dey, S., Kansabanik, D., Mondal, S., and Oberoi, D.: First robust detection of linear polarization from solar radio bursts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14421, https://doi.org/10.5194/egusphere-egu24-14421, 2024.

EGU24-15960 | ECS | Posters virtual | ST1.7

First detailed polarimetric study of a type-II solar radio burst with the Murchison Widefield Array 

Puja Majee, Devojyoti Kansabanik, and Divya Oberoi

Type-II solar radio bursts are plasma emissions generated by magnetohydrodynamic shocks that are predominantly driven by coronal mass ejections (CMEs), the most potent drivers of space weather. These narrow-bandwidth (~few MHz) emissions show slow drift towards lower frequencies in the dynamic spectrum and appear at the fundamental and harmonic of the local plasma frequency. The evolution and geo-effectiveness of CMEs are governed by their magnetic fields and interaction with the coronal magnetized plasma. Therefore, understanding the CME-entrained magnetic fields and the ambient medium is important. Polarimetric properties of type-II bursts provide promising diagnostics for measuring and understanding the magnetic field strength, and topology at the CME-shocks. In the literature, their polarization properties have been reported to vary from being unpolarized to very strongly circularly polarized, and no linear polarization has ever been reported. The vast majority of these studies rely on dynamic spectra which can only provide spatially integrated information. Instruments like Murchison Widefield Array (MWA) and robust spectropolarimetric snapshot solar imaging pipeline, P-AIRCARS, (Kansabanik et al., 2022, 2023) have enabled high-fidelity and high-dynamic range solar radio imaging with good temporal, spectral and reasonable angular resolution. Benefiting from these, we have used the MWA to carry out detailed imaging polarimetric characterization of a type-II solar radio burst. We detect a weak circular polarization of ~ 4% during the type II. We also report the first imaging detection of low levels of linearly polarized type-II emission. This robust but surprising detection goes against the conventional wisdom that differential coronal Faraday rotation should wipe out any linear polarization signatures in coronal emissions. We characterize the polarimetric structures in both circular and linear polarizations, meticulously investigating their temporal and spectral evolutions. Our study marks the start of the use of polarimetric imaging observations to further the understanding of type-II radio bursts and coronal propagation.  

How to cite: Majee, P., Kansabanik, D., and Oberoi, D.: First detailed polarimetric study of a type-II solar radio burst with the Murchison Widefield Array, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15960, https://doi.org/10.5194/egusphere-egu24-15960, 2024.

EGU24-16041 | ECS | Orals | ST1.7

On the evolution of magnetic reconnection in the solar wind 

Naïs Fargette, Jonathan Eastwood, Cara Waters, Benoit Lavraud, Stefan Eriksson, Tai Phan, Marit Oieroset, Julia Stawarz, and Luca Franci

Magnetic reconnection is a fundamental process in astrophysical plasma, as it enables the dissipation of energy at kinetic scales as well as large-scale reconfiguration of the magnetic topology. In the solar wind, its quantitative role in plasma dynamics and particle energization remains an open question that is starting to come into focus as more missions now probe the inner heliosphere. To more efficiently detect magnetic reconnection in-situ using automated and modern methods is one of the challenges that can bring us closer to understanding the impact of magnetic reconnection on its surrounding magnetized environment.

In this presentation, we make use of existing databases to focus on the evolution of magnetic reconnection properties through the heliosphere, using several space missions such as Parker Solar Probe (PSP), Solar Orbiter and Wind. We investigate the properties of small-scale reconnecting current sheets found in the turbulent solar wind as a function of radial distance and plasma source. In parallel, we also make use of PSP-Solar Orbiter alignments to study how the large-scale and high-shear reconnection occurring at the heliospheric current sheet evolves as it propagates in the solar wind. Finally, we emphasize how reconnection has a high impact on coherent structure evolution such as coronal mass ejection erosion or merging.

Collectively, these results show that magnetic reconnection is ubiquitous in the solar wind and occurs in a wide variety of settings, with a high impact on its surrounding environment. We discuss how the recent growth of available in-situ spacecraft mission data inside the Earth orbit promises further substantial progress in our understanding of magnetic reconnection occurrence, properties and impact in the solar wind. 

How to cite: Fargette, N., Eastwood, J., Waters, C., Lavraud, B., Eriksson, S., Phan, T., Oieroset, M., Stawarz, J., and Franci, L.: On the evolution of magnetic reconnection in the solar wind, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16041, https://doi.org/10.5194/egusphere-egu24-16041, 2024.

EGU24-18676 | ECS | Posters on site | ST1.7

Forecasting solar wind speed from coronal holes and active regions 

Daniel Collin, Yuri Shprits, Stefano Bianco, Fadil Inceoglu, Stefan Hofmeister, and Guillermo Gallego

Coronal holes (CHs) have long been known as one of the main sources of high-speed solar wind streams, but recent evidence suggests that active regions (ARs) also play a significant role as solar wind sources. In this study, we aim to investigate the impact of both CHs and ARs as source regions of the solar wind. Both structures can be identified in extreme ultra-violet (EUV) solar images several days before they become geoeffective. We exploit this relation to construct a model that forecasts the solar wind speed at L1. First, we accurately detect and track the evolution of CHs and ARs over time by employing a segmentation algorithm on solar images. Next, we extract features from the indicated regions in EUV images and magnetograms, such as area and location of the source regions and the corresponding magnetic field configurations. These features, along with solar wind data from previous solar rotations and the current state of the solar cycle, are assimilated over time in a data-driven model that predicts the hourly solar wind speed at L1 four days in advance. During model training, we particularly focus on preserving the distribution of observed solar wind speeds to overcome a common drawback of data-driven solar wind speed prediction models, namely the underprediction of the peak values of solar storms. By adding a suitable regularization to the loss function, we force our model to follow the physical behavior more closely, which results in a significantly improved accuracy for predicting solar storms. Finally, we use our model to draw conclusions about the physical relevance of CHs and ARs for solar wind speed models. The model's performance is evaluated through cross-validation on 14 years of data and compared to other state-of-the-art models.

How to cite: Collin, D., Shprits, Y., Bianco, S., Inceoglu, F., Hofmeister, S., and Gallego, G.: Forecasting solar wind speed from coronal holes and active regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18676, https://doi.org/10.5194/egusphere-egu24-18676, 2024.

Detailed interferometric radio observations of solar activity allow us to constrain the dynamics of high-energy electron beams accelerated in flares and coronal mass ejections (CME). We have studied in detail the small-scale solar radio bursts, which accompanied one of the three homologous solar eruptions that originated from the western solar limb on November 04, 2015. We have used interferometric observations from the Murchison Widefield Array to image the multi-frequency emission in several radio channels between 80 and 300 MHz with 1-second resolution and 20 arcsec-pixels. The event began with a strong type II radio burst, and was followed by a separation of the emission into stationary and moving sources, the latter clearly related to the propagating CME structure. The observations show simultaneous multi-frequency flickering of intensity along a persistent off-limb structure related to the CME-driven shock wave, connecting the stationary and moving sources. This flickering emission persisted for more than 30 minutes. We present an analysis of its dynamics, its relation to the CME flux rope, the expected magnetic configurations, and electron beam properties. These observations provide valuable information about the evolution and kinematics of the CME in its early stages. 

How to cite: Kozarev, K.: Dynamics of Persistent Low-Frequency Radio Pulsations During the November 04, 2015 CME, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18797, https://doi.org/10.5194/egusphere-egu24-18797, 2024.

EGU24-19133 | Posters on site | ST1.7

Radio Investigations for Space Environment Research (RISER): An Overview 

David Barnes, Mario Bisi, Richard Fallows, Biagio Forte, Steve Milan, David Jackson, Bernard Jackson, Dusan Odstrcil, and Oyuki Chang

Coronal Mass Ejections (CMEs), and ever-changing solar wind conditions, drive processes in the Earth’s space-environment (the magnetosphere and ionosphere) which can strongly affect satellite communications, navigation systems, and power grids upon which society relies. Mitigation strategies are heavily dependent on accurate forecasting of the likely impact of space-weather conditions on operations. The tracking of plasma structures, and turbulence within, in the inner-heliosphere is now made possible by the LOw Frequency ARray (LOFAR, the world’s largest low-frequency radio-telescope) through observations of the scintillation of radio waves from astronomical sources propagating through these plasma structures. Information obtained through LOFAR can be augmented with in situ measurements from existing missions and the planned ESA Vigil mission to be stationed at L5, as well as other remote-sensing techniques, to provide an unprecedented advance warning of space weather detrimental to society. The Radio Investigations for Space Environment Research (RISER) project will provide a comprehensive understanding of the Earth’s space-environment through the use of novel radio observations and modelling techniques to investigate coupling between solar-driven inner-heliospheric structures and the Earth.

 

RISER will address the following key questions in the space-weather domain:

  • How can we better attribute magnetospheric-ionospheric response to inner-heliospheric variability?

  • How well can we establish a direct connection between parameters that characterise structures in the inner-heliosphere with the geo-effectiveness of geomagnetic disturbances?

  • How can we identify and track plasma structures in the inner-heliosphere using scintillation data from low-frequency radio telescopes in a systematic way before they reach Earth?

  • What is the value of improved forecasts of adverse space weather conditions when using radio-telescope observations and enhanced science of the inner heliosphere- magnetosphere-ionosphere system?

     

    Here, we give an overview of RISER, its high-level objectives, the importance and relevance to advancing our understanding of space-weather science and impacts, as well as a brief overview of the LOFAR-UK upgrades.

How to cite: Barnes, D., Bisi, M., Fallows, R., Forte, B., Milan, S., Jackson, D., Jackson, B., Odstrcil, D., and Chang, O.: Radio Investigations for Space Environment Research (RISER): An Overview, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19133, https://doi.org/10.5194/egusphere-egu24-19133, 2024.

EGU24-20004 | Orals | ST1.7

Study of Dynamics and Evolution of Solar Wind during BepiColombo and Solar Orbiter Radial Alignment 

Pier Paolo Di Bartolomeo, Tommaso Alberti, Anna Milillo, Luca Giovannelli, Ali Varsani, Gunter Laky, Alessandro Aronica, Simone Benella, Raffaella D'Amicis, Daniel Heyner, Adrian Kazakov, Valeria Mangano, Stefano Massetti, Martina Moroni, Raffaella Noschese, Stefano Orsini, Christina Plainaki, Roberto Sordini, and Mirko Stumpo

The spacecraft radial alignment geometry is useful and intriguing for examining the solar wind’s radial evolution by observing a plasma parcel at varying helio- centric distances. This study focuses on the radial alignment between the Bepi- Colombo and Solar Orbiter (SolO) spacecraft. Utilizing particle and magnetic field data from both spacecraft, we initially characterize particle distribution and interplanetary magnetic field topology at 0.31 AU for BepiColombo and 0.67 AU for SolO. We identified the same magnetic field configuration measured at both locations by considering the propagation time shift.

The magnetic field observations from onboard magnetometers on both space- craft have been used to delve into the nonlinear energy cascade mechanism and the intricate organization of magnetic field fluctuations, which govern the energy transfer rate and dissipation behavior. Additionally, we conduct a comparative analysis of flux data recorded by the Planetary Ion CAMERA (PICAM) of the SERENA (Search for Exospheric Refilling and Emitted Natural Abundances) suite for BepiColombo and the Proton Alpha Sensor (PAS) of the SWA (Solar Wind Analyser) suite.

This comprehensive study aims to create a valuable tool for in-depth analysis with aligned configurations. Moreover, it seeks to integrate fluid and magnetic investigations. For the first time, we utilize BepiColombo data to advance our comprehension of the radial evolution of solar wind plasma.

How to cite: Di Bartolomeo, P. P., Alberti, T., Milillo, A., Giovannelli, L., Varsani, A., Laky, G., Aronica, A., Benella, S., D'Amicis, R., Heyner, D., Kazakov, A., Mangano, V., Massetti, S., Moroni, M., Noschese, R., Orsini, S., Plainaki, C., Sordini, R., and Stumpo, M.: Study of Dynamics and Evolution of Solar Wind during BepiColombo and Solar Orbiter Radial Alignment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20004, https://doi.org/10.5194/egusphere-egu24-20004, 2024.

EGU24-260 | ECS | Posters on site | ST1.9

A turbulent dynamo threshold in the shell-model approximation. 

Ilyas Abushzada and Egor Yushkov

Turbulent magnetic dynamo models were created about fifty years ago to describe the growth of the average magnetic energy in random convective plasma flows. A typical feature of such models is the generation threshold, when the exponential growth of magnetic energy begins only at sufficiently large magnetic Reynolds numbers Rm. In particular, one of the first models, proposed in the 70th by Kazantsev and Kraichnan, predicts a generation threshold in the region of Reynolds numbers of the order of 100. This threshold is difficult to achieve even for modern laboratory experiments, and therefore many studies in recent years have been devoted to clarifying this critical value. However, there is a sufficient disadvantage of usually used turbulent dynamo model – the assumption about delta-correlated in time random velocity field. This nonphysical assumption makes one unconfident in the correctness of the estimate of the dynamo threshold. In this work, using shell MHD models, we are trying to find out how accurate Kazantsev’s estimate of the generation threshold is, and how this threshold depends on the flow velocity, diffusion coefficients, and hydrodynamic helicity. This work was supported by the BASIS Foundation grant no. 21-1-3-63-1.

How to cite: Abushzada, I. and Yushkov, E.: A turbulent dynamo threshold in the shell-model approximation., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-260, https://doi.org/10.5194/egusphere-egu24-260, 2024.

The Solar Orbiter (SO) mission provides a unique opportunity to study the evolution of turbulence in the solar wind across different distances from the sun and different plasma conditions. We use SO observations of extended intervals of homogeneous solar wind turbulence to investigate under what conditions the turbulent cascade in the solar wind is supported by either, or both of two distinct phenomenologies, (i) wave- wave interactions and (ii) coherent structure formation and interaction.

We identify nine Solar Orbiter observations of extended intervals of homogeneous solar wind turbulence where each interval is over 10 hours long without current-sheet crossings and other large events. We perform a systematic scale-by-scale decomposition of the observed magnetic field using two wavelets that are known to discriminate between wave-packets and discontinuities, the Daubechies 10 (Db10) and Haar respectively.

A characteristic of turbulence is that the probability distributions (pdfs) of fluctuations obtained on small scales exhibit extended supra-Gaussian tails, and as the scale is increased, the moments decrease and there is ultimately a cross-over to Gaussian pdfs at the outer scale of the turbulence. Using quantile quantile plots, we directly compare the fluctuations pdfs obtained from Haar and Db10 decompositions. This reveals three distinct regimes of behaviour. On larger scales, deep within the inertial range (IR), both the Haar and Db10 decompositions give essentially the same fluctuation pdfs. On the smallest scales, deep within the kinetic range (KR), the pdfs are distinct in that the Haar wavelet fluctuations have a much broader distribution, and the largest fluctuations are associated with coherent structures. On intermediate scales, that span the IR-KR scale break identified from the power spectra, the pdf is composed of two populations, a core with a common pdf functional form for the Haar and Db10 fluctuations, and extended tails where the Haar fluctuations dominate. This establishes a cross-over between wave-packet dominated phenomenology in the IR, to coherent structure dominated phenomenology in the KR. We find that the intermediate range of scales is quite narrow around 0.9 au so that the crossover from wave-packet to coherent structure dominated phenomenology is quite abrupt. At around 0.3au, the crossover occurs over a broader range of scales extending down to the 0.25s scale and up to 4s.

As coherent structures and wave-wave interactions have been proposed as candidates to mediate the turbulent cascade, these results offer new insights into the evolution of the turbulent cascade with distance from the sun.

How to cite: Bendt, A., Chapman, S., and Dudok de Wit, T.: The relative prevalence of wave-packets and coherent structures in the inertial and kinetic ranges of turbulence as seen by Solar Orbiter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1136, https://doi.org/10.5194/egusphere-egu24-1136, 2024.

EGU24-4307 | Posters on site | ST1.9

Magnetic field and ion velocity spectra in the solar wind from inertial to kinetic scales 

Jana Safrankova, Zdenek Nemecek, Alexander Pitna, Frantisek Nemec, and Luca Franci

The paper analyzes the power spectra of solar wind velocity and magnetic field fluctuations that are computed in the frequency range around the break between inertial and kinetic scales. The study uses measurements of the Bright Monitor of the Solar Wind (BMSW) on board Spektr-R with a time resolution of 32 ms complemented with 10 Hz magnetic field observations from Wind propagated to the Spektr-R location and compare them with observations of Solar Orbiter and Parker Solar Probe closer to the Sun. We concentrate on the ion kinetic scale and investigate statistically the role of parameters like the fluctuation amplitudes of parallel and perpendicular magnetic field components, collisional age, temperature anisotropy or ion and electron beta. Our discussion encompasses the interplay of magnetic field and plasma fluctuations that characterize this dynamic environment and reveals that although the ion beta controls a position of the spectral break between the inertial and kinetic ranges, other mentioned parameters determine the steepness of the kinetic range spectrum of both quantities. We are showing that these statistical results are in line with theoretical considerations.

How to cite: Safrankova, J., Nemecek, Z., Pitna, A., Nemec, F., and Franci, L.: Magnetic field and ion velocity spectra in the solar wind from inertial to kinetic scales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4307, https://doi.org/10.5194/egusphere-egu24-4307, 2024.

The solar wind flowing from the solar corona at supersonic and super-Alfvénic speeds is the subject of intense research at present. Numerous studies focused on temporal variability of plasma parameters, crucial to define solar wind plasma, showed that spectral distributions exhibit Power-law dependence. Additionally, examinations of its fluctuations revealed a distinctive evolution in shape of PDF’s shifting from Gaussian (Maxwellian) to peaked and heavy-tailed distributions, towards smaller scales. 

Turbulence stands as a complex, nonlinear, and multiscale phenomenon, based on a sophisticated cascade theory. While its complete description remains an unsolved challenge, various statistical methods such as structural functions or power spectra offer partial insights. Although the well-established Kolmogorov theory (K41) holds in the inertial region of magnetized plasma [10.1103/PhysRevE.78.026414], its applicability at smaller scales or higher frequencies is known to be an exception. Thus, alternative methods, such as a kinetic treatment, should be considered. 

Common approaches rely on various plasma parameters and processes, limiting their applicability in highly dynamic turbulence like the solar wind. Consequently, an alternative approach based on the framework of stochastic processes theory, particularly Markov processes, has been introduced to characterize energy transfer across the turbulent cascade. Statistical evidence suggests that turbulence has Markov properties. Furthermore, the differential equation of the Markov process can be extracted directly from data. Estimation of the Kramers-Moyal coefficients plays a pivotal role in discerning the form of the Fokker-Planck (or equivalently Langevin) equation that governs the evolution of the PDF with scale for the increments. Models based on a drift force and diffusion strength depending on scale have been emerging as a viable approach for elucidating the dynamics of solar wind turbulence, hence this method can be considered as a junction between the statistical and dynamical analysis.

Based on the data collected by the Magnetospheric Multiscale (MMS) mission’s satellites, we delve into the subject of turbulence on inertial, sub-ion, and kinetic scales. Building upon prior Markovian analysis of turbulence of the transfer of magnetic-to-magnetic field fluctuations in the near-Earth space environment [10.1093/mnras/stad2584, 10.3847/1538-4357/aca0a0], we also extend our investigation to ion velocity-to-velocity and magnetic-to-velocity cases. However, we direct our focus towards the purer statistical facet of the analysis, joint with the elements of dynamical approach. We analyze whether the transfer of increments exhibits `local` or `non-local` character, which in this context, they describe the scales involved in interactions that lead to the turbulent cascade. Additionally, we observe a global scale-invariance in relation to the Fokker-Planck equation, for a magnetic field case. 

Finally, we briefly discuss a potential non-parametric approach, namely a stochastic dynamical jump-diffusion model, or alternatively a multi-fractal approach, which can be useful to describe the underlying process accurately. We believe that such a comparative approach spanning diverse conditions is meaningful, as it aims to unveil any underlying universality within the statistical properties of the near-Earth solar wind space plasma at the intricate kinetic and sub-ion scales.

Acknowledgments: This work has been supported by the National Science Centre, Poland (NCN), through grant No. 2021/41/B/ST10/00823.

How to cite: Wójcik, D. and Macek, W. M.: Probing Small Scale Solar Wind Turbulence: Markovian Analysis and Scale Interactions from Inertial to Kinetic Regimes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6582, https://doi.org/10.5194/egusphere-egu24-6582, 2024.

EGU24-7031 | ECS | Orals | ST1.9

Significant Enhancement of Turbulence Cascade Rates Downstream of Quasi–perpendicular Bow Shock at Mars 

Wence Jiang, Hui Li, Lina Hadid, Nahuel Andrés, Verscharen Daniel, and Chi Wang

Compressible plasma turbulence is prevalent in planetary plasma environments. However, our current understanding of turbulence injection and dissipation in the highly-compressible magnetosheath is still quite limited. Previous studies have suggested that pickup ion instabilities originating from the far-extended neutral exospheres of Mars may contribute to energy injection, leading to the frequent observation of plateau-like spectral characteristics in the Martian magnetosheath. Nonetheless, it remains unclear how the turbulence cascade rates vary with local parameters related to the bow shock geometry and pickup ions. In this investigation, we conduct a joint analysis of Tianwen-1 and MAVEN data to unveil spectral characteristics and the varying turbulence cascade rates under different bow shock geometries. By employing the exact laws of compressible magnetohydrodynamics turbulence, we observe a systematic increase in cascade rates with the shock normal angle. As the geometry transitions from quasi-parallel to quasi-perpendicular, the ratio between the turbulence cascade rates of the upstream solar wind and the downstream magnetosheath increases by 20-30 times. Furthermore, we find that the turbulence cascade rate of cases exhibiting plateau-like spectral shapes increases more significantly with the shock normal angle compared to those without plateau-like features. Our findings offer new insights into understanding turbulence injection and dissipation downstream of collisionless super-critical bow shocks in space and astrophysical plasmas.

How to cite: Jiang, W., Li, H., Hadid, L., Andrés, N., Daniel, V., and Wang, C.: Significant Enhancement of Turbulence Cascade Rates Downstream of Quasi–perpendicular Bow Shock at Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7031, https://doi.org/10.5194/egusphere-egu24-7031, 2024.

EGU24-7045 | Orals | ST1.9

Nature of temperature intermittency in the solar wind turbulence 

Xin Wang, Yuxin Wang, and Haochen Yuan

In the solar wind turbulence, proton temperature fluctuations are highly intermittent, especially at small scales in the inertial range. This phenomenon may contain information about solar wind intermittent heating. However, the physical nature of the temperature intermittency is not yet clear. Based on the measurements from Solar Orbiter between 2020 and 2023, we identify temperature intermittent structures in the fast and slow solar wind, respectively. We compare the nature and kinetic effects of them. According to the variations of proton temperature and magnetic field when the temperature intermittency occurs, we classify the temperature intermittency in the fast wind into the following five categories: (1) 20% of the cases are identified as linear magnetic holes with local temperature enhancement, and a majority of them are unstable to mirror-mode (MM) instability. (2) 18% are related to tangential current sheets also with local temperature enhancement. (3) 9% are tangential discontinuities with a temperature interface, which could separate two different parcels of plasma. (4) 15% of the cases are accompanies by local temperature decrease that may be also due to MM instability. (5) 25% of the cases show a chain of magnetic field variations probably related to Alfven vortices. In the slow wind, the situation is different. The temperature intermittent structures are mainly associated with firehose instability. These results will help to further understand the intermittent dissipation process in the solar wind turbulence.

How to cite: Wang, X., Wang, Y., and Yuan, H.: Nature of temperature intermittency in the solar wind turbulence, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7045, https://doi.org/10.5194/egusphere-egu24-7045, 2024.

We present wave and turbulence observations by the DSCOVR spacecraft during solar flare and CME events. Over 9-day period, the spectral indices within the magnetic field power spectral density (PSD) in the RTN and mean-field-aligned (MFA) coordinates do not agree. In the inertial range the transverse PSD follows a Kraichnan–Iroshinikov -3/2 index when in MFA coordinates, while in the RTN frame the same PSD is more complex showing Kolmogorov -5/3 index at lower frequencies followed by a shallow index close to -1 at the inertial subrange before steepening to -2 close to the He+ cyclotron frequency. We show that the differences are due to the changing interplanetary magnetic field (IMF) direction relative to the solar wind velocity within the CME periods. We present evidence of wave-wave modulation and suggest that lower frequency waves in the solar wind can modulate the growth rates/propagation of ion cyclotron waves providing a method to transfer energy in the solar wind to smaller scales. Furthermore, we suggest that the Kraichnan–Iroshinikov -3/2 index in the inertial range can be explained by combining containment due to wave generation/propagation and stochastic Brownian motion in the solar wind. When these two phenomena are equal, they combine to create a -3/2 index.

How to cite: Loto'aniu, P. and Krista, L.: Spectral Indices and Evidence of Wave-Wave Modulation in Observations of the Interplanetary Magnetic Field, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7101, https://doi.org/10.5194/egusphere-egu24-7101, 2024.

EGU24-9272 | Posters on site | ST1.9 | Highlight

The French contribution for the NASA HelioSwarm mission 

Olivier Le Contel, Benoit Lavraud, Alessandro Retino, Matthieu Kretzschmar, Vincent Génot, Olga Alexandrova, Malik Mansour, Carine Amoros, Guillaume Jannet, Rituparna Baruah, Fatima Mehrez, Thierry Camus, Dominique Alison, Alexander Grigoriev, Claire Revillet, Marina Studniarek, Laurent Mirioni, Clémence Agrapart, Gérard Sou, and Nicolas Geyskens and the HelioSwarm team

The HelioSwarm mission was selected as a MIDEX mission by NASA in February 2022 for launch in 2029 with a nominal duration of 15 months. Its main objectives are to reveal the 3D spatial structure and dynamics of turbulence in a weakly collisional plasma and to investigate the mutual impact of turbulence near boundaries (e. g., Earth’s bow shock and magnetopause) and large-scale structures evolving in the solar wind (e. g., coronal mass ejection, corotating interaction region). The HelioSwarm mission will also contribute to the space weather science and to a better understanding of the Sun-Earth relationship. It consists of a platform (Hub) and eight smaller satellites (nodes) evolving along an elliptical orbit with an apogee ~ 60 and a perigee ~15 Earth radii. These 9 satellites, three-axis stabilised, will provide 36 pair combinations and 126 tetrahedral configurations covering the scales from 50~km (subion scale) to 3000 km (MHD scale). It will be the first mission able to investigate the physical processes related to cross-scale couplings between ion and MHD scales by measuring, simultaneously at these two scales, the magnetic field, ion density and velocity variations. Thus each satellite is equipped with the same instrument suite. A fluxgate magnetometer (MAG from Imperial College, UK) and a search-coil magnetometer (SCM) provide the 3D measurements of the magnetic field fluctuations whereas a Faraday cup (FC, SAO, USA) performs the ion density and velocity measurements. In addition, the ion distribution function is measured at a single point onboard the Hub by the iESA instrument, allowing to investigate the ion heating in particular. The SCM for HelioSwarm provided by LPP and LPC2E is strongly inherited of the SCM designed for the ESA JUICE mission. It will be mounted at the tip of a 3m boom and will cover the frequency range associated with the ion and subion scales in the near-Earth environment [0.1-16Hz] with the following sensitivities [15pT/√Hz at 1 Hz and 1.5 pT/√Hz at 10 Hz]. The iESA, developped by IRAP and LAB, is inherited from the PAS instrument operating on the ESA Solar Orbiter mission. It will provide the ion distribution function at high time and angular resolutions, respectively 0.150 s and 3°. Furthermore the energy range will be ~200 eV to 20 keV with 8% energy resolution. Status of the development of SCM and iESA prototypes will be presented.

How to cite: Le Contel, O., Lavraud, B., Retino, A., Kretzschmar, M., Génot, V., Alexandrova, O., Mansour, M., Amoros, C., Jannet, G., Baruah, R., Mehrez, F., Camus, T., Alison, D., Grigoriev, A., Revillet, C., Studniarek, M., Mirioni, L., Agrapart, C., Sou, G., and Geyskens, N. and the HelioSwarm team: The French contribution for the NASA HelioSwarm mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9272, https://doi.org/10.5194/egusphere-egu24-9272, 2024.

EGU24-10703 | Posters on site | ST1.9

Analysis Techniques for Future Multipoint, Multiscale Observatories 

Kristopher Klein and Theodore Broeren

Turbulence is three-dimensional, multiscale disorder. Characterizing turbulence requires determining how energy is injected into, transported through, and removed from these systems. One can study the three-dimensional structure by using measurements from at least four spatial points combined with appropriate analysis approaches to estimate spatial gradients and distributions of power at a given scale. Such techniques have been applied to data from spacecraft missions such as MMS and Cluster, but are limited to a single scale associated with the average inter-spacecraft distance. Given that future selected and proposed spacecraft missions, including HelioSwarm and Plasma Observatory, will have many more than four measurement points, with separations between the spacecraft spanning different characteristic spatial scale lengths, we consider the extension of previously implemented analysis techniques to these multipoint, multiscale configurations. In particular, we consider the propagation of measurement error through the wave telescope technique as a function of the number of measurements points and configuration to demonstrate the impact on accurate resolution of the underlying wavevectors. We also explore the optimal selection of subsets of measurement points to more accurately measure the properties of plane waves and wave packets with wavevectors spanning the spatial scales encompassed by a representative multispacecraft observatory.

How to cite: Klein, K. and Broeren, T.: Analysis Techniques for Future Multipoint, Multiscale Observatories, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10703, https://doi.org/10.5194/egusphere-egu24-10703, 2024.

EGU24-11006 | Orals | ST1.9 | Highlight

Transverse energy injection scales at the base of the solar corona 

Richard Morton and Rahul Sharma

Alfvén wave turbulence models are the foundation of many investigations into the winds and EUV/X-ray emission from cool, solar-like stars. The models are used to estimate mass loss rates, magnetic spin down and exoplanet habitability. However, the models currently rely on ad-hoc estimates of critical parameters. One such parameter is the perpendicular correlation length, L (the energy injection length scale), whose value has significant influence over the turbulent heating and mass loss rates. Using the Coronal Multi-channel Polarimeter, a ground based corona-graph, we provide the first measurements of the correlation length of Alfvénic waves at the base of the corona. Our analysis shows the values are broadly homogeneous through the corona and have a distribution sharply peaked around 7.6 - 9.3 Mm. The measured correlation length is comparable to the expected scales associated with supergranulation. The results also suggest a discrepancy between the coronal values of L, theoretical transport models for the evolution of L with distance from the Sun, and previous estimates of L beyond the Alfvén critical zone. We suggest a thesis as to the missing physics.

How to cite: Morton, R. and Sharma, R.: Transverse energy injection scales at the base of the solar corona, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11006, https://doi.org/10.5194/egusphere-egu24-11006, 2024.

EGU24-13061 | Posters on site | ST1.9

New Insights on Solar Wind Electrons at 1 AU: Collisionality, Heat Flux, and Thermal Force 

Chadi Salem, Marc Pulupa, Daniel Verscharen, and Peter Yoon

The origin and evolution of non-equilibrium characteristics of electron velocity distribution functions (eVDFs) in the solar wind are still not well understood. They are key in understanding heat conduction and energy transport in weakly collisional plasma, as well as in the scenario at the origin of the solar wind. Due to low collision rates in the solar wind, the electron populations develop temperature anisotropies and velocity drifts in the proton frame, as well as suprathermal tails and heat fluxes along the local magnetic field direction. These non-thermal characteristics are highly variable, and the processes that control them remain an open question.  

We present here a recent work on enhanced measurements of solar wind eVDFs from Wind at 1AU. This work is based on a sophisticated algorithm that calibrates eVDFs with plasma Quasi Thermal Noise data in order to accurately and systematically characterize the non-thermal properties of the eVDFs, as well as those of their Core, Halo and Strahl components.  Indeed, the core, halo and strahl populations are fitted to determine their densities, temperatures and temperature anisotropies as well as their respective drift velocities with respect of the ion velocity (or solar wind speed).  The density, temperature and temperature anisotropy, as well as the parallel heat flux of the total eVDFs are also computed. 

We use a 4-year-long dataset composed of all these parameters at solar minimum to enable statistically significant analyses of solar wind electron properties. We estimate collisional proxies such as collisional age and Knudsen number, and discuss usually neglected effects. In addition to the total electron heat flux, we also compute the heat flux contributions from the core, halo and strahl and discuss the interplay between these three components.  We finally show estimates of the so-called Thermal Force, a drag or Coulomb friction between ions and the electron components that arises naturally from the non-thermal character of the eVDFs, even in the absence of current. This TF enhances the parallel electric field and plays an important, but usually neglected, role in two fluid energy transfers between electrons and ions. It is parallel to the heat flux that causes it, however its role in understanding the observed heat flux remains to be explored.  This statistically-significant work allows a local, quantitative measure of Coulomb coupling that maybe important with possibly other microphysical processes to locally control non-thermal properties.

How to cite: Salem, C., Pulupa, M., Verscharen, D., and Yoon, P.: New Insights on Solar Wind Electrons at 1 AU: Collisionality, Heat Flux, and Thermal Force, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13061, https://doi.org/10.5194/egusphere-egu24-13061, 2024.

EGU24-13402 | ECS | Orals | ST1.9 | Highlight

Energy transfer in the Solar Wind: The interplay between turbulence and kinetic instabilities. 

Simon Opie, Daniel Verscharen, Christopher Chen, Christopher Owen, Philip Isenberg, Luca Sorriso-Valvo, Luca Franci, and Lorenzo Matteini

Precisely how and where energy transfer between scales in the Solar Wind takes place remains an open question. We use the occurrence of conditions predicted by linear theory to promote the growth of kinetic instabilities, to infer how turbulence drives temperature anisotropies. We analyse Solar Orbiter data by applying the measure of local energy transfer (LET) derived from the Politano and Pouquet exact law to identify the relative distributions of energy transfer processes in the solar wind. We quantify these processes with the application of a radial rate of strain computed from single spacecraft data, a measure that we define as an approximation of the strain rate in fully three-dimensional turbulence. We find good agreement with the theoretical prediction that velocity shear is responsible for driving temperature anisotropies. We conclude that the turbulent velocity field plays a key role in the creation of unstable conditions in the Solar Wind.

How to cite: Opie, S., Verscharen, D., Chen, C., Owen, C., Isenberg, P., Sorriso-Valvo, L., Franci, L., and Matteini, L.: Energy transfer in the Solar Wind: The interplay between turbulence and kinetic instabilities., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13402, https://doi.org/10.5194/egusphere-egu24-13402, 2024.

EGU24-15798 | ECS | Orals | ST1.9

On the Cascade-Dissipation Balance in Astrophysical Plasmas 

Davide Manzini, Fouad Sahraoui, and Francesco Califano

The differential heating of electrons and ions by turbulence in weakly collisional magnetized plasmas and the scales at which such energy dissipation is most effective are still debated. Using a large data sample measured in the Earth’s magnetosheath by the Magnetospheric Multiscale mission
and the coarse-grained energy equations derived from the Vlasov-Maxwell system we find evidence of a balance over two decades in scales between the energy cascade and dissipation rates. The decline of cascade rate at kinetic scales (in contrast with a constant one in the inertial range), is balanced by increasing ion and electron heating rates, estimated via the pressure-strain. Ion scales are found to contribute most effectively to ion heating, while electron heating originates equally from ion and electron scales. These results can potentially impact the current understanding of particle heating in turbulent magnetized plasmas as well as their theoretical and numerical modeling.

How to cite: Manzini, D., Sahraoui, F., and Califano, F.: On the Cascade-Dissipation Balance in Astrophysical Plasmas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15798, https://doi.org/10.5194/egusphere-egu24-15798, 2024.

EGU24-17557 | Posters on site | ST1.9

Embedded coherent structures from MHD to sub-ion scales in turbulent solar wind: PSP observations at 0.17 au 

Olga Alexandrova, Alexander Vinogradov, Pascal Demoulin, Anton Artemyev, Milan Maksimovic, Andre Mangeney, and Stuart Bale

We study intermittent coherent structures in solar wind magnetic turbulence from MHD to kinetic plasma scales using  Parker Solar Probe data during its first perihelion (at 0.17 au). These structures are energetic events localized in time and covering wide range of scales. We detect them using Morlet wavelets. For the first time, we apply a multi-scale analyses in physical space to study these structures. At large MHD scales, we find (i) current sheets including switchback boundaries and (ii) Alfvén vortices. Within these large scale events, there are  embedded structures at smaller scales: typically  Alfvén vortices at ion scales and a compressible vortices at sub-ion scales. To quantify the relative importance of different type of structures, we do a statistical comparison of the observed structures with the expectations of models of the current sheets and vortices. This comparison is based on amplitude anisotropy of magnetic fluctuations within the structures. The results show the dominance of Alfvén vortices at all scales in contrast to the widespread view of dominance of current sheets. The number of coherent structures grows from the MHD to the sub-ion scales. For one MHD scale structure there are ∼10 ion scale structures and ∼50  sub-ion scale structures. In general, there are multiple structures of ion and sub-ion scales embedded within one MHD structure. There are also examples of non-embedded structures at ion and sub-ion scales.

How to cite: Alexandrova, O., Vinogradov, A., Demoulin, P., Artemyev, A., Maksimovic, M., Mangeney, A., and Bale, S.: Embedded coherent structures from MHD to sub-ion scales in turbulent solar wind: PSP observations at 0.17 au, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17557, https://doi.org/10.5194/egusphere-egu24-17557, 2024.

EGU24-17726 | ECS | Posters on site | ST1.9

Radial Distribution of Electron Quasi-thermal Noise in the Outer Heliosphere 

Yi-Lun Li, Ling Chen, and De-Jin Wu

The Voyager 1 and 2 are only the two spacecraft that have arrived and passed through the heliospheric boundaries. Based on the plasma data from Voyager 2 spacecraft, the electron quasi-thermal noise (QTN) is investigated by using of the electron population model consisting of a core with Maxwellian distribution and a halo with kappa distribution. The power spectra of the electron QTN is calculated at different heliocentric distances from 1 AU to 110 AU. The parametric dependence of the QTN power spectra and the effective Debye length on the model parameters, such as the density ratio and temperature ratio of the halo to the core, kappa index and the antenna length, are discussed further. The results show that the electron QTN spectrum consists of a plateau in the low frequency band f < fpt, a prominent peak at the plasma frequency fpt, and a rapid decreasing part in the high frequency band f > fpt. The QTN plateau level basically falls down outwards until the termination shock crossing at about 84 AU, after which the plateau rebounds a little near the heliopause. Although the model parameters can be very variable, the QTN plateau level does not present more than the double change in a fairly wide range of the model parameters. The presented results can be useful for future deep-space explorations in the heliosphere and can provide valuable references for the design of onboard detectors.

How to cite: Li, Y.-L., Chen, L., and Wu, D.-J.: Radial Distribution of Electron Quasi-thermal Noise in the Outer Heliosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17726, https://doi.org/10.5194/egusphere-egu24-17726, 2024.

EGU24-17757 | Orals | ST1.9

An unbiased view of the contributions to turbulence cascade in Earth's magnetosheath. 

Victor Montagud-Camps, Sergio Toledo-Redondo, Petr Hellinger, Andrea Verdini, Emanuele Papini, Julia Stawarz, Luca Sorriso-Valvo, Inmaculada F. Albert, and Aida Castilla

Earth's magnetosheath is a medium where plasma parameters can take a wide range of values and where plasma fluid properties can vary greatly, depending on the distance to the bow shock and the upstream solar wind conditions. Plasma turbulence that develops in the magnetosheath is also affected by these changes, thus giving rise to a similar variety of turbulence regimes.

With the data collected during the MMS unbiased magnetosheath campaign, it is now possible to explore the plasma parameter space of the magnetosheath and study turbulence properties with a set of high-cadence in-situ measurements. This dataset was gathered from February 1st 2023 to April 1st 2023 and consists of 15 inbound magnetosheath crossings from which 300 burst-data intervals were collected. During each crossing, the burst-mode measurements were taken for 3 minutes every 6 minutes, without imposing any selection criteria to collect the data. The length of the time intervals and their time resolution make them suitable to study the turbulent dynamics around the ion spectral break.

In this work we will study the different contributions to the energy cascade rate (measured by means of scaling laws derived from the Hall-MHD equations) and their dependence on plasma conditions, like the plasma beta, and turbulence properties, such as the spectral index and turbulence anisotropy.

How to cite: Montagud-Camps, V., Toledo-Redondo, S., Hellinger, P., Verdini, A., Papini, E., Stawarz, J., Sorriso-Valvo, L., F. Albert, I., and Castilla, A.: An unbiased view of the contributions to turbulence cascade in Earth's magnetosheath., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17757, https://doi.org/10.5194/egusphere-egu24-17757, 2024.

EGU24-20199 | Orals | ST1.9 | Highlight

Inverse and Forward Alfvenic Kármán Vortex and Magnetospheric Coherent Turbulent Structures in 3D Global MHD Simulations 

DongSheng Cai, Shigeru Fujita, and Bertrand Lembege

Magnetospheric coherent structures related to the dynamics of the dayside magnetopause frontier for a northward IMF configuration, are analyzed using global 3D MHD simulations. The main goal is to reach a synthetic scenario on the formation of 3D unstable/stable structures developed in different steps from the dayside to the night side. They are: (i) the Kelvin-Helmholtz (K-H) vortexes are generated along and outside the magnetopause near the dayside region, while other K-H vortexes are generated along and inside the magnetopause;  (ii) Those vortexes frozen to the magnetic field  at the inner sides of the magnetopause at both dusk/dawn sides extend towards the north and south.  They face each other near the north and south ionosphere with counter inverse rotation to form the so-called “inverse” Karman vortexes; (iii) both rows of vortexes are shed off soon from the magnetopause; (iii) these vortexes are unstable in one each row, adjust, and evolve into a marginal stable Kármán vortex street; (iv) these Kármán vortexes soon are reformed into stable longitudinal (stream-wise) coherent vortexes and survive for long time over large distances x~-130 to -140Re in the magnetotail. All these processes lead to the formation of magnetospheric coherent turbulent structures. 

How to cite: Cai, D., Fujita, S., and Lembege, B.: Inverse and Forward Alfvenic Kármán Vortex and Magnetospheric Coherent Turbulent Structures in 3D Global MHD Simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20199, https://doi.org/10.5194/egusphere-egu24-20199, 2024.

EGU24-20578 | Posters on site | ST1.9

Unified Alfven Wave Turbulence Based Model for Energy and Particle Transport in Solar Corona and Heliosphere 

Igor Sokolov, Arcadi Usmanov, Bart van der Holst, and Tamas Gombosi

The existing Alfven Wave Turbulence Based Solar Atmosphere Model (AWSoM) as used in the SWMF framework of the University of Michigan to simulate the Solar Corona and Inner Heliosphere (i.e. to 1 AU heliocentric distance) meets an ideological problem while compared with the equations for turbulence usually employed in modeling the outer heliosphere (i.e. beyond 1 AU). While for the turbulence in the outer heliosphere the energy difference (the difference between the averaged kinetic and magnetic energy densities) is used as one of the Reynolds-averaged quantity describing the local state of turbulence, the present AWSoM model lacks the energy difference at all. 

Besides an evident inconsistency between the models of turbulence, employing the different sets of variables below and beyond 1 AU, to have a full description of turbulence is important by two reasons, both relating to the charged particle transport producing the radiation hazards in space. First, for simulation both solar energetic particle and galactic cosmic rays at 1 AU a computational domain should extend at least to 2-3 AU. Second, even if below 1 AU the energy difference effect on turbulence might be negligible and not necessary to be included into the turbulence model, it is still needed to calculate transport coefficients for the high energy charged particles in the turbulent magnetic field. To evaluate it from the averaged quantities characterizing the turbulence, both the total energy density and the said energy difference are needed. 

In the presented research, an extra equation for the energy difference in introduced and solved in such way that at small heliocentric distances the turbulence model reduces to that used in the AWSoM with no loss in generality. On the other hand at larger heliocentric distances it becomes very close (if not identical) to the typical outer heliosphere model. In addition to averaged energetic characteristics of turbulence we evaluate the correlation spatial scales for directions parallel and perpendicular to the averaged interplanetary magnetic field was well as the transport coefficients for high-energy charged particles

How to cite: Sokolov, I., Usmanov, A., van der Holst, B., and Gombosi, T.: Unified Alfven Wave Turbulence Based Model for Energy and Particle Transport in Solar Corona and Heliosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20578, https://doi.org/10.5194/egusphere-egu24-20578, 2024.

EGU24-85 | Posters on site | ST1.10

Upstream plasma waves and downstream magnetic reconnection at a reforming quasi-parallel shock 

Quanming Lu, Ao Guo, Zhongwei Yang, San Lu, and Rongsheng Wang

With the help of a two-dimensional (2-D) particle-in-cell (PIC) simulation model, we investigate the long-time evolution of a quasi-parallel shock. Part of upstream ions are reflected by the shock front, and their interactions with the incident ions excite low-frequency magnetosonic waves in the upstream. Detailed analyses have shown that the dominant wave mode is caused by the resonant ion-ion beam instability, and the wavelength can reach tens of the ion inertial lengths. Although these plasma waves are directed toward the upstream in the upstream plasma frame, they are brought by the incident plasma flow toward the shock front, and their amplitude is enhanced during the approaching. The interaction of the upstream plasma waves with the shock leads to the cyclic reformation of the shock front. When crossing the shock front, these large-amplitude plasma waves are compressed and evolve into current sheets in the transition region of the shock. At last, magnetic reconnection occurs in these current sheets, accompanying with the generation of magnetic islands. Simultaneously, there still exist another kind of plasma waves with the wavelength of several ion inertial lengths in the ramp of the shock. The current sheets in the transition region are distorted and broken into several segments when this kind of plasma waves are transmitted into the downstream, where magnetic reconnection and the generated islands have a much smaller size.

How to cite: Lu, Q., Guo, A., Yang, Z., Lu, S., and Wang, R.: Upstream plasma waves and downstream magnetic reconnection at a reforming quasi-parallel shock, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-85, https://doi.org/10.5194/egusphere-egu24-85, 2024.

EGU24-1836 | Posters on site | ST1.10

Statistical Study of Electron Kinetic Entropy Generation at Earth's Quasi-perpendicular Bow Shock 

Martin Lindberg, Alice Wallner, Sofie Berglund, and Andris Vaivads

We use the Magnetospheric Multiscale mission to study electron kinetic entropy across Earth's quasi-perpendicular bow shock. We perform a statistical study of how the change in electron entropy depends on the different plasma parameters associated with a collisionless shock crossing. We find that the change in electron entropy exhibits strong correlations with upstream electron plasma beta, Alfvén Mach number, and electron thermal Mach number. The source of entropy generation is investigated by correlating the change in electron entropy across the shock to the measured electric and magnetic field wave power strengths for different frequency intervals within different regions in the shock transition layer. The electron entropy change is observed to be greater for higher electric field wave power within the shock ramp and shock foot for frequencies between the lower hybrid frequency and electron cyclotron frequency. This implies electrostatic waves are important for electron kinetic entropy generation at Earth's quasi-perpendicular bow shock but also for the non-adiabatic electron heating at quasi-perpendicular shocks.

How to cite: Lindberg, M., Wallner, A., Berglund, S., and Vaivads, A.: Statistical Study of Electron Kinetic Entropy Generation at Earth's Quasi-perpendicular Bow Shock, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1836, https://doi.org/10.5194/egusphere-egu24-1836, 2024.

EGU24-2111 | ECS | Orals | ST1.10

Magnetosheath dynamic pressure enhancements associated with a solar wind rotational discontinuity: Results from a hybrid-Vlasov simulation 

Jonas Suni, Minna Palmroth, Lucile Turc, Markus Battarbee, Yann Pfau-Kempf, Maxime Dubart, Urs Ganse, Leo Kotipalo, Vertti Tarvus, and Abiyot Workayehu

When plasma and magnetic field discontinuities in the solar wind interact with Earth’s magnetic field, they can significantly alter the properties and dynamics of Earth’s bow shock, magnetosheath, and magnetopause. In this study, we investigate magnetosheath dynamic pressure enhancements generated by the interaction between a solar wind rotational discontinuity with Earth’s bow shock in a 2D simulation run of the global magnetospheric hybrid-Vlasov model Vlasiator. We find that as the discontinuity is advected into the bow shock, several fast-mode pulses associated with enhanced dynamic pressure are launched toward the Earth. In addition, the interaction between discontinuity and shock generates transient enhancements of dynamic pressure at the bow shock that move Earthward together with the discontinuity. We find that the fast-mode pulses are able to traverse the magnetosheath and disturb the magnetopause. This finding differs from the results of previous studies using 2D and 3D MHD simulations as well as spacecraft measurements, which concluded that magnetopause disturbances should be caused by the rotational discontinuity itself and the dynamic pressure enhancement associated with it.

How to cite: Suni, J., Palmroth, M., Turc, L., Battarbee, M., Pfau-Kempf, Y., Dubart, M., Ganse, U., Kotipalo, L., Tarvus, V., and Workayehu, A.: Magnetosheath dynamic pressure enhancements associated with a solar wind rotational discontinuity: Results from a hybrid-Vlasov simulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2111, https://doi.org/10.5194/egusphere-egu24-2111, 2024.

EGU24-2220 | Posters on site | ST1.10

Helium pickup ion 3D velocity distributions at interplanetary shocks 

Keiichi Ogasawara, Harald Kucharek, Berndt Klecker, Maher Dayeh, and Robert Ebert

3D velocity distribution functions (VDFs) of He+ pickup ions (PUIs) were used to trace local physical processes around interplanetary shocks. He+ PUIs are measured by PLasma And SupraThermal Ion Compostion (PLASTIC) instrument onboard the Solar Terrestrial Relations Observatory (STEREO) in an unprecedented cadence and angular/velocity resolutions with mass and charge state unambiguously determined. We focused on the VDFs in terms of the interplanetary magnetic field orientation in the solar wind frame and indipendently evaluated the acceleration, heating, and pitch-angle scattering for both perpendicular and parallel shocks with notable differences. For the perpendicular shock: (a) Reflected and energized particles were found in the upstream, and the PUI properties were isolated between upstream and downstream, (b) Strong heating is observed in the sheath region, (c) Suprathermal particles are found in the sheath region and attributed to the compression within the solar wind, and (d) Universal pitch-angle scattering were found through out the ICME. For the parallel shock: (a) Locaized heating and acceleration were found around the shock location, (b) Harder suprathermal particle distributions were found near the shock, suggesting diffusive shock processes, (c) Weak or no sheath heating was observed, and (d) Pitch angle scattering were correlated with magnetic field power spectral density at the Helium cyclotron.

How to cite: Ogasawara, K., Kucharek, H., Klecker, B., Dayeh, M., and Ebert, R.: Helium pickup ion 3D velocity distributions at interplanetary shocks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2220, https://doi.org/10.5194/egusphere-egu24-2220, 2024.

EGU24-3121 | ECS | Posters on site | ST1.10

Statistical study of SLAMS at the Martian foreshock 

Tsz Kiu Wong Chan, Tomas Karlsson, and Sofia Bergman

Properties of the region upstream of planetary bow shocks depend strongly on the direction of the interplanetary magnetic field. For quasi-parallel bow shocks, part of the solar wind ions are reflected back upstream from the shock and this reflected ion population triggers instabilities resulting in a turbulent region. In the quasi-parallel case, reflected particles travel far upstream, creating an extended turbulent foreshock region. Within this region, Short Large-Amplitude Magnetic Structures (SLAMS) can frequently be found, which are suggested to play a pivotal role in the formation of planetary bow shocks. Yet many properties of SLAMS are not well known at Earth and even less so at other planets.

Here we present results on the occurrence and other properties of SLAMS at the Martian foreshock with the help of magnetic field and ion data from NASA's Mars Atmosphere and Volatile Evolution Mission (MAVEN). SLAMS are identified by three criteria. First, a magnetic field three times stronger than the background magnetic field is required. Second, SLAMS should have an elliptic polarization so that it can be differentiated from a shock oscillation. Last, it takes place upstream of the bow shock. The results presented here can offer comparative insights with SLAMS at Earth for exploring potential dependencies on system size and other magnetospheric parameters.

How to cite: Wong Chan, T. K., Karlsson, T., and Bergman, S.: Statistical study of SLAMS at the Martian foreshock, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3121, https://doi.org/10.5194/egusphere-egu24-3121, 2024.

EGU24-3125 | ECS | Posters on site | ST1.10

Statistical properties of Short Large-Amplitude Magnetic Structures (SLAMS) in the foreshock region of Earth 

Sofia Bergman, Tomas Karlsson, and Tsz Kiu Wong Chan

Short Large-Amplitude Magnetic Structures (SLAMS) are common magnetic field signatures observed in the foreshock region of collisionless quasi-parallel shocks. SLAMS are non-linear isolated structures, defined to have an amplitude of more than 2 times the background magnetic field. They have been suggested to grow from ultra-low frequency (ULF) waves that are common in the foreshock region, and are believed to play important roles in the formation of quasi-parallel shocks, influencing the properties and dynamics of the shock and also associated particle energization.   

In this work, we use data from the Cluster and Magnetospheric Multiscale (MMS) missions to statistically study the properties of SLAMS in the foreshock region of Earth. We use an automated method to detect SLAMS in the data, producing a comprehensive database of SLAMS detections. The size, morphology and propagation velocity of SLAMS are then studied using statistical approaches, investigating the dependence on several parameters, such as amplitude, upstream conditions and distance from the bow shock. 

How to cite: Bergman, S., Karlsson, T., and Wong Chan, T. K.: Statistical properties of Short Large-Amplitude Magnetic Structures (SLAMS) in the foreshock region of Earth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3125, https://doi.org/10.5194/egusphere-egu24-3125, 2024.

EGU24-3342 | ECS | Orals | ST1.10 | Highlight

Magnetosheath jets at jupiter and across the solar system 

Yufei Zhou, Savvas Raptis, Shan Wang, Chao Shen, Nian Ren, and Lan Ma

The study of jets downstream of Earth's bow shock has been a subject of extensive investigation for over a decade due to their close connection with shock dynamics and their profound impact on the geomagnetic environment. While the variability of the solar wind and its interaction with Earth's magnetosphere provide valuable insights into jets across a range of parameters, a broader parameter space can be explored by examining the downstream of other planetary bow shocks. Here we report the existence of anti-sunward and sunward jets downstream of Jovian bow shock and show their close association to magnetic discontinuities. The anti-sunward jets are possibly generated by a shock--discontinuity interaction. Finally, through a comparative analysis of jets observed at Earth, Mars, and Jupiter, we show that the size of jets scales with the size of bow shock.

How to cite: Zhou, Y., Raptis, S., Wang, S., Shen, C., Ren, N., and Ma, L.: Magnetosheath jets at jupiter and across the solar system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3342, https://doi.org/10.5194/egusphere-egu24-3342, 2024.

EGU24-3966 | Posters on site | ST1.10

Hybrid simulations of multiple reflection of protons and heavy ions at Earth’s bow shock 

Imogen Gingell and Hadi Madanian

Ion reflection is known to be a key component of particle energisation and heating in super-critical collisionless shockwaves. As a source of free energy, reflected ions drive stream instabilities in the shock foot, create magnetic perturbations, and contribute to magnetic field amplification in the upstream and downstream regions of quasi-perpendicular shocks. Where ions reflect from the shock ramp multiple times, a longer dwell time in the shock foot allows for more opportunities for interaction with non-stationary and turbulent shock processes, which can result in injection into processes such as diffusive shock acceleration and shock drift acceleration. To characterise the pathway to multiple ion reflection, we perform a series of 2D and 3D hybrid particle-in-cell simulations (fluid electron, particle ions) over a parameter range typical of Earth’s bow shock, varying Mach number, plasmas betas, and the angle between the shock normal and upstream magnetic field (θBn). This enables a parametric investigation of the density fraction of multiply reflected ions both upstream and downstream of the shock, for protons and for heavier ion components of the solar wind such as He2+. We discuss methods for identification of multiply-reflected ions in kinetic plasma simulations, corresponding analogues for observations (where available), and investigate their impact on shock energetics. By examining the partial moments of reflected ions in two- and three-dimensional simulations, we also explore which shock processes drive multiple reflection.

How to cite: Gingell, I. and Madanian, H.: Hybrid simulations of multiple reflection of protons and heavy ions at Earth’s bow shock, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3966, https://doi.org/10.5194/egusphere-egu24-3966, 2024.

EGU24-4145 | Posters on site | ST1.10

Hot Flow Anomalies Delimiting Traveling Foreshocks 

Primoz Kajdic, Xochitl Blanco-Cano, Diana Rojas Castillo, Martin Archer, Lucile Turc, Yann Pfaum-Kempf, Adrian LaMoury, Terry Liu, Savvas Raptis, Marcos Vinicius, Sun Lee, Yao Shutao, Yufei Hao, David Sibeck, Hui Zhang, Nojan Omidi, Boyi Wang, Yu Lin, and Philippe Escoubet

Transient upstream mesoscale structures (TUMS) are an important topic in the field of research of the near-Earth environment. These events form upstream of the Earth's bow shock and can perturb regions downstream it, i.e. magnetosheath and magnetopause. They can even affect the magnetosphere and ionosphere causing a range of space weather phenomena during periods without noticeable solar activity. There is still much to learn about the TUMS and the way they interact with the near-Earth environment. We are only beginning to understand how the different types of the TUMS relate to each other. In the past it has been shown that traveling foreshocks may contain foreshock cavitons, spontaneous hot flow anomalies and foreshock compressional boundaries (FCB). Here we present the first evidence, that traveling foreshocks may be bounded on at least one of their edges by hot flow anomalies (HFA) and by events that look like hybrids between HFAs and FCBs. We show two case studies observed by the Cluster and MMS constellations. Such studies enable us to better understand all the ways in which the solar-terrestrial interactions occur.

How to cite: Kajdic, P., Blanco-Cano, X., Rojas Castillo, D., Archer, M., Turc, L., Pfaum-Kempf, Y., LaMoury, A., Liu, T., Raptis, S., Vinicius, M., Lee, S., Shutao, Y., Hao, Y., Sibeck, D., Zhang, H., Omidi, N., Wang, B., Lin, Y., and Escoubet, P.: Hot Flow Anomalies Delimiting Traveling Foreshocks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4145, https://doi.org/10.5194/egusphere-egu24-4145, 2024.

Dynamic pressure variations that are upstream from the magnetopause can interact with the coupled magnetospheric and ionospheric system, causing significant auroral responses, which indicates magnetospheric compressions, wave propagations and disturbances of current system. Recent studies have shown that not only large-scale solar wind structures but also locally-generated foreshock transients can be associated with strong dynamic pressure variations and further induce such auroral responses. However, how these auroral responses evolve in 2D perspective and how the corresponding current system and electron precipitation evolve in 2D perspective are still unclear. Thus, in our study, we used the coordinated observations between THEMIS probes and the ground-based all-sky images at South Pole to statistically investigate the 2D evolution of discrete and diffuse auroral responses to both solar wind structures and foreshock activities. The discrete auroral evolution shows that the dynamic pressure variations upstream from the magnetopause can induce upward field-aligned currents near the magnetopause in the magnetosphere. These currents can extend earthward and most of them extend duskward, causing the bifurcation of auroral oval. The diffuse auroral patterns reveal that in the ionosphere, the area with compression-related electron precipitations propagates poleward. The azimuthal motion of compression-related electron precipitations can be either dawnward or duskward, depending on the azimuthal propagation of the magnetospheric compressions. We further found that the location, size and associated dynamic pressure change of the upstream solar-wind or foreshock transients can modify the shape and 2D evolution of the corresponding auroral patterns.

How to cite: Wang, B. and Xu, X.: The 2D evolution of the M-I responses to solar wind/foreshock transients based on the coordinated observation between THEMIS and ground-based ASI, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5084, https://doi.org/10.5194/egusphere-egu24-5084, 2024.

EGU24-5564 | ECS | Orals | ST1.10

Scale Size Estimation of Magnetosheath Jets 

Adrian Pöppelwerth, Georg Glebe, Johannes Z. D. Mieth, Florian Koller, Tomas Karlsson, Zoltan Vörös, and Ferdinand Plaschke

Transient enhancements in the dynamic pressure, so-called magnetosheath jets or simply jets, are abundant in the magnetosheath.
They propagate from the bow shock towards the magnetopause. On their way through the magnetosheath, jets interact with the
ambient plasma. The scale size of jets is determined almost exclusively with statistical studies, but not for individual jet events.
We use multipoint measurements from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission
to study the passage of a single jet and obtain its size. We observe an evasive motion of the plasma on the jet path. Using this
flow pattern we can reconstruct the position of the central axis of this jet along its propagation direction. This allows us to
estimate the spatial distribution of the dynamic pressure within the jet. Furthermore, the size perpendicular to the
propagation direction can be estimated for different cross sections. Using this method, the scale size of individual jet events
can be determined with multiple spacecraft. In principle, only two spacecraft are needed if we assume a simplified geometry.
In the case we investigated, both the dynamic pressure and the perpendicular size increase along the propagation axis from
the front part towards the center of the jet and decrease again towards the rear part.

How to cite: Pöppelwerth, A., Glebe, G., Mieth, J. Z. D., Koller, F., Karlsson, T., Vörös, Z., and Plaschke, F.: Scale Size Estimation of Magnetosheath Jets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5564, https://doi.org/10.5194/egusphere-egu24-5564, 2024.

EGU24-6483 | Posters on site | ST1.10

Spontaneous Hot Flow Anomalies at Earth’s foreshock. 

Xochitl Blanco-Cano, Diana Rojas-Castillo, and Primoz Kajdic

In recent years we have learnt that foreshock transients play an influential role in solar wind coupling with Earth’s magnetosphere. These transients include Spontaneous Hot Flow Anomalies (SHFAs) which are characterized by dips in magnetic field magnitude and ion density, enhanced temperature, and are surrounded by ultra low frequency waves. SHFAs share some characteristics with hot flow anomalies but their formation mechanism does not require a discontinuity in the solar wind.  SHFAs evolve from caviton interaction with backstreaming ions. We use Cluster and MMS magnetic field and plasma data to study SHFAs internal structure and their evolution. We find that SHFA can occur not only deep in the foreshock as initially thought, but they can also been observed near the foreshock boundary where higher frequency waves (f ∼ 1 Hz) exist. We also investigate the properties of velocity distribution functions inside these transients, and their influence on bow shock structure.

How to cite: Blanco-Cano, X., Rojas-Castillo, D., and Kajdic, P.: Spontaneous Hot Flow Anomalies at Earth’s foreshock., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6483, https://doi.org/10.5194/egusphere-egu24-6483, 2024.

EGU24-7538 | ECS | Orals | ST1.10

Ion acceleration due to highly sheared tangential discontinuities at quasi-perpendicular shocks 

Konrad Steinvall and Imogen Gingell

Collisionless shocks are efficient particle accelerators. While ion acceleration by shocks has been intensively studied using spacecraft data and numerical models, the main focus has been on the case of a steady upstream. In the steady upstream case, it has been shown that quasi-parallel shocks are much more efficient ion accelerators than quasi-perpendicular shocks. However, the solar wind is in general highly dynamic, containing current sheets which correspond to a magnetic shear. In this study we use a local 2.5D hybrid particle-in-cell (particle ions, fluid electrons) model to study how the ion acceleration of quasi-perpendicular shocks is affected when the upstream contains highly sheared tangential discontinuities. We show that, even in the absence of foreshock transients, the current sheets can cause a significant increase in the flux of high-energy ions. The acceleration can be explained by the following simple model. When the upstream TD is close to the shock, the shock-reflected ions can cross it during the upstream part of their gyro–motion. After crossing the TD, the large magnetic shear, corresponding to a sign change of the magnetic field direction, results in a meandering ion trajectory. This motion takes the ion further upstream, where it is further energized by the upstream convection electric field. The net effect of this process is a local ion acceleration efficiency of a few %, as quantified as the fraction of energy (in the downstream and in the downstream frame) that is carried by ions with energies larger than 10 times the upstream bulk kinetic energy. This is comparable to the efficiency of quasi-parallel shocks in the case of a steady upstream. Such discontinuities can therefore be an important source of energetic ions at quasi-perpendicular shocks, even if no foreshock transient is formed.

How to cite: Steinvall, K. and Gingell, I.: Ion acceleration due to highly sheared tangential discontinuities at quasi-perpendicular shocks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7538, https://doi.org/10.5194/egusphere-egu24-7538, 2024.

EGU24-8084 | ECS | Posters on site | ST1.10

Solar wind deceleration in the foreshock as the source of the foreshock compressive structures 

Niki Xirogiannopoulou, Oleksandr Goncarov, Jana Safrankova, and Zdenek Nemecek

The foreshock is a turbulent region located upstream of the quasi parallel bow shock. It is dominated by waves and reflected back-streaming particles that interact with each other and result in the creation of different foreshock phenomena. Xirogiannopoulou et al. (2023) found that the deceleration of the solar wind in the foreshock region plays a major role in the creation of subsolar structures with enhanced density or/and magnetic field magnitude, like plasmoids, SLAMS and mixed structures. Moreover, they have found that their formation is increasing with increased velocity of the pristine solar wind. Previous studies, established that foreshock structures are connected with MSH jets (Raptis et al., 2022).  Simultaneously, Koller et al. (2023) researched the connection between the MSH jets and solar wind structures and concluded that the high-speed streams (HSS) create a more favorable environment for the jet creation. Following these results, we use measurements of the Magnetospheric Multiscale Spacecraft (MMS) and OMNI solar wind database between the years 2015 and 2018 and present a statistical analysis considering the presence of solar wind phenomena and their effect in the appearance rate of the compressive foreshock structures. We attempt to explore the origin of these structures and analyze their connection with the notable decrease (10–15 %) of the solar wind speed inside the foreshock region.

How to cite: Xirogiannopoulou, N., Goncarov, O., Safrankova, J., and Nemecek, Z.: Solar wind deceleration in the foreshock as the source of the foreshock compressive structures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8084, https://doi.org/10.5194/egusphere-egu24-8084, 2024.

EGU24-9451 | Posters on site | ST1.10

Wave Activities Throughout a Low-Mach Number Quasi-Parallel Shock: 2-D Hybrid Simulations  

Yufei Hao, Quanming Lu, Dejin Wu, and Liang Xiang

In this paper, two-dimensional hybrid simulations are used to study wave excitation and evolution throughout a low-Mach number quasi-parallel shock. Simulation results show that quasi-parallel fast magnetosonic waves, ion Bernstein waves with harmonics and possible Alfven/ion cyclotron waves can be excited in the upstream region, and their small phase velocities compared to injected flow velocity results in the convection to the shock front where they are mode converted into several groups of downstream waves, including Alfven waves along the directions parallel to downstream average magnetic fields and perpendicular to the shock normal, the quasi-perpendicular kinetic slow waves and possible kinetic Alfven waves. We suggest that downstream Alfven waves originate from the mode conversion of upstream quasi-parallel fast magnetosonic waves with left-hand polarization in the downstream rest frame under helicity conservation, while the downstream left-hand polarized kinetic slow waves and right-hand polarized kinetic Alfven waves can be from the upstream quasi-perpendicular ion Bernstein waves.

How to cite: Hao, Y., Lu, Q., Wu, D., and Xiang, L.: Wave Activities Throughout a Low-Mach Number Quasi-Parallel Shock: 2-D Hybrid Simulations , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9451, https://doi.org/10.5194/egusphere-egu24-9451, 2024.

EGU24-12210 | ECS | Orals | ST1.10

Solar Wind Structures Impacting the Plasma Stability and Ion Energy Distribution Downstream of the Terrestrial Bow Shock 

Florian Koller, Cyril Simon Wedlund, Manuela Temmer, Ferdinand Plaschke, Luis Preisser, Zoltan Vörös, Owen Wyn Roberts, Adrian Pöppelwerth, Savvas Raptis, and Tomas Karlsson

The plasma properties of the incoming solar wind undergo significant changes as they cross the terrestrial bow shock and traverse the magnetosheath. The solar wind itself can be categorized into different categories depending on their solar origin and linked to large-scale structures like coronal mass ejections (CMEs) or stream interaction regions (SIRs) detected in near-Earth space. Using measurements from THEMIS combined with OMNI data spanning from 2008 onward, we provide a statistical overview of temperature anisotropy-driven plasma instabilities in the dayside magnetosheath. This analysis is conducted under various upstream solar wind conditions and structures, which significantly impact the plasma environment in the magnetosheath. We extend this analysis to transient phenomena such as dynamic pressure enhancements in the magnetosheath (so-called jets) as well.

As a consequence of collisionless shock physics, the shocked plasma is expected to display vastly different behaviours in terms of plasma properties and stability when sorted into quasi-parallel and quasi-perpendicular downstream magnetosheath regions. However, this categorization is complicated by the presence of fast solar wind streams originating in solar coronal holes due to the significantly increased ion energy flux of the plasma. Consequently, in our statistical analysis, we emphasize the importance of magnetosheath classification under different solar wind plasma origins and show how stable the magnetosheath plasma is in any given upstream solar wind condition. Combining knowledge of solar wind origins and structures with shock and magnetosheath research can contribute to an improved classification of quasi-perpendicular and quasi-parallel shock conditions across all solar wind origins.

How to cite: Koller, F., Simon Wedlund, C., Temmer, M., Plaschke, F., Preisser, L., Vörös, Z., Roberts, O. W., Pöppelwerth, A., Raptis, S., and Karlsson, T.: Solar Wind Structures Impacting the Plasma Stability and Ion Energy Distribution Downstream of the Terrestrial Bow Shock, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12210, https://doi.org/10.5194/egusphere-egu24-12210, 2024.

We briefly summarize some of the latest, impactful results concerning the nature and physics of collisionless shock waves as observed by NASA’s Magnetospheric Multiscale (MMS) mission. MMS routinely observes Earth’s bow shock and also infrequently captures interplanetary shocks at 1 AU. With the four, identical observatories outfitted with a comprehensive payload of state-of-the-art plasma instrumentation, MMS offers unprecedented capabilities for studying the micro-to-global-scale nature of shocks in near-Earth space. New results highlighted include: the global energy budget and energy partitioning at Earth’s bow shock; complexity and significance of the quasi-parallel shock regime and the ion foreshock;  the acceleration of ions to >1 MeV and electrons to relativistic (>100 keV) energies; and kinetic-scale dynamics of shock fronts including reconnection and We finish with new results of an ongoing large-scale, statistical study of Earth’s bow shock empowered by machine learning applied to the full MMS dataset. We finish with a discussion of the upcoming MMS orbital configurations in regards of new studies plus idealized concepts for future missions to study collisionless shocks.

How to cite: Turner, D.: Insights on collisionless shock physics from the Magnetospheric Multiscale (MMS) mission at Earth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13539, https://doi.org/10.5194/egusphere-egu24-13539, 2024.

EGU24-14825 | ECS | Orals | ST1.10

Solar Wind Periodic Density Structures: Size Scales and Geo-effectiveness 

Simone Di Matteo, Christos Katsavrias, Larry Kepko, and Nicholeen Viall

Mesoscale transient structures affecting the solar wind-magnetosphere coupling can be either generated in the near-Earth environment or already present in the pristine solar wind. Among the solar wind mesoscale structures, in recent years, there has been a growing attention to Periodic Density Structures (PDSs), that are quasi-periodic enhancements of solar wind density ranging from a few minutes to a few hours. These structures have been extensively observed in remote sensing observations of the solar corona, and in in situ observations up to 1 AU where they manifest radial length scales (Lx) greater than or equal to the size of the Earth’s dayside magnetosphere, i.e., from tens to hundreds Earth’s radii (RE). The PDSs have significant impact on the dynamics of the Earth’s magnetosphere and space weather for example driving Ultra-Low-Frequency (ULF) waves and affecting the dynamics and precipitation of electrons in the outer radiation belt. One key aspect to understand the PDSs role in the dynamics of space weather is to characterize their 3D size scales. Current interplanetary multi-spacecraft observations mostly occur at spatial separations unable to measure the 3D size scale of PDSs. Here, we focused on high density slow solar wind intervals observed by the Wind and ARTEMIS-P1 spacecraft.  We classified solar wind parcels based on the occurrence or not of quasi periodic density enhancements. When both spacecraft observe PDSs, we further classify each interval based on the level of coherence of the relative periodicities. Combining our results with a simulation of PDSs transit, we provide, for the first time, an estimate of the PDSs azimuthal size scale, that is their extent in the direction perpendicular to the Sun-Earth direction. For two PDSs groups with radial length scales of Lx1≈86 RE and Lx2≈35 RE, we obtained azimuthal scales of Ly1≈340 RE and Ly2≈187 RE. After discussing the consequence of these findings in the context of solar wind-magnetosphere coupling, we remark that the magnetosphere response to PDS become even more relevant when these structures are compressed in Stream Interaction Regions (SIRs) creating larger fluctuations in solar wind density/dynamic-pressure. Finally, we select time intervals of PDSs in SIRs and, using GOES and RBSP constellations, we investigate the PDSs geo-effectiveness in term of ULF waves and outer belt/GEO electron response.

How to cite: Di Matteo, S., Katsavrias, C., Kepko, L., and Viall, N.: Solar Wind Periodic Density Structures: Size Scales and Geo-effectiveness, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14825, https://doi.org/10.5194/egusphere-egu24-14825, 2024.

EGU24-16745 | Posters on site | ST1.10

Ion dynamics in quasi-perpendicular nonstationary shocks: comparison between MMS observations and hybrid modeling 

Yuri Khotyaintsev, Daniel Graham, Domenico Trotta, Ahmad Lalti, and Andrew Dimmock

Reflection of a fraction of incoming ions is a vital dissipation mechanism for super-critical shocks. Such reflected ions provide a significant contribution to the downstream ion temperature increase. Understanding ion dynamics is crucial for the characterization of the shocks. It is needed to provide an equation of state that connects the upstream and downstream parameters for given shock parameters. The reflection depends on the detailed structure of the electromagnetic fields in the shock transition region. The ion-scale structure is strongly affected by the shock non-stationarity. To characterize the spatiotemporal evolution of the shock structure and ion reflection, we combine observations of several in-situ shock events by MMS with hybrid simulations performed for the specific parameters of the observed shocks. We find that the ion reflection is strongly affected by the structure imposed by the ripples. The reflection is very patchy, with regions of strong and weak ion reflection. 

How to cite: Khotyaintsev, Y., Graham, D., Trotta, D., Lalti, A., and Dimmock, A.: Ion dynamics in quasi-perpendicular nonstationary shocks: comparison between MMS observations and hybrid modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16745, https://doi.org/10.5194/egusphere-egu24-16745, 2024.

EGU24-16963 | ECS | Orals | ST1.10

Electron velocity-space scattering from whistler waves in the Earth’s magnetosheath 

Ida Svenningsson, Emiliya Yordanova, Yuri V. Khotyaintsev, Mats André, and Giulia Cozzani

Whistler waves are found in various space plasma environments, such as the Earth’s magnetosheath, where they affect particle dynamics and energy transfer. Through wave-particle interactions, they contribute to changes in both the energy and pitch angle of electrons. However, the significance of whistler waves in different plasma regions is not fully known.

In this work, we use MMS measurements to calculate the occurrence and properties of whistler waves in the Earth’s magnetosheath. Based on selected MMS orbits, we compare the plasma conditions offered by the more stationary quasi-perpendicular (Q) to the more fluctuating quasi-parallel (Q) magnetosheath. We show that the whistler waves occur in local magnetic dips and density peaks and are not necessarily correlated with electron temperature anisotropy. Also, there is an elevated occurrence downstream of Q shocks, compared to the Q configuration. Further, by calculating pitch-angle diffusion coefficients, we find that whistler waves can significantly reshape the electron velocity distribution during the time a plasma parcel spends in the magnetosheath, which has important implications for the plasma dynamics of the magnetosheath region.

How to cite: Svenningsson, I., Yordanova, E., Khotyaintsev, Y. V., André, M., and Cozzani, G.: Electron velocity-space scattering from whistler waves in the Earth’s magnetosheath, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16963, https://doi.org/10.5194/egusphere-egu24-16963, 2024.

EGU24-17436 | ECS | Posters on site | ST1.10

Electron heating at quasi-perpendicular collisionless shocks: adiabatic vs non-adiabatic  

Ahmad Lalti, Yuri V. Khotyaintsev, and Daniel B. Graham

The mechanism of electron heating across collisionless shocks remains an open question. The mechanisms suggested to address this problem revolve around the adiabatic or the non-adiabatic\stochastic dynamics of electrons across the shock. In this letter, we analyze the evolution of the electron velocity distribution function observed across 313 shocks with 1.7<MA<48. We use a Liouville mapping technique to show that the electron heating mechanism shifts from predominantly adiabatic to predominantly non-adiabatic as the Alfvenic Mach number in the de Hoffmann-Teller frame increases. We also show that for shocks with non-adiabatic heating of electrons, the heating mechanism is consistent with the stochastic shock drift acceleration (SSDA) mechanism.

How to cite: Lalti, A., Khotyaintsev, Y. V., and Graham, D. B.: Electron heating at quasi-perpendicular collisionless shocks: adiabatic vs non-adiabatic , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17436, https://doi.org/10.5194/egusphere-egu24-17436, 2024.

The day-to day variability of quiet-time ionosphere is surprisingly high even during periods of negligible solar forcing. Relatively well understood is the high-latitude variability where the solar wind is directly driving the high latitude currents, convection electric field or polar aurorae. But the current
understanding does not allow to accurately model the ionospheric state during the quiet-time conditions at mid- and low-latitudes. Surprising effects remain even at mid-latitudes, including for instance double daily maxima of ionospheric critical frequency.
European Space Agency's SWARM satellite constellation measurements allow the characterization of the upper atmospheric conditions and dynamics for already more than 10 years. The analysis of SWARM electron density and electric field data already showed that the ionosphere at mid-latitudes shows a non-negligible variability without a-priori solar driver, during negligible variations both in X-ray/EUV fluxes and missing disturbances in the solar wind. This often significant ionospheric variability currently remains unexplained, and further studies need to evaluate contributions by couplings from below comparing with those from above, i.e. checking the frequencies matching the foreshock waves with the local field-line resonances.

After efforts to properly select such "solar-quiet" periods, we compare the SWARM-detected variability trying to relate them to observations of magnetospheric ULF waves and configurations of the Earth foreshock mainly infered from the NASA's THEMIS satellite fleet and Wind solar wind observations.

How to cite: Urbar, J.: Evaluating the effects of the Earth's foreshock configurations on the "quiet-time" ionosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18654, https://doi.org/10.5194/egusphere-egu24-18654, 2024.

EGU24-20429 | Posters on site | ST1.10

A rotational discontinuity can generate both a foreshock bubble and a hot flow anomaly 

Lucile Turc, Martin Archer, Hongyang Zhou, Primoz Kajdic, Xochitl Blanco-Cano, Yann Pfau-Kempf, Terry Liu, Yu Lin, Nick Omidi, Adrian LaMoury, Sun Lee, Savvas Raptis, David Sibeck, Hui Zhang, Yufei Hao, Marcos Silveira, Boyi Wang, and Minna Palmroth

Solar wind directional discontinuities can generate transient mesoscale structures upstream of Earth's bow shock, which can have a global impact on the near-Earth environment. Understanding the formation conditions of these transient structures is crucial to evaluate their contribution to solar wind-magnetosphere coupling. Hot flow anomalies (HFAs) are thought to be created only by tangential discontinuities, and develop where the discontinuities intersect the shock. Foreshock bubbles, on the other hand, are associated with both tangential and rotational discontinuities, and are generated before the discontinuities reach the bow shock, as they form due to foreshock suprathermal ions accumulation on the upstream side of the discontinuities. Here we present the results of a global 2D hybrid-Vlasov simulation of the interaction of a rotational discontinuity with near-Earth space performed with the Vlasiator model. As the discontinuity enters the simulation domain, a foreshock bubble forms duskward of the Sun-Earth line, where the foreshock is initially located. Shortly after the discontinuity makes first contact with the bow shock at the subsolar point, we find that a structure with enhanced temperature and strongly deflected flows develops at the intersection of the discontinuity with the bow shock. This structure displays typical features of an HFA. This suggests that both a foreshock bubble and an HFA can be generated concurrently by a single directional discontinuity, and that a rotational discontinuity can lead to HFA formation in some conditions. We compare the ion distribution functions inside the foreshock bubble and the HFA, and find significant solar wind core heating within the HFA, as expected from spacecraft observations. We discuss how the properties of the structures vary spatially and temporally, providing global context to localised spacecraft measurements.

How to cite: Turc, L., Archer, M., Zhou, H., Kajdic, P., Blanco-Cano, X., Pfau-Kempf, Y., Liu, T., Lin, Y., Omidi, N., LaMoury, A., Lee, S., Raptis, S., Sibeck, D., Zhang, H., Hao, Y., Silveira, M., Wang, B., and Palmroth, M.: A rotational discontinuity can generate both a foreshock bubble and a hot flow anomaly, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20429, https://doi.org/10.5194/egusphere-egu24-20429, 2024.

EGU24-240 | ECS | Orals | ST1.12

Exploring CME - Solar Wind Interaction in Heliosphere using SWASTi framework 

Prateek Mayank, Bhargav Vaidya, Wageesh Mishra, and Dibyendu Chakrabarty

Coronal Mass Ejections (CMEs) are key to solar eruptions and geomagnetic storms, heavily influenced by their interaction with solar wind streams. Accurately predicting CME trajectories and impacts hinges on understanding how they evolve within ambient solar wind. Despite numerous qualitative studies, a detailed quantitative analysis of these interactions, crucial for predicting CME behavior, remains elusive, primarily due to the challenges in isolating CMEs from the solar wind.

In the initial segment of the presentation, I'll introduce a newly developed MHD model, SWASTi, offering fresh insights into CME-SW interaction through simulation. Developed on the PLUTO code framework, SWASTi integrates a modified WSA relation for setting initial solar wind conditions and features two CME modules: a basic non-magnetized cone CME and an advanced flux rope CME. I'll also discuss a passive scalar tracing approach, developed for isolating CME structures in the heliosphere and analyzing their interactions with stream interaction regions.

Following this, I'll delve into an in-depth analysis of CME interactions with variable ambient solar wind and the resulting effects on their evolution. Our approach involves two distinct setups: the 'real case', utilizing the standard SWASTi-CME flux rope model, and the 'synthetic case', a controlled scenario with uniform solar wind speed to examine CME behavior without SIR interference. The synthetic case, acting as a benchmark, allows us to measure the impact of solar wind variability on CME characteristics, contrasting it with findings from the real case.

To conclude, the presentation will highlight our research's key outcomes, encompassing both qualitative and quantitative dimensions. These include examining the deformation of the CME front, and the evolution of thermal, kinetic, and magnetic pressures. Additionally, I will discuss the dynamic nature and implications of the drag force exerted on CMEs. We observed that the volume of CME follows a non-fractal power-law expansion over time, eventually reaching a balanced state.

How to cite: Mayank, P., Vaidya, B., Mishra, W., and Chakrabarty, D.: Exploring CME - Solar Wind Interaction in Heliosphere using SWASTi framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-240, https://doi.org/10.5194/egusphere-egu24-240, 2024.

EGU24-1718 | ECS | Posters on site | ST1.12

An Algorithm For Determination of CME Kinematic Parameters Based On Machine Learning 

Rongpei Lin, Yi Yang, Fang Shen, Gibert Pi, and Yucong Li

Coronal Mass Ejections (CMEs) are the major source of space weather events, causing severe disturbance to Sun-Earth space environment. Since there are more and more space activities and facilities, it’s becoming increasingly significant to detect and track CMEs. We develop a new algorithm to automatically detect CMEs and derive CME’s kinematic parameters based on machine learning. Our method consists of three steps: Recognition, tracking and determination of parameters. First, we train a convolutional neural network (CNN) to classify images from SOHO LASCO coronagraph observation into two categories that contains CME(s) or not. Next, we apply Principal Component Analysis (PCA) algorithm and Otsu’s method to acquire binary-labelled CME regions. Then, we employ the track-match algorithm to track CME motion in time-series image sequence and finally determine CME kinematic parameters e.g., velocity, angular width (AW), and central position angle (CPA). The algorithm is validated on several CME events with different morphological characteristics. We compare the results with a manual CME catalog and automatic CME catalogs (including Computer Aided CME Tracking (CACTus), Solar Eruptive Event Detection System (SEEDS), CORonal Image Process method (CORIMP)). Our algorithm shows some advantages in the recognition of CME structure and the accuracy of the kinematic parameters. In the future, the algorithm is capable of being applied to initialize magnetohydrodynamic simulations to study the propagation characteristics of real CME events in the interplanetary space, and provide a more efficient prediction of CMEs' geo-effectiveness.

How to cite: Lin, R., Yang, Y., Shen, F., Pi, G., and Li, Y.: An Algorithm For Determination of CME Kinematic Parameters Based On Machine Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1718, https://doi.org/10.5194/egusphere-egu24-1718, 2024.

High-resolution EUV spectroscopy of the corona provides the most informative diagnostic tool for the early evolution of coronal mass ejections (CMEs) since it can directly measure many physical properties of CME plasma close to the Sun, which cannot be determined from coronagraphs and full-disk imagers. Hinode/EIS captured its full range of high-resolution EUV spectra of the April 9th, 2008 event, also known as the Cartwheel CME, during its initial acceleration period. Unique to this work, simulations of the Cartwheel CME with the Alfven Wave Solar atmosphere Model (AWSoM) and the Gibson-Low flux rope model, were performed to provide insight into the plasma structure and dynamics during the early evolution of this CME. We combined self-consistent non-equilibrium charge state calculations in the EUV spectral line synthesis for the first time, to account for the plasma departures from ionization equilibrium everywhere in the CME. Overall, the model is able to reproduce the dynamics of the CME, including the eruption of cold, dense prominence material. We discuss the thermodynamic evolution of CME’s plasma structure in the low solar corona, with particular attention given to the cold prominence material, and how the non-equilibrium charge states and EUV spectra evolve.

How to cite: Wraback, E., Landi, E., Manchester, W., and Szente, J.: The Cartwheel CME’s Evolution in the Low Solar Corona Simulated with Non-Equilibrium Charge States and Spectra for Comparison to High-Resolution EUV Spectroscopic Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1893, https://doi.org/10.5194/egusphere-egu24-1893, 2024.

EGU24-2230 | ECS | Posters on site | ST1.12

CME Transit Time Prediction Based on Coronagraph Observations and Machine Learning Techniques 

Yucong Li, Yi Yang, Fang Shen, and Rongpei Lin

A coronal mass ejection (CME) is a significant release of plasma and accompanying magnetic field from the solar corona, and is one important source of severe space weather events. With the accumulation of CME observations by coronagraphs and the excellent performance of convolutional neural network (CNN) in image classification, fast and accurate prediction of the transit (arrival) time of CMEs became possible. In this study, we present a new prediction method utilizing both a deep learning framework and the physical characteristic of CMEs based on remote-sensing observations. In total, the initial and arrival data of 168 geo-effective CME events from 2000-2020 are collected for the study. A convolutional neural network model is trained with the coronagraph images of the events observed by SOHO/LASCO. The output of the trained CNN is further combined with the initial CME speed to carry out a linear fitting process. The comparison with the prediction results merely based on a CNN or a linear fitting by CME speed indicates that the hybrid model can improve the accuracy of CME arrival time prediction.

How to cite: Li, Y., Yang, Y., Shen, F., and Lin, R.: CME Transit Time Prediction Based on Coronagraph Observations and Machine Learning Techniques, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2230, https://doi.org/10.5194/egusphere-egu24-2230, 2024.

EGU24-2651 | Posters on site | ST1.12

Solar Eruptions Triggered by Flux Emergence Below or Near a Coronal Flux Rope 

Tibor Torok, Mark G. Linton, James E. Leake, Zoran Mikic, Roberto Lionello, Viacheslav S. Titov, and Cooper Downs

Observations have shown a clear association of filament/prominence eruptions with the emergence of magnetic flux in or near filament channels. Magnetohydrodynamic (MHD) simulations have been employed to systematically study the conditions under which such eruptions occur. These simulations to date have modeled filament channels as two-dimensional (2D) flux ropes or 3D uniformly sheared arcades. Here we present MHD simulations of flux emergence into a more realistic configuration consisting of a bipolar active region containing a line-tied 3D flux rope. We use the coronal flux-rope model of Titov et al. (2014) as the initial condition and drive our simulations by imposing boundary conditions extracted from a flux-emergence simulation by Leake et al. (2013). We identify three mechanisms that determine the evolution of the system: (i) reconnection displacing foot points of field lines overlying the coronal flux rope, (ii) changes of the ambient field due to the intrusion of new flux at the boundary, and (iii) interaction of the (axial) electric currents in the pre-existing and newly emerging flux systems. The relative contributions and effects of these mechanisms depend on the properties of the pre-existing and emerging flux systems. Here we focus on the location and orientation of the emerging flux relative to the coronal flux rope. Varying these parameters, we investigate under which conditions an eruption of the latter is triggered.

How to cite: Torok, T., Linton, M. G., Leake, J. E., Mikic, Z., Lionello, R., Titov, V. S., and Downs, C.: Solar Eruptions Triggered by Flux Emergence Below or Near a Coronal Flux Rope, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2651, https://doi.org/10.5194/egusphere-egu24-2651, 2024.

EGU24-3405 | Posters on site | ST1.12

A pseudo-streamer unveiled by a jet and its interaction with a CME 

Brigitte Schmieder, Jinhan Guo, Pooja Devi, Ramesh Chandra, Yang Guo, and Stefaan Poedts

 

We revisit the observations of filament eruption,   extreme-ultraviolet (EUV) wave,  and  CME which originated from the active region (AR) NOAA 12887 on 28 October 2021. We analyze  a jet which initiated close to the flare loop footpoints, and its impact on neighboring loops. The event was observed by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) satellite at various wavebands and by the Solar TErrestrialRElations Observatory-Ahead (STEREO-A) with its Extreme-Ultraviolet Imager( EUVI) and COR1 instruments with a different view angle from SDO.

We show that the EUV-wave event consists of several waves as well as non-wave phenomena. The wave componentsinclude: the fast-mode part of the EUV wave event, creation of oscillations in nearby loops, and the appearance of wave trains. The non wave component consists of stationary fronts. We analyze selected oscillating loops and find that the periods of these oscillations range from 230 – 549 s. 

On the other hand the jet material lights loops which form a 3D null point. We evidence the existence of a  pseudo-streamer and its relationship with the CME (flux rope).

Our numerical MHD simulations with high resolution evidence  the existence of a pseudo-streamer, and its relationship with the CME (flux rope). We   catch the dynamic reconnection process between the flux rope and the pseudo-streamer and discuss the validity of our method compared to static methods.

How to cite: Schmieder, B., Guo, J., Devi, P., Chandra, R., Guo, Y., and Poedts, S.: A pseudo-streamer unveiled by a jet and its interaction with a CME, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3405, https://doi.org/10.5194/egusphere-egu24-3405, 2024.

EGU24-4425 | Posters on site | ST1.12

Sun-to-Earth CME Modeling with Data Assimilation and Uncertainty Quantification 

Gabor Toth, Yang Chen, Xun Huan, Bart van der Holst, Aniket Jivani, Hongfan Chen, Nishtha Sachdeva, Zhenguang Huang, and Ward Manchester

Supported by the Space Weather with Quantified Uncertainty (SWQU) NSF program, we have been developing the Next Generation Space Weather Modeling Framework at the University of Michigan for three years. The main goal of the project is to provide useful probabilistic forecast of major space weather events about 24 hours before the geospace impact occurs. We are using the first-principles models in the Space Weather Modeling Framework (SWMF) in combination with uncertainty quantification and data assimilation. Using the advanced MaxPro experimental design and fully automated Python scripts, we have performed thousands of solar wind background and coronal mass ejection (CME) simulations with the solar corona, inner heliosphere and eruptive event generator based on the Gibson-Low fluxrope (EEGGL) models of the SWMF. Our CME initiation model is at the surface of the Sun, so the CME can interact with the background solar wind and the magnetic field of the erupting active region. Based on these simulations, we have performed the uncertainty quantification analysis using the Bayesian inversion formula and a newly defined distance metric adapted to solar simulations. One important finding is that the physically meaningful range of the background solar wind model parameters depends on the solar cycle. We have identified the three most important parameters that impact the background solar wind model and two more parameters (the strength and helicity of the magnetic field of the fluxrope) that impact the CME eruption model. The reduced dimensionality of the parameter space enables reducing the size of the ensemble. Data assimilation provides further opportunity to improve the predictions. We are using in-situ observations at L1 prior to the CME to constrain the background solar wind and coronal white-light image observations right after the eruption to find the optimal flux rope parameters. We find that the CME arrival time error is significantly reduced to less than 5 hours by the data assimilation based on three events. Using an ensemble of simulations also provides a likely range for the various quantities of interest, including arrival time, solar wind speed and density and the BZ component of the magnetic field. The main product of the project, the Michigan Sun-to-Earth Model with Quantified Uncertainty and Data Assimilation (MSTEM-QUDA) is available as an open-source distribution at https://github.com/MSTEM-QUDA

How to cite: Toth, G., Chen, Y., Huan, X., van der Holst, B., Jivani, A., Chen, H., Sachdeva, N., Huang, Z., and Manchester, W.: Sun-to-Earth CME Modeling with Data Assimilation and Uncertainty Quantification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4425, https://doi.org/10.5194/egusphere-egu24-4425, 2024.

EGU24-4457 | Posters on site | ST1.12 | Highlight

CLEAR – All-Clear SEP Forecast: A NASA Space Weather Center of Excellence 

Lulu Zhao and Tamas Gombosi and the CLEAR Team

CLEAR will deliver capabilities for robust and quantifiable forecasts of the space radiation level of up to 24 hours, in support of aviation, satellites, and space exploration. Solar energetic particles (SEPs) can be accelerated over a wide range of energies extending up to GeVs. At relatively low energies (e.g., ~10 MeV), their flux intensity can exceed the background of galactic cosmic rays by several orders of magnitude. Protons of >100 MeV with elevated fluxes exceeding 1 proton flux unit are responsible for an increased astronaut exposure inside spacecraft shielding. Protons of >150MeV are very difficult to shield against as they can penetrate 20 gm cm (7.4 cm of Al, or 15.5 cm of water/human tissue). Furthermore, > 500 MeV protons can penetrate the atmosphere and pose radiation hazards to aviation. Besides protons, energetic heavy ions, e.g., Fe ions, can be of more severe radiation concerns. SEPs are hazardous not only to humans but also to electronics and other sensitive components in space, affecting satellite operations. The sparsity and high variability in terms of intensity, duration, composition,and energy spectra of SEP events make them difficult to predict. The CLEAR Center will develop, test and validate a self-contained, modular (“plug and play”) framework that includes all major elements impacting SEPs in the inner heliosphere: 4π maps of photospheric magnetic fields, corona (1 − 20Rs), inner and middle heliosphere (0.1 AU to Jupiter’s orbit) plasma environment, magnetic connectivity with respect to the solar source, flare/CME initiation, SEP seed population, flare and shock acceleration, and energetic particle transport. In addition, the framework will be able to accommodate radiation interaction models, which will be used to study the penetration of spacecraft walls, radiation effects on the terrestrial magnetosphere, and the radiation doses received by human tissues.

How to cite: Zhao, L. and Gombosi, T. and the CLEAR Team: CLEAR – All-Clear SEP Forecast: A NASA Space Weather Center of Excellence, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4457, https://doi.org/10.5194/egusphere-egu24-4457, 2024.

EGU24-5664 | ECS | Orals | ST1.12

Sun-as-a-star Spectroscopic Observations of the Line-of-sight Velocities of Solar Eruptions 

Yu Xu, Hongpeng Lu, and Hui Tian

The propagation direction and true velocity of a solar coronal mass ejection, which are among the most decisive factors for its geo-effectiveness, are difficult to determine through single-perspective imaging observations. Here we show that Sun-as-a-star spectroscopic observations, together with imaging observations, could allow us to solve this problem. Using observations of the Extreme Ultraviolet Variability Experiment (EVE) onboard the Solar Dynamics Observatory (SDO), we found clear blueshifted secondary emission components in extreme-ultraviolet spectral lines during a solar eruption on 2021 October 28. From simultaneous imaging observations, we found that the secondary components are caused by a mass ejection from the flare site. We estimated the line-of-sight (LOS) velocity of the ejecta from both the double Gaussian fitting method and the red-blue asymmetry analysis. The results of both methods agree well with each other, giving an average LOS velocity of the plasma of ∼423 km s−1. From the 304 Å image series taken by the Extreme ultraviolet Imager onboard the Solar Terrestrial Relation Observatory-A (STEREO-A) spacecraft, we estimated the plane-of-sky velocity from the STEREO-A viewpoint to be around 587 km s−1. The full velocity of the bulk motion of the ejecta was then computed by combining the imaging and spectroscopic observations, which turns out to be around 596 km s−1 with an angle of 42.4 degrees to the west of the Sun–Earth line and 16.0 degrees south to the ecliptic plane.

Similar technics were applied to other eight events after systematically searching Sun-as-a-star spectra observed by the EVE/SDO from 2010 May to 2022 May. We identified eight CMEs associated with flares and filament eruptions by analyzing the blue-wing asymmetry of the O III 52.58 nm line profiles and estimated their full velocivites as well as propagation directions. We find a strong correlation between geomagnetic indices (Kp and Dst) and the angle between the CME propagation direction and the Sun–Earth line, suggesting that Sun-as-a-star spectroscopic observations at extreme-ultraviolet wavelengths can potentially help to improve the prediction accuracy of the geoeffectiveness of CMEs. Moreover, an analysis of synthesized long-exposure Sun-as-a-star spectra implies that it is possible to detect CMEs from other stars through blue-wing asymmetries or blueshifts of spectral lines.

How to cite: Xu, Y., Lu, H., and Tian, H.: Sun-as-a-star Spectroscopic Observations of the Line-of-sight Velocities of Solar Eruptions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5664, https://doi.org/10.5194/egusphere-egu24-5664, 2024.

EGU24-5702 | ECS | Posters on site | ST1.12

Deriving the interaction point of an Interplanetary Coronal Mass Ejection and High-Speed stream : A case study 

Akshay Kumar Remeshan, Mateja Dumbović, and Manuela Temmer

Understanding the propagation and evolution of Coronal Mass Ejections (CMEs) is one of the fundamental problems in Heliospheric Physics. An important factor in comprehending the evolution of CMEs in interplanetary space (ICMEs) is studying the different interactions they undergo, such as with high-speed streams (HSS) originating from coronal holes (CH). We study the interaction of an ICME detected in situ at the L1 Lagrange point on 12th October 2016 with a trailing HSS. The in-situ measurements indicate a Magnetic Obstacle (MO) with a symmetric flux rope structure and reconnection exhaust signatures at the ICME-HSS boundary. The ICME is associated with a Halo CME recorded in the LASCO CME catalogue on 9th October 2016. We use Graduated Cylindrical Shell (GCS) reconstruction to obtain 3D CME characteristics and SDO AIA 193 Å measurements to analyse basic CH properties. We next use "a two-step Drag Based Model (DBM)" together with EUropean Heliospheric FORecasting Information Asset (EUHFORIA) to model and analyse the interaction and estimate where in the heliosphere the interaction takes place. We find that the results from the two-step DBM model give better justification for the observed in-situ signatures compared to the EUHFORIA run; this could be due to the lack of reliable magnetogram data from the backside of the Sun. Our analysis indicates that the interaction between ICME and HSS initiated relatively close to Earth (~0.9 AU), providing a benchmark to study ICME-HSS interaction at an early phase.

How to cite: Remeshan, A. K., Dumbović, M., and Temmer, M.: Deriving the interaction point of an Interplanetary Coronal Mass Ejection and High-Speed stream : A case study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5702, https://doi.org/10.5194/egusphere-egu24-5702, 2024.

EGU24-6047 | ECS | Orals | ST1.12

Probing CME’s inclination effects with EUHFORIA 

Karmen Martinić, Eleanna Asvestari, Mateja Dumbović, Manuela Temmer, and Bojan Vršnak

The dynamics of coronal mass ejections (CMEs) in interplanetary space (IPS) are primarily determined by the interaction of the CME with the interplanetary magnetic field (IMF) and the surrounding solar wind (SW). CMEs are complex magnetized plasma structures in which the magnetic field spirals around a central axis, forming what is known as a flux rope (FR). This FR axis can be oriented at any angle with respect to the ecliptic. Throughout its journey, a CME will encounter  IMF and SW in IPS which is neither homogeneous nor isotropic. Consequently, CMEs with different orientations will encounter different ambient medium conditions. It is thus expected that the interaction of the CME with its surrounding environment will vary depending on the orientation of its FR axis, among other factors. This study aims to fill the gap in the understanding of the effect of inclination on CME propagation in the heliosphere. This is achieved by performing simulations with the EUropean Heliospheric FORecasting Information Asset (EUHFORIA) 3D magnetohydrodynamic (MHD) model. This study focuses on two CMEs with nearly identical properties, differing only by their inclination, which are simulated using the spheromak CME implementation in the model. We show the effects of CME orientation on sheath evolution, MHD drag, and non-radial flows in radial, longitudinal, and latitudinal directions, by analyzing the model data from a swarm of 81 virtual spacecrafts scattered across the inner heliospheric domain of EUHFORIA. These results provide new insights into CME dynamics, the understanding of which is critical for improving space weather forecasting.

How to cite: Martinić, K., Asvestari, E., Dumbović, M., Temmer, M., and Vršnak, B.: Probing CME’s inclination effects with EUHFORIA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6047, https://doi.org/10.5194/egusphere-egu24-6047, 2024.

EGU24-8128 | Posters virtual | ST1.12

First Determination in the Extended Corona of the 2D Thermal Evolution of a Current Sheet after a Solar Eruption 

Alessandro Bemporad, Guanglu Shi, Shuting Li, Beili Ying, Li Feng, and Jun Lin and the Metis Team

For the first time the evolution of the coronal reconfiguration after a Coronal Mass Ejection (CME) was observed by the multi-channel Metis Coronagraph on-board the ESA - Solar Orbiter mission. The images acquired in the Visible Light (VL) between 3.0 and 5.4 Rsun show the formation after a CME of a bright elongated radial feature interpreted as a post-CME Current Sheet (CS). This interpretation is supported by the appearance of the same feature as an intensity decrease in the UV Lyman-alpha images. The unique combination of VL and UV images allowed for the first time to map in 2D the time evolution of multiple plasma physical parameters inside and outside the CS region. In particular, the CS electron temperature reached peak values higher than 1 MK, more than 2 times larger than the surrounding corona in the covered altitude range. An elongated vertical diffusion region (DR), characterized as a region of much higher thermal pressure and lower magnetic pressure, is observed to slowly propagate outward during 13 hours of observations. Inside this region the Alfvènic Mach number is on the order of MA ≃ 0.02 - 0.11, the plasma β is close to unity, and the level of turbulence is higher than the surrounding corona, but decreases slowly with time. All these results provide one of the most complete pictures of these features, and support the idea of a magnetic reconnection coupled with turbulence and occurring in multiple smaller scale CSs resulting in the much broader macroscopic feature observed with the Metis coronagraph. This allows magnetic reconnection to provide a significant heating of the local plasma, despite the weakness of involved coronal magnetic fields in the considered altitude range.

How to cite: Bemporad, A., Shi, G., Li, S., Ying, B., Feng, L., and Lin, J. and the Metis Team: First Determination in the Extended Corona of the 2D Thermal Evolution of a Current Sheet after a Solar Eruption, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8128, https://doi.org/10.5194/egusphere-egu24-8128, 2024.

EGU24-8257 | ECS | Orals | ST1.12

Identifying and Tracking Solar Flux Ropes in Simulation Data and Deflection Analysis of AR11176 and AR12473 Flux Ropes 

Andreas Wagner, Slava Bourgeois, Emilia Kilpua, Ranadeep Sarkar, Daniel Price, Anshu Kumari, Jens Pomoell, Stefaan Poedts, Teresa Barata, Robertus Erdélyi, Orlando Oliveira, and Ricardo Gafeira

To improve our understanding of how space weather affects our near-Earth space environment, magnetic field modelling of solar eruptive structures is essential. In particular, modelling flux ropes in a time-dependent manner to investigate their destabilization in the low corona as well as their morphological evolution and propagation can yield important information about the eruption's impact at Earth. However, finding and tracking the magnetic field lines that pertain to the flux rope in simulation data is a non-trivial task. Therefore, we developed a methodology to extract and track flux ropes in a semi-automatic way, using a combination of some flux rope proxies (like the twist parameter) and mathematical morphology algorithms. This procedure is also wrapped into a graphical user interface (GUI) to increase the user-friendliness of the methodology. We subsequently apply this methodology to time-dependent magnetofrictional method (TMFM) simulations of active regions AR12473 and AR11176. For the former, we chose to simulate a time window which featured an eruption, while for the latter, we model the active region at a time where there was only mild activity. We then analyse the propagation of the flux ropes through the low corona. We find that the eruptive flux rope of AR12473 clearly shows significant changes in the propagation direction with deflection angles peaking at 60 degrees. The AR11176 flux rope appears to be more stable, but still features non-negligible deflections peaking at about 40 degrees.

How to cite: Wagner, A., Bourgeois, S., Kilpua, E., Sarkar, R., Price, D., Kumari, A., Pomoell, J., Poedts, S., Barata, T., Erdélyi, R., Oliveira, O., and Gafeira, R.: Identifying and Tracking Solar Flux Ropes in Simulation Data and Deflection Analysis of AR11176 and AR12473 Flux Ropes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8257, https://doi.org/10.5194/egusphere-egu24-8257, 2024.

EGU24-8788 | Posters on site | ST1.12

CME-CME-CIR interaction - comparison of "homologous" events from two different solar rotations  

Manuela Temmer, Mateja Dumbovic, Karmen Martinic, Greta M. Cappello, Akshay K. Remeshan, Daniel Milosic, Florian Koller, Jasa Calogovic, and Filip Matkovic

Solar cycle 25 might be close to its expected peak and related activity is at a high. In 2023 many complex events were observed remotely and measured in-situ. Some of them even caused aurorae in low latitudes, repeatedly confirming that the interaction between multiple CMEs, as well as CIRs, lead to extreme conditions in near-Earth space. We study a set of “homologous” events on the Sun, where several CMEs interacted and additionally interfered by a high-speed stream from a coronal hole. The two sets of events involve the same active regions and coronal hole but are separated by a full solar rotation. We point out the complexity for each set of events and aim to understand how the global magnetic field configuration leads to a general similarity in the activation of the CME source regions. The studied in-situ measurements are connected to the solar surface observations and interpreted by processes caused due to shock-magnetic obstacle interaction.

How to cite: Temmer, M., Dumbovic, M., Martinic, K., Cappello, G. M., Remeshan, A. K., Milosic, D., Koller, F., Calogovic, J., and Matkovic, F.: CME-CME-CIR interaction - comparison of "homologous" events from two different solar rotations , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8788, https://doi.org/10.5194/egusphere-egu24-8788, 2024.

EGU24-8864 | ECS | Orals | ST1.12

On quantifying the impact of CME magnetic flux and mass erosion on geo-effectiveness  

Anwesha Maharana, Sergio Dasso, Sanchita Pal, Eleanna Asvestari, Luciano Rodriguez, Jasmina Magdalenic, Camilla Scolini, and Stefaan Poedts

Coronal mass ejections (CMEs) undergo erosion, deflection, and deformation upon interaction with the solar wind structures and with other transients during their propagation in the solar corona and heliosphere. In this work, we focus on the process of the erosion of CMEs in the heliosphere, which impacts their magnetic flux content, and its effect on altering their geo-effectiveness. To quantify the erosion of CME magnetic flux and mass in various solar wind environments, we employ 3D magnetohydrodynamic (MHD) simulations. 

To create a simulated solar wind background resembling a solar minimum period (for simplistic cases), we utilize the EUropean Heliosphere FORecasting Information Asset (EUHFORIA, Pomoell and Poedts, 2018) model. Through this background, we evolved a CME from 0.1 au to 2 au using a linear force-free spheromak model. We employ two distinct methods to assess erosion of magnetic flux and mass. 

First, the in-situ method, where the single point data at Earth or any other location is used to quantify the magnetic flux erosion. The orientation of the CME in the magnetic cloud frame of reference is determined through minimum variance analysis, and the accumulated axial and azimuthal flux is computed (Dasso et al, 2006). Imbalances in the flux profile serve as indicators of erosion. 

The second method relies on 3D simulation data, tracking the mass of the magnetic cloud in three dimensions based on criteria developed by Asvestari et al, 2022 for the spheromak model. With this method we can identify the 3D volume of the spheromak, assess its orientation, rotation, and magnetic properties in 3D in the local frame of reference of the spheromak structure. This technique provides us with the magnetic flux content of the spheromak and how it changes in space and time. 

Following a benchmarking process between the two erosion quantification methods, we conduct simulations to explore the sensitivity of CME erosion to variations in geometrical and magnetic field parameters. The study also investigates the influence of interactions with high-speed streams on erosion. Lastly, we apply an empirical Dst model (O’Brien and McPherron, 2000) to quantify geo-effectiveness and establish correlations with estimated erosion in all cases.

How to cite: Maharana, A., Dasso, S., Pal, S., Asvestari, E., Rodriguez, L., Magdalenic, J., Scolini, C., and Poedts, S.: On quantifying the impact of CME magnetic flux and mass erosion on geo-effectiveness , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8864, https://doi.org/10.5194/egusphere-egu24-8864, 2024.

EGU24-9858 | ECS | Posters on site | ST1.12

Investigating the coherency and expansion of ICMEs using multi-spacecraft observations 

Emma Davies, Christian Möstl, Eva Weiler, and Robert Forsyth

Studies of ICMEs observed by multi-spacecraft over varying longitudinal and radial separations provide valuable insight into the general properties, expansion, and possible interaction with other features of the solar wind environment as the ICME propagates. Previous studies have suggested that ICMEs are not coherent structures, but may display locally apparent coherence due to similar initial conditions and quasi homogeneity of the solar wind background through which they propagate.

In this study, we use a tool to match distinct features observed in the magnetic field profiles measured at each spacecraft as a proxy for coherence, and investigate the types of ICME and scales over which this is possible using those listed in the HELIO4CAST lineup catalogue v2.0 (https://helioforecast.space/lineups). In addition, we use the timing and positions of these matched features to calculate the mean propagation velocities of these features between the spacecraft. We present example CME events comparing the calculated mean propagation velocity profiles to those measured in situ where plasma data is available, and investigate the relationship between local and global expansion.

How to cite: Davies, E., Möstl, C., Weiler, E., and Forsyth, R.: Investigating the coherency and expansion of ICMEs using multi-spacecraft observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9858, https://doi.org/10.5194/egusphere-egu24-9858, 2024.

EGU24-10017 | Posters on site | ST1.12

Evolution of sheaths and magnetic obstacle from the inner to the outer heliosphere.  

Carlos Larrodera and Manuela Temmer

Our study covers a comprehensive analysis of Interplanetary Coronal Mass Ejections (ICMEs) across a wide distance from 0.25-5.42 AU and temporal range from 1975-2022. Our primary focus is a statistical examination of a variety of physical parameters for the structures within ICMEs, specifically the sheath and magnetic obstacle (MO). Our methodological approach integrates data merging from 13 individual ICME catalogs into a unified catalog, facilitating a comprehensive evaluation of in-situ measurements obtained from diverse spacecraft. This approach offers an opportunity to discern variances across different solar cycles. Our empirical findings provide intriguing insights. Notably, MOs preceded by a sheath exhibit a marked increase in size upon reaching 1 AU from the Sun. Furthermore, both structures, MO and sheath, experience a strong increase in size around 0.75 AU, correlating with a decrease in the measured density at this distance. Moreover, our analysis reveals a shift in the spatial positioning of material accumulation proximate to the sheath interface. This transformation suggests a potential transition in the underlying mechanism governing sheath formation, indicating a shift from externally driven to internally accumulated material processes.

How to cite: Larrodera, C. and Temmer, M.: Evolution of sheaths and magnetic obstacle from the inner to the outer heliosphere. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10017, https://doi.org/10.5194/egusphere-egu24-10017, 2024.

EGU24-12577 | Orals | ST1.12

New Insights on the Interiors of Coronal Mass Ejections from the WISPR and SoloHI Heliospheric Imagers 

Phillip Hess, Robin Colaninno, Angelos Vourlidas, Russell Howard, Guillermo Stenborg, and Shaheda Shaik

Much of our current understanding of the internal structure of coronal mass ejections (CMEs) has been based on either high-resolution, multi-wavelength imaging near the Sun or in-situ crossings of a CME, typically near 1 au. Previous remote sensing instruments, observing the corona and heliosphere from close to 1 au, were able to observe CMEs in Thomson scattered white light but were limited in detail that could be resolved by the constraints imposed by observing from such a large distance. As a result, a thorough understanding of the bulk shape and leading-edge propagation in the heliosphere has been developed, but many open questions about the interior of a CME as well as its overall impact on the corona still remain open. Heliospheric Imager data from the Wide Field Imager for Solar Probe (WISPR) on board the Parker Solar Probe and the Solar Orbiter Heliospheric Imager (SoloHI) on board Solar Orbiter have provided new high-resolution imaging by observing from within the inner heliosphere and corona.  The unprecedented resolution of these observations allows us to directly address these key physical questions relating to the internal structure, coherency and evolution of coronal mass ejections as they propagate away from the Sun. Utilizing data from both of these instruments, we will show examples of the complex interior structures present in the images and explain the physical implications of these observations.

How to cite: Hess, P., Colaninno, R., Vourlidas, A., Howard, R., Stenborg, G., and Shaik, S.: New Insights on the Interiors of Coronal Mass Ejections from the WISPR and SoloHI Heliospheric Imagers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12577, https://doi.org/10.5194/egusphere-egu24-12577, 2024.

EGU24-13471 | Orals | ST1.12

Coronal Magnetic Eruptions: Observations, Models, and Techniques  

Nada Al-Haddad, Mitchell Berger, Wenyuan Yu, Florian Regnault, Noé Lugaz, Charles Farrugia, and Bin Zhuang

Multi-spacecraft measurements of Coronal Mass Ejections (CMEs) have made advancements in understanding their complex magnetic configurations and structures in interplanetary space. Analysis techniques for single-spacecraft measurements were initially adapted, however, they fall short in fully leveraging the potential of multi-spacecraft data. Recent efforts have aimed to rectify this limitation by developing specialized analysis methods tailored explicitly for multi-spacecraft measurements. These advancements allow for a more comprehensive understanding of CMEs' structures, propagation, and aging.

Moreover, the existing models and theories used to interpret CME data often rely on assumptions that might oversimplify the complexities of these phenomena. To address this, newer models and numerical simulations are being developed to test and validate these assumptions, ensuring a more accurate representation of CME properties. In addition, mathematical tools capable of deriving the intricate topological properties inherent in CME structures in IP space need to be developed.

One crucial aspect highlighted in this presentation is the necessity for dedicated multi-spacecraft missions specifically designed to capture the variation scales of magnetic structures within CMEs. This emphasizes the importance of optimal spacecraft formations that can provide optimal measurements, that allows for a better understanding of the magnetic configuration and internal structures of CMEs.

How to cite: Al-Haddad, N., Berger, M., Yu, W., Regnault, F., Lugaz, N., Farrugia, C., and Zhuang, B.: Coronal Magnetic Eruptions: Observations, Models, and Techniques , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13471, https://doi.org/10.5194/egusphere-egu24-13471, 2024.

EGU24-13582 | Posters on site | ST1.12

Determining the CME Onset Mechanism  

Spiro Antiochos, Bart van der Holst, Tamas Gombosi, Igor Sokolov, Lulu Zhao, and Joel Dahlin

Coronal Mass Ejections (CME) are the drivers of the most destructive space weather at Earth; therefore, determining their onset mechanism is of paramount importance for both space physics understanding and space weather prediction.  Two types of models for CME onset have been proposed: an ideal instability as in the kink or torus models, or magnetic reconnection as in the breakout or tether-cutting models. These two types are distinguished by the nature of the pre-eruption filament channel that powers the CME, a twisted flux rope in the case of the ideal mechanisms and a sheared arcade in the case of reconnection.  We describe two powerful new capabilities within the Space Weather Modeling Framework (SWMF) that enable the simulation of either ideal or reconnection driven CMEs. For ideal onset, we have developed and implemented a finite-beta extension of the well-known Titov-Demoulin twisted flux rope model. We present simulations using this capability and describe its application to event studies. For reconnection-driven onset we have developed and implemented the STITCH formalism, which efficiently captures the buildup of magnetic shear along a polarity inversion line by the process of helicity condensation.  We present simulations using this capability, as well, and describe its application to event studies. Furthermore, we discuss how these capabilities within SWMF will enable the community to simulate well-observed events with both ideal and reconnection onset, and by detailed comparison with the observations, finally determine the CME onset mechanism.

This work was supported by the NSF SHINE Program and the NASA Living With a Star Program.

 

How to cite: Antiochos, S., van der Holst, B., Gombosi, T., Sokolov, I., Zhao, L., and Dahlin, J.: Determining the CME Onset Mechanism , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13582, https://doi.org/10.5194/egusphere-egu24-13582, 2024.

EGU24-14401 | ECS | Posters on site | ST1.12

Integration of a Novel Flux Rope Model into Global MHD Simulations for Analyzing the Space Weather Effects of Coronal Mass Ejections 

Ranadeep Sarkar, Jens Pomoell, Emilia Kilpua, and Eleanna Asvestari

One of the major challenges in space weather forecasting is to reliably predict the magnetic structure of interplanetary coronal mass ejections (ICMEs) in the near-Earth space. In the framework of global MHD modelling, several efforts have been made to model the CME magnetic field from Sun to Earth. However, it remains challenging to deduce a flux-rope solution that can reliably model the magnetic structure of a CME. Spheromaks are one of the models that are widely used to characterize the internal magnetic structure of a CME. However, recent studies show that spheromaks are prone to experience a large rotation when injected in the heliospheric domain which may affect the prediction efficacy of CME magnetic fields at 1 AU. Moreover, the fully inserted spheromaks do not have any legs attached to the Sun. In addition, due to the inherent topology of the spheromak, the in-situ signature may exhibit a double flux-rope-like profile not reproduced by standard locally cylindrical flux rope models. Aiming to study the dynamics of CMEs exhibiting different magnetic topologies, we implement a new flux-rope model in “European heliospheric forecasting information asset” (EUHFORIA). Our flux-rope model includes an initially force-free toroidal flux-rope that is embedded in the low-coronal magnetic field. The dynamics of the flux rope in the low and middle corona is solved by a non-uniform advection constrained by the observed kinematics of the event. This results in a global non-toroidal loop-like magnetic structure that locally manifests as a cylindrical structure. At heliospheric distances, the evolution is modeled as a MHD process using EUHFORIA. As proof of concept, we use this tool to two CME events. Comparing the model results with the in-situ magnetic field configuration of the ICME at 1 au, we find that the simulated magnetic field profiles of the flux-rope are in very good agreement with the in-situ observations. Therefore, the framework of toroidal model implementation as developed in this study could prove to be a major step-forward in forecasting the geo-effectiveness of CMEs.

How to cite: Sarkar, R., Pomoell, J., Kilpua, E., and Asvestari, E.: Integration of a Novel Flux Rope Model into Global MHD Simulations for Analyzing the Space Weather Effects of Coronal Mass Ejections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14401, https://doi.org/10.5194/egusphere-egu24-14401, 2024.

EGU24-15438 | ECS | Orals | ST1.12

The Next Era of CME Modeling at NASA's CCMC with CORHEL-CME 

Martin Reiss, Damian Barrous-Dume, Ronald Caplan, Cooper Downs, Matthew Lesko, Jon Linker, Peter MacNeice, Leila Mays, Maksym Petrenko, Andres Reyes, Viacheslav Titov, Tibor Török, and Tina Tsui

NASA's Community Coordinated Modeling Center (CCMC) presents CORHEL-CME, our newest addition to the Runs-On-Request system in the solar and heliospheric modeling domain. CORHEL-CME, developed by Predictive Science Inc., is a highly automated and interactive MHD modeling framework designed to simulate multiple coronal mass ejections within a realistic coronal and heliospheric environment. It combines three key innovations:

1. Interactive design of CMEs using a GUI-based web interface

CORHEL-CME's user interface is designed for non-experts. It offers real-time diagnostics to assist with model settings, guides users through creating full physics-based CME simulations, and provides web-based visualization reports.

2. Modeling CMEs originating from complex active regions

CORHEL-CME includes a flux rope model called RBSL (Titov et al., 2018), allowing users to create pre-eruptive flux rope configurations above elongated and curved polarity inversion lines. This feature enables users to realistically simulate CMEs originating from complex active regions.

3. Efficient, full physics-based simulations of CMEs

Using the web interface, the users set up simulation runs, including a simplified (zero-beta) MHD model of multiple flux ropes, a quasi-steady-state coronal MHD background model, and a high-fidelity time-dependent CME simulation. All simulation runs are performed on AWS high-performance GPU servers maintained by the CCMC.

In this presentation, we will showcase the usage of CORHEL-CME via CCMC's Runs-On-Request system and show an example run based on an event from March 7th, 2012. The new framework is publicly accessible through the CCMC website.

How to cite: Reiss, M., Barrous-Dume, D., Caplan, R., Downs, C., Lesko, M., Linker, J., MacNeice, P., Mays, L., Petrenko, M., Reyes, A., Titov, V., Török, T., and Tsui, T.: The Next Era of CME Modeling at NASA's CCMC with CORHEL-CME, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15438, https://doi.org/10.5194/egusphere-egu24-15438, 2024.

EGU24-17104 | ECS | Orals | ST1.12

Enhancing STEREO-HI data with machine learning for efficient CME forecasting 

Justin Le Louëdec, Maike Bauer, Tanja Amerstorfer, and Jackie A. Davies

Observing and forecasting Coronal Mass Ejections (CME) is crucial due to the potentially strong geomagnetic storms generated and their impact on satellites and electrical devices. With its near-real-time availability, STEREO-HI beacon data is the perfect candidate for efficient forecasting of CMEs. However, previous work concluded that prediction based on beacon data could not achieve the same accuracy as with high-resolution science data due to data gaps and lower quality. We have introduced a new method to improve the resolution and quality of near-real-time beacon data by using advanced machine-learning techniques while maintaining consistency between consecutive frames. This method also allows us to forecast intermediary and subsequent frames using a data-driven model for CME propagation within HI images. The output generated by our model produces smoother and more detailed time-elongation plots (J-plots) that are used as input for the Ellipse Evolution model based on Heliospheric Imager observations (ELEvoHl). We have compared the data produced by our model with the science data and analysed its impact on CME forecasting and propagation.

How to cite: Le Louëdec, J., Bauer, M., Amerstorfer, T., and Davies, J. A.: Enhancing STEREO-HI data with machine learning for efficient CME forecasting, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17104, https://doi.org/10.5194/egusphere-egu24-17104, 2024.

EGU24-388 | ECS | Orals | ST1.14

Solar rotation signatures in cosmic dust data measured by the Wind spacecraft 

Lennart Robin Baalmann, Arthur Péronne, Silvan Hunziker, Christoph Strähl, James W. Kirchner, Karl-Heinz Glaßmeier, Shivank Chadda, David M. Malaspina, Lynn B. Wilson III, and Veerle J. Sterken

Through serendipitous measurements with its plasma wave antennas, the Wind spacecraft recorded more than one hundred thousand impacts of cosmic dust particles onto the spacecraft body. Frequency analysis of the time series of impact data reveals signatures of the solar rotation.

These solar rotation signatures are transient in time. Case studies of time periods with particularly long-lasting corotating interaction regions (CIRs) yield stronger solar rotation signatures in the dust data than case studies of time periods with short-duration CIRs or few CIRs. This indicates that CIRs are a likely cause of the solar rotation signatures, possibly in combination with the alternating sector structure of the solar wind.

One physical mechanism that can cause the solar rotation signature, besides temporary changes of the spacecraft's floating potential that may influence the signal, is a local depletion of dust particles when a CIR passes by the spacecraft. A similar mechanism has been proposed to occur during coronal mass ejections (CMEs) and has been observed in close vicinity to the Sun with Parker Solar Probe. A statistical depletion analysis of the Wind cosmic dust impact data finds that both CMEs and CIRs with strong magnetic fields can locally deplete dust. This effect is strongest for small particles in CMEs.

How to cite: Baalmann, L. R., Péronne, A., Hunziker, S., Strähl, C., Kirchner, J. W., Glaßmeier, K.-H., Chadda, S., Malaspina, D. M., Wilson III, L. B., and Sterken, V. J.: Solar rotation signatures in cosmic dust data measured by the Wind spacecraft, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-388, https://doi.org/10.5194/egusphere-egu24-388, 2024.

EGU24-724 | ECS | Orals | ST1.14

Examination of Magnetic Helicity and Plasma Oscillation Periods in the Active Region NOAA12353 Prior to three C-Class Flares. 

Aneta Wisniewska, Marianna B. Korsos, Ioannis Kontogiannis, Szabolcs Soós, and Robertus Erdélyi

This work aims to investigate the long-period oscillations of NOAA12353 prior to a series of C-class flares and to correlate the findings with the 3-5 minute oscillations that were previously studied in the same active region. The objective of this work is to elucidate the presence of various oscillations with long periods in the lower solar atmosphere both before and after the flare events. Understanding the relationship between oscillations in solar active regions and their solar eruption activity is essential. To detect long-period oscillations the emergence, shearing, and total magnetic helicity flux components were assessed from the photosphere to the top of the chromosphere. To analyse the magnetic helicity flux in the lower solar atmosphere, linear force-free field extrapolation was used to construct a model of the magnetic field structure of the active region. Subsequently, the location of long-period oscillations in the active region was probed by examining the spectral energy density of the measured intensity signal in the 1700Å, 1600Å, and 304Å channels of the Atmospheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO). Significant periods of oscillations were determined by means of wavelet analysis. Based on the evolution of the three magnetic helicity flux components, 3-8 hour periods were found both before and after the flare events, spanning from the photosphere to the chromosphere. These 3-8 hour periods were also evident throughout the active region in the photosphere in the 1700Å channel. Observations of AIA 1600Å and 304Å channels, which cover the chromosphere to the transition region, revealed oscillations lasting 3-8 hours near the region where the flare occurred. The spatial distribution of the measured long-period oscillations mirror the previously reported distribution of 3-5 minute oscillations in NOAA12353, seen both before and after the flares. 
This case study suggest that varying oscillation properties in a solar active region could be indicative of future flaring activity.

How to cite: Wisniewska, A., Korsos, M. B., Kontogiannis, I., Soós, S., and Erdélyi, R.: Examination of Magnetic Helicity and Plasma Oscillation Periods in the Active Region NOAA12353 Prior to three C-Class Flares., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-724, https://doi.org/10.5194/egusphere-egu24-724, 2024.

EGU24-2063 | ECS | Orals | ST1.14

The Radial Distribution of Ion-scale Waves in the Inner Heliosphere 

Liu Wen and Zhao Jinsong
Determining the mechanism responsible for plasma heating and particle acceleration is a fundamental problem in
the study of the heliosphere. Due to effificient wave–particle interactions of ion-scale waves with charged particles,
these waves are widely believed to be a major contributor to ion energization, and their contribution considerably
depends on the wave occurrence rate. By analyzing the radial distribution of quasi-monochromatic ion-scale waves
observed by the Parker Solar Probe, this work shows that the wave occurrence rate is signifificantly enhanced in the
near-Sun solar wind, specififically 21%–29% below 0.3 au, in comparison to 6%–14% beyond 0.3 au. The radial
decrease of the wave occurrence rate is not only induced by the sampling effect of a single spacecraft detection, but
also by the physics relating to the wave excitation, such as the enhanced ion beam instability in the near-Sun solar
wind. This work also shows that the wave normal angle θ, the absolute value of ellipticity ò, the wave frequency f
normalized by the proton cyclotron frequency fcp, and the wave amplitude δB normalized by the local background
magnetic fifield B0 slightly vary with the radial distance. The median values of θ, ò, f, and δB are about 9°, 0.73,
3fcp, and 0.01B0, respectively. Furthermore, this study proposes that the wave mode natures of the observed left-
handed and right-handed polarized waves correspond to the Alfvén ion cyclotron mode wave and the fast
magnetosonic whistler mode wave, respectively.

How to cite: Wen, L. and Jinsong, Z.: The Radial Distribution of Ion-scale Waves in the Inner Heliosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2063, https://doi.org/10.5194/egusphere-egu24-2063, 2024.

EGU24-2482 | Orals | ST1.14 | Highlight

Suprathermal Ion Acceleration at the Near-Sun Heliospheric Current Sheet Crossings observed by Parker Solar Probe During Encounters 7-15 

Mihir Desai and the Parker Solar Probe, ISOIS, FIELDS, and SWEAP Science TE]tams

We report observations of time-intensity profiles, velocity dispersion, pitch-angle distributions, spectral forms, and maximum energies of <500 keV/nucleon suprathermal (ST) H, He, O, and Fe ions in association with eight separate crossings of the heliospheric current sheet (HCS) that occurred near perhelia during Parker Solar Probe (PSP) encounters E7-E15. We find that the ST ion observations fall into three categories, namely: 1) the E07 observations posed serious challenges for existing models of ST ion production in the inner heliosphere; 2) ST observations during 6 separate HCS crossings are consistent with a scenario in which the accelerated ions escape out of sunward-located reconnection exhausts; and 3) a near 4-hr HCS crossing during E14 when PSP traversed regions close to the reconnection exhaust and observed ST protons up to ~550 keV in energy. The reconnection exhaust or the source of these ST ions subsequently moved outside of PSP orbit thus resulting in a >10:1 sunward flow of the accelerated ST ions. We present detailed analysis of the evolution of the pitch-angle distributions and spectral properties during this crossing which have revealed, for the first time, important clues about the nature of ion acceleration via reconnection-driven mechanisms at the near-Sun HCS.

How to cite: Desai, M. and the Parker Solar Probe, ISOIS, FIELDS, and SWEAP Science TE]tams: Suprathermal Ion Acceleration at the Near-Sun Heliospheric Current Sheet Crossings observed by Parker Solar Probe During Encounters 7-15, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2482, https://doi.org/10.5194/egusphere-egu24-2482, 2024.

EGU24-2490 | ECS | Orals | ST1.14 | Highlight

Investigating the Complex Heliosheath of our Heliospheric Shield 

Marc Kornbleuth, Merav Opher, Erick Powell, Chika Onubogu, Xiaohan Ma, and John Richardson

The solar wind travels supersonically in the solar system until it reaches the termination shock, where it
is slowed down due to the interplay between the interstellar medium (ISM) and heliosphere. The region
of slowed down solar wind is referred to as the heliosheath, where a great number of mysteries remain
unsolved. Within the SHIELD NASA Drive Center, investigating the physical processes within the
heliosheath and their consequences is a fundamental goal in understanding both the shape of the
heliosphere and also how it protects the solar system from harmful galactic cosmic rays. Here, we
highlight some of the findings of SHIELD: (1) a Rayleigh-Taylor like instability develops in the
heliosheath due to charge exchange, which in turn allows for mixing between the solar wind and ISM
plasma yielding a short, “croissant-like” heliotail; (2) via magnetohydrodynamic modeling, we can
capture this mixing region, which has potential implications for particle acceleration; (3) current
energetic neutral atom (ENA) observations appear to be insufficient for distinguishing the true shape of
the heliotail, but future ENA-focused missions, such as IMAP, will have the capability to determine the
shape of the heliotail; (4) ENA observations of the heliotail and Lyman-alpha observations may also be
able to reveal the properties of the interstellar magnetic field

How to cite: Kornbleuth, M., Opher, M., Powell, E., Onubogu, C., Ma, X., and Richardson, J.: Investigating the Complex Heliosheath of our Heliospheric Shield, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2490, https://doi.org/10.5194/egusphere-egu24-2490, 2024.

EGU24-3154 | Orals | ST1.14

Solar wind magnetic holes in the inner and outer heliosphere 

Tomas Karlsson, Henriette Trollvik, Andrew Dimmock, Lina Hadid, Michiko Morooka, Martin Volwerk, Giuseppe Arró, Hadi Madanian, Francesco Callifano, Luis Preisser, Diana Rojas Castillo, and Cyril Simon-Wedlund

Solar wind magnetic holes are small-scale, isolated decreases of the magnetic field strength. They are commonly divided into two types, linear and rotational magnetic holes, based on the rotation of the magnetic field vector from one side of the hole to the other. We present Solar Orbiter, Parker Solar Probem and MESSENGER measurements of magnetic holes from the inner heliosphere (~0.1-1.0 AU) and Cassini measurements from the outer heliosphere (~9 ̶ 10 AU). We compare properties such as rate of occurrence, and distributions of scale size, depth, and amount of magnetic field rotation, and discuss the findings in terms of local generation of magnetic holes, versus transport of magnetic holes generated in the inner heliosphere. We also discuss the relative importance of magnetic holes in interacting with the magnetospheres of planets in the inner and outer heliosphere.

How to cite: Karlsson, T., Trollvik, H., Dimmock, A., Hadid, L., Morooka, M., Volwerk, M., Arró, G., Madanian, H., Callifano, F., Preisser, L., Rojas Castillo, D., and Simon-Wedlund, C.: Solar wind magnetic holes in the inner and outer heliosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3154, https://doi.org/10.5194/egusphere-egu24-3154, 2024.

EGU24-3515 | Posters on site | ST1.14

SciQLop:  a tool suite to facilitate multi-mission data browsing and analysis 

Alexis Jeandet, Nicolas Aunai, Benjamin Renard, Vincent Génot, Patrick Boettcher, Myriam Bouchemit, Bayane Michotte de Welle, Ambre Ghisalberti, and Nicolas André

The SCIentific Qt application for Learning from Observations of Plasmas (SciQLop) project allows to easily discover, retrieve, plot and label in situ space physic measurements stored on remote servers such as Coordinated Data Analysis Web (CDAWeb) or Automated Multi-Dataset Analysis (AMDA).  Analyzing data from a single instrument on a given mission can raise some technical difficulties such as finding where to get them, how to get them and sometimes how to read them.  Thus building for example a machine-learning pipeline involving multiple instruments and even multiple spacecraft missions can be very challenging. Our goal here is to remove all these technical difficulties without sacrificing performances to allow scientist to focus on data analysis.

The SciQLop project is composed of the following tools:

  • Speasy: An easy to use Python package to retrieve data from remote servers with multi-layer cache support.
  • Speasy_proxy: A self-hostable, chainable remote cache for Speasy written as a simple Python package.
  • Broni: A Python package which finds intersections between spacecraft trajectories and simple shapes or physical models such as magnetosheath.
  • Orbit-viewer: A Python graphical user interface (GUI) for Broni.
  • TSCat: A Python package used as backend for catalogs of events storage.
  • TSCat-GUI: A Python graphical user interface (GUI).
  • SciQLop-GUI: An extensible and efficient user interface to visualize and label time-series with an embedded IPYthon terminal.

While some components are production ready and already used for science, SciQLop is still being developped and the landscape is moving quite fast.

In this poster we will demonstrate how the SciQLop project makes masive in-situ data analysis simple and fast and we will also take the oportunity to exchange ideas with our users.

How to cite: Jeandet, A., Aunai, N., Renard, B., Génot, V., Boettcher, P., Bouchemit, M., Michotte de Welle, B., Ghisalberti, A., and André, N.: SciQLop:  a tool suite to facilitate multi-mission data browsing and analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3515, https://doi.org/10.5194/egusphere-egu24-3515, 2024.

EGU24-3620 | Orals | ST1.14 | Highlight | Hannes Alfvén Medal Lecture

Multiscale matters: when coupling across multiple scales drives the dynamics of solar system plasmas 

Sandra Chapman

The sun, solar wind and magnetospheres exhibit non-linear processes that can couple across a broad range of space and time scales. These multiscale processes can be central to the dynamics of far from equilibrium plasmas, where collisionless processes dominate. This talk offers highlights from two interconnected approaches to advancing our understanding of multi-scale processes in solar system plasmas.

From the plasma physics: If sufficient simplifications can be made, we can study the plasma dynamics from first principles. The non-linear scattering and acceleration of energetic particles in current sheets, by wave particle interactions, and in shocks, can be approached from non self-consistent single particle dynamics allowing the full non-linear physics, including low-dimensional chaos, to be considered. The physics of shocks, reconnection, and its interplay with turbulence can be approached by fully kinetic self-consistent simulations, albeit with restrictions on physical dimension and the range of scales resolved. If bursty energy and momentum transport is an emergent process, then it can be captured by reduced models.

From the data: The full dynamics is revealed in all its richness in observations. A wealth of in-situ and remote observations are available from the fastest physical timescales of interest to across multiple solar cycles. In principle, these afford the study of specific physical process such as reconnection and turbulence, and system-scale processes such as the dynamics of magnetospheres, all of which are fully multiscale and non-linear. In practice, determining the physics from observations relies upon establishing robust, reproducible patterns and relationships from multipoint data in these inhomogeneously sampled, non time-stationary systems. As well as providing fundamental physical insights, these can deliver quantitative estimates of space weather risk.

How to cite: Chapman, S.: Multiscale matters: when coupling across multiple scales drives the dynamics of solar system plasmas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3620, https://doi.org/10.5194/egusphere-egu24-3620, 2024.

EGU24-3626 | Posters on site | ST1.14

A regular clock for the solar cycle variation of sunspot and geomagnetic activity 

Sandra Chapman and Thierry Dudok de Wit

Sunspot records reveal that whilst the sun has an approximately 11 year cycle of activity, no two cycles are of the same duration. Since this activity is a direct driver of space weather at earth, this presents an operational challenge to quantifying space weather risk. The sunspot number record can be used to map the variable cycle length onto a regular 'clock' and this mapping reveals in each cycle a clear active-quiet switch-off and quiet-active switch-on of activity, with around 2% of extreme space weather events occurring within the quiet intervals of the cycles over the last 155 years [1]. Some of the most extreme geomagnetic storms have occurred around the switch-on and switch-off times, rather than at solar maximum, motivating their determination and prediction. The times of the switch-on/off can be approximately determined directly from the sunspot time-series [2] so that future switch-on and switch-off times can be directly identified in model predictions for future solar activity as characterized by sunspot number. The clock supports charting – a tool to integrate observational estimates of risk (observed events and their likelihood) with narrative reports of impacts on technological systems to improve our understanding of space weather hazard. The sunspot number Hilbert transform phase is found to correspond to solar-cycle scale evolution of sunspot latitudinal bands, so that there is a direct relationship between the well known sunspot ‘butterfly pattern’ and the intensity and character of geomagnetic activity and its switch-on/off [3].

[1] S. C. Chapman, S. W. McIntosh, R. J. Leamon, N. W. Watkins, Quantifying the solar cycle modulation of extreme space weather, Geophysical Research Letters, (2020) doi:10.1029/2020GL087795 

[2] S. C. Chapman, Charting the Solar Cycle, Front. Astron. Space Sci. - Space Physics,  (2023) doi:10.3389/fspas.2022.1037096

[3] S. C. Chapman, T. Dudok de Wit, A solar cycle clock for extreme space weather (preprint, 2024) doi:10.21203/rs.3.rs-3672243/v1

 

How to cite: Chapman, S. and Dudok de Wit, T.: A regular clock for the solar cycle variation of sunspot and geomagnetic activity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3626, https://doi.org/10.5194/egusphere-egu24-3626, 2024.

Understanding the large-scale structure and evolution of coronal mass ejections (CMEs) is essential for accurately forecasting their space weather impacts at Earth and other planets. There are several open issues concerning the global shape, evolution and magnetic configuration of CME flux ropes as they travel through the heliosphere, notably their deformation, erosion, deflection, rotation and coherence. Extensive progress is currently made in both regimes of observations and modeling. All types of models, being numerical, empirical or analytical, have their advantages and disadvantages. While 3D-MHD models capture the physics of CMEs in detail, very fast models can map the full parameter space and can quickly interpret multipoint CME flux rope observations. With solar cycle 25 on the rise, the spacecraft fleet Parker Solar Probe, Solar Orbiter, BepiColombo, STEREO-A, and several probes at L1 now routinely provide us with multi-spacecraft lineup observations of the same CME event. This makes it possible to combine remote sensing and in situ observations to constrain CME models. However, entirely novel types of observations are driving the field forward now. In June and September 2022, Parker Solar Probe observed CMEs in situ at 0.07 AU, setting new records for the observations of CMEs closest to the Sun. In 2023, STEREO-A acted as the first sub-L1 monitor while passing the Sun-Earth line. In March 2022, Solar Orbiter was able to measure the magnetic flux rope of a CME in situ prior to Earth impact with a long lead time, for the first time in space science history. From early 2025, Solar Orbiter will provide out-of-ecliptic measurements of CMEs, which is a much needed perspective to constrain large-scale CME flux rope models. The PUNCH mission will provide polarized heliospheric images of CMEs, which leads to the exciting possibility to determine the handedness and possibly flux rope type from remote sensing observations. Distant retrograde mission concepts like MIIST and HENON could routinely sample CMEs at spatial separations of 1-10° and 0.01 to 0.1 AU in the 2030s, when also ESA Vigil is expected to start operations.

How to cite: Möstl, C.: On the current understanding of large-scale flux ropes within solar coronal mass ejections, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4025, https://doi.org/10.5194/egusphere-egu24-4025, 2024.

EGU24-4200 | Orals | ST1.14

Prediction of the Structure of the Corona for the 2024 Total Solar Eclipse:  A Continuously Updated Model 

Jon Linker, Cooper Downs, Ronald Caplan, Emily Mason, Michal Ben-Nun, Ryder Davidson, Roberto Lionello, Erika Palmerio, Andres Reyes, Pete Riley, Viacheslav Titov, Tibor Torok, and James Turtle

Total solar eclipses offer an unparalleled opportunity to observe the low and middle corona.  As is our tradition, the solar physics team at Predictive Science is predicting the structure of the solar corona for the April 8, 2024 total solar eclipse, using a magnetohydrodynamic (MHD) model of the corona.  The model incorporates thermodynamic transport terms and employs a wave-turbulence-driven (WTD) description of coronal heating and solar wind acceleration.  Our previous coronal predictions employed relaxed MHD solutions corresponding to a boundary condition based on a single photospheric magnetic map, incorporating data that at best was measured 10 to 14 days prior to the eclipse.


This year, we introduce a new paradigm:  A continuously updated prediction based on a time-evolving model.  To accomplish this near-real time description, we have incorporated 3 new elements:  (1) a time-evolving MHD model driven by evolution of the photospheric magnetic field,  (2) an automated method for energizing the non-potential corona near polarity inversion lines that evolve in time, and (3) The Open-source Flux Transport (OFT) model, that assimilates near-real time surface magnetic flux observations from SDO HMI as well as low-latency observations from the Solar Orbiter PHI instrument made away from the Sun–-Earth line.

This presentation will give an overview of the entire prediction effort and describe the time-dependent coronal dynamical features that appear in the solutions.

Research Supported by NASA and NSF.  Computational resources provided by the NSF ACCESS program and the NASA Advanced Supercomputing division at Ames.

How to cite: Linker, J., Downs, C., Caplan, R., Mason, E., Ben-Nun, M., Davidson, R., Lionello, R., Palmerio, E., Reyes, A., Riley, P., Titov, V., Torok, T., and Turtle, J.: Prediction of the Structure of the Corona for the 2024 Total Solar Eclipse:  A Continuously Updated Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4200, https://doi.org/10.5194/egusphere-egu24-4200, 2024.

EGU24-5009 | Posters on site | ST1.14 | Highlight

The science of our Sun’s astrosphere: in-situ ions from the Voyagers and remotely sensed ENAs from Cassini 

Konstantinos Dialynas, Stamatios Krimigis, Robert Decker, Matthew Hill, and Romina Nikoukar

The path-breaking observations of the two Voyager spacecraft over the past two decades, have revolutionized our understanding of interplanetary space within our solar bubble. The crossings of the Voyagers (V1, V2) of the Termination Shock (TS) led to the discovery of the previously unknown reservoir of ions and electrons that constitute the heliosheath, whereas the combination of in-situ particle and fields measurements from V1 and V2 with remote images of ~5.2 to 55 keV ENAs from Cassini/INCA at 10 AU, revealed a number of previously unanticipated heliospheric structures such as the “Belt”, a region of enhanced particle pressure inside the heliosheath. The V1 and V2 crossings of the heliopause (HP) pinpointed the extent of the upwind heliosphere’s expansion into the VLISM and its rough symmetry. We will provide a brief discussion for the contribution of the >28 keV Voyager 1 & 2/LECP observations that established “ground truth” to the ENA images from Cassini/INCA towards addressing longstanding, fundamental questions for the heliosphere’s interaction with the Very Local Interstellar Medium (VLISM), such as the shape and properties of the ion spectra inside the heliosheath, the acceleration of low energy ions and Anomalous Cosmic Rays (ACR) in the heliosheath, the pressure balance and plasma beta in the heliosheath that dictate the magnitude of the magnetic field upstream at the heliopause, the thickness of the heliosheath, the effects of the solar cycle through the outward propagating solar wind that result in an “breathing” (inflating and deflating) heliosphere, together with the implications of these measurements towards addressing the global shape of the heliosphere. The crossings of V1 and V2 from the HP revealed that the primary driver of the interaction of the heliosphere with the VLISM is the pressure of the interstellar (IS) magnetic field, whereas this interaction is more complex than previously thought: The V1 crossing of the HP was associated with the discovery of a flow stagnation region, possibly due to flux tube interchange instability. Further, V1 showed the existence of a radial inflow of low energy ions within the HS for ~9 AU before the HP, and a small radial outflow over a spatial scale of at least 33 AU past the HP, that corresponds to an ion population leaking from the HS into interstellar space. The use of these observations drive the requirements for the particle and fields measurements for a possible future Interstellar Probe mission.

How to cite: Dialynas, K., Krimigis, S., Decker, R., Hill, M., and Nikoukar, R.: The science of our Sun’s astrosphere: in-situ ions from the Voyagers and remotely sensed ENAs from Cassini, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5009, https://doi.org/10.5194/egusphere-egu24-5009, 2024.

EGU24-5343 | Orals | ST1.14

Implications of Energetic Neutral Atoms observed with IBEX-Lo for the pressure balance in the heliosphere 

André Galli, Peter Wurz, Nathan S. Schwadron, Eberhard Möbius, Stephen A. Fuselier, Justyna M. Sokół, Maciej Bzowski, Paweł Swaczyna, Kostas Dialynas, and David J. McComas

Energetic Neutral Atoms (ENAs) from the heliosphere are a unique means to remotely image the boundary regions of our heliosphere. NASA's Interstellar Boundary Explorer (IBEX) has been very successful in measuring these ENAs since 2008 at energies from tens of eV to 6 keV.

The ENA low energy range from tens of eV to solar wind energy (roughly 1 keV) has been sampled throughout an entire solar cycle with the IBEX-Lo ENA imager. This enables us to study the physical implications for the structure of the heliosphere and for the parent proton populations in the heliosheath and other plasma regions that give rise to the observed ENAs. Here, we will discuss in particular the implications of the measured ENA intensities for the plasma pressure balance at the heliospheric boundary.

How to cite: Galli, A., Wurz, P., Schwadron, N. S., Möbius, E., Fuselier, S. A., Sokół, J. M., Bzowski, M., Swaczyna, P., Dialynas, K., and McComas, D. J.: Implications of Energetic Neutral Atoms observed with IBEX-Lo for the pressure balance in the heliosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5343, https://doi.org/10.5194/egusphere-egu24-5343, 2024.

EGU24-5893 | Posters on site | ST1.14

Measurement of the Composition of the Local Interstellar Cloud with the Interstellar Probe Mission 

Peter Wurz, Rico Fausch, Jonathan Gasser, André Galli, Audrey Vorburger, Pontus Brandt, and Stas Barabash

The proposed Interstellar Probe (IP) spacecraft of NASA will travel through the heliosphere and advance into the local interstellar medium (LISM) within roughly 16 years, i.e., at twice the speed as the Voyager spacecraft. IP will enable the dedicated exploration of the heliospheric boundary by imaging the heliosphere from inside and outside the heliopause, and by directly sampling the unknown LISM. IP will also enable in situ measurements in the undisturbed LISM beyond the heliospheric bow shock or bow wave. The measurement of the chemical composition of the neutral gas in the local interstellar cloud is an important element of the scientific investigations of IP. So far, the chemical composition of the LISM was mostly inferred from pickup ions in the solar wind, from anomalous cosmic rays, and from spectroscopic observations of nearby stars. We are designing a highly specialized mass spectrometer to measure the neutral gas of the LISM in situ at these extremely low densities. The expected species to be recorded are H, He, C, N, O, Ne, Na, Mg, Al, Si, P, S, Ar, Ca, and Fe. This list of species allows to derive astrophysical important element ratios, like the Ne/O ratio. In addition, this mass spectrometer will measure the isotope composition of D/H, 3He/4He, 22Ne/20Ne, and 36Ar/38Ar of the LISM with unprecedented accuracy. These measurements will take advantage of the long duration of the IP mission, allowing for long integration times. The design of the instrument will be presented, together with estimated signals, and the operation scenario for the 50-year IP mission.

How to cite: Wurz, P., Fausch, R., Gasser, J., Galli, A., Vorburger, A., Brandt, P., and Barabash, S.: Measurement of the Composition of the Local Interstellar Cloud with the Interstellar Probe Mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5893, https://doi.org/10.5194/egusphere-egu24-5893, 2024.

A new era of spacecraft probing the inner heliosphere make now possible the study of the spatial distribution of solar energetic particle (SEP) events closer to the Sun. Recent missions, such as Solar Orbiter, along with the constellations of spacecraft near 1 au facilitate the study of the radial dependence of SEP parameters, such as the peak intensity and spectrum. In this work, we use the solar energetic electrons (SEE) measured by the MESSENGER mission from 2011 to 2015 to derive statistical results about the radial dependence of some SEE parameters, which are compared with the results from Solar Orbiter near its first nominal perihelion in March 2022.  The main conclusions are: (1) There is a wide variability in the radial dependence of the electron peak intensities, but on average and within uncertainties, the radial dependence can be expressed as R-3, being R the heliocentric distance to the Sun. (2) Between near 0.3 au and 1 au, the energy spectrum of the near-relativistic electrons becomes softer.

We also analyse the relations between the solar activity and the SEE peak intensities measured by MESSENGER, STEREO and ACE spacecraft during 2010-2015. We investigate the 3D early kinematic profile of the CME and associated wave and determine their main morphological (size) and dynamic (propagation and expansion speeds, acceleration) properties and study their relationship with the particle (electron and proton) energies and timing measured in situ. A summary of the results, implications for the Space Weather research, and comparison with previous works is presented.

How to cite: Rodríguez-García, L.: Acceleration and transport of solar energetic particles in the inner heliosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6213, https://doi.org/10.5194/egusphere-egu24-6213, 2024.

EGU24-6368 | ECS | Orals | ST1.14

Effect of magnetic field inclination on SDO/AIA 1600 Å emission 

Ismo Tähtinen, Alexei Pevtsov, Timo Asikainen, and Kalevi Mursula

A strong correlation between the intensity of chromospheric emissions and the (unsigned) photospheric magnetic field strength has been established in several studies. These studies have typically been based on line-of-sight (LOS) observations of the magnetic field, while measurements of the full 3D magnetic vector, which provide the true field strength and the orientation of magnetic field line, have not been studied in this context. Thus, the possible effect of magnetic field inclination on chromospheric emissions has remained hidden so far.

We study here how the inclination of the photospheric magnetic field, as measured by the full 3D magnetic vector from the Solar Dynamics Observatory (SDO) Helioseismic Magnetic Imager (HMI), affects the FUV emission at around 1600 Å from SDO Atmospheric Imaging Assembly (AIA). We analyze 1168 co-temporal observations by the two instruments from 2014 to 2017. We focus on magnetically active regions outside the sunspots (e.g., plages and network) close to the solar disk center.

We find that the AIA 1600 Å emission typically decreases with increasing (more horizontal) inclination. For all inclinations, AIA 1600 Å emission increases with increasing magnetic field to a maximum emission and then slowly decreases for larger field strengths. Maximum emission and the related field strength decrease with inclination. Above this field strength of maximum emission, the emission decouples from the field strength and is mainly governed by inclination. For fixed AIA emission level the associated magnetic field strength decreases with inclination. The difference in the median magnetic field strength can be more than 200 G (about a factor of two) for the same emission level between almost radial (γLoc ≈ 15°) and nearly-horizontal (γLoc ≈ 60°) fields.


AIA 1600 Å emission and magnetic field inclination are bimodally distributed with constant magnetic field strength below 1000 G. One population has a high AIA emission and a roughly vertical magnetic field, the other a lower emission and a horizontal field. The population consisting of less bright pixels with horizontal field is typically found at the border of active region, while the population with bright pixels with a vertical field occupy the bulk of an active region.

Our results show that the chromospheric FUV emission at around 1600 Å is strongly influenced by the inclination of the magnetic field. These results are important, for example, for models aiming to reconstruct the solar spectral irradiance or the past solar activity based on chromospheric emissions. These models would be more accurate if they took into account the effect of inclination of the magnetic field on FUV emissivity.

How to cite: Tähtinen, I., Pevtsov, A., Asikainen, T., and Mursula, K.: Effect of magnetic field inclination on SDO/AIA 1600 Å emission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6368, https://doi.org/10.5194/egusphere-egu24-6368, 2024.

EGU24-6567 | ECS | Posters on site | ST1.14

Inferring the Interstellar Magnetic Field Direction from Energetic Neutral Atom Observations of the Heliotail 

Marc Kornbleuth, Merav Opher, Maher Dayeh, Justyna Sokol, Drew Turner, Igor Baliukin, Kostas Dialynas, and Vladislav Izmodenov

Determining the magnitude and direction of the interstellar magnetic field (BISM) is a longstanding problem. To date, some methods to infer the direction and magnitude have utilized best fit models to the positions of the termination shock and heliopause measured by Voyager 1 and 2. Other models use the circularity of the IBEX Ribbon assuming a secondary energetic neutral atom (ENA) mechanism. Previous studies have revealed that the BISM organizes the orientation of the heliotail with respect to the solar meridian. Here, we propose a new way to infer the direction of the BISM based on ENA observations of the heliotail. IBEX observations of the heliotail have revealed high-latitude lobes of enhanced ENA flux at energies >2 keV. Analyses showed that the high latitude lobes are nearly aligned with the solar meridian, while also exhibiting a rotation with solar cycle. We show using steady state solar wind conditions that the inclination of the lobes reproduced with commonly used values for the angle (αBV) between BISM and the interstellar flow in the hydrogen deflection plane (40 deg. < αBV < 60 deg.) is inconsistent with the IBEX ENA observations. We report that 0 deg. < αBV < 20 deg. is required to reproduce the heliotail lobe inclinations observed by IBEX. Additionally, we find that the variation of the solar magnetic field magnitude with solar cycle causes the longitudinal rotation of the lobes observed by IBEX by affecting the inclination of the lobes.

How to cite: Kornbleuth, M., Opher, M., Dayeh, M., Sokol, J., Turner, D., Baliukin, I., Dialynas, K., and Izmodenov, V.: Inferring the Interstellar Magnetic Field Direction from Energetic Neutral Atom Observations of the Heliotail, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6567, https://doi.org/10.5194/egusphere-egu24-6567, 2024.

EGU24-7182 | ECS | Orals | ST1.14

Changes in Photospheric Lorentz Force in Eruptive and Confined Solar Flares 

Samriddhi Sankar Maity, Ranadeep Sarkar, Piyali Chatterjee, and Nandita Srivastava

Solar flares are known to leave imprints on the magnetic field at the photosphere, often manifested as an abrupt and permanent change in the downward-directed Lorentz force in localized areas inside the active region. Our study aims to differentiate eruptive and confined solar flares based on the vertical Lorentz force variations. We select 26 eruptive and 11 confined major solar flares (stronger than the GOES M5 class) observed during 2011-2017. We analyze these flaring regions using SHARP vector-magnetograms obtained from the NASA's Helioseismic and Magnetic Imager (HMI). We also compare data corresponding to 2 synthetic flares from a delta sunspot simulation reported in Chatterjee et al. We estimate the change in the horizontal magnetic field and the total Lorentz force integrated over an area around the polarity inversion line (PIL) that encompasses the location of the flare. Our results indicate a rapid increase of the horizontal magnetic field along the flaring PIL, accompanied by a significant change in the downward-directed Lorentz force in the same vicinity. Notably, we find that all the confined events under study exhibit a total change in Lorentz force of < 1.8 x 10^22 dyne. This threshold plays an important factor in effectively distinguishing eruptive and confined flares. Further, our analysis suggests that the change in total Lorentz force also depends on the reconnection height in the solar corona during the associated flare onset. The results provide significant implications for understanding the flare-related upward impulse transmission for the associated coronal mass ejection.

How to cite: Maity, S. S., Sarkar, R., Chatterjee, P., and Srivastava, N.: Changes in Photospheric Lorentz Force in Eruptive and Confined Solar Flares, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7182, https://doi.org/10.5194/egusphere-egu24-7182, 2024.

EGU24-9162 | ECS | Posters on site | ST1.14

Study of brightness profiles for different coronal structures 

Andrea Lienhart, Greta M. Cappello, Manuela Temmer, Guiseppe Nistico, Russell Howard, Angelos Vourlidas, and Volker Bothmer

Extended coronal structures can be observed in white-light using coronagraphs or heliospheric imagers. These instruments observe the Thomson-scattered emission by the electrons of that feature. The scattered emission shows a dependence on the geometry between the Sun, the observer and the scattering structure. The maximum scattering efficiency is obtained on a circle whose diameter is equal to the distance between the Sun and the observer (called Thomson surface). The aim of this study is to investigate the brightness profile of different coronal features in terms of the Thomson-scattering geometry using data from the Wide-Field Imager for Solar Probe (WISPR) aboard Parker Solar Probe (PSP). Due to the special orbit of PSP, the size of the Thomson surface is constantly changing. Brightness curves are calculated for features with different properties, e.g. static structures such as helmet streamers, dynamic but compact structures such as streamer blobs and expanding structures such as coronal mass ejections. The results are then compared with raytracing simulations.

How to cite: Lienhart, A., Cappello, G. M., Temmer, M., Nistico, G., Howard, R., Vourlidas, A., and Bothmer, V.: Study of brightness profiles for different coronal structures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9162, https://doi.org/10.5194/egusphere-egu24-9162, 2024.

EGU24-10241 | ECS | Posters on site | ST1.14

Intermittency in interplanetary coronal mass ejections observed by Parker Solar Probe and Solar Orbiter 

Julia Ruohotie, Simon Good, and Emilia Kilpua

ICMEs are often observed as large-scale flux ropes with smoothly varying magnetic fields, but a spectrum of fluctuations is present at smaller scales. A well-known feature of solar wind plasma is that, when moving from large to small scales, distributions of fluctuation amplitudes become more non-Gaussian. This behaviour is a manifestation of intermittency, i.e., an increasingly uneven spatial distribution of energy with decreasing scale in the plasma. While intermittency has been studied extensively in the solar wind, few studies have considered intermittency within ICMEs.

This presentation introduces a statistical study of intermittency of magnetic field fluctuations within ICMEs observed by Parker Solar Probe and Solar Orbiter at heliospheric distances ranging from 0.2 to 1 AU. The analysis uses structure functions with kurtosis as the main measure of intermittency. The analysis is repeated within ICME sheath regions, as well as in the upstream and downstream solar wind. The results obtained from these plasma environments are compared to the ones obtained within ICMEs. Finally, the connection between intermittency and heliospheric distance, cross-helicity, and residual energy is investigated.

How to cite: Ruohotie, J., Good, S., and Kilpua, E.: Intermittency in interplanetary coronal mass ejections observed by Parker Solar Probe and Solar Orbiter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10241, https://doi.org/10.5194/egusphere-egu24-10241, 2024.

EGU24-10428 | Posters on site | ST1.14

Towards a Semi-Analytical Model of the Long-Term Variations of the Heliospheric Structures 

Giuseppe La Vacca, Stefano Della Torre, and Massimo Gervasi

When developing a model to accurately predict the solar modulation of galactic cosmic rays, it is crucial to consider the global characteristics of the heliosphere. The dynamics and variability of the boundaries of the heliosphere have a significant impact on the long-term variation of cosmic rays, even at Earth's location. Therefore, it is highly desirable to have a global, time-dependent, and user-friendly heliospheric structure modelization. With this aim, we developed a semi-analytical, data-driven model that uses a simplified approach for solving the solar wind dynamics through the heliosphere, including the effect of the pick-up ions on the termination shock. The model also uses measurements of the energetic neutral atoms' spectra at 1AU to determine the distance of the heliopause. The model's predictions have been compared with the observations of the Voyager probes.

How to cite: La Vacca, G., Della Torre, S., and Gervasi, M.: Towards a Semi-Analytical Model of the Long-Term Variations of the Heliospheric Structures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10428, https://doi.org/10.5194/egusphere-egu24-10428, 2024.

EGU24-11666 | Posters on site | ST1.14

Observations and modelling of the solar wind composition variations 

Alexis Rouillard, Paul Lomazzi, Simon Thomas, Victor Réville, Bahaeddine Gannouni, Nicolas Poirier, Jean-Baptiste Dakeyo, and Chuanpeng Hou

The physical mechanisms that regulate the abundance of heavy ions in the solar wind are not well understood. Variations in composition are measured in the charge state of heavy ions as well as the abundance of alpha particles and of elements with low first ionisation potential (FIP). The ionisation state and the abundance of heavy ions remain unchanged beyond the solar corona in the solar wind. Since the slow and fast solar winds have very different compositions, the slow wind being enriched in low-FIP elements, it has been argued that they must form through different processes in the solar corona. We analyse solar wind data taken in situ at different points in the inner heliosphere by Parker Solar Probe, Solar Orbiter and ACE to study the relation between ion abundances and solar wind properties (focusing on plasma moments, cross-helicity and non-thermal particles). This leads us to classify the different solar wind types according their composition and Alfvénicity during the different phases of the solar cycle. We then compare this classification with recent results of a new multi-species model of the solar corona and solar wind to study the various mechanisms potentially controlling solar wind composition, including diffusion processes and wave-particle interactions, to regulate heavy ion abundances. This work was funded by the ERC SLOW SOURCE project.

How to cite: Rouillard, A., Lomazzi, P., Thomas, S., Réville, V., Gannouni, B., Poirier, N., Dakeyo, J.-B., and Hou, C.: Observations and modelling of the solar wind composition variations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11666, https://doi.org/10.5194/egusphere-egu24-11666, 2024.

EGU24-11838 | Posters on site | ST1.14

Comparison of geomagnetic activity in solar cycle 12 and 13 with that in cycle 23 and 24. 

Boian Kirov, Katya Georgieva, Vladimir Obridko, and Simeon Asenovski

This study compares the geomagnetic activity observed during the last two secular solar activity maxima: solar cycles 12 and 13,  and 23 and 24, respectively, highlighting the differing patterns of dual and single maxima. In sunspot cycles 12 and 13, we observe a distinct dual-maximum pattern in geomagnetic activity. This pattern contrasts sharply with the singular peaks evident in sunspot cycles 23 and 24. As is well known, the dual peaks in the geomagnetic activity during a sunspot cycle result from the action of two different geoeffective manifestations of solar activity. The peak around sunspot maximum is driven by the Coronal Mass Ejections (CMEs) which are maximium in number and intensity in sunspot maximum. The second peak is due to high-speed solar wind streams (HSS’s) originating from extended coronal holes which maximize during the sunspot declining phase.

This well studied picture is observed during the secular solar minimum between the 19th and 20th centuries (sunspot cycles 12 and 13). In contrast, sunspot cycles 23 and 24 in the minimum between the 20th and 21st centuries present a different scenario. Despite reaching sunspot maxima, these cycles did not witness corresponding peaks in geomagnetic activity. Our research focuses on unraveling the reasons behind the absence of a geomagnetic peak concurrent with the solar activity maxima in these latter cycles

How to cite: Kirov, B., Georgieva, K., Obridko, V., and Asenovski, S.: Comparison of geomagnetic activity in solar cycle 12 and 13 with that in cycle 23 and 24., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11838, https://doi.org/10.5194/egusphere-egu24-11838, 2024.

EGU24-12140 | ECS | Orals | ST1.14

Investigating the absence of stellar CMEs through solar observations  

Alexander G.M. Pietrow, Michael Cretignier, Malcolm K. Druett, Julian D. Alvarado-Gómez, Stefan J. Hofmeister, Meetu Verma, Robert Kamlah, Martina Barlatella, Eliana M. Amazo-Gómez, Ioannis Kontogiannis, Ekatarina Dineva, Alexander Warmuth, Carsten Denker, Katja Poppenhaeger, Olexa Andriienko, Xavier Dumusque, and Mats G. Löfdahl

Coronal Mass Ejections (CMEs) remain a focal point of solar and stellar research due to their significant impact on space weather dynamics and exoplanet habitability. Unfortunately, it has so far proven difficult to measure these events on other stars, with only a handful of confirmed detections. 

On the Sun, strong flares (X1-class and above) are almost always accompanied by a CME. This connection has not been found for other stars, where strong flares are regularly detected without a CME counterpart. To investigate this discrepancy we compare resolved solar observations taken from the Swedish 1-m Solar Telescope with disk-integrated Sun-as-a-star observations taken from the HARPS-N solar telescope. We studied two strong X-class flares, one of which was accompanied by a large (halo)CME, and one that was not. While we have successfully detected flare-related signatures in the activity indices and the radial velocity profile in the Sun-as-a-star data, we detect no significant differences between the two flares and no indications of the presence of the CME, despite other works having previously detected CMEs in Sun-as-a-star data.

We propose that the absence of CME signatures in our data is due to a geometric effect. CMEs far enough away from the disk center are likely to be oriented in such a way that they have limited line-of-sight velocity, and thus cannot produce a strong enough Doppler signature. Therefore, we believe that the lack of observed stellar CMEs is at least partly an observational limitation and does not necessarily represent the underlying physical reality.

How to cite: Pietrow, A. G. M., Cretignier, M., Druett, M. K., Alvarado-Gómez, J. D., Hofmeister, S. J., Verma, M., Kamlah, R., Barlatella, M., Amazo-Gómez, E. M., Kontogiannis, I., Dineva, E., Warmuth, A., Denker, C., Poppenhaeger, K., Andriienko, O., Dumusque, X., and Löfdahl, M. G.: Investigating the absence of stellar CMEs through solar observations , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12140, https://doi.org/10.5194/egusphere-egu24-12140, 2024.

EGU24-13491 | Posters on site | ST1.14

Mirror Mode Storms at the Magnetosheaths of Earth and Mars 

Diana Rojas Castillo, Xochitl Blanco-Cano, Christopher T. Russell, Cyril Simon-Wedlund, and Martin Volwerk

Wave-particle interactions are important in the momentum and energy transfer across a planetary magnetosheath, from the solar wind upstream of the bow shock to the magnetosphere. In the highly perturbed magnetosheath plasma of Earth and Mars, anisotropic ion distributions have enough free energy to drive low-frequency instabilities such as the mirror mode instability. The resulting mirror mode waves are therefore common structures inside those magnetosheaths. In the solar wind, long trains of holes and peaks in the magnetic field magnitude that can last for hours have been reported (Russell et al.,2009; Enriquez-Rivera et al., 2013). In this work, we explore the existence of mirror mode storms in the sheaths of the Earth and Mars like those observed in solar wind regions. We study the characteristics of a few observed storms and possible dependencies on factors such as the plasma beta and distance from the bow shock.  We also study the evolution of the ion distributions associated with mirror mode structures to investigate the waves' origin.

How to cite: Rojas Castillo, D., Blanco-Cano, X., Russell, C. T., Simon-Wedlund, C., and Volwerk, M.: Mirror Mode Storms at the Magnetosheaths of Earth and Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13491, https://doi.org/10.5194/egusphere-egu24-13491, 2024.

EGU24-13547 | ECS | Posters on site | ST1.14

How do inferred statistical properties of switchbacks depend on their definition? 

Srijan Bharati Das and Samuel Badman

Deflections in magnetic fields accompanied by Alfvenic velocity fluctuations are observed in the solar wind and have been termed as switchbacks. While signature of switchbacks have been reported from analysis of Ulysses, Wind and Helios satellites at distances of distances of about 2.4 A.U, 1.0 A.U and 0.3 A.U respectively, since 2018, Parker Solar Probe (PSP) has been providing us a wealth of in-situ measurements within as close as 10 solar radius. Studies on identification of SBs and its properties have boomed in the era of PSP and Solar Orbiter. Open questions regarding the origin of SBs exist which require rigorous quantification of SB properties. However, in order to assess properties across SB events, choices have to be made for how to categorize SBs based on classifying criteria for example, the extent of deflection of the magnetic field compared to the background field (commonly known as the Z-angle), the duration and strength of field or velocity fluctuations during the SB event. A key feature that also requires quantification when classifying SBs is what constitutes the quiet background --- currently common choices include using a running average to build a smooth background and picking out deflections about the smoothened fields or choosing the Parker spiral to construct the background fields. By picking out specific criteria for classifying SBs and analyzing common time periods on the same SB definitions, we investigate to what extent inferred properties depend on the chosen definitions.

How to cite: Das, S. B. and Badman, S.: How do inferred statistical properties of switchbacks depend on their definition?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13547, https://doi.org/10.5194/egusphere-egu24-13547, 2024.

EGU24-13619 | Orals | ST1.14

Evidence of magnetic reconnection observed in the heliosheath by Voyager-2 

Drew Turner, Lingling Zhao, Stefan Eriksson, Benoit Lavraud, John Richardson, and Merav Opher

We present new evidence of active magnetic reconnection observed by Voyager-2 in the heliosheath region beyond the termination shock in the outer heliosphere. Multiple cases have been identified in which significant plasma jets are present during heliospheric current sheet crossings, or sector reversals. Using a combination of the plasma and magnetic field measurements from Voyager-2, candidate events are identified by rotating the magnetic field and plasma velocity vector data into a minimum-variance, LMN-coordinate frame, prior to checking consistency with the Walen relation on the corresponding plasma jet. In the LMN frame, the candidate events are selected based on consistency with the expected geometry of current sheets undergoing magnetic reconnection. The Walen relation further supports consistency with the physics of magnetic reconnection, in which the outflow jets of reconnected field and plasma are ejected from the reconnection site at the Alfvén speed. Error analysis based on limitations of the Voyager-2 data is accounted for throughout the process. In this presentation, we detail the event identification and walk through an example case before presenting several other cases. All combined, confirmation of active magnetic reconnection ongoing in the heliosheath has important implications concerning the heating of plasma in the outer heliosphere and the acceleration of pickup ions and possibly even anomalous cosmic rays.

How to cite: Turner, D., Zhao, L., Eriksson, S., Lavraud, B., Richardson, J., and Opher, M.: Evidence of magnetic reconnection observed in the heliosheath by Voyager-2, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13619, https://doi.org/10.5194/egusphere-egu24-13619, 2024.

EGU24-13951 | ECS | Orals | ST1.14 | ST Division Outstanding Early Career Scientist Award Lecture

Analysing CME observations and simulations with multi-spacecraft techniques 

Erika Palmerio

Coronal mass ejections (CMEs) are humongous structures that permeate the heliosphere as they travel away from the Sun. Beginning their journey from a more-or-less localised region in the solar atmosphere, they expand to many times the size of the Sun through the corona, measure about 0.3 au in radial extent by the time they reach 1 au, and interact with the structured solar wind and other transients to form so-called merged interaction regions in the outer heliosphere. One of the most prominent challenges in heliophysics is the achievement of a complete understanding of the intrinsic structure and evolution of CMEs, in particular of their spatiotemporal variability, which in turn would allow more precise forecasts of their arrival time and space weather effects throughout the heliosphere. The most common methods to detect and analyse these behemoths of the solar system consist of remote-sensing observations, i.e. 2D images at various wavelengths, and in-situ measurements, i.e. 1D spacecraft trajectories through the structure. These data, however, are often insufficient to provide a comprehensive picture of a given event, due to the scarcity of available measurement points and the enormous scales involved. Some ways to circumvent these issues consist of taking advantage of multi-spacecraft observations of the same CME (usually at different heliolongitudes and/or radial distances) and to use simulations to complement the available measurements and/or to investigate the 3D structure of CMEs without constraints on the number of synthetic observers.

In this presentation, we will first provide a review of the advantages of multi-spacecraft observations of CMEs and how they have helped us build the overall picture of CME structure and evolution that forms our current understanding. We will then showcase examples of detailed CME studies, both in the observational and modelling regimes, that have been made possible due to the availability of multi-point measurements. These will include events observed remotely and/or in situ by the latest generation of heliophysics missions, i.e. Parker Solar Probe and Solar Orbiter. Finally, we will speculate on possible future avenues that are worthy of exploring to reach a deeper understanding of CMEs from their eruption throughout their heliospheric journey, especially in terms of novel space missions that may improve not only our knowledge from a fundamental physics standpoint, but also our prediction and forecasting capabilities.

How to cite: Palmerio, E.: Analysing CME observations and simulations with multi-spacecraft techniques, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13951, https://doi.org/10.5194/egusphere-egu24-13951, 2024.

EGU24-14312 | Posters on site | ST1.14

Interstellar Dust Dynamics and the Large-Scale Structure of our Heliosphere 

Mihaly Horanyi, Ethan Ayari, and Antal Juhasz

The local interstellar medium contains plasma, magnetic fields, neutral atoms, cosmic rays, and dust which all influence the heliosphere through interconnected time-dependent and multi-scale processes. The Interstellar Dust Experiment (IDEX) instrument onboard NASA's IMAP mission, to be launched in early 2025, will measure the flux, size distribution, and composition of interstellar (ISD) and interplanetary (IDP) dust particles characterizing the inflowing solid matter from the local interstellar medium reaching the inner heliosphere. IDEX dust detection is based on impact ionization, where elemental and molecular ions are generated in a high-velocity dust impact and analyzed in a time-of-flight (TOF) setup. The size, composition, and the large-scale structure of the heliospheric magnetic fields strongly influence the propagation of the charged ISD particles, including the effects of the so-called heliospheric filtering that prevents small ISD particles from entering the heliosphere. We report on the status of our modeling results and predictions for the expected IDEX measurements. 

 

 

 

 

 

 

 

 

How to cite: Horanyi, M., Ayari, E., and Juhasz, A.: Interstellar Dust Dynamics and the Large-Scale Structure of our Heliosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14312, https://doi.org/10.5194/egusphere-egu24-14312, 2024.

EGU24-14730 | Posters on site | ST1.14

Solar magnetic field and the correlation between sunspot activity and Earth atmospheric parameters 

Katya Georgieva, Svetlana Veretenenko, Boian Kirov, and Simeon Asenovski

Sun is the main energy source in the vicinity of the Earth. The terrestrial atmosphere is governed by the energy it receives from the Sun. Many studies during the last two centuries have demonstrated correlations between solar activity and atmospheric parameters.  The problem is that these correlations, even if highly statistically significant, are not stationary. They may strengthen, weaken, disappear, and even change sign depending on the time period.

In earlier studies it has been found that the sign of the correlations in the Northern hemisphere depends on the prevailing large-scale atmospheric circulation. According to the Vangengeim–Girs classification, there are three main forms of atmospheric circulation: W (zonal or westerly), C (meridional), and E (easterly) for the Atlantic–Eurasian sector, as well as three similar forms: Z, M1, and M2 for the Pacific–American sector. It has been also found that the reversals of the correlations between solar activity and atmospheric parameters is preceded by (or coincides with) the turning points in the evolution of the large-scale circulation forms and mainly of the meridional forms C and M1.

The epochs of large-scale circulation are in turn affected by the stratospheric polar vortex (a large-scale circulation pattern in the stratosphere which develops during polar winter), so the changes in circulation epochs may be associated with the changes in the state of the vortex which can affect the troposphere-stratosphere interaction via planetary waves. If the zonal wind velocity in the vortex exceeds a critical value, planetary waves propagating upward can be reflected back to the troposphere. Under a weak vortex, planetary waves propagate to upper atmospheric levels. Both the circulation epochs and the state of the vortex have cyclic variations with a period of about 60 years.

Two types of solar activity agents are supposed to influence the state of the polar vortex: solar UV irradiance, and energetic particles, mostly electrons, which are trapped in the Earth’s magnetosphere and during geomagnetic disturbances are accelerated and precipitate into the atmosphere. They are related to the two components of the solar magnetic field which is the basis of solar activity. These two components have opposite effects on the stratospheric polar vortex. Here we demonstrate that the relative variations of these two components are in antiphase and oscillate with a period of about 60 years, ultimately determining the correlations between sunspot activity and atmospheric parameters.

How to cite: Georgieva, K., Veretenenko, S., Kirov, B., and Asenovski, S.: Solar magnetic field and the correlation between sunspot activity and Earth atmospheric parameters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14730, https://doi.org/10.5194/egusphere-egu24-14730, 2024.

EGU24-15074 | Posters on site | ST1.14

Using STEREO-A data from April to November 2023 as a sub-L1 monitor 

Eva Weiler, Christian Möstl, Emma E. Davies, Tanja Amerstorfer, Ute V. Amerstorfer, Hannah T. Rüdisser, Rachel L. Bailey, Astrid Veronig, Timothy Horbury, Noé Lugaz, Justin Le Louëdec, and Maike Bauer

Sub-L1 monitors are currently being researched in mission concepts for small satellites and may be deployed on distant retrograde orbits around the Earth in the future. Depending on the location of the sub-L1 monitor, the lead time for the arrival of coronal mass ejections (CMEs) and for determining their geo-effectiveness could be prolonged. If the sub-L1 monitor was to orbit the Earth at a distance of 0.05 AU, as is proposed for the MIIST mission, for example, Dst predictions could be made up to 5 hours in advance. The close encounter of STEREO-A and Wind from April 2023 to November 2023 represents such a constellation, and therefore allows us to investigate potential impacts of future sub-L1 missions. Following the method of Bailey et al. (2020), the data from STEREO-A are mapped to L1, taking into account an expansion of the CME. We then calculate the Dst of the temporally and spatially shifted data, and compare the result with the Dst calculated from L1 solar wind data and the observed Dst. In this way, we can analyse and quantify the implications of sub-L1 monitors on space weather forecasting.

The events included in our study are part of the HELIO4CAST lineup catalog v2.0 (https://helioforecast.space/lineups). The catalogue includes CMEs that were observed by at least two spacecraft such as Solar Orbiter, Parker Solar Probe, BepiColombo, STEREO-A, and Wind. In contrast to single in situ measurements, which do not adequately capture the vast structure of CMEs, the events in the catalogue allow us to study the temporal and spatial evolution of CMEs and improve our current understanding of the large-scale structure of their magnetic flux ropes. In view of the upcoming maximum of solar cycle 25, further multipoint events are expected to be continuously added to the catalogue.

How to cite: Weiler, E., Möstl, C., Davies, E. E., Amerstorfer, T., Amerstorfer, U. V., Rüdisser, H. T., Bailey, R. L., Veronig, A., Horbury, T., Lugaz, N., Le Louëdec, J., and Bauer, M.: Using STEREO-A data from April to November 2023 as a sub-L1 monitor, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15074, https://doi.org/10.5194/egusphere-egu24-15074, 2024.

EGU24-15320 | Orals | ST1.14

 The eight-year solar cycle during the Maunder minimum  

Limei Yan, Fei He, Xinan Yue, Yong Wei, Yuqi Wang, Si Chen, Kai Fan, Hui Tian, Jiansen He, Qiugang Zong, and Lidong Xia

The Maunder minimum (1645–1715 AD) is a representative grand solar minimum with highly depressed sunspot activity and coincident with the “Little Ice Age” on the Earth. Owing to the limited data quality of the currently used solar activity proxies, the cyclic solar activity variations during the Maunder minimum still need to be explored. By analyzing the red equatorial aurorae recorded in Korean historical books in the vicinity of a low-intensity paleo-West Pacific geomagnetic anomaly, we find clear evidence of an eight-year solar cycle during the Maunder minimum. This result provides a new data source on solar activity and a key constraint to theoretical solar dynamo models. It helps understand the generation mechanism of grand solar minima and the solar-terrestrial relations during the Maunder minimum.

How to cite: Yan, L., He, F., Yue, X., Wei, Y., Wang, Y., Chen, S., Fan, K., Tian, H., He, J., Zong, Q., and Xia, L.:  The eight-year solar cycle during the Maunder minimum , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15320, https://doi.org/10.5194/egusphere-egu24-15320, 2024.

EGU24-15379 | Posters on site | ST1.14

Exploration of Solar Wind Phenomena: Database and Duration Analysis 

Simeon Asenovski, Katya Georgieva, and Boian Kirov

The provided open-access database compiles information on various solar wind types and their durations in near-Earth space, encompassing high-speed solar wind streams, coronal mass ejections, and slow solar wind. The categorization of these different flows relies on criteria derived from experimental data on the primary solar wind parameters. Employing physical conditions, the database precisely delineates the commencement and conclusion of each solar wind event. Its primary objective is to span the last five 11-year solar cycles (cycles 20 to 24) and partially 25, leveraging in situ satellite observations. The study also explores the temporal dynamics of high-speed solar wind streams (HSS) and endeavors to establish their precise duration.

How to cite: Asenovski, S., Georgieva, K., and Kirov, B.: Exploration of Solar Wind Phenomena: Database and Duration Analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15379, https://doi.org/10.5194/egusphere-egu24-15379, 2024.

EGU24-16504 | Posters on site | ST1.14

Unexpected energetic particle observations near the Sun by Parker Solar Probe and Solar Orbiter 

Olga Malandraki, Christina M. S. Cohen, Joe Giacalone, John G. Mitchell, Rohit Chhiber, David J. McComas, Javier Rodríguez -Pacheco, Robert Wimmer-Schweingruber, George C. Ho, Niels Janitzek, and Mihir Desai

Solar Energetic Particles (SEPs) constitute an important contributor to the characterization of the space environment. They are emitted from the Sun in association with solar flares and Coronal Mass ejection (CME)-driven shock waves. SEP radiation storms may have durations from a period of hours to days or even weeks and have a large range of energy spectrum profiles. These events pose a threat to modern technology strongly relying on spacecraft, are a serious radiation hazard to humans in space, and are additionally of concern for avionics and commercial aviation in extreme circumstances. However, our knowledge of the origin, acceleration and transport of these particles from close to the Sun through the interplanetary medium has advanced dramatically in the last 40 years, many puzzles have still remained unsolved due to the scarcity of in situ measurements well inside 1 AU. The Solar Orbiter (SolO) ESA mission and NASA Parker Solar Probe (PSP) pioneering missions have been providing unprecedented measurements of energetic particles in the near-Sun environment. In this work, unexpected energetic particle observations as measured by the PSP Integrated Science Investigation of the Sun (ISʘIS) and the SolO Energetic Particle Detector (EPD) experiments will be presented which revealed surprises that challenge our understanding.

How to cite: Malandraki, O., Cohen, C. M. S., Giacalone, J., Mitchell, J. G., Chhiber, R., McComas, D. J., Rodríguez -Pacheco, J., Wimmer-Schweingruber, R., Ho, G. C., Janitzek, N., and Desai, M.: Unexpected energetic particle observations near the Sun by Parker Solar Probe and Solar Orbiter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16504, https://doi.org/10.5194/egusphere-egu24-16504, 2024.

EGU24-16583 | ECS | Orals | ST1.14

Internal magnetic field structures observed by PSP/WISPR in a filament-related CME event 

Greta Cappello, Manuela Temmer, Angelos Vourlidas, Carlos Braga, Paulett Liewer, Jiong Qiu, Guillermo Stenborg, Athanasios Kouloumvakos, Astrid Veronig, Paulo Penteado, Volker Bothmer, and Iulia Chifu

Parker Solar Probe (PSP; launched in 2018) observes the Sun from unprecedented close-in and out-of-ecliptic orbits. The unique and high-resolution data from the Wide-Field Imager for Solar Probe (WISPR) aboard PSP give us new insights about the initiation and early evolution of Coronal Mass Ejections (CMEs) in the inner Heliosphere. We investigate the morphology and propagation behavior of distinct small-scale structures associated with a CME caused by a filament eruption, together with blobs related to the post-CME current sheet. Within this work we want to answer the following questions: how do the small scale magnetic field structures develop, how do they change in shape over time and what is their relation with the erupting filament and flux rope, respectively. The fast PSP motion at perihelion allows one to have views from different angles of the same event, hence we apply a single-spacecraft triangulation technique to derive coordinates and kinematics of each tracked feature. We find distinct groups of small-scale features which appear to be the building blocks of the global CME. We categorised the small scale magnetic structures based on their morphology and extent in longitude and latitude. We obtained a large range of longitudes among the different blobs related to the CME-aftermath. Thread-bundles are identified in the inner Heliosphere, which might be related to the vertical threads that are seen evolving during the filament eruption. Finally, we discuss on the different global appearances of the CME as observed from 1 AU compared to 0.18 AU (PSP).

How to cite: Cappello, G., Temmer, M., Vourlidas, A., Braga, C., Liewer, P., Qiu, J., Stenborg, G., Kouloumvakos, A., Veronig, A., Penteado, P., Bothmer, V., and Chifu, I.: Internal magnetic field structures observed by PSP/WISPR in a filament-related CME event, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16583, https://doi.org/10.5194/egusphere-egu24-16583, 2024.

EGU24-17105 | ECS | Orals | ST1.14

Orbit 16 observations of SEP events from Parker Solar Probe to STEREO and ACE 

Gabriel Muro and the Parker Solar Probe team

During Parker Solar Probe’s 16th orbit, two solar energetic particle (SEP) events were detected by the Integrated Science Investigation of the Sun (ISʘIS). The spacecraft measuring these SEP events were oriented near-perfectly along the same nominal Parker spiral magnetic field line which connected Earth to the solar source for ambient solar wind speeds. Both events were also observed by STEREO and ACE, which provided the opportunity to examine how SEP velocity dispersion, CME shock arrival, energy spectra, and elemental composition varied during transport from 0.65 and 0.76 AU to ~1 AU.

On 17 July 2023, near the southwestern face of the Sun, the solar magnetic active region 13363 underwent considerable evolution which resulted in the largest SEP event of orbit 16 measured by ISʘIS. Two M5.0+ flares at 23:34 and 00:06 UT coincided with a confined prominence eruption and major halo coronal mass ejection (CME). A similar magnetic evolution occurred on 7 August 2023, at the northwestern limb of the Sun, in the solar magnetic active region 13386 when an M1.4 and X1.4 flare at 19:37 and 20:30, respectively, coincided with a confined prominence eruption and large CME.

We utilized a variety of remote observations from GOES, SDO, and SOHO to characterize the magnetic configuration of the local active regions, estimate low coronal temperature, and discuss confined prominence eruptions as a key particle injection source. The notable result from this multi-spacecraft alignment is that SEP fluence appears qualitatively similar at different radial distances, but heavy ions, such as O and Fe, are depleted in comparison to lighter ions during transport.

How to cite: Muro, G. and the Parker Solar Probe team: Orbit 16 observations of SEP events from Parker Solar Probe to STEREO and ACE, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17105, https://doi.org/10.5194/egusphere-egu24-17105, 2024.

EGU24-17259 | ECS | Orals | ST1.14

Modelling near-Sun solar wind electron distribution functions 

Alfredo Micera, Daniel Verscharen, Jesse Coburn, Jasper Halekas, and Maria Elena Innocenti

We provide a picture of the global dynamics of electrons in the inner heliosphere through the study of non-linear interactions affecting the non-thermal features of the solar wind electron velocity distribution function (VDF).
More than 50 years of in-situ observations of the solar wind have shown that the electron VDF consists of a quasi-Maxwellian core, comprising most of the electrons, and two sparser components, the halo, which is formed by suprathermal and quasi-isotropic electrons, and an escaping beam population, the strahl (Marsch 2006; Halekas et al. 2020).
Recent Parker Solar Probe and Solar Orbiter (SO) observations have confirmed the existence of an additional non-thermal feature: the deficit, i.e., a depletion in the sunward region of the VDF (Berčič et al., 2021a; Halekas et al., 2021). This feature had already been predicted by exospheric models (Lemaire and Scherer, 1971; Maksimovic et al., 2001).
By employing Particle-in-Cell (PIC) simulations, we study electron VDFs that reproduce those typically observed in the inner heliosphere and investigate how the electron deficit contributes to the onset of kinetic instabilities and to heat flux regulation in the solar wind.
The strahl electrons drive oblique whistler waves unstable which scatter them in turn (Verscharen et al., 2019, Micera et al., 2021). Our simulation results show that, as a consequence of these scattering processes, the suprathemral electrons occupy regions of phase space where they fulfil resonance conditions with the parallel-propagating fast-magnetosonic/whistler wave.
The suprathermal electrons lose kinetic energy, resulting in the generation of unstable waves. The sunward side of the VDF, initially depleted of electrons, is thus gradually filled by electrons that are resonant with the triggered whistler waves.
As this initial deviation from thermodynamic equilibrium is reduced, a decrease in the electron heat flux occurs.
Our study provides a mechanism that explains the presence of the regularly observed parallel sunward whistler waves in the heliosphere (Tong et al., 2019), whose origin remains uncertain (Vasko et al., 2020). It also suggests an explanation for recent SO observations of whistler waves, concomitant with distributions in which the three above-described non-thermal features are observed (Berčič et al., 2021b, Coburn et al., 2023).

How to cite: Micera, A., Verscharen, D., Coburn, J., Halekas, J., and Innocenti, M. E.: Modelling near-Sun solar wind electron distribution functions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17259, https://doi.org/10.5194/egusphere-egu24-17259, 2024.

EGU24-18120 | Posters on site | ST1.14

Spectral properties of mesoscale fluctuations in ICMEs 

Simon Good, Anna-Sofia Jylhä, Emilia Kilpua, Timo Makelä, Julia Ruohotie, Juska Soljento, and Jose Suihkonen

ICME plasma fluctuates across a broad range of scales, with fluctuations that display many similar spectral properties to other kinds of solar wind. These fluctuations, which may represent turbulence, waves or structures in the plasma, are not well understood holistically in the ICME context. Using data from Parker Solar Probe and Solar Orbiter, we present analysis of magnetic field spectra from ICME flux ropes at scales between the flux rope radial width and the magnetic field correlation length. The presence of the global flux rope causes significant steepening of the spectra at these scales, with spectral indices as steep as -2. The underlying fluctuations, in contrast, show much shallower spectral slopes. Key properties of the fluctuations are determined and compared to those found at the same scales in other solar wind types. Interpretations of the fluctuations as an energy source for turbulence at smaller scales or as mesoscale ICME substructure are discussed.

How to cite: Good, S., Jylhä, A.-S., Kilpua, E., Makelä, T., Ruohotie, J., Soljento, J., and Suihkonen, J.: Spectral properties of mesoscale fluctuations in ICMEs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18120, https://doi.org/10.5194/egusphere-egu24-18120, 2024.

EGU24-19033 | ECS | Orals | ST1.14

Latitudinal Variation of the Background Solar Wind in the Inner Heliosphere from Multi-Spacecraft Observations 

Nikolett Biro, Andrea Opitz, Zoltan Nemeth, Akos Madar, Aniko Timar, and Gergely Koban

In order to improve the predictions of the ambient solar wind plasma at planets, moons, comets, and interplanetary spacecraft, we are conducting a multi-spacecraft investigation to study the spatial variation and temporal evolution of solar wind structures. Here we present our results on the spatial variation by investigating the impact of latitudinal spacecraft-target separation on extrapolation accuracy. Using ballistically propagated bulk velocity datasets of the ACE, STEREO A, Parker Solar Probe, and Solar Orbiter spacecraft, we perform statistical analyses and case studies. Our findings indicate that a separation of even a few degrees in latitude can introduce errors into propagation accuracy and needs to be taken into account when incorporating in-situ measurements into solar wind forecasting. We further investigate the role of the heliospheric current sheet in this phenomenon by utilizing coronal modeling. The results are useful in supporting out-of-ecliptic solar wind observations and for the improvement of propagation models.

How to cite: Biro, N., Opitz, A., Nemeth, Z., Madar, A., Timar, A., and Koban, G.: Latitudinal Variation of the Background Solar Wind in the Inner Heliosphere from Multi-Spacecraft Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19033, https://doi.org/10.5194/egusphere-egu24-19033, 2024.

EGU24-19576 | ECS | Posters on site | ST1.14

The Carrington Map in H I Ly-alpha Passband Based on ASO-S/LST/SDI 

Shuting Li, Li Feng, and Beili Ying

The Lyman-alpha (Lyα) Solar telescope (LST) is one of the three payloads onboard the Advanced Space-based Solar Observatory (ASO-S) mission. As one of the instruments of LST, the Solar Disk Imager (SDI) works in the Lyα waveband of 121.6 ± 10nm with a field of view (FOV) up to 1.2 R⊙. In this work, we construct the Carrington maps (or so-called synoptic map) of solar Lyα intensities based on full-disk images acquired by SDI. We present two versions of Carrington maps, one is synthesized once in a Carrington cycle, and the other is daily-updated. The former gives the general view of the emission distribution in Lyα during the whole CR, while the latter provides a better near-real-time measurement of the intensity. By establishing the relation between the emission of Lyα in 121.6 nm and He II in 30.4 nm, we provide a possible way to offset the observation gaps of SDI from AIA/304 channel. The radiometric calibration is performed using the cross-calibration method with GOES/EUVS data. To this end, the calibrated carrington map can be applied to constrain the incident emission to the corona in Lyα. Regarding this application, we propose an upgraded version of the carrington map to correct the emission variation caused by eruptions like coronal mass ejections (CMEs) and flares. The comparison between the SDI Carrington map and the magnetogram synoptic map serves as the final example of the application of SDI Carrington map in our work, the locations of different features in line-of-sight magnetic field and in Lyα are directly compared.

How to cite: Li, S., Feng, L., and Ying, B.: The Carrington Map in H I Ly-alpha Passband Based on ASO-S/LST/SDI, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19576, https://doi.org/10.5194/egusphere-egu24-19576, 2024.

EGU24-20141 | Orals | ST1.14

Heliospheric and cosmic dust science with Interstellar Probe and with missions inside the solar system 

Veerle J. Sterken, Silvan Hunziker, Konstantinos Dialynas, Lennart R. Baalmann, Arthur Péronne, Harald Krüger, Peter Strub, Kyung-Suk Cho, James D. Carpenter, Arik Posner, and Pontus Brandt

Cosmic dust particles with sufficiently high charge-to-mass ratios interact with the heliosphere on both global and local scales due to the coupling of the charged dust with the heliospheric plasma. They are the fingerprints of heliospheric phenomena, and are tracers that can set boundary conditions to heliospheric models in addition to plasma, magnetic field or other measurements like galactic cosmic rays. 

This talk highlights (1) the synergies between the heliospheric and dust science, (2) the dust model predictions and (3) measurement requirements for dust measurements with an Interstellar Probe in different regions inside and outside of the heliosphere. We discuss how the choice of trajectories and launch date can affect the measurements and the science goals. 

Answering pressing questions concerning the dust-heliosphere interactions requires a multi-mission approach with missions inside the solar system as well. We therefore present interstellar dust impact predictions for the Destiny+ mission, and we illustrate how we aim to infer information about the heliosheath filtering using the data and simulations. 

Finally, we conclude - and highlight with some examples - why heliospheric/plasma physics and dust science go hand in hand, in particular for future mission proposals. We illustrate this with specific examples like the DOLPHIN and SunCHASER mission concepts and an instrument on the Lunar Gateway. 

How to cite: Sterken, V. J., Hunziker, S., Dialynas, K., Baalmann, L. R., Péronne, A., Krüger, H., Strub, P., Cho, K.-S., Carpenter, J. D., Posner, A., and Brandt, P.: Heliospheric and cosmic dust science with Interstellar Probe and with missions inside the solar system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20141, https://doi.org/10.5194/egusphere-egu24-20141, 2024.

EGU24-20405 | ECS | Orals | ST1.14

MHD simulations of meso-scale processes in an ICME-like Magnetic Flux Rope 

Mattia Sangalli, Andrea Verdini, Simone Landi, and Emanuele Papini

Coronal Mass Ejections (CMEs) are among the main drivers of geomagnetic storms. 
The intensity of such storms is related to both the amplitude, coherence
and orientation of the magnetic field embedded in the magnetic cloud carried by
the CME, which can be often identified as a Magnetic Flux Rope (MFR).

During their propagation in the Heliosphere, MFRs are subject
to meso/small-scale processes such as magnetic reconnection and interaction with
turbulent fluctuations. The latter arise from solar wind turbulence,
but also include the turbulent sheath region which can form behind the
interplanetary shock driven by the CME.
These processes are difficult to capture in global numerical simulations of
CMEs and are possibly responsible for the rather small magnetic
correlation lengths which have been estimated for magnetic clouds, as short as a few tenth of AU.

We present a new numerical approach that exploits a lagrangian reference frame
to follow the evolution of a MFR via a high-resolution, 2.5D, visco-resistive 
MHD code implementing spherical expansion (Expanding Box Model).
In particular, we simulate the evolution of a low-beta MFR immersed in a
turbulent medium and study the resiliency of the magnetic structure as a
function of the amplitude and correlation length of the surrounding turbulence.
We present preliminary results using different proxies to estimate the evolution
of MFR coherence and helicity.

How to cite: Sangalli, M., Verdini, A., Landi, S., and Papini, E.: MHD simulations of meso-scale processes in an ICME-like Magnetic Flux Rope, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20405, https://doi.org/10.5194/egusphere-egu24-20405, 2024.

EGU24-20892 | Orals | ST1.14

Constraints on the Alfvénicity of switchbacks 

Oleksiy Agapitov, James Drake, Marc Swisdak, Kyung-Eun Choi, and Nour Raouafi

Switchbacks (SBs) are localized structures in the solar wind containing deflections of the magnetic field direction relative to the background solar wind magnetic field. The amplitudes of the magnetic field deflection angles (θ) for different SBs vary from ~40 to ~160-170 degrees. Alignment of the perturbations of the magnetic field (Δ\vec{B}) and the bulk solar wind velocity (\Delta \vec{V}) is observed inside SBs, so that \Delta\vec{V}~\Delta \vec{B} when the background magnetic field is directed toward the sun (if the background solar wind magnetic field direction is anti-sunward then \Delta\vec{V}~-\Delta\vec{B}, supporting anti-sunward propagation in the background solar wind frame). This causes spiky enhancements of the radial bulk velocity inside SBs. We have investigated the deviations of SB perturbations from Alfvénicity by evaluating the distribution of the parameter α, defined as the ratio of the parallel to Δ\vec{B} component of Δ\vec{V} to Δ\vec{V}_A=Δ\vec{B}/sqrt(4π n_i m_i) inside SBs, i.e. α=V_{}/Δ\vec{V}_A (α=Δ\vec{V}/Δ\vec{V}_A when Δ\vec{V}~-Δ\vec{B}), which quantifies the deviation of the perturbation from an Alfvénic one. Based on Parker Solar Probe (PSP) observations, we show that α inside SBs has systematically lower values than it has in the pristine solar wind: α inside SBs observed during PSP Encounter 1 were distributed in a range from ~0.2 to ~0.9 The upper limit on α is constrained by the requirement that the jump in velocity across the switchback boundary be less than the local Alfvén speed. This prevents the onset of shear flow instabilities. The consequence of this limitation is that the perturbation of the proton bulk velocity in SBs with θ>π/3 cannot reach α=1 (the Alfvénicity condition) and the highest possible alpha for an SB with θ=π is 0.5. These results have consequences for the interpretation of switchbacks as large amplitude Alfvén waves.

How to cite: Agapitov, O., Drake, J., Swisdak, M., Choi, K.-E., and Raouafi, N.: Constraints on the Alfvénicity of switchbacks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20892, https://doi.org/10.5194/egusphere-egu24-20892, 2024.

EGU24-1027 | ECS | Orals | PS3.1

Constraining the mass of meteoroids entering the atmosphere 

Simon Anghel, Mirel Birlan, and Dan-Alin Nedelcu

Cosmic objects, predominantly small meteoroids, frequently interact with Earth's atmosphere, and often go undetected due to their small size. Thus, to better understand the nature of these objects, we need to deploy networks of detectors which track their atmospheric disintegration [1]. This study delves into techniques for measuring the pre-atmospheric mass of meteoroids with known trajectories, some of which were the subject of successful meteorite recovery campaigns. Among the studied methods, we found that the radiated light of the meteoroid disintegration is the most reliable method of estimating its kinetic energy and pre-atmospheric mass [2]. This relation in combination with currently expanding fireball networks [3] can be used to calibrate other methods of estimating the objects mass (e.g. radio, infrasound). Ultimately, by constraining the size and frequency of small meteoroids, we can make inferences about the formation, evolution, and distribution of small objects and debris in the Solar System.

 

References:

[1] Colas F. et al. (2020) Astronomy & Astrophysics 644:A53.  [2] Anghel S. et al. (2021) Monthly Notices of the Royal Astronomical Society 508:571. [3] Vida D. et al. (2021) Monthly Notices of the Royal Astronomical Society 506:5046.

 

How to cite: Anghel, S., Birlan, M., and Nedelcu, D.-A.: Constraining the mass of meteoroids entering the atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1027, https://doi.org/10.5194/egusphere-egu24-1027, 2024.

EGU24-2629 | Posters on site | PS3.1

Highly collisional regions determined by interplanetary magnetic field structures 

Hairong Lai, Lin Pan, Yingdong Jia, Christopher Russell, Martin Connors, and Jun Cui

Submicron debris released in interplanetary collisions gets charged in the solar wind and generates disturbances to the magnetic field environment. The unique magnetic field disturbances, named interplanetary field enhancements (IFEs) are recorded by many spacecraft. In this study, we have developed a novel model to trace the IFEs to their origins. By employing this model, we can pinout regions with highly collision frequencies, thereby identifying regions of intense collisional activity. We can also determine the long-term variation of these highly collisional regions with interplanetary magnetic field observations over decades. The model can help constrain interplanetary magnetic disturbances and our results can be used to guide part of the interplanetary-object survey.

How to cite: Lai, H., Pan, L., Jia, Y., Russell, C., Connors, M., and Cui, J.: Highly collisional regions determined by interplanetary magnetic field structures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2629, https://doi.org/10.5194/egusphere-egu24-2629, 2024.

EGU24-2750 | ECS | Orals | PS3.1

The Mineralogy and Unique Widmanstatten Pattern in Iron Meteorites 

Salma Subhi and Aisha Alowais

This research aims to investigate iron meteorites samples, in terms of their elemental composition, distinguished structure, and their role in enhancing our understanding of the early solar system astrophysical processes. Iron meteorites represent a distinctive category of extraterrestrial materials, provide valuable insights into the formation and composition of asteroids, and the historical evolution of the early solar system around 4.6 billion years ago. Physical tests, including magnetism, fusion crust, density, and the window test, were performed on 140 samples from 2017 to 2023, with 161 analyses being carried out.  In addition to that, the study sheds light on the metallic phases of an oriented intergrowth of kamacite and taenite bands, revealing their occurrence in a unique Widmanstatten pattern. This pattern is visible on the studied samples that have been cut, polished, and etched with a weak, nitric acid. This remarkable pattern provides essential information for unraveling the thermal and cooling histories of these celestial bodies. Advanced analytical techniques such as X-ray fluorescence (XRF), and X-ray diffraction (XRD), were employed to identify the mineralogy and chemical composition of a diverse array of specimens. Iron-nickel minerals such as Kamacite are commonly found in the studied samples as well as the presence of troilite (FeS) inclusions, and traces of other elements. Of the 140 samples, three samples from different countries were identified as iron meteorites, allowing for a nuanced exploration of their unique characteristics. The chemical composition and mineralogy of the samples, revealed by the mentioned techniques, lead us to conclude that these samples formed at the core of asteroids or fragmented planets. This research contributes significantly to the UAE’s planetary science program and enriches meteoritic studies for university students and researchers in this field.

How to cite: Subhi, S. and Alowais, A.: The Mineralogy and Unique Widmanstatten Pattern in Iron Meteorites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2750, https://doi.org/10.5194/egusphere-egu24-2750, 2024.

EGU24-3147 | ECS | Orals | PS3.1

Unraveling the Origins of JFC-like Bodies: A Comparative Study of Comets and Meteoroids 

Patrick Shober, Jeremie Vaubaillon, Gonzalo Tancredi, Hadrien Devillepoix, Eleanor Sansom, Sophie Deam, Simon Anghel, Francois Colas, and Silvia Martino

Jupiter-family comets (JFCs) originate from the Kuiper belt and scattered disk, characterized by short orbital periods and frequent interactions with Jupiter. Their icy composition and a chaotic transition to the inner solar system result in short dynamic and physical lifetimes. These features make JFCs key subjects for understanding the migration of celestial bodies and possibly the delivery of organic materials to the early Earth. Numerous studies of fireballs have historically posited a substantial contribution of large objects from JFC orbits, suggesting a significant presence of cometary material in the near-Earth environment. However, this prevalent belief necessitates a thorough re-examination, as the physical evolution of comets and the mechanisms governing their disintegration remain subjects of debate. Understanding the population of meteoroids and comets is crucial for evaluating this population's physical breakdown and evolution. Current dust models suggest that fragmentation and disintegration of comets play a significant role in populating the zodiacal cloud. However, the larger centimeter-meter scale debris observed by fireball networks has been shown to resemble more asteroidal sources dynamically, indicating that comets might be breaking down directly only into dust-sized fragments. 

This study extends the scope of existing research by conducting a detailed analysis of both JFCs and comet-like fireball observations, aiming to elucidate the origins and dynamics of objects on JFC-like orbits across varying size scales. Utilizing extensive data from four major fireball networks (DFN, EFN, FRIPON, MORP) and ephemeris data of JFCs, the research comprises 646 fireball orbits and 661 JFCs. Methods include orbital stability analysis over 10,000 years, Lyapunov lifetime estimation, debiased NEO model source region estimation, meteorite fall identification, and meteor shower analysis.

The analysis reveals that most meteoroids on JFC-like orbits do not align dynamically with typical JFCs. Instead, they predominantly originate from stable orbits in the outer main asteroid belt, challenging the notion that centimeter-to-meter scale meteoroids on JFC-like orbits primarily derive from JFCs. Furthermore, a subset of 24 JFCs in near-Earth orbits displayed unexpected orbital stability, suggesting a presence of asteroidal interlopers from the outer main belt within the JFC population.

Our study demonstrates significant dynamical differences between kilometer-scale JFCs and smaller meteoroids. While the larger JFCs frequently encounter Jupiter and have dynamic, transient orbits, the smaller meteoroids detected by fireball networks originate primarily from stable orbits, indicating a predominant influence of asteroidal material from the outer main belt. This finding challenges conventional assumptions about the origins of JFC-like debris observed on Earth and highlights the complexity and diversity of the small-body environment in our solar system.

 

How to cite: Shober, P., Vaubaillon, J., Tancredi, G., Devillepoix, H., Sansom, E., Deam, S., Anghel, S., Colas, F., and Martino, S.: Unraveling the Origins of JFC-like Bodies: A Comparative Study of Comets and Meteoroids, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3147, https://doi.org/10.5194/egusphere-egu24-3147, 2024.

EGU24-3854 | ECS | Posters on site | PS3.1

Image-based small body shape modeling using the neural implicit method 

Hao Chen, Jürgen Oberst, Konrad Willner, Xuanyu Hu, Friedrich Damme, Ramona Ziese, and Philipp Gläser

One of the objectives of cameras on spacecraft for exploration of asteroids and comets is to perform shape modeling of the small bodies. Stereo-photogrammetry (SPG) and stereo-photoclinometry (SPC) stand out as the two main image-based methods for shape modeling, used in both previous and ongoing missions. In recent years, machine learning technology has experienced rapid development and demonstrated great promise for planetary topographic modeling. However, applications to small bodies have been limited so far. In this work, we present a neural implicit shape modeling method designed specifically for small body images characterized by rapid model convergence. We select 25143 Itokawa, explored by the Hayabusa mission, as a demonstration.  The method uses a sparse set of 52 images captured by the Asteroid Multi-band Imaging Camera (AMICA). The results are consistent with models previously produced using the SPC method in terms of overall size and shape. Also, our method can effectively capture fine-scale terrain features on the surface of Itokawa. This suggests that the neural implicit method can provide a new option and insight for the 3D reconstruction of small bodies.

How to cite: Chen, H., Oberst, J., Willner, K., Hu, X., Damme, F., Ziese, R., and Gläser, P.: Image-based small body shape modeling using the neural implicit method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3854, https://doi.org/10.5194/egusphere-egu24-3854, 2024.

EGU24-4652 | ECS | Orals | PS3.1

Discovery of Rubble-Pile Asteroid Dynamics through Sparse Symbolic Regression 

Iosto Fodde and Fabio Ferrari

Current evidence shows that most asteroids are rubble piles, which are defined to be aggregates of loosely consolidated material bound by gravity and likely a small amount of cohesive strength. Rubble-pile asteroids are granular systems, which can be reshaped through external excitation like meteoritic impacts, the YORP effect, and planetary encounters. Universal modelling of granular systems is one of the major unsolved topics in physics, as these systems are chaotic, multi-scale, and highly dependent on the non-linear interactions between its constituent particles. These difficulties are exacerbated as the low gravity invalidates some terrestrial observations and scaling laws.

Most analytical models are based on continuum mechanics, like the Mohr-Coulomb or Drucker–Prager criterion, fitted to specific sets of observations. These models are able to explain certain aspects of the asteroid population well, but are not able to accurately describe all their critical properties and are furthermore not dynamical. On the other hand, numerical simulations have shown a great potential to predict the evolution of these systems, down to properties of their individual fragments. However, their high computational burden and sensitive dependency on initial conditions make it harder to generalise conclusions made from them.

This work tries to bridge the gap between numerical and analytical modelling of rubble pile asteroids, by using the data produced by numerical simulations to derive a set of analytical equations of motion. Machine learning based system identification methods like genetic programming or neural networks have been shown to work well in predicting complex non-linear dynamical systems. However, key properties of good analytical models, like interpretability and generalizability, are often neglected by these methods. For this reason the sparse identification of non-linear dynamics (SINDy) method was developed, which avoids this problem by applying a sequential thresholding least-squares algorithm on a set of mathematical functions to obtain a sparse representation of the dynamics. 

In this work, first a set of time series data is obtained from the numerical code GRAINS, which is an N-body code that takes into account the complex shape of the individual particles, as they interact through self gravity and contact. A set of macroscopic state and environment variables are selected, which can either be physical values like the moments of inertia and/or spin-up rate, or numerically derived optimal coordinates (using e.g. proper orthogonal decomposition). This time series data is then used by SINDy to obtain a symbolic representation of the time derivative of the state variables. The thresholding parameter of SINDy can be tuned to obtain either a simpler model that mainly qualitatively describes the system, or a more complex model that also has a good quantitative performance. These analytical models are then used to obtain various dynamical properties of the systems, e.g. equilibrium points, bifurcations, etc.

This research shows how the data obtained from simulations can be used to obtain a parsimonious model for the dynamics of rubble pile asteroids. These models can further improve our understanding of the origin and evolution of rubble-pile asteroids, and help inform and interpret future observations.

How to cite: Fodde, I. and Ferrari, F.: Discovery of Rubble-Pile Asteroid Dynamics through Sparse Symbolic Regression, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4652, https://doi.org/10.5194/egusphere-egu24-4652, 2024.

EGU24-6055 | ECS | Posters on site | PS3.1

Searching for a concentration of olivine-rich bodies in asteroid collisional families in the main belt 

Marjorie Galinier, Marco Delbo, Chrysa Avdellidou, and Laurent Galluccio

It is understood that large asteroids that were (partially) melted by the heat produced by the decay of radioactive elements at the beginning of our Solar System, differentiated into layers of distinct compositions: an iron core, an olivine-rich mantle and a basaltic crust (Šrámek et al. 2012; Kruijer et al. 2014; Elkins-Tanton & Weiss 2017). Traces of material corresponding to each of these layers have been identified by studying the composition of asteroids in the current main asteroid belt. In addition, the collisional break-up of a differentiated asteroid is expected to produce fragments of different compositions representative of each layer. However, no family with a clear abundance of olivine-rich mantle-like asteroids has been found to date (DeMeo et al. 2019). There is a scarcity of olivine-rich asteroids in the main belt compared to other compositions, known as the ’missing mantle problem’. DeMeo et al. (2019) states that, up to now, there is no statistical concentration of olivine-rich objects in any asteroid family, and that these objects are evenly distributed throughout the main belt.

Using the Gaia DR3 dataset, which contains more than 60 000 Solar System small bodies with reflectance spectra in the visible wavelength range (Gaia Collaboration et al. 2023), we analysed the collisional families of Nesvorny et al. (2015) to search for a potential concentration of olivine-rich asteroids in any family. This composition corresponds to the A-type spectroscopic class in several taxonomic schemes (Bus & Binzel 2002; DeMeo et al. 2009; Mahlke et al. 2022). We found from the study of literature data that the family (36256) 1999 XT17 (FIN 629 in Nesvorny et al. 2015) was the most probable to show a concentration of potential olivine-rich objects. This family is located in the ’pristine zone’ of the main belt (Brož et al. 2013), and it contains 58 members in Nesvorny et al. (2015), 15 of which show a spectrum in the Gaia DR3 dataset.

We classified these 15 members with a χ2 procedure, using a combination of their Gaia DR3 spectra and their literature data, when available. We used the Bus-DeMeo (DeMeo et al. 2009) taxonomic templates to perform this classification, following the methods of Avdellidou et al. (2022). We obtained 12 objects classified as A-types out of the 15. We analysed the spectra of these objects and their position in the proper orbital elements space, and we concluded that a cluster of objects within the collisional (36256) 1999 XT17 family might show homogeneous olivine-rich compositions. This cluster could have once been part of a completely or partially-differentiated body, or could have been formed from nebular processes.

We will present the implications of our findings, including the possibility that despite being rare, A-type asteroids might be better revealed by large-scale spectroscopic surveys, such as ESA Gaia DR3/DR4 and the future NASA’s SPHEREx mission.

How to cite: Galinier, M., Delbo, M., Avdellidou, C., and Galluccio, L.: Searching for a concentration of olivine-rich bodies in asteroid collisional families in the main belt, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6055, https://doi.org/10.5194/egusphere-egu24-6055, 2024.

EGU24-7979 | Posters on site | PS3.1

VNIR Spectral comparison between S-Type asteroids and brachinites and ungrouped brachinites-like, in support of the HERA mission 

Alessandra Migliorini, Cristian Carli, Enrico Bruschini, Tiberio Cuppone, Stefania Stefani, Giovanni Pratesi, Alice Stephan, Fiorangela La Forgia, and Monica Lazzarin

The Didymos-Dimorphos binary system, target of the DART mission that successfully impacted the small moon Dimorphos in September 2022, is classified as an S-type asteroid. It shows spectral properties that well fit with the regions that are closer to high olivine abundances in the Band Area Ratio (B.A.R.) versus Band Center at 1 μm (BCI) plane. Further investigation of the Didymos-Dimorphos system will be performed with the HERA mission, to be launched in October 2024. S-type asteroids are characterized by spectral properties that span from low-Ca pyroxene, up to high-Ca pyroxene and olivine content, with possible different abundances of those phases. Different potential types of meteorites can overlap this region as suggested in different works. High interest is generally attributed to those objects with spectral properties that are in between pyroxene and olivine composition to better understand the potential detection limit of olivine and so clarify the olivine-paradox. Here, we investigate the spectral properties of 12 brachinites and ungrouped achondrites brachinite-like (UBAs), that have olivine abundance between 57% and 94% (and fayalite, Fa, between 17.5% and 34%) with some minor variation in mineral association, abundance, and composition. We study the Visible to Near Infrared (VNIR) reflectance properties to evidence how they change in a spectral range suitable to investigate S-types and compare with Didymos spectral properties. In the VNIR spectral range these samples clearly show a systematic trend between the BCI and the B.A.R. that correlate with the olivine abundance and slightly with iron content on olivine. In fact, meteorites with high olivine amounts but a very low Fa content (i.e. low iron) have positions of the absorptions coherent with the associated pyroxene. Clearly the samples investigated in this work moved from the portion of S (III) type with higher BCI up to the region defined by the S (I) type as defined by Gaffey et al. (1993), with VNIR mainly dominated by olivine. We can notice how Didymos nicely fit within this domain defined by brachinites-UBAs and it is slightly out from the OC boot defined by the S (IV) type.

This research was supported by ASI-INAF n.2018-16-HH.0 (Ol-BODIES project) and by ASI (agreement n. 2022-8-HH.0) for ESA’s Hera mission.

How to cite: Migliorini, A., Carli, C., Bruschini, E., Cuppone, T., Stefani, S., Pratesi, G., Stephan, A., La Forgia, F., and Lazzarin, M.: VNIR Spectral comparison between S-Type asteroids and brachinites and ungrouped brachinites-like, in support of the HERA mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7979, https://doi.org/10.5194/egusphere-egu24-7979, 2024.

EGU24-8518 | Orals | PS3.1

Continuous monitoring of dust impacts across the inner heliosphere by the Solar Orbiter RPW/TDS Maximum Amplitudes 

David Píša, Jan Souček, Samuel Kočiščák, Andreas Kvammen, Jakub Vaverka, Tomáš Formánek, Ondřej Santolík, Michiko Morooka, Milan Maksimovic, and Arnaud Zaslavsky

Hypervelocity (>1 km/s) dust grains orbiting in the inner heliosphere can collide with a spacecraft and create a plasma cloud that changes electrical conditions in the surrounding plasma. These changes can be detected by the onboard radio and plasma wave receivers acting as efficient dust impact detectors. Estimated dust impact rates depend on the observation time window and they are commonly extrapolated. Our study presents the RPW/TDS Maximum Amplitudes (MAMP) data that continuously monitors signals from up to four RPW antenna configurations (monopole or dipole, and HF Search Coil) onboard the Solar Orbiter satellite. The signal is sampled in the high cadence (2.091 Msps) and stored in a buffer as the absolute maximum amplitude. MAMP values are then provided with a cadence between 32 and 128 sps, giving us a time resolution between 8 and 31 ms. Individual dust impacts detected by the onboard algorithm evaluating 62ms-long waveform snapshots every second are compared with the MAMP observations and show a very good match. After corrections for the high amplitude plasma waves or non-standard operational modes, and together with the TDS Statistics, the MAMP observations are used for the individual dust impact identification and corrected impact rates during the entire Solar Orbiter mission.

How to cite: Píša, D., Souček, J., Kočiščák, S., Kvammen, A., Vaverka, J., Formánek, T., Santolík, O., Morooka, M., Maksimovic, M., and Zaslavsky, A.: Continuous monitoring of dust impacts across the inner heliosphere by the Solar Orbiter RPW/TDS Maximum Amplitudes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8518, https://doi.org/10.5194/egusphere-egu24-8518, 2024.

EGU24-8629 | ECS | Posters on site | PS3.1

Laboratory reflectance spectra of enstatite and oldhamite mixtures for comparison with Earth-based reflectance spectra of asteroid 2867 Šteins 

Kathrin Markus, Gabriele Arnold, Lyuba Moroz, Daniela Henckel, and Harald Hiesinger

2867 Šteins is a main belt asteroid and was a fly-by target of ESA’s Rosetta mission [1]. It has been previously studied by ground-based observations (e.g., [2,3,4,5,6,7]). It has been classified as an E[II]-type asteroid. E-type asteroids are characterized by flat or slightly reddish and featureless reflectance spectra in the VIS and NIR and high geometric albedos and are generally associated with aubrites, enstatite achondrites [8]. E[II]-type asteroids additionally show an absorption band at 0.49 µm, which has been attributed to oldhamite [9]. The depth of the absorption band at 0.49 µm in Šteins’ spectra has been reported to be 9-13 % [3,5,6,7]. Oldhamite usually only occurs as an accessory phase while the abundance required to produce the absorption band is much higher.

We present 0.3 to 16 µm reflectance spectra of synthetic enstatite (Mg2Si2O6), synthetic oldhamite (CaS), and of their mixtures for comparison with spectra of E[II]-type asteroids such as Šteins, and investigate the spectral behavior of the mixtures with respect to their oldhamite content.

All reflectance spectra were collected using a Bruker Vertex 80v FTIR spectrometer at the Planetary Spectroscopy Laboratory (PSL) of the Institute of Planetary Research at DLR, Berlin [10]. The synthesis of the enstatite sample with the composition En99.6Fs0.0Wo0.4 has been described in [11]. The oldhamite sample was purchased from abcr GmbH. Mixtures containing 1, 3, 5, 10, 20, 30, 40, 50, 60, 70, 80, and 90 vol% oldhamite were prepared.

The spectrum of synthetic oldhamite shows an absorption band at 0.41 µm with a relative depth of 11.4 % instead of the absorption band at 0.49 µm. This band is visible in the spectra of all mixtures, even in the spectrum of the mixture with only 1 vol% oldhamite. In the MIR, the spectra with ≤10 vol% oldhamite are very similar to the spectrum of the pure enstatite and are generally dominated by the Christiansen feature and the Reststrahlen bands. The pure oldhamite is significantly brighter than the enstatite spectrum in the MIR. Changes in the band depth and reflectance do not occur as a single trend, but follow two distinct trends. One for mixtures with ≤10 vol% of oldhamite where changes occur rapidly and another trend for mixtures with ≥20 vol% of oldhamite where changes occur more slowly.

The differences in the oldhamite absorption band do not allow for an estimation of the oldhamite content on Šteins but an overall comparison between the laboratory spectra and Earth-based spectra of Šteins gives an upper limit for the oldhamite content on the surface of Šteins of 40 vol%. 

[1] Keller et al. (2010) Science, 327, 190-193. [2] Barucci et al. (2005) A&A, 430, 313-317. [3] Nedelcu et al. (2007) A&A, 473, L33-L36. [4] Dotto et al. (2009) A&A, 494, L29-L32. [5] Fornasier et al.  2007) A&A, 474, L29-L32. [6] Fornasier et al. (2008) Icarus 196, 119-134. [7] Weissman et al. (2008) Met. Planet. Sci., 43, 905-914. [8] Gaffey et al.  1993) Meteoritics 28, 161-187. [9] Burbine et al. (2002) Met. Planet. Sci., 37, 1233-1244. [10] Maturilli and Helbert. (2019) LPSC, 1846. [11] Markus et al. (2018) Planet. Space Sci., 159, 43-55.

How to cite: Markus, K., Arnold, G., Moroz, L., Henckel, D., and Hiesinger, H.: Laboratory reflectance spectra of enstatite and oldhamite mixtures for comparison with Earth-based reflectance spectra of asteroid 2867 Šteins, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8629, https://doi.org/10.5194/egusphere-egu24-8629, 2024.

3D models of asteroids provide their physical properties, such as shape, size, and surface features, which are of great importance to asteroid exploration missions and scientific research. The stereo photoclinometry (SPC) technique retrieves detailed surface topography of asteroids based on the reflectance information embedded in the image intensity of each pixel, thus the assessment of its performance is essential before the launch of the mission spacecraft. This work presents a laboratory experiment to evaluate the high-resolution and high-precision 3D surface models of asteroids reconstructed through an integrated photogrammetric and photoclinometric approach using simulation images. The whole experiment involves 3 steps. Firstly, construct the scaled-down experimental fields to simulate real in-situ conditions of the space probe with 3D printed models of asteroids, which represent the target asteroids of future missions. Then, collect simulation data according to various scenarios that might be encountered in a real on-orbit mission. Finally, reconstruct detailed asteroid models through the SPC refinement approach on the basis of stereo photogrammetry (SPG) models. Our previous studies indicate that SPC performance is influenced by both the azimuth and the incidence angles of illumination, as well as the image's general intensity. The experiment takes all these factors into account, as a reference for improving the image-acquiring plan during the in-situ detailed survey phase. The integrated approach will be tested for pixel-wise surface reconstruction of 3D-printed asteroid models of different shapes, i.e., Itokawa and Bennu. According to initial experimental results, the developed approach demonstrates the capability to attain high geometric accuracies and capture fine small-scale topographic details, which fulfills the requirement of the asteroid exploration missions.

How to cite: Li, H., Wu, B., and Liu, Y.: Detailed 3D Surface Reconstruction of Asteroids by Integrating Stereo Photogrammetry and Stereo Photoclinometry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8725, https://doi.org/10.5194/egusphere-egu24-8725, 2024.

EGU24-8902 | ECS | Posters on site | PS3.1

Laboratory study of dust impact ion free expansion 

Libor Nouzak, John Fontanese, Kathryn R. Edwards, Mihaly Horanyi, and Zoltan Sternovsky

This study presents the investigation of the angular and velocity distribution of ions expanding freely from a dust impact generated plasma plume. The characteristic angular and velocity distributions are relevant for the design of dust detector and analyzer instrument, or for the interpretation of electric field antenna signals generated by dust impacts on the spacecraft body.  Iron dust particles of micron and sub-micron size are accelerated to velocities 2–40 km/s using the electrostatic dust accelerator operated at the University of Colorado. A unique experimental setup with a delay line detector (DLD) is used to measure the properties of the expanding ion cloud. The DLD provides the position and the time of impact for individual ions originating from the tungsten impact plate. The angular distribution of ions with respect to target normal is calculated from these positions. The velocity distribution is determined from arrival times of the ions on the detector. The experimental results show that the impact-generated ions expand in the form of a plume with angular distribution following a cosine law and half angle 25°. The velocity distribution consists from different parts which correspond to expansion of a distinct plasma components. The slowest component of the distribution has the most probably speed around 5 km/s and the fastest component around 30 km/s. The contribution of the components changes according to velocity of dust.

How to cite: Nouzak, L., Fontanese, J., Edwards, K. R., Horanyi, M., and Sternovsky, Z.: Laboratory study of dust impact ion free expansion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8902, https://doi.org/10.5194/egusphere-egu24-8902, 2024.

EGU24-9078 | Posters on site | PS3.1

On the question of when to settle for a target in the Comet Interceptor mission 

Erik Vigren, Anders I. Eriksson, Niklas J. T. Edberg, and Colin Snodgrass

The Comet Interceptor (CI) mission, planned for launch in 2029, will ideally involve a flyby of a dynamically new long period comet or an interstellar object passing through the inner solar system. Powerful ground based facilities like the Vera C. Rubin Observatory Legacy Survey of Space and Time will aid in the search for a potential target. The CI mission includes a parking phase at the Sun-Earth L2 point and the target may in fact still be unknown by the time of launch. The question on when to settle for a target is complex. For instance may arise the question of how long time it is motivated to await with a final decision given the chance that a better target may show up if just waiting a little bit longer. We present expectation value-based formalism that could aid in decision making of such kind.

How to cite: Vigren, E., Eriksson, A. I., Edberg, N. J. T., and Snodgrass, C.: On the question of when to settle for a target in the Comet Interceptor mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9078, https://doi.org/10.5194/egusphere-egu24-9078, 2024.

EGU24-9663 | ECS | Posters on site | PS3.1

Massive Micron Meteoroids in the near-Sun Space as Observed by Parker Solar Probe 

Tianhang Chen, Jiansen He, Ziqi Wu, and Rui Zhuo

The interplanetary dust, together with solar wind plasma, forms the space environment of the inner heliosphere. There are two main particle populations of dust, α-meteoroids in bound orbits with micron size and β-meteoroids in hyperbolic orbits with sub-micron and nano size. Collisions between dust particles and dynamical evolution of their orbits greatly shape the grain size and heliocentric distance distributions of dust cloud, yet the specific mechanism still remains unknown. After Parker Solar Probe (PSP) successfully performed more than 10 encounter missions, plenty of dust impact events have been recognized, providing a glimpse of the complex. In this work, we analyze the geometry feature of streaks captured by the Wide-field Imager for Parker Solar Probe (WISPR) and try to locate the impact origins. In addition, we translate the results of streak storms in WISPR images to dust impact rates so as to compare with those recorded by the PSP FIELDS Experiment (FIELDS). We find there is evidence for the α-meteoroids impact. The debris products are directly observed by WISPR. We also find that the dust impact rates determined by the two methods are in good agreement. A pure α-meteoroid model is used to fit the observed impact rates within about 0.3 AU (~67 solar radii) and the fit is pretty well, especially for the rates near perihelion of PSP. Based on these results, we suggest that α-meteoroids can take a significant proportion of zodiacal dust near the Sun and this may lead to a different size distribution of dust cloud and a different mechanism of meteoritic evolution from what they are observed as at 1 AU.

How to cite: Chen, T., He, J., Wu, Z., and Zhuo, R.: Massive Micron Meteoroids in the near-Sun Space as Observed by Parker Solar Probe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9663, https://doi.org/10.5194/egusphere-egu24-9663, 2024.

EGU24-9846 | ECS | Orals | PS3.1

Planar dynamics of non-spherical close tidally locked binaries asteroids  

Gabriel Caritá, Hauke Hussmann, Antonio Fernando Bertachini de Almeida Prado, Nelson Callegari, Maria Helena Moreira Morais, and Ricardo Egydio de Carvalho

Asteroids are originated by the evolution of the disk in the Solar System and, in general, do not have spherical and symmetrical shapes. The reason for those irregular shapes is the small mass of the bodies, such that gravity is not sufficient to make them reach a spherical shape. Those irregular shapes make the study of spacecraft orbits to investigate those objects  complex. Adding this to the fact that their weak gravitational field allows forces that are usually negligible or of second order  for spacecraft near a massive body (e.g.,  solar radiation pressure) to be comparable to the gravitational forces, provides an interesting and important problem to be studied in terms of astrodynamics. The study of asteroids is important because they carry essential scientific information about the origin and evolution of the Solar System. For all these points, it is important to understand their motion and investigate the motion of a spacecraft close to the asteroid. Asteroids may exist alone or in groups of two or three. Recent observations show that binary asteroids could be even more common than we think. In that sense, the present research focused on studying the orbital evolution of a binary asteroid system with almost equal masses composed of two non-spherical asteroids tidally locked that are close to each other, and the dynamical evolution of spacecraft orbiting the system. Since Keplerian orbital elements are not always a good approach for spacecraft in high mass ratio binary systems, to study this problem, we consider the mathematical models of the planar full two-body-problem for the binary asteroid, and the circular restricted three-body problem for the spacecraft, adding ellipsoidal geometry to represent the non-spherical shapes of the binary in order to find natural stable solutions. We also analyzed the structure of the phase space and the importance of the effect of solar radiation pressure on this dynamics. We studied the dynamics and the effect of the gravitational shape of close binary systems in their mutual orbits, as well as the existence of spacecraft circular and resonant orbits. As an application of this research, we studied the binary system Antiope 90. We found stable, close direct and retrograde orbits for the jacobi constants between -1.1 and -0.5; and internal resonant retrograde orbits within the primary and the secondary for the energy -0.7. The majority of the dynamical structure has survived over 90 days assuming the effects of solar pressure radiation.

How to cite: Caritá, G., Hussmann, H., Prado, A. F. B. D. A., Callegari, N., Morais, M. H. M., and de Carvalho, R. E.: Planar dynamics of non-spherical close tidally locked binaries asteroids , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9846, https://doi.org/10.5194/egusphere-egu24-9846, 2024.

EGU24-10569 | Posters on site | PS3.1

Influence of ambient environment on dust grains detection by electric field instruments 

Jakub Vaverka, Jiří Pavlů, Jana Šafránková, Zdeněk Němeček, and Samia Ijaz

Dust grain impacting the spacecraft body can be either partly or totally evaporated and ionized as well as a small part of spacecraft material. A cloud of charged particles (impact cloud) generated by such impact can consequently influence the spacecraft potential and/or measurements of on-board scientific instruments. Electric field instruments are sensitive to these disturbances and typically register signals generated by dust impacts as short transient pulses. This method is commonly used for the detection of dust grains even without dedicated dust detectors.

The presented study is focused on the influence of the ambient environment on dust detection for various designs of electric field instruments (probes/antennas) operating in the monopole and dipole configurations. An ambient plasma influences the spacecraft potential, which is crucial for charge separation and consequent propagation of the impact cloud. The plasma and solitary waves also affect dust detection by the presence of other pulses in the measured data. It is important to understand these effects to compare results obtained by various spacecraft in different environments.

How to cite: Vaverka, J., Pavlů, J., Šafránková, J., Němeček, Z., and Ijaz, S.: Influence of ambient environment on dust grains detection by electric field instruments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10569, https://doi.org/10.5194/egusphere-egu24-10569, 2024.

EGU24-10656 | ECS | Posters on site | PS3.1

Study of Dust Impact Signals around Mars using MAVEN/LPW Observations 

Samia Ijaz, Jakub Vaverka, Zdeněk Němeček, and Jana Šafránková

Electric field instruments can detect dust impacts on a spacecraft body as transient pulses in the measured electric field. Our study investigates these transient (millisecond) pulses detected by the Langmuir Probe and Waves (LPW) instrument onboard the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. We present a statistical analysis of 360,000 medium frequency burst electric field waveforms recorded in 2015; the study aims to identify and analyze the characteristics of these transient pulses. An automatic routine is used to detect waveforms with rapid fluctuations in the electric field data; this comprises over 12,000 events in the dipole and nearly 5,000 in the monopole configurations. Our findings reveal that most of the pulses in monopole configuration are likely the result of interference rather than dust impacts. Our analysis mainly focuses on dipole observations, which predominantly consist of bipolar events typically associated with dust impacts. These events are mainly detected in the Martian ionosphere, where the spacecraft is negatively charged. Fewer events are recorded when the spacecraft is positively charged, with a maximum at an altitude of 1200 km. The low detection rate of dust impact signals outside the ionosphere suggests that the planet is the most probable source of these dust particles. However, the physical processes by which dust grains are lifted from the surface of the planet to high altitudes are not clear, and thus a possibility that the signals observed might not be generated by dust impacts remains for further investigations.

How to cite: Ijaz, S., Vaverka, J., Němeček, Z., and Šafránková, J.: Study of Dust Impact Signals around Mars using MAVEN/LPW Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10656, https://doi.org/10.5194/egusphere-egu24-10656, 2024.

EGU24-11065 | ECS | Orals | PS3.1

Spectral ratioing of Afρ to constrain the particle size distributions of comets 

Nico Haslebacher, Nicolas Thomas, and Raphael Marschall

Introduction: Afρ is a measure for the brightness of a cometary coma [1]. In the past, Afρ has been commonly used as a proxy for the activity of comets [2]. In later studies it was found that the brightness of a coma (Afρ) is dominated by the particle size distribution [3] and that Afρ on its own is a poor predictor for the activity of a comet [4]. In this work we use a numerical model of cometary dust environments to get a better understanding of the relationship of Afρ and the particle size distribution and show how spectral ratioing of Afρ could provide constraints for the particle size distributions of comets.

Methods: A numerical dust model is used to calculate the expected Afρ at two different wavelengths for a wide range of different parameters. Specifically, we calculate the ratio Afρ (425 nm) / Afρ (900 nm) in dependence to the power-law index of the particle size distribution. It is implicitly assumed that the particle size distribution follows a simple power-law. We use particles sizes in the range of 0.01 µm to 10 cm and choose  logarithmic particle size bins that are small enough to have a converging result. The scattering properties of each particle size are calculated for three different dust compositions. We use water ice to model bright particles, enstatite to model silicate particles and amorphous carbon to model dark particles. The scattering properties are calculated based on Mie-theory. Further, we studied day-night asymmetries, parameters related to the outflow velocity of the dust and phase angle effects.

Results: We show that the spectral ratio of Afρ modelled at 425 nm and 900 nm correlate with the power-law index of the particle size distribution. Large particle dominated comas can be distinguished from small particle dominated comas. For small particle dominated coma the specral ratio of Afρ can be used to further constrain the power-law index.

Acknowledgments: This work has been carried out within the framework of the National Centre of Competence in Research PlanetS supported by the Swiss National Science Foundation under grants 51NF40_182901 and 51NF40_205606. Additional financial support from the European Space Agency is also acknowledged.

References: [1] A’Hearn, M. F. et. al. (1984), AJ, 89, 579 [2] Weiler, M. et. Al. (2003), A&A, 403, 313 [3] Fink, U. and Rubin, M. (2012), Icarus, 221, 721 [4] Marschall, R. et. al. (2022), A&A, 666, A151

 

How to cite: Haslebacher, N., Thomas, N., and Marschall, R.: Spectral ratioing of Afρ to constrain the particle size distributions of comets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11065, https://doi.org/10.5194/egusphere-egu24-11065, 2024.

An increasing number of small extraterrestrial objects in the Solar System are found to have bilobed shapes, which could have resulted from the merger of two independently formed bodies. It is both natural and justified to treat the lobes separately to account for, or discern, any potential difference between them (Andert, et al., 2015). Gravity provides a crucial constraint on the interior mass distribution of the body and is among the key scientific objectives in most space missions. Most often, the gravitational field is modeled as a spherical harmonic (SH) series, whose coefficients are then used along with other constraints to interpret the interior structure.

In this study, a double harmonic-series approach for the bilobed bodies is presented. Namely, a harmonic series is established for each lobe to facilitate the investigation of their interior structures separately. The focus of the analysis is on comet 67P/Churyumov-Gerasimenko, the rendezvous target of the Rosetta mission with an exemplary bilobed shape and variable gravity field (Sierks et al. 2015; Pätzold et al. 2016, 2019). We employ the ellipsoidal harmonic (EH) series, whose coefficients are fully analogous to those of the SH and whose reference surfaces fit more closely the triaxial shapes of the individual lobes (Hu 2016).

We develop the double EH model for 67P via simulations and assess the model performance around the body. Additionally, we discuss the equivalence of the double EH model to the SH model as well as the conditions for direct model transformation from the latter. We revisit the physical meaning of the EH coefficients and demonstrate how their known relationship to the body's mass density moments can be leveraged to interpret different mass distributions of the comet. Importantly, there should be no restriction on the applicability of the method to other bilobed objects.

 

Reference

Andert, T., et al. (2015), The Gravity field of Comet 67 P/Churyumov-Gerasimenko Expressed in Bispherical Harmonics, in: AGU Fall Meeting Abstracts. pp. P31E-2109.

Hu, X. (2016), The exact transformation from spherical harmonic to ellipsoidal harmonic coefficients for gravitational field modeling, Celest. Mech. & Dyn. Ast. 125, pp. 195-222, https://doi.org/10.1007/s10569-016-9678-z.

Pätzold, M., et al. (2016), A homogeneous nucleus for comet 67P/Churyumov-Gerasimenko from its gravity field, Nature, vol. 530, pp. 63-65, https://doi.org/10.1038/nature16535.

Pätzold, M., et al. (2019), The Nucleus of comet 67P/Churyumov-Gerasimenko - Part I: The global view - nucleus mass, mass-loss, porosity, and implications. Monthly Notices of the Royal Astronomical Society, 483, 2337–2346, https://doi.org/10.1093/mnras/sty3171.

Sierks H., et al. (2015), On the nucleus structure and activity of comet 67P/Churyumov-Gerasimenko, Science, vol. 347, no. 6220, https://doi.org/10.1126/science.aaa1044.

How to cite: Hu, X. and Andert, T.: Double harmonic-series gravitational field model for bilobed small bodies: example for 67P/Churyumov-Gerasimenko, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12458, https://doi.org/10.5194/egusphere-egu24-12458, 2024.

EGU24-12996 | ECS | Posters on site | PS3.1

Simulating NASA DART impact: Insights into the interior of asteroid Dimorphos 

Cem Berk Senel, Ozgur Karatekin, Robert Luther, Grégoire Henry, and Philippe Claeys

Impacts are commonplace in our Solar System, constituting one of the key mechanisms that regulate the evolution of asteroids and comets. From small-scale Martian meteorites to large biosphere-forming collisions, e.g., the Chicxulub catastrophe at the end of the Cretaceous Period, impact events are essential to understanding the dynamic history of planetary bodies. In recent years, asteroid missions have made major advancements in characterizing the Near-Earth Objects (NEOs), from JAXA's Hayabusa2 sample-return mission on asteroid Ryugu to NASA’s recent DART space mission that performed the first kinetic deflection on asteroid Dimorphos [1]. The upcoming Hera mission by the European Space Agency (ESA) will characterize the DART impact during a rendezvous with Dimorphos in 2026. Meanwhile, numerical simulations have studied the potential impact cratering and ejecta plume outcomes in response to the DART-scale impactor [2]. Yet, interior features of near-Earth asteroids remain unknown. Understanding what lies inside Dimorphos, various interior scenarios are tested by combining shock physics modeling with the outputs of ejecta observations. The observed ejecta outcome makes it possible to groundtruth modeled ejecta. Therefore, a series of hypervelocity impact simulations are performed through the iSALE2D shock physics code [3-5], incorporating recent mechanical and material parameters [6,7]. Additionally, the DART spacecraft is approximated to be a porous aluminum sphere. The impactor vertically collides at a speed of 6.145 km/s, with Dimorphos taken as an axisymmetric ellipsoid. We test the DART impact within the low-to-intermediate strength regime (1 Pa - 1 kPa) with a wide porosity range (10 - 50%) for a homogeneous interior. This process is iterated for heterogeneous interiors consisting of multiple weak or strong inner layering with or without core formation and boulders. The model results provide new predictions for the plausible cratering formation, thus key insights into the interior of Dimorphos.
References
[1] Daly et al. (2023). Nature, 616(7957), 443-447.
[2] Stickle et al. (2022). The Planetary science journal, 3(11), 248.
[3] Amsden et al. (1980). LANL Report, LA-8095:101p., New Mexico.
[4] Collins et al. (2004). Meteoritics & Planetary Science, 39(2), 217-231.
[5]​​ Wünnemann et al. (2006). Icarus, 180(2), 514-527.
[6] Luther et al. (2022). The Planetary science journal, 3(10), 227.
[7] Raducan et al. (2022). The Planetary science journal, 3(6), 128.

How to cite: Senel, C. B., Karatekin, O., Luther, R., Henry, G., and Claeys, P.: Simulating NASA DART impact: Insights into the interior of asteroid Dimorphos, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12996, https://doi.org/10.5194/egusphere-egu24-12996, 2024.

EGU24-13303 | Orals | PS3.1

Space Weathering Provides a Lower Limit on the Age of Saturn’s Rings 

Larry W. Esposito, Joshua P. Elliott, and E. Todd Bradley

Cassini observations of the micrometeoroid bombardment flux, ring mass and fractional pollution constrain the origin and history of Saturn’s rings. In the simplest model, the age of the rings can be estimated by assuming the rings are a closed system with constant bombardment at the current rate. Observations during the Cassini Grand Finale orbits provide some challenges for this assumption. Further, the remote sensing of the rings shows a red slope, with higher pollution at the shortest wavelengths, consistent with reddening due to space weathering of atmosphereless bodies. If processes at the time of the micrometeorite impacts or subsequent chemical and physical weathering can degrade the original pollutants, this means that laboratory spectra are not appropriate to determine the total extrinsic material that has struck the rings over its lifetime. Rosetta data on the dust composition and surface reflectivity of Comet P67 provide our starting point for the composition of the bombarding material. Laboratory results for irradiation of icy outer solar system analogues indicate oxidation of organics and other pollutants over time. It is now generally agreed that the radiolysis of ice by energetic ions, electrons and solar UV photons produces the oxygen, ozone and peroxide seen at many icy satellites. The porosity of ice provides sufficient space for chemical reactions and mobility (Li 2022). The ring particle surfaces are in addition continually gardened by particle collisions and meteoritic impacts. Because of these loss processes, the current fractional pollution provides only a lower limit on the total integrated pollution flux, and thus a lower limit for the ring age. Two independent analyses of Cassini UVIS spectra of Saturn’s rings give fractional pollution in the outer B ring of 2-3%. This provides a lower limit of 400 to 1600 million years for the most opaque parts of Saturn’s B ring, depending on whether we use the maximum or minimum values for the bombardment rate reported by Cassini CDA (Kempf 2023). The A and C rings, as well as other ring structures, may be younger, having formed more recently.

How to cite: Esposito, L. W., Elliott, J. P., and Bradley, E. T.: Space Weathering Provides a Lower Limit on the Age of Saturn’s Rings, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13303, https://doi.org/10.5194/egusphere-egu24-13303, 2024.

EGU24-14995 | ECS | Orals | PS3.1

Advanced Meteorite Identification through YOLO Object Detection Algorithms 

Aisha Alowais, Munya Alkhalifa, Salma Subhi, and Ilias Fernini

This study addresses the challenge of visually identifying meteorites from terrestrial rocks, traditionally a task for experts followed by chemical analysis. We propose a transformative approach using computer vision and machine learning, employing YOLO (You Only Look Once) object detection algorithms (versions 5, 6, 7, and 8), to overcome the bottleneck in expert availability for instantaneous classification. Leveraging a curated selection from the Sharjah Academy for Astronomy, Space Sciences, and Technology (SAASST) unique meteorite collection, we aim to differentiate meteorites from terrestrial rocks based on their surface features and characteristics. The collection comprises a diverse assemblage of approximately 8,000 objects such as iron meteorites, Martian meteorites, tektites, fulgurites, and more. Our methodology includes a comparative analysis of YOLO versions, focusing on precision, recall, and F1 scores to assess each algorithm's adaptability to the unique features of meteoritic material. Preliminary results indicate YOLOv5 as the most efficient compared to its previous versions, achieving a maximum mAP of 0.995 and correctly classifying 93% of test samples. This study aims to determine the optimal YOLO version for enhancing the accuracy and efficiency of meteorite classification. In addition, the selected optimal model will be deployed on a Jetson Nano processor aboard a drone, significantly enhancing onsite meteorite detection capabilities.

How to cite: Alowais, A., Alkhalifa, M., Subhi, S., and Fernini, I.: Advanced Meteorite Identification through YOLO Object Detection Algorithms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14995, https://doi.org/10.5194/egusphere-egu24-14995, 2024.

EGU24-15462 | ECS | Posters on site | PS3.1

Lake Zapovednoe's Molten Fragments of Tunguska Airburst in 1908 

Lucie Smrčinová, Gunther Kletetschka, Richard Štorc, Eva Švecová, Viktor Goliáš, and Daniel Vondrák

The Tunguska airburst occurred on June 30, 1908 and it was most likely caused by the impact of the Tunguska cosmic body (TCB). It is not clear what the origin of the TCB was as no impact craters or possible body remains have been found to date. We studied the possible molten fragments of the TCB found in lacustine sediments of Zapovednoe Lake, a water body which is located ~60 km west from the airburst epicentre. Lake sediment cores which were retrieved from the lake contained an event layer dated to 1908–1910 CE. This layer included microscopical molten fragments and anomalous composition.

 

Three short cores (ZP1, ZP2, ZP3) were extracted in the central part of Zapovednoe Lake using a Kajak gravity corer. We used an X-ray fluorescence spectroscopy (XRF) and Scanning Electron Microscopy (SEM) for lake sediment characterization. Magnetic spherules (MSPs) and other magnetic grains were extracted from ZP1 by standard magnetic separation technique and all MSPs were identified with SEM and characterized using elemental microanalysis. We performed XRF analyses of 2 or 5 mm thick slices of the sediment cores and evaluated the concentrations and ratios of individual elements. Sediment samples of ZP2 were used for core dating, using gamma spectrometry for the specific activity of 210Pb, 137Cs, and 226Ra isotopes similar to the record from nearby Suzdalevo Lake.

 

Radioisotope activities revealed the age consistent with the year 1908 CE. The gamma spectrometry results were in good agreement with the XRF measurements, where the event layer had increased concentrations of lithogenic elements, such as Mg, Al, Si, S, K, Ca, Ti, Fe, Cu and Mn. The SEM analysis revealed that molten fragments were indeed found among the potential MSPs extracted from the event layer and adjacent layers. These spherical melts were rich in iron and most of them were found at depth corresponding to the event layer. Only a small portion of MSPs was found in the adjacent layers.

 

Our results revealed the presence of the TCB airburst event layer. The anomalous event layer resulted from increased erosion in the Zapovednoe Lake catchment. However, massive tree falls and subsequent wildfires from the airburst likely contributed to the anomalous elemental composition of the lake sediment as well. We found for the first time in lake sediments preserved MSPs which come from the melts produced by the TCB airburst and may contain an extraterrestrial material.

How to cite: Smrčinová, L., Kletetschka, G., Štorc, R., Švecová, E., Goliáš, V., and Vondrák, D.: Lake Zapovednoe's Molten Fragments of Tunguska Airburst in 1908, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15462, https://doi.org/10.5194/egusphere-egu24-15462, 2024.

EGU24-15528 | Posters on site | PS3.1

The influence of sputtering and sublimation on Kuiper belt dust trajectories 

Ingrid Mann, Andrew Poppe, Amalie Gjelsvik, and Aigen Li

NASA’s New Horizons spacecraft is currently exploring the outer solar system and passes the Kuiper Belt. The Student Dust Counter (SDC) onboard New Horizons has measured the flux of interplanetary dust grains throughout nearly the entire mission so far. The observed dust flux around 50 AU at the expected edge of the the Kuipe belt is higher than predicted. A possible explanation could lie in the trajetcries of the dust particles that can be pushed out to large distances by radiation pressure force. We investigate the trajectories of ice particles in the Kuiper belt which are more strongly influenced by radiation pressure when their sizes are reduced, due to mass loss caused by sublimation, solar wind sputtering and photo sputtering. The results suggest that the changing size of the particles may lead to a more stable and confined dust ring in the Solar System's Kuiper Belt. 

How to cite: Mann, I., Poppe, A., Gjelsvik, A., and Li, A.: The influence of sputtering and sublimation on Kuiper belt dust trajectories, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15528, https://doi.org/10.5194/egusphere-egu24-15528, 2024.

EGU24-15837 | ECS | Orals | PS3.1

Studying gas flow on cometary surfaces with diffusivity variations using flow simulations and experiments 

Stephan Zivithal, Günter Kargl, Wolfgang Macher, Carsten Güttler, Bastian Gundlach, Holger Sierks, and Jürgen Blum

Comet surfaces have a complex morphology on large scales (such as pits, depressions, scarps and faults) as well as on small scales (such as particle size, porosity distribution and roughness of the comet surface). Little is known about the influence especially of small-scale structures on the gas-flow and the ability to lift off dust particles. Focusing on small-scale structures, we simulate diffusion processes applying Fick's law. For the upper and lower boundary of the simulated box, a flat sublimation front with constant pressure below the inactive surface layer and a perfect vacuum on the surface is assumed. By applying periodic boundary conditions in the planar direction, we mimic an infinite surface with periodic inhomogeneity. We performed the simulation with different variations of diffusivity. In one example, the simulation shows that a region of high porosity within a region of low porosity experiences an increase in the flow rate, as would be expected according to Fick's Law. Nevertheless, it also significantly changes the flow rate in the surrounding region due to lateral flows in the vicinity of the high diffusivity region. We analyze the results qualitatively and compare them with 3D Monte Carlo simulations in a similar setting, which shows a general agreement.

In addition, we conduct experiments with a dedicated vacuum-chamber to measure the viscous permeability and Knudsen diffusion of granular materials by applying the binary friction model. The design allows measurements in different gas-flow regimes, with most samples mainly covering the free molecular flow and the transition region. In the last measurement campaign, bi-disperse samples of spherical particles were measured and the results show a good agreement with generalized models depending on the specific surface area of the sample. The current measurement campaign focuses on angular materials and the influence of shape properties on diffusivity. The results show that packings of highly porous hollow cylinders have a lower diffusivity than expected compared to more compact packings of spherical particles. A comparison with Monte Carlo simulations (from [1,2]) of packings of highly porous spherical particles also shows a higher diffusivity compared to the same measurements. Further measurements will show whether a dependence on a particular shape property could explain this discrepancy.

[1] Macher, Wolfgang, et al. "Transmission probability of gas molecules through porous layers at Knudsen diffusion." Journal of Engineering Mathematics 144.1 (2024): 1-26.

[2] Güttler, Carsten, et al. "Simulation and experiment of gas diffusion in a granular bed." Monthly Notices of the Royal Astronomical Society 524.4 (2023): 6114-6123.

How to cite: Zivithal, S., Kargl, G., Macher, W., Güttler, C., Gundlach, B., Sierks, H., and Blum, J.: Studying gas flow on cometary surfaces with diffusivity variations using flow simulations and experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15837, https://doi.org/10.5194/egusphere-egu24-15837, 2024.

EGU24-17927 | ECS | Orals | PS3.1

Numerical inference of viscoelastic properties in tidal models of rubble pile asteroids 

Ethan Burnett, Iosto Fodde, and Fabio Ferrari

Tidal theory in binary asteroids is in a low state of development in comparison to that of planetary satellites. The dissipative processes within binary secondaries are divergent from the processes at work in planetary satellites, and also the evolutionary timescales are drastically shortened. To study the tidal torques and the spin evolution of the smaller secondaries in binary asteroid systems, it is believed to still be possible to apply a viscoelastic theory somewhat analogous to the models used for planetary satellites (see e.g. Murray & Dermott 1999). If this is true, then there should exist body-averaged “bulk” material properties, such as rigidity and viscosity, applicable for these models. Importantly, it should be possible to compute effective k2 (tidal potential Love number) and Q (quality factor) values for these tiny worlds.

Some pioneering works have derived first-order tidal laws for binary asteroids via analytic and semi-analytic methods. Nimmo & Matsuyama (Icarus 2019) derive a friction-driven effective quality factor Q which decreases (i.e. more dissipation) with stronger friction. Goldreich & Sari (The Astrophysical Journal 2009) argue that effective rigidity is dynamically dominant, deriving an important law for effective k2 for asteroids that scales linearly with the asteroid radius. They also argue that effective Q could be quite low for asteroids, lower than prior estimates of Q ~102. By contrast, Efroimsky (The Astronomical Journal 2015) argues that effective viscosity is dominant and rigidity doesn’t matter. Recently, Pou and Nimmo (Icarus 2024) showed that k2/Q values implied by the ages of some binary asteroids are much lower than the values predicted by Goldreich & Sari (2009), suggesting that the theory of the latter is incomplete.

In this work, we follow up on the aforementioned theoretical works with numerical experiments of binary asteroid tidal evolution, which have strong scientific motive to be carried out. This is accomplished using the massive N-body simulation architecture of GRAINS (Ferrari et al, MNRAS 2019), wherein gravitational, contact, and frictional effects are modeled in the interaction of thousands of non-spherical mass elements. We initialize a simplified binary system analogous somewhat to the scenarios employed in Agrusa et al (PSJ, 2022). To facilitate tidal locking, the static moment-of-inertia asymmetry is made sufficiently large, the secondary is initialized in a state of slightly super-synchronous rotation, and inter-element friction is enhanced, if needed, to yield a dissipation timescale in line with our numerical capabilities (a move inspired by the approach of Goldreich, The Astronomical Journal 1966). From our simulation results, we perform the following analysis:

  • A simple regression analysis infers the effective k2/Q from the computed rotational energy dissipation rate, via parallel application of the classical 1D MacDonald tidal dissipation model.
  • Previously derived scaling laws for effective k2 and Q are tested.
  • The accuracy of the MacDonald tidal torque model for binary rubble pile asteroids is tested.
  • With time permitting, if the (unimodal) MacDonald tidal model is shown to be inaccurate, we'll explore computation of an appropriate multimodal tidal potential, as in Darwin-Kaula theory.

How to cite: Burnett, E., Fodde, I., and Ferrari, F.: Numerical inference of viscoelastic properties in tidal models of rubble pile asteroids, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17927, https://doi.org/10.5194/egusphere-egu24-17927, 2024.

EGU24-18373 | ECS | Orals | PS3.1

Comet 12P/Pons-Brooks' Dust Fate 

Gabriel Borderes Motta, Daniel Kastinen, Johan Kero, and Maria Gritsevich

Gritsevich et al. (2022) studied the evolution of a dust trail from the massive outburst of comet 17P/Holmes in October 2007. They predicted that ground-based telescopes could observe this dust trail in 2022 and the subsequent observations were successfully conducted. The observations of the dust trail provide a valuable opportunity to study many peculiarities of the comet, including its activity, structure, and characteristics of the released dust particles. In the present work, we study dynamic evolution of the particles after a long period of time. We investigate the potential for a collision with Earth, Moon, and other celestial bodies; instants of high concentration of particles in the dust trail, and how the solar radiation pressure affects the dynamics of the dust. Recently, comet 12P/Pons-Brooks has experienced a series of well-documented outbursts during its current approach to perihelion, making it an exciting case for investigation. We simulate the evolution of dust particles released by the outbursts of comet 12P/Pons-Brooks during 2023. We use the software REBOUND for the simulations, integrating with the IAS15 numerical integrator. We initiate a system with the Sun, Venus, Earth, Moon, Mars, Jupiter, Saturn, Uranus, and the comet itself at the outburst date for the simulation. The results of the simulations are detailed and analyzed throughout the work.

 

References

Maria Gritsevich, Markku Nissinen, Arto Oksanen, Jari Suomela, Elizabeth A Silber, Evolution of the dust trail of comet 17P/Holmes, Monthly Notices of the Royal Astronomical Society, Volume 513, Issue 2, June 2022, Pages 2201–2214, https://doi.org/10.1093/mnras/stac822

How to cite: Borderes Motta, G., Kastinen, D., Kero, J., and Gritsevich, M.: Comet 12P/Pons-Brooks' Dust Fate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18373, https://doi.org/10.5194/egusphere-egu24-18373, 2024.

We have a long-term goal of creating a holistic and cross-disciplinary approach to meteor research where we connect together topics such as meteor measurements, ablation simulations, meteoroid stream simulations, and sensor simulations. Here, we present the most recent work on developing an automated radar data analysis algorithm able to calculate probability distributions of meteor- and meteoroid parameters for head echoes measured using interferometric high-power large-aperture radars. The algorithm utilizes direct Monte Carlo simulations of uncertainties, with Bayesian Markov-chain Monte Carlo estimation of meteor model parameters. The algorithm also employs N-body propagation of distributions to perform orbit determination, estimating the galactic background noise temperature for absolute-calibration and an statistical approach using many high signal-to-noise ratio meteors for phase calibration. This analysis algorithm has been applied to data from the Middle and Upper atmosphere (MU) radar in Shigaraki, Japan. As a first case study, we have re-analysed a part of the MU radar meteor head echo data set collected during 2009-2010. As a result we have confirmed the existence of a rare high-altitude radar meteor population with initial altitudes reaching up to ~150 km. Out of the total amount of 106 000 events, only 74 had an initial altitude >130 km, while four of those had an initial altitude >145 km.

How to cite: Kastinen, D. and Kero, J.: High-altitude radar meteors detected using a new analysis algorithm for interferometric meteor head echoes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18828, https://doi.org/10.5194/egusphere-egu24-18828, 2024.

EGU24-19273 | Orals | PS3.1

Near-Earth Objects’ Forecast of Collisional Events (NEOForCE). Impact monitoring system 

Dmitrii Vavilov and Daniel Hestroffer

Estimating the probability of a collision of asteroids with the Earth is an important task for planetary defense. There are systems that compute impact probabilities of near-Earth asteroids with the Earth on a regular basis: Sentry (Nasa, Jet Propulsion Laboratory) and CLOMON-2 (originally University of Pisa, now ESA). Here we present NEOForCE (Near-Earth Objects Forecast for Collisional Events) a new monitoring system developed at Institut de mécanique céleste et de calcul des éphémérides (IMCCE, Paris Observatory). This system is original and independent. As ephemeris of major planets and the Moon we use INPOP [1]. The asteroids’ orbits and covariance matrices are taken from DynAstVO database [2]. For computing the impact probability we use the Line Of Variation (LOV) sampling method [3] but with significant modifications. The longest axis of the confidence ellipsoid is chosen to be sampled obtaining virtual asteroids. Each virtual asteroid’s orbit is propagated from the time of discovery 100 years ahead with variational equations. Each virtual asteroid is a representative of its small vicinity and we apply the Partial Banana Mapping method (PBM) [5] for each of this vicinity to look for possible collisions. Then the results are combined and the procedure to find explicitly the initial conditions of the collisional trajectory is launched.

The main differences with the existing monitoring systems are: usage of INPOP ephemeris of major planets instead of DE, having our own orbit fitting and propagation procedure of asteroids from DynAstVO, and implementation of Partial Banana Mapping method. Hence the system provides an independent assessment of the impact probability, which in case of risks is crucial.

 

[1] Fienga, A., et al. (2020) INPOP new release: INPOP19a. Astrometry, Earth Rotation, and Reference Systems in the GAIA era. p. 293-297.

[2] Desmars J., et al. (2017) DynAstVO: a Europlanet database of NEA orbits. European Planetary Science Congress. 2017. p. EPSC2017-324.

[3] Milani A., et al. (2005) Nonlinear impact monitoring: line of variation searches for impactors. ICARUS, V. 173, p. 362-384.

[4] Vavilov D.E. (2020) The partial banana mapping: a robust linear method for impact probability estimation. MNRAS, V. 492, p. 4546–4552.

How to cite: Vavilov, D. and Hestroffer, D.: Near-Earth Objects’ Forecast of Collisional Events (NEOForCE). Impact monitoring system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19273, https://doi.org/10.5194/egusphere-egu24-19273, 2024.

EGU24-19491 | Orals | PS3.1

Superresolution color images from the sparse data cubes of the Hyperscout-H hyperspectral imager aboard the Hera mission 

Björn Grieger, Julia de León, Hannah Goldberg, Tomas Kohout, Gábor Kovács, Michael Küppers, Balázs Vince Nagy, and Marcel Popescu

On 26 September 2022, NASA's Double Asteroid Redirection Test (DART) mission impacted Dimorphos, the moonlet of near-earth asteroid (65803) Didymos, performing the world's first planetary defence test. ESA's Hera mission will be launched in October 2024 and rendezvous with the Didymos system end of 2026 or beginning of 2027. It will closely investigate the system and in particular the consequences of the DART impact.  

Hera carries the hyperspectral imager Hyperscout-H. Its sensor consists of 2048 x 1088 pixels which are arranged in macro pixel blocks of 5 x 5 pixels. The 25 pixels of each block are covered with filters in 25 different wavelengths where the center response ranges from 657 to 949 nm. Therefore, each of the 2048 x 1088 pixels provides only the brightness information for one wavelength and hence the theoretical 2048 x 1088 x 25 data cube is only sparsely populated. 

A simple straight forward approach to replenish the sparse data cube would be to move a 5 x 5 pixel window with one pixel steps horizotally and vertically over the whole frame and assign the obtained 25 wavelength spectrum to the center pixel of the window. Besides reducing the image resolution to the quite coarse macro pixels, the accuracy of this method is limited by pixel to pixel variations of the spectra and even more by varying albedo and shading effects caused by varying surface inclination. This makes the resultant spectra very noisy. 

In order to retrieve more accurate spectra with higher spatial resolution, we separate the spectrum at each micro pixel into a normalized spectrum and a brightness scaling factor. We assume the normalized spectra to be spatially smooth, but not necessarily the scaled spectra. Ratios of measured values are used to iteratively compute the normalized spectral value from adjacent pixels. After convergence, the spectra are brightness scaled to reproduce the measured values. This approach allows to replenish the complete data cube with full micro pixel resolution. The application to test images shows that spectra are recovered much more accurately than with the direct approach and that only very little spatial detail is lost. 

Having replenished the complete data cube allows us to construct color images at full micro pixel resolution. The three colors are sufficient to capture most of the spatial variation of the spectra of asteroid surfaces and hence the constructed color images provide a concise visualization of the respective full data cubes. 

How to cite: Grieger, B., de León, J., Goldberg, H., Kohout, T., Kovács, G., Küppers, M., Nagy, B. V., and Popescu, M.: Superresolution color images from the sparse data cubes of the Hyperscout-H hyperspectral imager aboard the Hera mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19491, https://doi.org/10.5194/egusphere-egu24-19491, 2024.

EGU24-19956 | Posters on site | PS3.1

Characterization of dust impact spots on various materials 

Jiří Pavlů, Libor Nouzák, Jan Wild, Libor Juha, Zoltan Sternovsky, Jana Šafránková, and Zdeněk Němeček

Understanding the interaction between dust grains and spacecraft materials is crucial for spacecraft dust observations. This study focuses on the characterization of hypervelocity space dust impact spots on a variety of materials commonly used in spacecraft construction. Utilizing laboratory-based experiments, we investigate the spots created by hypervelocity impacts.

Experimental setups involve subjecting different materials, including polymers, metals, and composites, to controlled impacts by accelerated micro-sized dust particles. We employ advanced imaging techniques, such as scanning electron microscopy (SEM), to analyze impact spots at micro and nanoscales. Energy-dispersive X-ray spectroscopy (EDS) is employed to assess compositional changes induced by impact events.

Preliminary results reveal unique impact signatures on diverse materials, showcasing variations in crater morphology, size distribution, and material response. The identification of surface modifications, including fractures, melting, and the formation of ejecta, provides valuable insights into the underlying physics of hypervelocity impacts on different materials. We attempt to extend our observations towards the ejecta creation efficency by various materials.

How to cite: Pavlů, J., Nouzák, L., Wild, J., Juha, L., Sternovsky, Z., Šafránková, J., and Němeček, Z.: Characterization of dust impact spots on various materials, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19956, https://doi.org/10.5194/egusphere-egu24-19956, 2024.

EGU24-20327 | Orals | PS3.1

Enstatite chondrite meteorites date the giant planet instability 

Chrysa Avdellidou, Marco Delbo, David Nesvorny, Kevin Walsh, and Alessandro Morbidelli

The identification of meteorite parent bodies provides the context for understanding planetesimal formation and evolution as well as the key solar system dynamical events they have witnessed. We identified that the family of asteroid fragments whose largest member is asteroid (161) Athor is the unique source of the rare EL enstatite chondrite meteorites (Avdellidou et al. 2022), the closest meteorites to Earth in terms of their isotopic ratios. The Athor family was created by the collisional fragmentation of a parent body 3 Gyr ago in the inner main belt (Delbo et al. 2019), however the diameter of the Athor family progenitor was much smaller than the putative size of the EL original planetesimal (Triellof et a. 2022). Therefore, we deduced that the EL planetesimal that accreted in the terrestrial planet region underwent a first catastrophic collision in that region, and one of its fragments suffered a more recent catastrophic collision in the main belt, generating the current source of the EL meteorites. 

We investigated the possible ways that could have brought the Athor family progenitor in its current position in the inner main belt. To do so, we used an interdisciplinary methodology where we combined laboratory meteorite thermochronometric data, thermal modelling, and dynamical simulations. 

We showed that planetesimal fragments from the terrestrial zone must have been implanted into the main asteroid belt at least 60 Myr after the beginning of the solar system. We concluded that the giant planet instability is the only dynamical process that can enable such implantation so late in the solar system timeline. 

Acknowledgements. We acknowledge support from the ANR ORIGINS (ANR- 18-CE31-0014). This work is based on data provided by the Minor Planet Physical Properties Catalogue (MP3C) of the Observatoire de la Côte d’Azur (mp3c.oca.eu).

References:

Avdellidou, Delbo, A. Morbidelli, Walsh, Munaibari, Bourdelle de Micas, Devogèle, Fornasier, Gounelle, & van Belle. Athor asteroid family as the source of the EL enstatite meteorites, 2022, A&A, 665, id.L9, 13 pp.

Delbo, Avdellidou, & Morbidelli, Ancient and primordial collisional families as the main sources of X-type asteroids of the inner main belt, 2019, A&A, 624, A69 

Trieloff, Hopp & Gail. Evolution of the parent body of enstatite (EL) chondrites, 2022, Icarus, 373, 114762

How to cite: Avdellidou, C., Delbo, M., Nesvorny, D., Walsh, K., and Morbidelli, A.: Enstatite chondrite meteorites date the giant planet instability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20327, https://doi.org/10.5194/egusphere-egu24-20327, 2024.

EGU24-22216 | Orals | PS3.1

Activities of the Comet Interceptor Comet Environment and Target Identification Working Groups 

Geraint Jones, Colin Snodgrass, Aurelie Guilbert-Lepoutre, Jean-Baptiste Vincent, Charlotte Goetz, Elena Martellato, Seiji Sugita, and Kueppers Kueppers

Comet Interceptor is an European Space Agency (ESA) mission in cooperation with the Japan Aerospace Exploration Agency (JAXA). It aims to characterise through a close flyby a long period comet, preferably dynamically new, or an interstellar object. The main spacecraft will be accompanied in its encounter with the target comet’s nucleus by two small probes, one provided by Europe, and the other by Japan. The mission is planned for launch in 2029. Its Science Working Team (SWT) is supported in specific scientific and science operation areas by Working Groups (WGs). These are the Target Identification WG and Comet Environment WG. The latter comprises three sub-WGs, covering the Nucleus, Near-Environment, and Far-Environment. Here, we provide a brief overview of the mission, and present and describe the aims and activities of the working groups. The search is already underway for potential comets to encounter, and preparations are being made for the scientific exploitation of the data from the mission’s three spacecraft.

How to cite: Jones, G., Snodgrass, C., Guilbert-Lepoutre, A., Vincent, J.-B., Goetz, C., Martellato, E., Sugita, S., and Kueppers, K.: Activities of the Comet Interceptor Comet Environment and Target Identification Working Groups, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22216, https://doi.org/10.5194/egusphere-egu24-22216, 2024.

EGU24-1981 | Posters on site | PS4.1

Solar wind controls on Martian proton aurora brightening and atmospheric ion loss intensifying 

Fei He, Kai Fan, Andrea Hughes, Yong Wei, Jun Cui, Nicholas Schneider, Markus Fraenz, Xiao-Xin Zhang, Qingyu Meng, and Xiaodong Wang

Charge exchange between solar wind protons and local hydrogen atoms generates hydrogen energetic neutral atoms (H-ENAs) in the extended neutral hydrogen corona surrounding Mars. The following collisions between H-ENAs and atmospheric molecules generate a distinct proton aurora. How the solar wind influences the proton aurora activity in the short term is not well unknown. We found that there are synchronized proton aurora brightening and atmospheric ion loss intensifying on Mars, both controlled by solar wind dynamic pressure, using observations by the Mars Atmosphere and Volatile Evolution spacecraft. Significant erosion of the Martian ionosphere during periods of high dynamic pressure indicates at least five-to-tenfold increase in atmospheric ion loss. An empirical relationship between ion escape rate and auroral emission enhancement is established, providing a new proxy of Mars’ atmospheric ion loss with optical imaging that may be used remotely and with greater flexibility.

How to cite: He, F., Fan, K., Hughes, A., Wei, Y., Cui, J., Schneider, N., Fraenz, M., Zhang, X.-X., Meng, Q., and Wang, X.: Solar wind controls on Martian proton aurora brightening and atmospheric ion loss intensifying, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1981, https://doi.org/10.5194/egusphere-egu24-1981, 2024.

EGU24-2004 | Posters on site | PS4.1

Ion escape processes in the solar system and beyond  

Iannis Dandouras and Masatoshi Yamauchi

Understanding the evolution of planetary atmospheres, and particularly the evolution of their composition and eventual habitability, is a major challenge. The evolution of an atmosphere is driven by its interactions with the planetary surface and interior, the influx from space (e.g. meteors), and the atmospheric escape to space in the form of neutral or ionised atoms/molecules, upwelling from the atmosphere and escaping to space.
For a planet like Earth, atmospheric escape in the form of neutrals concerns essentially hydrogen whereas heavier species, such as oxygen and nitrogen which constitute 99% of the mass of the terrestrial atmosphere, need to be accelerated as ions in order to reach escape velocities. The ions that outflow from the ionosphere are successively accelerated through a series of energisation mechanisms and can eventually reach velocities above the gravitational escape velocity.
Missions like Cluster, MAVEN and Cassini and associated modelling efforts have advanced our understanding of the ion acceleration, circulation in the magnetosphere and escape mechanisms operating on different planetary objects of our solar system, magnetised or unmagnetised.
However, several questions remain open, as:
(i) What is the exact composition of the escaping populations and how does it change in response to the different driving conditions?  How does it affect the long-term evolution of the composition of a planetary atmosphere and its habitability?
(ii) What is the exact degree of plasma recirculation for each ion species, after it has left the ionosphere, versus direct or indirect escape, and what is its dependence on the solar and geomagnetic activity conditions?
(iii) What is the effect of a planetary magnetic field on the different escape mechanisms, particularly in view of the conjugate effect of different magnetospheric size / solar wind dynamic pressure / exobase altitude / solar irradiance?
(iv) The discovery in recent years of a large number of exoplanets, several of them in the "habitable" zone, raises the question of atmospheric escape mechanisms operating in these environments. Could exoplanets orbiting active K-M stars undergo massive atmospheric escape, removing the constituents of water from their atmospheres under XUV irradiation and making them uninhabitable within a few tens to hundreds of Myr, as some models suggest? 

 

 

How to cite: Dandouras, I. and Yamauchi, M.: Ion escape processes in the solar system and beyond , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2004, https://doi.org/10.5194/egusphere-egu24-2004, 2024.

EGU24-2078 | ECS | Posters on site | PS4.1

Theory and fluid simulations of ion and electron acoustic instabilities in Parker Solar Probe observations close to the Sun. 

Mahmoud Saad Afify, Jürgen Dreher, and Maria Elena Innocenti

Multiple electron and ion beams have been observed by the Parker Solar Probe (PSP) in the low solar atmosphere (Sun et al. 2021; Liu et al. 2023). In the presence of two resonant counter-steaming ion and electron populations, we expect the development of ion and electron acoustic instabilities, respectively (Mozer et al. 2020; Chen et al. 2020; Verscharen et al. 2022). Ion acoustic waves have indeed been observed by PSP (Mozer et al. 2021 a,b, 2023a) with characteristics that differ from previous observations. The latter is a coupled pair of high and low frequencies. Moreover, they have an electrostatic nature and a long duration of several hours. Their importance comes from the absence of whistler waves very close to the Sun, which seem to play a major role in heat flux regulation further away from the Sun (Halekas et al. 2021; Micera et al. 2021) and the recent observations that ensure the heating of core electrons and ions during the existence of such electrostatic waves (Kellogg 2020; Cattell et al. 2022; Mozer et al. 2022, 2023b). Employing the theory and multi-fluid simulations for both ion and electron acoustic instabilities (Kakad et al. 2013; Kakad & Kakad 2019; Afify et al. 2023) in plasma regimes compatible with PSP observations gives reasonable results. However, this study will be complemented by kinetic simulations with a fully kinetic code that implements solar wind plasma expansion self-consistently, EB-iPic3D (Innocenti et al. 2019), since the fluid analysis is unable to address the contribution of resonant electrons when the wave phase velocity is close to the electron thermal velocity. Indeed, the fluid simulations can capture decently the linear stage of these instabilities while becoming less accurate in the nonlinear stage (Kakad et al. 2014). This study highlights many phenomena, such as the mechanism behind the onset and propagation of different time domain structures such as electron and ion acoustic waves, how they modify the electron-ion velocity distribution functions, and the heating of the core electrons and ions.

How to cite: Afify, M. S., Dreher, J., and Innocenti, M. E.: Theory and fluid simulations of ion and electron acoustic instabilities in Parker Solar Probe observations close to the Sun., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2078, https://doi.org/10.5194/egusphere-egu24-2078, 2024.

EGU24-4846 | ECS | Posters on site | PS4.1

Variation Martian proton aurora in different timescales 

Jingyi Wu, Fei He, Yong Wei, and Andrea Hughes

The aurorae on Mars are divided into diffuse aurora, discrete aurora and proton aurora. Proton aurora is the most common type of aurora on Mars. The proton aurora on Mars is formed when protons in the solar wind pass through the Martian hydrogen corona and undergo charge exchange to form energetic neutral atoms, which deposit energy in the Martian atmosphere. Previous research results showed that the main external factors that affect the occurrence rate, emission enhancement, intensity and peak height of proton aurora are the solar wind particle flux and velocity, solar zenith angle and solar longitude. Here, we extend the previous proton aurora database compiled by Hughes et al. [2019], which was in the descending phase of the last solar cycle between 2014-2018, to present with similar algorithm. Using this new database covering almost one solar cycle, we investigated the long-term variations of the proton aurora on Mars in three timescales, including the solar rotation cycle, Martian season, and solar cycle. The results will help us understand the solar wind-Mars interactions.

How to cite: Wu, J., He, F., Wei, Y., and Hughes, A.: Variation Martian proton aurora in different timescales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4846, https://doi.org/10.5194/egusphere-egu24-4846, 2024.

EGU24-5648 | Posters on site | PS4.1

Very minor ions in the magnetosphere: a hub of the mesospheric, ionospheric, magnetospheric, solar wind, lunar, and meteoroid sciences. 

Masatoshi Yamauchi, Iannis Dandouras, Peter Würz, Daniel Kastinen, John Plane, Leonard Schulz, Andrew Yau, Lynn Kistler, Steve Christon, Stein Haaland, Yoshifumi Saito, Satonori Nozawa, Ingrid Mann, Shigeto Watanabe, and Tinna Gunnarsdottir

This is the summary of findings by ISSI topical team on the molecular and metallic ions in the magnetosphere.

Heavy molecular and metallic ions with mass ≥ 27 (Al+, N2+, NO+, O2++, Fe+, Cu+, Ti+, etc) in the magnetosphere provide independent information on the ion sources and entry route to the magnetosphere from traditional four components (H+, He++, He+, O+). There are four ultimate sources of these heavy molecular and metallic ions: the solar wind (high charge-state metallic ions), the ionosphere (mainly molecular ions), the atmospheric metal layers (low charge-state metallic ions and metal-rich molecular ions that ultimately originating from ablation of meteoroids and possibly space debris), and the surface and exosphere go the Moon (low charge-state metallic and molecular ions). 

The lunar origin low charge-state metallic ions, if separated from the ionospheric origin, give independent information on the entry route into the magnetosphere for ions of much larger gyroradius than the solar wind ions. The atmospheric-origin molecular ions are essential in understanding energization, ionization altitudes, and upward transport in the ionosphere during various ionospheric and magnetospheric conditions. These ions are also important when considering the evolution of the Earth's atmosphere on the geological timescale. 

So far, we cannot dismiss any of four possible sources with the existing data because only a few terrestrial missions have been equipped with instrumentation dedicated to separate these molecular and metallic ions, within only a limited energy range (cold ions of < 50 eV and energetic ions of ~100 keV or more) and a limited mass range (mainly ≤ 40 amu). This is far too limited to make any quantitative discussion on the very heavy ions in the magnetosphere.  Under this circumstance, it is worth to re-examine, using available tools, the existing data from the past and on-going missions, including those not designed for the required mass separation, to search for these ions.  

We synthesised these patchy observations and combining all sources with updated models. With such knowledge, we re-examined available data and model that actually provided important indications of the sources of these heavy ions and their amounts that have been overlooked to date.  Finally, we note the possible future contamination of specific masses by ablated space debris (Al, but also Li, Fe, Ni, Cu, Ti, and Ge) in the coming decades.

How to cite: Yamauchi, M., Dandouras, I., Würz, P., Kastinen, D., Plane, J., Schulz, L., Yau, A., Kistler, L., Christon, S., Haaland, S., Saito, Y., Nozawa, S., Mann, I., Watanabe, S., and Gunnarsdottir, T.: Very minor ions in the magnetosphere: a hub of the mesospheric, ionospheric, magnetospheric, solar wind, lunar, and meteoroid sciences., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5648, https://doi.org/10.5194/egusphere-egu24-5648, 2024.

EGU24-5907 | Orals | PS4.1

Study of magnetosphere dynamics combing geospace and planetary missions 

Rumi Nakamura, James Slavin, Daniel Schmid, and Weijie Sun and the Bepicolombo Earth-Flyby Interval Substorm Study Team

Solar system missions studying the sun and the planets in the inner and outer heliosphere use gravity assists of the planets to reach the target orbit of the missions. If such a maneuver happens around Earth, these observations enable us a unique multipoint observation of the magnetosphere together with other existing geospace missions as was the case of the Bepicolombo in April 2020 and the Solar Orbiter in November 2021 and is expected for JUICE in August 2024. Although the spacecraft during flybys are usually not operated in a full science mode, a new constellation with other fleet of spacecraft in Geospace can provide important information in particular for studying large-scale magnetospheric dynamics.

In this presentation we discuss the three-dimensional evolution of the magnetotail current of a substorm on April 10, 2020 that took place during the Earth-flyby interval of Bepicolombo. Magnetotail disturbances are observed by GOES 17 and Cluster in the midnight region, while BepiColombo spacecraft traversed the premidnight region duskward at 9-11 RE downtail. The four Cluster satellites, which were separated mainly in north-south direction, crossed the inner magnetosphere successively from north to south. They enable us to monitor the vertical (latitudinal) structure and the sequential changes of the magnetotail current sheet until the end of the recovery phase of the substorm. Multiple dipolarizations and multiple transient field-aligned currents (FAC) were observed by Cluster. Using the unique dataset from these multi-point observations, we examine the structure of the large-scale current sheet and analyze the embedded transient intense field-aligned current disturbances. By also comparing the observations with an empirical magnetic field model, we obtain the changes of the near-Earth magnetotail structure during the multiple dipolarization event.

How to cite: Nakamura, R., Slavin, J., Schmid, D., and Sun, W. and the Bepicolombo Earth-Flyby Interval Substorm Study Team: Study of magnetosphere dynamics combing geospace and planetary missions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5907, https://doi.org/10.5194/egusphere-egu24-5907, 2024.

Space weather, i.e. the conditions in space driven by the dynamic solar activity, is a terminology that has been traditionally used to refer to the Sun’s effects on the near-Earth environment. This is because of a rather obvious reason, namely that most of the technological systems susceptible to space weather conditions and all human beings are currently on Earth or in near-Earth space. Hence, space weather research and forecasting efforts have focussed for decades mainly on our own neighbourhood. Nevertheless, in more recent years there has been a paradigm shift, due to which the field of space weather science has been gradually evolving into a heliosphere-wide discipline. This has been motivated by two main factors: (1) a growing interest in human exploration outside the Earth–Luna system, with efforts centred especially on Mars, and (2) an increasing endeavour from the research community to view the solar system as a Sun–heliosphere–planets integrated environment.

In this presentation, we will first provide a brief overview of the more “traditional” approach of space weather science to studying the Sun and its transient phenomena—e.g., the structured solar wind, coronal mass ejections, and solar energetic particles. We will then showcase more recent efforts that have been centred on taking advantage of data from missions scattered throughout the solar system to analyse space weather events at multiple points in the heliosphere and their effects on different planetary environments. Finally, we will highlight current and future opportunities for advancing our knowledge of the Sun and space weather-driving phenomena across the heliosphere. Particular emphasis will be given to possible synergies between different subjects of solar system science—i.e. solar, heliospheric, and planetary—and to ideas for the future in terms of multi-disciplinary space missions that can improve our understanding of space weather phenomena from a fundamental physics standpoint and, at the same time, that can expand our knowledge of space weather drivers and effects at other locations than Earth.

How to cite: Palmerio, E.: Space weather today: From an Earth-centred discipline to a heliosphere-wide field of research, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7037, https://doi.org/10.5194/egusphere-egu24-7037, 2024.

Open magnetic flux (OMF) emanating from the Sun permeates the entire interplanetary space and plays an important role in all physical processes throughout the heliosphere that involve magnetic fields. It has been a topic of investigation based on both observational and numerical model analysis. And yet, there are still unresolved debates surrounding the OMF, considered to be among the big open questions in the field of solar and space physics. One of these is the “missing” open flux problem, according to which photospheric open flux estimates do not match measurements made in situ at 1 au. These photospheric estimates are obtained based on two different methods. According to the first, extreme ultraviolet (EUV) observations of coronal holes (CHs), that are considered as primary sources of OMF, are overlaid over global magnetic maps (Carrington maps), and the magnetic flux they enclosed is summed up. The second method is based on areas of open flux determined by coronal models and the summation of the magnetic flux they enclose. However, regardless of the complexity of coronal models, current research has shown that modelled open flux strongly underestimates that determined by the first method, and both underestimate the flux measure in situ at 1 au, by at least a factor of 2. These comparisons with values measured at 1 au are based on the conclusion made by Ulysses’ observations of the latitudinal invariance of the magnitude of the radial interplanetary magnetic field, which lead to the consensus that the total heliospheric open flux can be calculated by a single point in situ measurements. The aforementioned discrepancies have raised many questions. Are observational limitations responsible for the missing open flux? Are model limitations, such as the complexity of the model, the numerical implementation, and uncertainties in input data, contributing to the problem? How can we constrain and validate coronal models? Do we fully understand the sources of open flux? During this presentation we will navigate through research contributing to answering these questions and the direction of current and future efforts both in modelling and observations.

How to cite: Asvestari, E.: Exploring the heliospheric open flux problem from multiple perspectives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7959, https://doi.org/10.5194/egusphere-egu24-7959, 2024.

EGU24-9364 | ECS | Posters virtual | PS4.1

Serverless Computing Architecture for Enhanced Martian Aurora Detection in the Emirates Mars Mission 

David Pacios, José Luis Vázquez-Poletti, Dattaraj B. Dhurri, Dimitra Atri, Rafael Moreno Vozmediano, Robert J. Lillis, Nikolaos Schetakis, Jorge Gómez-Sanz, Alessio Di Iorio, and Luis Vazquez

This work introduces a novel serverless computing architecture designed to analyze Martian auroras for the Emirates Mars Mission (Hope probe). Utilizing OpenCV and machine learning algorithms, the architecture offers efficient and scalable image classification, object detection, and segmentation. It leverages cloud computing's scalability and elasticity, handling large volumes of image data and adapting to varying workloads. Our study highlights the system's capacity to process and analyze images of Martian auroras swiftly while maintaining cost-effectiveness. The application of this technology within the HOPE Mission not only addresses the complexities involved in detecting Martian auroras but also sets a precedent for future remote sensing applications. Our results demonstrate the potential of serverless computing in enhancing the analysis of extraterrestrial phenomena and contributing significantly to planetary science.

This contribution has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No.101007638 (Project EYE - Economy bY spacE) .

How to cite: Pacios, D., Vázquez-Poletti, J. L., Dhurri, D. B., Atri, D., Moreno Vozmediano, R., Lillis, R. J., Schetakis, N., Gómez-Sanz, J., Di Iorio, A., and Vazquez, L.: Serverless Computing Architecture for Enhanced Martian Aurora Detection in the Emirates Mars Mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9364, https://doi.org/10.5194/egusphere-egu24-9364, 2024.

Aurora has been detected on a few occasions on the Venus nightside with the Pioneer Venus UltraViolet Spectrometer (PVO-UVS). The main characteristics are the presence of the OI 130 and 136 nm emissions, a lack of discrete structure (diffuse aurora) and correlation with interplanetary shocks. Ground-based observations in the visible have shown that the [OI] green line at 557.7 nm is also observed following periods of the solar wind intensification. Although no concurrent measurement of auroral particle precipitation has been made, numerical simulations of the UV emissions have indicated that precipitation of soft auroral electrons (15-20 eV) and low energy fluxes is a likely candidate.

A discrete aurora was first observed in the middle ultraviolet on the Martian nightside limb from the Mars Express orbiter in a region of strong crustal field in the southern hemisphere. Prominent emissions included the CO Cameron bands and the CO2+ UV doublet.  Limb observations have been made from Mars Express and MAVEN during the last 10 years. Recently, global auroral images have been collected with the UltraViolet Spectrometer (EMUS) on board the Emirates Mars Mission (EMM). These observations reveal a wide variety of auroral morphologies including discrete, diffuse, proton and sinuous aurora, each one bearing the signature of the interaction between the solar wind, the induced (or crustal) magnetic field and the atmosphere.

In this presentation, we compare the characteristics of the Venus and Mars diffuse aurora observed by Pioneer Venus and MAVEN respectively. We focus on the determination of the charged particles characteristics (mean energy, flux, energy distribution) based on the brightness and intensity ratio of spectral emissions. Following recent laboratory measurement of the efficiency of the Cameron bands excitation by electron impact, we re-examine the dependence of the Cameron/CO2+ UVD intensity ratio on the auroral electron energy. Similarly, the different shapes of the electron excitation cross sections of the OI emissions at 130 and 136 nm induces an intensity ratio that depends on the energy of the precipitation. This dependence can be used to map the mean electron energy, based on FUV spectral observations with the EMUS. Finally, we discuss the expected brightness of the Mars visible aurora and set an upper limit on the intensity of the OI green line based on attempts to detect it with the UVIS spectrometer on board the Trace Gas Orbiter. We show that global observations with the M-AC visible camera on board the M-MATISSE orbiters will generate considerable progress in our understanding of the morphology, time variations and energetics of the Martian aurora.

 

How to cite: Gérard, J.-C. and Soret, L.: Spectroscopy of Mars and Venus aurora: a remote sensing tool for similarities and differences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9791, https://doi.org/10.5194/egusphere-egu24-9791, 2024.

EGU24-10912 | Orals | PS4.1

Magnetosheath jets: an interdisciplinary perspective 

Ferdinand Plaschke

Earth’s magnetosheath, particularly its region downstream of the quasi-parallel bow shock, is permeated by plasma jets. These are local enhancements in the dynamic pressure, bubbles of plasma that are typically faster and denser in comparison to the ambient plasma. While jets emanate from the patchy and rippled quasi-parallel bow shock or upstream foreshock region, they are able to cross the entire magnetosheath and impact on the magnetopause. There, they may trigger magnetic reconnection and magnetopause surface waves, thereby coupling into large-scale magnetospheric dynamics. Consequently, the effects of jets can be observed inside the magnetosphere and also from ground. Jets are conceptually highly interesting phenomena as they can be interpreted as coupling elements between different regions and vastly different scales. Interdisciplinary research has led to significant advances in our understanding of jets over the past decade. However, despite all the efforts, many basic and fundamental questions remain unanswered. We review some latest results and open questions in jet research, emphasizing the benefit of interdisciplinary approaches.

How to cite: Plaschke, F.: Magnetosheath jets: an interdisciplinary perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10912, https://doi.org/10.5194/egusphere-egu24-10912, 2024.

EGU24-13286 | Posters on site | PS4.1

Unveiling the Mysteries of Multiscale Magnetotail Dynamics with the CINEMA Constellation 

Sasha Ukhorskiy and Robyn Millan and the CINEMA Science Team

Planetary magnetospheres are among the most dynamic and complex systems studied in heliophysics. Driven by their stellar environment and internal sources (e.g., planetary rotation or moons), these vast reservoirs of magnetic energy exhibit a range of dynamical states. Energy circulation (convection) through the system can be steady or explosive, triggering fast plasma flows, global current systems, and spectacular auroral displays. Understanding the response of magnetospheres to their stellar environment is essential for understanding the nature of our home in space, a key heliophysics goal. In Earth’s solar wind–driven magnetosphere, the magnetotail is a key region through which energy is circulated. How the magnetotail maintains steady convection, and when and how it decides to explosively release stored energy, are major unsolved mysteries of space physics. A significant challenge is the intrinsically multiscale nature of magnetotail convection, which is difficult to capture with the sparse measurements available so far. The CINEMA (Cross-Scale INvestigation of Earth’s Magnetotail and Aurora) SMEX Phase A Mission Concept will provide a new cross-scale view of the magnetotail, revealing its large-scale configuration and its influence on dynamics at smaller scales. With a constellation of 9 spacecraft in low-earth orbit all equipped with a full complement of high-resolution energetic particle sensor, auroral imagers, and magnetometers, CINEMA will capture the plasmasheet structure and evolution key for unveiling the mysteries of multiscale magnetospheric convection.  

How to cite: Ukhorskiy, S. and Millan, R. and the CINEMA Science Team: Unveiling the Mysteries of Multiscale Magnetotail Dynamics with the CINEMA Constellation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13286, https://doi.org/10.5194/egusphere-egu24-13286, 2024.

EGU24-13384 | Orals | PS4.1

Mars Aurora: A Comparison of MAVEN/IUVS and EMM/EMUS Observations 

Nicholas Schneider, Robert Lillis, Sonal Jain, Justin Deighan, Julianna Cessna, Michael Chaffin, Andrea Hughes, Krishnaprasad Chirakkil, Jean-Claude Gérard, and Lauriane Soret

Mars' lack of a global magnetic field led to initial expectations of minimal auroral activity. Mars Express's SPICAM instrument nonetheless discovered an unusual form of aurora in 2005. The ultraviolet emissions were confined near Mars' strong crustal field region, showing that even weak magnetic fields can be responsible for aurora. These discrete aurora emissions were identified in 19 observations over SPICAM's decade of observations. 

The MAVEN spacecraft arrived at Mars in 2014 carrying the Imaging UltraViolet Spectrograph (IUVS). Thanks to its high sensitivity and observing cadence, IUVS increased detections of discrete aurora twenty-fold. IUVS also discovered two new widespread forms of aurora. Diffuse aurora is a planet-engulfing phenomenon, caused by solar energetic protons and electrons directly impacting the entire unshielded planet. Proton aurora is caused by solar wind protons charge-exchanging into the atmosphere and causing Lyman alpha emission across the dayside. IUVS studies the aurora at mid- and far-UV wavelengths in both limb scans and nadir imaging.

The Emirates Mars Mission (EMM) arrived in 2021 carrying the Emirates Mission UltraViolet Spectrometer (EMUS). EMUS quickly added to the menagerie of auroral phenomena thanks to its high far-UV sensitivity. Discrete aurora emissions were seen in a substantial fraction of nightside observations, and appear to take on new forms not seen by IUVS (sinuous"non-crustal field", among others). Furthermore, EMUS detected a spatially-variable form of proton aurora called patchy proton aurora. EMUS studies the aurora through nadir imaging at far- and extreme-UV wavelengths.

The net result of the tremendous influx of new observations is a lag in cataloguing and cross-comparing the types of observations made with different instruments at different wavelength ranges in different observing modes. We now have the perspective to identify the causes of these auroral phenomena, which gives a more physics-based nomenclature:

  • suprathermal electron aurora: hot electrons from the Mars environment appear to be responsible for most forms of discrete aurora
  • solar energetic particle aurora: SEP electrons and protons from the Sun cause the planet-wide diffuse aurora 
  • solar wind aurora: solar wind protons charged-exchange into the atmosphere to cause dayside aurora

This presentation seeks to give that broader context, highlighting

  • what phenomena IUVS and EMUS observe, depending on their distinct instrumental capabilities
  • whether they’re actually seeing the same phenomena or different ones, 
  • how can one type of observation can complement the other, 
  • where one’s capabilities are unique, and 
  • what are the best directions for collaboration;
  • how in situ measurements of particles and fields can contribute to the next stage of understanding of the conditions for particle precipitation

A more coherent observational perspective, as outlined above, may grant a framework for developing a deeper physical understanding of Mars unexpected diverse auroral processes.

How to cite: Schneider, N., Lillis, R., Jain, S., Deighan, J., Cessna, J., Chaffin, M., Hughes, A., Chirakkil, K., Gérard, J.-C., and Soret, L.: Mars Aurora: A Comparison of MAVEN/IUVS and EMM/EMUS Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13384, https://doi.org/10.5194/egusphere-egu24-13384, 2024.

EGU24-13610 | Orals | PS4.1 | Highlight

Exploring Mars discrete aurora with synoptic images and movies from EMM EMUS 

Robert Lillis, Krishnaprasad Chirakkil, Justin Deighan, Matthew Fillingim, Sonal Jain, Michael Chaffin, Susarla Raghuram, Gregory Holsclaw, Hoor Almazmi, David Brain, Nick Schneider, Shaosui Xu, Jasper Halekas, Jared Espley, Jacob Gruesbeck, and Shannon Curry

Benefiting from a large orbit and high sensitivity, the Emirates Mars mission EMUS instrument has provided the first opportunity to synoptically and regularly image Mars’ discrete FUV auroral oxygen emission at 130.4 and 135.6 nm.  Over 15-20 minutes, EMUS produces a) images by slewing its aperture slit across the disk or b) “movies” of narrow regions by staring continuously.

Discrete aurora are observed primarily where the magnetic topology is open (i.e. connected to the collisional atmosphere at one end), which occurs where Mars’ crustal magnetic fields are either very weak or primarily vertical.  Discrete aurora show a strong local time dependence, with occurrence % decreasing with increasing solar zenith angle.  The highest occurrences are generally found in the post-dusk sector, before 10 PM SLT, though a few regions (e.g. 60°-70° S, 120°-150° E) are brightest between midnight and 3 AM.   

Sinuous discrete auroras (SDA) are enigmatic, sharply-defined filamentary emissions identified in approximately 3% of observations. These emissions intersect Mars' UV terminator, aligning generally away from the Sun, tending to cluster into groups oriented to the north, south, east, and west. The occurrence of SDAs increases with higher solar wind pressure. SDAs have a tendency to form toward the direction of the solar wind convection electric field (i.e., forming in the +E hemisphere). Depending on whether they originate near dusk or dawn, there is a moderate clockwise or counterclockwise "twist" observed in the average orientation of SDAs, respectively. Based on these characteristics, we infer a connection between SDAs and Mars' magnetotail current sheet, suggesting that the emission may be a result of energized electrons within this sheet.

Lastly, near the dawn and dusk terminators, discrete aurora often display a preference for formation in regions of either positive or negative crustal magnetic field, depending on IMF direction.  This preference can be used to determine whether a dayside (magnetosheath or photoelectron) or nightside (magnetotail) source of electrons is dominant.  Overall, nightside sources dominate over dayside by 20-40%, although individual radial crustal fields can show strong preferences for day or night sources.  This tells us that local magnetic geometry plays a role in global precipitation patterns.

With more than 3000 nightside images and 400 aurora movies collected (totaling more than 12 million pixels) since April 2021, we now have a powerful tool to understand Martian aurora morphologies, variability, and dependence on internal and external drivers. 

How to cite: Lillis, R., Chirakkil, K., Deighan, J., Fillingim, M., Jain, S., Chaffin, M., Raghuram, S., Holsclaw, G., Almazmi, H., Brain, D., Schneider, N., Xu, S., Halekas, J., Espley, J., Gruesbeck, J., and Curry, S.: Exploring Mars discrete aurora with synoptic images and movies from EMM EMUS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13610, https://doi.org/10.5194/egusphere-egu24-13610, 2024.

EGU24-14121 | ECS | Orals | PS4.1

Application of machine learning for modeling and characterizing electron and proton auroras on Mars 

Dattaraj Dhuri, Dimitra Atri, and Sonya Hseih

Auroras on Mars are known since their first discovery in 2005 by Mars Express and subsequently have been observed by Mars Atmosphere and Volatile Evolution (MAVEN) since 2014. Since 2021, Emirates UV spectrometer (EMUS) onboard the Emirates Mars Mission (EMM) has been observing Martian auroras with an unprecedented frequency. These auroras are seen as FUV and EUV emissions of H, O, CO, and CO2 and are categorized based on their morphologies and the particles that are responsible for these emissions. Electron precipitation on the nightside causes discrete and diffuse auroras whereas solar wind protons penetrating the Mars atmosphere cause proton auroras on the dayside. EMUS also detected new discrete auroras extending thousands of km into the nightside with a sinuous morphology. The variety and abundance of Mars aurora occurrences make them an important tool for gaining new insights into solar wind interaction with Mars's magnetosphere. Mars aurora research therefore involves characterizing aurora occurences in terms of solar activity, seasonal variability, IMF orientation, crustal magnetic fields, and energies of precipitating particles. In this work, we present applications of machine learning for modeling proton auroras as well as automatically detecting discrete electron auroras, leveraging a plethora of MAVEN and EMUS observations. We also focus on explainability of these ML models, commonly perceived as “black-boxes”, and approaches to analyze and validate correlations learned by these models. We discuss in detail the characteristics of proton and electron auroras thus revealed by these models and present future directions for such applications on Mars and other planets.

How to cite: Dhuri, D., Atri, D., and Hseih, S.: Application of machine learning for modeling and characterizing electron and proton auroras on Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14121, https://doi.org/10.5194/egusphere-egu24-14121, 2024.

EGU24-14406 | ECS | Posters on site | PS4.1

The Solar Wind: A net source or sink for terrestrial mass? 

Parker Hinton, David Brain, Neesha Schnepf, Riku Jarvinen, and Fran Bagenal

Shortly after the solar wind was first measured by the Second Soviet Cosmic Rocket (Luna 2) in 1959, planetary scientists immediately began wondering if it might be a source of mass for terrestrial atmospheres; perhaps even providing the Earth with all of the hydrogen needed for its oceans (De Turville 1961). This particular idea has been shown not to hold water, moreover, it is now known that the solar wind can drive escape from planetary atmospheres in the form of pick up ions. This presentation highlights an unresolved question: does the solar wind represent a net source or sink of mass for the terrestrial planets? We approach the problem using an ion-kinetic quasi-neutral hybrid (QNH) particle-in-cell (PIC) code called Rhybrid. We simulate the interaction of the solar wind with non-magnetized and weakly-magnetized terrestrial-type planets ranging in size from Mars to super Earth (1.5 RE). We also vary the ion production rate and dipole moment strength in order to explore the relevant parameter space. We quantify the escape rate of planetary ions (H+ and O+), as well as the accretion rate of solar hydrogen, and present the net mass flux for the different modeled scenarios.

How to cite: Hinton, P., Brain, D., Schnepf, N., Jarvinen, R., and Bagenal, F.: The Solar Wind: A net source or sink for terrestrial mass?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14406, https://doi.org/10.5194/egusphere-egu24-14406, 2024.

Auroral emissions have been observed throughout the Solar System. They are the photo-manifestation of the interaction of energetic, extra-atmospheric particles (typically electrons or ions) with an atmosphere. As the source of energy comes from the space environment (e.g., solar wind or magnetosphere if applicable), the auroral emissions are a tracer of plasma bombardments in an atmosphere. They are also a fingerprint of plasma source and atmospheric species. They are an invaluable, remote-sensing probe of plasma interaction in the Solar System.

Through a multi-instrument analysis of gas, particle and spectroscopic dataset from Rosetta, we have established that the atomic emissions observed in the coma of comet 67P at large heliocentric distances (> 2 astronomical units) are of auroral origin [Galand et al., Nature Astronomy, https://doi.org/10.1038/s41550-020-1171-7, 2020; Stephenson et al.., A&A, https://doi.org/10.1051/0004-6361/202039155, 2021]. We will discuss the source of the energetic particles responsible for the Far UltraViolet (FUV) emissions and will highlight the relevance of observing some of them from Earth. We will contrast these emissions with those observed at comets in the soft X-rays and extreme ultraviolet and with the FUV emissions observed at Earth, Mars and Ganymede.

How to cite: Galand, M.: Far Ultraviolet atomic emissions at comet 67P: What have we learned? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16001, https://doi.org/10.5194/egusphere-egu24-16001, 2024.

EGU24-19005 | ECS | Orals | PS4.1

The Balance of Internal and External Drivers in Gas Giant Magnetospheres 

Matthew J. Rutala, Caitriona M. Jackman, Alexandra R. Fogg, Sophie A. Murray, Mathew J. Owens, and Chihiro Tao
The magnetospheres of the gas giants are characterized by strong planetary magnetic fields, rapid rotation, and an intriguing, but not fully characterized, mix of external (solar wind) and internal driving of magnetospheric processes, including the aurorae. Determining the balance between these internal and external drivers is made difficult by the limitations of single-spacecraft measurements, which represent the vast majority of all in-situ magnetospheric measurements and upstream solar wind measurements at the giant planets. Simultaneous in-situ measurements, upstream solar wind monitoring, and remote sensing (e.g. multi-wavelength auroral imaging), gives the best chance to characterize internal and external drivers. Such data have only been taken once, during the brief coordination of the Galileo and Cassini spacecraft at Jupiter. In lieu of a large dataset of simultaneous measurements, advances in our statistical understanding of the balance between these internal and external drivers have been made by leveraging models of either the solar wind, giant planet magnetospheres, or both.

In the coming years, additional in-situ data, upstream monitoring, and remote observations coordinated either between space- or earth-based observatories will provide more context for understanding the giant planet magnetospheres, including potential coordination between JUICE and Europa Clipper. In the meantime, improved statistical analysis of both models and data are our best tools to better understand these systems. To this end, we will present the Multi-Model Ensemble System for the outer Heliosphere (MMESH)-- a suite of analysis tools designed to improve the accuracy of solar wind propagation models at the outer planets by self-consistently quantifying modeling uncertainties and biases and forming ensemble models with estimated error. Robust ensembles models allow statistically meaningful analyses of the effects of various solar wind drivers on planetary magnetospheres and quantification of the extent of external control over giant planet magnetospheres. We will conclude by demonstrating the usefulness of these statistical techniques by showing early results of an investigation into external control over Jupiter's overall auroral power and discussing future applications and improvements of this technique.

How to cite: Rutala, M. J., Jackman, C. M., Fogg, A. R., Murray, S. A., Owens, M. J., and Tao, C.: The Balance of Internal and External Drivers in Gas Giant Magnetospheres, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19005, https://doi.org/10.5194/egusphere-egu24-19005, 2024.

EGU24-420 | ECS | Orals | ESSI1.5

Neural Networks for Surrogate Models of the Corona and Solar Wind 

Filipa Barros, João José Graça Lima, Rui F. Pinto, and André Restivo

In previous work, an Artificial Neural Network (ANN) was developed to automate the estimation of solar wind profiles used as initial conditions in MULTI-VP simulations. This approach, coupled with profile clustering, reduced the time previously required for estimation by MULTI-VP, enhancing the efficiency of the simulation process. It was observed that generating initial estimates closer to the final simulation led to reduced computation time, with a mean speedup of 1.13. Additionally, this adjustment yielded a twofold advantage: it minimized the amplitude of spurious transients, reinforcing the numerical stability of calculations and enabling the code to maintain a more moderate integration time step.

However, upon further analysis, it became evident that the physical model inherently required a relaxation time for the final solution to stabilize. Therefore, while refining initial conditions offered improvements, there was a limit to how much it could accelerate the process. Consequently, attention turned towards the development of a surrogate model focused on the upper corona (from 3 solar radii to 30 solar radii). This range was chosen because the model can avoid learning the initial phases of wind acceleration, which are hard to accurately predict. Moreover, in order to connect the model to heliospheric models and for space weather applications, more than 3 radii is more than sufficient and guarantees that the physics remain consistent within the reproducible domain.

This surrogate model aims at delivering faster forecasts, with MULTI-VP running in parallel (eventually refining the solutions). The surrogate model for MULTI-VP was tested using a heliospheric model and data from spacecraft at L1, validating its efficacy beyond Mean Squared Error (MSE) evaluations and ensuring physical conservation principles were upheld.

This work aims at simplifying and accelerating the process of establishing boundary conditions for heliospheric models without dismissing the physical models for both extreme events and for more physically accurate results. 

How to cite: Barros, F., Lima, J. J. G., F. Pinto, R., and Restivo, A.: Neural Networks for Surrogate Models of the Corona and Solar Wind, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-420, https://doi.org/10.5194/egusphere-egu24-420, 2024.

we show the evolutions of the separated strands within the apparent single coronal loops observed in Atmospheric Imaging Assembly (AIA) images. The loop strands are detected on  the upsampled AIA 193 equation.pdf images, which are   generated using a super-resolution convolutional neural  network, respectively. The architecture of the network is designed to map the AIA images to unprecedentedly high spatial resolution coronal images taken by  High-resolution Coronal Imager (Hi-C) during its brief flight. At some times, pairs of individual strands appeared to braid with each other and subsequently evolved to become pairs of almost parallel ones with their segments having exchanged totally.  These evolutions provide  morphological evidence supporting occurrences of magnetic reconnections between the braiding strands, which are further confirmed by  the occurrences of the transient hot emissions (>5 MK)  located at the footpoints of  the braiding structures. 

How to cite: Bi, Y.: The coronal braiding structures detected in the machine-learning upscaled SDO/AIA images, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1494, https://doi.org/10.5194/egusphere-egu24-1494, 2024.

EGU24-1604 | ECS | Orals | ESSI1.5

Machine Learning Synthesis and inversion method for Stokes Parameters in the solar context 

Juan Esteban Agudelo Ortiz, Germain Nicolás Morales Suarez, Santiago Vargas Domínguez, and Sergiy Shelyag

The arrival of new and more powerful spectropolarimetric instruments such as DKIST, the development of better magnetohydrodinamic (MHD) simulation codes and the creation of newly inversion methods, are coming with the demands of increasing amounts of computational time and power. This, with increasing generation of data, will come with even years of processing that will stop the advance of scientific investigations on mid-late stages. The arrival of Machine Learning models able to replicate patterns in data come with the possibilites of them to adapt to different types of datasets, such as those for classification or for creation of sequences like the seq2seq models, that once trained, they are able to give results according to previous methods that differ on order of magnitude in time processing, being a lot faster. Some work has been done within this field for creating machine learning inversion methods using data obtained from actual inversion codes applied on observational data, and using data from radiative transfer codes for synthesis, reducing both computational demands and time processing. This work attempts to follow onto this steps, using in this case datasets obtained from simulation codes like MURaM and their correspondent Stokes parameters obtained from non-lte radiative transfer codes like NICOLE, training forward (synthesis) and backward (inversion) some neural network models to test whether or not they can learn their physical behaviours and at what accuracy, for being used in the future to process actual data obtained from newly simulation codes and for real solar observations, being another step into the future for creating a new paradigm on how to invert and sunthesize quantities in Physics in general.

How to cite: Agudelo Ortiz, J. E., Morales Suarez, G. N., Vargas Domínguez, S., and Shelyag, S.: Machine Learning Synthesis and inversion method for Stokes Parameters in the solar context, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1604, https://doi.org/10.5194/egusphere-egu24-1604, 2024.

EGU24-2046 | ECS | Posters on site | ESSI1.5

Comparative Analysis of Random Forest and XGBoost in Classifying Ionospheric Signal Disturbances During Solar Flares 

Filip Arnaut, Aleksandra Kolarski, and Vladimir Srećković

In our previous publication (Arnaut et al. 2023), we demonstrated the application of the Random Forest (RF) algorithm for classifying disturbances associated with solar flares (SF), erroneous signals, and measurement errors in VLF amplitude data i.e., anomaly detection in VLF amplitude data. The RF algorithm is widely regarded as a preferred option for conducting research in novel domains. Its advantages, such as its ability to avoid overfitting data and its simplicity, make it particularly valuable in these situations. Nevertheless, it is imperative to conduct thorough testing and evaluation of alternative algorithms and methods to ascertain their potential advantages and enhance the overall efficiency of the method. This brief communication demonstrates the application of the XGBoost (XGB) method on the exact dataset previously used for the RF algorithm, along with a comparative analysis between the two algorithms. Given that the problem is framed as a machine learning (ML) problem with a focus on the minority class, the comparative analysis is exclusively conducted using the minority (anomalous) data class. The data pre-processing methodology can be found in Arnaut et al. (2023). The XGB tuning process involved using a grid search method to optimize the hyperparameters of the model. The number of estimators (trees) was varied from 25 to 500 in increments of 25, and the learning rate was varied from 0.02 to 0.4 in increments of 0.02. The F1-Score for the anomalous data class is similar for both models, with a value of 0.508 for the RF model and 0.51 for the XGB model. These scores were calculated using the entire test dataset, which consists of 19 transmitter-receiver pairs. Upon closer examination, it becomes evident that the RF model exhibits a higher precision metric (0.488) than the XGB model (0.37), while the XGB model demonstrates a higher recall metric (0.84) compared to the RF model (0.53). Upon examining each individual transmitter-receiver pair, it was found that XGB outperformed RF in terms of F1-Scores in 10 out of 19 cases. The most significant disparities are observed in cases where the XGB model outperformed by a margin of 0.15 in terms of F1-Score, but conversely performed worse by approximately -0.16 in another instance for the anomalous data class. The XGB models outperformed the RF model by approximately 6.72% in terms of the F1-score for the anomalous data class when averaging all the 19 transmitter-receiver pairs. When utilizing a point-based evaluation metric that assigns rewards or penalties for each entry in the confusion matrix, the RF model demonstrates an overall improvement of approximately 5% compared to the XGB model. Overall, the comparison between the RF and XGB models is ambiguous. Both models have instances where one is superior to the other. Further research is necessary to fully optimize the method, which has benefits in automatically classifying VLF amplitude anomalous signals caused by SF effects, erroneous measurements, and other factors.

References:

Arnaut, F., Kolarski, A. and Srećković, V.A., 2023. Random Forest Classification and Ionospheric Response to Solar Flares: Analysis and Validation. Universe9(10), p.436.

How to cite: Arnaut, F., Kolarski, A., and Srećković, V.: Comparative Analysis of Random Forest and XGBoost in Classifying Ionospheric Signal Disturbances During Solar Flares, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2046, https://doi.org/10.5194/egusphere-egu24-2046, 2024.

EGU24-4181 | Posters on site | ESSI1.5

Prediction of sunspot number using Gaussian processes 

Everton Frigo and Italo Gonçalves

The solar activity has various direct and indirect impacts on human activities. During periods of high solar activity, the harmful effects triggered by solar variability are maximized. On a decadal to multidecadal time scale, solar variability exhibits a main cycle of around 11 years known as the Schwabe solar cycle, leading to a solar maximum approximately every 11 years. The most commonly used variable for measuring solar activity is the sunspot number. Over the last few decades, numerous techniques have been employed to predict the time evolution of the solar cycle for subsequent years. Recently, there has been a growing number of studies utilizing machine learning methods to predict solar cycles. One such method is the Gaussian process, which is well-suited for working with small amounts of data and can also provide an uncertainty measure for predictions. In this study, the Gaussian process technique is employed to predict the sunspot number between 2024 and 2050. The dataset used to train and validate the model comprises monthly averages of sunspots relative to the period 1700-2023. According to the results, the current solar cycle, currently at its maximum, is anticipated to last until 2030. The subsequent solar maximum is projected to occur around the end of 2033, with an estimated maximum sunspot number of approximately 150. If this prediction holds true, the next solar cycle's maximum will resemble that observed in the current one.

How to cite: Frigo, E. and Gonçalves, I.: Prediction of sunspot number using Gaussian processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4181, https://doi.org/10.5194/egusphere-egu24-4181, 2024.

EGU24-4471 | ECS | Orals | ESSI1.5

Solar Wind Speed Estimation via Symbolic Knowledge Extraction from Opaque Models 

Federico Sabbatini and Catia Grimani

The unprecedented predictive capabilities of machine learning models make them inestimable tools to perform data forecasting and other complex tasks. Benefits of these predictors are even more precious when there is the necessity of surrogating unavailable data due to the lack of dedicated instrumentation on board space missions. For instance, the future ESA space interferometer LISA for low-frequency gravitational wave detection will host, as part of its diagnostics subsystem, particle detectors to measure the galactic cosmic-ray flux and magnetometers to monitor the magnetic field intensity in the region of the interferometer mirrors. No instrumentation dedicated to the interplanetary medium parameter monitoring will be placed on the three spacecraft constituting the LISA constellation. However, important lessons about the correlation between galactic cosmic-ray flux short-term variations and the solar wind speed profile have been learned with the ESA LISA precursor mission, LISA Pathfinder, orbiting around the L1 Lagrange point. In a previous work, we have demonstrated that for LISA Pathfinder it was possible to reconstruct with an uncertainty of 2 nT the interplanetary magnetic field intensity for interplanetary structure transit monitoring. Machine learning models are proposed here to infer the solar wind speed that is not measured on the three LISA spacecraft from galactic cosmic-ray measurements. This work is precious and necessary since LISA, scheduled to launch in 2035, will trail Earth on the ecliptic at 50 million km distance, too far from the orbits of other space missions dedicated to the interplanetary medium monitoring to benefit of their observations.

We built an interpretable machine learning predictor based on galactic cosmic-ray and interplanetary magnetic field observations to obtain a solar wind speed reconstruction within ±65 km s-1 of uncertainty. Interpretability is achieved by applying the CReEPy symbolic knowledge extractor to the outcomes of a k-NN regressor. The extracted knowledge consists of linear equations aimed at describing the solar wind speed in terms of four statistical indices calculated for the input variables.

Details about the model workflow, performance and validation will be presented at the conference, together with the advantages, drawbacks and possible future enhancements, to demonstrate that our model may provide the LISA mission with an effective and human-interpretable tool to carry out reliable solar wind speed estimates and recognise the transit of interplanetary structures nearby the LISA spacecraft, as a support to the data analysis activity for the monitoring of the external forces acting on the spectrometer mirrors.

How to cite: Sabbatini, F. and Grimani, C.: Solar Wind Speed Estimation via Symbolic Knowledge Extraction from Opaque Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4471, https://doi.org/10.5194/egusphere-egu24-4471, 2024.

EGU24-6558 | ECS | Orals | ESSI1.5

A New Machine Learning Approach for Predicting Extreme Space Weather 

Andong Hu and Enrico Camporeale

We present an innovative method, ProBoost (Probabilistic Boosting), for forecasting extreme space weather events using ensemble machine learning (ML). Ensembles enhance prediction accuracy, but applying them to ML faces challenges as ML models often lack wellcalibrated uncertainty estimates. Moreover, space weather problems are typically affected by very imbalanced datasets (i.e., extreme and rare events) To overcome these difficulties, we developed a method that incorporates uncertainty quantification (UQ) in neural networks, enabling simultaneous forecasting of prediction uncertainty.
Our study applies ProBoost to the following space weather applications:
• One-to-Six-Hour Lead-Time Model: Predicting Disturbance Storm Time (Dst) values using solar wind data.
• Two-Day Lead-Time Model: Forecasting Dst probability using solar images.
• Geoelectric Field Model: Multi-hour lead time, incorporating solar wind and SuperMag data.
• Ambient Solar Wind Velocity Forecast: Up to 5 days ahead.
ProBoost is model-agnostic, making it adaptable to various forecasting applications beyond space weather.

How to cite: Hu, A. and Camporeale, E.: A New Machine Learning Approach for Predicting Extreme Space Weather, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6558, https://doi.org/10.5194/egusphere-egu24-6558, 2024.

We use the framework of Physics-Informed Neural Network (PINN) to solve the inverse problem associated with the Fokker-Planck equation for radiation belts' electron transport, using 4 years of Van Allen Probes data. Traditionally, reduced models have employed a diffusion equation based on the quasilinear approximation. We show that the dynamics of “killer electrons” is described more accurately by a drift-diffusion equation, and that drift is as important as diffusion for nearly-equatorially trapped ∼1 MeV electrons in the inner part of the belt. Moreover, we present a recipe for gleaning physical insight from solving the ill-posed inverse problem of inferring model coefficients from data using PINNs. Furthermore, we derive a parameterization for the diffusion and drift coefficients as a function of L only, which is both simpler and more accurate than earlier models. Finally, we use the PINN technique to develop an automatic event identification method that allows identifying times at which the radial transport assumption is inadequate to describe all the physics of interest.

How to cite: Camporeale, E.: Data-Driven Discovery of Fokker-Planck Equation for the Earth's Radiation Belts Electrons Using Physics-Informed Neural Networks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6899, https://doi.org/10.5194/egusphere-egu24-6899, 2024.

The detection of asteroids involves the processing of sequences of astronomical images. The main challenges arise from the huge volume of data that should be processed in a reasonable amount of time. To address this, we developed the NEARBY platform [1], [2] for efficiently automatic detection of asteroids in sequence of astronomical images. This platform encompasses multidimensional data processing capabilities, human-verified visual analysis, and cloud-based adaptability. This paper outlines the enhancements we have made to this automated asteroid detection system by integrating a machine learning-based classifier known as the CERES module. The integration of the CERES module [3] into the NEARBY platform substantially enhances its performance by automatically reducing the number of false positive detections. Consequently, this leads to a more reliable and efficient system for asteroid identification, while also reducing the time and effort required by human experts to validate detected candidates (asteroids). The experiments highlight these improvements and their significance in advancing the field of asteroid tracking. Additionally, we explore the applicability of the asteroid classification model, initially trained using images from a specific telescope, across different telescopes.

Acknowledgment:

  • This work was supported by a grant of the Romanian Ministry of Education and Research, CCCDI - UEFISCDI, project number PN-III-P2-2.1-PED-2019-0796, within PNCDI III. (the development of the dataset and CNN models)
  • This research was partially supported by the project 38 PFE in the frame of the programme PDI-PFE-CDI 2021.

References:

  • Bacu, V., Sabou, A., Stefanut, T., Gorgan, D., Vaduvescu, O., NEARBY platform for detecting asteroids in astronomical images using cloud-based containerized applications, 2018 IEEE 14th International Conference on Intelligent Computer Communication and Processing (ICCP), pp. 371-376
  • Stefanut, T., Bacu, V., Nandra, C., Balasz, D., Gorgan, D., Vaduvescu, O., NEARBY Platform: Algorithm for automated asteroids detection in astronomical images, 2018 IEEE 14th International Conference on Intelligent Computer Communication and Processing (ICCP), pp. 365-369
  • Bacu, V.; Nandra, C.; Sabou, A.; Stefanut, T.; Gorgan, D. Assessment of Asteroid Classification Using Deep Convolutional Neural Networks. Aerospace 2023, 10, 752. https://doi.org/10.3390/aerospace10090752

 

How to cite: Bacu, V.: Enhancement of the NEARBY automated asteroid detection platform with a machine learning-based classifier, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8018, https://doi.org/10.5194/egusphere-egu24-8018, 2024.

EGU24-9174 | ECS | Orals | ESSI1.5

Enhancing Space Mission Return through On-Board Data Reduction using Unsupervised Machine Learning 

Salome Gruchola, Peter Keresztes Schmidt, Marek Tulej, Andreas Riedo, Klaus Mezger, and Peter Wurz

The efficient use of the provided downlink capacity for scientific data is a fundamental aspect of space exploration. The use thereof can be optimised through sophisticated data reduction techniques and automation of processes on board that otherwise require interaction with the operations centres on Earth. Machine learning-based autonomous methods serve both purposes; yet space-based ML applications remain relatively rare compared to the application of ML on Earth to data acquired in space.

In this contribution, we present a potential application of unsupervised machine learning to cluster mass spectrometric data on-board a spacecraft. Data were acquired from a phoscorite rock [1] using a prototype of a laser ablation ionisation mass spectrometer (LIMS) for space research [2]. Two unsupervised dimensionality reduction algorithms, UMAP and densMAP [3,4], were employed to construct low-dimensional representations of the data. Clusters corresponding to different mineral phases within these embeddings were found using HDBSCAN [5]. The impact of data pre-processing and model parameter selection on the classification outcome was investigated through varying levels of pre-processing and extensive grid searches.

Both UMAP and densMAP effectively isolated major mineral phases present within the rock sample, but densMAP additionally found minor inclusions present only in a small number of mass spectra. However, densMAP exhibited higher sensitivity to data pre-processing, yielding lower scores for minimally treated data compared to UMAP. For highly processed data, both UMAP and densMAP exhibited high stability across a broad model parameter space.

Given that the data were recorded using a miniature mass spectrometric instrument designed for space flight, these methods demonstrate effective strategies for substantial reduction of data similarly to what is anticipated on future space missions. Autonomous clustering of data into groups of different chemical composition, followed by the downlink of a representative mass spectrum of each cluster, aids in identifying relevant data. Mission return can therefore be enhanced through the selective downlink of data of interest. As both UMAP and densMAP, coupled with HDBSCAN, are relatively complex algorithms compared to more traditional techniques, such as k-means, it is important to evaluate the benefits and drawbacks of using simpler methods on-board spacecraft.

 

[1] Tulej, M. et al., 2022, https://doi.org/10.3390/universe8080410.

[2] Riedo, A. et al., 2012, https://doi.org/10.1002/jms.3104.

[3] McInnes, L. et al., 2018, https://doi.org/10.48550/arXiv.1802.03426.

[4] Narayan, A., et al., 2021, https://doi.org/10.1038/s41587-020-00801-7.

[5] McInnes, L., et al., 2017, https://doi.org/10.21105/JOSS.00205.

How to cite: Gruchola, S., Keresztes Schmidt, P., Tulej, M., Riedo, A., Mezger, K., and Wurz, P.: Enhancing Space Mission Return through On-Board Data Reduction using Unsupervised Machine Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9174, https://doi.org/10.5194/egusphere-egu24-9174, 2024.

EGU24-10715 | ECS | Posters on site | ESSI1.5

Physics-driven feature combination for an explainable AI approach to flare forecasting 

Margherita Lampani, Sabrina Guastavino, Michele Piana, Federico Benvenuto, and Anna Maria Massone

Typical supervised feature-based machine learning approaches to flare forecasting rely on descriptors extracted from magnetograms, as from Helioseismic and Magnetic Imager (HMI) images, and standardized before being used in the training phase of the machine learning pipeline. However, this artificial intelligence (AI) model does not take into account the physical nature of the features and their role in the plasma physics equations. This talk proposes to generate novel features according to simple physics-driven combinations of the original descriptors, and to show whether this original physically explainable AI model leads to a more predictive solar flare forecasting.

How to cite: Lampani, M., Guastavino, S., Piana, M., Benvenuto, F., and Massone, A. M.: Physics-driven feature combination for an explainable AI approach to flare forecasting, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10715, https://doi.org/10.5194/egusphere-egu24-10715, 2024.

EGU24-12885 | ECS | Posters on site | ESSI1.5

Finding Hidden Conjunctions in the Solar Wind 

Zoe Faes, Laura Hayes, Daniel Müller, and Andrew Walsh

This study aims to identify sets of in-situ measurements of the solar wind which sample the same volume of plasma at different times and locations as it travels through the heliosphere using ensemble machine learning methods. Multiple observations of a single volume of plasma by different spacecraft - referred to here as conjunctions - are becoming more frequent in the current “golden age of heliophysics research” and are key to characterizing the expansion of the solar wind. Specifically, identifying these related observations will enable us to test the current understanding of solar wind acceleration from the corona to the inner heliosphere with a more comprehensive set of measurements than has been used in previous analyses.

Using in-situ measurements of the background solar wind from Solar Orbiter, Parker Solar Probe, STEREO-A, Wind and BepiColombo, we identify a set of criteria based on features of magnetic field, velocity, density and temperature timeseries of known conjunctions and search for other instances for which the criteria are satisfied, to find previously unknown conjunctions. We use an ensemble of models, including random forests and recurrent neural networks with long short-term memory trained on synthetic observations obtained from magnetohydrodynamic simulations, to identify candidate conjunctions solely from kinetic properties of the solar wind. Initial results show a previously unidentified set of conjunctions between the spacecraft considered in this study. While this analysis has thus far only been performed on observations obtained since 2021 (start of Solar Orbiter science operations), the methods used here can be applied to other datasets to increase the potential for scientific return of existing and future heliophysics missions.

The modular scientific software built over the course of this research includes methods for the retrieval, processing, visualisation, and analysis of observational and synthetic timeseries of solar wind properties. It also includes methods for feature engineering and integration with widely used machine learning libraries. The software is available as an open-source Python package to ensure results can be easily reproduced and to facilitate further investigation of coordinated in-situ data in heliophysics.

How to cite: Faes, Z., Hayes, L., Müller, D., and Walsh, A.: Finding Hidden Conjunctions in the Solar Wind, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12885, https://doi.org/10.5194/egusphere-egu24-12885, 2024.

EGU24-12961 | ECS | Posters on site | ESSI1.5

Physics-informed neural networks for advanced solar magnetic field extrapolations 

Robert Jarolim, Benoit Tremblay, Matthias Rempel, Julia Thalmann, Astrid Veronig, Momchil Molnar, and Tatiana Podladchikova

Physics-informed neural networks (PINNs) provide a novel approach for data-driven numerical simulations, tackling challenges of discretization and enabling seamless integration of noisy data and physical models (e.g., partial differential equations). In this presentation, we discuss the results of our recent studies where we apply PINNs for coronal magnetic field extrapolations of the solar atmosphere, which are essential to understand the genesis and initiation of solar eruptions and to predict the occurrence of high-energy events from our Sun.
We utilize our PINN to estimate the 3D coronal magnetic fields based on photospheric vector magnetograms and the force-free physical model. This approach provides state-of-the-art coronal magnetic field extrapolations in quasi real-time. We simulate the evolution of Active Region NOAA 11158 over 5 continuous days, where the derived time profile of the free magnetic energy unambiguously relates to the observed flare activity.
We extend this approach by utilizing multi-height magnetic field measurements and combine them in a single magnetic field model. Our evaluation shows that the additional chromospheric field information leads to a more realistic approximation of the solar coronal magnetic field. In addition, our method intrinsically provides an estimate of the height corrugation of the observed magnetograms.
We provide an outlook on our ongoing work where we use PINNs for global force-free magnetic field extrapolations. This approach enables a novel understanding of the global magnetic topology with a realistic treatment of current carrying fields.
In summary, PINNs have the potential to greatly advance the field of numerical simulations, accelerate scientific research, and enable advanced space weather monitoring.

How to cite: Jarolim, R., Tremblay, B., Rempel, M., Thalmann, J., Veronig, A., Molnar, M., and Podladchikova, T.: Physics-informed neural networks for advanced solar magnetic field extrapolations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12961, https://doi.org/10.5194/egusphere-egu24-12961, 2024.

EGU24-14186 | Posters on site | ESSI1.5

Near real-time construction of Solar Coronal Parameters based on MAS simulation by Deep Learning  

Sumiaya Rahman, Hyun-Jin Jeong, Ashraf Siddique, and Yong-Jae Moon

Magnetohydrodynamic (MHD) models provide a quantitative 3D distribution of the solar corona parameters (density, radial velocity, and temperature). However, this process is expensive and time-consuming. For this, we apply deep learning models to reproduce the 3D distribution of solar coronal parameters from 2D synoptic photospheric magnetic fields. We consider synoptic photospheric magnetic fields as an input to obtain 3D solar coronal parameters simulated by the MHD Algorithm outside a Sphere (MAS) from June 2010 to January 2023. Each parameter is individually trained using 150 deep learning models, corresponding to 150 solar radial distances ranging from 1 to 30 solar radii. Our study yields significant findings. Firstly, our model accurately reproduces 3D coronal parameter structures across the 1 to 30 solar radii range, demonstrating an average correlation coefficient value of approximately 0.96. Secondly, the 150 deep-learning models exhibit a remarkably shorter runtime (about 16 seconds for each parameter), with an NVIDIA Titan XP GPU, in comparison to the conventional MAS simulation time. As the MAS simulation is a regularization model, we may significantly reduce the simulation time by using our results as an initial magnetic configuration to obtain an equilibrium condition. In the future, we hope that the generated solar coronal parameters can be used for near real-time forecasting of heliospheric propagation of solar eruptions.

How to cite: Rahman, S., Jeong, H.-J., Siddique, A., and Moon, Y.-J.: Near real-time construction of Solar Coronal Parameters based on MAS simulation by Deep Learning , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14186, https://doi.org/10.5194/egusphere-egu24-14186, 2024.

EGU24-15813 | ECS | Orals | ESSI1.5

Instrument-to-Instrument translation: An AI tool to intercalibrate, enhance and super-resolve solar observations 

Christoph Schirninger, Astrid Veronig, Robert Jarolim, J. Emmanuel Johnson, Anna Jungbluth, Richard Galvez, Lilli Freischem, and Anne Spalding

Various instruments are used to study the Sun, including ground-based observatories and space telescopes. These data products are constantly changing due to technological improvements, different instrumentation, or atmospheric effects. However, for certain applications such as ground-based solar image reconstruction or solar cycle studies, enhanced and combined data products are necessary.

We present a general AI tool called Instrument-to-Instrument (ITI; Jarolim et al. 2023) translation, which is capable of translating datasets between two different image domains. This approach enables instrument intercalibration, image enhancement, mitigation of quality degradations, and super-resolution across multiple wavelength bands. The tool is built on unpaired image-to-image translation, which enables a wide range of applications, where no spatial or temporal overlap is required between the considered datasets.

In this presentation, we highlight ITI as a general tool for Heliospheric applications and demonstrate its capabilities by applying it to data from Solar Orbiter/EUI, PROBA2/SWAP, and the Solar Dynamics Observatory/AIA in order to achieve a homogenous, machine-learning ready dataset that combines three different EUV imagers. 

The direct comparison of aligned observations shows the close relation of ITI-enhanced and real high-quality observations. The evaluation of light-curves demonstrates an improved inter-calibration.

ITI is provided open-source to the community  and can be easily applied to novel datasets and various research applications. 

This research is funded through a NASA 22-MDRAIT22-0018 award (No 80NSSC23K1045) and managed by Trillium Technologies, Inc (trillium.tech)

How to cite: Schirninger, C., Veronig, A., Jarolim, R., Johnson, J. E., Jungbluth, A., Galvez, R., Freischem, L., and Spalding, A.: Instrument-to-Instrument translation: An AI tool to intercalibrate, enhance and super-resolve solar observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15813, https://doi.org/10.5194/egusphere-egu24-15813, 2024.

EGU24-15981 | ECS | Posters on site | ESSI1.5

Addressing the closure problem using supervised Machine Learning 

Sophia Köhne, Brecht Laperre, Jorge Amaya, Sara Jamal, Simon Lautenbach, Rainer Grauer, Giovanni Lapenta, and Maria Elena Innocenti

When deriving fluid equations from the Vlasov equation for collisionless plasmas, one runs into the so-called closure problem: each equation for the temporal evolution of one particle moment (density, current, pressure, heat flux, …) includes terms depending on the next order moment. Therefore, when choosing to truncate the description at the nth order, one must approximate the terms related to the (n+1)th order moment included in the evolution equation for the nth order moment. The order at which the hierarchy is closed and the assumption behind the approximations used determine how accurately a fluid description can reproduce kinetic processes.

In this work, we aim at reconstructing specific particle moments from kinetic simulations, using as input the electric and magnetic field and the lower moments. We use fully kinetic Particle In Cell simulations, where all physical information is available, as the ground truth. The approach we present here uses supervised machine learning to enable a neural network to learn how to reconstruct higher moments from lower moments and fields.

Starting from the work of Laperre et al., 2022 we built a framework which makes it possible to train feedforward multilayer perceptrons on kinetic simulations to learn to predict the higher moments of the Vlasov equation from the lower moments, which would also be available in fluid simulations. We train on simulations of magnetic reconnection in a double Harris current sheet with varying background guide field obtained with the semi-implicit Particle-in-Cell code iPiC3D (Markidis et al, 2010). We test the influence of data preprocessing techniques, of (hyper-)parameter variations and of different architectures of the neural networks on the quality of the predictions that are produced. Furthermore, we investigate which metrics are most useful to evaluate the quality of the outcome.

How to cite: Köhne, S., Laperre, B., Amaya, J., Jamal, S., Lautenbach, S., Grauer, R., Lapenta, G., and Innocenti, M. E.: Addressing the closure problem using supervised Machine Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15981, https://doi.org/10.5194/egusphere-egu24-15981, 2024.

EGU24-18534 | ECS | Posters on site | ESSI1.5

Visualizing three years of STIX X-ray flare observations using self-supervised learning 

Mariia Drozdova, Vitaliy Kinakh, Francesco Ramunno, Erica Lastufka, and Slava Voloshynovskiy

Operating continuously for over three years, Solar Orbiter's STIX has observed more than 43 thousand X-ray flares. This study presents a compelling visualization of this publicly available database, using self-supervised learning to organize reconstructed flare images by their visual properties. Networks designed for self-supervised learning, such as Masked Siamese Networks or Autoencoders, are able to learn latent space embeddings which encode core characteristics of the data. We investigate the effectiveness of various pre-trained vision models, fine-tuning strategies, and image preparation. This visual representation offers a valuable starting point for identifying interesting events and grouping flares based on shared morphological characteristics, useful for conducting statistical studies or finding unique flares in this rich set of observations.

How to cite: Drozdova, M., Kinakh, V., Ramunno, F., Lastufka, E., and Voloshynovskiy, S.: Visualizing three years of STIX X-ray flare observations using self-supervised learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18534, https://doi.org/10.5194/egusphere-egu24-18534, 2024.

EGU24-19248 | Posters on site | ESSI1.5

Segmentation and Tracking of Solar Eruptive Phenomena with Convolutional Neural Networks (CNN) 

Oleg Stepanyuk and Kamen Kozarev

Solar eruptive events are complex phenomena, which most often include coronal mass ejections (CME), flares, compressive/shock waves, and filament eruptions. CMEs are large eruptions of magnetized plasma from the Sun’s outer atmosphere or corona, that propagate outward into the interplanetary space. Solar Energetic Particles (SEP) are produced through particle acceleration in flares or CME-driven shocks. Exact mechanisms behind SEP production are yet to be understood, but it is thought that most of their acceleration occurs in shocks starting in the low corona. Over the last several decades a large amount of remote solar eruption observations have become available from ground-based and space-borne instruments. This has required the development of software approaches for automated characterization of eruptive features. Most solar feature detection and tracking algorithms currently in use have restricted applicability and complicated processing chains, while the complexities in engineering machine learning (ML) training sets limit the use of data-driven approaches for tracking or solar eruptive related phenomena. Recently, we introduced a hybrid algorithmic—data driven approach for characterization and tracking of solar eruptive features with the improved wavelet-based, multi-instrument Wavetrack package (Stepanyuk et.al, J. Space Weather Space Clim. (2024)), which was used to produce training datasets for data driven image segmentation with convolutional neural networks (CNN). Its perfomance was shown on a limited set of SDO AIA 193A instrument data perfoming segmentation of EUV and shock waves. Here we extend this approach and present an ensemble of more general CNN models for data-driven segmentation of various eruptive phenomena for the set of ground-based and remote instruments data. We discuss our approach to engineering training sets and data augmentation, CNN topology and training techniques. 

How to cite: Stepanyuk, O. and Kozarev, K.: Segmentation and Tracking of Solar Eruptive Phenomena with Convolutional Neural Networks (CNN), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19248, https://doi.org/10.5194/egusphere-egu24-19248, 2024.

EGU24-19558 | Orals | ESSI1.5

Comparative Analysis of Data Preprocessing Methods for Precise Orbit Determination 

Tom Andert, Benedikt Aigner, Fabian Dallinger, Benjamin Haser, Martin Pätzold, and Matthias Hahn

In Precise Orbit Determination (POD), employing proper methods for pre-processing tracking data is crucial not only to mitigate data noise but also to identify potential unmodeled effects that may elude the prediction model of the POD algorithm. Unaccounted effects can skew parameter estimation, causing certain parameters to assimilate the unmodeled effects and deviate from their true values. Therefore, enhancing the pre-processing of tracking data ultimately contributes to refining the prediction model.

The Rosetta spacecraft, during its two-year mission alongside comet 67P/Churyumov-Gerasimenko, collected a substantial dataset of tracking data. In addition to this data, also tracking data from the Mars Express spacecraft, orbiting Mars since 2004, will serve as a use case to assess and compare diverse data pre-processing methods. Both traditional and AI-based techniques are explored to examine the impact of various strategies on the accuracy of orbit determination. This aims to enhance POD, thereby yielding a more robust scientific outcome.

How to cite: Andert, T., Aigner, B., Dallinger, F., Haser, B., Pätzold, M., and Hahn, M.: Comparative Analysis of Data Preprocessing Methods for Precise Orbit Determination, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19558, https://doi.org/10.5194/egusphere-egu24-19558, 2024.

EGU24-21463 | ECS | Posters on site | ESSI1.5

A machine learning approach to meteor light curve analysis 

Lucas Mandl, Apostolous Christou, and Andreas Windisch

In this work we conduct a thorough examination of utilizing machine learning and computer
vision techniques for classifying meteors based on their characteristics. The focus of the re-
search is the analysis of light curves emitted by meteors as they pass through the Earth’s atmo-
sphere, including aspects such as luminosity, duration, and shape. Through extracting features
from these light curves and comparing them to established meteors orbits, valuable informa-
tion about the meteor’s origin and chemical composition is sought to be obtained. A significant
contribution of the thesis is the development of methods for classifying meteors by extracting
features from the light curve shape through the usage of unsupervised classification algorithms.
This approach allows for the automatic classification of meteors into various groups based on
their properties. Data for the research is collected by a three-camera setup at the Armagh observatory,
comprising one medium-angle camera and
two wide-angle cameras. This setup enables the capturing of detailed images of meteor light
curves, as well as various other observations such as coordinate and angular data. The research
also involves the use of machine learning algorithms for data reduction and classification tasks.
By applying these techniques to the data collected from the camera setup, the identification of
parent objects based on chemical composition and meteor path is facilitated, along with the
acquisition of other valuable information about the meteors.

How to cite: Mandl, L., Christou, A., and Windisch, A.: A machine learning approach to meteor light curve analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21463, https://doi.org/10.5194/egusphere-egu24-21463, 2024.

ST2 – Magnetosphere

EGU24-712 | Orals | ST2.1 | Highlight

Metals in Earth’s Magnetosphere: From Ionosphere or Moon?  

Mei-Yun Lin and Andrew Poppe

Recent observations by the Geotail and Cluster missions in the magnetosphere have revealed the presence of singly charged metallic ions, such as Mg+ and Fe+. However, the origins and transport mechanisms of these metallic ions are unknown. Metallic ions are prevalent in the Earth's lower atmosphere, primarily produced from the ablation of meteoroids and the formation of metal layers. Similarly, metallic ions are also common in the vicinity of the Moon's surface, where they are created from the ionization of the lunar exosphere, a thin neutral atmosphere that surrounds the Moon. To deepen our understanding of the sources of the metallic ions in the magnetosphere, this study develops different strategies to evaluate the contributions of metallic ion outflow from the ionosphere and the Moon across different solar and geomagnetic conditions. 

 

To estimate the metallic ion outflow from the ionosphere, we utilize a physics-based model, PWOM, which solves the transport of ionospheric outflow for all the relevant ion species, such as H+, He+, N+, O+, and molecular ions. As metallic ions are mainly produced via charge exchange between molecular ions and metal atoms in the ionosphere, the abundance of metallic ion outflow is represented by the densities of molecular ions with adjusted ratios. In addition, the metallic ion upflow will be further accelerated to outflow in the high-altitude ionosphere via the energization of wave-particle interaction. This vertical transport of metallic ions is further tracked by PWOM and shows a strong connection with the wave energy input.

 

On the other hand, metallic ion outflow from the Moon is inferred from LADEE and ARTEMIS observational data. These pickup ions are generated through charge exchange or electron impact from the metallic neutrals, which are primarily produced through either charged particle sputtering or micrometeoroid impact vaporization of the lunar surface. The abundances of metallic neutrals are derived from information on sputter yields and observed ion fluxes. Once the densities of neutral metal species are obtained, the metallic pickup ion fluxes are further calculated based on the relevant ionization cross sections with incoming electron and ion fluxes to the lunar exosphere. We use in-situ ARTEMIS observations of ion and electron fluxes to properly calculate these ionization rates. 

 

This study will be the first to compare the contributions of ionospheric outflow and lunar pickup ions to the magnetosphere. Moreover, by utilizing observational data from ARTEMIS, the variations of sources of metallic ions will be analyzed as the Moon passes through the upstream solar wind, magnetosheath, and magnetotail. The differences between the outflow of metallic ions from the ionosphere and the Moon can be used as a tracer to better understand the transport and energization processes of heavy ion plasma in the magnetosphere. 

How to cite: Lin, M.-Y. and Poppe, A.: Metals in Earth’s Magnetosphere: From Ionosphere or Moon? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-712, https://doi.org/10.5194/egusphere-egu24-712, 2024.

EGU24-1530 | ECS | Orals | ST2.1

Modeling soft X-ray emissions at the dayside magnetopause 

Qiuyu Xu, Dimitra Koutroumpa, Ronan Modolo, Tianran Sun, Hyunju Connor, and Steve Sembay

In this study, we simulate the Solar Wind Charge Exchange (SWCX) soft X-ray emissions at dayside magnetopause by using magnetohydrodynamic (MHD) and Test-Particle (TP) models. Due to the single fluid description, the MHD model is unable to resolve the particle kinetic effects or distinguish the magnetospheric plasma and the solar wind plasma. We investigate these effects with the TP model. As the TP model does not self-compute magnetic and electric field, the magnetic and electric field data obtained from OpenGGCM and PPMLR MHD model are used as the input to TP model. The soft X-ray emissivity maps simulated from pure OpenGGCM and PPMLR MHD approaches and from TP-OpenGGCM and TP-PPMLR MHD approaches are presented and compared. The results indicate that the TP model can well resolve the kinetic effects and the individual spectral characteristics, and it does not require a masking method in the magnetosphere. Therefore the TP model is a complementary approach for simulating the X-ray emissions in the dayside magnetosheath and cusps.

How to cite: Xu, Q., Koutroumpa, D., Modolo, R., Sun, T., Connor, H., and Sembay, S.: Modeling soft X-ray emissions at the dayside magnetopause, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1530, https://doi.org/10.5194/egusphere-egu24-1530, 2024.

EGU24-1778 | ECS | Posters on site | ST2.1

Studying the Earth's magnetopause at High Latitudes With CLUSTER 

Niklas Grimmich, Ferdinand Plaschke, C. Philippe Escoubet, Martin O. Archer, Rumi Nakamura, David G. Sibeck, and O. Dragos Constantinescu

The boundary between the interplanetary magnetic field and the terrestrial magnetic field is the magnetopause. This magnetopause is influenced by dynamic changes in the solar wind, i.e. different solar wind conditions lead to a change in the shape and location of the magnetopause. The interaction between the solar wind and the magnetosphere can be studied from in-situ spacecraft observations. Many studies focus on the equatorial plane, as this is where recent spacecraft constellations such as THEMIS or MMS operate. However, to fully capture the interaction, it is important to study the high latitude regions as well. The Cluster spacecraft allow us to collect a database of high-latitude magnetopause crossings and study magnetopause motion in this region, as well as deviations from established magnetopause models. We use multi-spacecraft analysis tools to investigate the direction of magnetopause motion in the high latitudes and compare the occurrence of crossings at different locations with the result in the equatorial plane. Our results will be useful for the interpretation of plasma measurements from the upcoming SMILE mission, as this spacecraft will also fly frequently through the high-latitude magnetopause.

How to cite: Grimmich, N., Plaschke, F., Escoubet, C. P., Archer, M. O., Nakamura, R., Sibeck, D. G., and Constantinescu, O. D.: Studying the Earth's magnetopause at High Latitudes With CLUSTER, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1778, https://doi.org/10.5194/egusphere-egu24-1778, 2024.

EGU24-1968 | Posters on site | ST2.1

Reproducing the magnetospheric response to southward turnings in MHD simulations 

Andrey Samsonov, Stephen Milan, Tianran Sun, Natalia Buzulukova, Jacobo Varela, and Colin Forsyth

State-of-the-art numerical models have been developed to reproduce magnetospheric dynamics in response to solar wind variations. However, we do not understand how accurate the predictions of the models would be in different solar wind and magnetospheric conditions. In this study, we consider the two relatively simple cases with southward interplanetary magnetic field turnings which have been simulated by several MHD models (SWMF, LFM, PPMLR-MHD, PLUTO). We compare numerical results with observations in terms of global magnetospheric characteristics such as the polar cap open flux and the indices of magnetospheric activity. Our purpose is to understand why some models can make better predictions. To answer this question we also compare the results of the same MHD model with different numerical resolutions and ionospheric conductances and show that both resolution and conductance are important for accurate predictions. By comparing simulations with observations, we can figure out the optimal parameters in the models which should be used in the future.

How to cite: Samsonov, A., Milan, S., Sun, T., Buzulukova, N., Varela, J., and Forsyth, C.: Reproducing the magnetospheric response to southward turnings in MHD simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1968, https://doi.org/10.5194/egusphere-egu24-1968, 2024.

EGU24-1994 | ECS | Orals | ST2.1

Flapping Motion Configurations of Geomagnetotail Current Sheet 

Peng Shao and Chao Shen

We explore the geometry of the flapping motion of geomagnetotail current sheet with the magnetic measurements of the Cluster (constellation) using a newly developed technique. The principal curvatures and directions of the surfaces of the flapping current sheet are successfully deduced by the normal field analysis (NFA). Results show that the directions with the minimum curvature of surfaces of flapping motion are approximately along the Sun-Earth line, while the ones with maximum curvature are mostly in the dawn-dusk plane. It is confirmed that the tail flapping motion is a wave arising in the Y-Z plane, but not bend along the Sun-Earth line. Furthermore, our calculations reveal that the maximum curvature radius of the flapping current sheet's surface along the X-axis is on the order of several dozen Earth radii. This implies that the flapping motion extends spatially over a range from several to a dozen Earth radii along the Sun-Earth direction.

How to cite: Shao, P. and Shen, C.: Flapping Motion Configurations of Geomagnetotail Current Sheet, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1994, https://doi.org/10.5194/egusphere-egu24-1994, 2024.

EGU24-2051 | Orals | ST2.1

3D Structure of the Magnetosheath Jets: Global Hybrid-Kinetic Simulations. 

Shahab Fatemi, Maria Hamrin, Eva Krämer, Herbert Gunell, Gabriella Nordin, Tomas Karlsson, and Oleksandr Goncharov

Over the past 25 years, several spacecraft have observed localized, high-pressure regions that sporadically appear in Earth’s magnetosheath, known as the “magnetosheath jets”. Despite previous analyses, the nature of these transient events remains elusive, marked by a range of uncertainties. These uncertainties mainly stem from the fact that oversimplified assumptions have been made in earlier analyses, where the jets are often portrayed as basic cylinder-like structures. This simplification is primarily because of two reasons: First, spacecraft observations in specific magnetosheath locations couldn't comprehensively cover and explore large spatial areas, providing only a limited perspective on the jets. Second, previous models used to study magnetosheath jets were either two-dimensional (2D) spatial models or three-dimensional (3D) with reduced scales of the Earth's magnetosphere to minimize computational complexity when dealing with Earth.

In this study, we use Amitis, a high-performance, three-dimensional (3D in both configuration and velocity spaces), time-dependent hybrid-kinetic plasma model (kinetic ions, fluid electrons) that runs in parallel on Graphics Processing Units (GPUs). We present, for the first time, the global kinetic interaction between the solar wind and the entire magnetosphere of Earth using its true scales. Achieving this level of accuracy in kinetic modeling of the solar wind plasma interaction with Earth has been a long-standing challenge. Our 3D, time-dependent hybrid-kinetic simulations dispel the notion that the magnetosheath jets are simple cylinders. Instead, our simulations show that the magnetosheath jets exhibit complex and interconnected structures with dynamic 3D characteristics. As they move through the magnetosheath, they wrinkle, fold, merge, and split in complex ways before a subset reaches the magnetopause. Our findings are pivotal in advancing our understanding of magnetosheath jets and their significance in coupling between the solar wind and Earth's magnetosphere.

How to cite: Fatemi, S., Hamrin, M., Krämer, E., Gunell, H., Nordin, G., Karlsson, T., and Goncharov, O.: 3D Structure of the Magnetosheath Jets: Global Hybrid-Kinetic Simulations., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2051, https://doi.org/10.5194/egusphere-egu24-2051, 2024.

EGU24-2058 | Orals | ST2.1 | Highlight

Magnetospheric Auroral Asymmetry eXplorer: observing the auroral to uncover how energy flows in space - A Phase A SMEX Mission concept 

Alexa Halford, Michael Liemohn, Aaron Ridley, Daniel Welling, Thomas Immel, Hyunju Connor, Anna DeJong, Gerard Fasel, Christine Gabrielse, Katherine Garcia-Sage, Brian Harding, Emma Spanswick, Shasha Zoe, and Elizabeth MacDonald

The Magnetospheric Auroral Asymmetry Explorer (MAAX) mission concept makes a significant leap in determining how magnetosphere-ionosphere electrodynamic coupling regulates multi-scale energy flow through the near-Earth space environment. Recently selected for a competitive Phase A mission concept study for NASA's Heliophysics Small Explorer program, MAAX accomplishes this by:

  • Understanding how seasons and tilt of the magnetic field regulate energy flow from the solar wind through the geospace system.
  • Discovering how the auroral background conductance governs the formation, evolution, and interhemispheric asymmetries of nightside meso-scale auroral features.
  • Determining how the time-dependent magnetospheric energy flow controls multi-scale auroral dynamics.

The solar wind energy enters the magnetosphere mainly through dayside reconnection. It is stored in the magnetospheric lobes, released in the tail, converted to plasma thermal and kinetic energies. The dynamic processes in the nightside magnetosphere map from the magnetosphere to the ionosphere, resulting in auroral structures. Observations of the aurora have been used as a window to probe and understand these dynamics even beyond the Earth system. The magnetic field lines in which the aurora occurs thread through both hemispheres. Traditionally, auroral observations from one hemisphere are assumed to be conjugate, while limited observations suggest this may not always be applicable. Thus, we can only understand some of the processes that control energy flow through the system from one hemisphere. With observations in both hemispheres, we gain a deeper understanding of the dynamics of this integrated system. MAAX comprises two observatories in circular polar orbits at 20,850 km altitude to view the two auroral ovals. Each satellite carries a high-heritage UV imager that operates poleward of +/-35° latitude. For the mission's 1st year, the observatories are spaced at 90° to allow continuous coverage of each oval with a 6-hour duty cycle. This phase also provides intervals in which both view the same hemisphere or the exact longitude but different hemispheres. For the 2nd year of the mission, the observatories are spaced at 180° to have simultaneous complete viewing of both auroral ovals with a 4.5 hr/1.5 hr on/off duty cycle. Discussed here are the scientific motivations of the mission concepts.

How to cite: Halford, A., Liemohn, M., Ridley, A., Welling, D., Immel, T., Connor, H., DeJong, A., Fasel, G., Gabrielse, C., Garcia-Sage, K., Harding, B., Spanswick, E., Zoe, S., and MacDonald, E.: Magnetospheric Auroral Asymmetry eXplorer: observing the auroral to uncover how energy flows in space - A Phase A SMEX Mission concept, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2058, https://doi.org/10.5194/egusphere-egu24-2058, 2024.

EGU24-2428 | ECS | Posters on site | ST2.1

Pc 4 Cavity mode wave frequency variation associated with inward motion of the magnetopause during interplanetary shock compression 

Dianjun Zhang, Wenlong Liu, Zhao Zhang, Xinlin Li, Theodore Sarris, Jerry Goldstein, and Rezvov Dmitry

A cavity mode wave, referring to a trapped or radially standing fast mode wave between different magnetospheric boundaries, has been developed in theory and reported in observation studies. In this study, we present an interplanetary shock (IPS)-induced cavity mode wave event observed outside the plasmasphere on 31 August 2017 with multispacecraft measurements. The phase delay of 90 degrees between the azimuthal electric field and compressional magnetic field indicates that the fast-mode wave triggered by the IPS is a standing wave, presumably radially trapped in the cavity between the magnetopause and plasmapause. Taking advantage of the location of VAP-B spacecraft right outside the plasmapause and the AARI ground-based high-latitude array mapped in the noon sector, it is suggested that the observed compressional wave associates to cavity mode with its inner boundary at the plasmapause and its outer boundary at the magnetopause. The peak frequency of the wavelet spectrum of the compressional magnetic field increases from 10.5 to 12.5 mHz, which is consistent with the theoretically calculated cavity eigenfrequencies before and after the IPS. We also provide the first evidence that the peak frequency of the cavity mode increases due to the inward motion of the magnetopause during IPS compression.

How to cite: Zhang, D., Liu, W., Zhang, Z., Li, X., Sarris, T., Goldstein, J., and Dmitry, R.: Pc 4 Cavity mode wave frequency variation associated with inward motion of the magnetopause during interplanetary shock compression, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2428, https://doi.org/10.5194/egusphere-egu24-2428, 2024.

EGU24-2677 | Orals | ST2.1

Electron Scale Coherent Structure as Micro Accelerator in the Earth’s Magnetosheath 

Zikang Xie, Qiu-Gang Zong, Chao Yue, Xu-Zhi Zhou, Zhi-Yang Liu, Jian-Sen He, Yi-Xin Hao, Chung-Sang Ng, Hui Zhang, Shu-Tao Yao, Craig J. Pollock, Guan Le, Robert E. Ergun, and Per-Arne Lindqvist

Turbulent energy dissipation is a fundamental process in plasma physics that has not been settled. It is generally believed that the turbulent energy is dissipated at electron scales leading to electron energization in magnetized plasmas. Here, we propose a micro accelerator which could transform electrons from isotropic distribution to trapped, and then to stream (Strahl) distribution. From the MMS observations of an electron-scale coherent structure in the dayside magnetosheath, we identify an electron flux enhancement region in this structure collocated with an increase of magnetic field strength, which is also closely associated with a non-zero parallel electric field. We propose a trapping model considering a field-aligned electric potential together with the mirror force. The results are consistent with the observed electron fluxes from ~50 eV to ~200 eV. It further demonstrates that bidirectional electron jets can be formed by the hourglass-like magnetic configuration of the structure.

How to cite: Xie, Z., Zong, Q.-G., Yue, C., Zhou, X.-Z., Liu, Z.-Y., He, J.-S., Hao, Y.-X., Ng, C.-S., Zhang, H., Yao, S.-T., Pollock, C. J., Le, G., Ergun, R. E., and Lindqvist, P.-A.: Electron Scale Coherent Structure as Micro Accelerator in the Earth’s Magnetosheath, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2677, https://doi.org/10.5194/egusphere-egu24-2677, 2024.

EGU24-2835 | Orals | ST2.1

Conformal mapping for the magnetosheath modeling problems 

Yasuhito Narita, Daniel Schmid, and Henry Holzkamp

Determining the plasma flow and magnetic field in the terrestrial and planetary magnetosheath region is a challenge both in theoretical and observational studies in space plasma physics. We are motivated by the discovery of the Kobel-Flückiger exact solution for the Laplace equation to the scalar shielding potential for the parabolic geometry of the magnetosheath, and develop a novel algorithm of the conformal mapping to exactly transform the Kobel-Flückiger scalar potential onto a user-specified, arbitrary geometry of the magnetosheath. The algorithm starts with the outer and innter boundary models (e.g., bow shock and magnetopause locations in the case of planetary magnetospheres). The shell variable v is constructed by smoothly interpolating between the two boundaries, and the connector variable u (connecting between the two boundaries in an orthogonal fashion to the shell variable) is determined by evaluating the gradient of the shell variable along the shell segment under the Cauchy-Riemann relations. The conformal mapping method is computationally by far inexpensive, and retains the exactness character of the steady-state magnetosheath solution. The method has a wide range of applications such as validating the numerical simulations, planning the space (planetary and heliospheric) missions, and even estimating the solar wind condition from the magnetosheath data.

How to cite: Narita, Y., Schmid, D., and Holzkamp, H.: Conformal mapping for the magnetosheath modeling problems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2835, https://doi.org/10.5194/egusphere-egu24-2835, 2024.

EGU24-3490 | Posters on site | ST2.1

Multi-case study of particle distribution functions associated with ion cyclotron waves at ballooning-interchange heads 

Evgeny V. Panov, Wolfgang Baumjohann, Martin Hosner, Rumi Nakamura, and Victor A. Sergeev

Recent THEMIS and MMS spacecraft observations confirmed the kinetic simulations showing that the kinetic Ballooning/Interchange Instability (BICI) may lead to off-equator electromagnetic ion-cyclotron waves.  The ion-cyclotron waves appeared to ripple the growing ballooning-interchange heads and to erode and thin the magnetotail current sheet at ion scales. As this wave activity may be important for initiating magnetic reconnection in the magnetotail, we aim at collecting a number of high-resolution MMS ion observations with clear signatures of the electromagnetic ion-cyclotron waves, and at investigating the particle behavior caused by the waves. Particularly, we analyze the properties of the electromagnetic ion cyclotron waves and search for signatures of wave interaction with resonant particles using partial ion distribution functions and their moments.

How to cite: Panov, E. V., Baumjohann, W., Hosner, M., Nakamura, R., and Sergeev, V. A.: Multi-case study of particle distribution functions associated with ion cyclotron waves at ballooning-interchange heads, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3490, https://doi.org/10.5194/egusphere-egu24-3490, 2024.

EGU24-4304 | Orals | ST2.1 | Highlight

Predictability of Magnetopause Location 

Zdenek Nemecek and Jana Safrankova

Understanding the dynamics and predictability of magnetopause location is crucial for space weather forecasting and the safeguarding of critical technological infrastructure. The first part of the talk surveys previous effort in development of magnetopause models that gradually involve more and more driving parameters, starting from solar wind dynamic pressure, interplanetary magnetic field (IMF) magnitude and orientation, tilt angle of the Earth dipole and/or IMF cone angle. We show that, in spite of different forms of the magnetopause surface and different functions used for quantification of effects of driving parameters, their ability of prediction of magnetopause location is nearly identical in a statistical sense. Following this survey, we discuss main contributors to the uncertainty of this prediction like variations of upstream parameters or effects of other parameters not included in the present models and suggest a possible way for development of a new, more precise, model. The last part of the talk discusses effects of foreshock and magnetosheath transients that are unpredictable but that can result in extreme magnetopause displacements.

How to cite: Nemecek, Z. and Safrankova, J.: Predictability of Magnetopause Location, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4304, https://doi.org/10.5194/egusphere-egu24-4304, 2024.

EGU24-4316 | Orals | ST2.1 | Highlight

Exploring Magnetospheric Substorm Avalanche Dynamics: on Crackling Noise Nature  

Giuseppe Consolini and Paola De Michelis

The dynamics of the Earth's magnetosphere/ionosphere system is remarkably complex, particularly in response to changes of the solar wind and interplanetary conditions. This interplay between the Earth's magnetic field and the solar wind generates a highly complex dynamics. The interaction between the interplanetary medium and the Earth's magnetosphere triggers significant changes within the magnetosphere/ionosphere system. These alterations can lead to various phenomena, including magnetospheric substorms, which exhibit an avalanche dynamics and scale-free energy dissipation. This complex behavior resembles crackling noise phenomena observed in certain physical systems. By examining the scaling properties of auroral electrojet AL-index bursts during these substorms, we have identified similarities with crackling noise in front propagation models. Furthermore, our investigation has unveiled a scaling function describing the avalanche profile of the AL-index, shedding light on the underlying mechanisms governing these bursty dynamics. These findings significantly contribute to our understanding of magnetospheric plasma sheet dynamics and the mechanisms behind the magnetospheric substorms. By linking the scale-free characteristics of these bursts to crackling noise behavior, we gain valuable insights into the underlying physics governing these complex phenomena within Earth's magnetosphere/ionosphere system.

How to cite: Consolini, G. and De Michelis, P.: Exploring Magnetospheric Substorm Avalanche Dynamics: on Crackling Noise Nature , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4316, https://doi.org/10.5194/egusphere-egu24-4316, 2024.

EGU24-4337 | ECS | Orals | ST2.1 | Highlight

A time-dependent three-dimensional magnetopause model based on quasi-elastodynamic theory 

Yaxin Gu, Yi Wang, Fengsi Wei, Xueshang Feng, Andrey Samsonov, Xiaojian Song, Yalan Chen, Boyi Wang, Pingbing Zuo, and Chaowei Jiang

The interaction between the solar wind and the Earth’s magnetosphere is one of the most important research topics in space weather and space plasma physics. The finding of the exact magnetopause position significantly enhances our knowledge of magnetospheric response to solar wind variations. While numerous magnetopause models have been constructed in the past decades, a substantial portion of them remains time-independent models, posing limitations in elucidating the dynamic movement of the magnetopause under varying solar wind conditions. This study pioneers the establishment of a time-dependent three-dimensional magnetopause model grounded in the quasi-elastodynamic pressure theory, named the POS (Position, Overall oscillation and Surface wave like-structure) model. In contrast to the existing time-dependent magnetopause models (except for numerical simulations), the POS model transcends the one-dimensional framework, providing a real-time depiction of magnetopause position and shape alterations. The model's validity is substantiated through comparisons with satellite observation. Based on an extensive dataset of satellite magnetopause crossings (exceeding 40,000 magnetopause crossing events), the POS model exhibits superior predictive accuracy (as evaluated by root-mean-square error) compared to six widely employed magnetopause models. Remarkably, the POS model demonstrates heightened efficacy under highly disturbed solar wind conditions as well as in high-latitude and flank region of magnetopause and it possesses characteristics as predictive accuracy, concise formulation, and fast computational speed. The introduction of a time-dependent three-dimensional dynamic magnetopause model not only advances our comprehension of the physical processes in space plasma and enhances our predictive capabilities for space weather on the Earth but also provides valuable insights into the dynamic processes in the magnetospheres of other planets. 

How to cite: Gu, Y., Wang, Y., Wei, F., Feng, X., Samsonov, A., Song, X., Chen, Y., Wang, B., Zuo, P., and Jiang, C.: A time-dependent three-dimensional magnetopause model based on quasi-elastodynamic theory, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4337, https://doi.org/10.5194/egusphere-egu24-4337, 2024.

EGU24-4775 | Orals | ST2.1 | Highlight

First results from the radiation belt monitors onboard the 6U CubeSat X-Ray Observatory NinjaSat 

Yo Kato and the NinjaSat Team

NinjaSat, a 6U CubeSat-sized (30 cm x 20 cm x 10 cm) X-ray observation satellite, was launched into a low Earth orbit at an altitude of 550 km in November 2023. NinjaSat is equipped with two 1U CubeSat-sized (10 cm x 10 cm x 10 cm) gas X-ray detectors (GMC) as primary detectors for astronomical observations of bright X-ray sources such as neutron stars and black holes. Initial operations of NinjaSat have been underway since January 2024.

NinjaSat is also equipped with two radiation belt monitors (RBM) as sub-detectors to protect the GMCs from discharges in the gas cells potentially caused by excessive amount of incident charged particles. NinjaSat RBM uses a 9 mm x 9 mm Si-PIN photodiode to detect any increase in the count rate of either protons or electrons by exploiting the difference in the sensor's response to protons and electrons, and sends alert signals to GMCs which help ramping down high voltage applied to gas cells in the region of high charged particle rates. NinjaSat RBM is approximately 6% of the size of a 1U CubeSat in volume and weighs only 70 grams. Because NinjaSat RBM uses inexpensive, commercially available sensors and operates on an internal board independent of the primary detectors, it can be installed on other small satellites which need to monitor surrounding charged particle environment with relatively few development resources.

Since NinjaSat will operate in a sun-synchronous orbit, a global map of charged particles can be obtained. We will present the development of NinjaSat RBM and the first results of charged particle maps in the radiation belt obtained during the initial operational period of NinjaSat.

How to cite: Kato, Y. and the NinjaSat Team: First results from the radiation belt monitors onboard the 6U CubeSat X-Ray Observatory NinjaSat, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4775, https://doi.org/10.5194/egusphere-egu24-4775, 2024.

EGU24-4965 | Posters on site | ST2.1

The wedge-like ion spectral structures in the inner magnetosphere 

Jie Ren, Qiugang Zong, Xuzhi Zhou, and Chao Yue

Energetic ions from the plasma sheet will be freshly injected into the inner magnetosphere during geomagnetic activities, and exhibit some spectral features named after the shapes of energy bands in the energy-time spectrograms such as the “nose-like” structure,“trunk-like” structure, and ion spectral gap. Using the ion observations from Van Allen Probes launched in 2012, my work revealed the existence of a new ion structures, which is the wedge-like structure of O+, He+, and H+ ions in the inner magnetosphere. The wedge-like structures have the energy range of eV-keV and can penetrate into deep regions (even L<2). Via the conjugate observations of different spacecraft and simulations, we found that the wedge-like and nose-like spectral signatures are merely the manifestations of one single structure along different spacecraft trajectories, which are associated with the intermittent substorm injections in the nightside magnetosphere. The comparisons between observations and simulations of the wedge-like structures can help find out the shortcomings of the empirical convection electric models and improve them.

How to cite: Ren, J., Zong, Q., Zhou, X., and Yue, C.: The wedge-like ion spectral structures in the inner magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4965, https://doi.org/10.5194/egusphere-egu24-4965, 2024.

EGU24-5073 | ECS | Orals | ST2.1

On the Prevalence of Lower-Hybrid Wave-Induced Electron-Scale Current Sheets related to Kelvin-Helmholtz Vortices during Southward IMF 

Kevin Alexander Blasl, Adriana Settino, Rumi Nakamura, Takuma Nakamura, Hiroshi Hasegawa, Zoltan Vörös, Martin Hosner, Evgeny Panov, Daniel Schmid, Martin Volwerk, Owen Wyn Roberts, and Yi-Hsin Liu

Numerous spacecraft missions, theories and numerical modelling have studied the Kelvin-Helmholtz instability (KHI) excited at the Earth’s magnetopause at different scales. Important insights into particle transport and mixing as well as energy conversion related to the KHI were obtained from these studies and linked to processes such as magnetic reconnection and plasma turbulence.

Recently, Blasl et al. (2022, 2023) and Nakamura et al. (2022 a, b) reported the first observations of the KHI during southward Interplanetary Magnetic Field (IMF) conditions from the Magnetospheric Multiscale (MMS) mission together with fully-kinetic Particle-In-Cell simulations designed for this event. The unprecedented resolution of the MMS mission together with large-scale kinetic simulation runs enabled a multi-scale study of the KHI. Their results showed the onset and evolution of secondary instabilities such as the Rayleigh-Taylor Instability responsible for globally deforming the vortex structures as well as the Lower-Hybrid Drift Instability (LHDI) leading to plasma mixing along the spine region of the vortices. Additionally, at 1 out of the 11 KH wave crossings they reported the observation of an electron-scale reconnecting current sheet at the interface between this mixing region and the magnetospheric plasma, as suggested by simulation results.

In this study, we revisit this previously reported MMS KH event during southward IMF and study the remaining 10 vortex structures in detail. Especially, we will characterize the signatures of LHDI-induced plasma mixing from both simulations and observations at different evolutionary stages and discuss the prevalence and signatures of small-scale current sheets at these vortex structures. First results suggest the coexistence of vortex structures at different evolutionary stages in this KH event, which will be discussed in detail. A short discussion on the influence of the IMF on this mechanism will be given at the end of the presentation.

How to cite: Blasl, K. A., Settino, A., Nakamura, R., Nakamura, T., Hasegawa, H., Vörös, Z., Hosner, M., Panov, E., Schmid, D., Volwerk, M., Roberts, O. W., and Liu, Y.-H.: On the Prevalence of Lower-Hybrid Wave-Induced Electron-Scale Current Sheets related to Kelvin-Helmholtz Vortices during Southward IMF, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5073, https://doi.org/10.5194/egusphere-egu24-5073, 2024.

Using MMS observation, we do a series of studies to investigate Hall effect in multiple reconnection cases at dayside magnetopause. The studies show the following interesting results. First, the hexapolar Hall magnetic field was observed in collisionless magnetic reconnection for the first time. And the associated electric field and electron dynamic display the different features from previous study. Second, it was found that the middle polar of hexapolar Hall magnetic field can play the role of guide field. Thus, hexapolar Hall magnetic field can make antiparallel reconnection to bear the features of guide field reconnection. Furthermore, the coexistence of hexapolar Hall magnetic field and magnetic flux rope provides the first evidence that the Hall effect in quasi-antiparallel magnetic reconnection can generate the core field inside a magnetic flux rope. Finally, for three reconnection events at the magnetopause, the quadrupolar Hall magnetic fields in them display their respective properties on the intensity asymmetry and the distributing location. The analyses indicate that the different density asymmetry inside the Hall region, but not the asymptotic density asymmetry, is an exact indicator that explains the different observed Hall patterns. This series of studies offer a new insight into the role of Hall effect in collisionless magnetic reconnection, and how the Hall effect works with the evolution of asymmetry during reconnection. 

How to cite: Zhang, Y.: Observational investigation of Hall effect in asymmetric magnetic reconnection , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5222, https://doi.org/10.5194/egusphere-egu24-5222, 2024.

EGU24-5292 | ECS | Posters on site | ST2.1

A Statistical Study of the Properties of and Geomagnetic Responses to Large, Rapid Southward Turnings of the Interplanetary Magnetic Field 

Chiara Lazzeri, Colin Forsyth, Andrei Samsonov, Graziella Branduardi-Raymont, and Yulia Bogdanova

The interplanetary magnetic field (IMF) north-south component, Bz, plays a crucial role in the interaction between the solar wind and the Earth's magnetosphere. We analyse 98 intervals in which Bz changed from > 3 nT to < -3 nT in 5 min and for which these rapid southward turnings (STs) were surrounded by consistently northward or southward IMF.
This analysis is performed separately for events in proximity of interplanetary coronal mass ejections (ICMEs) and corotating interaction regions (CIRs). We find that IMF magnitude, solar wind dynamic pressure and proton density (but also flow speed and plasma pressure in ICME-associated events) are enhanced above their median values. We analyse the maximum responses of the SML, SMU, SYM-H and PC magnetospheric indices and their timescales, but also the occurrence of geomagnetic phenomena. We find that magnetic storms followed 46.94% of events, with the strongest storms (with median SYM-H -120 nT) following ICME turnings. STs were followed by either substorms (60.20%) or enhanced convection (37.76%). While SML has similar average minima (~ -460 nT) and timescales (~ 56 min) for substorm and convection events, SMU has noticeable differences. PCN is found to have peaks (3.8 mV/m) around 30 minutes after the turning, and larger ones (4.9 mV/m) later. Stronger solar wind driving and magnetospheric responses are observed in ICME turnings. 
Examining the correlation between the geomagnetic and solar wind parameters around STs, reveals a more direct link between solar wind driving and geomagnetic response for STs than at other times.

How to cite: Lazzeri, C., Forsyth, C., Samsonov, A., Branduardi-Raymont, G., and Bogdanova, Y.: A Statistical Study of the Properties of and Geomagnetic Responses to Large, Rapid Southward Turnings of the Interplanetary Magnetic Field, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5292, https://doi.org/10.5194/egusphere-egu24-5292, 2024.

EGU24-5892 | Posters on site | ST2.1

A Statistical and Multiscale study of Kelvin-Helmholtz events under different IMF orientations  

Adriana Settino, Rumi Nakamura, Yuri Khotyaintsev, Daniel B. Graham, Kevin-Alexander Blasl, Takuma Nakamura, and Denise Perrone

The Kelvin-Helmholtz instability (KHI) is a shear-driven phenomenon frequently observed at the Earth's low-latitude magnetopause when the velocity shear is super Alfvénic. KHI represents a way for plasmas to give rise to a turbulent scenario and to convert the energy due to the large-scale motion of the shear flow into heat. Indeed, the evolution of the KHI is characterized by the nonlinear coupling of different modes, which tends to generate smaller and smaller vortices along the shear layer. Both kinetic simulations and in situ measurements, focusing on the kinetic effects during the nonlinear phase of the instability, have shown the generation of strong current sheets between well-developed vortices, and temperature anisotropy and agyrotropy at both ion and electron scales, in accordance with the multi-scale nature of the phenomenon.

Moreover, KHI is thought to play a crucial role in the transport of solar wind plasma into the magnetosphere and to efficiently contribute to the formation of the low latitude boundary layer. Although the instability threshold is equally satisfied during both northward and southward interplanetary magnetic field (IMF) conditions, in-situ measurements show that KHI privileges the northward orientation. We investigate this different behavior by analyzing the kinetic features at both boundaries and inside the KH structures. Thus, we statistically investigate several KHI crossings observed by the Magnetospheric Multiscale mission for different IMF orientations. Our statistical study can provide a better understanding about the global dynamics of the near Earth's environment and gives an important contribution to the solar wind-magnetosphere coupling mechanism.

How to cite: Settino, A., Nakamura, R., Khotyaintsev, Y., Graham, D. B., Blasl, K.-A., Nakamura, T., and Perrone, D.: A Statistical and Multiscale study of Kelvin-Helmholtz events under different IMF orientations , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5892, https://doi.org/10.5194/egusphere-egu24-5892, 2024.

EGU24-6237 | Posters on site | ST2.1 | Highlight

SMILE: a new view on the dynamic magnetosphere 

C.-Philippe Escoubet and the The SMILE team

How the solar wind and the Earth's magnetosphere interact, involving kinetic, fluid and global scales processes, is one of the key questions in space plasma physics. In situ instruments on a fleet of solar wind and magnetospheric constellation missions now provide the most detailed observations of Sun-Earth connections over multiple scales, from the smallest of a few kilometres up to the largest of a few 10s of Earth radii. However, we are still unable to fully quantify the global effects of the drivers of such connections, including the conditions that prevail throughout geospace due to the limitations of point measurements. This information is the key missing link for developing a complete understanding of how the Sun gives rise to and controls Earth's plasma environment and space weather. This is where SMILE (Solar wind Magnetosphere Ionosphere Link Explorer) comes in.

SMILE is a novel self-standing mission dedicated to observing the solar wind - magnetosphere coupling via simultaneous in situ solar ion and magnetic field measurements, soft X-ray imaging of the magnetosheath, magnetopause and polar cusps, and UV imaging of the northern hemisphere auroral oval. Remote sensing of the magnetosheath and cusps with soft X-ray imaging is made possible thanks to solar wind charge exchange (SWCX) X-ray emissions known to occur in the vicinity of the Earth's magnetosphere. SMILE is a joint mission between ESA and the Chinese Academy of Sciences (CAS) due for launch in the middle of 2025. SMILE science objectives as well as the latest scientific and technical developments, jointly undertaken by ESA, CAS and the international instrument teams, will be presented. SMILE will be complemented by ground-based observatories, in particular the newly funded Canada Space Agency SMILE Imaging Science project, as well as by theory and simulation investigations. This presentation will be dedicated to Graziella Branduardi-Raymont, SMILE mission Co-proposer and mission Co-PI, who passed away on 3rd November 2023.

How to cite: Escoubet, C.-P. and the The SMILE team: SMILE: a new view on the dynamic magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6237, https://doi.org/10.5194/egusphere-egu24-6237, 2024.

EGU24-6258 | ECS | Posters on site | ST2.1

Statistical Survey of Ion Cyclotron Wave Signatures around Earth’s Magnetotail Dipolarizations 

Martin Hosner, Rumi Nakamura, Evgeny Panov, and Daniel Schmid

In the Earth’s Magnetotail fast earthward plasma flows (so-called Bursty Bulk Flows) with a duration of several minutes and velocities of several hundreds of km/s are regularly observed in in-situ measurements. These flows are frequently accompanied by embedded co-moving, and more dipolar-shaped, magnetic flux bundles. The leading edge of such flux bundles is called a Dipolarization Front (DF). Such Earthward moving flux bundles and DFs can be formed by magnetic reconnection in the Magnetotail, as well as by the Ballooning/Interchange Instability (BICI). For the latter mechanism, simulations of the BICI suggest that, away from the central plasma sheet, the BICI heads are accompanied by electromagnetic ion cyclotron waves, and such wave signatures were indeed observed by the MMS and THEMIS spacecraft between the neutral sheet and the magnetospheric lobes.

In the present study we use years of data from NASA’s Magnetospheric Multiscale Mission (MMS) to compile a database of several hundred events. We analyze this database with the goal of a statistical description of such flux bundles with respect to ion cyclotron wave occurrence, and compare them to several parameters, such as magnetic field and plasma conditions, to further enhance the understanding of the large-scale context and origin of magnetotail dipolarizations.

How to cite: Hosner, M., Nakamura, R., Panov, E., and Schmid, D.: Statistical Survey of Ion Cyclotron Wave Signatures around Earth’s Magnetotail Dipolarizations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6258, https://doi.org/10.5194/egusphere-egu24-6258, 2024.

EGU24-6504 | Orals | ST2.1 | Highlight

Cross-Scale Processes of Magnetic Reconnection 

Kyoung-joo Hwang, Rumi Nakamura, Jonathan Eastwood, Stephen Fuselier, Hiroshi Hasegawa, Takuma Nakamura, Benoit Lavraud, Kyunghwan Dokgo, Drew Turner, Robert Ergun, and Patricia Reiff

Various physical processes in association with magnetic reconnection occur over multiple scales from the microscopic to macroscopic scale lengths. This presentation reviews multi-scale and cross-scale aspects of magnetic reconnection revealed in the near-Earth space beyond the general global-scale features and magnetospheric circulation organized by the Dungey Cycle. Significant and novel advancements recently reported, in particular, since the launch of the Magnetospheric Multi-scale mission (MMS), are highlighted being categorized into different locations with different magnetic topologies. These potentially paradigm-shifting findings include shock and foreshock transient driven reconnection, magnetosheath turbulent reconnection, flow shear driven reconnection, multiple X-line structures generated in the dayside/flankside/nightside magnetospheric current sheets, development and evolution of reconnection-driven structures such as flux transfer events, flux ropes, and dipolarization fronts, and their interactions with ambient plasmas. We emphasize key aspects of kinetic processes leading to multi-scale structures and bringing large-scale impacts of magnetic reconnection as discovered in the geospace environment. These key features can be relevant and applicable to understanding other heliospheric and astrophysical systems.

How to cite: Hwang, K., Nakamura, R., Eastwood, J., Fuselier, S., Hasegawa, H., Nakamura, T., Lavraud, B., Dokgo, K., Turner, D., Ergun, R., and Reiff, P.: Cross-Scale Processes of Magnetic Reconnection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6504, https://doi.org/10.5194/egusphere-egu24-6504, 2024.

EGU24-8122 | ECS | Posters on site | ST2.1

Capabilities of the wave telescope for multi-scale spacecraft configurations using a Vlasiator simulation 

Leonard Schulz, Ferdinand Plaschke, Karl-Heinz Glassmeier, Uwe Motschmann, Yasuhito Narita, Minna Palmroth, Owen Roberts, and Lucile Turc

We present an analysis of the wave properties in Earth's foreshock and dayside magnetosphere in a Vlasiator global magnetospheric simulation, using the wave telescope analysis technique. Vlasiator is a Hybrid-Vlasov plasma simulation and treats electrons as a fluid while protons are described by distribution functions. In anticipation of future multi-scale spacecraft space plasma missions such as HelioSwarm or the proposed Plasma Observatory, artificial spacecraft constellations consisting of more than 4 satellites have been used to measure the electromagnetic field and plasma properties in the Vlasiator run. Using the wave telescope analysis technique - originally developed for the 4-spacecraft Cluster mission - power spectra in k-space are estimated, enabling the determination of properties of waves and transient phenomena from those multi-scale spacecraft data. We test different spacecraft configurations probing regions mainly in the foreshock and consider conversion to the plasma rest frame, dispersion analysis as well as spectrum filtering to account for the spatial Nyquist limit in k-space spectra.

How to cite: Schulz, L., Plaschke, F., Glassmeier, K.-H., Motschmann, U., Narita, Y., Palmroth, M., Roberts, O., and Turc, L.: Capabilities of the wave telescope for multi-scale spacecraft configurations using a Vlasiator simulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8122, https://doi.org/10.5194/egusphere-egu24-8122, 2024.

EGU24-8171 | Posters on site | ST2.1

Foreshock fluctuation and its behaviors 

Gilbert Pi, Zdenek Nemecek, and Jana Safrankova

The foreshock region is a turbulent area that forms before a quasi-parallel shock. It is caused by the interaction between reflected particles from the bow shock and oncoming waves in the solar wind. Typically, the foreshock is located on the dawn side. However, when the interplanetary magnetic field (IMF) points in a radial or anti-radial direction, the foreshock region will move to the nose of the bow shock, covering almost the entire dayside magnetospheric system. This change triggers various phenomena in the magnetospheric system, such as magnetopause expansion and the generation of foreshock transients like sHFA. Our previous studies have shown that foreshocks behave differently depending on different upstream cone angles. The fluctuation is enhanced when approaching the bow shock with an IMF near the Parker spiral structure, but for radial IMF, it remains almost constant. In this study, we investigate the frequency, polarization, and amplitude of fluctuations for different cone angles to uncover the underlying mechanisms.

How to cite: Pi, G., Nemecek, Z., and Safrankova, J.: Foreshock fluctuation and its behaviors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8171, https://doi.org/10.5194/egusphere-egu24-8171, 2024.

Magnetic reconnectio­n, a fundamental plasma process transforming magnetic field energy into particle energy, is ubiquitous in space and responsible for many explosive phenomena, such as solar flares and gamma ray bursts. Recent numerical theories have predicted that reconnection fronts far from the primary reconnection region can host secondary reconnection in three-dimensional scenarios, different from the conventional two-dimensional diagram where only one X-line stands to sustain reconnection. In this study, we provide direct observational evidence for ongoing secondary reconnection in the reconnection front, via using the unprecedently high-cadence data from NASA’s MMS mission. The secondary reconnection is identified by the presence of X-line, super-Alfvénic electron jet, and non-ideal energy dissipation. Different from the primary ion-electron reconnection, the secondary reconnection is electron-only, with its X-line quasi-perpendicular to the primary X-line. Hence reconnection, when evolving from local to global scales, becomes essentially three-dimensional with different patterns developed. These results provide crucial insights into understanding cross-scale energy transport driven by reconnection in space plasmas.

How to cite: Chengming, L.: Observations of Electron Secondary Reconnection in Magnetic Reconnection Front, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8525, https://doi.org/10.5194/egusphere-egu24-8525, 2024.

EGU24-8592 | Posters on site | ST2.1

Anomalous flows in the magnetosheath and their relation to the magnetopause motion 

Kostiantyn Grygorov, Oleksandr Goncharov, Jana Šafránková, Zdeněk Němeček, and Jiří Šimůnek

The magnetopause (MP) is a critical boundary dividing the space controlled by the Earth's magnetic field from the solar wind and interplanetary magnetic field (IMF). Its position is mainly influenced by the solar wind dynamic pressure and the north-south IMF component (Bz), which are included in various empirical MP models. However, different transient phenomena, such as hot flow anomalies (HFAs) and magnetosheath jets/plasmoids, generated at the bow shock, can significantly impact the MP, redirecting the plasma flow sunward and triggering a rapid displacement of the local MP in this direction.

We present our preliminary results of case and statistical studies of such transient events, aiming to estimate the contribution of their effect on velocity of MP motion. We also discuss the influence of these structures on the local MP shape and orientation. The statistics reveals favorable upstream solar wind conditions and accompanying local magnetosheath parameters.

How to cite: Grygorov, K., Goncharov, O., Šafránková, J., Němeček, Z., and Šimůnek, J.: Anomalous flows in the magnetosheath and their relation to the magnetopause motion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8592, https://doi.org/10.5194/egusphere-egu24-8592, 2024.

EGU24-8704 | Posters on site | ST2.1

Connection of the magnetosheath jet-like structures with the foreshock and impact on the magnetopause 

Oleksandr Goncharov, Niki Xirogiannopoulou, Kostiantyn Grygorov, Jana Safrankova, and Zdenek Nemecek

Plasma structures with enhanced dynamic pressure, density or speed are often observed in Earth’s magnetosheath. These structures, known as jets and fast plasmoids, can be registered in the magnetosheath, downstream of both the quasi-perpendicular and quasi-parallel bow shocks Using measurements by the Magnetospheric Multiscale (MMS) spacecraft, Goncharov et al., (2020) showed similarities in the plasma properties of the jets and fast plasmoids. On the other hand, they pointed out that the different magnetic fields inside the structures suggest that the formation mechanisms are not the same. Hybrid simulations by Preisser et al., (2020) have shown differences in the mechanisms of jet and embedded plasmoid formation. Previous studies established that foreshock structures can be a source of the jets (Raptis et al., 2022). Xirogiannopoulou et al. (2023) found that the subsolar foreshock contains several types of structures with enhanced density or/and magnetic field magnitude, like plasmoids, SLAMS and mixed structures. Following the results of Xirogiannopoulou et al. (2023) and Goncharov et al., (2020), we compare our MMS measurements with THEMIS observations. Based on our comparative analysis, we discuss features of jet-like structures, their properties, occurrence, evolution, relation to the foreshock, and impact on the magnetopause.

How to cite: Goncharov, O., Xirogiannopoulou, N., Grygorov, K., Safrankova, J., and Nemecek, Z.: Connection of the magnetosheath jet-like structures with the foreshock and impact on the magnetopause, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8704, https://doi.org/10.5194/egusphere-egu24-8704, 2024.

EGU24-8777 | ECS | Posters on site | ST2.1

A New Method of Estimating the Magnetopause Speed of Motion 

Mrittika Ghosh, Jana Šafránková, and Zdeněk Němeček

The magnetopause is the boundary where the solar wind and magnetosphere pressures balance each other. Once the upstream solar wind conditions change, the magnetopause moves to a new position and changes its shape accordingly. Previous studies usually calculate the speed of magnetopause motion from parameters of two crossings that were close in location and time. However, such events are relatively rare. A new hypothesis suggests application of the ion speed in the magnetopause layers to estimate the speed of magnetopause motion. As a boundary that plasma cannot pass through, the ion speed in the magnetopause should be related to the magnetopause speed. Our study aims to check whether this hypothesis is correct or not by using numerous magnetopause crossings recorded by the THEMIS mission. The magnetopause speed will be first calculated using the traditional method and compared with the results estimated using the new method.

How to cite: Ghosh, M., Šafránková, J., and Němeček, Z.: A New Method of Estimating the Magnetopause Speed of Motion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8777, https://doi.org/10.5194/egusphere-egu24-8777, 2024.

EGU24-8779 | ECS | Posters on site | ST2.1

Comparing L1 to near-Earth data for magnetosheath jet studies 

Georg Blüthner, Manuela Temmer, and Florian Koller

This study explores large-scale solar wind structures and differences in observations between measurement points at L1 and near Earth. Specifically, we focus on coronal mass ejections (CMEs) and stream interaction regions (SIR) together with their distinct substructures. Our study is based on existing CME/SIR lists of events defined by Koller et al. [2022] in OMNI data. For the given time ranges, we compare timing and appearance for the structures in the solar wind plasma and magnetic field parameters as probed by ACE/Wind, OMNI, and THEMIS. Our approach involves creating a database of identified structures, especially those observed by multiple spacecraft, facilitating statistical analysis. Matrix profiles will be employed to unveil recurring patterns and relationships among the substructures measured at different locations. This research will contribute to a more comprehensive understanding of solar wind dynamics and magnetospheric responses to the specific structures which is especially important for magnetosheath jets which are short-lived pressure enhancements.

How to cite: Blüthner, G., Temmer, M., and Koller, F.: Comparing L1 to near-Earth data for magnetosheath jet studies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8779, https://doi.org/10.5194/egusphere-egu24-8779, 2024.

EGU24-9641 | ECS | Posters on site | ST2.1

Energy conversion in a compressed magnetospheric separatrix: Observations and simulations 

Mohammed Baraka, Olivier Le Contel, Patrick Canu, Soboh Alqeeq, Mojtaba Akhavan-Tafti, Alessandro Retino, Thomas Chust, Sergio Toledo-Redondo, Jeremy Dargent, Arnaud Beck, Giulia Cozzani, and Cecilia Norgren and the MMS Team

Magnetic reconnection is a fundamental process that is ubiquitous in the universe. It converts magnetic field energy into heating and acceleration of plasma. On the dayside of the Earth’s magnetosphere, it is responsible for the dominant transport of plasma, momentum, and energy across the magnetopause from the solar wind into the Earth’s magnetosphere. The present study reports on a magnetic reconnection event with a guide field (BM=0.5 B) detected by the Magnetospheric Multiscale mission (MMS) on October 21, 2015, around 04:39:24 UT. The MMS traversed the compressed magnetospheric separatrix and the reconnection jet far from the diffusion regions and in specific conditions: observing magnetospheric cold ions and a large magnetosheath density of up to 150 p/cc. We investigate the generalized Ohm’s law and the energy conversion process in the spacecraft frame (J.E) and in the fluid frame (J.E`) associated with the separatrix crossing under such conditions. We further validate and compare our results using 2D fully kinetic simulation.

How to cite: Baraka, M., Le Contel, O., Canu, P., Alqeeq, S., Akhavan-Tafti, M., Retino, A., Chust, T., Toledo-Redondo, S., Dargent, J., Beck, A., Cozzani, G., and Norgren, C. and the MMS Team: Energy conversion in a compressed magnetospheric separatrix: Observations and simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9641, https://doi.org/10.5194/egusphere-egu24-9641, 2024.

EGU24-9845 | Posters on site | ST2.1

On the influence of solar wind turbulence on the Earth's foreshock dynamics 

Francesco Pucci, Etienne Behar, Pierre Henri, Cyril Simon Wedlund, Luis Preisser, Giulio Ballerini, and Francesco Califano

We present the results of two numerical simulations of the interaction between the solar wind and a planetary Earth-like magnetosphere. We use the hybrid particle-in-cell (PIC) code Menura, which allows for injecting a turbulent solar wind [1]. The two numerical simulations we present only differ one from the other on the nature of the solar wind, which is laminar in one case and turbulent in the other. Even though we poorly resolve ion scales because of computational constraints, we observe the development of a foreshock in the quasi-parallel shock region formed by kinetic effects due to the presence of reflected particles. 

We focus our analysis on the spatial properties of the reflected ion beams and compare them in the case of laminar and turbulent solar wind. In the laminar case, we observe the presence of fast modes excited by reflected particles and find homogeneous density and temperature of the ion beam in the foreshock region. Instead, in the turbulent case,  we find that fluctuations in the foreshock are not simple fast waves but result from the interaction between solar wind turbulence and reflected particles. We also observe that density and temperature are modulated in space in contrast with the laminar case. We argue that this modulation arises from the complex shape of the magnetic field, in which field line random walk and perpendicular diffusion are enhanced with respect to the laminar case.   


[1] Behar, E., Fatemi, S., Henri, P., & Holmström, M. (2022, May). Menura: a code for simulating the interaction between a turbulent solar wind and solar system bodies. In Annales Geophysicae (Vol. 40, No. 3, pp. 281-297). Copernicus GmbH.

How to cite: Pucci, F., Behar, E., Henri, P., Wedlund, C. S., Preisser, L., Ballerini, G., and Califano, F.: On the influence of solar wind turbulence on the Earth's foreshock dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9845, https://doi.org/10.5194/egusphere-egu24-9845, 2024.

Transpolar arcs (TPAs) are extensions of auroral emission poleward beyond the main ovals, forming partial or complete bisections known as ‘theta’ auroras. A prominent hypothesis suggests that a TPA occurs through stagnation of magneto-plasma returning from Earth’s magnetotail under northward interplanetary magnetic field (IMF), resulting in a ‘wedge’ of closed magnetic field lines in the open polar cap on which particles resemble those in the nightside equatorial plasma sheet. It has been proposed that a TPA’s closed-field lines may reach sufficiently high latitude to magnetically reconnect with the IMF at the lobe magnetopause, leading to observed coincidence of the TPA and a cusp spot. Using conjugate data from Cluster, Imager for Magnetopause-to-Aurora Global Exploration (IMAGE), Special Sensor Ultraviolet Spectrographic Imager (SSUSI), and other instruments, we demonstrate at least one case study of potential first in situ detection of TPA-IMF magnetic reconnection with magneto-plasma and visual aurora evidence, and several further instances of particles on closed magnetic field lines near the lobe magnetopause. Pending affirmative analysis, the existence of TPA-IMF reconnection events will not only further support the ‘wedge’ TPA formation hypothesis, but also indicate that lobe reconnection can open topologically closed nightside magnetic field lines, introducing new polar cap dynamics under northward IMF.

How to cite: Kaweeyanun, N. and Fear, R.: In Situ Observations of Interaction Between the Closed Magnetic Field of Earth’s Transpolar Auroral Arcs and the Interplanetary Magnetic Field, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10383, https://doi.org/10.5194/egusphere-egu24-10383, 2024.

EGU24-10841 | Posters on site | ST2.1

Solar wind-driven Alfvénic energy flow in the dayside magnetosphere 

Andreas Keiling

There is ample evidence for significant Alfvénic activity in the dayside magnetosphere. One reported aspect has been the relationship between the IMF/solar wind parameters and the global Alfvénic Poynting flux in the coupled system. In this investigation, we add to the body of knowledge by presenting the dynamics of Alfvén waves as a global phenomenon as it occurs at the entry point to the dayside auroral acceleration region. In particular, we show how the global Alfven wave power and morphology evolves during geomagnetic storm developments, from storm sudden commencement to the end of storm recovery. To investigate this, we used data from the Polar satellite. By comparing our results with observations from low-altitude satellites, we demonstrate the dissipation of Alfvénic power in the dayside. During storms, the transfer of energy from the solar wind into geospace is largely increased, leading to enhanced energy transfer and deposition within the magnetosphere and ionosphere. Here, we are aiming to understand the wave aspect during storm evolution.

How to cite: Keiling, A.: Solar wind-driven Alfvénic energy flow in the dayside magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10841, https://doi.org/10.5194/egusphere-egu24-10841, 2024.

EGU24-11173 | ECS | Posters on site | ST2.1 | Highlight

Unusual shrinkage and reshaping of Earth’s magnetosphere under a strong northward interplanetary magnetic field 

Xiangyu Wang, Qinghe Zhang, Chi Wang, Yongliang Zhang, Binbin Tang, Zanyang Xing, Kjellmar Oksavik, Larry R. Lyons, Michael Lockwood, Qiugang Zong, Guojun Li, Jing Liu, Yuzhang Ma, and Yong Wang

Open magnetic flux in the polar cap almost completely disappeared and the Earth's magnetotail was compressed into a calabash shape during the 9th April 2015 coronal mass ejection, according to magnetohydrodynamic simulations and observations from DMSP and THEMIS.The Earth's magnetosphere is the region of space where plasma behavior is dominated by the geomagnetic field. It has a long tail typically extending hundreds of Earth radii (R-E) with plentiful open magnetic fluxes threading the magnetopause associated with magnetic reconnection and momentum transfer from the solar wind. The open-flux is greatly reduced when the interplanetary magnetic field points northward, but the extent of the magnetotail remains unknown. Here we report direct observations of an almost complete disappearance of the open-flux polar cap characterized by merging poleward edges of a conjugate horse-collar aurora (HCA) in both hemispheres' polar ionosphere. The conjugate HCA is generated by particle precipitation due to Kelvin-Helmholtz instability in the dawn and dusk cold dense plasma sheets (CDPS). These CDPS are consist of solar wind plasma captured by a continuous dual-lobe magnetic reconnections, which is further squeezed into the central magnetotail, resulting in a short "calabash-shaped" magnetotail.

How to cite: Wang, X., Zhang, Q., Wang, C., Zhang, Y., Tang, B., Xing, Z., Oksavik, K., Lyons, L. R., Lockwood, M., Zong, Q., Li, G., Liu, J., Ma, Y., and Wang, Y.: Unusual shrinkage and reshaping of Earth’s magnetosphere under a strong northward interplanetary magnetic field, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11173, https://doi.org/10.5194/egusphere-egu24-11173, 2024.

EGU24-11903 | Orals | ST2.1 | Highlight

The ESA M7 candidate mission Plasma Observatory. 

Maria Federica Marcucci and Alessandro Retinò and the Plasma Observatory team

Particle energization and transport of energy are key open problems of space plasma physics. Their comprehension has implications on research fields that span from space weather to the understanding of the farthest astrophysical plasmas. The Magnetospheric System is the complex and highly dynamic plasma environment where the strongest energization and energy transport occurs in near-Earth space.  Previous multi-point observations from missions such as ESA/Cluster and NASA/MMS have greatly improved our understanding of plasma processes and evidenced the fundamental role of cross-scales coupling. Simultaneous measurements at both large, fluid and small, kinetic scales are required to resolve scale coupling and ultimately fully understand plasma energization and energy transport processes. Such measurements are currently not available. Here we present the Plasma Observatory (PO) multi-scale mission concept tailored to study plasma energization and energy transport in the Earth's Magnetospheric System through simultaneous measurements at both fluid and ion scales. These are the scales at which the largest amount of electromagnetic energy is converted into energized particles and energy is transported. PO baseline mission includes one mothercraft (MSC) and six identical smallsat daughtercraft (DSC) in two nested tetrahedra formation with MSC at the common vertex for both tetrahedra. PO orbit is an HEO 8x18 RE orbit, covering all the key regions of the Magnetospheric System including the foreshock, the bow shock, the magnetosheath, the magnetopause, the magnetotail current sheet, and the transition region. Along the orbit, the separations between the spacecraft range from fluid (5000 km) to ion (30 km) scales. The MSC payload provides a complete characterization of electromagnetic fields and particles in a single point with time resolution sufficient to resolve kinetic physics at sub-ion scales (for both protons and heavy ions). The DSCs have identical payload, simpler than the MSC payload, yet giving a full characterization of the plasma at the ion and fluid scales. PO is the next logical step after Cluster and MMS and will allow us to resolve for the first time scale coupling in  the Earth's Magnetospheric System, leading to transformative advances in the field of space plasma physics. Plasma Observatory  is one of the three ESA M7 candidates, which have been selected in November 2023 for a competitive Phase A with a mission selection planned in 2026 and launch in 2037.

How to cite: Marcucci, M. F. and Retinò, A. and the Plasma Observatory team: The ESA M7 candidate mission Plasma Observatory., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11903, https://doi.org/10.5194/egusphere-egu24-11903, 2024.

EGU24-12236 | Orals | ST2.1 | Highlight

A Particle-in-Cell Simulation of Ion and Electron Dynamics from Tail Reconnection to the Inner Magnetosphere 

Raymond Walker, Mostafa El-Alaoui, Liutauras Rusaitis, Giovanni Lapenta, Nicole Echterling, and David Schriver

We have used a PIC simulation combined with a global MHD simulation to model the interaction between magnetotail plasma from reconnection and inner magnetosphere region. The PIC simulation extended from the solar wind outside of the bow shock to beyond the reconnection region in the tail. The initial simulation was carried out with nominal solar wind parameters and southward IMF. A partial ring current and diamagnetic current formed in the PIC simulation.  Initially, the partial ring current formed by drift of the particles loaded into the PIC simulation. However, the PIC run lasted ~2 m and by the end of the calculation particles from tail reconnection had reached the inner magnetosphere and contributed to the partial ring current.  The sources of the particles to the inner magnetosphere are bursty bulk flows (BBFs) that originate from a complex pattern of reconnection in the near-Earth magnetotail at about XGSM=-25- to -30 RE. After the particles jet away from the initial reconnection site, they can undergo further acceleration at secondary reconnection sites. Electrons jet away from the reconnection much faster than the ions setting up an ambipolar electric field allowing the ions to catch up after 4-14 di (ion inertial lengths). The initial energy flux in the BBFs is mainly in the form of kinetic energy flux from the jetting particles, but as they move earthward the energy flux changes to enthalpy flux. The energy flux in the simulated ring current is primarily in the form of enthalpy flux. The power delivered from the tail reconnection in the simulation to the inner magnetosphere (~6X1011 W) is consistent with observations.

 

How to cite: Walker, R., El-Alaoui, M., Rusaitis, L., Lapenta, G., Echterling, N., and Schriver, D.: A Particle-in-Cell Simulation of Ion and Electron Dynamics from Tail Reconnection to the Inner Magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12236, https://doi.org/10.5194/egusphere-egu24-12236, 2024.

EGU24-13267 | Posters on site | ST2.1 | Highlight

Analysis of Cluster data with the publicly available GRMB (Geospace Region and Magnetospheric Boundary) dataset 

Benjamin Grison, Fabien Darrouzet, Romain Maggiolo, Mykhaylo Hayosh, and Matthew Taylor

The Cluster mission consists of 4 identical spacecraft, each carrying 11 scientific experiments. The spacecraft were launched in July and August 2000 into near polar inclined, 19x4 RE elliptic orbits. All four spacecraft are still in operation 23 years later. The magnetosphere environment is highly dynamic and its regions cannot be accessed by the orbital information alone. The purpose of this study is to develop a comprehensive dataset, providing information on Geospace Region and Magnetospheric Boundaries (GRMB) crossed by each of the four Cluster spacecraft, and to deliver it to the Cluster Science Archive (CSA).

The GRMB dataset provides a classification useful for the scientific community. Therefore, the methodology does not define what is a bow shock or what is a magnetopause. The goal is to have labeled regions that contain the bow-shocks or magnetopauses. And then each user can apply its own definition on the appropriate label subset.

The GRMB list contains two kinds of items:

  • Regions: Magnetosphere, Magnetosheath, Lobe, Solar wind / Foreshock, Plasmasheet, Plasmasphere

  • Transition regions: Bow shock TR, Magnetopause TR, Polar regions, Plasmasheet TR, Plasmapause TR

Transition regions can include properties matching several regions. For example, a bow shock TR can include short periods of solar wind or magnetosheath. Solar wind and magnetosheath should not include bow shock crossings.

The GRMB dataset is based on more than 40 data products available at CSA, taken from 7 instrument suites. The methodology relies on the visual identification of the boundaries between two consecutive GRMB items.

The methodology, the criteria applied for the boundary identification, and the dataset validation are presented. The dataset is not yet fully completed but the Cluster location is already available for more than 5 years per spacecraft.

The visualization of the regions, and their physical properties, crossed by the Cluster spacecraft during several years, illustrates the scientific interest of this dataset.

How to cite: Grison, B., Darrouzet, F., Maggiolo, R., Hayosh, M., and Taylor, M.: Analysis of Cluster data with the publicly available GRMB (Geospace Region and Magnetospheric Boundary) dataset, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13267, https://doi.org/10.5194/egusphere-egu24-13267, 2024.

EGU24-13469 | Posters on site | ST2.1 | Highlight

The Special Issue on Modeling and Data Analysis Methods for the SMILE mission 

Tianran Sun, Hyunju Connor, and Andrey Samsonov

The SMILE (Solar wind Magnetosphere Ionosphere Link Explorer) mission (http://www.nssc.cas.cn/smile/) is a scientific space mission, jointly supported by the European Space Agency (ESA) and the Chinese Academy of Sciences (CAS). SMILE aims to study the solar wind-magnetosphere coupling in a novel approach: global imaging of the Earth’s magnetosheath and cusps in the soft X-ray band. At the same time, it also provides UV imaging of the northern auroral regions, completing the detection of solar wind–magnetosphere–ionosphere coupling in a global way. The time frame for launch is in 2025. This talk summarizes the recent progress of SMILE Modeling Working Group (MWG), specifically a special issue on Earth and Planetary Physics (EPP) with 23 articles to provide the international space science community with works regarding the modeling and data analysis methods developed during the pre-studies of the SMILE mission. We categorize the articles into the following topics and give some brief comments: (1) instrument descriptions of the Soft X-ray Imager (SXI), (2) modeling of the X-ray signals, (3) data processing of the images, (4) tracing the boundary locations from the simulated images, (5) physical phenomenon related to the scientific goals of SMILE-SXI, (6) modeling of the aurora, and (7) ground-based support for SMILE.

How to cite: Sun, T., Connor, H., and Samsonov, A.: The Special Issue on Modeling and Data Analysis Methods for the SMILE mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13469, https://doi.org/10.5194/egusphere-egu24-13469, 2024.

EGU24-13578 | ECS | Orals | ST2.1 | Highlight

Evaluating the magnetic and plasma flux transport in the plasma sheet during geomagnetic storms using MMS 

Savvas Raptis, Slava Merkin, Shin Ohtani, and Matina Gkioulidou

During geomagnetic storms, the nightside of Earth’s magnetosphere experiences significant disturbances, featuring various phenomena that interact with one another. These include enhanced convection and particle injections influencing ring current development, alongside mesoscale structures like bursty bulk flows (BBFs) and dipolarization fronts, which play roles in plasma and magnetic flux transport within the plasma sheet. However, their specific functions during storms are not fully comprehended.

In our work, we evaluate the transport of magnetic and plasma flux in the plasma sheet region using data obtained from NASA’s Magnetosphere Multiscale (MMS) mission. Leveraging MMS's extensive measurements from the plasma sheet, a statistical analysis is conducted based on nearly 200,000 data points (at 4.5-second resolution) obtained from the Fast Plasma Investigator (FPI) during quiet and disturbed geomagnetic periods.

The statistical examination primarily focuses on how different properties describing convection in the plasma sheet vary across distinct phases of storms (main and recovery) and at various distances from Earth. Furthermore, we compare our results with these obtained by prior research from other missions. Additionally, we assess whether variations in instrumental capabilities, such as time resolution and energy range among different instruments on MMS, could influence the statistical outcomes

How to cite: Raptis, S., Merkin, S., Ohtani, S., and Gkioulidou, M.: Evaluating the magnetic and plasma flux transport in the plasma sheet during geomagnetic storms using MMS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13578, https://doi.org/10.5194/egusphere-egu24-13578, 2024.

The low-latitude ionosphere is effectively shielded from the high latitude convection electric field during geomagnetic quiet times because region-2 field-aligned currents associated with the partial ring current act to oppose the convection electric field associated with region-1 field-aligned currents. However, the low-latitude ionosphere can be directly coupled to the enhanced magnetospheric electric field through prompt penetration of convection electric field during periods of strong solar wind-magnetosphere interaction. The mechanisms that lead to the generation of prompt penetration electric field during enhanced solar wind-magnetosphere-ionosphere coupling are complex and not fully understood. We study the evolution of field-aligned currents and the equatorial electrojet during the March and April 2023 geomagnetic storm to understand the processes involving solar wind disturbances interacting with the magnetosphere and coupling into the polar ionosphere, and how the low-latitude ionosphere responded to the enhanced magnetosphere-ionosphere coupling. We will present the observations in the solar wind-magnetosphere-ionosphere system, in particular, field-aligned currents at high latitude ionosphere by Swarm and the equatorial electrojet by Swarm and ground-based magnetometers.

 

How to cite: Le, G., Liu, G., and Yizengaw, E.: Observations of solar wind-magnetosphere-ionosphere coupling and its impact on equatorial ionospheric electrodynamics during the March and April 2023 geomagnetic storms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13633, https://doi.org/10.5194/egusphere-egu24-13633, 2024.

EGU24-13795 | ECS | Orals | ST2.1

Mid-latitude Electric Field Response during Isolated Substorms: Effects of SCW Location and Shielding 

Moe Hayashi, Akimasa Yoshikawa, and Akiko Fujimoto

The substorm current wedge (SCW) characterizes the current system during substorms. The high-latitude electric field associated with the SCW penetrates toward mid- and low-latitudes. Various case studies have reported that the penetration electric field becomes stronger with the region-1 (R1) sense SCW, while the region-2 (R2) sense SCW shields the electric field. However, the statistical properties of the penetration electric field remain unclear. Moreover, the detailed relationship between the SCW's location and the electric field has been seldom examined. In this study, using substorms that occurred from 2010 to 2013, we evaluated the effects of shielding and statistically investigated its impact on the mid-latitude electric field using the following methods. We determined the temporal development of the SCW structure from the north-south and east-west components of the ground magnetic field and evaluated the effect of shielding, based on the magnitude of the R1/R2 SCW by AMPARE. We then analyzed the relation between these and the direction and magnitude of the electric field from Kyushu University’s FM-CW radar at midlatitude. The results show that, when the R1 SCW is more dominant, a westward electric field is observed in the center of the SCW and an eastward electric field is observed on the outside. The magnitude of those electric fields depends on the scale of the substorms. When the R2 SCW is comparable to the R1 SCW, these electric fields are shielded or overshielded, resulting in a smaller magnitude or opposite direction of the electric field. These findings suggest that the strength of the R2 SCW and the location of the SCW are the major contributors to the penetrating electric field.

How to cite: Hayashi, M., Yoshikawa, A., and Fujimoto, A.: Mid-latitude Electric Field Response during Isolated Substorms: Effects of SCW Location and Shielding, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13795, https://doi.org/10.5194/egusphere-egu24-13795, 2024.

EGU24-13917 | ECS | Posters on site | ST2.1

Hall Nature Ahead of Dipolarization Fronts in the Earth's Magnetotail 

Lei Wang and Can Huang

Dipolarization front (DF), a common magnetic structure at the leading edge of fast plasma jets in the Earth's magnetotail, plays an important role in magnetic energy release and may even modify the magnetotail energy budgets. To date, the physical process within the structure has been well studied. However, the effect of the structure on the background plasma sheet remains elusive. Using recent high-quality data from the Magnetospheric Multiscale (MMS) mission, we statistically investigate this issue. Ahead of the DF, we find a bipolar By structure, which is consistent with the local Hall current system. The main carriers of the current system are also studied. Our research advances the understanding of the interaction between the DF and ambient undisturbed plasma environment.

How to cite: Wang, L. and Huang, C.: Hall Nature Ahead of Dipolarization Fronts in the Earth's Magnetotail, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13917, https://doi.org/10.5194/egusphere-egu24-13917, 2024.

EGU24-14405 | Orals | ST2.1 | Highlight

Global-Scale Magnetosphere Convection Driven by Dayside Magnetic Reconnection 

Lei Dai, Minghui Zhu, Yong Ren, Walter Gonzalez, Chi Wang, David Sibeck, Andrey Samsonov, Philippe Escoubet, Binbin Tang, Jiaojiao Zhang, and Graziella Branduardi-Raymont

Plasma convection on a global scale is a fundamental feature of planetary magnetosphere. The Dungey cycle explains that steady-state convection within the closed part of the magnetosphere relies on magnetic reconnection in the nightside magnetospheric tail. Nevertheless, time-dependent models of the Dungey cycle suggest an alternative scenario where magnetospheric convection can be solely driven by dayside magnetic reconnection. In this study, we provide direct evidence supporting the scenario of dayside-driven magnetosphere convection. The driving process is closely connected to the evolution of Region 1 and Region 2 field-aligned currents. Our global simulations demonstrate that intensified magnetospheric convection and field-aligned currents progress from the dayside to the nightside within 10-20 minutes, following a southward turning of the interplanetary magnetic field. Observational data within this short timescale also reveal enhancements in both magnetosphere convection and the ionosphere's two-cell convection. These findings provide insights into the mechanisms driving planetary magnetosphere convection, with implications for the upcoming Solar-Wind-Magnetosphere-Ionosphere Link Explorer (SMILE) mission.

How to cite: Dai, L., Zhu, M., Ren, Y., Gonzalez, W., Wang, C., Sibeck, D., Samsonov, A., Escoubet, P., Tang, B., Zhang, J., and Branduardi-Raymont, G.: Global-Scale Magnetosphere Convection Driven by Dayside Magnetic Reconnection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14405, https://doi.org/10.5194/egusphere-egu24-14405, 2024.

EGU24-15083 | Posters on site | ST2.1

Constellation of N Spacecraft : the Aliasing Problem 

Gérard M. Chanteur

Constellations of N spacecraft allow to separate spatial and temporal variations of the electromagnetic field in space as demonstrated by achievements of CLUSTER and MMS missions. Future missions in preparation, involving more than four spacecraft, will offer new opportunities beside proper technological progress in sensors and electronic design : the genuine and promising aspect is the number of spacecraft larger than four. Four spacecraft is the minimal configuration to estimate gradients and to do spatial filtering in three dimensions. More than four spacecraft gives additional degrees of freedom by weighting the constellation ; a numerical weight is attributed to each spacecraft for computing gradients or doing spatial filtering. It has been early recognized that spatial filtering by a constellation of spacecraft is limited by spatial aliasing ; theoretical considerations, for example dispersion relations, allow to discriminate aliased energy peaks. Discriminating aliased energy peaks with more than four space spacecraft is possible just by changing the weighting of the constellation as will be shown for the simplest case N=5. First the aliasing equation is reminded, then the fundamental cell is defined and visualized, and it is shown that aliased peaks are moving when changing the weighting. Meanwhile non-aliased peaks are unaffected.

How to cite: Chanteur, G. M.: Constellation of N Spacecraft : the Aliasing Problem, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15083, https://doi.org/10.5194/egusphere-egu24-15083, 2024.

EGU24-15192 | Orals | ST2.1

Examining Interhemispheric Properties of the Cusp 

Kevin Pham, William Lotko, Ying Zou, Binzheng Zhang, Roger Varney, and Pauline Dredger

The magnetospheric cusp is a narrow region of geospace where the solar wind has direct access to the ionosphere and thermosphere. The low-altitude projection of the cusp is a site of concentrated energy dissipation, which leads to extraordinary thermospheric upwelling and prodigious outflows of ionospheric ions into the magnetosphere.  Although interhemispheric and seasonal differences in cusp morphology and properties are recognized, statistical empirical identifications and models do not properly capture important temporal and spatial features of the cusp.  We have analyzed cusp location, size and energization, and dynamics, using different identification methods applied to the Multiscale Atmosphere Geospace Environment (MAGE) global simulation model.  Interhemispheric differences are considered for a variety of seasonal and solar wind conditions.  Preliminary results indicate that under strong IMF By conditions, commonly used cusp identification methods do not agree and are associated with the direct-entry and Alfvenic cusps not being collated.  Furthermore, we find that the simulated cusp is not discernable in one hemisphere but is pronounced in the other hemisphere.  We explore under what conditions this occurs.

How to cite: Pham, K., Lotko, W., Zou, Y., Zhang, B., Varney, R., and Dredger, P.: Examining Interhemispheric Properties of the Cusp, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15192, https://doi.org/10.5194/egusphere-egu24-15192, 2024.

EGU24-16113 | ECS | Posters on site | ST2.1

Finding reconnection lines and flux rope axes via local coordinates in global ion-kinetic magnetospheric simulations 

Markku Alho, Giulia Cozzani, Ivan Zaitsev, Fasil Tesema Kebede, Urs Ganse, Markus Battarbee, Maarja Bussov, Maxime Dubart, Sanni Hoilijoki, Leo Kotipalo, Konstantinos Papadakis, Yann Pfau-Kempf, Jonas Suni, Vertti Tarvus, Abiyot Workayehu, Hongyang Zhou, and Minna Palmroth

Magnetic reconnection is a crucially important process for energy transfer in plasma physics, the substorm cycle of Earth's magnetosphere and solar flares being prime examples. While 2D models have been widely applied to study reconnection, investigating reconnection in 3D is still in many aspects an open problem. Finding sites of magnetic reconnection in a 3D setting is not a trivial task, with several approaches from topological skeletons to Lorentz transformations proposed to tackle the issue. This work presents a complementary method by noting that the magnetic field structures near reconnection lines exhibit two-dimensional features that can be identified in a suitably chosen local coordinate system. We present applications of this method, with two approaches, to a hybrid-Vlasov Vlasiator simulation of the Earth's magnetosphere, showing the complex magnetic topologies created by reconnection. We also overview the dimensionalities of magnetic field structures in the simulation to support the use of such coordinate systems.

How to cite: Alho, M., Cozzani, G., Zaitsev, I., Kebede, F. T., Ganse, U., Battarbee, M., Bussov, M., Dubart, M., Hoilijoki, S., Kotipalo, L., Papadakis, K., Pfau-Kempf, Y., Suni, J., Tarvus, V., Workayehu, A., Zhou, H., and Palmroth, M.: Finding reconnection lines and flux rope axes via local coordinates in global ion-kinetic magnetospheric simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16113, https://doi.org/10.5194/egusphere-egu24-16113, 2024.

EGU24-16125 | Orals | ST2.1

Kelvin-Helmholtz Instability associated with reconnection and Ultra Low Frequency Waves at the ground 

Elena Kronberg, Jamie Gorman, Katariina Nykyri, Artem Smirnov, Jesper Gjerloev, Elena Grigorenko, Xuanye Ma, Karlheinz Trattner, and Matt Friel

The Kelvin-Helmholtz instability (KHI) and its effects related to the transfer of energy and mass from the solar wind into the magnetic environment of the Earth remain an important focus of magnetospheric physics. One such effect is the generation of Pc4-Pc5 ultra low frequency (ULF) waves at the ground. On July 3, 2007 at ∼0500 magnetic local time the Cluster space mission encountered Pc4 frequency Kelvin-Helmholtz waves (KHWs). Typically, KHI is thought to occur during the northward polarity of the interplanetary magnetic field and at low latitudes, however, the event occurred during a period of the southward polarity  according to the OMNI data and THEMIS observations at the subsolar point and at the high latitude magnetopause. Several of the KHI vortices were associated with magnetic field reconnection. Global magnetohydrodynamic simulation of the event confirmed the generation of KHWs at the magnetopause. The observed KHWs associated with reconnection coincided with recorded ULF waves at the ground whose properties suggest that they were driven by those waves. 

How to cite: Kronberg, E., Gorman, J., Nykyri, K., Smirnov, A., Gjerloev, J., Grigorenko, E., Ma, X., Trattner, K., and Friel, M.: Kelvin-Helmholtz Instability associated with reconnection and Ultra Low Frequency Waves at the ground, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16125, https://doi.org/10.5194/egusphere-egu24-16125, 2024.

EGU24-16135 | ECS | Posters on site | ST2.1 | Highlight

Vlasiator in 6D: magnetosphere-ionosphere coupling upgrades and automatic global flux rope identification 

Yann Pfau-Kempf and the Vlasiator team

We present recent and upcoming upgrades to the coupled ionosphere model now included in the global hybrid-Vlasov magnetospheric simulation Vlasiator. The handling of the magnetic field at the boundary has been corrected. The model used to obtain the parameterized precipitating electron fluxes is being upgraded to a more modern and flexible approach, and that new model is applied to obtain the precipitating proton fluxes from their velocity distribution function at the coupling radius in the hybrid-Vlasov domain.

Benefiting from the development of efficient runtime tracing of the magnetic field at the highest resolution, magnetic connectivity information is available at every point in the simulation, at every step. This information allows fast identification of the major domains of the near-Earth environment. Using magnetic field connectivity information we also introduce a novel approach to automatically and comprehensively detect magnetic flux rope structures of any scale and spatial orientation in the whole simulation domain.

How to cite: Pfau-Kempf, Y. and the Vlasiator team: Vlasiator in 6D: magnetosphere-ionosphere coupling upgrades and automatic global flux rope identification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16135, https://doi.org/10.5194/egusphere-egu24-16135, 2024.

EGU24-16333 | Posters on site | ST2.1

Probing the link between interplanetary magnetic field directional changes and bow shock geometry using simultaneous Cluster-MMS observations 

Costel Munteanu, Eliza Teodorescu, Marius Echim, Gabriel Voitcu, Maximilian Teodorescu, Cătălin Negrea, and Daniel Dumitru

We compiled a catalogue of 117 simultaneous Cluster-MMS magnetosheath crossings in 2017-2021 (http://www.spacescience.ro/projects/twister). The catalogue includes estimates of bow shock orientation for each event. Assuming that the bow shock normal direction does not change significantly during the magnetosheath crossing duration, we estimate the time evolution of θBn as the angle between the 1-minute time-resolution OMNI interplanetary magnetic field (IMF) and the estimated bow shock normal, and we calculate percentages of quasi-perpendicular (45°< θBn <135°) versus quasi-parallel (0°< θBn <45° or 135°< θBn <180°) bow shock orientations for each magnetosheath crossing. Ideally, if 45°< θBn <135° for the entire set of magnetosheath observations, that crossing would be considered “purely” quasi-perpendicular. Instead, we find that most magnetosheath crossings in our catalogue can be classified as “mixed”, i.e.  the bow shock orientation changes from quasi-perpendicular to quasi-parallel during the event. The assumption that the bow shock normal remains constant, implies that all changes of θBn characterising the mixed events are due to changes of IMF direction. To quantify this, we identify and catalogue IMF directional discontinuities during each event, using the algorithm described in Dumitru and Munteanu (2023) (https://doi.org/10.1029/2023EA002960). We present the results of the discontinuity detection algorithm and we probe the effect/role of IMF directional changes on our estimations of bow shock orientation.

How to cite: Munteanu, C., Teodorescu, E., Echim, M., Voitcu, G., Teodorescu, M., Negrea, C., and Dumitru, D.: Probing the link between interplanetary magnetic field directional changes and bow shock geometry using simultaneous Cluster-MMS observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16333, https://doi.org/10.5194/egusphere-egu24-16333, 2024.

EGU24-16339 | ECS | Orals | ST2.1

A Radial Standing Pc5-6 Wave and Its Energy Coupling With Field Line Resonance Within the Dusk-Sector Magnetosphere 

Zhou Yi-Jia, He Fei, Zhang Xiao-Xin, Martin Archer, Lin Yu, Ma Han, Tian An-Min, Yao Zhong-Hua, Wei Yong, Ni Binbin, Liu Wenlong, Zong Qiu-Gang, and Pu Zu-Yin
Global ultra-low frequency (ULF) oscillations are believed to play a significant role in the mass,
energy, and momentum transport within the Earth's magnetosphere. In this letter, we observe a ∼1.2 mHz
radial standing wave in the dusk-sector magnetosphere accompanied by the field line resonance (FLR) on 16
July 2017. The frequency estimation from the simple box model also confirms the radial standing wave. The
essential characteristics of FLR are concurrently identified at the dusk-sector magnetosphere and the conjugated
ground location. Further, the radial standing wave dissipates energy into upper atmosphere to enhance the
local aurora by coupling itself to the FLR. The magnetospheric dominant 1.2/1.1 mHz ULF waves plausibly
correspond well with the discrete ∼1 mHz magnetosheath ion dynamic pressure/velocity oscillation, suggesting
this radial standing wave and FLR in the flank magnetosphere may be triggered by the solar-wind and/or
magnetosheath dynamic pressure/velocity fluctuations.

How to cite: Yi-Jia, Z., Fei, H., Xiao-Xin, Z., Archer, M., Yu, L., Han, M., An-Min, T., Zhong-Hua, Y., Yong, W., Binbin, N., Wenlong, L., Qiu-Gang, Z., and Zu-Yin, P.: A Radial Standing Pc5-6 Wave and Its Energy Coupling With Field Line Resonance Within the Dusk-Sector Magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16339, https://doi.org/10.5194/egusphere-egu24-16339, 2024.

EGU24-16718 | ECS | Orals | ST2.1

Remote, long-term auroral kilometric radiation observations as a geomagnetic indicator of substorm onset 

James Waters, Laurent Lamy, and John Coxon

Auroral kilometric radiation (AKR) is a cyclotron maser instability generated radio emission that occurs in the region above the auroral oval; the observed intensity increases with the growth rate of the instability, indicating an active source region and the presence of accelerated electrons, while the emission frequency is inversely proportional to the altitude of a source along a field line. Remote observations can thus provide a direct insight into the spatial development of the primary coupling region between the magnetosphere and ionosphere during energetic phenomena. During substorms in particular, the auroral acceleration region has been shown to increase in altitude and increase the low-frequency power of the AKR spectrum, particularly towards dusk (Morioka et al. 2007, Waters et al. 2022). However, AKR is beamed anisotropically, which makes it difficult to observe global variability of the emission when a spacecraft is not in an ideal position, namely at dayside local times.

With an automatic extraction of AKR observations from the Wind spacecraft, we have access to nearly 30 years of data from a variety of viewing positions. The latest 20 years of observations are made from the  dayside, near L1. To evaluate the efficacy of the AKR observations as an indicator of substorm dynamics and further constrain the visibility effects, we compare AKR bursts from Wind (Fogg, Jackman, Waters et al. 2022) to a published list of substorm events derived from the SuperMAG magnetometer network. We calculate the binary classification statistics in four local time sectors with more than 10 years of AKR observation. When evaluated over a 2 hour window, AKR bursts observed from the nightside and duskside have a good (> 0.6) recall of substorm events, while the duskside observations have a more favourable false alarm probability (< 0.4). Dayside observations have a high miss rate (~0.8), but a high specificity (> 0.9), thus exhibiting a reliable proxy for substorm activity. Observations from all local time sectors except the nightside have positive forecast skill as determined by the Heidke skill score. Occurrence distributions of AKR burst frequencies from each local time sector and event group highlight the components present in each local time sector. This work lays the foundations for further parameterisation of the visibility of AKR sources at different locations within the inner magnetosphere by Wind when observing from L1, where the effects of the frequency, magnetic local time and magnetic latitude of the source can be examined more finely. Such work is useful for providing context for past AKR observations, as well as for the interpretation of future radio observations (with the JUICE flyby of Earth, for example), observation scheduling or planning of future missions.

How to cite: Waters, J., Lamy, L., and Coxon, J.: Remote, long-term auroral kilometric radiation observations as a geomagnetic indicator of substorm onset, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16718, https://doi.org/10.5194/egusphere-egu24-16718, 2024.

EGU24-17183 | ECS | Orals | ST2.1

Evolution of Atmospheric Oxygen Escape on Earth since the Paleoproterozoic Era 

Maria Luisa Alonso Tagle, Romain Maggiolo, Herbert Gunell, Gael Cessateur, Johan De Keyser, Iannis Dandouras, Aline Vidotto, Caue Borlina, Claire Nicholson, Giovanni Lapenta, Viviane Pierrard, and Ann Carine Vandaele

Understanding atmospheric escape over geological timescales is essential to constrain the planet’s ability to retain its atmosphere and thus sustain life. Atmospheric particles are energized through solar radiation and plasma interactions between the solar wind, the Earth’s magnetosphere, and ionosphere, escaping through various mechanisms.

For Earth, several missions provided measurements of the oxygen escape rate. However, measurements are for current solar and planetary conditions that strongly differ from the past conditions (e.g. stronger solar wind, higher solar EUV radiation). The main challenge to estimate the past escape rate is to extrapolate current measurements to the past solar system environment.

Since the Great Oxidation Event, 2.45 Gyr. ago, there is a significant amount of oxygen in the atmosphere. The goal of this study is to assess the stability of oxygen on Earth concerning atmospheric escape. We developed a semi-empirical model, which considers seven different escape mechanisms to estimate the net oxygen escape on Earth since this event. We use models available in the literature to describe the past solar wind and solar radiation, the Earth’s magnetic moment history, and the Earth’s exosphere evolution due to the change of solar EUV radiation while considering a constant atmospheric composition. The escape rate is calculated for these previous conditions considering a physical scaling and/or empirical formulas per mechanism.

We estimate that the total oxygen loss during the last 2.45 Gyr., reaches almost 30% of the current atmospheric oxygen content. Oxygen escape is dominated by polar processes, polar wind and cusp escape, contributing over 90% of the total loss. Polar wind is the leading erosion mechanism before ~1.5 Gyr. while escape from the polar cusp dominates at present.

How to cite: Alonso Tagle, M. L., Maggiolo, R., Gunell, H., Cessateur, G., De Keyser, J., Dandouras, I., Vidotto, A., Borlina, C., Nicholson, C., Lapenta, G., Pierrard, V., and Vandaele, A. C.: Evolution of Atmospheric Oxygen Escape on Earth since the Paleoproterozoic Era, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17183, https://doi.org/10.5194/egusphere-egu24-17183, 2024.

EGU24-17375 | ECS | Orals | ST2.1

Impact of Interplanetary Coronal Mass Ejections (ICME) on the geomagnetic tail from THEMIS observations 

Soboh Alqeeq, Dominique Fontaine, Olivier Le Contel, Mojtaba Akhavan-Tafti, Emanuele Cazzola, and Tsige Atilaw

We focus on a well-defined interplanetary coronal mass ejection (ICME) with a dynamic pressure Pdyn > 20 nPa, in December 2015. ACE observations and OMNI data allowed to identify ahead of Earth the expected features with shock and sheath regions preceding a magnetic cloud. This ICME triggered a storm in the magnetosphere with a storm sudden commencement (SSC) phase (SYM‐H ~ +50 nT) followed by a growth phase (SYM‐H < −150 nT at the minimum) and a long recovery phase lasting several days.

We investigate the global impact of this ICME on the Earth's magnetotail from observations by the NASA mission THEMIS. Indeed we estimate the total pressure exerted on the magnetotail current sheet. We find that the current sheet is compressed to ~ >2nP in the main phase, i.e. 4 times more than in the quiet phase before the event. In contrast, the pressure gradually decreases in the recovery phase and approximately comes back towards quiet phase values. According to the tracking of magnetic field lines using the Tsyganenko T96 magnetic field model, the current sheet appears stretched right from the SSC phase, and even more than during the main phase, before returning progressively to a shape comparable to the quiet phase. We quantify and discuss these effects to provide a more precise description of the magnetospheric geomagnetic activity during solar events.

How to cite: Alqeeq, S., Fontaine, D., Le Contel, O., Akhavan-Tafti, M., Cazzola, E., and Atilaw, T.: Impact of Interplanetary Coronal Mass Ejections (ICME) on the geomagnetic tail from THEMIS observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17375, https://doi.org/10.5194/egusphere-egu24-17375, 2024.

EGU24-17645 | Posters on site | ST2.1 | Highlight

Unveiling plasma energization and energy transport in the Earth’s Magnetospheric System through multi-scale observations: the science of the Plasma Observatory mission 

Alessandro Retinò and Maria Federica Marcucci and the Plasma Observatory Team

Energetic plasma is everywhere in the Universe. We observe plasma energization and energy transport in a variety of cosmic plasmas, such as planetary magnetospheres, stellar coronae, supernova remnant shocks, accretion disks, and astrophysical jets. The Earth’s Magnetospheric System is a key example of a complex and highly dynamic cosmic plasma environment where massive energy transport and plasma energization occur and can be directly studied through in situ spacecraft measurements. Despite the large amount of available in situ observations, however, we still do not fully understand how plasma energization and energy transport work. This is essential for understanding how our planet works, including space weather science, and is also important for the comprehension of distant astrophysical plasma environments. In situ observations, theory and simulations suggest that the key physical processes driving energization and energy transport occur where plasma on fluid scales couple to the smaller ion kinetic scales, at which the largest amount of electromagnetic energy is converted into energized particles. Remote observations currently cannot access these scales, and existing multi-point in situ observations do not have a sufficient number of observation points. Plasma Observatory will be the first mission having the capability to resolve scale coupling in the Earth’s Magnetospheric System through measurements of fields and particles at seven points in space, covering simultaneously ion and fluid scales in the Key Science Regions where the strongest plasma energization and energy transport occurs: the foreshock, bow shock, magnetosheath, magnetopause, magnetotail current sheet, and transition region. By resolving scale coupling in fundamental plasma processes such as shocks, magnetic reconnection, waves and turbulent fluctuations, plasma jets, field-aligned currents and plasma instabilities, these measurements will allow us to answer the two Plasma Observatory science questions (Q1) How are particles energized in space plasmas ? and (Q2) Which processes dominate energy transport and drive coupling between the different regions of the Earth’s Magnetospheric System? Plasma Observatory will also address important additional science targets such effects of ionospheric processes on the Magnetospheric System (e.g. ion outflows), outer radiation belts processes, solar wind physics and space weather science, which will increase  the scientific return of the PO mission. Going beyond the limitations of current ESA/Cluster and NASA/MMS four-point constellations, which can only resolve plasma processes at individual scales, Plasma Observatory will  transform our understanding of the plasma environment of our planet with a major impact on the understanding of astrophysical plasmas too.

How to cite: Retinò, A. and Marcucci, M. F. and the Plasma Observatory Team: Unveiling plasma energization and energy transport in the Earth’s Magnetospheric System through multi-scale observations: the science of the Plasma Observatory mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17645, https://doi.org/10.5194/egusphere-egu24-17645, 2024.

EGU24-18081 | ECS | Posters on site | ST2.1

Signature of Alfvénic and compressive waves in corotating Solar Wind high-speed streams on low-frequency geomagnetic activity at high latitudes 

Giuseppina Carnevale, Mauro Regi, Patrizia Francia, Stefania Lepidi, and Domenico Di Mauro

In the Solar Wind (SW), when a fast stream overtakes a slower one, it forms a corotating high-speed stream (HSS) with an upstream corotating interaction region (CIR) and a downstream rarefaction region (RR). The SW speed and the interplanetary magnetic field (IMF) exhibit wide fluctuations within CIRs and HSSs, that may have effects on the geomagnetic activity. Our study aims to investigate the effects of Alfvénic and compressive low-frequency fluctuations within SW corotating streams at 1 AU on geomagnetic activity in the low-frequency range (Pc5, 1-7 mHz), as observed at high-latitude geomagnetic observatories in both hemispheres. We analyzed several corotating streams, which were analyzed together with the corresponding geomagnetic field data recorded at ground observatories at high latitudes. For each observatory, we estimated a long-term geomagnetic power background in correspondence with quiet geomagnetic activity periods (low Kp index); then, we re-scaled the power to the background to better highlight the geomagnetic variations during the selected events. For SW data, we rotated the IMF and SW velocity components at 1AU into the Mean ElectroMagnetic Field Aligned (MEMFA) reference frame to identify fluctuation along two main directions: one aligned and one orthogonal to the ambient magnetic field. We compared the re-scaled geomagnetic field power with SW parameters, such as the power of IMF and SW velocity along the two directions, as well as with two quadratic invariants used to describe MHD turbulence: the normalized cross-helicity and the normalized residual energy. This combined method helps distinguish between compressive and Alfvénic fluctuations, providing insights into their impact on low-frequency geomagnetic variations.

How to cite: Carnevale, G., Regi, M., Francia, P., Lepidi, S., and Di Mauro, D.: Signature of Alfvénic and compressive waves in corotating Solar Wind high-speed streams on low-frequency geomagnetic activity at high latitudes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18081, https://doi.org/10.5194/egusphere-egu24-18081, 2024.

The transformation of the electromagnetic fields in different frames of reference (wether inertial reference frames or non-inertial reference frames) is the problem frequently met during the electromagnetic measurements in space and the relative analysis. For example, to draw the values of the electromagnetic fields in spacecraft comoving reference frame from the electromagnetic fields measured in the spacecraft rotational reference frame with a reasonable accuracy. Another example is the calculation of the charge density based on the four-point electrostatic field observations of MMS; the present analysis is not very satisfactory and there is still no rigid evaluation on the method applied. However, it is not easy to find a plain and rigid evaluation on the transformation formulas used. In this research, a systematic theoretic investigation has been performed, the universal formulas for the transformation are given and further applied to two actual situations successfully. For space plasmas, the relative velocities of the structures are generally very low and always much less than the speed of light in vacuum, so that the Galillia transformations are applicable. In this study, the Galillia transformations of the electromagnetic fields, the electric potential and magnetic vector potential, and the charge density and current density in different reference frames (wether inertial reference frames or non-inertial reference frames) have been presented and the respective errors are given. The results can find wide applications in space physics. At first, the general formula for the rotational potential of the planets are obtained. Secondly, by using the yielded theoretical results, a strict verification on the deduction of the charge density based on MMS electrostatic fields measurements has been made. It is found that, the Poisson equation is valid because the Coulomb gauge can be used for low-speed motions, and it is enough to draw the charge density from the MMS electrostatic fields measurements with a first order relative error. 

How to cite: Shen, C. and Ji, Y.: Transformations of the Electromagnetic Field in Different Frames of Reference and the Applications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20221, https://doi.org/10.5194/egusphere-egu24-20221, 2024.

EGU24-21617 | ECS | Posters on site | ST2.1

Supervised Machine Learning Algorithm to Classify Interplanetary Directional Discontinuities 

Daniel Dumitru, Costel Munteanu, Catalin Negrea, and Marius Echim

Directional discontinuities (DDs) are defined as abrupt changes of the magnetic field orientation. We use observations from ESA’s Cluster mission to compile a database of 4216 events identified in January-April 2007 and 5194 events from January-April 2008. Localized time-scale images depicting angular changes are created for each event, and a preliminary classification algorithm is designed to distinguish between: simple - isolated events, and complex - multiple overlapping events. In 2007, 1806 events are pre-classified as simple, and 2410 as complex; in 2008, 1997 events are simple, and 3197 are complex.  A supervised machine learning approach is used to recognize and predict these events. Two models are trained: one for 2007, which is used to predict the results in 2008, and vice versa for 2008. To validate our results, we investigate the discontinuity occurrence rate as a function of spacecraft location. When the spacecraft is in the solar wind, we find an occurrence rate of similar to 2 DDs per hour and a 50/50% ratio of simple/complex events. When the spacecraft is in the Earth's magnetosheath, we find that the total occurrence rate remains around 2 DDs/hr, but the ratio of simple/complex events changes to similar to 25/75%. This implies that about half of the simple events observed in the solar wind are classified as complex when observed in the magnetosheath. This demonstrates that our classification scheme can provide meaningful insights, and thus be relevant for future studies on interplanetary discontinuities. Parts of this research were published in AGU Earth and Space Science: Dumitru and Munteanu (2023), https://doi.org/10.1029/2023EA002960.



How to cite: Dumitru, D., Munteanu, C., Negrea, C., and Echim, M.: Supervised Machine Learning Algorithm to Classify Interplanetary Directional Discontinuities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21617, https://doi.org/10.5194/egusphere-egu24-21617, 2024.

EGU24-1264 | Orals | ST2.3

Simulation Study of Whistler-Mode Chorus Wave Generation in the Earth's Inner Magnetosphere 

Xueyi Wang, Yoshiharu Omura, Huayue Chen, Yikai Hsieh, Yu Lin, and Lunjin Chen

Whistler-mode chorus waves play an important role to control electron dynamics in the Earth’s radiation belt. Most of the existing theoretical and simulation studies on the chorus waves assume a one-dimensional field-aligned wave propagation. Physics of the chorus wave excitation and evolution in the multi-dimensional dipole field geometry still remains a challenge. The oblique propagation will be subject to wave attenuation at higher latitudes and introduce additional harmonic resonances. We have conducted simulations of two-dimensional chorus waves excited by hot anisotropic electrons interacting with cold dense plasma in a dipole magnetic field. It is found that the rising tone element of chorus waves with frequency chirping from low frequency to up to higher than the half electron gyro-frequency is generated at low latitudes. As the chorus wave propagates toward high latitudes, the wave becomes oblique and both the Landau and cyclotron resonance become significant. Two bands chorus waves are thus formed. In addition, we have found that a strong wave-particle interaction process presents in multi-dimensional electron distribution during the formation of chorus wave subpackets. The nonlinear physics associated with the wave growth and wave frequency chirping has been quantitatively evaluated in the process of chorus wave development.

How to cite: Wang, X., Omura, Y., Chen, H., Hsieh, Y., Lin, Y., and Chen, L.: Simulation Study of Whistler-Mode Chorus Wave Generation in the Earth's Inner Magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1264, https://doi.org/10.5194/egusphere-egu24-1264, 2024.

EGU24-1352 | Orals | ST2.3 | Highlight

Ultra-relativistic 7 MeV electron acceleration during intense and long-duration substorm activity 

Rajkumar Hajra, Bruce Tsurutani, Quanming Lu, Gurbax Lakhina, and Aimin Du

Substorms and strong convection events occurring during high-intensity long-duration continuous auroral electrojet (AE) activity (HILDCAA) events are associated with acceleration of magnetospheric relativistic electrons. From an analysis of Van Allen Probe satellite measurements, it is shown that ~7 MeV electrons are accelerated during ~3.4–4.1 days-long HILDCAA events. The dominant acceleration process is due to wave-particle interactions between magnetospheric electromagnetic chorus waves and substorm injected ~100 keV electrons. The longer the HILDCAA and chorus last, the higher the maximum energy of the accelerated relativistic electrons. The acceleration to higher and higher energies is by a bootstrap mechanism. Due to the unusually long process associated with the electron acceleration to ~7 MeV, spacecraft controllers can be given proper advance warning to shift to other modes of operation for the protection of spacecraft electronics.

How to cite: Hajra, R., Tsurutani, B., Lu, Q., Lakhina, G., and Du, A.: Ultra-relativistic 7 MeV electron acceleration during intense and long-duration substorm activity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1352, https://doi.org/10.5194/egusphere-egu24-1352, 2024.

Magnetosonic (MS) waves are common plasma waves in the Earth's magnetosphere. The self-consistent excitation of MS waves has been studied by 2D particle-in-cell simulations in the meridian and equatorial planes of a dipole magnetic field. However, the direction of wave propagation is artificially limited in the previous 2D simulations. Therefore, the 3D simulation of MS waves needs to be investigated. In this study, we investigate the excitation and evolution of MS waves in the Earth's dipole magnetic field based on a 3D general curvilinear particle-in-cell simulation. We find that the MS waves are excited primarily within 3° of the equator when the thermal velocity of the ring distribution is much less than the ring velocity of the ring distribution. These waves propagate along both the radial and azimuthal directions nearly perpendicular to the background magnetic field. In the linear stage, the growth rates of MS waves are almost equal in the radial and azimuthal directions. Compared with the waves propagating along the radial direction, the waves propagating along the azimuthal direction can grow for a longer time, resulting in a larger wave amplification in this direction after saturation. The simulation results provide a valuable insight to understand the self-consistent evolution of MS waves in the Earth's dipole magnetic field, and the findings are useful for understanding the plasma wave-particle interaction in the Earth's radiation belts.

How to cite: Sun, J.: Excitation and Propagation of Magnetosonic Waves in the Earth's Dipole Magnetic Field: 3D PIC Simulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2455, https://doi.org/10.5194/egusphere-egu24-2455, 2024.

EGU24-2493 | Orals | ST2.3

Observations and Analysis of MeV Electrons from REPT PHA Data and REPTile-2 data  

Xinlin Li, Declan O'Brien, Yang Mei, Zheng Xiang, and Daniel Baker

The Relativistic Electron-Proton Telescope (REPT) Pulse Height Analysis (PHA) data captures individual particle event for each of REPT’s nine silicon detectors onboard the Van Allen Probes. The PHA data set was taken every 12 milliseconds (ms), including the pulse height that is proportional to the energy deposit of each individual particle from all nine detectors. Geant4 simulations are used to extend and improve the electron detecting capabilities of REPT (beyond its nominal data) using the PHA data. After replicating the nominal characteristics of REPT in the Geant4 toolbox, new channels for REPT, going from 12 nominal electron channels to 47 and lowering the minimum energy to ~1 MeV, have been formulated. By applying these newly simulated electron channels to PHA data and combining with the detector singles rates, an estimated count rate data product for finer-resolution, lower-energy channels is created. This method enables higher resolution observations of electrons of 1.1 – 12 MeV, revealing more detailed characteristics of these high energy electrons in the magnetosphere, especially in the inner edge of the outer belt, slot region, and inner belt. Similarly, Relativistic Electron and Proton Telescope integrated little experiment -2 (REPTile-2) onboard Colorado Inner Radiation Belt Experiment (CIRBE), launched on 15 April 2023 into a low Earth orbit (LEO), has implemented PHA processing onboard, measuring 0.25 – 6 MeV electrons in 60 channels and protons in 60 channels and revealing detailed structures of the energetic electrons and protons, especially in the inner belt.

How to cite: Li, X., O'Brien, D., Mei, Y., Xiang, Z., and Baker, D.: Observations and Analysis of MeV Electrons from REPT PHA Data and REPTile-2 data , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2493, https://doi.org/10.5194/egusphere-egu24-2493, 2024.

EGU24-2562 | Orals | ST2.3

Banana Current in the Inner Magnetosphere Observed by Van Allen Probes 

Xiao-Xin Zhang, Tonghui Wang, Fei He, Jingtian Lv, Qiugang Zong, and Huishan Fu

By using the magnetic field data from Van Allen Probes, we analyzed the distribution characteristics of the electromagnetic environment in the inner magnetosphere on different Dst* index and magnetic local time. Our results show that for the response of different current systems, the dawn-dusk and noon-midnight asymmetry distribution of the residual magnetic field δB increases with Dst* index. When Dst* < −60 nT, a “banana”-shaped geomagnetic field negative disturbance peak region appears in the sector from midnight to dusk. Then, we obtained the azimuthal current density and found the asymmetric internal eastward and external westward ring current. Through the vector analysis of three-dimensional current density, the current density vector distribution in the magnetic equatorial plane is completely displayed for the first time, which directly proves the existence of banana current near r = 3.0–4.0 RE during strong geomagnetic storms.

How to cite: Zhang, X.-X., Wang, T., He, F., Lv, J., Zong, Q., and Fu, H.: Banana Current in the Inner Magnetosphere Observed by Van Allen Probes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2562, https://doi.org/10.5194/egusphere-egu24-2562, 2024.

EGU24-2660 | ECS | Orals | ST2.3 | Highlight

Understanding the inner magnetospheric drivers of the geospace plume evolution through magnetosphere-ionosphere coupling 

Shanshan Bao, Wenbin Wang, Kareem Sorathia, Viacheslav Merkin, Frank Toffoletto, Dong Lin, Kevin Pham, Jeffrey Garretson, Michael Wiltberger, John Lyon, and Adam Michael

The geospace plume, referring to the combined processes of the plasmaspheric and the ionospheric storm-enhanced density (SED)/total electron content (TEC) plumes, is one of the unique features of geomagnetic storms. The apparent spatial overlap and joint temporal evolution between the plasmaspheric plume and the equatorial mapping of the SED/TEC plume indicate strong magnetospheric-ionospheric coupling. However, a systematic modeling study of the factors contributing to geospace plume development has not yet been performed due to the lack of a sufficiently comprehensive model including all the relevant physical processes. In this paper, we present a numerical simulation of the geospace plume in the March 31, 2001 storm using the Multiscale Atmosphere Geospace Environment model. The simulation reproduces the observed linkage of the two plumes, which, we interpret as a result of both being driven by the electric field that maps between the magnetosphere and the ionosphere. The model predicts two velocity channels of sunward plasma drift at different latitudes in the dusk sector during the storm main phase, which are identified as the sub-auroral polarization streams (SAPS) and the convection return flow, respectively. The SAPS is responsible for the erosion of the plasmasphere plume and contributes to the ionospheric TEC depletion in the midlatitude trough region. We further find the spatial distributions of the magnetospheric ring current ions and electrons, determined by a delicate balance of the energy-dependent gradient/curvature drifts and the E´B drifts, are crucial to sustain the SAPS electric field that shapes the geospace plume throughout the storm main phase.

How to cite: Bao, S., Wang, W., Sorathia, K., Merkin, V., Toffoletto, F., Lin, D., Pham, K., Garretson, J., Wiltberger, M., Lyon, J., and Michael, A.: Understanding the inner magnetospheric drivers of the geospace plume evolution through magnetosphere-ionosphere coupling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2660, https://doi.org/10.5194/egusphere-egu24-2660, 2024.

EGU24-2776 | Posters on site | ST2.3 | Highlight

Response of Electric Field in Terrestrial Magnetosphere to Interplanetary Shock 

Wenlong Liu, Dianjun Zhang, Xinlin Li, and Theodore Sarris

Electric field impulses generated by interplanetary shocks can cause a series of dynamic processes in the Earth's magnetosphere and were previously explained by either fast-mode wave propagation or flow related to compression of the magnetopause. Based on a Space Weather Modeling Framework simulation, we suggest a new scenario in which the evolution of the impulse is due to both the propagation of the fast-mode wave and the compression of the magnetopause, which can explain the simulation and observations in previous related studies. The onset of the electric field impulse is determined by the propagation of the fast-mode wave in the magnetosphere while the peak of the impulse is determined by the propagation of the compression of the magnetopause. The new understanding of the impulse is important for the generation of subsequent ultralow frequency waves through the coupling of the fast-mode to Alfvén waves and field line resonances and related radiation-belt electron acceleration.

How to cite: Liu, W., Zhang, D., Li, X., and Sarris, T.: Response of Electric Field in Terrestrial Magnetosphere to Interplanetary Shock, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2776, https://doi.org/10.5194/egusphere-egu24-2776, 2024.

The most energetic electrons exceeding energies of 7 MeV are observed in the Earth’s outer radiation belt. In the past, numerical models of the radiation belts fell short to reproduce the acceleration to these ultra-relativistic energies, while the main acceleration process remains a debated topic.

In this work, we use the VERB-4D (Versatile Electron Radiation Belt) model to examine a geomagnetic storm that occurred on April 20th, 2017 to investigate the acceleration of electrons to ultra-relativistic energies. Using the observations from NASA’s Van Allen Probes spacecraft and quasi-linear plasma theory, we show that such acceleration is achievable only under extremely low plasma density conditions. The full 3-D simulation with a statistical model of plasma density fails to reproduce the acceleration to such high energies, whereas the simulation with plasma density variations taken from observations successfully reproduces the observed energization to ultra-relativistic energies at all radial location.

This study demonstrates the intricate interplay between the cold plasma and the acceleration of electrons to ultra-relativistic energies, and showcases our improved understanding of the high energy particle population.

How to cite: Haas, B., Shprits, Y., and Wang, D.: Modelling the acceleration of radiation belt electrons to ultra-relativistic energies during a geomagnetic storm using VERB-4D, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3974, https://doi.org/10.5194/egusphere-egu24-3974, 2024.

EGU24-4226 | ECS | Orals | ST2.3

Observational Analysis of In Situ Ring Current Density: A Multi-Mission, Multi-Perspective, and Multi-Spacecraft Approach 

Xin Tan, Malcolm Dunlop, Yanyan Yang, Junying Yang, and Christopher Russell

We systematically compare and analyze diverse methodologies for calculating space current density, with a particular focus on examining the insights and challenges associated with the Curlometer method. Employing these methodologies, we conduct an in-depth analysis of an event characterized by elevated calculated current densities, delving into its physical authenticity. Statistical analysis of the long-term measurements of particle and magnetic field values from multiple missions is also employed to investigate the distribution characteristics of current density within the ring current region. Despite the inherent limitations in the available data coverage, which preclude a comprehensive revelation of the spatial topology of the entire ring current, our preliminary findings indicate a season-dependent warping structure in the ring current, in both latitude and local time. This structural variation is fundamentally attributed to the combined influence of the Earth dipole field tilt and solar wind. These results are anticipated to contribute to the understanding of magnetospheric current systems, particularly elucidating the coupling mechanisms between the ring current and other current systems.

How to cite: Tan, X., Dunlop, M., Yang, Y., Yang, J., and Russell, C.: Observational Analysis of In Situ Ring Current Density: A Multi-Mission, Multi-Perspective, and Multi-Spacecraft Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4226, https://doi.org/10.5194/egusphere-egu24-4226, 2024.

EGU24-4512 | ECS | Orals | ST2.3

Ionospheric responses modulated by quasi-periodic EMIC waves associated with ULF waves 

Longxing Ma, Yiqun Yu, Xin Tong, Linhui Tang, Wenlong Liu, Jinbin Cao, Jun Wu, and Jian Wu
Energetic protons can be efficiently scattered by electromagnetic ion cyclotron (EMIC) waves into the upper atmosphere. This process represents a crucial mechanism for the exchange of energy and particles between the magnetosphere and ionosphere. In this study, quasi-periodic EMIC waves induced by Pc4 ULF waves were observed by the Van Allen Probes (RBSP) B satellite during a magnetic storm event on September 8, 2017. The associated pitch angle diffusion coefficient 𝐷𝛼𝛼 reveals that the quasi-periodic EMIC waves predominantly affect 30-100 keV protons. Concurrently, RBSP-B measurements indicated a remarkable quasi-periodic enhancement in the proton flux near the loss cone, with a frequency consistent with EMIC wave packets. Observations from the NOAA-19 satellite exhibited a substantial increase in 30-100 keV proton precipitating fluxes. Periodic proton precipitation resulted in clearly quasi-periodic enhancements of electron density in the ionospheric E-region detected by the European Incoherent Scatter (EISCAT) radar.

How to cite: Ma, L., Yu, Y., Tong, X., Tang, L., Liu, W., Cao, J., Wu, J., and Wu, J.: Ionospheric responses modulated by quasi-periodic EMIC waves associated with ULF waves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4512, https://doi.org/10.5194/egusphere-egu24-4512, 2024.

EGU24-4673 | ECS | Posters on site | ST2.3

The Effect of Different Loss Mechanisms on Ring Current Dynamics Based on The STRIM Model  

Ziming Wei, Yiqun Yu, and Longxing Ma

Charge exchange, Coulomb collisions, and field line curvature scattering (FLCS) are among the main loss mechanisms of the ring current during the recovery phase of a magnetic storm. Drifting around the Earth, ring current ions encouter charge exchange with neutral hydrogen from the geocorona, which results in the generation of high energy neutrals and low energy ions. As the energetic ring current particles pass through the thermal plasma, they are scattered due to the Coulomb collision, suffering energy loss and pitch angle diffusion. FLCS occurs when the ratio of the ion’s gyration radius to the curvature radius of the magnetic field line is large enough and chaotic scattering of the particles occurs. In this study, We propose a new method of calculating the diffusion coefficients in association with FLCS, which can be applied to a more stretched magnetic configuration. With the newly calculated diffusion coefficients, we investigate the effect of FLCS on ring current particles by using the Storm-Time Ring Current Model (STRIM) and compare its role with other ring current ion loss mechanisms like charge-exchange and Coulomb collisions. The ion lifetimes associated with these different loss mechanisms are compared to gain a deeper understanding of the impact of different mechanisms in the evolution of ring current. It is found that these mechanisms exert influences on different energies and pitch angles and their impacts also vary during different phases of the magnetic storm.

 

How to cite: Wei, Z., Yu, Y., and Ma, L.: The Effect of Different Loss Mechanisms on Ring Current Dynamics Based on The STRIM Model , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4673, https://doi.org/10.5194/egusphere-egu24-4673, 2024.

EGU24-4923 | Orals | ST2.3 | Highlight

Fine structures of magnetospheric magnetosonic waves: elementary rising-tone emissions and mini harmonics 

Jinxing Li, Jacob Bortnik, Sheng Tian, and Qianli Ma

The present study uncovers the fine structures of magnetosonic waves by investigating the EFW waveforms measured by Van Allen Probes. We show that each harmonic of the magnetosonic wave may consist of a series of elementary rising-tone emissions, implying a nonlinear mechanism for the wave generation. By investigating an elementary rising-tone magnetosonic wave that spans a wide frequency range, we show that the frequency sweep rate is likely proportional to the wave frequency. Furthermore, we reveal that each elementary rising-tone magnetosonic waves consist of multiple mini-harmonics spaced at O+ gyrofrequency. We reveal that O+ ions can suppress the generation of magnetosonic waves at multiples of O+ gyrofrequency, resulting in the mini-harmonic structure. The commonly observed mini-harmonics indicate an energy transfer between different ion species.

How to cite: Li, J., Bortnik, J., Tian, S., and Ma, Q.: Fine structures of magnetospheric magnetosonic waves: elementary rising-tone emissions and mini harmonics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4923, https://doi.org/10.5194/egusphere-egu24-4923, 2024.

Using Van Allen Probes observations spanning September 2012 to June 2019, we statistically investigate responses of electron phase space densities (PSDs) to 131 isolate storms in the Earth’s outer radiation belt. Electron PSDs for μ = 50-5000 MeV/G and K = 0.11 G1/2RE are calculated to evaluate three distinct responses (i.e., enhancement, depletion and no change), showing strong dependences on μ, L* and storm magnitude. Seed population is dominant by enhancement- and no change-type events, while relativistic and ultrarelativistic populations exhibit dynamical evolutions regardless of storm level. As μ increases, enhancement-type events decrease and tend to higher L*, while depletion-type events are increased for relativistic and ultrarelativistic populations. Comparing with small storms, large storms tangibly increase enhancement-type events at broader L* resulting in peak occurrences of relativistic population in the heart of the Earth’s other radiation belt. In contrast, large storms are likely decreasing ~20% depletion-type events for relativistic population and ~10% for ultrarelativistic population, as well as occurring at lower L*. No change-type events are primarily concentrated on inner part of the Earth’s other radiation belt, the L* coverages of which are sensitive to storm magnitude, especially for relativistic and ultrarelativistic populations. We also suggested that large storms are potentially accompanied by more intense solar and geomagnetic activities than small storms. While solar wind speed performs similarly for both storm levels and exhibits μ-dependent variations. Our results improve the current studies of storm-time electron PSD responses, thus providing a more comprehensive investigation to in-depth understanding dynamics of the radiation belt electrons during different storm levels.

How to cite: Wang, X., Cao, X., and Ni, B.: Responses of outer radiation belt electron phase space densities to geomagnetic storms: A statistical analysis based on Van Allen Probes observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5005, https://doi.org/10.5194/egusphere-egu24-5005, 2024.

EGU24-5036 | ECS | Posters on site | ST2.3

Statistical Study on the Azimuthal Mode Number of Pc5 ULF Wave in the Inner Magnetosphere 

Xin Tong, Wenlong Liu, Dianjun Zhang, Theodore Sarris, Xinlin Li, Zhao Zhang, and Li Yan

The azimuthal mode number, m, of ULF waves is a significant contributing factor for radiation belt electron energization, because it determines the conditions for resonant interaction between waves and particles. Based on multi-point magnetic field measurements of GOES satellites from January to September of 2011, we statistically analyze the distributions of the characteristics of m of Pc5 ULF waves. In the dayside, the local peaks in the distributions of wave power spectra density locate at ~10 and ~13 MLT for m < 0 (westward propagation) and m > 0 (eastward propagation) waves respectively, suggesting the waves generally propagate anti-sunward. In the nightside, the local peaks are at 22~23 MLT for both m < 0 and m > 0 waves, suggesting possible relation to substorm activities. Further investigation shows that, with increasing solar wind activities, the enhancements of dayside peaks are primarily contributed by m ≤ 3 waves, whereas the enhancements of nightside peak are contributed by both m ≤ 3 and m > 3 waves. With increasing AE index, the enhancements are more significant for the nightside peaks comparing to dayside peaks, and for m > 3 waves comparing to m ≤ 3 waves. The results of this study provide inputs for further investigation on the radial diffusion coefficient of radiation belt electrons with considering mode number information.

How to cite: Tong, X., Liu, W., Zhang, D., Sarris, T., Li, X., Zhang, Z., and Yan, L.: Statistical Study on the Azimuthal Mode Number of Pc5 ULF Wave in the Inner Magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5036, https://doi.org/10.5194/egusphere-egu24-5036, 2024.

EGU24-5079 | ECS | Posters on site | ST2.3

Estimating the Corotation Lag of the Plasmasphere Based on the Electric Field Measurements of the Van Allen Probes 

Zhao Zhang, Wenlong Liu, Dianjun Zhang, and Jinbin Cao

The corotation electric field driving the plasmasphere to corotate with the Earth body is important in establishing the topology of the inner magnetosphere and is usually calculated by assuming a 24 h corotation period. However, studies have found that a plasmasphere corotation lag exists, suggesting an overestimation of the electric field driving the plasmasphere to rotate with the planet in previous calculations. In this study, we use electric field measurements from the Van Allen Probes mission from 2012 to 2018 to obtain the distribution of the large-scale electric field in the inner magnetosphere. A new method is developed to extract plasmaspheric rotation information from electric field measurements. Our results show that the electric field driving the plasmaspheric rotation varies with magnetic activity, decreasing with increasing Kp index. It is thus suggested that the corotation lag of the plasmasphere is more significant during magnetically active periods.

How to cite: Zhang, Z., Liu, W., Zhang, D., and Cao, J.: Estimating the Corotation Lag of the Plasmasphere Based on the Electric Field Measurements of the Van Allen Probes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5079, https://doi.org/10.5194/egusphere-egu24-5079, 2024.

EGU24-5101 | ECS | Orals | ST2.3

Cluster Observation on the Latitudinal Distribution of Magnetic Pc5 Pulsations in the Inner Magnetosphere 

Li Yan, wenlong Liu, dianjun Zhang, Theodore E Sarris, Xinlin Li, Xin Tong, and Jinbin Cao
Ultralow frequency (ULF) waves in the Pc5 band are ubiquitous in the inner magnetosphere and can impact radiation belt dynamics by interacting with electrons through drift or drift-bounce resonance. In this paper, based on ∼ 19 years of Cluster measurements, we perform a comprehensive study of the three-dimensional distribution of poloidal, toroidal, and compressional ULF waves from L = 4 to 10, for magnetic latitudes (MLAT) up to Ultralow frequency ±50°, and in all magnetic local times (MLT). The distribution of the Pc5 ULF wave power is found to vary greatly as a function of L and MLT. For all L and MLT sectors, wave power of the poloidal and toroidal modes of the magnetic field increase with increasing MLAT, while the compressional mode decreases with increasing MLAT. The dawn–dusk asymmetries of wave power in poloidal and toroidal modes are more pronounced at higher MLAT. Furthermore, the wave power for Kp > 2 is approximately 2.93, 3.21, and 3.42 times greater than the wave power for Kp ≤ 2, respectively for compressional, poloidal and toroidal components. The information on the latitudinal distributions of ULF waves presented in this paper is important for future investigations on the radial diffusion process of radiation belt electrons with non-90° pitch angles while they bounce away from the magnetic equator.

How to cite: Yan, L., Liu, W., Zhang, D., Sarris, T. E., Li, X., Tong, X., and Cao, J.: Cluster Observation on the Latitudinal Distribution of Magnetic Pc5 Pulsations in the Inner Magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5101, https://doi.org/10.5194/egusphere-egu24-5101, 2024.

Whistler-mode waves play crucial roles in radiation belt dynamics, facilitating the acceleration of electrons from kiloelectron volts to megaelectron volts energy range and the loss of radiation belt electrons via wave-particle interaction. Recent studies suggest the important role of the duct propagation of whistler-mode waves for the radiation belt dynamics because the resonant energy increases to the relativistic energy in the high latitude region where ducting whistler-mode waves can reach. While the density duct caused by electron density structure has been studied for decades, it is evident from the dispersion relation that the refractive index is affected not only by the cold electron density but also by the magnetic field. We study the propagation of whistler-mode waves in ULF wave-derived magnetic ducts by two-dimensional ray-tracing simulations in the dipole coordinate system. We assume a magnetic duct structure at L=6 by considering the dipole field and a waveform of ULF wave oscillation with compressional and poloidal components. The refractive index fluctuations of the duct are calculated from the background field fluctuations caused by modeled compressible amplitudes associated with poloidal oscillations in the fundamental mode. The duct's shape is determined using a Gaussian function, and the rate of change of the magnetic field and the duct width are given parametrically. The refractive index structure is modeled every eighth of a ULF wave period, and the propagation of upper/lower-band frequency whistler-mode waves is simulated. Depending on the wave phase of the modeled ULF wave, the background magnetic field increases or decreases with each ULF phase, generating a depletion or enhancement duct. The simulation results show duct propagations, while the frequency where ducting of whistler-mode waves observed switches because the duct structure shifts with each phase of the modeled ULF wave. The duct width corresponds to the spatial scale of high-m ULF waves. A larger spatial scale can be expected if the ULF-induced plasma density variations are included. Furthermore, the duct propagation in other harmonics is also confirmed. This study reveals the characteristics of whistler-mode wave propagation by magnetic ducts due to ULF waves.

How to cite: Tachi, K. and Katoh, Y.: Propagation of whistler-mode waves in the magnetic duct caused by the compressional component of ULF wave oscillation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5125, https://doi.org/10.5194/egusphere-egu24-5125, 2024.

EGU24-5202 | ECS | Posters on site | ST2.3

The study on the distribution properties of NWC transmitter signals based on CSES observation 

Wang YaLu, Ni BinBin, Xu Wei, Zeren Zhima, Xiang Zheng, and Wang ZhongXing

Very-low-frequency (VLF) signals from ground-based transmitters could penetrate through the ionosphere, and even leak into the Earth's magnetosphere, leading to the precipitation of inner radiation belt electron. Therefore, detailed information about the distribution characteristics of VLF transmitter signals in geo-space is of great importance for in-depth understanding of their driven radiation belt electron loss processes and consequences. Based on data from DEMETER, CSES and Van-Allen Probes, the VLF signals emitted from NWC transmitter located in Australia, were analyzed firstly to validate CSES data. The we distinguished the NWC signals in the ionosphere and statistically investigate the day-night asymmetry, geographic distributions, seasonal and geomagnetic activity dependence, and wave propagation features, using the electric field measurements from CSES during the period from 2019 to 2022. The results indicated that, on the night-side and during the months of local winter, VLF transmitter signals are stronger due to the smaller ionosphere electron density. In contrast, the amplitudes of these signals are weakly affected by the level of geomagnetic activity. The distribution properties of NWC signals at the conjugate region, showed that the signals propagate to the conjugate hemisphere both in the non-ducted mode and ducted mode.

How to cite: YaLu, W., BinBin, N., Wei, X., Zhima, Z., Zheng, X., and ZhongXing, W.: The study on the distribution properties of NWC transmitter signals based on CSES observation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5202, https://doi.org/10.5194/egusphere-egu24-5202, 2024.

EGU24-5770 | ECS | Orals | ST2.3

Arase HEP-L electron measurement calibration and comparisons of pitch angle distributions with Van Allen Probes 

Milla Kalliokoski, Kazushi Asamura, Iku Shinohara, Takefumi Mitani, Tomoaki Hori, Yoshizumi Miyoshi, Nana Higashio, and Takeshi Takashima

The Arase satellite observes the dynamics of the Earth’s radiation belts, including the electron fluxes over a wide energy range from a few electronvolts to several MeV. This work focuses on the measurements of the Arase high-energy electron experiment (HEP), specifically its instrument HEP-L that observes electrons from 60 keV to 1.5 MeV. It is a state-of-the-art instrument capable of distinguishing the incoming direction of electrons by position sensitive detectors, thus accurately determining the pitch angle. HEP-L has been previously calibrated based on the modeled response functions of the instrument’s energy channels using Geant4 simulation. The current work utilizes the same simulation, but now considering the calibration in terms of the azimuthal channels, i.e., the direction of measured counts. As shown by the simulation, the distribution of counts in each azimuthal channel is broader than the nominal range in the initial direction angle, causing cross-channel contamination. We propose a new method to calibrate HEP-L data to diminish this contamination, and applying the correction method lowers the electron fluxes especially at field-aligned pitch angles, where uncorrected HEP-L data were overestimated, as seen in comparison with other instruments on board Arase and the Van Allen Probes. Pitch angle distributions (PADs) from Arase and Van Allen Probes were compared during close conjunctions of the spacecraft. Previous comparisons have only considered the omnidirectional fluxes which offer a limited view of the radiation belt dynamics. PADs provide a more detailed comparison and shed light on, e.g., wave-particle interactions. Here we derived PADs from HEP-L and extremely high-energy experiment (XEP) on Arase, and the Magnetic Electron Ion Spectrometer (MagEIS) and the Relativistic Electron-Proton Telescope (REPT) instruments on Van Allen Probes to cover a large energy range. There is a remarkable agreement within a factor of 2 for all energies, for all pitch angles for XEP data and for most pitch angles (20 to 160 degrees) for uncorrected HEP-L data. By applying the new correction, the discrepancy at the field-aligned pitch angles is reduced.

How to cite: Kalliokoski, M., Asamura, K., Shinohara, I., Mitani, T., Hori, T., Miyoshi, Y., Higashio, N., and Takashima, T.: Arase HEP-L electron measurement calibration and comparisons of pitch angle distributions with Van Allen Probes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5770, https://doi.org/10.5194/egusphere-egu24-5770, 2024.

EGU24-6588 | Orals | ST2.3

Hamiltonian approach to the electron resonant interaction with coherent ULF waves 

Dmitri Vainchtein, Anton Artemyev, and Xin An

Electron resonant interaction with ultra-low-frequency (ULF) waves is the one of the main drivers of the electron radial transport in the Earth's inner magnetosphere. Recent spacecraft observations reported a possibility for electrons to resonate nonlinearly with intense coherent ULF waves, way beyond traditional approach of a slow diffusive scattering of electrons by a broad-band ULF spectrum. In this study we propose a theoretical model describing key elements of such nonlinear resonant interactions. We adapted the Hamiltonian approach to describe equatorial electron motion in the dipole magnetic field and electric ULF wave field. We demonstrated the presence of two main regimes for ULF-electron interaction: the phase bunching and phase trapping. We discuss possible applications of the proposed theoretical approach and the importance of ULF-electron nonlinear resonance. 

How to cite: Vainchtein, D., Artemyev, A., and An, X.: Hamiltonian approach to the electron resonant interaction with coherent ULF waves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6588, https://doi.org/10.5194/egusphere-egu24-6588, 2024.

EGU24-6644 | Orals | ST2.3

On the field-aligned Poynting fluxes of plasmaspheric hiss 

Hui Zhu, Huicong Chen, and Mingyue Lu

In this study, we investigate Poynting fluxes of plasmaspheric hiss waves using the Van Allen Probes wave observation. The hiss waves are identified based on the number density of cold plasma, wave frequency, ellipticity, wave normal angle, and planarity. The statistical results show that on the dayside the Poynting flux magnitudes of the hiss waves are stronger than those on the nightside and their field-aligned components are much larger than the perpendicular components. We calculate the net Poynting flux direction Rs of hiss waves along field-aligned direction for different frequency ranges, under different geomagnetic activities, and in different MLT sectors, whose sign can indicate the balance between the growth and damping processes. We find that in the inner plasmasphere Rs is negative while in the outer plasmasphere Rs is positive and their transition locations significantly depend on wave frequency and geomagnetic activity. The results suggest that the local generation of hiss waves may be important in the outer plasmasphere. 

How to cite: Zhu, H., Chen, H., and Lu, M.: On the field-aligned Poynting fluxes of plasmaspheric hiss, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6644, https://doi.org/10.5194/egusphere-egu24-6644, 2024.

EGU24-7460 | Posters on site | ST2.3

Analytical Model of Magnetospheric Whistler Mode Waves Based on Cubic Splines 

Ondřej Santolík, Ivana Kolmašová, Ulrich Taubenschuss, Marie Turčičová, and Miroslav Hanzelka

We model the behavior of long-term averages of whistler mode waves in the inner magnetosphere as a function of position and geomagnetic activity. We analyze a combined data set of the Van Allen Probes and Cluster missions to construct empirical analytic expressions defined in a 4-dimensional parametric space of magnetic local time, absolute value of magnetic latitude, McIlwain's L parameter, and Kp index. We use a simple but sufficiently general functional form based on polynomial cubic splines with linear extrapolation outside of the approximation interval. The model clearly reproduces the strong influence of external driving in the equatorial region and a weak response of chorus amplitudes at high latitudes to the geomagnetic activity.

How to cite: Santolík, O., Kolmašová, I., Taubenschuss, U., Turčičová, M., and Hanzelka, M.: Analytical Model of Magnetospheric Whistler Mode Waves Based on Cubic Splines, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7460, https://doi.org/10.5194/egusphere-egu24-7460, 2024.

EGU24-7559 | ECS | Orals | ST2.3

Statistical Properties of Long-Period Plasmapause SurfaceWaves From Van Allen Probes Observations 

Zi-Jian Feng, Jie Ren, Qiu-Gang Zong, Ting-Yan Xiang, and Xin-Yu Ai

Recent work revealed the existence of plasmapause surface waves (PSWs) with Van Allen Probes observations, which are characterized by the periodic modulations of both magnetic/electric fields and plasma densities, and suggested to be the driver of giant undulations (GUs). In this study, six years data from Van Allen Probes were used to investigate the spatial distributions and occurrence conditions of PSWs in the period of 5–30 min. PSWs are found to be mainly distributed at L = 3.5–7 and their occurrence rate is increasing with larger L shells. In the azimuth direction, the spatial distribution of PSWs exhibits an obvious dawn-dusk asymmetry with highest occurrence rates at MLT = 15–21, which is consistent with the spatial distribution of GUs revealed in the previous study. This further demonstrates that PSWs and GUs are connected, and indicates that PSWs differ from Ps6 waves which have a similar wave period and irregular waveform but mainly concentrate in the dawnside and connect with Ω bands. PSWs preferentially occur under the condition of high solar wind velocities (VSW > 500 km/s) and high dynamic pressures (Pdyn > 5 nPa), and their occurrence rate has a negative correlation with IMF Bz, SYMH and AL. Statistical results also reveal that PSWs preferentially occur around the peak of both magnetic storms and substorms. These findings may shed new lights on the further understanding of PSWs' generation and propagation.

How to cite: Feng, Z.-J., Ren, J., Zong, Q.-G., Xiang, T.-Y., and Ai, X.-Y.: Statistical Properties of Long-Period Plasmapause SurfaceWaves From Van Allen Probes Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7559, https://doi.org/10.5194/egusphere-egu24-7559, 2024.

EGU24-7584 | ECS | Orals | ST2.3 | Highlight

Introducing a new ground-based Radiation belt electron enhancement events catalog 

Gautier Nguyen, Guillerme Bernoux, and Vincent Maget

Electron radiation belt enhancement events are a key phenomena of the Earth geomagnetic activity and have been thoroughly studied in the literature.

Establishing extensive catalogs of these events automatically is a key asset to both the global statistical study of the electron radiation belt enhancement and, from an operational perspective, to provide actionable scenario-based forecasts. The latter being the objective of the EU Horizon Europe FARBES (Forecast of Actionable Radiation Belts Scenarios) under which this work is funded.

Nowadays, the existing attempts of establishments of such catalogs are scarce and often based on the exceedance of certain thresholds of ground-based measurements (Bernoux and Maget, 2020) or onboard electron fluxes (Reeves et al. 2020). Which often leads to missed events, non-events or events with unrealistic boundaries.

In this work, we introduce a novel automatic detection method of radiation belt enhancement events based on the Ca index (Rochel et al. 2016), a simple 1D-proxy representative of the state of the electron radiation belts for average energies (up to  MeV). This method is then used to produce an extensive catalog of events between 1870 and 2023 with more realistic boundaries. The most recent events of this catalog (detected after 1995) are then associated with their possible physical cause, whether it be Interplanetary Coronal Mass Ejections (ICMEs) or Streaming-Interaction regions (SIRs).

How to cite: Nguyen, G., Bernoux, G., and Maget, V.: Introducing a new ground-based Radiation belt electron enhancement events catalog, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7584, https://doi.org/10.5194/egusphere-egu24-7584, 2024.

EGU24-8984 | Orals | ST2.3

Whistler-mode quasiperiodic emissions and magnetospheric line radiation: Fine inner structure 

František Němec, Ondřej Santolík, Jyrki Manninen, Claudia Martinez-Calderon, Kazuo Shiokawa, George B. Hospodarsky, and William S. Kurth

The intensity of magnetospheric whistler-mode waves at frequencies of a few kilohertz sometimes exhibits nearly periodic temporal or frequency modulation. Events exhibiting temporal modulation are typically referred to as quasiperiodic (QP) emissions, while those with frequency modulation are commonly known as magnetospheric line radiation (MLR). Although these events are rather routinely observed both by spacecraft and ground-based instruments, their exact formation mechanism is still not fully understood.

We use high-resolution burst mode data, measured by the Van Allen Probes spacecraft in the equatorial region at larger radial distances, by the low-altitude DEMETER spacecraft, and by the Kannuslehto and PWING ground-based instruments, to demonstrate and investigate the fine inner structure of these events. We show that such a fine inner structure is often present for both QP and MLR events. Detailed wave propagation and timing analysis reveals that it corresponds to the wave bouncing between the hemispheres. We discuss the possible implications of these observations for understanding the event formation mechanisms.

How to cite: Němec, F., Santolík, O., Manninen, J., Martinez-Calderon, C., Shiokawa, K., Hospodarsky, G. B., and Kurth, W. S.: Whistler-mode quasiperiodic emissions and magnetospheric line radiation: Fine inner structure, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8984, https://doi.org/10.5194/egusphere-egu24-8984, 2024.

EGU24-9152 | ECS | Posters on site | ST2.3

Diffusive and non-diffusive behavior of electron interaction with quasi-coherent and quasi-parallel chorus emissions 

Miroslav Hanzelka, Yuri Shprits, Dedong Wang, Bernhard Haas, Julia Himmelsbach, and Ondrej Santolik

Numerical models used to study the Earth’s outer radiation belt dynamics are often based on the diffusive Fokker-Planck equation derived from the quasilinear theory of wave-particle interactions. However, this stochastic approach fails at short time scales due to nonlinear interactions with high-amplitude waves, which can result in a rapid directional transport of particles in the phase space. An example of strong waves that facilitate nonlinear transport is the chorus emission, which often forms discrete, rising-tone elements with a high degree of phase coherence.

It is expected that after multiple resonant interactions of electrons with the chorus waves, the stochastic description of scattering becomes applicable. However, it is unclear how this convergence towards stochastic and diffusive behavior depends on the wave parameters. We, therefore, construct a realistic model of chorus elements parametrized by bandwidth, wave normal distribution, frequency range, and amplitude. With this model, we numerically investigate the evolution of electron pitch angle and energy over multiple bounces. We use the backward-in-time test-particle mapping of phase space density for each element separately, and obtain the long-term evolution with a variable train of chorus elements by combining the individual mappings. We analyze the onset of stochasticity in dependence on the wave parameters and compare the phase space density evolution with the VERB-2D (Versatile Electron Radiation Belt code) implementation of the diffusive Fokker-Planck equation.

How to cite: Hanzelka, M., Shprits, Y., Wang, D., Haas, B., Himmelsbach, J., and Santolik, O.: Diffusive and non-diffusive behavior of electron interaction with quasi-coherent and quasi-parallel chorus emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9152, https://doi.org/10.5194/egusphere-egu24-9152, 2024.

EGU24-9259 | ECS | Posters on site | ST2.3

Magnetospheric whistler-mode waves detected simultaneously by the DEMETER spacecraft and the Kannuslehto Station 

Kristyna Drastichova, František Němec, and Jyrki Manninen

Conjugate observations of magnetospheric whistler-mode waves provided by the DEMETER spacecraft at an altitude of about 660 km and the Kannuslehto station located near Sodankyla, Finland are analyzed. More than 500 DEMETER half-orbits between November 2006 and March 2008 overlap with the Kannuslehto data. The analysis includes waves at frequencies up to 16 kHz. We aim to determine the characteristic spatial scales of the waves and their propagation to the ground. For this purpose, correlations of wave intensities measured by both the spacecraft and the ground-based station are evaluated using two different approaches: i) direct correlations of wave intensities measured simultaneously at the same frequencies, and ii) correlations of wave patterns over a moving frequency-time window of a predefined size. The resulting correlations are studied as a function of the L-shell/geomagnetic longitude separation between the spacecraft and the ground-based station. The corresponding correlation lengths are determined as a function of frequency. Additionally, correlations of the wave intensities and the geomagnetic activity indices (Kp/AE) are calculated, demonstrating rather different dependence on the ground and at low altitudes.

How to cite: Drastichova, K., Němec, F., and Manninen, J.: Magnetospheric whistler-mode waves detected simultaneously by the DEMETER spacecraft and the Kannuslehto Station, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9259, https://doi.org/10.5194/egusphere-egu24-9259, 2024.

EGU24-9438 | ECS | Orals | ST2.3

The Excitation of Eastward Second Harmonic Poloidal Waves Through Drift-Bounce Resonance with Protons in the Magnetic Dip 

Yan Zhuang, Chao Yue, Li Li, Xu-Zhi Zhou, Qiu-Gang Zong, Xing-Yu Li, Ze-Fan Yin, Ying Liu, Haobo Fu, Zhi-Yang Liu, and Yong-Fu Wang

The drift-bounce resonance between ultralow-frequency (ULF) wave and charged particles is an efficient way to transfer energy. In this study, we report the excitation of ULF waves through drift-bounce resonance with protons in the magnetic dip for the first time. On 4 September 2015, Van Allen probe B observed ULF signals with a frequency of ~10 mHz inside the magnetic dip during substorms at the dusk side. The ULF waves are further diagnosed as second harmonic poloidal waves. The 54-67 keV protons in the magnetic dip exhibit oscillations with the same period as ULF waves, providing evidence for drift-bounce resonance. Through finite Larmor radius effects combined with simulations, we determined the ULF waves propagate eastward with an azimuthal wave number of ∼240. The sign of df/dW reveals that the ULF waves are excited and related to the outward radial gradient of proton phase space density. 

How to cite: Zhuang, Y., Yue, C., Li, L., Zhou, X.-Z., Zong, Q.-G., Li, X.-Y., Yin, Z.-F., Liu, Y., Fu, H., Liu, Z.-Y., and Wang, Y.-F.: The Excitation of Eastward Second Harmonic Poloidal Waves Through Drift-Bounce Resonance with Protons in the Magnetic Dip, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9438, https://doi.org/10.5194/egusphere-egu24-9438, 2024.

EGU24-11184 | ECS | Posters on site | ST2.3

Developing Chorus Wave Model Using Van Allen Probe and Arase Data 

Alwin Roy, Dedong Wang, Yuri Y Shprits, Ting Feng, Thea Lepage, Ingo Michaelis, Yoshizumi Miyoshi, Geoffrey D Reeves, Yoshiya Kasahara, Ondřej Santolik, Atsushi Kumamoto, Shoya Matsuda, Ayako Matsuoka, Tomoaki Hori, Iku Shinohara, and Fuminori Tsuchiya

Chorus waves play an important role in the dynamic evolution of energetic electrons in the Earth’s radiation belts and ring current. Due to the orbit limitation of Van Allen Probes, our previous chorus wave model developed using Van Allen Probe data is limited to low latitude. In this study, we extend the chorus wave model to higher latitudes by combining measurements from the Van Allen Probes and Arase satellite. As a first step, we intercalibrate chorus wave measurements by comparing statistical features of chorus wave observations from Van Allen Probes and Arase missions. We first investigate the measurements in the same latitude range during the two years of overlap between the Van Allen Probe data and the Arase data. We find that the statistical intensity of chorus waves from Van Allen Probes is stronger than those from Arase observations. After the inter-calibration, we combine the chorus wave measurements from the two satellite missions and develop an analytical chorus wave model which covers all magnetic local time and extends to higher latitudes. This chorus wave model will be further used in radiation belt and ring current simulations.

How to cite: Roy, A., Wang, D., Shprits, Y. Y., Feng, T., Lepage, T., Michaelis, I., Miyoshi, Y., Reeves, G. D., Kasahara, Y., Santolik, O., Kumamoto, A., Matsuda, S., Matsuoka, A., Hori, T., Shinohara, I., and Tsuchiya, F.: Developing Chorus Wave Model Using Van Allen Probe and Arase Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11184, https://doi.org/10.5194/egusphere-egu24-11184, 2024.

EGU24-14967 | ECS | Orals | ST2.3

ULF waves in geospace and the challenge of estimating radial diffusion coefficients from in situ data. 

Christos Katsavrias, Sigiava Aminalragia-Giamini, Konstantina Thanasoula, Afroditi Nasi, Constantinos Papadimitriou, Marina Georgiou, Georgios Balasis, and Ioannis A. Daglis

Radial diffusion, driven by Ultra-Low Frequency (ULF) waves in the Pc4–5 band (2–25 mHz), has been established as one of the most important mechanisms that influences the dynamics of electrons in a quite broad energy range, as it can lead to both energization and loss of relativistic electrons in the outer Van Allen radiation belt. The same has been observed in other planetary magnetospheres. The dependence of ULF wave power spectral density and radial diffusion coefficients (DLL) on solar wind parameters has been investigated by some studies, but their relationship on the various solar and interplanetary drivers is far from well-studied and understood. In this study, we use the “SafeSpace” database (https://synergasia.uoa.gr/modules/document/?course=PHYS120), which contains radial diffusion coefficients and ULF wave power spectral density, and was created using magnetic and electric field measurements from the THEMIS satellites in the 2011–2019 time-period. We conduct an extensive statistical analysis of DLL in order to investigate the relationships between the magnetic and electric components as well as their dependence on interplanetary drivers (i.e. High Speed Streams and Interplanetary Coronal Mass Ejections). Our results reveal an energy dependence of the radial diffusion coefficients as well as significant variations of the DLL spectral profiles as a function of Roederer’s L*. Our findings highlight statistical, as well as physical, characteristics and aspects of DLL which are not included in most semi-empirical models typically used in radiation belt simulations, thus potentially introducing significant biases in the estimation of the outer belt relativistic electron environment. Further discussion will be devoted to the uncertainties of such efforts as well as the possible contribution of magnetosheath processes (e.g., jets and electron injections from the foreshock) and solar wind mechanisms (periodic density structures).

The work leading to this paper has received funding from the European Union’s Horizon Europe research and innovation programme under grant agreement No 101081772 for the FARBES (Forecast of Actionable Radiation Belt Scenarios) project.

 

How to cite: Katsavrias, C., Aminalragia-Giamini, S., Thanasoula, K., Nasi, A., Papadimitriou, C., Georgiou, M., Balasis, G., and Daglis, I. A.: ULF waves in geospace and the challenge of estimating radial diffusion coefficients from in situ data., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14967, https://doi.org/10.5194/egusphere-egu24-14967, 2024.

EGU24-17306 | ECS | Posters on site | ST2.3

Versatile near-Earth environment of Radiation Belts and ring current 4D (VERB-4D) code 

Julia Himmelsbach, Yuri Shprits, Bernhard Haas, Matyas Szabo-Roberts, Dedong Wang, Hayley J. Allison, and Michael Wutzig

Ring current particles, which are heavily influenced by geomagnetic activity, excite plasmawaves (e.g., EMIC, chorus etc) and affect the terrestrial magnetospheric configuration, which modifies particle trajectories. During geomagnetic storms, specifically the recovery phase, the ring current becomes disturbed and decays via various loss processes (e.g., charge exchange, Coulomb collisions, and EMIC wave scattering). These disturbances in the ring current contribute significantly to the development of the Dst index. Since the ring current plays a crucial role in magnetospheric dynamics through its spatial and temporal evolution, understanding how it impacts the Dst index remains an ongoing topic of research.

In this study, we present the first simulation results of the ring current using the Versatile near-Earth environment of Radiation Belts and ring current - 4D (VERB-4D) code, previously known as the Versatile Electron Radiation Belt - 4D code. Our simulations are compared to the Van Allen Probes HOPE and RBSPICE during a geomagnetic storm on March 17, 2013. We study the evolution of the MLT-resolved and average Dst index during the storm‘s recovery phase while examining the relative contributions of charge exchange, Coulomb drag, and radial diffusion.

How to cite: Himmelsbach, J., Shprits, Y., Haas, B., Szabo-Roberts, M., Wang, D., Allison, H. J., and Wutzig, M.: Versatile near-Earth environment of Radiation Belts and ring current 4D (VERB-4D) code, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17306, https://doi.org/10.5194/egusphere-egu24-17306, 2024.

EGU24-17365 | ECS | Orals | ST2.3

Plasma wave occurrences during substorm events  

Trunali Shah, Veenadhari Bhaskara, Yoshiharu Omura, Biswajit Ojha, Satyavir Singh, and Yusuke Ebihara

The Earth's magnetosphere is a dynamic system subject to various disturbances, among which substorms play a significant role in influencing its impact on the surrounding plasma environment. Close to the substorm onset satellites flying in the night side often observe reconfiguration of magnetic field lines from tail like to quasi-dipole like. This phenomenon is called magnetic field dipolarization. Studying the particle and wave dynamics during this phenomenon is crucial to understand as it accelerates the ion population and alters the generation condition of waves associated with it. Using the Electric and Magnetic Field Instrument Suite (EMFISIS) onboard the Van Allen Probes spacecraft, the present study investigates the magnetic field fluctuations corresponding to substorm onset. We examine thirteen substorm occurrences with L < 6.6 and within wide a range of MLT (18:00 to 06:00). Our investigation reveals significant magnetic field fluctuations exhibiting power from gyrofrequency of O+ extending up to gyrofrequency of H+. We additionally calculate the plasma and magnetic pressures, providing insight into the mechanism triggering ion injection during these occurrences. The role of heavy ions (He+ and O+) in the disappearance of stop bands and the corresponding mechanisms involved in this phenomenon it will we presented.

How to cite: Shah, T., Bhaskara, V., Omura, Y., Ojha, B., Singh, S., and Ebihara, Y.: Plasma wave occurrences during substorm events , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17365, https://doi.org/10.5194/egusphere-egu24-17365, 2024.

EGU24-18156 | ECS | Posters on site | ST2.3

Global Validation of the Data-Assimilative VERB-3D code 

Marina García Peñaranda, Yuri Shprits, Angélica M. Castillo Tibocha, Alexander Drozdov, and Matyas Mátyás Szabó-Roberts

Radiation belt electron dynamics show high variability in space and time during geomagnetically active periods, which could potentially damage the satellites though deep dielectric and surface charging. In the past years, numerous physics-based models have been developed to describe the evolution of phase space density in the radiation belts, however they are subject to uncertainties and errors in the initial and boundary conditions. Data assimilation provides to be a reliable technique for blending satellite data and the output of physics-based models, creating a more reliable reconstruction with all the available information about the environment.

We present a preliminary global validation of the data-assimilative VERB-3D code for a geomagnetic event in September 2017. We assimilated Arase measurements into the VERB-3D code via a split-operator Kalman Filter, and validated the results against measurements obtained from the RBSP satellites.  The results provide very valuable insights into the accuracy and performance of the data assimilative model and its capability to replicate the radiation belt environment, showing the great potential for data assimilation techniques in space weather applications.

How to cite: García Peñaranda, M., Shprits, Y., Castillo Tibocha, A. M., Drozdov, A., and Mátyás Szabó-Roberts, M.: Global Validation of the Data-Assimilative VERB-3D code, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18156, https://doi.org/10.5194/egusphere-egu24-18156, 2024.

 Energetic Electron Dynamics are ones of the most dynamic processes in Earth's magnetosphere and have global consequences and broad implications for space weather. They can be monitored using energetic electron detectors on both Macao Science Satellites (MSS-1A/B) and sunsynchronous satellites (Fengyun 3E). There are triple Imaging Electron Spectrometer (IES)  instruments to be installed in the Macao Science Satellites and Chinese Sun-synchronous (FY3E) satellites, respectively. The IES instrument on board  both Macao Science Satellites and Chinese Meteorology FY-3 (sunsynchronous) satellite, launched on May, 2023, and 4 July, 2021 (FY-3)  into a sunsynchronous satellite orbit (LEO), provides the first  constellation eneregetic electron measurements in the inner Radiation Belt and SAA region. The Macau Scientific Satellite - 1 (MSS) comprises two satellites orbiting the Earth at an inclination of 41. MSS1-A follows a circular orbit at an altitude of 450 km, while MSS1-B's orbit is elliptical, ranging between 450 and 500 km in altitude, with its apogee positioned near the South Atlantic Anomaly (SAA). These two satellites share a similar orbit, maintaining a separation of approximately 5-10s minutes, which has varied since their launch. The orbital period for both satellites is approximately 94 minutes.  The innermost and outermost signatures of substorm injection have been observed by the IES instruments with a wide L shell spatial coverage, from L=1 ~ 6.  Such a configuration will provide a unique opportunity to investigate Energetic Electron Dynamics simultaneously at low and high  L shells. It will further elucidate potential mechanisms for the particle energization and transport, two of the most important topics in inner radiation belt dynamics.  

How to cite: Zong, Q.: Energetic Electron Dynamic in the Inner Radiation Belt and SAA Region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18185, https://doi.org/10.5194/egusphere-egu24-18185, 2024.

EGU24-18633 | Posters on site | ST2.3

Connecting the Geoelectric Field to its Magnetospheric Sources in a Global Hybrid-Vlasov Simulation 

Konstantinos Horaites and the the Vlasiator Team

Field-aligned currents originating in Earth's magnetosphere can flow down to the ionosphere, where they spread out horizontally in order to close the circuit. These currents produce a fluctuating magnetic field, which in turn induces the ground geoelectric field. We study this system using the 3D global hybrid-Vlasov code Vlasiator, which has recently been extended to model ionospheric physics. This approach allows a straightforward analysis of how induced fields on Earth's surface are connected to their magnetospheric drivers. In particular, we consider how fluctuations near Earth's magnetopause can ultimately give rise to a dayside geoelectric field. Possible driving mechanisms considered include flux transfer events and magnetopause surface waves.

How to cite: Horaites, K. and the the Vlasiator Team: Connecting the Geoelectric Field to its Magnetospheric Sources in a Global Hybrid-Vlasov Simulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18633, https://doi.org/10.5194/egusphere-egu24-18633, 2024.

A long-standing question in studying the plasma dynamics in the magnetosphere pertains to the mass coupling between the ionosphere and the global magnetosphere. This presentation explores the connection between different plasma populations lying within and outside the magnetosphere, and employs an integrated computational approach to model the geospace environment, enabling a comprehensive analysis of the evolution of all significant heavy ion species. 

In this presentation, we explore the circulation patterns, transport, and energization of heavy ions as they are transported from the high-latitude ionosphere across the expansive magnetosphere, examining their influence on the dynamics of the inner magnetospheric plasma. Moreover, we present compelling evidence indicating that the presence of energetic heavy ions in the inner magnetosphere significantly contributes to the initial stages of plasmasphere refilling. This contribution stems from the composition of heavy ions within the plasma sheet, which primarily dictates the formation of cold protons through charge exchange with the geocorona, with the neutral density exerting a comparatively minor role. 

How to cite: Ilie, R. and Liu, J.: How the ionosphere is shaping the dynamics of the near-Earth plasma: Insights into mass coupling across the magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20829, https://doi.org/10.5194/egusphere-egu24-20829, 2024.

EGU24-3260 | Orals | ST2.5

Complex dayside particle precipitation observed during the passage of solar wind discontinuities   

Jean Berchem, Simon Wing, and C. Philippe Escoubet

Most studies of the geoeffectiveness of the solar wind tend to focus on coronal mass ejections (CMEs) and Corotating Interactive Regions (CIRs). By comparison, fewer studies focus on the geoeffectiveness of the solar wind directional discontinuities (DD), either tangential discontinuity (TD) or rotational discontinuity (RD).  We present two examples of solar wind DD interaction with the magnetosphere that lead to complex dayside particle precipitation structures even though the geomagnetic activities remain quiet in those two events.  In the first example, the DD leads to the formations of unusual boundary layer, overlapping mantle, and double cusp as observed by the DMSP spacecraft. The double cusp signature is consistent with simultaneous magnetic reconnection occurring at both low and high latitudes due to the dominant IMF By as confirmed in a global MHD simulation for the event. The existence of a high-latitude reconnection in this even is also supported by Cluster C2, which observes velocity fluctuations and reversals with peak-to-peak amplitudes >800 km s–1 as C2 crosses the magnetopause.  Guided by the MHD simulation, the Cluster observation can be interpreted as the spacecraft crossing reconnection outflows while moving from one side of the X-line to the other.  In the second example, the DD leads to the unusual particle precipitation structure where three distinct ion populations can be found on the same magnetic field line.  These three populations have energies of a few hundreds eVs, a few keVs, and a few tens of keVs, suggesting that ions originating from the magnetosphere, solar wind, and ionosphere, respectively, can coexist on the same field line unthermalized.  Moreover, this unusual particle precipitation region has a spatio-temporal scale of about 1 min or 500 km in the ionosphere.

How to cite: Berchem, J., Wing, S., and Escoubet, C. P.: Complex dayside particle precipitation observed during the passage of solar wind discontinuities  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3260, https://doi.org/10.5194/egusphere-egu24-3260, 2024.

EGU24-3612 | ECS | Posters on site | ST2.5

Statistical Analysis of EMIC waves and Particle Fluxes using POES and Van Allen Probes 

Teresa Esman, Alexa Halford, Joshua Pettit, Remya Bhanu, and Sadie Elliot

Electromagnetic ion cyclotron (EMIC) waves are waves generated through cyclotron instability and propagate at frequencies near the ion cyclotron frequency. These waves are frequent during geomagnetic storms and significantly impact the dynamics of particles in the magnetosphere. Wave-particle interaction can lead to the acceleration and scattering of charged particles. Therefore, the presence of these precipitating particles may indicate the presence of EMIC waves. However, other processes are known to also cause precipitation, such as ULF waves. 

By examining in situ data during POES and Van Allen Probe conjunctions, characteristics of the plasmasphere, magnetosphere, particle fluxes, and EMIC waves are investigated. We conduct a statistical analysis of particle flux under varying conditional limitations associated with the presence or lack of EMIC waves and geomagnetic storms. We use the two sample Kolmogorov-Smirnov test to check multiple null hypotheses and aim to answer increasingly more complex questions as we test our methods and follow assumptions. 

Preliminary results showed a statistical difference between the particle flux observed when there are EMIC waves and when there are no EMIC waves during storm times. We discuss new results, possible implications, and next steps.

How to cite: Esman, T., Halford, A., Pettit, J., Bhanu, R., and Elliot, S.: Statistical Analysis of EMIC waves and Particle Fluxes using POES and Van Allen Probes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3612, https://doi.org/10.5194/egusphere-egu24-3612, 2024.

Based on the multi-scale statistical observations from antarctic Zhongshan station, a rippling aurora-like optical phenomena was observed near the poleward boundary of the aurora. The lack of red emission and extremely small scale indicated the aurora ripple is not likely been the result of the electron or ion perception along the magnetic field line. Through the statistical results of appearance location, fine scale structures and the consistence to the theoretical predication, the Aurora ripple is believed to be mainly caused by the plasma gradient drift instability around aurora. Dreyer et al described this phenomena as Fragmented aurora-like emissions in 2019, considering the patterns of emergence and progression associated with this phenomenon, we suggest to name it as "Aurora ripples". This designation is inspired by the visual resemblance of the phenomenon to rippless formed when a paddle moves through a lake, signifying the interaction of auroral plasma with the atmosphere.

How to cite: Li, B.: Aurora ripples - a visual ionospheric emissions when auroral plasma sweeping through atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3868, https://doi.org/10.5194/egusphere-egu24-3868, 2024.

EGU24-4781 | ECS | Orals | ST2.5

Characterizing auroral precipitation and ionospheric conductance with the Dragon King model in MAGE 

Dong Lin, Shanshan Bao, Wenbin Wang, Viacheslav Merkin, Kareem Sorathia, William Lotko, Dedong Wang, Kevin Pham, Qianli Ma, Thomas Sotirelis, Xueling Shi, Adam Michael, Anthony Sciola, Michael Wiltberger, Frank Toffoletto, John Lyon, and Jeffrey Garretson

Auroral precipitation plays an important role in the magnetosphere-ionosphere-thermosphere (MIT) coupling. Various precipitation spectra have been observed and they are driven by different physical mechanisms. In this study, we report the Dragon King model which is used to characterize auroral precipitation and its consequent ionospheric conductance in the Multiscale Atmosphere-Geospace Environment (MAGE) model, a newly developed whole geospace model. Mono-energetic electron precipitation is derived from large-scale field-aligned currents and drift-physics informed loss cone rate, using the linearized Fridman-Lemaire relation. Diffuse electron precipitation is derived with a drift-physics based ring current model, in which electron lifetime due to interactions with chorus and hiss waves is obtained with an empirical table and electron loss rate is informed by drift physics and IGRF magnetic field. Broadband electron precipitation is derived from a statistical relationship between field-aligned Alfvénic Poynting flux and the precipitation energy flux and number flux. The Dragon King model is validated from different perspectives with various observational data, including the statistical pattern during different categories of solar wind driving conditions, and along-trajectory comparison with satellite measurements. The Dragon King model is further used to understand the drivers of different precipitation and their relative importance with MAGE simulations.

How to cite: Lin, D., Bao, S., Wang, W., Merkin, V., Sorathia, K., Lotko, W., Wang, D., Pham, K., Ma, Q., Sotirelis, T., Shi, X., Michael, A., Sciola, A., Wiltberger, M., Toffoletto, F., Lyon, J., and Garretson, J.: Characterizing auroral precipitation and ionospheric conductance with the Dragon King model in MAGE, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4781, https://doi.org/10.5194/egusphere-egu24-4781, 2024.

EGU24-6932 | ECS | Orals | ST2.5

Performance Assessment of CIMI Electron Precipitation During Geomagnetic Storm 

Dibyendu Sur, John C. Dorelli, Mei-Ching Fok, and Natalia Y. Buzulukova

The Comprehensive Inner Magnetosphere-Ionosphere Model (CIMI) is designed by coupling the Comprehensive Ring Current Model (CRCM) and the Radiation Belt Environment (RBE) model (Fok et al., Journal of Geophysical Research: Space Physics, 119, 2014). The model provides electron and ion distribution functions in Earth’s radiation belt, ring current, estimates energies of precipitated electrons and ions in the ionosphere, calculates plasmaspheric density, ionospheric height-integrated Hall and Pedersen conductivities, ionospheric convection potentials. An important feature of CIMI model is calculation of electron precipitation from diffusion-convection equation that accounts both for particle drift in the inner magnetosphere and wave-particle interactions through various plasma waves. In this paper, the performance of the CIMI in terms of precipitating particle energy distribution is evaluated during the geomagnetic disturbed period of May 31 – June 1, 2013 (minimum Dst = -124nT). The performance of CIMI is observed in correspondence with Defense Meteorological Satellite Program (DMSP) satellite observations. Precipitated electrons (30 keV > E > 500eV) from Earth’s plasma sheet go through wave-particle interactions and produce diffuse aurora, that can be simulated with CIMI model. We compare CIMI electron precipitation energy channels for DMSP energy bins and analyze CIMI performance for different energy bins, mean energy and for the total integrated energy flux. In addition, CIMI model has different options for ionospheric conductance model: 1) empirical model of Hardy et al. (Journal of Geophysical Research: Space Physics, 92, 1987) that depends on Kp-index, and 2) Robinson's formulation (Robinson et al., Journal of Geophysical Research: Space Physics, 92, 1987) where ionospheric conductance depends on electron precipitation mean energy and total energy flux. We study CIMI model performance for two different models of ionospheric conductance and evaluate the feedback of electron precipitation on the ring current and ionospheric electric field.

How to cite: Sur, D., Dorelli, J. C., Fok, M.-C., and Buzulukova, N. Y.: Performance Assessment of CIMI Electron Precipitation During Geomagnetic Storm, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6932, https://doi.org/10.5194/egusphere-egu24-6932, 2024.

EGU24-7379 | Posters on site | ST2.5

Role of the mirror force on the collision rate due to relativistic electron precipitation 

Yuto Katoh, Paul Rosendahl, Yasunobu Ogawa, Yasutaka Hiraki, and Hiroyasu Tadokoro

We numerically evaluate the role of the mirror force on the collision rate due to the relativistic electron precipitation into the ionosphere. We compute the motion of individual precipitating electrons with the mirror force, considering collisions with neutral gas by the Monte Carlo method. We examine the effect of the mirror force on the altitude profile of the ionization rate by comparing the results with those without the mirror force. Simulation results demonstrate that larger kinetic energy lowers the altitude profiles of the collision rate, which is consistent with previous studies. The simulation results also show that the upward motion of electrons bounced back from their mirror points results in the upward broadening of the altitude profile of the collision rate. Electrons with kinetic energies above 100 keV form a secondary peak of the collision rate near the mirror point. The formation of the secondary peak can be explained by the stagnation of electrons around the mirror point because the relatively long duration of staying in neutral gas increases the number of collisions. Simulation results show that under the precipitation of electrons in the kinetic energy range larger than tens of keV with the pitch angle close to the loss cone, the maximum collision rate in the altitude range lower than 100 km becomes one order of the magnitude smaller. The results of the present study suggest the importance of the mirror force for the precise modeling of ionospheric response due to the energetic electron precipitation caused by the pitch angle scattering through wave-particle interactions.

How to cite: Katoh, Y., Rosendahl, P., Ogawa, Y., Hiraki, Y., and Tadokoro, H.: Role of the mirror force on the collision rate due to relativistic electron precipitation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7379, https://doi.org/10.5194/egusphere-egu24-7379, 2024.

EGU24-8654 | ECS | Posters on site | ST2.5 | Highlight

Satellite observations of energetic electron precipitation effect on the polar vortex 

Antti Salminen, Timo Asikainen, and Kalevi Mursula

Wintertime stratosphere and mesosphere are dominated by the polar vortex, a strong westerly wind system surrounding the pole. Polar vortex is variable and can even temporarily collapse during the winter, especially in the northern hemisphere. Several studies have shown that energetic electron precipitation (EEP) strengthens the northern polar vortex. Precipitating electrons come from the near-Earth space, the magnetosphere, and precipitate to the high-latitude thermosphere and mesosphere. There EEP forms odd nitrogen and hydrogen oxides (NOX and HOX) which destroy ozone and affect the temperature in the middle atmosphere. Most studies of the EEP effect on polar vortex have used reanalysis datasets which are based  on both observations and models. However, most reanalysis datasets are limited to stratospheric heights. We study here the EEP effect on the polar vortex and the modulation of this effect by planetary waves in the stratosphere and mesosphere with satellite measurements of EEP (POES/MEPED) and atmospheric properties (Aura/MLS). We derive the Eliassen-Palm flux, a measure for planetary wave activity, and the zonal wind from geopotential height observations. We show that EEP strengthens the stratospheric polar vortex, as found in earlier studies based on reanalysis data, but weakens the mesospheric polar vortex in the northern hemisphere. We also show that the EEP effect on polar vortex depends on the latitudinal distribution of planetary waves in the stratosphere and mesosphere.

How to cite: Salminen, A., Asikainen, T., and Mursula, K.: Satellite observations of energetic electron precipitation effect on the polar vortex, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8654, https://doi.org/10.5194/egusphere-egu24-8654, 2024.

EGU24-8910 | Orals | ST2.5 | Highlight

Global impacts of an extreme Solar Particle Event under different geomagnetic field strengths 

Pavle Arsenovic, Eugene Rozanov, Ilya Usoskin, Chris Turney, Timofei Sukhodolov, Ken McCracken, Marina Friedel, Julien Anet, Stana Simic, Ville Maliniemi, Tatiana Egorova, Monika Korte, Harald Rieder, Alan Cooper, and Thomas Peter

Solar particle events (SPEs) are short-lived bursts of high-energy particles from the solar atmosphere and are widely recognized as posing significant economic risks to modern society. Most SPEs are relatively weak and have minor impacts on the Earth’s environment but historic records contain much stronger SPEs which have the potential to alter atmospheric chemistry, impacting climate and biological life. The impacts of such strong SPEs would be far more severe when the Earth’s protective geomagnetic field weakened, such as during past geomagnetic excursions or reversals. Here we model the impacts of an extreme SPE under different geomagnetic field strengths, focusing on changes in atmospheric chemistry and surface radiation using the atmosphere-ocean-chemistry-climate model SOCOL3-MPIOM and the radiation transfer model LibRadtran. Under current geomagnetic conditions, an extreme SPE would increase NOx concentrations in the polar stratosphere and mesosphere, causing reductions in extratropical stratospheric ozone lasting for about a year. In contrast, with no geomagnetic field there would be a substantial increase in NOx throughout the entire atmosphere, resulting in severe stratospheric ozone depletion for several years. The resulting ground-level UV radiation would remain elevated for up to six years, leading to increases in UV index up to 20-25% and solar-induced DNA damage rates by 40-50%. The potential evolutionary impacts of past extreme SPEs remains an important question, while the risks they pose to human health in modern conditions continue to be underestimated.

How to cite: Arsenovic, P., Rozanov, E., Usoskin, I., Turney, C., Sukhodolov, T., McCracken, K., Friedel, M., Anet, J., Simic, S., Maliniemi, V., Egorova, T., Korte, M., Rieder, H., Cooper, A., and Peter, T.: Global impacts of an extreme Solar Particle Event under different geomagnetic field strengths, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8910, https://doi.org/10.5194/egusphere-egu24-8910, 2024.

EGU24-9212 | ECS | Posters on site | ST2.5

Lightning-induced electron precipitation: Statistical analysis of DEMETER satellite data and WWLLN lightning locations 

Václav Linzmayer, František Němec, Ondřej Santolík, and Ivana Kolmašová

We experimentally analyze the importance of lightning-generated whistlers for electron precipitation from the Van Allen radiation belts. For this purpose, we use the wave and energetic particle data measured by the low-altitude DEMETER spacecraft between 2006 and 2010, complemented by the lightning locations and times obtained by the World Wide Lightning Location Network (WWLLN). We focus on the region above the United States (L-shells between 2 and 3, geomagnetic longitudes between 300 and 360 degrees). This region exhibits a significant difference in the number of lightning between the local summer and winter, allowing us to contrast the two seasons. Additionally, it is located westward of the South Atlantic Anomaly, i.e., the drift loss cone has not yet been emptied, and there are many particles with pitch angles not too far from the bounce loss cone. We show that during the northern summer, when the number of lightning in the region increases tremendously, there is a considerable increase in both the VLF wave intensity and the precipitating energetic electron flux. We perform a correlation analysis to determine the most affected energy range. It also reveals that the effect is more pronounced during the night than during the day, in agreement with the lower wave attenuation in the ionosphere, and it is more pronounced during periods of low geomagnetic activity compared to those of high geomagnetic activity.

How to cite: Linzmayer, V., Němec, F., Santolík, O., and Kolmašová, I.: Lightning-induced electron precipitation: Statistical analysis of DEMETER satellite data and WWLLN lightning locations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9212, https://doi.org/10.5194/egusphere-egu24-9212, 2024.

Reconstructions of energetic electron precipitation (EEP) and the atmospheric ionization it produces are important for state-of-the-art chemistry-climate models, which aim to model the climate impacts of EEP. The current version of the Coupled Model Inter-comparison Project, CMIP6, includes a reconstruction of EEP-induced ionization based on a parameterization dependent on geomagnetic Ap index. This reconstruction has been used in several climate studies over the past years. However, recent investigations have shown that the CMIP6 reconstruction underestimates the level of precipitation. Therefore, the atmospheric/climate impacts of EEP might be underestimated as well.

To address this issue we introduce here a new reconstruction of EEP and the ionization it produces. This reconstruction is based on a new composite of energetic electron measurements from POES satellites which have been corrected for various instrumental and sampling effects. A theoretically motivated form of a pitch angle distribution consistent with pitch angle diffusion is fitted to these data to obtain a more realistic estimate of electron precipitation into the atmosphere.

For the reconstruction we developed a deep learning network, which ingests geomagnetic aa and Dxt indices, sunspot number as well as seasonal variations and solar cycle phase. The network gives as output the daily latitude distributions of precipitating electron fluxes in three energy channels, which is then used to calculate the precipitating electron energy spectrum and associated atmospheric ionization from year 1844 to present.

Here we present the main aspects of this new reconstruction and also compare it with the earlier CMIP6 reconstruction.

How to cite: Asikainen, T. and Putaala, H.-R.: New reconstruction of energetic electron precipitation and atmospheric ionization for 1844-2023 using deep learning networks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11743, https://doi.org/10.5194/egusphere-egu24-11743, 2024.

EGU24-11783 | ECS | Posters on site | ST2.5

Exploring solar wind drivers of omega bands 

Vivian Cribb, Tuija Pulkkinen, Bea Gallardo-Lacourt, Larry Kepko, Mackenzie Ratzlaff, and Eric Donovan

Omega bands are mesoscale auroral structures that emerge as eastward moving sinusoidal undulations of the poleward boundary of the equatorward oval in the post-midnight sector. They have been observed during the recovery phase of substorms and storms, and during periods of steady magnetospheric convection, but to date the statistical occurrence characteristics are unknown.

While omega bands can be seen during stormtime events, their drivers and the magnetospheric conditions in which they appear are not well understood. Gaining insight into the geomagnetic conditions and solar wind drivers that give rise to omega bands could greatly benefit theoretical and simulation studies, ultimately enhancing our understanding of global magnetospheric dynamics.  In this work, we perform a superposed epoch analysis of geomagnetic and solar wind parameters for omega band events identified using THEMIS ASI from 2006 to 2013. We use data from OMNI and SuperMAG to quantify the solar wind-magnetosphere-ionosphere system during these intervals. Since omega bands are known to have a near-Earth source, we hope to use this analysis to better understand their associated current systems and coupling mechanisms between the inner magnetosphere and ionosphere.

How to cite: Cribb, V., Pulkkinen, T., Gallardo-Lacourt, B., Kepko, L., Ratzlaff, M., and Donovan, E.: Exploring solar wind drivers of omega bands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11783, https://doi.org/10.5194/egusphere-egu24-11783, 2024.

EGU24-12099 | Posters on site | ST2.5

Chapman conference: Particle Precipitation: Drivers, Properties, and Impacts on Atmosphere, Ionosphere, Magnetosphere (AIM) Coupling – Feb 2025 at RMIT in Melbourne, AU 

Aaron Breneman, Alexa Halford, Kyle Murphy, Hilde Nesse, Brett Carter, Lauren Blum, Adam Kellerman, Sadie Elliott, and Sam Walton

Energetic particle precipitation (EPP) is one of the fundamental drivers of space weather in the coupled atmosphere-ionosphere-magnetosphere (AIM) system. These electrons and ions from the sun or the terrestrial magnetosphere, ranging in energy from hundreds of eV to GeV, precipitate into the atmosphere in response to enhanced topside (solar and magnetosphere) driving. They deposit their energy at a wide range of altitudes, enhancing ionization, and changing neutral temperature, density, and winds. During times of prolonged driving the resulting changes can adversely affect anthropogenic systems including disruption of communication and power systems, and increased satellite drag leading to orbital decay. In addition to its effects on space weather, EPP has been recognized as an important component of climate via its ability to indirectly destroy ozone, modifying local radiative balance in the middle and upper atmosphere. Despite the recognized importance of EPP to the AIM system, the way in which these two-way coupled systems interact is highly complex and remains poorly understood and constrained. Measurements from our current observational fleet are not able to fully capture EPP-driven AIM dynamics. As a result, we lack a fundamental understanding of many aspects of this coupled system, and models cannot be validated and are inhibited in their ability to forecast space weather. To compound this situation, different aspects of the AIM system are studied by the different communities with insufficient cross-community cooperation. Properly studying AIM dynamics, a societal level priority, requires a global systems science (holistic) approach to data collection, analysis, and modeling. This Chapman conference will bring together participants from the AIM communities to focus efforts on identifying and communicating outstanding issues, how models can bridge knowledge gaps, promising techniques for enhanced analysis, and required new types of observations.

How to cite: Breneman, A., Halford, A., Murphy, K., Nesse, H., Carter, B., Blum, L., Kellerman, A., Elliott, S., and Walton, S.: Chapman conference: Particle Precipitation: Drivers, Properties, and Impacts on Atmosphere, Ionosphere, Magnetosphere (AIM) Coupling – Feb 2025 at RMIT in Melbourne, AU, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12099, https://doi.org/10.5194/egusphere-egu24-12099, 2024.

Energetic particle precipitation into the atmosphere has been identified as a key loss process for electrons in the Earth’s outer radiation belt region. However, direct measurements of the electron flux precipitating into the atmosphere are challenging from high altitude low inclination spacecraft, such as the Van Allen Probes, due to the small angular size of the loss cone along the orbital path of these high-altitude spacecraft. Here we use data from the Polar Orbiting Environmental Satellites (POES)/Space Environment Monitor in low Earth orbit to assess the relationship between the trapped and precipitating electron flux in integral energy channels >30 keV, >100 keV, and >300 keV. Our results highlight that there is a strong non-linear relationship between the flux of trapped and precipitating electrons, with the ratio of precipitating to trapped flux only becoming significantly enhanced once the trapped flux reaches a critical level. This transition from low to high levels of precipitation is consistent with the theory proposed by Kennel and Petschek (K-P) (1966) https://doi.org/10.1029/JZ071i001p00001, whereby intense chorus waves are excited and trigger pitch angle diffusion, resulting in energetic particle precipitation and limiting the trapped flux. Using electron flux data from POES and chorus wave data from the Van Allen Probes, we further test the observations against predictions from the K-P theory. A particle tracing model is also utilized to illustrate a direct link between the drift paths of injected electrons, the occurrence of chorus waves and the spatial distribution of strong electron precipitation into the atmosphere at different energies.

How to cite: Ozeke, L., Mann, I., Olifer, L., Chakraborty, S., and Pettit, J.: The Relationship Between Electron Precipitation and the Population of Trapped Electrons in LEO: New Evidence Supporting a Natural Limit to the Flux of Energetic Electrons, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12857, https://doi.org/10.5194/egusphere-egu24-12857, 2024.

EGU24-14915 | ECS | Posters on site | ST2.5

The High-Energy Tail of Energetic Electron Precipitation: Solar Wind Drivers and Geomagnetic Responses 

Josephine Salice, Hilde Nesse, Noora Partamies, Emilia Kilpua, Andrew Kavanagh, Margot Decotte, Eldho Babu, and Christine Smith-Johnsen

Compositional NOx changes caused by energetic electron precipitation (EEP) at a specific altitude and those co-dependent on vertical transport are referred to as the EEP direct and indirect effect, respectively. The direct effect of EEP at lower mesospheric and upper stratospheric altitudes is linked to the high-energy tail of EEP (>300 keV). The relative importance of the two effects on NOx and their subsequent impact on ozone and dynamical changes at these altitudes remains unresolved due to inadequate particle measurements and scarcity of polar mesospheric NOx observations. An accurate parameterization of the high-energy tail of EEP is, therefore, crucial. This study utilizes EEP flux data from MEPED aboard the POES/Metop satellites from 2004 - 2014 to distinguish >30 keV events from >300 keV events. Data from the Northern and Southern Hemispheres (55-70oN/S) are combined in daily flux estimates. Flux peaks above the 90th percentile of the >30 kev flux are identified. The 33% highest and lowest associated responses in the >300 keV fluxes are labeled "E3 events" and "E1 events", respectively, resulting in 55 events of each type. A sub-selection of "overlapping events" is created based on similar >30 keV fluxes responses. Superposed epoch analysis of mesospheric NO density from SOFIE confirms an observable direct impact on lower mesospheric chemistry associated with E3 events. Elevated solar wind speeds persisting in the recovery phase of a deep Dst trough are characteristic of E3 events. A probability assessment identifies specific thresholds in the solar wind-magnetosphere coupling function (epsilon) and the geomagnetic indices Kp*10 and Dst, crucial for determining the occurrence or exclusion of E1 and E3 events. This study provides insight into which parameters are important for accurately modeling the high-energy tail of EEP.

How to cite: Salice, J., Nesse, H., Partamies, N., Kilpua, E., Kavanagh, A., Decotte, M., Babu, E., and Smith-Johnsen, C.: The High-Energy Tail of Energetic Electron Precipitation: Solar Wind Drivers and Geomagnetic Responses, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14915, https://doi.org/10.5194/egusphere-egu24-14915, 2024.

EGU24-15417 | Posters on site | ST2.5

The High-Energy Tail of Energetic Electron Precipitation: Case studies 

Hilde Nesse and Josephine Salice

Precipitating auroral, ring current, and radiation belt electrons will affect the ionization level and composition of the neutral atmosphere. Knowledge gaps remain regarding the frequency, intensity, and the energy spectrum of the Medium Energy Electron (MEE) precipitation (>30 keV). In particular, the understanding and predictive capabilities of the high-energy tail (>300 keV) are in general poor. This study estimates the loss cone electron fluxes from MEPED observations on board the POES/Metop satellites over a full solar cycle 2004-2014 to distinguish >30 keV events from >300 keV events. Data from the Northern and Southern Hemispheres (55-70oN/S) are combined in daily flux estimates. Flux peaks above the 90th percentile of the >30 kev flux are identified. The 33% highest and lowest associated responses in the >300 keV fluxes are labeled "E3 events" and "E1 events", respectively, resulting in 55 events of each type. Based on superposed epoch analysis, it is evident that high geomagnetic activity increases the probability of E3 events. More specifically, elevated solar wind speeds persisting in the recovery phase of a deep Dst trough appear characteristic of E3 events. Here, we test this assessment by examining solar wind parameters and geomagnetic indices for a selection of single events:

  • E1 and E3 events with similar >30 keV flux strengths
  • The E1 event with highest >30 keV flux strength
  • The E3 event with the weakest >30 keV flux strength
  • The E1 event with the strongest Dst deflection
  • The E3 event with the weakest Dst deflection

How to cite: Nesse, H. and Salice, J.: The High-Energy Tail of Energetic Electron Precipitation: Case studies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15417, https://doi.org/10.5194/egusphere-egu24-15417, 2024.

EGU24-15761 | ECS | Orals | ST2.5

Estimation of extreme electron fluxes at geostationary orbit: a statistical and a physical approach 

Mikko Savola, Adnane Osmane, Lucile Turc, Emilia Kilpua, and Minna Palmrooth

The outer Van Allen belt is home to relativistic electrons and experience large variations in electron fluxes during geomagnetic driving events. Many satellite orbits, especially geostationary ones, overlap with the radiation belts and experience high-energy electron radiation. This radiation causes surface and internal charging, accompanied by aging of satellite components. In order to determine the impact on satellites during strong and extreme geomagnetic storms, one needs to quantify the magnitude of the fluxes. In this communication, we compare two different methods for estimating large flux values at geostationary orbit. The first method is physical and relies on the Kennel-Petschek limit (Kennel&Petschek, 1966). The second method is purely statistical and originates in extreme value theory (Coles, 2001). Using extreme value theory (EVT), for electron energies of 130 keV, we find for the once in 150 years electron flux an expected value that is two orders of magnitude larger than electron flux during the Halloween storm of 2003. On the other hand, the Kennel-Petschek limit, for the 130 keV electrons at L=6.7, which corresponds to geostationary orbit, is 1/6 of the maximum of the Halloween storm flux. The EVT therefore provides much larger estimates than the Kennel-Petschek limit. We compare the two methodologies with their respective strengths and limitations and determine under which conditions they should be combined to estimate extreme fluxes in the radiation belts. 

How to cite: Savola, M., Osmane, A., Turc, L., Kilpua, E., and Palmrooth, M.: Estimation of extreme electron fluxes at geostationary orbit: a statistical and a physical approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15761, https://doi.org/10.5194/egusphere-egu24-15761, 2024.

EGU24-15929 | Orals | ST2.5 | Highlight

Calculation of photoelectron induced UV emission with application to the SMILE mission 

Robert Rankin, Dmytro Sydorenko, Jun Liang, and Eric Donovan

The SMILE mission, supported by the European Space Agency and the Chinese Academy of Sciences, is scheduled for launch in 2024. The mission is augmented by a substantial ground-based network of optical ASI's. Here, we report  progress in developing a numerical model of UV emissions to aid interpretation of images collected by the SMILE UVI.  The model calculates UV emissions produced by suprathermal electrons, accounting for prominent UV auroral and dayglow emission lines and bands, including OI 130.4/135.6nm, Lyman-Birge-Hopfield (LBH) and Vegard-Kaplan (VK) bands. It also calculates line-of-sight absorption and the integrated UV photon flux spectrum reaching each UVI-imager pixel. Photoelectron energy spectra for the UV emission module are generated using a Monte Carlo model of photoelectron propagation. This model accounts for 52 kinds of electron-neutral collisions as well as Coulomb collisions. Considering closed geomagnetic field lines in the night sector, and depending on Earth's position relative to the Sun, the model predicts the appearance of energetic photoelectrons coming from the day sector. Coulomb scattering prevents pthese hotoelectrons from reaching the opposite ionosphere [c.f., Khazanov et al, 1994]. To reveal the importance of Coulomb collisions, model photoelectron fluxes and related UV emissions were calculated with Coulomb collisions included and omitted for five locations along the orbit of the DMSP F16 satellite on UT0800 January 1, 2017, which observed anomalous UV emission induced by conjugate photoelectrons [Kil et al., 2020]. Omitting Coulomb collisions overestimates the photoelectron flux and the intensity of UV emission by up to 50% with the effect being more pronounced on longer field lines.

Solar EUV photons also produce energetic photoelectrons which ionize neutrals, heat ambient electrons, and cause UV emission. These photoelectrons can penetrate into the nightside even when connected to the day sector by geomagnetic field lines. UV emission caused by such photoelectrons in the night sector is called anomalous UV emission. knowlege of which is important for the analysis of data from the SMILE UVI. The model development for SMILE includes a module that calculates propagation of photoelectrons and related UV emission. Results from the model are benchmarked against observations by the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) of the DMSP F16 spacecraft. The spacecraft was in Earths shadow, and traveling towards the equatorial plane. The observed anomalous UV emission rapidly decreases as the spacecraft approaches lower latitudes where field lines are shorter and almost completely in the shadow. Values of the UV emission at wavelengths of 135.6 nm and 130.4 nm were calculated from the model at several locations along the spacecraft orbit. Calculations performed with a tilted dipole geomagnetic field gave values that were significantly larger than the observed ones. Calculations using the International Reference Geomagnetic Field (IGRF) provided much improved agreement between the model and the observation because the IGRF places the southern ends of geomagnetic field lines farther from the sunlit hemisphere. The improved agreement suggests the model development related to the SMILE mission will aid interpretation of the data.

How to cite: Rankin, R., Sydorenko, D., Liang, J., and Donovan, E.: Calculation of photoelectron induced UV emission with application to the SMILE mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15929, https://doi.org/10.5194/egusphere-egu24-15929, 2024.

EGU24-24 | Orals | NP4.1

The fractional Sinusoidal wavefront Model (fSwp) for time series displaying persistent stationary cycles 

Gael Kermarrec, Federico Maddanu, Anna Klos, and Tommaso Proietti

In the analysis of sub-annual climatological or geodetic time series such as tide gauges, precipitable water vapor, or GNSS vertical displacements time series but also temperatures or gases concentrations, seasonal cycles are often found to have a time-varying amplitude and phase.

These time series are usually modelled with a deterministic approach that includes trend, annual, and semi-annual periodic components having constant amplitude and phase-lag. This approach can potentially lead to inadequate interpretations, such as an overestimation of Global Navigation Satellite System (GNSS) station velocity, up to masking important geophysical phenomena that are related to the amplitude variability and are important for deriving trustworthy interpretation for climate change assessment.

We address that challenge by proposing a novel linear additive model called the fractional Sinusoidal Waveform process (fSWp), accounting for possible nonstationary cyclical long memory, a stochastic trend that can evolve over time and an additional serially correlated noise capturing the short-term variability. The model has a state space representation and makes use of the Kalman filter (KF). Suitable enhancements of the basic methodology enable handling data gaps, outliers, and offsets. We demonstrate our method using various climatological and geodetic time series to illustrate its potential to capture the time-varying stochastic seasonal signals.

How to cite: Kermarrec, G., Maddanu, F., Klos, A., and Proietti, T.: The fractional Sinusoidal wavefront Model (fSwp) for time series displaying persistent stationary cycles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-24, https://doi.org/10.5194/egusphere-egu24-24, 2024.

On some maps of the first military survey of the Habsburg Empire, the upper direction of the sections does not face the cartographic north, but makes an angle of about 15° with it. This may be due to the fact that the sections were subsequently rotated to the magnetic north of the time. Basically, neither their projection nor their projection origin is known yet.

In my research, I am dealing with maps of Inner Austria, the Principality of Transylvania and Galicia (nowadays Poland and Ukraine), and I am trying to determine their projection origin. For this purpose, it is assumed, based on the archival documentation of the survey, that these are Cassini projection maps. My hypothesis is that they are Graz, Cluj Napoca or Alba Julia and Lviv. I also consider the position of Vienna in each case, since it was the main centre of the survey.

The angle of rotation was taken in part from the gufm1 historical magnetic model back to 1590 for the assumed starting points and year of mapping. In addition, as a theoretical case, I calculated the rotation angle of the map sections using coordinate geometry. I then calculated the longitude of the projection starting point for each case using univariate minimization. Since the method is invariant to latitude, it can only be determined from archival data.

Based on these, the starting point for Inner Austria from the rotation of the map was Vienna, which is not excluded by the archival sources, and since the baseline through Graz also started from there, it is partly logical. The map rotation for Galicia and Transylvania also confirmed the starting point of the hypothesis.  Since both Alba Julia and Cluj Napoca lie at about the same longitude, the method cannot make a difference there; and the archival data did not provide enough evidence. In comparison, the magnetic declination rotations yielded differences of about 1°, which may be due to an error in the magnetic model.

On this basis, I have given the assumed projections of the three maps with projection starting points, and developed a method for determining the projection starting points of the other rotated grid maps. The results suggest that there is a very high probability that the section network was rotated in the magnetic north direction, and thus provide a way to refine the magnetic declination data at that time.

With this method I managed to give new indirekt magnetic declinations data from Central-East Europe, which can help to improve the historical magnetic field models. The main reason for this is that we don’t have any measurement from that region.

Furthermore the difference beetwen the angle of the section north and the declination data from gufm1 always 0.8-1°. Maybe there are systematical data error at that region.

Supported by the ÚNKP-23-6 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund.

How to cite: Koszta, B. and Timár, G.: A possible cartographical data source for historical magnetic field improvement: The direction of the section north of the Habsburg first military survey, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-582, https://doi.org/10.5194/egusphere-egu24-582, 2024.

EGU24-1988 | ECS | Posters on site | NP4.1

Predictive ability assessment of Bayesian Causal Reasoning (BCR) on runoff temporal series 

Santiago Zazo, José Luis Molina, Carmen Patino-Alonso, and Fernando Espejo

The alteration of traditional hydrological patterns due to global warming is leading to a modification of the hydrological cycle. This situation draws a complex scenario for the sustainable management of water resources. However, this issue offers a challenge for the development of innovative approaches that allow an in-depth capturing the logical temporal-dependence structure of these modifications to advance sustainable management of water resources, mainly through the reliable predictive models. In this context, Bayesian Causality (BC), addressed through Causal Reasoning (CR) and supported by a Bayesian Networks (BNs), called Bayesian Causal Reasoning (BCR) is a novel hydrological research area that can help identify those temporal interactions efficiently.

This contribution aims to assesses the BCR ability to discover the logical and non-trivial temporal-dependence structure of the hydrological series, as well as its predictability. For this, a BN that conceptually synthesizes the time series is defined, and where the conditional probability is propagated over the time throughout the BN through an innovative Dependence Mitigation Graph. This is done by coupling among an autoregressive parametric approach and causal model. The analytical ability of the BCR highlighted the logical temporal structure, latent in the time series, which defines the general behavior of the runoff. This logical structure allowed to quantify, through a dependence matrix which summarizes the strength of the temporal dependencies, the two temporal fractions that compose the runoff: one due to time (Temporally Conditioned Runoff) and one not (Temporally Non-conditioned Runoff). Based on this temporal conditionality, a predictive model is implemented for each temporal fraction, and its reliability is assessed from a double probabilistic and metrological perspective.

This methodological framework is applied to two Spanish unregulated sub-basins; Voltoya river belongs to Duero River Basin, and Mijares river, in the Jucar River Basin. Both cases with a clearly opposite temporal behavior, Voltoya independent and Mijares dependent, and with increasingly more problems associated with droughts.

The findings of this study may have important implications over the knowledge of temporal behavior of water resources of river basin and their adaptation. In addition, TCR and TNCR predictive models would allow advances in the optimal dimensioning of storage infrastructures (reservoirs), with relevant substantial economic/environmental savings. Also, a more sustainable management of river basins through more reliable control reservoirs’ operation is expected to be achieved. Finally, these results open new possibilities for developing predictive hydrological models within a BCR framework.

How to cite: Zazo, S., Molina, J. L., Patino-Alonso, C., and Espejo, F.: Predictive ability assessment of Bayesian Causal Reasoning (BCR) on runoff temporal series, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1988, https://doi.org/10.5194/egusphere-egu24-1988, 2024.

EGU24-3857 | ECS | Posters on site | NP4.1 | Highlight

Spatial-Temporal Analysis of Forest Mortality 

Sara Alibakhshi

Climate-induced forest mortality poses an increasing threat worldwide, which calls for developing robust approaches to generate early warning signals of upcoming forest state change. This research explores the potential of satellite imagery, utilizing advanced spatio-temporal indicators and methodologies, to assess the state of forests preceding mortality events. Traditional approaches, such as techniques based on temporal analyses, are impacted by limitations related to window size selection and detrending methods, potentially leading to false alarms. To tackle these challenges, our study introduces two new approaches, namely the Spatial-Temporal Moran (STM) and Spatial-Temporal Geary (STG) approaches, both focusing on local spatial autocorrelation measures. These approaches can effectively address the shortcomings inherent in traditional methods. The research findings were assessed across three study sites within California national parks, and Kendall's tau was employed to quantify the significance of false and positive alarms. To facilitate the measurement of ecosystem state change, trend estimation, and identification of early warning signals, this study also provides "stew" R package. The implications of this research extend to various groups, such as ecologists, conservation practitioners, and policymakers, providing them with the means to address emerging environmental challenges in global forest ecosystems.

How to cite: Alibakhshi, S.: Spatial-Temporal Analysis of Forest Mortality, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3857, https://doi.org/10.5194/egusphere-egu24-3857, 2024.

Iram Parvez1, Massimiliano Cannata2, Giorgio Boni1, Rossella Bovolenta1 ,Eva Riccomagno3 , Bianca Federici1

1 Department of Civil, Chemical and Environmental Engineering (DICCA), Università degli Studi di Genova, Via Montallegro 1, 16145 Genoa, Italy (iram.parvez@edu.unige.it,bianca.federici@unige.it, giorgio.boni@unige.it, rossella.bovolenta@unige.it).

2 Institute of Earth Sciences (IST), Department for Environment Constructions and Design (DACD), University of Applied Sciences and Arts of Southern Switzerland (SUPSI), CH-6952 Canobbio, Switzerland(massimiliano.cannata@supsi.ch).

3 Department of Mathematics, Università degli Studi di Genova, Via Dodecaneso 35, 16146 Genova, Italy(riccomag@dima.unige.it).

The deployment of hydrometeorological sensors significantly contributes to generating real-time big data. The quality and reliability of large datasets pose considerable challenges, as flawed analyses and decision-making processes can result. This research aims to address the issue of anomaly detection in real-time data by exploring machine learning models. Time-series data is collected from IstSOS - Sensor Observation Service, an open-source software that stores, collects and disseminates sensor data. The methodology consists of Gated Recurrent Units based on recurrent neural networks, along with corresponding prediction intervals, applied both to individual sensors and collectively across all temperature sensors within the Ticino region of Switzerland. Additionally, non-parametric methods like Bootstrap and Mean absolute deviation are employed instead of standard prediction intervals to tackle the non-normality of the data. The results indicate that Gated Recurrent Units based on recurrent neural networks, coupled with non-parametric forecast intervals, perform well in identifying erroneous data points. The application of the model on multivariate time series-sensor data establishes a pattern or baseline of normal behavior for the area (Ticino). When a new sensor is installed in the same region, the recognized pattern is used as a reference to identify outliers in the data gathered from the new sensor.

How to cite: Parvez, I.: Exploring Machine Learning Models to Detect Outliers in HydroMet Sensors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4280, https://doi.org/10.5194/egusphere-egu24-4280, 2024.

EGU24-5268 | ECS | Orals | NP4.1

Unveiling Geological Patterns: Bayesian Exploration of Zircon-Derived Time Series Data 

Hang Qian, Meng Tian, and Nan Zhang

For its immunity to post-formation geological modifications, zircon is widely utilized as chronological time capsule and provides critical time series data potential to unravel key events in Earth’s geological history, such as supercontinent cycles. Fourier analysis, which assumes stationary periodicity, has been applied to zircon-derived time series data to find the cyclicity of supercontinents, and wavelet analysis, which assumes non-stationary periodicity, corroborates the results of Fourier Analysis in addition to detecting finer-scale signals. Nonetheless, both methods still prognostically assume periodicity in the zircon-derived time-domain data. To stay away from the periodicity assumption and extract more objective information from zircon data, we opt for a Bayesian approach and treat zircon preservation as a composite stochastic process where the number of preserved zircon grains per magmatic event obeys logarithmic series distribution and the number of magmatic events during a geological time interval obeys Poisson distribution. An analytical solution was found to allow us to efficiently invert for the number and distribution(s) of changepoints hidden in the globally compiled zircon data, as well as for the zircon preservation potential (encoded as a model parameter) between two neighboring changepoints. If the distributions of changepoints temporally overlap with those of known supercontinents, then our results serve as an independent, mathematically robust test of the cyclicity of supercontinents. Moreover, our statistical approach inherently provides a sensitivity parameter the tuning of which allows to probe changepoints at various temporal resolution. The constructed Bayesian framework is thus of significant potential to detect other types of trend swings in Earth’s history, such as shift of geodynamic regimes, moving beyond cyclicity detection which limits the application of conventional Fourier/Wavelet analysis.

How to cite: Qian, H., Tian, M., and Zhang, N.: Unveiling Geological Patterns: Bayesian Exploration of Zircon-Derived Time Series Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5268, https://doi.org/10.5194/egusphere-egu24-5268, 2024.

Semi-enclosed freshwater and brackish ecosystems, characterised by restricted water outflow and prolonged residence times, often accumulate nutrients, influencing their productivity and ecological dynamics. These ecosystems exhibit significant variations in bio-physical-chemical attributes, ecological importance, and susceptibility to human impacts. Untangling the complexities of their interactions remains challenging, necessitating a deeper understanding of effective management strategies adapted to their vulnerabilities. This research focuses on the bio-physical aspects, investigating the differential effects of spring and summer light on phytoplankton communities in semi-enclosed freshwater and brackish aquatic ecosystems.

Through extensive field sampling and comprehensive environmental parameter analysis, we explore how phytoplankton respond to varying light conditions in these distinct environments. Sampling campaigns were conducted at Müggelsee, a freshwater lake on Berlin's eastern edge, and Barther Bodden, a coastal lagoon northeast of Rostock on the German Baltic Sea coast, during the springs and summers of 2022 and 2023, respectively. Our analysis integrates environmental factors such as surface light intensity, diffuse attenuation coefficients, nutrient availability, water column dynamics, meteorological data, Chlorophyll-a concentration, and phytoplankton communities. Sampling encompassed multiple depths at continuous intervals lasting three days.

Preliminary findings underscore significant differences in seasonal light availability, with summer exhibiting extended periods of substantial light penetration. These variations seem to impact phytoplankton abundance and diversity uniquely in each ecosystem. While ongoing analyses are underway, early indications suggest distinct phytoplankton responses in terms of species composition and community structure, influenced by the changing light levels. In 2022 the clear water phase during spring indicated that bloom events have occurred under ice cover much earlier than spring, while in the summer there were weak and short-lived blooms of cyanobacteria. The relationship between nutrient availability and phytoplankton dynamics, however, remains uncertain according to our data.

This ongoing study contributes to understanding the role of light as a primary driver shaping phytoplankton community structures and dynamics in these environments.  Our research findings offer insights for refining predictive models, aiding in ecosystem-specific eutrophication management strategies, and supporting monitoring efforts of Harmful Algal Blooms.

How to cite: Kaharuddin, A. and Kaligatla, R.: Comparative Study of Spring and Summer Light Effects on Phytoplankton Communities in Semi-Enclosed Fresh- and Brackish Aquatic Ecosystems., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5733, https://doi.org/10.5194/egusphere-egu24-5733, 2024.

EGU24-6065 | ECS | Orals | NP4.1

Magnetospheric time history:  How much do we need for forecasting? 

Kendra R. Gilmore, Sarah N. Bentley, and Andy W. Smith

Forecasting the aurora and its location accurately is important to mitigate any potential harm to vital infrastructure like communications and electricity grid networks. Current auroral prediction models rely on our understanding of the interaction between the magnetosphere and the solar wind or geomagnetic indices. Both approaches do well in predicting but have limitations concerning forecasting (geomagnetic indices-based model) or because of the underlying assumptions driving the model (due to a simplification of the complex interaction). By applying machine learning algorithms to this problem, gaps in our understanding can be identified, investigated, and closed. Finding the important time scales for driving empirical models provides the necessary basis for our long-term goal of predicting the aurora using machine learning.

Periodicities of the Earth’s magnetic field have been extensively studied on a global scale or in regional case studies. Using a suite of different time series analysis techniques including frequency analysis and investigation of long-scale changes of the median/ mean, we examine the dominant periodicities of ground magnetic field measurements at selected locations. A selected number of stations from the SuperMAG network (Gjerloev, 2012), which is a global network of magnetometer stations across the world, are the focus of this investigation.

The periodicities retrieved from the different magnetic field components are compared to each other as well as to other locations. In the context of auroral predictions, an analysis of the dominating periodicities in the auroral boundary data derived from the IMAGE satellite (Chisham et al., 2022) provides a counterpart to the magnetic field periodicities.

Ultimately, we can constrain the length of time history sensible for forecasting.

How to cite: Gilmore, K. R., Bentley, S. N., and Smith, A. W.: Magnetospheric time history:  How much do we need for forecasting?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6065, https://doi.org/10.5194/egusphere-egu24-6065, 2024.

EGU24-6151 | Posters on site | NP4.1

Using information-theory metrics to detect regime changes in dynamical systems 

Javier Amezcua and Nachiketa Chakraborty

Dynamical systems can display a range of dynamical regimes (e.g. attraction to, fixed points, limit cycles, intermittency, chaotic behaviour) depending on the values of parameters in the system. In this work we demonstrate how non-parametric entropy estimation codes (in particular NPEET) based on the Kraskov method can be applied to find regime transitions in a 3D chaotic model (the Lorenz 1963 system) when varying the values of the parameters. These infromation-theory-based methods are simpler and cheaper to apply than more traditional metrics from dynamical systems (e.g. computation of Lyapunov exponents). The non-parametric nature of the method allows for handling long time series without a prohibitive computational burden. 

How to cite: Amezcua, J. and Chakraborty, N.: Using information-theory metrics to detect regime changes in dynamical systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6151, https://doi.org/10.5194/egusphere-egu24-6151, 2024.

EGU24-9367 | ECS | Orals | NP4.1

Fractal complexity evaluation of meteorological droughts over three Indian subdivisions using visibility Graphs 

Susan Mariam Rajesh, Muraleekrishnan Bahuleyan, Arathy Nair GR, and Adarsh Sankaran

Evaluation of scaling properties and fractal formalisms is one of the potential approaches for modelling complex series. Understanding the complexity and fractal characterization of drought index time series is essential for better preparedness against drought disasters. This study presents a novel visibility graph-based evaluation of fractal characterization of droughts of three meteorological subdivisions of India. In this method, the horizontal visibility graph (HVG) and Upside-down visibility graph (UDVG) are used for evaluating the network properties for different standardized precipitation index (SPI) series of 3, 6 and 12 month time scales representing short, medium and long term droughts. The relative magnitude of fractal estimates is controlled by the drought characteristics of wet-dry transitions. The estimates of degree distribution clearly deciphered the self-similar properties of droughts of all the subdivisions. For an insightful depiction of drought dynamics, the fractal exponents and spectrum are evaluated by the concurrent application of Sand Box Method (SBM) and Chhabra and Jenson Method (CJM). The analysis was performed for overall series along with the pre- and post-1976-77 Global climate shift scenarios. The complexity is more evident in short term drought series and UDVG formulations implied higher fractal exponents for different moment orders irrespective of drought type and locations considered in this study. Useful insights on the relationship between complex network and fractality are evolved from the study, which may help in improved drought forecasting. The visibility graph based fractality estimation evaluation is efficient in capturing drought and it has vast potential in the drought predictions in a changing environment.

Keywords:  Drought, Fractal, SPI, Visibility Graph

How to cite: Rajesh, S. M., Bahuleyan, M., Nair GR, A., and Sankaran, A.: Fractal complexity evaluation of meteorological droughts over three Indian subdivisions using visibility Graphs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9367, https://doi.org/10.5194/egusphere-egu24-9367, 2024.

EGU24-9537 | Posters on site | NP4.1

Wavelet-Induced Mode Extraction procedure: Application to climatic data 

Elise Faulx, Xavier Fettweis, Georges Mabille, and Samuel Nicolay

The Wavelet-Induced Mode Extraction procedure (WIME) [2] was developed drawing inspiration from Empirical Mode Decomposition. The concept involves decomposing the signal into modes, each presenting a characteristic frequency, using continuous wavelet transform. This method has yielded intriguing results in climatology [3,4]. However, the initial algorithm did not account for the potential existence of slight frequency fluctuations within a mode, which could impact the reconstruction of the original signal [4]. The new version (https://atoms.scilab.org/toolboxes/toolbox_WIME/0.1.0) now allows for the evolution of a mode in the space-frequency half-plane, thus considering the frequency evolution of a mode [2]. A natural application of this tool is in the analysis of Milankovitch cycles, where subtle changes have been observed throughout history. The method also refines the study of solar activity, highlighting the role of the "Solar Flip-Flop." Additionally, the examination of temperature time series confirms the existence of cycles around 2.5 years. It is now possible to attempt to correlate solar activity with this observed temperature cycle, as seen in speleothem records [1].

[1] Allan, M., Deliège, A., Verheyden, S., Nicolay S. and Fagel, N. Evidence for solar influence in a Holocene speleothem record, Quaternary Science Reviews, 2018.
[2] Deliège, A. and Nicolay, S., Extracting oscillating components from nonstationary time series: A wavelet-induced method, Physical Review. E, 2017.
[3] Nicolay, S., Mabille, G., Fettweis, X. and Erpicum, M., A statistical validation for the cycles found in air temperature data using a Morlet wavelet-based method, Nonlinear Processes in Geophysics, 2010.
[4] Nicolay, S., Mabille, G., Fettweis, X. and Erpicum, M., 30 and 43 months period cycles found in air temperature time series using the Morlet wavelet, Climate Dynamics, 2009.

How to cite: Faulx, E., Fettweis, X., Mabille, G., and Nicolay, S.: Wavelet-Induced Mode Extraction procedure: Application to climatic data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9537, https://doi.org/10.5194/egusphere-egu24-9537, 2024.

EGU24-10258 | Orals | NP4.1

New concepts on quantifying event data 

Norbert Marwan and Tobias Braun

A wide range of geoprocesses manifest as observable events in a variety of contexts, including shifts in palaeoclimate regimes, evolutionary milestones, tectonic activities, and more. Many prominent research questions, such as synchronisation analysis or power spectrum estimation of discrete data, pose considerable challenges to linear tools. We present recent advances using a specific similarity measure for discrete data and the method of recurrence plots for different applications in the field of highly discrete event data. We illustrate their potential for palaeoclimate studies, particularly in detecting synchronisation between signals of discrete extreme events and continuous signals, estimating power spectra of spiky signals, and analysing data with irregular sampling.

How to cite: Marwan, N. and Braun, T.: New concepts on quantifying event data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10258, https://doi.org/10.5194/egusphere-egu24-10258, 2024.

EGU24-10415 | ECS | Orals | NP4.1

Application of Transfer Learning techniques in one day ahead PV production prediction 

Marek Lóderer, Michal Sandanus, Peter Pavlík, and Viera Rozinajová

Nowadays photovoltaic panels are becoming more affordable, efficient, and popular due to their low carbon footprint. PV panels can be installed in many places providing green energy to the local grid reducing energy cost and transmission losses. Since the PV production is highly dependent on the weather conditions, it is extremely important to estimate expected output in advance in order to maintain energy balance in the grid and provide enough time to schedule load distribution. The PV production output can be calculated by various statistical and machine learning prediction methods. In general, the more data available, the more precise predictions can be produced. This poses a problem for recently installed PV panels for which not enough data has been collected or the collected data are incomplete. 

A possible solution to the problem can be the application of an approach called Transfer Learning which has the inherent ability to effectively deal with missing or insufficient amounts of data. Basically, Transfer Learning is a machine learning approach which offers the capability of transferring knowledge acquired from the source domain (in our case a PV panel with a large amount of historical data) to different target domains (PV panels with very little collected historical data) to resolve related problems (provide reliable PV production predictions). 

In our study, we investigate the application, benefits and drawbacks of Transfer Learning for one day ahead PV production prediction. The model used in the study is based on complex neural network architecture, feature engineering and data selection. Moreover, we focus on the exploration of multiple approaches of adjusting weights in the target model retraining process which affect the minimum amount of training data required, final prediction accuracy and model’s overall robustness. Our models use historical meteorological forecasts from Deutscher Wetterdienst (DWD) and photovoltaic measurements from the project PVOutput which collects data from installed solar systems across the globe. Evaluation is performed on more than 100 installed PV panels in Central Europe.

How to cite: Lóderer, M., Sandanus, M., Pavlík, P., and Rozinajová, V.: Application of Transfer Learning techniques in one day ahead PV production prediction, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10415, https://doi.org/10.5194/egusphere-egu24-10415, 2024.

EGU24-11897 | Posters on site | NP4.1

Results of joint processing of magnetic observatory data of international Intermagnet network in a unified coordinate system 

Beibit Zhumabayev, Ivan Vassilyev, Zhasulan Mendakulov, Inna Fedulina, and Vitaliy Kapytin

In each magnetic observatory, the magnetic field is registered in local Cartesian coordinate systems associated with the geographic coordinates of the locations of these observatories. To observe extraterrestrial magnetic field sources, such as the interplanetary magnetic field or magnetic clouds, a method of joint processing of data from magnetic observatories of the international Intermagnet network was implemented. In this method, the constant component is removed from the observation results of individual observatories, their measurement data is converted into the ecliptic coordinate system, and the results obtained from all observatories are averaged after the coordinate transformation.

The first data on joint processing of measurement results from the international network of Intermagnet magnetic observatories in the period before the onset of magnetic storms of various types, during these storms and after their end are presented. There is a significant improvement in the signal-to-noise ratio after combining the measurement results from all observatories, which makes it possible to isolate weaker external magnetic fields. A change in the shape of magnetic field variations is shown, which can provide new knowledge about the mechanism of development of magnetic storms.

How to cite: Zhumabayev, B., Vassilyev, I., Mendakulov, Z., Fedulina, I., and Kapytin, V.: Results of joint processing of magnetic observatory data of international Intermagnet network in a unified coordinate system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11897, https://doi.org/10.5194/egusphere-egu24-11897, 2024.

We introduce the CLEAN algorithm to identify narrowband Ultra Low Frequency (ULF) Pc5 plasma waves in Earth’s magnetosphere. The CLEAN method was first used for constructing 2D images in astronomical radio interferometry but has since been applied to a huge range of areas including adaptation for time series analysis. The algorithm performs a nonlinear deconvolution in the frequency domain (equivalent to a least-squares in the time domain) allowing for identification of multiple individual wave spectral peaks within the same power spectral density. The CLEAN method also produces real amplitudes instead of model fits to the peaks and retains phase information. We applied the method to GOES magnetometer data spanning 30 years to study the distribution of narrowband Pc5 ULF waves at geosynchronous orbit. We found close to 30,0000 wave events in each of the vector magnetic field components in field-aligned coordinates. We discuss wave occurrence and amplitudes distributed in local time and frequency. The distribution of the waves under different solar wind conditions are also presented. With some precautions, which are applicable to other event identification methods, the CLEAN technique can be utilized to detect wave events and its harmonics in the magnetosphere and beyond. We also discuss limitations of the method mainly the detection of unrealistic peaks due to aliasing and Gibbs phenomena.

How to cite: Inceoglu, F. and Loto'aniu, P.: Using the CLEAN Algorithm to Determine the Distribution of Ultra Low Frequency Waves at Geostationary Orbit, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12928, https://doi.org/10.5194/egusphere-egu24-12928, 2024.

EGU24-12938 | Posters on site | NP4.1

Applying Multifractal Theory and Statistical Techniques for High Energy Volcanic Explosion Detection and Seismic Activity Monitoring in Volcanic Time Series 

Marisol Monterrubio-Velasco, Xavier Lana, Raúl Arámbula-Mendoza, and Ramón Zúñiga

Understanding volcanic activity through time series data analysis is crucial for uncovering the fundamental physical mechanisms governing this natural phenomenon.

In this study, we show the application of multifractal and fractal methodologies, along with statistical analysis, to investigate time series associated with volcanic activity. We aim to make use of these approaches to identify significant variations within the physical processes related to changes in volcanic activity. These methodologies offer the potential to identify pertinent changes preceding a high-energy explosion or a significant volcanic eruption.

In particular, we apply it to analyze two study cases. First, the evolution of the multifractal structure of volcanic emissions of low, moderate, and high energy explosions applied to Volcán de Colima (México years 2013-2015). The results contribute to obtaining quite evident signs of the immediacy of possible dangerous emissions of high energy, close to 8.0x10^8 J. Additionally, the evolution of the adapted Gutenberg-Richter seismic law to volcanic energy emissions contributes to confirm the results obtained using multifractal analysis. Secondly, we also studied the time series of the Gutenberg-Richter b-parameter of seismic activities associated with volcanic emissions in Iceland, Hawaii, and the Canary Islands, through the concept of Disparity (degree of irregularity), the fractal Hurst exponent, H, and several multifractal parameters. The results obtained should facilitate a better knowledge of the relationships between the activity of volcanic emissions and the corresponding related seismic activities.  

How to cite: Monterrubio-Velasco, M., Lana, X., Arámbula-Mendoza, R., and Zúñiga, R.: Applying Multifractal Theory and Statistical Techniques for High Energy Volcanic Explosion Detection and Seismic Activity Monitoring in Volcanic Time Series, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12938, https://doi.org/10.5194/egusphere-egu24-12938, 2024.

EGU24-13593 | ECS | Posters on site | NP4.1

Characterizing Uncertainty in Spatially Interpolated Time Series of Near-Surface Air Temperature 

Conor Doherty and Weile Wang

Spatially interpolated meteorological data products are widely used in the geosciences as well as disciplines like epidemiology, economics, and others. Recent work has examined methods for quantifying uncertainty in gridded estimates of near-surface air temperature that produce distributions rather than simply point estimates at each location. However, meteorological variables are correlated not only in space but in time, and sampling without accounting for temporal autocorrelation produces unrealistic time series and potentially underestimates cumulative errors. This work first examines how uncertainty in air temperature estimates varies in time, both seasonally and at shorter timescales. It then uses data-driven, spectral, and statistical methods to better characterize uncertainty in time series of estimated air temperature values. Methods for sampling that reproduce spatial and temporal autocorrelation are presented and evaluated. The results of this work are particularly relevant to domains like agricultural and ecology. Physical processes including evapotranspiration and primary production are sensitive to variables like near-surface air temperature, and errors in these important meteorological inputs accumulate in model outputs over time.

How to cite: Doherty, C. and Wang, W.: Characterizing Uncertainty in Spatially Interpolated Time Series of Near-Surface Air Temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13593, https://doi.org/10.5194/egusphere-egu24-13593, 2024.

EGU24-13879 | ECS | Posters on site | NP4.1

Understanding the role of vegetation responses to drought in regulating autumn senescence 

Eunhye Choi and Josh Gray

Vegetation phenology is the recurring of plant growth, including the cessation and resumption of growth, and plays a significant role in shaping terrestrial water, nutrient, and carbon cycles. Changes in temperature and precipitation have already induced phenological changes around the globe, and these trends are likely to continue or even accelerate. While warming has advanced spring arrival in many places, the effects on autumn phenology are less clear-cut, with evidence for earlier, delayed, or even unchanged end of the growing season (EOS). Meteorological droughts are intensifying in duration and frequency because of climate change. Droughts intricately impact changes in vegetation, contingent upon whether the ecosystem is limited by water or energy. These droughts have the potential to influence EOS changes. Despite this, the influence of drought on EOS remains largely unexplored. This study examined moisture’s role in controlling EOS by understanding the relationship between precipitation anomalies, vegetation’s sensitivity to precipitation (SPPT), and EOS. We also assess regional variations in responses to the impact of SPPT on EOS.

The study utilized multiple vegetation and water satellite products to examine the patterns of SPPT in drought and its impact on EOS across aridity gradients and vegetation types. By collectively evaluating diverse SPPTs from various satellite datasets, this work offers a comprehensive understanding and critical basis for assessing the impact of drought on EOS. We focused on the Northern Hemisphere from 2000 to 2020, employing robust statistical methods. This work found that, in many places, there was a stronger relationship between EOS and drought in areas with higher SPPT. Additionally, a non-linear negative relationship was identified between EOS and SPPT in drier regions, contracting with a non-linear positive relationship observed in wetter regions. These findings were consistent across a range of satellite-derived vegetation products. Our findings provide valuable insights into the effects of SPPT on EOS during drought, enhancing our understanding of vegetation responses to drought and its consequences on EOS and aiding in identifying drought-vulnerable areas.

How to cite: Choi, E. and Gray, J.: Understanding the role of vegetation responses to drought in regulating autumn senescence, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13879, https://doi.org/10.5194/egusphere-egu24-13879, 2024.

EGU24-16981 | ECS | Orals | NP4.1

A machine-learning-based approach for predicting the geomagnetic secular variation 

Sho Sato and Hiroaki Toh

We present a machine-learning-based approach for predicting the geomagnetic main field changes, known as secular variation (SV), in a 5-year range for use for the 14th generation of International Geomagnetic Reference Field (IGRF-14). The training and test datasets of the machine learning (ML) models are geomagnetic field snapshots derived from magnetic observatory hourly means, and CHAMP and Swarm-A satellite data (MCM Model; Ropp et al., 2020). The geomagnetic field data are not used as-is in the original time series but were differenced twice before training. Because SV is strongly influenced by the geodynamo process occurring in the Earth's outer core, challenges still persist despite efforts to model and forecast the realistic nonlinear behaviors (such as the geomagnetic jerks) of the geodynamo through data assimilation. We compare three physics-uninformed ML models, namely, the Autoregressive (AR) model, Vector Autoregressive (VAR) model, and Recurrent Neural Network (RNN) model, to represent the short-term temporal evolution of the geomagnetic main field on the Earth’s surface. The quality of 5-year predictions is tested by the hindcast results for the learning window from 2004.50 to 2014.25. These tests show that the forecast performance of our ML model is comparable with that of candidate models of IGRF-13 in terms of data misfits after the release epoch (Year 2014.75). It is found that all three ML models give 5-year prediction errors of less than 100nT, among which the RNN model shows a slightly better accuracy. They also suggest that Overfitting to the training data used is an undesirable machine learning behavior that occurs when the RNN model gives accurate reproduction of training data but not for forecasting targets.

How to cite: Sato, S. and Toh, H.: A machine-learning-based approach for predicting the geomagnetic secular variation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16981, https://doi.org/10.5194/egusphere-egu24-16981, 2024.

EGU24-17344 | Posters on site | NP4.1

Introducing a new statistical theory to quantify the Gaussianity of the continuous seismic signal 

Éric Beucler, Mickaël Bonnin, and Arthur Cuvier

The quality of the seismic signal recorded at permanent and temporary stations is sometimes degraded, either abruptly or over time. The most likely cause is a high level of humidity, leading to corrosion of the connectors but environmental changes can also alter recording conditions in various frequency ranges and not necessarily for all three components in the same way. Assuming that the continuous seismic signal can be described by a normal distribution, we present a new approach to quantify the seismogram quality and to point out any time sample that deviates from this Gaussian assumption. To this end the notion of background Gaussian signal (BGS) to statistically describe a set of samples that follows a normal distribution. The discrete function obtained by sorting the samples in ascending order of amplitudes is compared to a modified probit function to retrieve the elements composing the BGS, and its statistical properties, mostly the Gaussian standard deviation, which can then differ from the classical standard deviation. Hence the ratio of both standard deviations directly quantifies the dominant gaussianity of the continuous signal and any variation reflects a statistical modification of the signal quality. We present examples showing daily variations in this ratio for stations known to have been affected by humidity, resulting in signal degradation. The theory developed can be used to detect subtle variations in the Gaussianity of the signal, but also to point out any samples that don't match the Gaussianity assumption, which can then be used for other seismological purposes, such as coda determination.

How to cite: Beucler, É., Bonnin, M., and Cuvier, A.: Introducing a new statistical theory to quantify the Gaussianity of the continuous seismic signal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17344, https://doi.org/10.5194/egusphere-egu24-17344, 2024.

EGU24-17566 | ECS | Posters on site | NP4.1

Unveiling Climate-Induced Ocean Wave Activities Using Seismic Array Data in the North Sea Region 

Yichen Zhong, Chen Gu, Michael Fehler, German Prieto, Peng Wu, Zhi Yuan, Zhuoyu Chen, and Borui Kang

Climate events may induce abnormal ocean wave activities, that can be detected by seismic array on nearby coastlines. We collected long-term continuous array seismic data in the Groningen area and the coastal areas of the North Sea, conducted a comprehensive analysis to extract valuable climate information hidden within the ambient noise. Through long-term spectral analysis, we identified the frequency band ranging from approximately 0.2Hz, which appears to be associated with swell waves within the region, exhibiting a strong correlation with the significant wave height (SWH). Additionally, the wind waves with a frequency of approximately 0.4 Hz and gravity waves with periods exceeding 100 seconds were detected from the seismic ambient noise. We performed a correlation analysis between the ambient noise and various climatic indexes across different frequency bands. The results revealed a significant correlation between the North Atlantic Oscillation (NAO) Index and the ambient noise around 0.17Hz.

Subsequently, we extracted the annual variation curves of SWH frequency from ambient noise at each station around the North Sea and assembled them into a sparse spatial grid time series (SGTS). An empirical orthogonal function (EOF) analysis was conducted, and the Principal Component (PC) time series derived from the EOF analysis were subjected to a correlation analysis with the WAVEWATCH III (WW3) model simulation data, thereby confirming the wave patterns. Moreover, we conducted the spatial distribution study of SGTS. The spatial features revealed that the southern regions of the North Sea exhibit higher wind-wave energy components influenced by the Icelandic Low pressure system and topography, which explains the correlation between ambient noise in the region and the NAO index. Furthermore, spatial features disclosed a correlation between the first EOF mode of the North Sea ocean waves and the third mode of sea surface temperature anomalies. This research shows the potential of utilizing existing off-shore seismic monitoring systems to study global climate variation and physical oceanography.

How to cite: Zhong, Y., Gu, C., Fehler, M., Prieto, G., Wu, P., Yuan, Z., Chen, Z., and Kang, B.: Unveiling Climate-Induced Ocean Wave Activities Using Seismic Array Data in the North Sea Region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17566, https://doi.org/10.5194/egusphere-egu24-17566, 2024.

EGU24-18061 | ECS | Orals | NP4.1

A new methodology for time-series reconstruction of global scale historical Earth observation data 

Davide Consoli, Leandro Parente, and Martijn Witjes

Several machine learning algorithms and analytical techniques do not allow gaps or non-values in input data. Unfortunately, earth observation (EO) datasets, such as satellite images, are gravely affected by cloud contamination and sensor artifacts that create gaps in the time series of collected images. This limits the usage of several powerful techniques for modeling and analysis. To overcome these limitations, several works in literature propose different imputation methods to reconstruct the gappy time series of images, providing complete time-space datasets and enabling their usage as input for many techniques.

However, among the time-series reconstruction methods available in literature, only a few of them are publicly available (open source code), applicable without any external source of data, and suitable for application to petabyte (PB) sized dataset like the full Landsat archive. The few methods that match all these characteristics are usually quite trivial (e.g. linear interpolation) and, as a consequence, they often show poor performance in reconstructing the images. 

For this reason, we propose a new methodology for time series reconstruction designed to match all these requirements. Like some other methods in literature, the new method, named seasonally weighted average generalization (SWAG), works purely on the time dimension, reconstructing the images working on each time series of each pixel separately. In particular, the method uses a weighted average of the samples available in the original time series to reconstruct the missing values. Enforcing the annual seasonality of each band as a prior, for the reconstruction of each missing sample in the time series a higher weight is given to images that are collected exactly on integer multiples of a year. To avoid propagation of land cover changes in future or past images, higher weights are given to more recent images. Finally, to have a method that respects causality, only images from the past of each sample in the time series are used.

To have computational performance suitable for PB sized datasets the method has been implemented in C++ using a sequence of fast convolution methods and Hadamard products and divisions. The method has been applied to a bimonthly aggregated version of the global GLAD Landsat ARD-2 collection from 1997 to 2022, producing a 400 terabyte output dataset. The produced dataset will be used to generate maps for several biophysical parameters, such as Fraction of Absorbed Photosynthetically Active Radiation (FAPAR), normalized difference water index (NDWI) and bare soil fraction (BSF). The code is available as open source, and the result is fully reproducible.

References:

Potapov, Hansen, Kommareddy, Kommareddy, Turubanova, Pickens, ... & Ying  (2020). Landsat analysis ready data for global land cover and land cover change mapping. Remote Sensing, 12(3), 426.

Julien, & Sobrino (2019). Optimizing and comparing gap-filling techniques using simulated NDVI time series from remotely sensed global data. International Journal of Applied Earth Observation and Geoinformation, 76, 93-111.

Radeloff, Roy, Wulder, Anderson, Cook, Crawford, ... & Zhu (2024). Need and vision for global medium-resolution Landsat and Sentinel-2 data products. Remote Sensing of Environment, 300, 113918.

How to cite: Consoli, D., Parente, L., and Witjes, M.: A new methodology for time-series reconstruction of global scale historical Earth observation data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18061, https://doi.org/10.5194/egusphere-egu24-18061, 2024.

EGU24-18197 | ECS | Orals | NP4.1 | Highlight

The regularity of climate-related extreme events under global warming 

Karim Zantout, Katja Frieler, and Jacob Schewe and the ISIMIP team

Climate variability gives rise to many different kinds of extreme impact events, including heat waves, crop failures, or wildfires. The frequency and magnitude of such events are changing under global warming. However, it is less known to what extent such events occur with some regularity, and whether this regularity is also changing as a result of climate change. Here, we present a novel method to systematically study the time-autocorrelation of these extreme impact events, that is, whether they occur with a certain regularity. In studies of climate change impacts, different types of events are often studied in isolation, but in reality they interact. We use ensembles of global biophysical impact simulations from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) driven with climate models to assess current conditions and projections. The time series analysis is based on a discrete Fourier transformation that accounts for the stochastic fluctuations from the climate model. Our results show that some climate impacts, such as crop failure, indeed exhibit a dominant frequency of recurrence; and also, that these regularity patterns change over time due to anthropogenic climate forcing.

How to cite: Zantout, K., Frieler, K., and Schewe, J. and the ISIMIP team: The regularity of climate-related extreme events under global warming, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18197, https://doi.org/10.5194/egusphere-egu24-18197, 2024.

EGU24-18210 | ECS | Posters on site | NP4.1

Long-term vegetation development in context of morphodynamic processes since mid-19th century 

Katharina Ramskogler, Moritz Altmann, Sebastian Mikolka-Flöry, and Erich Tasser

The availability of comprehensive aerial photography is limited to the mid-20th century, posing a challenge for quantitatively analyzing long-term surface changes in proglacial areas. This creates a gap of approximately 100 years, spanning the end of the Little Ice Age (LIA). Employing digital monoplotting and historical terrestrial images, our study reveals quantitative surface changes in a LIA lateral moraine section dating back to the second half of the 19th century, encompassing a total study period of 130 years (1890 to 2020). With the long-term analysis at the steep lateral moraines of Gepatschferner (Kauner Valley, Tyrol, Austria) we aimed to identify changes in vegetation development in context with morphodynamic processes and the changing climate.

In 1953, there was an expansion in the area covered by vegetation, notably encompassing scree communities, alpine grassland, and dwarf shrubs. However, the destabilization of the system after 1980, triggered by rising temperatures and the resulting thawing of permafrost, led to a decline in vegetation cover by 2020. Notably, our observations indicated that, in addition to morphodynamic processes, the overarching trends in temperature and precipitation exerted a substantial influence on vegetation development. Furthermore, areas with robust vegetation cover, once stabilised, were reactivated and subjected to erosion, possibly attributed to rising temperatures post-1980.

This study demonstrates the capability of historical terrestrial images to enhance the reconstruction of vegetation development in context with morphodynamics in high alpine environments within the context of climate change. However, it is important to note that long-term mapping of vegetation development through digital monoplotting has limitations, contingent on the accessibility and quality of historical terrestrial images, as well as the challenges posed by shadows in high alpine regions. Despite these limitations, this long-term approach offers fundamental data on vegetation development for future modelling efforts.

How to cite: Ramskogler, K., Altmann, M., Mikolka-Flöry, S., and Tasser, E.: Long-term vegetation development in context of morphodynamic processes since mid-19th century, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18210, https://doi.org/10.5194/egusphere-egu24-18210, 2024.

EGU24-19601 | ECS | Posters on site | NP4.1

Discrimination of  geomagnetic quasi-periodic signals by using SSA Transform 

Palangio Paolo Giovanni and Santarelli Lucia

Discrimination of  geomagnetic quasi-periodic signals by using SSA Transform

  • Palangio1, L. Santarelli 1

1Istituto Nazionale di Geofisica e Vulcanologia L’Aquila

3Istituto Nazionale di Geofisica e Vulcanologia Roma

 

Correspondence to:  lucia.santarelli@ingv.it

 

Abstract

In this paper we present an application of  the SSA Transform to the detection and reconstruction of  very weak geomagnetic signals hidden in noise. In the SSA Transform  multiple subspaces are used for representing and reconstructing   signals and noise.  This analysis allows us to reconstruct, in the time domain, the different harmonic components contained in the original signal by using  ortogonal functions. The objective is to identificate the dominant  subspaces that can be attributed to the  signals and the subspaces that can be attributed to the noise,  assuming that all these  subspaces are orthogonal to each other, which implies that the  signals and noise  are independent of one another. The subspace of the signals is mapped simultaneously on several spaces with a lower dimension, favoring the dimensions that best discriminate the patterns. Each subspace of the signal space is used to encode different subsets of functions having common characteristics, such as  the same periodicities. The subspaces  identification was performed by using singular value decomposition (SVD) techniques,  known as  SVD-based identification methods  classified in a subspace-oriented scheme.The  quasi-periodic variations of geomagnetic field  has been investigated in the range of scale which span from 22 years to 8.9 days such as the  Sun’s polarity reversal cycle (22 years), sun-spot cycle (11 years), equinoctial effect (6 months), synodic rotation of the Sun (27 days) and its harmonics. The strength of these signals vary from fractions of a nT to tens of nT. Phase and frequency variability of these cycles has been evaluated from the range of variations in the geomagnetic field recorded at middle latitude place (covering roughly 4.5 sunspot cycles). Magnetic data recorded at L'Aquila Geomagnetic observatory (geographic coordinates: 42° 23’ N, 13° 19’E, geomagnetic coordinates: 36.3° N,87°.2 E, L-shell=1.6) are used from 1960 to 2009.

 

 

How to cite: Paolo Giovanni, P. and Lucia, S.: Discrimination of  geomagnetic quasi-periodic signals by using SSA Transform, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19601, https://doi.org/10.5194/egusphere-egu24-19601, 2024.

EGU24-22262 | ECS | Posters on site | NP4.1

Temporal Interpolation of Sentinel-2 Multispectral Time Series in Context of Land Cover Classification with Machine Learning Algorithms 

Mate Simon, Mátyás Richter-Cserey, Vivien Pacskó, and Dániel Kristóf

Over the past decades, especially since 2014, large quantities of Earth Observation (EO) data became available in high spatial and temporal resolution, thanks to ever-developing constellations (e.g.: Sentinel, Landsat) and open data policy. However, in the case of optical images, affected by cloud coverage and the spatially changing overlap of relative satellite orbits, creating temporally generalized and dense time series by using only measured data is challenging, especially when studying larger areas.

Several papers investigate the question of spatio-temporal gap filling and show different interpolation methods to calculate missing values corresponding to the measurements. In the past years more products and technologies have been constructed and published in this field, for example Copernicus HR-VPP Seasonal Trajectories (ST) product.  These generalized data structures are essential to the comparative analysis of different time periods or areas and improve the reliability of data analyzing methods such as Fourier transform or correlation. Temporally harmonized input data is also necessary in order to improve the results of Machine Learning classification algorithms such as Random Forest or Convolutional Neural Networks (CNN). These are among the most efficient methods to separate land cover categories like arable lands, forests, grasslands and built-up areas, or crop types within the arable category.

This study analyzes the efficiency of different interpolation methods on Sentinel-2 multispectral time series in the context of land cover classification with Machine Learning. We compare several types of interpolation e.g. linear, cubic and cubic-spline and also examine and optimize more advanced methods like Inverse Distance Weighted (IDW) and Radial Basis Function (RBF). We quantify the accuracy of each method by calculating mean square error between measured and interpolated data points. The role of interpolation of the input dataset in Deep Learning (CNN) is investigated by comparing Overall, Kappa and categorical accuracies of land cover maps created from only measured and interpolated time series. First results show that interpolation has a relevant positive effect on accuracy statistics. This method is also essential in taking a step towards constructing robust pretrained Deep Learning models, transferable between different time intervals and agro-ecological regions.

The research has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the KDP-2021 funding scheme.

 

Keywords: time series analysis, Machine Learning, interpolation, Sentinel

How to cite: Simon, M., Richter-Cserey, M., Pacskó, V., and Kristóf, D.: Temporal Interpolation of Sentinel-2 Multispectral Time Series in Context of Land Cover Classification with Machine Learning Algorithms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22262, https://doi.org/10.5194/egusphere-egu24-22262, 2024.

ST3 – Ionosphere and Thermosphere

The three‐dimensional computerized ionospheric tomography (3DCIT) technique has been used to reconstruct the ionospheric response to the 21 June 2020 annular solar eclipse and the results are evaluated by constellation observing system for meteorology, ionosphere, and climate (COSMIC) observations. The 3DCIT-derived electron density (Ne) difference between the eclipse and quiet days showed that the Ne depletion was between 200-550 km and the maximum magnitude was about -3.0×1011 el/m3 which was at 280 km in altitude. The contributions from below 250 and 350 km altitudes to VTEC (Vertical Total Electron Content) depletion were ~30% and ~60%, respectively. Significant asymmetry of Ne depletion with respect to the eclipse path was captured in 3DCIT results, and the deviation conditions between the Ne depletion central line and eclipse path varied at different altitudes. Simulations with the thermosphere‐ionosphere‐electrodynamics general circulation model (TIEGCM) generally showed consistent ionospheric variations with GNSS (Global Navigation Satellite System) VTEC and 3DCIT electron density. Furthermore, term analysis on the ion continuity equation indicates that the asymmetry of Ne depletion was mainly induced by the neutral wind disturbance which converged toward the eclipse region and caused opposite transport effects on both sides of the eclipse path. The thermospheric composition was also changed by disturbed neutral wind and impacted plasma production and loss rates, contributing to the Ne depletion asymmetry.

How to cite: Zhai, C., Dang, T., Yao, Y., and Kong, J.: Three-Dimensional Ionospheric Evolution and Asymmetry of the Electron Density Depletion Generated by the 21 June 2020 Annular Solar Eclipse, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1554, https://doi.org/10.5194/egusphere-egu24-1554, 2024.

Ionospheric sporadic E layers (Es) are intense plasma irregularities between 80 and 130 km in altitude and are generally unpredictable. Reconstructing the morphology of sporadic E layers is not only essential for understanding the nature of ionospheric irregularities and many other atmospheric coupling systems, but is also useful for solving a broad range of demands for reliable radio communication of many sectors reliant on ionosphere-dependent decision-making. Despite the efforts of many empirical and theoretical models, a predictive algorithm with both high accuracy and high efficiency is still lacking. Here we introduce a new approach for Sporadic E Layer Forecast using Artificial Neural Networks (SELF-ANN). The prediction engine is trained by fusing observational data from multiple sources, including a high-resolution ERA5 reanalysis dataset, Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) radio occultation (RO) measurements, and integrated data from OMNIWeb. The results show that the model can effectively reconstruct the morphology of the ionospheric E layer with intraseasonal variability by learning complex patterns. The model obtains good performance and generalization capability by applying multiple evaluation criteria. The random forest algorithm used for preliminary processing shows that local time, altitude, longitude, and latitude are significantly essential for forecasting the E-layer region. Extensive evaluations based on ground-based observations demonstrate the superior utility of the model in dealing with unknown information. The presented framework will help us better understand the nature of the ionospheric irregularities, which is a fundamental challenge in upper-atmospheric and ionospheric physics. Moreover, the proposed SELF-ANN can make a significant contribution to the development of the prediction of ionospheric irregularities in the E layer, particularly when the formation mechanisms and evolution processes of the Es layer are not well understood.

How to cite: Tian, P.: Ionospheric irregularity reconstruction using multisource data fusion via deep learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3145, https://doi.org/10.5194/egusphere-egu24-3145, 2024.

EGU24-3725 | Orals | ST3.1

HIWIND Balloon and Antarctica Jang Bogo FPI High Latitude Conjugate Thermospheric Wind Observations and Simulations 

Qian Wu, Dong Lin, Wenbin Wang, Liying Qian, Geohwa Jee, Changsup Lee, and Jeong-han Kim

Using the HIWIND balloon and Antarctic Jang Bogo station high latitude conjugate observations of the thermospheric winds we investigate the seasonal and hemispheric differences between the northern and southern hemispheres in June 2018.   We found that the summer (northern) hemisphere dayside meridional winds have a double hump feature, whereas in the winter (southern) hemisphere the dayside meridional winds have a single hump feature.   We attribute that to stronger summer, perhaps, northern hemisphere cusp heating.   We also compared the observation with NCAR TIEGCM (Thermosphere Ionosphere Electrodynamics General Circulation Model) and GTR (GAMERA TIEGCM RCM) models. The TIEGCM reproduced the double hump feature because of added cusp heating.    The summer hemisphere has stronger anti-sunward winds.  This is the first time we have very high latitude conjugate thermospheric wind observations.   

How to cite: Wu, Q., Lin, D., Wang, W., Qian, L., Jee, G., Lee, C., and Kim, J.: HIWIND Balloon and Antarctica Jang Bogo FPI High Latitude Conjugate Thermospheric Wind Observations and Simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3725, https://doi.org/10.5194/egusphere-egu24-3725, 2024.

EGU24-3847 | Orals | ST3.1

e3doubt: An open-source toolkit for E3D experiment planning and uncertainty estimation 

Spencer Mark Hatch, Ilkka Virtanen, and International Space Science Institute Team 506

The EISCAT_3D incoherent scatter radar presents a groundbreaking opportunity for studying a wide variety of phenomena. One of the challenges presented by such an advanced facility is its tremendous flexibility: Given a science question and an estimate of the the associated ionospheric conditions, how does one begin to design an EISCAT_3D experiment? Here we present a set of open-source tools written primarily in R and Python for estimating uncertainties of EISCAT_3D measurements of three scalar quantities (plasma density, electron and ion temperature) and one vector quantity (ion drift) for arbitrary radar configurations and different combinations of beams. Using these tools one can assess whether a candidate EISCAT_3D experiment is likely to achieve the temporal and spatial resolution needed to study a particular phenomenon, and vary parameters such as beam width, bit length, and duty cycle to understand their effect on experimental uncertainties. As a demonstration we use these tools to assess the uncertainty of maps of F-region ionospheric convection reconstructed from EISCAT_3D ion drift measurements.

How to cite: Hatch, S. M., Virtanen, I., and Team 506, I. S. S. I.: e3doubt: An open-source toolkit for E3D experiment planning and uncertainty estimation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3847, https://doi.org/10.5194/egusphere-egu24-3847, 2024.

EGU24-4444 | Orals | ST3.1

F-region ionization patches in High Frequency over-the-horizon radar data 

Gareth Perry, Katarzyna Beser, and Angeline Burrell

Ionization patches are a common feature of the polar-cap, F-region ionosphere. Patches can be detected using a variety of remote sensing instruments including optical imagers and incoherent scatter radars. Due to their pronounced plasma density gradients, patches are believed to be a strong source of decameter-scale field-aligned-irregularities which are responsible for ionospheric backscatter observed by High Frequency (HF; 3 – 30 MHz) over-the-horizon (OTH) radar systems. Indeed, Super Dual Auroral Radar Network (SuperDARN) systems at high latitudes have been used for investigating polar-cap patches for decades. Current techniques for identifying patches in SuperDARN ionospheric backscatter data are rudimentary and labor intensive as they require human intervention—an automated detection algorithm does not yet exist. This presentation will detail progress on the development of an automated algorithm for detecting patches in SuperDARN ionospheric backscatter data. The end-goal of the development effort is to transition the algorithm into a near real-time patch detection capability for SuperDARN and other OTHR systems. Patches are an important signature of magnetosphere-ionosphere-thermosphere (M-I-T) coupling in the polar regions; they are also an agent of space weather as they are a source of HF scintillation there. An automated algorithm for detecting patches will allow for their potentially hazardous influence on HF radio wave propagation conditions to be identified and mitigated.

How to cite: Perry, G., Beser, K., and Burrell, A.: F-region ionization patches in High Frequency over-the-horizon radar data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4444, https://doi.org/10.5194/egusphere-egu24-4444, 2024.

EGU24-6117 | Posters on site | ST3.1

Optical auroral spectra obtained at the Skibotn Observatory 

Hervé Lamy, Gaël Cessateur, Leo Bosse, David Bolsée, Mathieu Barthélemy, Thierry Sequies, and Magnar Gullikstad Johnsen

In October 2023, a spectrograph has been permanently installed at the Skibotn Observatory (Norway) in order to regularly monitor the auroral spectrum between ~ 400 and 700 nm with a time resolution of 30 seconds. Using a 300 lines/mm grating and a slit of 100 nm width, the wavelength resolution is approximately of 0.3 nm.  The instrument is pointing field-aligned.

The characteristics of the instrument will be provided as well as examples of spectra obtained during quiet, moderate and strong geomagnetic conditions.  A relative flux calibration is currently under way and will be discussed as well.  This will allow the computation of line ratios or a comparison with synthetic spectra obtained using kinetic transport codes such as e.g. Transsolo. Both approaches will provide an estimate of the precipitating fluxes (for electrons but also possibly for protons).

Later on we aim to provide a database of low resolution auroral spectra accessible to the community, which will nicely complement data obtained with the new EISCAT_3D radar located a few kilometers from the observatory and data from the other optical instruments located at the observatory itself.  We will also consider the possibility to obtain higher resolution spectra using a 1800 lines/mm grating during specific requested campaigns.

This project is a joint collaboration between BIRA-IASB (Belgium), IPAG (France) and UiT (Norway).

How to cite: Lamy, H., Cessateur, G., Bosse, L., Bolsée, D., Barthélemy, M., Sequies, T., and Johnsen, M. G.: Optical auroral spectra obtained at the Skibotn Observatory, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6117, https://doi.org/10.5194/egusphere-egu24-6117, 2024.

The terrestrial ionosphere is a highly variable medium that affects the propagation of radio waves. Within the ionosphere, large-scale structures, such as polar cap patches, auroral forms, blobs, and polar holes, have been observed. Small-scale irregularities associated with these large-scale structures result from instability processes which can lead to scintillation of trans-ionospheric radio signals, such as those used for Global Navigation Satellite Systems (GNSS). To investigate plasma irregularities and scintillation in the high-latitude ionosphere, the Scales of Ionospheric Plasma Structuring (SIPS) experiment was conducted using a suite of ground-based instrumentation between the 3rd and 15th of January 2024.

The aim of the SIPS experiment was to observe the high-latitude ionosphere across several scale sizes, and this required a variety of ground-based instruments, in conjunction with the Swarm satellites. The European Incoherent SCATter (EISCAT) radars were used to measure the plasma parameters, such as density, giving indication to the presence of large-scale plasma structures that were several hundreds of km in size. Medium-scale plasma irregularities, with scale sizes of several km, were inferred from the ground by the LOw Frequency ARray (LOFAR) and the Kilpisjärvi Atmospheric Imaging Receiver Array (KAIRA). Smaller-scale irregularities less than 500m in scale size were inferred from the scintillation data from ground-based GNSS receivers giving an indication to the scintillation effects. To assist in the interpretation of the results, the Swarm Ionospheric Scintillation (SWIS) methodology was also used, which utilises data from the Swarm satellites to give a spectrum of irregularities to scale sizes down to 500m (Spogli et al., 2022). Using this array of observations, the relationship between irregularities of varying scale sizes could be explored, along with the formation and generation of small-scale irregularities due to instability mechanisms and the subsequent scintillation effects which can occur.

The combination of both ground-based and space-based instruments in this experiment, observing and modelling the ionospheric plasma, gives unprecedented coverage of varying scale sizes which is not possible with individual instrumentation alone. 72 hours of EISCAT observation time was awarded for this experiment which was carried out over 5 nights in January 2024 between 18:00 and 23:59 UT. These experiments yielded a wealth of new results, the most significant of which will be discussed in this presentation.

Spogli, L., Iman, R., Alfonsi, L., Cesaroni, C., Jin, Y., Clausen, L., Wood, A., & Miloch, W. J. (2022). Feasibility of a Swarm Ionospheric Scintillation (SWIS) proxy for L-band scintillation. AGU Fall Meeting 2022.

How to cite: Maguire, S., Wood, A., and Themens, D.: Observing plasma structures at multiple scale sizes in the high-latitude ionosphere with a suite of ground-based instrumentation. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6197, https://doi.org/10.5194/egusphere-egu24-6197, 2024.

EISCAT_3D is an international research infrastructure consisting of multiple phased-array incoherent-scatter radars in the northmost areas of Norway, Finland, and Sweden. Since EISCAT_3D is capable of rapid and flexible beam steering with a high transmission power, it is considered to be potentially dual-use, as it could be used to track any objects in orbit, including military satellites. Hence, the radar system has a software component that automatically filters out the echoes from hard targets in real-time, called Hard Target Echo Removal (HTER). There are many satellites and space debris in orbit nowadays, and a large amount of data would be discarded if the HTER procedure was too simple just to throw data packets with hard target echoes.
Meanwhile, each antenna array of EISCAT_3D is composed of multiple receivers, enabling adaptive array signal processing. The direction of arrivals for the incoherent scatter and interference from hard targets would be different, as the former comes from the main lobe while the latter from the sidelobe; hence, the interference would be efficiently suppressed with the directionally-constrained minimization of power (DCMP) approach with a constraint to the loss of the signal-to-noise ratio for the incoherent scattering signal.
In this presentation, the effectiveness of the adaptive array signal processing is demonstrated on a simulation with realistic settings of the standard experiment of the EISCAT_3D to mitigate the number of discarded data with the HTER processing.

How to cite: Hashimoto, T.: Adaptive sidelobe suppression to mitigate interference from hard targets in EISCAT_3D, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7173, https://doi.org/10.5194/egusphere-egu24-7173, 2024.

EGU24-7480 | ECS | Posters on site | ST3.1

Feasibility study to estimate the ion velocity field in the F region from EISCAT_3D radar observations 

Mizuki Fukizawa, Yasunobu Ogawa, Koji Nishimura, Genta Ueno, Takanori Nishiyama, Taishi Hashimoto, and Takuo Tsuda

We conducted a feasibility study to estimate the horizontal ion velocity field in the ionospheric F region from ion velocities observed by the EISCAT_3D radar. We assumed a 27-beam configuration with a minimum elevation angle of 30 degrees. The ion velocity observation data from 200 km to 500 km altitude were projected to 200 km altitude, assuming ions above 200 km altitude follow the E x B drift. Then, we reconstructed ion velocity vectors for ±250 km in the east-west direction and ±500 km in the north-south direction at 200 km altitude. The resolution in north-south and east-west directions was 25 km. The reconstruction was conducted by maximizing a posterior probability based on Bayes’ theorem. The constraints were set to minimize the L2 norms of the following four vectors in the horizontal plane: (1) the first and (2) the second derivative of three components of the ion velocity vector, (3) the divergence of the ion velocity perpendicular to the magnetic field lines, and (4) the ion velocity parallel to the magnetic field lines. We investigated which combination of the four constraints would reconstruct the shear flow field most correctly and found that the best combination was (2), (3), and (4).

How to cite: Fukizawa, M., Ogawa, Y., Nishimura, K., Ueno, G., Nishiyama, T., Hashimoto, T., and Tsuda, T.: Feasibility study to estimate the ion velocity field in the F region from EISCAT_3D radar observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7480, https://doi.org/10.5194/egusphere-egu24-7480, 2024.

EGU24-8057 | Posters on site | ST3.1

Ionospheric absorption variation as measured by European Digisondes, riometers and determined by the NOAA D-RAP model during intense solar flares in September, 2017 

Veronika Barta, Tamás Bozóki, Dávid Péter Süle, Daniel Kouba, Jens Mielich, Tero Raita, and Attila Buzás

The sudden increase of Solar X-ray and EUV emission following solar flares causes ionization and increased absorption of electromagnetic (EM) waves in the sunlit hemisphere of the Earth’s ionosphere. Solar flares are also accompanied by energetic particles which can lead to additional ionization and absorption especially at the higher latitudes (> 60 °). A novel method has been developed by Buzás et al. [1] based on the amplitude data of the EM waves measured by Digisondes to calculate and investigate the relative absorption changes (compared to quiet period) occurring during solar flares. The effect of 13 intense (>C4.8) solar flares that occurred between 06:00 and 16:30 (UT, daytime LT = UT+2 h) from 04 to 10 September 2017 have been studied using the so-called "amplitude method". Total and partial radio fade-outs, furthermore, +20%–1400% amplitude changes (measured at 2.5 and 4 MHz) were experienced at three Digisonde stations (Juliusruh (54.63° N, 13.37° E), Průhonice (49.98° N, 14.55° E) and San Vito (40.6° N, 17.8° E)) during and after the investigated flares.

In the present study we compare the results of the amplitude method with the absorption changes measured by the Finnish Riometer Chain and determined by the NOAA D-RAP model during the same solar flare events. The X-class flares caused 1.5–2.5 dB attenuation at 30–32.5 MHz based on riometer data, while the absorption changes were between 10 and 15 dB in the 2.5–4.5 MHz frequency range (thus 10 times higher) according to the amplitude data measured by the Digisondes. The impact caused by the energetic particles after the solar flares are clearly seen in the riometer data, while it can be observed only at Juliusruh (~55°) at some certain cases among the Digisonde stations. Therefore, the absorption changes as a result of the particle precipitation is significant at high latitudes, but decreases rapidly with decreasing latitude, and is no longer detectable below the sub-auroral region. The main conclusion from the comparison of the amplitude method with the D-RAP model is that the model underestimates the values obtained from the Digisonde's measurements at both 2.5 and 4 MHz in almost every case. The differences varied between 0.2 and 15 dB at 2.5 MHz and 2.9–10 dB at 4 MHz and they did not show any systematic trend with the intensity of the flare, or with the latitude of the station. 

[1] Buzás, A., Kouba, D., Mielich, J., Burešová, D., Mošna, Z., Koucká Knížová, P., & Barta, V. (2023). Investigating the effect of large solar flares on the ionosphere based on novel Digisonde data comparing three different methods. Frontiers in Astronomy and Space Sciences, 10.

How to cite: Barta, V., Bozóki, T., Süle, D. P., Kouba, D., Mielich, J., Raita, T., and Buzás, A.: Ionospheric absorption variation as measured by European Digisondes, riometers and determined by the NOAA D-RAP model during intense solar flares in September, 2017, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8057, https://doi.org/10.5194/egusphere-egu24-8057, 2024.

EGU24-8301 | ECS | Orals | ST3.1

Post-processing and visualization of ISR data  

Juan Araujo, Stefan Johansson, Assar Westman, and Madelen Bodin

Incoherent scatter radar (ISR) techniques provide reliable measurements for the analysis of ionospheric plasma. Measurements of electron and ion densities, temperatures, and line-of-sight velocities are derived by employing antennas that transmit and receive radio waves. Recent developments in ISR technologies are capable of generating high-resolution volumetric data from multiple beam measurements. Examples of such technologies employ the so-called phased array antennas like the AMISR in North America or the upcoming EISCAT_3D in the northern Fennoscandia region. Traditional visualization methods, for example, 2D projections, applied to volumetric images render a reduced set of the available data and important aspects of the data may be lost to the analyst.
     
We present an interactive approach for the exploration and visualization of spatio-temporal and volumetric ionospheric data. The strategy is targeted at offering the analyst a wider range of alternatives in order to interpret ISR data. The proposed novel strategy allows for the reconstruction of ionospheric volume images by means of a novel sparse interpolation algorithm tailored for the particular features of ISR data. The interpolation offers estimation of gradients and processing of the challenging case of missing data. The reconstructed image is output by using volume rendering combined with customizable transfer functions. We propose to utilize reconstructed volumetric images for the estimation of ionospheric conductivities and volumetric currents, which in turn can be used for studying the evolution of storms and substorms in the ionosphere.

How to cite: Araujo, J., Johansson, S., Westman, A., and Bodin, M.: Post-processing and visualization of ISR data , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8301, https://doi.org/10.5194/egusphere-egu24-8301, 2024.

EGU24-9787 | Orals | ST3.1 | Highlight

EISCAT_3D – Volumetric Phased-Array Incoherent Scatter Radar in the European Arctic 

Thomas Ulich, Ingemar Häggström, Axel Steuwer, Anders Tjulin, Carl-Fredrik Enell, and Maria Mihalikova and the EISCAT Staff

The EISCAT Scientific Association is currently building the most advanced 3-dimensional imaging radar for atmospheric, ionospheric and near-Earth space investigations. The fully steerable, tri-static, phased-array incoherent scatter radar is located in Skibotn (inland from Tromsø, Norway), Karesuvanto (Finland, north of Kiruna), and Kaiseniemi (Sweden, west of Kiruna). The transmit-receive array at Skibotn consists of about 10,000 aerials and ten 91-aerial outrigger receivers in the immediate vicinity. The receive-only arrays of Kaiseniemi and Karesuvanto consist of about 5,000 aerials each. Construction of the facility began after the project kick-off in September 2017. During 2024, EISCAT_3D will gradually begin operations, starting with a seven-element test system and expanding from that. EISCAT_3D will replace the EISCAT mainland radars, i.e. the mono-static, 930-MHz UHF radar at Tromsø and the tri-static, 224-MHz radar at Tromsø with additional receivers at Sodankylä (Finland) and Kiruna (Sweden). The EISCAT Svalbard Radar (ESR) and the Ionospheric Heating facility at Tromsø will not be affected by EISCAT_3D becoming operational. Here we give an status update of the new facility. EISCAT_3D is a European Strategy Forum for Research Infrastructures (ESFRI) Landmark in the Environment domain.

How to cite: Ulich, T., Häggström, I., Steuwer, A., Tjulin, A., Enell, C.-F., and Mihalikova, M. and the EISCAT Staff: EISCAT_3D – Volumetric Phased-Array Incoherent Scatter Radar in the European Arctic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9787, https://doi.org/10.5194/egusphere-egu24-9787, 2024.

EGU24-9902 | ECS | Orals | ST3.1

HSS/CIR Driven Positive Ionospheric Storm at Mid-latitudes: Insights from Millstone Hill Radar and GNSS TEC measurements 

Gopika Prasannakumara Pillai Geethakumari, Anita Aikio, Lei Cai, Heikki Vanhamäki, Ilkka Virtanen, Anthea J. Coster, Aurellie Marchaudon, Pierre-Louis Blelly, Astrid Maute, Nada Ellahouny, Johannes Norberg, Shin Oyama, and Maxime Grandin

During the declining phase of the solar cycle, geomagnetic storms, primarily driven by high-speed solar wind streams (HSSs) and associated co-rotation interaction regions (CIRs), become prominent. One of the major effects of these storms are the F region electron density perturbations, usually referred to as ionospheric storms. This study focuses on a positive ionospheric storm, characterized by an increase in electron density at mid-latitudes (40°- 60° MLAT) and observed during a moderate yet prolonged HSS/CIR-driven geomagnetic storm with a SYM-H minimum of -65 nT. The storm commenced on 14 March 2016 at 17:20 UT with a strong storm sudden commencement (SSC) and lasted until 21 March. This study uses global navigation satellite system (GNSS) total electron content (TEC) data for a global perspective of electron density variations and Millstone Hill incoherent scatter radar (52° MLAT, MLT=UT-4.6) data to provide local measurements of plasma parameters during the positive storm.

In the global analysis of the TEC variations during the storm, a 6-h long strong positive ionospheric storm (TEC increase up to 50 %) at the mid-latitudes was observed in the day and dusk sectors, whereas a depletion in TEC (negative storm) prevailed at the high latitudes. The positive ionospheric storm initiated during the SSC and subsequently intensified with the onset of the main phase. The local electron density data from the Millstone Hill incoherent scatter radar showed an enhancement throughout the local evening MLTs. An uplift in the peak height together with an increased line-of-sight upward ion velocity was observed simultaneously as the traveling ionospheric disturbances (TIDs) reached Millstone Hill from the north-east direction with a phase velocity of 760 m/s. When the plasma is uplifted to greater altitudes in the F region, the recombination rate becomes slower and electron density may be enhanced. The TIDs were plausibly triggered by the Joule heating at high latitudes during the main phase of the geomagnetic storm. After the initial uplift, the peak height of electron density at Millstone Hill descended but electron densities were further enhanced. We will discuss the possible mechanisms including transportation of oxygen-rich air from high to mid latitudes when interpreting the measurements.

How to cite: Prasannakumara Pillai Geethakumari, G., Aikio, A., Cai, L., Vanhamäki, H., Virtanen, I., Coster, A. J., Marchaudon, A., Blelly, P.-L., Maute, A., Ellahouny, N., Norberg, J., Oyama, S., and Grandin, M.: HSS/CIR Driven Positive Ionospheric Storm at Mid-latitudes: Insights from Millstone Hill Radar and GNSS TEC measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9902, https://doi.org/10.5194/egusphere-egu24-9902, 2024.

Energetic proton precipitation causes proton aurora over Svalbard, but its effects on the chemistry and heat economy of the atmosphere are not well observed. Temperature and intensity changes in the OH layer have been observed during auroral electron precipitation (Suzuki et al., 2018), but no studies have yet investigated the effect of auroral proton precipitation. This study will use observations made by the HiTIES (High-Throughput Imaging Echelle Spectrograph) instrument located at the Kjell Henriksen Observatory near Longyearbyen, Svalbard. This spectrograph observes proton precipitation in the H-alpha wavelength as well as the OH*(8-3), (9-4), (5-1) airglow vibrotational bands. These OH bands are temperature and species density dependent which can be compared to the H-alpha profile and luminosity as a measure of proton aurora energy and flux. In addition, the vibrotational states above and below v'=6 result from different production processes which can be studied. Prelimiary results will be presented. 

How to cite: Dayton-Oxland, R. and Whiter, D.: Does auroral proton precipitation affect the temperature and chemistry of excited OH in the Svalbard mesopause?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10388, https://doi.org/10.5194/egusphere-egu24-10388, 2024.

EGU24-10825 | ECS | Posters on site | ST3.1

Incoherent scatter radar measurements of ion-to-neutral collision frequencies and neutral temperatures in the D-region ionosphere 

Neethal Thomas, Antti Kero, Ilkka Virtanen, and Satonori Nozawa

We have analyzed all the existing European incoherent scatter (EISCAT) radar VHF measurements carried out together with the neutral temperature measurements from LIDAR collocated at Tromsø, Norway. Incoherent scatter radar (ISR) spectral parameters are estimated from the backscattered signal autocorrelation function by fitting the D-region lag profiles (pulse-to-pulse fitting). This study focuses on the ISR spectral width which is a function of the ion-to-neutral collision frequency, neutral temperature, and ion mass. Using the neutral temperatures obtained from LIDAR, we have measured for the first time the ion-to-neutral collision frequency in the mesosphere lower thermosphere (MLT) altitude range (80-100 km) by fitting the ISR spectral width. The model ion-to-neutral collision frequencies estimated using MSIS neutral densities are found to be underestimated on average by 1.5 in comparison to the measurements. Also, the ISR collision frequencies showed large temporal variations caused by neutral density fluctuations, which are absent in the model values. These large-scale neutral density fluctuations which are thought to be caused by atmospheric waves are found to have amplitudes as large as 50% of the background density. This indicates that the ISR spectral width is largely influenced by the neutral density fluctuations. In light of these observations, the inherent limitations of inferring the neutral temperatures from ISR spectral width are studied. This study showcases the challenges of estimating neutral temperatures from ISR spectral width in the MLT altitudes, which is significant in the context of the upcoming EISCAT_3D.

How to cite: Thomas, N., Kero, A., Virtanen, I., and Nozawa, S.: Incoherent scatter radar measurements of ion-to-neutral collision frequencies and neutral temperatures in the D-region ionosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10825, https://doi.org/10.5194/egusphere-egu24-10825, 2024.

During periods of severe geomagnetic activity, auroras can be observed at much lower geomagnetic latitudes than the average auroral oval, e.g., lower than 40 degrees. Although several papers discussed the possible generation mechanisms for these auroras, their relationship with the ionospheric plasma convection pattern or the electric field distribution is not well understood, mainly because there are few observation data available.

The SuperDARN (SD) Hokkaido East and West radars, located at the lowest geomagnetic latitude among the SD radars at present, have been operating since 2006 and 2014, respectively, and observed ionospheric plasma convection patterns for three storm events in March 2015, November 2023, and December 2023, when low-latitude aurora was observed in Rikubetsu, Hokkaido, Japan (geomagnetic latitude: 37 degrees). Generally, the low-latitude auroral precipitation regions are accompanied by a shear of east-west ionospheric flows, although the detailed flow structure differs for each event. Some discussions and interpretations of these plasma flow patterns associated with the low-latitude auroras will be presented.

How to cite: Nishitani, N. and Hori, T.: SuperDARN observation of ionospheric plasma flows associated with low-latitude auroras in Hokkaido, Japan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13945, https://doi.org/10.5194/egusphere-egu24-13945, 2024.

EGU24-14785 | Orals | ST3.1

Observing auroras with dynamic vision sensors 

Andreas Stokholm, Njål Gulbrandsen, Nicolas Pedersen, Andrzej Kucik, Daniel Olesen, Anna Naemi Willer, Sine Munk Hivdegaard, and Olivier Chanrion

Auroras are a faint space weather light phenomenon caused by the interaction between the solar wind and the Earth’s magnetic field. This interaction can lead to processes that increase the energy of charged particles in the magnetosphere, enabling the particles to enter the ionosphere and cause diffuse or discrete auroras. Often, the images of auroras are captured using exposure times of 1-2 seconds to collect sufficient light. However, prolonged exposure times also intensify other light sources, such as urban- or moonlight, thus, dark night conditions are preferred. Long exposure times are also incapable of capturing fast dynamics, though some studies have carried out high-speed imaging with up to 160 frames per second (160Hz). 

Instead of traditional cameras, we propose to utilise the emerging optical technology, Dynamic Vision Sensors (DVS), that possess high dynamic ranges (110 - 120 dB) and sampling rates. DVS is a biologically-inspired silicon retina that detects negative or positive brightness change on a logarithmic scale similar to human eyes. In addition, pixels can independently adjust to lighting scenarios with an adaptable brightness threshold and without a static upper limit or constant frame rate. If no change occurs, no information is registered, providing a variable data rate and low power consumption.

Here, we present the first DVS observations of auroras in 5kHz, captured in March 2023 in Tromsø, Norway. We extract and interpret information based on reconstructed brightness and event frames. Further, we derive the incoming photon flux by mimicking a photometer. In all, we show that DVS is capable of observing auroras in challenging urban- and moonlight conditions while preserving the high temporal resolution that could enable a paradigm shift for aurora monitoring.

How to cite: Stokholm, A., Gulbrandsen, N., Pedersen, N., Kucik, A., Olesen, D., Willer, A. N., Hivdegaard, S. M., and Chanrion, O.: Observing auroras with dynamic vision sensors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14785, https://doi.org/10.5194/egusphere-egu24-14785, 2024.

EGU24-14792 | ECS | Posters on site | ST3.1

Modelling ISR plasma line frequency using ALPS dispersion relation solver  

Mini Gupta and Patrick Guio

In the Incoherent Scatter Radar (ISR) spectrum, we observe a large amount of scattered power at frequencies corresponding to plasma electrostatic modes with wavenumber imposed by the radar. The commonly occurring resonant frequencies are ion and plasma lines. Ion lines are signatures of ion-acoustic waves travelling towards and away from the radar and are observable all the time. Plasma lines are signatures of high-frequency electrostatic waves and are observable when enhanced above the thermal level by a suprathermal electron population. In this work, we assume a Maxwellian thermal population together with a suprathermal population derived from the electron transport code Aeroplanets that calculates the angular electron flux. We provide the numerical electron velocity distribution function as an input to the Arbitrary Linear Plasma Solver (ALPS) to numerically solve the linear Vlasov-Maxwell dispersion relation and estimate the resonance frequency at angles to the magnetic field. The linear resonance frequency calculated from ALPS is then compared to the resonance frequency estimated from ISR plasma line measurements.  

How to cite: Gupta, M. and Guio, P.: Modelling ISR plasma line frequency using ALPS dispersion relation solver , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14792, https://doi.org/10.5194/egusphere-egu24-14792, 2024.

EGU24-15254 | Posters on site | ST3.1

Synthetic spectra of the auroras 

Mathieu Barthelemy and Elisa Robert

The auroral emissions are due to electron precipitations into the upper atmosphere in polar regions. These electrons populations, called suprathermal, due to their high energies (10 eV to 50/100 keV) generates some emissions mainly in the green (O I 557 nm), the red (O I 630-636 nm) and the purple (N2+ 427 nm). However the spectra contains much more lines especially molecular bands such as the 1st , 2nd postive bands and the Vegard Kaplan band of molecular nitrogen which produces structured vibrational emissons. It is then important to be able to get quasi exhaustive simulations of these emissions. Based on kinetic calculations from the Transsolo code, we implemented simulations of almost all the visible emissions lines of the auroras parametized by the particle precipitations. The code used MSIS 2.0 as atmospheric model, IRI  2020 for the ionosphere and a very large set of updated cross sections. We propose in this work to present the result of these simulatins in different conditions and to consider the potential uses of such calculations for different auroral physics applications.

How to cite: Barthelemy, M. and Robert, E.: Synthetic spectra of the auroras, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15254, https://doi.org/10.5194/egusphere-egu24-15254, 2024.

EGU24-16550 | Orals | ST3.1

Improvements to the AMISR Resolved Vector Velocities Data Product 

Leslie J. Lamarche, Asti Bhatt, and Roger Varney

The Advanced Modular Incoherent Scatter Radars (AMISR) are monostatic phased-array incoherent scatter radars.  A technique for estimating the 3D plasma drift velocity vectors from line-of-sight velocity measurements across the radar field-of-view was originally published in Heinselman and Nicolls [2008].  We discuss recent improvements to this algorithm, including better error filtering and more rigorous treatment of magnetic coordinate systems, as well as a re-examination of the underlying assumptions.  These improvements result in better fidelity of the resolved vector velocities data product, which generally now cover a larger geographic area with smaller errors. Initial results are discussed, as well as next steps for the resolved vector velocities data product.

 

How to cite: Lamarche, L. J., Bhatt, A., and Varney, R.: Improvements to the AMISR Resolved Vector Velocities Data Product, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16550, https://doi.org/10.5194/egusphere-egu24-16550, 2024.

EGU24-17198 | ECS | Posters on site | ST3.1

Source regions of irregularities causing GNSS radio scintillation: An investigation using EISCAT 

Mahith Madhanakumar, Andres Spicher, Juha Vierinen, and Kjellmar Oksavik

Scintillation causing irregularities can occur in the E region or the F region ionosphere or even in both. This is due to the stochastic nature of the ionosphere that varies with the time of day, latitudes, seasons, solar and geomagnetic effects, etc. The relative importance of the different regions in hosting irregularities that can cause scintillation at GNSS frequencies in the dayside high latitude ionosphere is yet to be established. This study makes use of the 32-m European Incoherent SCATer (EISCAT) radar on Svalbard (ESR) to identify the ionospheric signatures during scintillation events. In particular, it takes advantage of the fast-scanning capability of ESR allowing it to image large areas of the ionosphere. This allows to capture ionospheric phenomena over a wide range of geographic latitudes in a short span of time. The scintillation measurements are obtained from the receiver installed at the nearby Kjell Henriksen Observatory (KHO) which can track signals from multiple GNSS constellations simultaneously. By combining the radar observations with scintillation measurements, the source regions responsible for GNSS scintillation at the dayside auroral/cusp regions are identified and characterized. The results are discussed in the context of nighttime statistics when patches and auroral dynamics are responsible for strong scintillation in GNSS signals. The results shown help better understand the impact of ionospheric irregularities on radio wave propagation in the high latitude ionosphere. Furthermore, the capability of extending the analysis to the upcoming EISCAT 3D using a simultaneous multi-beam multi-direction pattern is emphasized.

How to cite: Madhanakumar, M., Spicher, A., Vierinen, J., and Oksavik, K.: Source regions of irregularities causing GNSS radio scintillation: An investigation using EISCAT, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17198, https://doi.org/10.5194/egusphere-egu24-17198, 2024.

The mesosphere/lower-thermosphere/ionosphere (MLTI) region is a critical boundary in the coupling of the atmosphere, climate and space weather, however it is one of the least understood regions, making it hard to include in whole atmosphere models. The EISCAT radars at Tromsø (UHF and VHF) have been measuring ionospheric parameters, such as electron density, for almost 4 decades making them an excellent resource to study changes in the ionosphere over a long time period.  We have generated two data archives using 20 years of observations of EISCAT Tromsø from 2001 to 2021; the data have been re-analysed at 10-minutes and 1-hour integrations. These archives are used to study the different sources of variability in the MLTI from 50-200 km. This is the first time the mainland EISCAT data has been converted into a format that allows for long term statistical study. We have created electron density climatologies split by solar, geomagnetic and atmospheric indices to investigate the different drivers of variability in the MLTI region. We show seasonal averages of the electron density altitude profiles and compare our results to the Empirical Canadian High Arctic Ionospheric Model (E-CHAIM) and the Whole Atmosphere Community Climate Model.

How to cite: Reidy, J. and Kavanagh, A.: Investigating seasonal to decadal variability in the electron density of the mesosphere using historical EISCAT data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17646, https://doi.org/10.5194/egusphere-egu24-17646, 2024.

EGU24-17680 | Posters on site | ST3.1

Identifying sources of Ionospheric Variability: planning for EISCAT-3D operations 

Andrew J. Kavanagh, Adrian Grocott, Maria-Theresia Walach, Jade Reidy, and Mark Clilverd

The important question of how much of the variability in the high latitude ionosphere is driven by atmospheric processes as opposed to space weather impacts remains unanswered.  The EISCAT-3D radar provides a unique opportunity to probe this variability across multiple spatial and temporal scales. One of the key aims of the DRIIVE project (DRivers and Impacts of Ionospheric Variability with EISCAT-3D) is to determine the balance of energy input to the lower ionosphere and quantify the variability under different atmospheric and geomagnetic conditions.  Here we present a preliminary study of the variability using historic data from the EISCAT UHF radar taken over the course of several years in the winter months. We identify wave like signatures that occur simultaneously with Travelling Ionospheric Disturbances (TID) as seen in coherent radar data (SuperDARN), alongside enhancements due to energetic precipitation.  The magnitude of the variations are compared for different years and different driving conditions. This study will allow us to optimize the design of future experiments for EISCAT-3D to study the variability while developing effective analysis techniques to maximise utility of the new radar system.

How to cite: Kavanagh, A. J., Grocott, A., Walach, M.-T., Reidy, J., and Clilverd, M.: Identifying sources of Ionospheric Variability: planning for EISCAT-3D operations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17680, https://doi.org/10.5194/egusphere-egu24-17680, 2024.

EGU24-18848 | ECS | Posters on site | ST3.1

Splitting elemental arcs of aurora and their association with inertial Alfvén waves 

Kamalam Thillaimaharajan, Daniel Whiter, Nicholas Brindley, and Patrik Krcelic

Ground based optical observations of aurora reveal fine scale structures with brightness width less than 10 kms in the direction perpendicular to B. These fine scale structures exhibit a phenomenon called arc splitting, also known as bifurcating elemental arcs or packets. One can witness the arc splitting in the auroral image when elemental arcs peel away from a central bright arc which is then followed by the generation of new arcs. Dispersive Alfvén waves have been suggested as a possible generation mechanism for this phenomenon. Semeter et al., JGR 2008 interpreted the observations of splitting elemental arcs with respect to inertial Alfvén waves. They suggested that the energy of the precipitating electrons should decrease as the arc packets move away from the central bright arc. We tested this theory by using the data from the multi spectral imager called ASK (Auroral Structure and Kinetics) stationed on Svalbard. The energy and flux of the precipitating electrons are calculated from the ASK data and Southampton ionospheric model. We used empirical number density and IGRF (International Geomagnetic Reference Field) model to calculate the properties of the inertial Alfvén waves. A comparison between the splitting elemental arcs and Alfvén waves indicates that the wave particle interaction between Alfvén waves and the precipitating electrons is a possible generation mechanism for the production of these splitting elemental arcs. From our data and calculations, we infer an acceleration height of precipitating electrons just under 3000 km.

 

References:

Semeter, J., M. Zettergren, M. Diaz, and S. Mende (2008), Wave dispersion and the discrete aurora:

New constraints derived from high-speed imagery, J. Geophys. Res., 113, A12208.

How to cite: Thillaimaharajan, K., Whiter, D., Brindley, N., and Krcelic, P.: Splitting elemental arcs of aurora and their association with inertial Alfvén waves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18848, https://doi.org/10.5194/egusphere-egu24-18848, 2024.

EGU24-19091 | Orals | ST3.1

Latest news about the auroral emission polarisation 

Gaël Cessateur, Léo Bosse, Hervé Lamy, Jean Lilensten, Mathieu Barthelemy, and Magnar G. Johnsen

We review the last advances in the study of upper atmospheric emissions polarisation. Since 2008, observations and modeling initiatives aimed at detecting and understanding the auroral emission polarisation. In recent years, this field saw major advances, which confirm the ionospheric origin of the polarisation. Polarisation has been observed in all four main auroral visible emissions lines (the red (630 nm), green (557.7 nm), blue (427.8) and purple (391.4 nm)), in several geomagnetic and auroral activity levels and has been confirmed for the N2+ lines through laboratory experiments. However, the origin of this polarisation is still debated. Several points show that it cannot be due to atmospheric scattering, and must originate from ionosphere. The link between the polarisation state of the emission and the local ionospheric conditions is still uncertain and raises a number of questions, such as: Can ground based measurements of the polarisation with light instruments track ionospheric currents? What is the origin of the green line polarisation?

Our international collaboration gathers several instruments dedicated to the observations of the auroral emission polarisation, mainly located at the Skibotn observatory in Norway. The CRU series instruments, which are spectro-photo polarimeters able to measure faint polarized signals in a 2° FOV, are coupled with PLIP, for Polar Lights Imaging Polarimeter, able to measure polarization of the three main auroral emissions on a large FOV (~44° × 30°) on the sky. Some results will be presented from our last observation campaigns in Skibotn, Norway. Combining the CRU instruments with the PLIP imager opens a new chapter of investigation.

How to cite: Cessateur, G., Bosse, L., Lamy, H., Lilensten, J., Barthelemy, M., and Johnsen, M. G.: Latest news about the auroral emission polarisation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19091, https://doi.org/10.5194/egusphere-egu24-19091, 2024.

EGU24-19428 | Posters on site | ST3.1

Embla: A new optical instrument to measure auroral precipitation, neutral temperature and electric fields at high resolution 

Daniel Whiter, Jonathan Rae, Srimoyee Samaddar, Patrik Krcelic, Betty Lanchester, Ishbel Carlyle, Nicholas Brindley, Kamalam Thillaimaharajan, and Robert Fear

We have constructed a new high-resolution auroral imager, called Embla, to simultaneously measure energy and flux of auroral precipitation, neutral temperature, and electric fields in fine scale aurora. Embla is designed primarily for studies of auroral electrodynamics, substorm onset, and neutral heating by aurora. The instrument has recently been installed at Skibotn, Norway, very close to the EISCAT_3D radar transmitter site, and we expect the combination of radar and optical observations to enable better measurements for our science than either instrument can provide alone.

Embla builds on work done using the Auroral Structure and Kinetics (ASK) instrument, which has been stationed at the EISCAT Svalbard Radar since 2007. Embla has a spatial resolution in the E-region of ~30 m and a planned temporal resolution of at least 32 frames per second, allowing us to resolve the fine-scale structure and rapid dynamics of auroral features. It consists of 4 co-aligned imagers with identical 9 degree fields of view centred on magnetic zenith. Each imager is equipped with a different narrow passband interference filter, targetting emissions in N2 1P (2 imagers), OI 777.4 nm, and O+ 2P. The combination of N2 1P and OI 777.4 nm observations allows us to image the characteristic energy and flux of auroral electron precipitation. The O+ 2P emission has a long lifetime of 5 s, providing a means to observe ion drift perpendicular to the magnetic field and therefore a way to determine ionospheric electric fields at very high cadence in localised regions around the aurora. Finally, by combining observations from two of the imagers in separate regions of the N2 1P band we can image the neutral temperature at the altitude of the auroral emission. The simultaneous measurement of these properties of the aurora and ionosphere will allow us to investigate auroral electrodynamics in detail.

How to cite: Whiter, D., Rae, J., Samaddar, S., Krcelic, P., Lanchester, B., Carlyle, I., Brindley, N., Thillaimaharajan, K., and Fear, R.: Embla: A new optical instrument to measure auroral precipitation, neutral temperature and electric fields at high resolution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19428, https://doi.org/10.5194/egusphere-egu24-19428, 2024.

EGU24-20593 | Orals | ST3.1

Vertical features of the ionospheric holes during rocket launches observed by the Sanya Incoherent Scattering Radar 

Feng Ding, Xinan Yue, Yihui Cai, Junyi Wang, and Linxuan Zhao

Previous observations shows that during rocket launches, the water in the plume released by rockets usually caused a wide range of ionosphere electron density depletion. While a number of publications devoted to the horizontal variations of such ionosphere holes, observation of the vertical features of ionosphere holes has seldom been reported. In this paper, we used the Sanya Incoherent Scattering Radar (SYISR) to observe the vertical variations of the ionosphere hole during two rocket launch events in year 2022. Both the rockets passed through the topside ionosphere over the China South Sea, with an estimated minimum distance of ~100-300 km from SYISR. About ~15 min after the rocket launch, we observed the ionosphere hole with an altitude range of ~200-800 km. The maximum electron density depletion of -20% occurred at ~420 km, with a duration of 2.2 hours. Based on the observations, we discussed the diffusion of water molecules and its influences on altitude distribution of the ionosphere holes during the rocket launches.

How to cite: Ding, F., Yue, X., Cai, Y., Wang, J., and Zhao, L.: Vertical features of the ionospheric holes during rocket launches observed by the Sanya Incoherent Scattering Radar, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20593, https://doi.org/10.5194/egusphere-egu24-20593, 2024.

EGU24-900 | ECS | Posters on site | ST3.3

Identification of Two-Step Non-linear Interactions via Zonally Symmetric Waves during Major Sudden Stratospheric Warmings 

Gourav Mitra, Amitava Guharay, Fede Conte, and Jorge Chau

This study delved into atmospheric tides and their dynamics during two major boreal sudden stratospheric warmings (SSWs). Using meteor radar wind data, our investigation unveiled compelling indications of non-linear interactions between the semidiurnal solar tide and the quasi-20-day wave (Q20dw) in the high latitude mesosphere and lower thermosphere (MLT) during SSWs. Additionally, the diagnosis of zonal wavenumbers indicated potential non-linear interaction between the dominant semidiurnal migrating tide (SW2) and the zonally symmetric 20-day wave (20dw0) component, generating secondary waves. The study emphasized the significance of the non-linear interaction between the zonal wavenumber 2 component of the stationary planetary wave (SPW2) and the westward propagating 20-day wave (20dwW2) in the stratosphere, crucial in producing the 20dw0. The meteor radar wind spectra suggested that the excited 20dw0 possibly engages in non-linear interactions with SW2, further generating secondary waves in the MLT. Therefore, this study presents the observational evidence of a two-step non-linear interaction associated with zonally symmetric planetary waves during major SSWs.

How to cite: Mitra, G., Guharay, A., Conte, F., and Chau, J.: Identification of Two-Step Non-linear Interactions via Zonally Symmetric Waves during Major Sudden Stratospheric Warmings, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-900, https://doi.org/10.5194/egusphere-egu24-900, 2024.

EGU24-1861 | ECS | Posters on site | ST3.3

Behaviour Of Temperature During Wintertime Reversal Of Zonal Wind  

Sunil Kumar Ramatheerthan, Michal Kozubek, and Jan Laštovička

Climatologically, the wintertime-evolved stratospheric polar vortex comprises zonal wind, which is westerly. During extreme events like Sudden Stratospheric Warming (SSW), the polar vortex disrupts, showing easterly wind at stratospheric altitudes. Defining extreme events in the stratosphere, like SSW at a definite pressure scale, depends on the region explaining its effects. For instance, the standard definition of SSW is 10 hPa pressure suites primarily for the lower atmosphere. SSW's current definition is unsuitable for the upper atmosphere, especially the ionosphere. So, with this viewpoint, we study the fundamental behaviour of the zonal mean of temperature during the reversal of the zonal mean of zonal wind by using superposed epoch analysis. We use the MERRA2 dataset for this analysis. From MERRA-2, we analyse the zonal mean of temperature and zonal wind from 1980 – 2022 northern hemispheric winters. The analyses are done at 10 hPa, where the standard definition of SSW is defined, and at 1 hPa, 0.5 hPa and 0.1 hPa. Temperature behaviours at different reversal periods are studied at various latitudinal values, starting at 60oN and ending at 90oN. With this analysis, a more general picture of the temperature–wind relation can be understood, which will help to understand and define SSW in a much better way for upper atmospheric studies.

How to cite: Ramatheerthan, S. K., Kozubek, M., and Laštovička, J.: Behaviour Of Temperature During Wintertime Reversal Of Zonal Wind , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1861, https://doi.org/10.5194/egusphere-egu24-1861, 2024.

EGU24-1897 | ECS | Orals | ST3.3

 Three-dimensional modeling of the O2(1Δ) dayglow  and implications for ozone in the middle atmosphere. 

Mouhamadou Diouf, Franck Lefevre, Alain Hauchecorne, and jean-loup Bertaux

Future space missions dedicated to measuring CO2 on a global scale can make advantageous use of the O2 band at 1.27 µm to retrieve the air column. The 1.27 µm band is close to the CO2 absorption bands at 1.6 and 2.0 µm, which allows a better transfer of the aerosol properties than with the usual O2 band at 0.76 µm. However, the 1.27 µm band is polluted by the spontaneous dayglow of the excited state O2(1Δ), which must be removed from the observed signal.

We investigate here our quantitative understanding of the O2(1Δ) dayglow with a chemistry-transport model. We show that the previously reported -13% deficit in O2(1∆) dayglow calculated with the same model is essentially due a -20 to -30% ozone deficit between 45-60 km. We find that this ozone deficit is due to excessively high temperatures (+15 K) of the meteorological analyses used to drive the model in the mesosphere.

The use of lower analyzed temperatures (ERA5), in better agreement with the observations, slows down the hydrogen-catalyzed and Chapman ozone loss cycles. This effect leads to an almost total elimination of the ozone and O2(1Δ) deficits in the lower mesosphere. Once integrated vertically to simulate a nadir measurement, the deficit in modeled O2(1Δ) brightness is reduced to -4±3%. This illustrates the need for accurate mesospheric temperatures for a priori estimations of the O2(1Δ) brightness in algorithms using the 1.27 µm band.

How to cite: Diouf, M., Lefevre, F., Hauchecorne, A., and Bertaux, J.:  Three-dimensional modeling of the O2(1Δ) dayglow  and implications for ozone in the middle atmosphere., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1897, https://doi.org/10.5194/egusphere-egu24-1897, 2024.

EGU24-2764 | ECS | Orals | ST3.3

Observed responses of tides and gravity waves in the MLT region to the Madden-Julian Oscillation 

Xu Zhou, Xinan Yue, Libo Liu, Guiwan Chen, Xian Lu, You Yu, and Lianhuan Hu

This work analyzed the intraseasonal variability of non-migrating tides DE3 and gravity wave momentum fluxes (GWMF) in the mesosphere and lower thermosphere (MLT) region and discussed the possible connection with the tropospheric MJO. Based on the joint observations of the TIMED-TIDI satellite and the 120°E meridian meteor radar chain, we revealed a significant broad-band intra-seasonal signal in the DE3 amplitude around the equator with a clear seasonal dependence. The intraseasonal variability of DE3 in zonal winds (DE3-U) has a strong amplitude in boreal winter, up to 1-2 times the seasonal average, while the variability is usually within 20% during other seasons. The response of MLT DE3 tides to the MJO in different seasons was further discussed together with the MJO activity index. The results suggested that the DE3-U in boreal winter generally has a larger amplitude during MJO phases 4–6 (~10%–40%), while the amplitude is smaller for other MJO phases (~−10%–−40%). As for the GWMF estimation, the 12-year continuous observation of the Mohe meteor radar (53.5°N, 122.3°E) was analyzed. The results showed that intraseasonal GWMF variability is also prominent during boreal winter. Composite analysis for DJF season according to MJO phases revealed that the zonal GMWFs notably increased in MJO P4 by ~2–4 m2/s2, and a Monte Carlo test was designed to examine the statistical significance. The response in zonal winds differs from the GMWF response by two MJO phases (i.e., 1/2π). Additionally, time-lagged composites revealed the strengthened westward GWMF occurred ~25–35 days after MJO P4, coincident with the MJO impact on the polar vortex as previous works revealed. Overall, this work emphasized that the tropical sources (MJO) impress the intraseasonal signal from the troposphere to the MLT region, either tropics or extratropics.

How to cite: Zhou, X., Yue, X., Liu, L., Chen, G., Lu, X., Yu, Y., and Hu, L.: Observed responses of tides and gravity waves in the MLT region to the Madden-Julian Oscillation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2764, https://doi.org/10.5194/egusphere-egu24-2764, 2024.

EGU24-2910 | ECS | Orals | ST3.3

Quantifying the impact of variable solar forcing on Sudden Stratospheric Warmings (SSWs) 

Monali Borthakur and Miriam Sinnhuber

Sudden stratospheric warmings (SSWs) are characterised by the rise of polar stratospheric temperatures by several tens of kelvins. Here, we investigate the SSW of 2009 using the ECHAM/MESSy (EMAC) chemistry climate model. We study in particular how the SSWs are affected by variable solar forcing: EUV photo-ionisation that dominates the changes during high solar activity and geomagnetic storms. The warmings are preceded by a slowing then reversal of the westerly winds in the stratospheric polar vortex which then becomes easterly and it is also closely associated to polar vortex breakdown. 20 ensemble members are considered and different onset dates of the free running ensembles for the SSW event in January are tested to see the development of the polar vortex and its breakdown in the different ensemble members. Ionisation rates from the AISSTORM model are used in this case. And the results are compared with a geomagnetic storm (consisting of mostly electrons that are in the range of a few kilo-electron volts (keVs) to about 1 MeV) included on the day of the SSW, i.e., 25th of January. For the experiments considered here, the EUV photoionization was doubled and halved, and in both cases an increase in stratospheric temperature compared to the normal EUV was observed. Overall, effects of both EUV photoionization and particles on the temperature, wind fields, NOy and ozone in the middle atmosphere was observed. As ozone is one of the key species in radiative heating and cooling of the stratosphere, changes in its concentration can be linked to dynamical changes in the middle atmosphere.

 

How to cite: Borthakur, M. and Sinnhuber, M.: Quantifying the impact of variable solar forcing on Sudden Stratospheric Warmings (SSWs), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2910, https://doi.org/10.5194/egusphere-egu24-2910, 2024.

EGU24-2912 | Orals | ST3.3 | Highlight

WACCM-X simulations with NAVGEM-HA meteorological analyses and SABER observations of mesosphere and lower thermosphere temperature  

Guiping Liu, Jeffrey Klenzing, Sarah McDonald, Fabrizio Sassi, and Douglas Rowland

Realistic modeling of the dynamics and variability in the mesosphere and lower thermosphere (MLT) is significant to understand the coupling of the whole atmosphere system. Here we present the simulations of the MLT temperatures at ~100 km altitude for one year during 2014 by Whole Atmosphere Community Climate Model with thermosphere-ionosphere extension (WACCM-X) constrained below ~90 km using meteorological analysis products of the high-altitude version of Navy Global Environmental Model (NAVGEM-HA). The model results are sampled at the same times and locations as the satellite observations from Thermosphere Ionosphere and Mesosphere Electric Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry (TIMED/SABER). Comparisons of the daily mean temperatures show that the observed and modeled values are correlated (correlation coefficient equals to ~0.5-0.7) at latitudes away from the equator. Both the observations and simulations reveal an annual variation at mid-latitudes with the temperature maximum in summer and minimum in winter, and at lower latitudes the semiannual variation becomes stronger having the temperature maximums at equinoxes and minimums during solstices. However, the temperatures observed are on average ~5-10 K (3-5%) smaller than the model and the observations show a larger variability across all latitudes between 50oS-50oN. The WACCM-X simulations with constrains by NAVGEM-HA meteorological analyses are overall consistent with the SABER observations though some differences are noticed. Whole atmosphere models with high altitude observation constrains would be useful to improve the numerical simulations of the MLT variability and the atmosphere and ionosphere coupling.

How to cite: Liu, G., Klenzing, J., McDonald, S., Sassi, F., and Rowland, D.: WACCM-X simulations with NAVGEM-HA meteorological analyses and SABER observations of mesosphere and lower thermosphere temperature , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2912, https://doi.org/10.5194/egusphere-egu24-2912, 2024.

EGU24-3615 | Orals | ST3.3

Drivers for different behaviors in storm-time thermospheric O/N2 ratio and nitric oxide density 

Yongliang Zhang, Wenbin Wang, and Larry Paxton

Geomagnetic storms lead to significant depletion/enhancement in O/N2 column density and enhancement in nitric oxide (NO) in the thermosphere.  The O/N2 depletion is generally anti-correlated with NO enhancement on a global scale. However, the NO enhancement often extends beyond the equatorward edge of O/N2 depletion in latitude and/or the range of O/N2 depletion in longitude on a local scale. These behaviors are most likely driven by the storm-time equatorward wind that brings the O/N2 depleted and NO enhanced air from high to low latitudes, as well as zonal wind perturbations. On the other hand, the equatorward wind also depends on altitudes. Note that the peak NO density locates at an altitude around 110 km while the O/N2 column density is mostly contributed by local O andN2 density around 140 km and above. The different behaviors between NO and O/N2 are likely due to the altitude variations of the meridional winds during storms as revealed by TIEGCM simulations. The downward advection by vertical winds associated with storm-time meridional circulation perturbations may also contribute to the difference.

How to cite: Zhang, Y., Wang, W., and Paxton, L.: Drivers for different behaviors in storm-time thermospheric O/N2 ratio and nitric oxide density, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3615, https://doi.org/10.5194/egusphere-egu24-3615, 2024.

EGU24-3860 | Orals | ST3.3

Satellite mega-constellations and spacecraft re-entry: Are we harming Earth’s atmosphere? 

Karl-Heinz Glassmeier and Leonard Schulz

Satellite mega-constellations are one of the main reasons for the current exponential growth of space flight. The increasingly large number of objects in orbit has already raised much concern about space debris and requires mitigation strategies. The common strategy for low Earth orbit (LEO) objects is to ensure their re-entry into Earth’s atmosphere, where they ablate and burn up, injecting material into the mesosphere and lower thermosphere. We discuss the significance of this anthropogenic injection compared to the natural one originating from meteoric sources, which provide a constant flow of cosmic dust and larger meteoroids into Earth’s atmosphere. Our comparison indicates that already in 2019 the anthropogenic mass injection has been significant (2.8%) compared to the natural injection. This number will rise in the future due to the ongoing implementation of satellite mega-constellations. More than 5,000 constellation satellites are in orbit right now with more than 100,000 proposed. Considering a worst-case scenario, the injection of metals could increase up to 90% and the aerosol injection up to 94% compared to the natural injection. As the material is mainly injected into mesosphere heights, possible influences on mesospheric and even stratospheric chemistry, with effects on the ozone layer, cloud formation or the climate are thinkable. Recent, first observations already confirmed the existence of spacecraft ablation remnants in stratospheric aerosol particles. This  emphasizes our theoretically conjectured significance of anthropogenic dust injection . However, further studies, including observations and modeling, are urgently required to further elucidate any atmospheric effects. Precautions need to be discussed now in order to protect our atmosphere from yet another human-made influence, that is space waste.

How to cite: Glassmeier, K.-H. and Schulz, L.: Satellite mega-constellations and spacecraft re-entry: Are we harming Earth’s atmosphere?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3860, https://doi.org/10.5194/egusphere-egu24-3860, 2024.

EGU24-4681 | Posters on site | ST3.3

Overview of the impact of climate change on the structure and dynamical properties of the stratosphere 

Juan A. Añel, Laura de la Torre, Aleš Kuchař, Rolando García, Marty M. Mlynczak, Celia Pérez Souto, and Petr Šácha

Climate change has a significant impact on the structure and properties of the Earth's atmosphere above the tropopause. The most noticeable effects include a decrease in temperature and density. However, it is difficult to establish trends for this region of the atmosphere, which includes the stratosphere and above. This is mainly due to the need for long-term datasets to ensure that the trends are robust and statistically significant. It is also necessary to consider the impact of solar influence when trying to quantify the role of anthropogenic emissions on various variables' trends.

In this study, we explore all these issues, including the effects of different metrics on quantification and trends such as differences in geopotential levels, temperature, density, and the width of the layers. To achieve this, we use a combination of reanalysis and satellite data. The results take into account global mean values and latitudinal differences. We observe a contraction and cooling of the stratosphere in all layers, but with some variations.

How to cite: Añel, J. A., de la Torre, L., Kuchař, A., García, R., Mlynczak, M. M., Pérez Souto, C., and Šácha, P.: Overview of the impact of climate change on the structure and dynamical properties of the stratosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4681, https://doi.org/10.5194/egusphere-egu24-4681, 2024.

Time series of mesosphere/lower thermosphere half-hourly winds over Collm (51.3°N, 13.0°E) have been obtained from 1984 – 2008 by low frequency (LF) spaced receiver measurements and from 2004 to date by VHR meteor radar Doppler wind observations in the height range 82 – 97 km.  From half-hourly differences of zonal and meridional winds, gravity wave (GW) proxies have been calculated that describe amplitude variations in the period range 1 – 3 hours. After applying corrections to account for instrumental differences, GW climatology and time series have been obtained. The mean GW activity in the upper mesosphere shows maximum amplitudes in summer, while in the lower thermosphere GWs maximize in winter. Positive/negative long-term trends are visible in winter/summer. Interannual and quasi-decadal variations of GW amplitudes are also visible, but these are intermittent.

 

How to cite: Jacobi, C., Karami, K., and Kuchar, A.: Long-term trends of mesosphere/lower thermosphere gravity wave proxies derived from combined LF spaced receiver and VHF Doppler wind observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4692, https://doi.org/10.5194/egusphere-egu24-4692, 2024.

EGU24-4991 | Posters on site | ST3.3

Laboratory Studies Relevant to the Coupled OH Meinel and O2 Atmospheric Band Emissions 

Konstantinos Kalogerakis

The hydroxyl radical plays an important role in the photochemistry of the Earth's mesosphere. The OH Meinel band emission dominates the visible and near-infrared portion of the nightglow spectrum. A detailed knowledge of the rate constants and relevant pathways for OH(high v) vibrational relaxation by atomic and molecular oxygen is essential for understanding mesospheric OH emissions and extracting reliable chemical heating rates from atmospheric observations. We have developed laser-based experimental methodologies to study the complex collisional energy transfer processes involving the OH radical and other relevant atmospheric species. Our previous studies have indicated that the total removal rate constant for OH(v = 9) by atomic oxygen at room temperature is more than one order of magnitude larger than that for removal by molecular oxygen. Thus, O atoms are expected to significantly influence the intensity and vibrational distribution extracted from the mesospheric OH(v) Meinel band emissions. This is a progress report on our experimental studies investigating OH(v ≥ 5) + O vibrational relaxation and the implications for mesospheric nightglow.

This work is supported by the NASA Heliophysics Program under Grant 80NSSC23K0694 and the National Science Foundation (NSF) under Grants AGS-2009960 and AGS-2113888.

How to cite: Kalogerakis, K.: Laboratory Studies Relevant to the Coupled OH Meinel and O2 Atmospheric Band Emissions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4991, https://doi.org/10.5194/egusphere-egu24-4991, 2024.

For more than 60 years, field strength measurements of the broadcasting station, Allouis (Central France), have been received at Kühlungsborn (54° N, 12° E), Mecklenburg, Northern Germany. Beginning with the year 1959 these so-called indirect phase-height measurements of low frequency radio waves (with a frequency of about 162 kHz) are used to examine trends and the long-term oscillations over Western Europe. The advantages of this method are the low costs and the simplicity of operation. Results of the updated fifth release (R5, 1959-2019) of standard-phase heights (SPH) are presented.

The statistical analysis of the SPH series shows a significant overall trend with a decrease of 116 m per decade indicating a subsidence of the long-radio wave reflection height of about 700 m during R5. As expected the daily time series of SPH shows in its spectrum dominant modes which are typical for the solar cycle, ENSO and for QBO bands, indicating solar and lower atmospheric influences. Solar cycle and ENSO (-QBO)-like band-pass show a growing increase of SPH up to 1987, followed by a decrease afterwards.

For summer months during solar minimum years, without solar influences and without stratopause altitude trend, a thickness temperature trend of the mesosphere is significant with a trend value of -0.47 ± 0.43 K/ decade. The overall cooling of the intrinsic mesospheric temperature during 60 years of observation is in the order of 3 K. 

How to cite: Peters, D. H. W. and Mani, S.: More than 60 years of measurements of Standard-Phase-Heights over Western Europe – Trends and long-term oscillations of the mesosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5620, https://doi.org/10.5194/egusphere-egu24-5620, 2024.

EGU24-7694 | Posters on site | ST3.3

The nature of mesopause jumps as simulated with the nudged KMCM model 

Urs Schaefer-Rolffs, Christoph Zülicke, and Franz-Josef Lübken

Mesopause jumps are a phenomenon that is only observed in the southern summer MLT region. The mesopause is lifted by several kilometers within a few days and then later returns to its original altitude accompanied by strong cooling. Lidar and radar measurements indicate that these jumps are the result of a late breakdown of the polar jet, which occurs frequently in the southern hemisphere. Although the basic mechanism is known, no successful simulations of such mesopause jumps have yet been performed.

In my talk, I will present a case study using the Kühlungsborn Mechanistic general Circulation Model (KMCM) in which nudging is applied. I will compare measurements of the austral summers 2010/11, 2011/12 and 2012/13 obtained with lidars and radars over the Davis station in Antarctica at 69°S with simulations performed with the KMCM. Mesopause jumps were detected in the first two summers, while no jump occurred in the last summer.

In general, our simulations show that the KMCM with nudging is able to reproduce mesopause jumps. In November and December, the simulations agree quite well with the observations, and we can better understand the role of gravity waves in the mechanism of mesopause jumps. In January and February, however, the simulations seem to be too active, as the agreement with the observations is less good.

How to cite: Schaefer-Rolffs, U., Zülicke, C., and Lübken, F.-J.: The nature of mesopause jumps as simulated with the nudged KMCM model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7694, https://doi.org/10.5194/egusphere-egu24-7694, 2024.

EGU24-8574 | Posters on site | ST3.3

The future of nuctilucent clouds 

Franz-Josef Lübken, Gerd Baumgarten, Mykhaylo Grygalashvyly, and Ashique Vellalassery

Noctilucent clouds (NLC) consist of water ice particles which appear in the summer mesopause region at middle and polar latitudes. They owe there existence to extremely low temperatures present in this part of the atmosphere. We have applied the background model LIMA (Leibniz Institute Model
of the Atmosphere) and a microphysical model MIMAS (Mesospheric Ice Microphysics And tranSport model) to study the long term historical development of NLC. More recently, we extended these studies including future climate change predictions by modifying the concentration of carbon dioxide and methane. Carbon dioxide leads to a cooling of nearly the entire middle atmosphere (fostering the conditions for the presence of NLC), whereas methane is nearly completely converted to water vapor in the mesosphere leading to larger and more abundent ice particles, i. e., to brighter and more frequent NLC. In this study we present model simulations of the future development of NLC. We investigate typical NLC parameters, such as mean particle radius, ice number densities, and backscatter coefficients, and their relationship to background conditions (temperature, water vapor). It turns out that ice particle parameters (size, backscatter) are nearly entirely determined by the amount of water vapor, whereas the (geometric) altitude of NLC is mainly given by a shrinking of the atmosphere (due to cooling) below NLC altitudes. The effective transport of water vapor known as `freeze drying' leads to a significant enhancement (nearly doubling) of water vapor at NLC heights within this century.

How to cite: Lübken, F.-J., Baumgarten, G., Grygalashvyly, M., and Vellalassery, A.: The future of nuctilucent clouds, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8574, https://doi.org/10.5194/egusphere-egu24-8574, 2024.

The chemical composition of Earth's lower thermosphere around an altitude of 180 km remains a largely uncharted territory. This altitude marks a critical transition region, where the atmosphere shifts from being dense and collision-dominated to a regime of free molecular flow. In this region, the altitude profiles of the present chemical species demonstrate their steepest gradients, a phenomenon crucial for understanding the dynamic interplay between the lower thermosphere and the mesosphere. Despite its importance, this region remains poorly explored due to limited in situ observations. Our focus is on the deployment of a highly miniaturized mass spectrometer, specifically designed for a CubeSat platform where it will be accommodated within 1U. This advanced instrumentation is designed to measure in situ all species present in this part of the atmosphere. Thanks to its novel ion source design, it is capable of measuring atoms, molecules, radicals, and isotopes, with exceptional sensitivity, dynamic range, mass range, and mass resolution even at the hyper-velocities of spacecraft during these measurements. The core of our discussion revolves around the expected data quality and performance capabilities of this mass spectrometer, particularly its operation at the perigee in the lower thermosphere. The data obtained from this innovative approach are expected to shed light on the complex dynamics at play in this scarcely studied region. We anticipate that these findings will significantly contribute to the scientific community’s understanding of the lower thermosphere, its coupling with the mesosphere, and the exosphere, filling a crucial gap in our current knowledge and potentially paving the way for future research in both atmospheric science and comparative planetology.

How to cite: Fausch, R. and Wurz, P.: Towards in situ measurements of the chemical composition of Earth’s lower thermosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8857, https://doi.org/10.5194/egusphere-egu24-8857, 2024.

EGU24-9229 | Posters on site | ST3.3

A novel gravity wave transport parametrization for global chemistry climate models: description and validation  

Wuhu Feng, Maria-Vittoria Guarino, Chester S. Gardner, Bernd Funke, Maya Garcıa-Comas, Manuel Lopez-Puertas, Marcin Kupilas, Daniel R. Marsh, and John M.C. Plane

The gravity wave drag parametrization of the Whole Atmosphere Community Climate Model (WACCM) in the NCAR Community Earth System Model version 2 (CESM2) has been modified to include the wave-driven atmospheric vertical mixing caused by propagating, non-breaking, gravity waves. The strength of this atmospheric mixing is represented in the model via the “effective wave diffusivity” coefficient (Kwave).  Using Kwave, a new total dynamical diffusivity (KDyn) is defined. KDyn represents the vertical mixing of the atmosphere by both breaking (dissipating) and vertically propagating (non-dissipating) gravity waves. Here we show that, when the new diffusivity is used, the downward fluxes of Fe and Na between 80 and 100 km are largely increased. Larger meteoric ablation injection rates of these metals (within a factor 2 of measurements) which were reduced by a factor of 5 in the WACCM, can now be used in the developed WACCM version, which produce Na and Fe layers in good agreement with lidar observations. Mesospheric CO2 is also significantly impacted, with the largest CO2 concentration increase occurring between 80-90 km, where model-observations agreement improves. However, in regions where the model overestimates CO2 concentration, the new parametrization exacerbates the model bias. The mesospheric cooling simulated by the new parametrization, while needed, is currently too strong almost everywhere. The summer mesopause in both hemispheres becomes too cold by about 30K compared to observations, but it shifts upward, partially correcting the WACCM low summer mesopause.

Our results highlight the far-reaching implications and the necessity of representing vertically propagating gravity waves in climate models. This novel method of modelling gravity waves contributes to growing evidence that it is time to move away from dissipative-only gravity wave parametrizations.

How to cite: Feng, W., Guarino, M.-V., Gardner, C. S., Funke, B., Garcıa-Comas, M., Lopez-Puertas, M., Kupilas, M., Marsh, D. R., and Plane, J. M. C.: A novel gravity wave transport parametrization for global chemistry climate models: description and validation , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9229, https://doi.org/10.5194/egusphere-egu24-9229, 2024.

EGU24-9230 | ECS | Orals | ST3.3

Small-scale waves, big implications: a regionally refined perspective with the Whole Atmosphere Community Climate Model 

Marcin Kupilas, Chester Gardner, Wuhu Feng, Maria Vittoria Guarino, Daniel Marsh, and John Plane

State-of-the-art global chemistry-climate models such as WACCM cannot practically resolve the small-scale gravity waves (GWs) that are important in the mesosphere and lower thermosphere (MLT, ≈ 70-120km). A solution is the use of parametrizations that represent subgrid dissipating GWs (see e.g. Garcia et al., 2007). To reproduce key MLT features such as mesospheric jet reversals, pole-to-pole circulation and the summer mesopause, models rely on such schemes (McLandress, 1997; Holton & Alexander, 2000), though more development is needed. For example, WACCM tends to underestimate observed mesospheric densities of O, O3 and NO, and overestimate observed densities of the Na and Fe layers produced from cosmic dust ablation. Increasing evidence suggests a reason for this is a missing vertical transport from subgrid propagating GWs, and a solution has recently been achieved when these effects were included in the WACCM GW scheme (Guarino et al., 2023). In the current work, we resolve subgrid waves natively using WACCM with Regional Refinement (WACCM-RR). WACCM-RR provides the unprecedented opportunity to model the global climate up to altitudes of 140 km, and resolve individual regions down to as far as 1/32° at a low computational cost compared to global high resolution models. Trends from a model using a 1/8° grid over the Continental US  (1° elsewhere), when compared to a global 1° model, are consistent with comparisons of standard WACCM models, to models using our updated GW scheme. For example, mesospheric densities of O, O3 and CO2 are increased, as predicted. A surprising contrast is a globally warmer atmosphere, likely due to sensitivity of the meridional circulation to GW activity in the refined region. The results point to the applicability of WACCM-RR for detailed investigations of wave-transport processes, and their impact on MLT dynamics and composition. We point out remaining questions and challenges.

How to cite: Kupilas, M., Gardner, C., Feng, W., Guarino, M. V., Marsh, D., and Plane, J.: Small-scale waves, big implications: a regionally refined perspective with the Whole Atmosphere Community Climate Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9230, https://doi.org/10.5194/egusphere-egu24-9230, 2024.

EGU24-9572 | ECS | Posters on site | ST3.3

Global scale gravity wave observations and analysis with the ESA Earth Explorer 11 candidate CAIRT 

Sebastian Rhode, Manfred Ern, Peter Preusse, Jörn Ungermann, Inna Polichtchouk, Kaoru Sato, Shingo Watanabe, Wolfgang Woiwode, and Martin Riese

The ESA Earth Explorer 11 Candidate CAIRT is a prime candidate for reliably observing gravity wave (GW) activity throughout the middle atmosphere up to the MLT region from about 15 km to 90 km altitude. A horizontally panning spectrometer with limb viewing geometry allows for the measurement of 3-dimensional temperature fields with high vertical resolution that can be used to quantify the global GW distributions and spectra as well as individual GW events. The detected horizontal spectrum of GWs would cover scales of about 100 km and above. Here, we show how the temperature retrieved by CAIRT can be utilized for characterizing GW parameters such as wave vector, amplitude, and phase. This wave-based approach allows for a precise estimation of the GW momentum flux (GWMF) and its development and distribution in the middle atmosphere, e.g., during an SSW event. The vertical resolution of the data is high enough for estimating the GW drag, shedding light on the role of GWs during global-scale dynamic phenomena. In addition, we show the applicability of using ray tracing the estimated GWs along the orbit tracks, which provides a means for increased horizontal coverage and better representation of GW drag due to accounting for horizontal propagation of the GWs.

How to cite: Rhode, S., Ern, M., Preusse, P., Ungermann, J., Polichtchouk, I., Sato, K., Watanabe, S., Woiwode, W., and Riese, M.: Global scale gravity wave observations and analysis with the ESA Earth Explorer 11 candidate CAIRT, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9572, https://doi.org/10.5194/egusphere-egu24-9572, 2024.

EGU24-10171 | Orals | ST3.3

EPP-climate link by reactive nitrogen polar winter descent revisited: MIPAS v8 reprocessing and future benefits by the EE11 candidate mission CAIRT 

Stefan Bender, Bernd Funke, Manuel Lopez Puertas, Maya Garcia-Comas, Gabriele Stiller, Thomas von Clarmann, Michael Höpfner, Björn-Martin Sinnhuber, Miriam Sinnhuber, Quentin Errera, Gabriele Poli, and Jörn Ungermann

Polar winter descent of reactive nitrogen (NOy) produced by energetic particle precipitation (EPP) in the mesosphere and lower thermosphere affects polar stratospheric ozone by catalytic reactions. This, in turn, may have implications for regional climate via radiative and dynamical feedbacks. NOy observations taken by the MIPAS/Envisat instrument during 2002--2012 have provided observational constraints on the solar-activity modulated variability of stratospheric EPP-NOy amounts. These constraints have allowed to formulate a chemical upper boundary condition for climate models in the context of solar forcing recommendations for CMIP6. Recently, a reprocessed MIPAS version 8 dataset has been released. Compared to the previous version, we assess what impact the changes in this new data version have on the EPP-NOy quantification, and on the formulation of chemical upper boundary conditions for climate models.

The Earth Explorer 11 candidate “Changing Atmosphere Infra-Red Tomography” (CAIRT) will observe the altitude region from about 5 km to 115 km with an across-track resolution of 30 to 50 km within a 500 km wide field of view. This instrument will provide NOy and dynamical tracer observations from the upper troposphere to the lower thermosphere with unprecedented spatial resolution. Given that neither MIPAS nor any of the current instruments observes the lower thermosphere at this spatial resolution, we will assess the potential of this mission to advance our understanding of the EPP-climate link in the future.

How to cite: Bender, S., Funke, B., Lopez Puertas, M., Garcia-Comas, M., Stiller, G., von Clarmann, T., Höpfner, M., Sinnhuber, B.-M., Sinnhuber, M., Errera, Q., Poli, G., and Ungermann, J.: EPP-climate link by reactive nitrogen polar winter descent revisited: MIPAS v8 reprocessing and future benefits by the EE11 candidate mission CAIRT, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10171, https://doi.org/10.5194/egusphere-egu24-10171, 2024.

EGU24-11840 | ECS | Posters on site | ST3.3 | Highlight

Impact of Terrestrial Weather on the MLTI Region as Examined from Satellite Constellations and Model Run 

Sovit Khadka, Federico Gasperini, Jens Oberheide, and Martin Mlynczak

The mesosphere, lower thermosphere, and ionosphere (MLTI) region of the Earth’s atmosphere connects the Sun and the lower atmosphere, displaying various physical and electrodynamical processes. This transition region exhibits intermittent, daily, seasonal, annual, and solar cycle variability and that can be probed in-situ or remotely to gain insights into the impact of solar as well as terrestrial weather. This study presents the response of the MLTI system to the global-scale waves (GSWs) in terms of the spatial and temporal variations of temperature, plasma, and neutral density from the simultaneous observations by the multi-satellite constellations. Comparisons of these with model results can provide an opportunity to monitor evolutions, variations, and coupling of their GSW structures in the MLTI region. The temperature, plasma, and neutral density variations were diagnosed concurrently from the Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics (TIMED)‐Sounding of the Atmosphere using Broadband Emission Radiometry (SABER), Defense Meteorological Satellite Program (DMSP), Constellation Observing System for Meteorology, Ionosphere and Climate 2 (COSMIC-2) observations, and Swarm-C satellite constellations, respectively, during 2020-2021 for solar minimum and geomagnetic quiet conditions. Additionally, for the first time, we used an updated version of the Climatological Tidal Model of the Thermosphere (CTMT) to analyze the vertical-temporal-latitudinal tidal structures of temperature and density. The updated CTMT uses solar flux dependent Hough Mode Extensions (HMEs), includes a more extensive collection of TIMED Doppler Interferometer (TIDI) data, compiles SABER V2.08, restructures ion drag and dissipation, and provides tidal components for individual years. We extract the wavenumber (WN) patterns along longitudes in the form of temperature, neutral and electron densities from satellites data, assuming a fixed local time. We then examine tidal components from the new version of CTMT to determine modeling evidence for the variation and coupling of the GSWs under similar conditions. Thereby, we compare the reconstructed WN structures from tidal components obtained from the updated CTMT with the evaluated GSW patterns from the satellite-borne dataset. Using satellite observations and new CTMT approaches, we investigate the impact of terrestrial weather and possible factors that trigger variability, interaction, and coupling processes mediated by GSWs to the MLTI system within ±45o latitudes.

How to cite: Khadka, S., Gasperini, F., Oberheide, J., and Mlynczak, M.: Impact of Terrestrial Weather on the MLTI Region as Examined from Satellite Constellations and Model Run, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11840, https://doi.org/10.5194/egusphere-egu24-11840, 2024.

EGU24-12716 | Posters on site | ST3.3

New Routine for Calculating the non-LTE CO2 15 μm Cooling of Mesosphere and Lower themosphere in GCMs 

Alexander Kutepov and Artem Feofilov

The 15 μm CO2 radiative cooling h has significant impact on the energy budget of mesosphere and lower thermosphere (MLT).  Exact calculations of h are critically important for adequate modeling the pressure and temperature distributions in MLT by General Circulation Models (GCMs). Large errors of current routines calculating h significantly influence pressure and temperature distributions in MLT obtained by GCMs. In this study we analyze the errors of the most widely used parameterization of h by Fomichev et al, (1998) and show, that very large errors this parameterization has for temperature profiles disturbed by waves (up to 25 K/Day at mesopause region) are caused by a very approximate solution of the non-local thermodynamic equilibrium (non-LTE) problem. These errors may not be removed in the framework of the parameterization approach, as the revised version of the Fomichev-98 algorithm presented by Lopez-Puertas et al, (2023), shows (see Kutepov, 2023).

Instead of developing a new parameterization we present (Kutepov and Feofilov, 2023) for the first time the routine for exact calculating the non-LTE h of MLT in GCMs. The routine is an optimized version of the ALI-ARMS (for Accelerated Lambda Iterations for Atmospheric Radiation and Molecular spectra) non-LTE research code (Feofilov and Kutepov, 2012). It delivers h for day and night conditions with an error (for the current CO2 density) not exceeding 1 K/Day even for strong temperature disturbances. The routine uses the ALI and the Opacity Distribution Function (ODF) techniques adopted from the modeling of stellar atmospheres, and is about 1000 faster than the standard matrix/line-by-line non-LTE solution algorithms. It has an interface for feed-backs from the model, is ready for implementation, may use any quenching rate coefficient of the CO22 )+O(3P) reaction, handles large variations of O(3P), and allows the user to vary the number of vibrational levels and bands to find a balance between the calculation speed and accuracy. The routine can handle the broad variation of CO2 both below and above the current volume mixing ratio, up to 4000 ppmv. This allows using this routine for modeling the Earth’s ancient atmospheres and the climate changes caused by increasing CO2. The routine may be downloaded from https://doi.org/10.5281/zenodo.8005028.

Reference

López-Puertas, M., at al. An improved and extended parameterization of the CO2 15 μm cooling in the middle/upper atmosphere,https://doi.org/10.5194/egusphere-2023-2424. Preprint. Discussion started: 6 November 2023, 2023.

Feofilov, A. G. and Kutepov, A. A. Infrared Radiation in the Mesosphere and Lower Thermosphere: Energetic Effects and Remote Sensing, Surveys in Geophysics, 33, 1231–1280, https://doi.org/10.1007/s10712-012-9204-0, 2012.

Fomichev, V. I., et al. Matrix parameterization of the 15 µm CO2 band cooling in the middle and upper atmosphere for variable CO2 concentration, Journal of Geophysical Research: Atmospheres, 103, 11 505–11 528, 475 https://doi.org/10.1029/98jd00799, 1998.

Kutepov, A. A, and Feofilov A. G. New Routine NLTE15μmCool-E v1.0 for Calculating thenon-LTE CO2 15 μm Cooling in GCMs of Earth’s atmosphere, Geophysical Model Development (discussion), https://doi.org/10.5194/gmd-2023-115, 2023.

Kutepov, A. A., 'Comment on “An improved and extended parameterization … by Lopez-Puertas et al, 2023, https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2424/egusphere-2023-2424-CC1-supplement.pdf, 2023.

How to cite: Kutepov, A. and Feofilov, A.: New Routine for Calculating the non-LTE CO2 15 μm Cooling of Mesosphere and Lower themosphere in GCMs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12716, https://doi.org/10.5194/egusphere-egu24-12716, 2024.

EGU24-12721 | ECS | Orals | ST3.3 | Highlight

It's Not Easy Being Green: Quantitative Modeling of STEVE's Picket Fence Emissions Driven by Local Parallel Electric Fields 

Claire Gasque, Reza Janalizadeh, Brian Harding, Megan Gillies, and Justin Yonker

The vibrant green streaks of the 'picket fence' typically appear below a STEVE arc in the subauroral sky, at lower latitudes than the auroral oval. Recent studies suggest that, despite its aurora-like appearance, the picket fence may not be driven by magnetospheric particle precipitation but instead by local electric fields parallel to Earth's magnetic field. In this study, we investigate this hypothesis by quantitatively comparing observed picket fence optical spectra with emissions generated in a kinetic model driven by parallel electric fields in a realistic neutral atmosphere. We find that sufficiently large parallel electric fields can reproduce the observed ratio of N2 first positive to oxygen green line emissions, without producing N2+ first negative emissions. We find that, at a typical picket fence altitude of 110 km, parallel electric fields between 40 and 70 Td (~80 to 150 mV/m at 110 km) result in calculated spectral features consistent with observed ones, providing a benchmark for future observational and modeling studies. Additionally, we review studies which have identified similar features to the picket fence in the aurora, suggesting that a similar mechanism may be at work there. Since visible and ultraviolet auroral emissions are increasingly used to infer magnetospheric activity, it is important to better understand and quantify potential sources of emission beyond particle precipitation.

How to cite: Gasque, C., Janalizadeh, R., Harding, B., Gillies, M., and Yonker, J.: It's Not Easy Being Green: Quantitative Modeling of STEVE's Picket Fence Emissions Driven by Local Parallel Electric Fields, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12721, https://doi.org/10.5194/egusphere-egu24-12721, 2024.

Lightning-ionosphere interactions are well documented in the form of observations of fantastic optical emissions such as sprites and elves.  In order to better understand electromagnetic heating of the lower ionosphere (∼60-100 km altitude), a mesospheric photo-chemistry model is employed to interpret lightning-ionosphere interactions. The LIMA atmospheric chemistry model implements >150 chemical reactions, as do similar atmospheric chemistry models, such as WACCM, but the LIMA model has had success modeling so-called Long Recovery Events. Due to the large number of reactions and chemical species involved, however, it can be difficult to identify specific cause and effect mechanisms for the event of interest. This paper presents a simplified mesospheric chemistry model that accurately reproduces lightning-ionosphere interactions predicted by the full 167-reaction LIMA model (it maintains the accuracy of the full LIMA model for electron density, electron temperature, electrical conductivity, and electromagnetic field intensity as a function of time and space throughout the heating process).

How to cite: Moore, R. and Santos, J.: Lightning-Ionosphere Interactions: An Accurate, Simplified Nighttime Mesospheric Photochemistry Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14619, https://doi.org/10.5194/egusphere-egu24-14619, 2024.

EGU24-15169 | ECS | Orals | ST3.3

Exceptional bright OH airglow night at Cerro Paranal, Chile, with high wave activity and sudden brightness depletion 

Patrick Hannawald, Carsten Schmidt, Sabine Wüst, Alain Smette, and Michael Bittner

The dynamics in the atmosphere, especially the upper mesosphere and mesopause are significantly driven by atmospheric gravity waves. OH airglow offers an unique possibility to observe atmospheric dynamics in this altitude region with a high spatio-temporal resolution simultaneously using imager and spectrometer systems. Especially, characteristics of gravity waves as well as features like wave breaking and wave-wave interaction can be observed. Spectroscopic observations allow observing rotational temperature changes. Thus, both instrument types complement each other very well.

Since November 2022 two airglow imagers (FAIM) and one airglow spectrometer (GRIPS) with high temporal resolution (1 image every 2 seconds, 1 spectrum every 15 seconds) started routine observations during each night in cooperation with and at ESO’s Very Large Telescope (VLT) in the Atacama Desert at Cerro Paranal, Chile (24.6°S, 70.4°W).

During the night from 31st July to 1st August 2023 we observed an exceptional bright night that is much brighter than any other we observed so far: a single wave front propagates from West to East with an observed phase speed of about 60m/s. After the passing of the wave front the OH intensity decreases by around 50% within only one hour. Pronounced wave activity of small-scale waves is observed especially before the passing of the event. Similar events in literature are often stated as “wall events”, but seem to occur very rarely in the extent observed.

We present and interpret the wall event and discuss the observed phenomenon and its causes using data from multiple instruments and data sources.

How to cite: Hannawald, P., Schmidt, C., Wüst, S., Smette, A., and Bittner, M.: Exceptional bright OH airglow night at Cerro Paranal, Chile, with high wave activity and sudden brightness depletion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15169, https://doi.org/10.5194/egusphere-egu24-15169, 2024.

EGU24-15654 | Posters on site | ST3.3

Comparison of different stratospheric parameters from reanalysis and satellite data 

Laura de la Torre, Juan A. Añel, Petr Šácha, Aleš Kuchař, Rolando García, and Martin G. Mlynczak

In this study we compare various stratospheric parameters obtained from reanalysis and satellite data. The data from ERA5.1, MERRA2, JRA55, and JRA3Q reanalysis, as well as from the MLS and SABER satellite instruments are used to assess the agreement between reanalysis and satellite data in the stratospheric layer. In particular, the geopotential height of the tropopause and stratopause, as well as the stratospheric thickness, are computed and compared. The results show that the most significant discrepancies are observed in the tropics (30ºS to 30ºN) and the global mean, where negative correlations with satellite data are found. The correlations in the southern hemisphere extratropics are lower than those in the northern hemisphere extratropics. Moreover, the stratospheric thickness, a priori expected to be well-correlated with the stratospheric temperature, not always behaves this way.

How to cite: de la Torre, L., Añel, J. A., Šácha, P., Kuchař, A., García, R., and Mlynczak, M. G.: Comparison of different stratospheric parameters from reanalysis and satellite data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15654, https://doi.org/10.5194/egusphere-egu24-15654, 2024.

Atomic oxygen is one of the main species in the mesosphere and lower thermosphere (MLT) of the Earth’s atmosphere. Thus, atomic oxygen and the local temperature plays an important role for the energy balance in the MLT region. By remote sensing of the emission from the atomic oxygen fine-structure transitions at 2.06 THz and the 4.74 THz, atomic oxygen concentration profiles and neutral temperature profiles of the atmosphere can be derived.  By resolving the line profile, heterodyne spectroscopy enables access to layers of the atmosphere for which the oxygen line is saturated. The first spectrally resolved measurements of the 4.74-THz line of atomic oxygen in the atmosphere were performed with the heterodyne spectrometer GREAT on board of the airborne astronomic observatory SOFIA [1]. Based on the experiences from GREAT, the heterodyne spectrometer OSAS-B was developed as a balloon-borne instrument dedicated to the measurement of atomic oxygen in Earth’s atmosphere [2].

In this study, we investigate the feasibility of a satellite-borne heterodyne spectrometer for the retrieval of atomic oxygen concentration and temperature in the MLT. Compared to airborne observations, a satellite instrument has the advantage of a limb observation geometry which facilitates the retrieval. A satellite instrument also has the advantage of a fast and almost global coverage.

For investigating the feasibility of such an instrument, we use the vertical density and temperature profiles provided by the NRLMSIS 2.0 atmosphere model to simulate 2.06 THz and 4.74 THz emission spectra as measured by a satellite. We then apply retrieval algorithms for the atomic oxygen concentration and temperature and compare the retrieved profiles to the reference, i.e. the original NRLMSIS 2.0 profiles. We consider the scenario of a satellite in a circular orbit at an altitude of 500 km and an inclination of 8°. The emission spectra are simulated using radiative transfer under the assumption of local thermodynamic equilibrium.

By considering two separate heterodyne receivers with sensitivity of 11,000 K and 25,000 K noise temperature for the 2.06 THz and 4.74 THz lines, respectively, and data accumulated over 100 seconds of measurement time, corresponding to a ground track of 700 km, we can retrieve a vertical temperature profile from 100 km altitude to 300 km altitude with 5 % relative uncertainties and an atomic oxygen concentration profile from 120 km to 300 km with 5 % relative uncertainties. From 100 km to 120 km the uncertainty in the atomic oxygen concentration is higher and within 25 %.

[1] Richter, H. et al. Commun Earth Environ 2,19 (2021), doi: 10.1038/s43247-020-00084-5

[2] Wienold, M. et al. 48th IRMMW-THz, Montreal, Canada (2023), doi: 10.1109/IRMMW-THz57677.2023.10299165

How to cite: Hansen, P. B., Wienold, M., and Hübers, H.-W.: Feasibility study of a satellite-borne terahertz heterodyne spectrometer for the retrieval of atomic oxygen and temperature in the Earth's atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15735, https://doi.org/10.5194/egusphere-egu24-15735, 2024.

EGU24-16986 | Orals | ST3.3 | Highlight

Gravity Waves and Turbulence indicating multistep vertical coupling near the Polar Vortex Edge 

Gerd Baumgarten, Eframir Franco-Diaz, Jens Fiedler, Michael Gerding, Ralph Latteck, Mohammed Mossad, Toralf Renkwitz, Irina Strelnikova, Boris Strelnikov, and Robin Wing

Throughout the winter, extreme circumpolar wind patterns are found in the altitude range of 30 to 70 km, reaching wind speeds up to 500 km/h. The circumpolar wind patterns form the Stratospheric Polar Vortex. In the Northern Hemisphere, weather extremes are known to be linked to distortions of the Polar Vortex. Recently, studies using observations and modelling have indicated that the extreme winds at the Polar Vortex Edge also play a crucial role in multistep upward coupling through gravity waves. Variations in the wind profiles affect gravity wave propagation and lead to wave generation and breakdown. Direct measurements of the mean winds and waves at the Polar Vortex Edge are rare and technically challenging. We use lidar and radar instruments to measure temperature, wind, and the occurrence of layered phenomena over northern Norway (ALOMAR, 69°N) and northern Germany (Kühlungsborn, 54°N). Using more than 10 years of measurements, we have collected a unique dataset, which contains measurements both inside and outside the Polar Vortex.

These observations are used to explore upward- and downward-propagating gravity waves in the complex dynamical setting near the Polar Vortex Edge. These unique wave-vortex interactions play a role in coupling layers above and below, and link large-scale flow to turbulence, frequently observed as layered phenomena, such as Polar Mesosphere Winter Echoes. The link between waves, turbulence, and the polar vortex will be discussed using observations and model data.

 

How to cite: Baumgarten, G., Franco-Diaz, E., Fiedler, J., Gerding, M., Latteck, R., Mossad, M., Renkwitz, T., Strelnikova, I., Strelnikov, B., and Wing, R.: Gravity Waves and Turbulence indicating multistep vertical coupling near the Polar Vortex Edge, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16986, https://doi.org/10.5194/egusphere-egu24-16986, 2024.

The circulation in the Mesosphere / Lower Thermosphere (MLT) region is strongly influenced by atmospheric gravity waves that propagate upward from the lower atmosphere. So far, most global models of the MLT have to parameterize gravity waves, given horizontal model resolution on the order of 100 km. It becomes increasingly clear that the simplified approximations of gravity wave parameterizations, including their inability to simulate gravity wave generation within the middle atmosphere, are a cause for biases in the simulation of MLT circulation, holding back scientific progress in understanding, predicting and projecting MLT circulation.

In this study, the extended German Weather and Climate model UA-ICON is used to demonstrate the effects of moving from a coarse model resolution to a gravity-wave permitting resolution on the simulation of the mean state of the MLT and its predictability. An episode of austral winter to spring is simulated with two UA-ICON set-ups, one with about 160 km horizontal grid spacing and 120 vertical levels from the ground to 150 km height (“coarse resolution”), and one with about 20 km horizontal grid spacing and 250 vertical levels (“high resolution”). The high-resolution set-up is able to resolve gravity waves with horizontal wave length up to about 200 km. Resolving gravity waves is essential to simulate the mean state of MLT circulation in austral winter: while in the coarse resolution model, zonal mean winds around 100 km height are easterly, the high-resolution model version simulates westerlies in this region, in agreement with observations. It is shown that wave forcing by resolved waves with horizontal scales below 2000 km, which are only resolved in the high-resolution model version, impose an eastward force on the zonal mean winds, and thus are essential to maintain the westerly winds. Next to the mean state, the two model set-ups are utilized to demonstrate the effects of resolving gravity waves on estimations of the intrinsic predictability of the MLT region: experiments with imposed small perturbations in the initial conditions show that error growth in the MLT region is substantially faster in the high-resolution simulation with resolved gravity waves compared to the coarse resolution simulation. Thus, the intrinsic predictability time-scale, after which the MLT becomes intrinsically unpredictable, is vastly overestimated by a factor of 3-4 in simulations that do not resolve gravity waves. Overall, this work stresses the importance of exploring high-resolution simulations of the MLT in order to make progress on our understanding of MLT dynamics.

How to cite: Garny, H.: Predictability and mean state of the MLT: Importance of resolving gravity waves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17136, https://doi.org/10.5194/egusphere-egu24-17136, 2024.

EGU24-20214 | Orals | ST3.3 | Highlight

The Changing-Atmosphere Infra-Red Tomography Explorer (CAIRT) Earth Explorer 11 candidate mission 

Bernd Funke, Martyn Chipperfield, Quentin Errera, Felix Friedl-Vallon, Sophie Godin-Beekmann, Michael Hoepfner, Alex Hoffmann, Alizee Malavart, Scott Osprey, Inna Polichtchouk, Peter Preusse, Piera Raspollini, Björn-Martin Sinnhuber, Pekka Verronen, and Kaley Walker

The Changing-Atmosphere Infra-Red Tomography Explorer (CAIRT) is currently in Phase A as one of two final candidates for ESA’s Earth Explorer 11. As a Fourier transform infrared limb imager, CAIRT will observe simultaneously from the middle troposphere to the lower thermosphere at high spectral resolution and with unprecedented horizontal and vertical resolution. With this, CAIRT will provide critical information on (a) atmospheric gravity waves, circulation and mixing, (b) coupling with the upper atmosphere, solar variability and space weather and, (c) aerosols and pollutants in the upper troposphere and  lower stratosphere. In this presentation we will give an overview of CAIRT’s science goals and the expected mission performance, based on latest results from feasibility studies performed during Phase 0. 

How to cite: Funke, B., Chipperfield, M., Errera, Q., Friedl-Vallon, F., Godin-Beekmann, S., Hoepfner, M., Hoffmann, A., Malavart, A., Osprey, S., Polichtchouk, I., Preusse, P., Raspollini, P., Sinnhuber, B.-M., Verronen, P., and Walker, K.: The Changing-Atmosphere Infra-Red Tomography Explorer (CAIRT) Earth Explorer 11 candidate mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20214, https://doi.org/10.5194/egusphere-egu24-20214, 2024.

EGU24-21520 | Orals | ST3.3 | Highlight

Long-term changes in gravity wave activity in the middle atmosphere from satellite and ground-based observations 

Neil Hindley, Lars Hoffmann, Tracy Moffat-Griffin, Phoebe Noble, and Corwin Wright
Atmospheric gravity waves (GWs) are one of the most important drivers of the circulation of the middle and upper atmosphere. Usually generated in the lower atmosphere and propagating upwards through the atmospheric layers, the aggregated forcing of these waves drives circulations in the middle atmosphere that are far from that expected under radiative equilibrium. Circulations in the mesosphere and lower thermosphere (MLT) and above, especially in polar regions, have shown extreme sensitivity to GW parameterisations in recent high-top modelling simulations and can exhibit significant and limiting biases compared to observations. This uncertainty in the role of GW dynamics between models has made predictions of how these high-altitude circulations are expected to respond to a changing climate very challenging. This is confounded by a relative scarcity of global observations of GW activity in the middle and upper atmosphere with which to understand these connections over climate timescales. Since the early 2000s, satellite and ground-based instrumentation has provided an unprecedented observational view of middle atmospheric dynamics and composition, especially for the study of GWs. However, due to different instrument capabilities and limited hardware lifetimes, examining long term trends of GW properties observationally has been challenging due to the need to re-establish baselines. Here we examine results from some of the longest known single-instrument records of GW activity in the middle and upper atmosphere spanning more than two decades. We explore changes in GW amplitudes, wavelengths and directional momentum flux in the stratosphere from a 22-year climatology derived from global 3-D satellite observations from the AIRS/Aqua, the longest single-instrument climatology of this type. We also explore changes in wind, temperature and large-scale GW activity in the polar MLT from nearly 20 years of single-station meteor wind radar observations in the Arctic and Antarctic. We compare these trends to equivalent analysis of other long-term satellite GW datasets and resolved GW activity in ERA5 stratospheric reanalysis. Finally, we discuss limitations and best practise for considering observed trends in GW observations, such as how changes in circulation can affect GW propagation and their apparent sensitivity to satellite remote sensing techniques.

How to cite: Hindley, N., Hoffmann, L., Moffat-Griffin, T., Noble, P., and Wright, C.: Long-term changes in gravity wave activity in the middle atmosphere from satellite and ground-based observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21520, https://doi.org/10.5194/egusphere-egu24-21520, 2024.

EGU24-21525 | ECS | Posters on site | ST3.3

Advective transport between the stratosphere and mesosphere 

Radek Zajíček, Petr Šácha, Petr Pišoft, and Jiří Mikšovský

The Brewer-Dobson circulation (BDC) characterizes the large-scale meridional overturning mass circulation influencing the composition of the whole middle atmosphere. The BDC consists of two separate parts - a shallow branch in the lower stratosphere and a deep branch higher in the middle atmosphere. The BDC is analytically usually defined as consisting of a diffusive part and an advective residual mean. Climate model simulations robustly show that the advective BDC part accelerates due to greenhouse gas-induced climate change and this acceleration strongly influences middle atmospheric chemistry and physics in climate model projections. A prominent quantity that is being studied as a proxy for advective BDC changes is the net tropical upwellling, commonly at the tropopause level or in the lower stratosphere. The upper branch of the BDC received considerably less research attention than its shallow part, although it features important atmospheric mechanisms. It couples the stratosphere and mesosphere and is responsible for a large portion of interhemispheric transport in the middle atmosphere. Aiming to fill this gap, we present a multi-model study of climatology and trends in advective mass transport across the vertically shifting stratopause. Results based on ensembles of 7 CCMI models include decomposition of long-term changes in cross-stratopause transport into individual terms such as acceleration of the residual circulation itself, vertical shift of the stratopause, changes in width of the upwelling region and changes in the shape of the stratopause.

How to cite: Zajíček, R., Šácha, P., Pišoft, P., and Mikšovský, J.: Advective transport between the stratosphere and mesosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21525, https://doi.org/10.5194/egusphere-egu24-21525, 2024.

EGU24-1288 | Posters on site | ST3.4

Different long-term trends of foF2 with different solar activity indices 

Jan Laštovička

I use yearly average noontime foF2 from six ionospheric stations from four continents, Juliusruh, Pruhonice, Roma, Boulder, Kokubunji and Canberra over periods 1976-1995 and 1996-2014, and six solar activity indices F10.7, F30, Mg II, solar H Lyman-α flux, sunspot numbers and He II. The results reveal somewhat and sometimes even substantially different trends of foF2 when the effect of solar cycle is removed/reduced from foF2 data with different solar activity proxies. Only F30 provides for all stations and both periods the trends of the same sign (negative), other indices reveal both positive and negative trends for different stations and periods. Therefore together with results of other criteria F30 is considered to be the most reliable solar activity index for long-term studies of midlatitude foF2.

 

How to cite: Laštovička, J.: Different long-term trends of foF2 with different solar activity indices, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1288, https://doi.org/10.5194/egusphere-egu24-1288, 2024.

EGU24-1426 | ECS | Posters on site | ST3.4

Solar variability and delayed ionospheric response: Insights from complex 27-day solar EUV signatures 

Hanna Dühnen, Rajesh Vaishnav, Erik Schmölter, and Christoph Jacobi

The solar extreme ultraviolet (EUV) radiation drives the major ionization processes in the upper atmosphere. Its variability causes a related response in ionospheric observables. Especially of interest is the delayed response of electron density (Ne), integrated total electron content (TEC), and the density of major neutral and ionized species to the 27-d solar rotation period. But this solar signature is often influenced by underlying trends on shorter and longer time-scales. Therefore, this study examines the ionospheric response to a solar 27-d signature superposed with a long-term increase in solar EUV, showing that complex composition changes in the upper atmosphere influence the expected response significantly. Using high-resolution simulations of the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIE-GCM), we compare two different 27-d solar rotation periods from the year 2014 with enhanced solar activity. This allows us to compare an almost ideal solar activity input with one that is superposed with an increase in solar activity. The main results show that the accumulation of ionized species O+ and O2+ in the lower ionosphere, especially up to the maximum density of ionized oxygen (O+) at about 230 km, is significantly affected by the long-term increase in solar activity.  Nevertheless, the 27-d solar rotation period dominates the ionization in both, ideal and complex model run for altitudes above 230 km. Thus, our results are in good agreement with preceding studies and extend the study of the delayed ionospheric response to more complex cases.

How to cite: Dühnen, H., Vaishnav, R., Schmölter, E., and Jacobi, C.: Solar variability and delayed ionospheric response: Insights from complex 27-day solar EUV signatures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1426, https://doi.org/10.5194/egusphere-egu24-1426, 2024.

EGU24-2232 | Orals | ST3.4

Modeling the occurrence probability of sporadic-E based on GNSS radio occultation data 

Dieter Bilitza, Vladimir Truhlik, Christina Arras, and Haris Haralambous

Sporadic E (Es) layers are a well-known ionospheric phenomenon, whose occurrence can cause anomalous propagation of radio waves utilized for communication and broadcast. Es layers are very thin layers of metallic ions such as Fe+, Mg+, and Ca+ formed  mainly by atmospheric tidal wind shears.  Their peak density exceeds the E-layer peak density and can even exceed the F-layer peak density. Because of their effect on radio waves a user needs to know when there is a high probability of Es occurrence. It is the goal of this study to develop a global model of Es occurrence probability and to make it publicly available through inclusion in the International Reference Ionosphere (IRI).

We use Es data obtained by Arras et al. (2022) from GNSS radio occultation observations from various satellites (CHAMP, Spire, KOMPSAT-5, COSMIC1 & 2, TANDEM-X, and TerraSAR-X) for the time period 2001-2022. We will briefly discuss the variation of the Es occurrence rate with latitude, longitude, local time, season, solar activity, and magnetic activity. as observed with this data base. We found that the strongest dependencies are with local time, latitude and season, while weaker ones exist with longitude and solar activity. We use spherical harmonics to describe the global expansion of the strongest influences establishing a core model. Second order influences, e.g., solar activity variations, are modelled as a perturbation on the core model. First results obtained with the new model will be presented.

References

Arras, C., Resende, L.C.A., Kepkar, A. et al. Sporadic E layer characteristics at equatorial latitudes as observed by GNSS radio occultation measurements. Earth Planets Space 74, 163 (2022). https://doi.org/10.1186/s40623-022-01718-y

 

How to cite: Bilitza, D., Truhlik, V., Arras, C., and Haralambous, H.: Modeling the occurrence probability of sporadic-E based on GNSS radio occultation data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2232, https://doi.org/10.5194/egusphere-egu24-2232, 2024.

GDC is a six-satellite constellation, designed to investigate the dynamics of the coupling between the ionosphere and thermosphere. The mission will provide multipoint observations of both the energy inputs and the ionosphere-thermosphere system response with sufficient spatial and temporal resolution to finally unravel the physical processes underlying the observed system-level dynamical responses. A critical component of the measurement requirements are the characteristics of the thermal plasma. TPS is a multi-sensor instrument designed to measure the three components of the ion drift, the ion density and temperature, and the mass fractions of the major constituent ions. We present an overview of the instrument, the methods by which the measurements are made, and the science questions to be addressed.

How to cite: Anderson, P.: The Thermal Plasma Sensor (TPS) for the Geospace Dynamics Constellation (GDC) mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3589, https://doi.org/10.5194/egusphere-egu24-3589, 2024.

Gravity waves (GWs) are an important class of atmospheric waves that can propagate from the troposphere up to the upper atmosphere, where they can contribute significantly to the dynamical changes in the ionosphere. The aim of the present contribution is to gain a deeper understanding of the coupling between the lower and the middle ionosphere via gravity waves by the concurrent analysis of narrowband VLF measurements (characterizing GWs in the E layer) carried out at the Tihany Geophysical Observatory (TGO), Hungary and the multi-point and multi-frequency continuous Doppler sounding system (characterizing GWs in the F layer) operated by the Institute of Atmospheric Physics, CAS in the Czech Republic. The signal from the German VLF transmitter (call sign: DHO, frequency: 23.4 kHz) detected at the TGO have been considered for the present study, since the Doppler system located in the western part of the Czech Republic is close to the midpoint of the DHO-TGO wave propagation path. The inferred gravity wave activities have also been compared with the lightning locations provided by the World Wide Lightning Location Network (WWLLN) in order to identify the possible source areas of the upward propagating gravity waves. 

The preliminary analysis was carried out for the summer months of 2021. From the narrowband VLF measurements, the day-to-day variation of the average GW activity for each night was determined using the Wavelet transform. In the case of the Doppler system, the estimated Doppler shifts and the spreadF proxy were used to characterize the nighttime GW activity. Our results show low correlation (~0.04) between GW activity inferred from the VLF and Doppler measurements. On the other hand, for both the VLF and Doppler measurements, we could identify certain areas where the large number of lightning strokes was associated with enhanced GW activity in the corresponding ionospheric measurement. However, the areas found for the two measurements do not overlap, which may indicate that the VLF measurement is sensitive to a different area where the Doppler system is located. This work has been supported by the PITHIA-NRF Trans-National Access (TNA) programme.

How to cite: Bozóki, T. and Chum, J.: Comparison of gravity waves detected in the lower ionosphere by narrowband VLF measurements and in the F layer by a continuous Doppler sounding system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3841, https://doi.org/10.5194/egusphere-egu24-3841, 2024.

EGU24-5871 | ECS | Orals | ST3.4

Modelling sporadic E (Es) layers in WACCM-X: Presenting a new methodology for the identification of Es layers, and the resulting climatology 

Tasha Aylett, Wuhu Feng, Daniel Robert Marsh, and John Maurice Campbell Plane

Sporadic E (Es) layers are transient ionospheric phenomena that represent an important aspect of atmospheric dynamics, exerting influences on space weather and communication systems. They occur in the E region (~90-150 km) and are characterised by thin, localised layers of enhanced electron density. Their formation is linked to interactions involving atmospheric waves and tides, wind shear and/or electric field and plasma instabilities. Metal ions are tightly coupled with electrons through ionization and neutralisation processes and play a central role in the formation of Es layers1.

Recently, Wu et al. [2021]2 examined the full transport of three metal ions (Fe+, Mg+ and Na+) in the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X) - a self-consistent global model including their full neutral and ion-molecule chemistry and the injection of metals from meteoric ablation3,4. The work of Wu et al. [2021] significantly improved the modelled global distribution and seasonal dependence of the metal ions in WACCM-X; since it captures the complex interactions between numerous atmospheric components, this extended WACCM-X provides a useful framework for the study of Es layers on a global scale.

Although modelling of parameters relevant to Es layers (winds, temperatures, chemical constituents) has been carried out using whole atmosphere models2,5, modelling of Es layer occurrence has not been carried out self-consistently using a global climate model with metal ion transport. In this study we present a novel method to identify Es layers in WACCM-X with full transport of metal ions. We present a detailed account of the methodology employed for the identification of Es layers within WACCM-X and the resulting climatology of Es occurrence. The derived climatology is compared to observations from the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellite6, which provides global high-resolution ionospheric observations. This comparison enables us to evaluate the performance of the model and identifies potential areas for future development.

By better understanding the complex interplay between atmospheric variability and Es layer behaviour, we aim to improve our understanding of Es layers and their role in atmospheric dynamics. The insights gained from this research advance modelling capabilities, and could support space weather forecasting and communication systems, as well as contributing to the broader understanding of Es layers and their significance in atmospheric science.

 

1. Yu, B., et al. (2021) Atmospheric Chemistry and Physics, 21(5), 4219-4230

2. Wu, J., W. Feng, H. L. i. Liu, X. Xue, D. R. Marsh, and J. M. C. Plane (2021), Atmospheric Chemistry and Physics, 21(20), 15619-15630

3. Liu, H.-L., et al. (2018), Journal of Advances in Modelling Earth Systems, 10(2), 381-402

4. Carrillo-Sánchez, J. D., J. C. Gómez-Martín, D. L. Bones, D. Nesvorný, P. Pokorný, M. Benna, G. J. Flynn, and J. M. C. Plane (2020), Icarus, 335, 113395

5. Chu, Y. H., C. Y. Wang, K. H. Wu, K. T. Chen, K. J. Tzeng, C. L. Su, W. Feng, and J. M. C. Plane (2014), Journal of Geophysical Research: Space Physics, 119(3), 2117-2136

6. https://www.cosmic.ucar.edu/global-navigation-satellite-system-gnss-background/cosmic-1

How to cite: Aylett, T., Feng, W., Marsh, D. R., and Plane, J. M. C.: Modelling sporadic E (Es) layers in WACCM-X: Presenting a new methodology for the identification of Es layers, and the resulting climatology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5871, https://doi.org/10.5194/egusphere-egu24-5871, 2024.

EGU24-6177 | Posters on site | ST3.4

The Thermosphere and Ionosphere System Responses to Subauroral Polarization Streams (SAPS) During the March, 17, 2013 Geomagnetic Storm 

Wenbin Wang, Dong Ling, Slava Merkin, Qian Wu, and Yongliang Zhang

During geomagnetic storms, a latitudinally narrow band of strong sunward plasma drifts occurs just equatorward of auroral electron precipitation in the afternoon to pre-midnight sector, which is termed subauroral polarization steams (SAPS). SAPS are produced when the downward Region-2 current is closed through the subauroral region of low ionospheric conductivity and a strong poleward electric field is established to ensure current continuity. SAPS are a manifestation of the strong coupling between the magnetosphere and the ionosphere and thermosphere system. In this study, we employ the high-resolution Multiscale Atmosphere-Geospace Environment (MAGE) model that is developed by the NASA DRIVE Science Center for Geospace Storms (CGS) to simulate the SAPS effects on the global thermosphere-ionosphere system during the March 17 2013 geomagnetic storm. We compare two MAGE model runs, one with SAPS in the entire simulation and the other with the SAPS drifts being turned off when the ionospheric electric fields are used to calculate ion frictional heating, neutral Joule heating, ion drag and plasma transport. By comparing the results from these two runs we quantify the effects of SAPS on the thermosphere and ionosphere system. Our results show that with SAPS ionospheric total electron content (TEC) and electron densities are enhanced in the afternoon sector at middle and high latitudes. This provides a strong source of ionization for the high-latitude convection pattern to transport the plasma into the polar cap to form the polar tongue of ionization (TOI) and patches. Therefore, SAPS facilitate the occurrence and strengthening of TOI. The MAGE simulations also show that the phase and speed of storm-time traveling atmospheric disturbances and neutral circulation are modulated by the SAPS, and the SAPS effects are thus transmitted globally to affect the behavior of the entire thermosphere and ionosphere system during the storm.

How to cite: Wang, W., Ling, D., Merkin, S., Wu, Q., and Zhang, Y.: The Thermosphere and Ionosphere System Responses to Subauroral Polarization Streams (SAPS) During the March, 17, 2013 Geomagnetic Storm, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6177, https://doi.org/10.5194/egusphere-egu24-6177, 2024.

EGU24-6223 | ECS | Orals | ST3.4

Statistics of Small-Scale Ionospheric Waves in European Mid-Latitudes Observed Using LOFAR 

Ben Boyde, Alan Wood, Gareth Dorrian, Francesco de Gasperin, Frits Sweijen, Maaijke Mevius, and Kasia Beser

The LOw Frequency ARray (LOFAR) is a radio telescope centred in the Netherlands. The observed impact of the ionosphere on signals from astronomical radio sources can be used to derive differential Total Electron Content (dTEC) between the lines of sight from different LOFAR stations. The dTEC derived in calibration has extremely high precision (~1 mTECu) and is available at high temporal (~4s) and spatial (baselines from ~100 m to ~100 km) resolutions. These measurements provide a new means of studying ionospheric disturbances in the mid-latitudes.

A method for identifying wave signatures in the dTEC data has been developed and shown to be capable of identifying waves with amplitudes as low as a few mTECu (Boyde et al., 2023). This method has been used to analyse over 2,500 hours of observations made as part of an astronomical survey. The statistical characteristics of the identified waves and their dependence on time of day, season, and geomagnetic activity are discussed, such as variations in dominant propagation direction. These observations extend the range of ionospheric waves that can be identified to shorter wavelengths and lower amplitudes beyond what is currently detectable using GNSS derived TEC. This method complements established techniques for detecting ionospheric waves.

Ben Boyde, Alan George Wood, Gareth Dorrian, et al. Wavelet Analysis of Differential TEC Measurements Obtained Using LOFAR, Radio Science (Under Review), 2023, doi: 10.22541/essoar.169754969.93126117/v1

How to cite: Boyde, B., Wood, A., Dorrian, G., de Gasperin, F., Sweijen, F., Mevius, M., and Beser, K.: Statistics of Small-Scale Ionospheric Waves in European Mid-Latitudes Observed Using LOFAR, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6223, https://doi.org/10.5194/egusphere-egu24-6223, 2024.

EGU24-6700 | Orals | ST3.4

Thermosphere-ionosphere effects due to forcing from “above” and “below” as captured by TIEGCM-ICON 

Astrid Maute, Jeffrey Forbes, Chihoko Cullens, Brian Harding, and Thomas Immel

The lower to upper atmosphere vertical coupling via atmospheric solar tides is very variable and affects the dynamics, composition and electrodynamics of thermosphere-ionosphere (TI) system. In addition, complex solar wind forcing is always impacting the high latitude region and its effects can extend to the mid- and low latitude region.  The Ionospheric Connection (ICON) explorer mission provides almost 3 years of data and an opportunity to examine the variation in the TI due to lower atmospheric and MI forcing. This is facilitated by the ICON Level4 product, the thermosphere-ionosphere-electrodynamics general circulation model (TIEGCM) driven by tides fitted to ICON observations via the Hough Mode Extension (HME) method. The effects of the upward propagating tides can be isolated by examining the difference between two TIEGCM simulations with and without tidal HME forcing at the model’s lower boundary, while the effects of solar and magnetospheric variability can be estimated by the difference to a simulation with constant solar and geomagnetic forcing.

In this presentation we use over 2 years of TIEGCM simulations to evaluate the model by comparing primarily to ICON observations and examine the captured TI variations. A special focus in our comparison will be on the neutral wind and its two-way coupling to ion drift and plasma distribution. For specific time period we will delineate the contributions due to lower atmospheric tidal forcing from the one due to solar and magnetospheric forcing and quantify the separate effects on the neutral wind, ion drift, and plasma variation.

How to cite: Maute, A., Forbes, J., Cullens, C., Harding, B., and Immel, T.: Thermosphere-ionosphere effects due to forcing from “above” and “below” as captured by TIEGCM-ICON, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6700, https://doi.org/10.5194/egusphere-egu24-6700, 2024.

EGU24-7647 | Orals | ST3.4

Solar activity variations in the composition of the low- and mid-latitude ionosphere-thermosphere system 

Rajesh Vaishnav, Christoph Jacobi, Erik Schmölter, Hanna Dühnen, and Mihail Codrescu

Having a comprehensive understanding of the ionosphere's irregular behavior and its response to solar activity is crucial for satellite communication and navigation applications. The sun's extreme ultraviolet (EUV) and ultraviolet (UV) radiation are the primary sources of energy for the Earth's thermosphere and ionosphere (TI). To understand the global response of TI parameters (e.g., O/N2, and the peak electron density (Nmax)) to changes in solar irradiance, various data have been used. These include the Global-Scale Observations of the Limb and Disk (GOLD) ultraviolet imaging spectrograph, solar radio flux F10.7, predictions from the Coupled Thermosphere Ionosphere Plasmasphere electrodynamics (CTIPe) model, and International Global Navigation Satellite System Service total electron content maps (TEC). The comparison between these measurements shows that the CTIPe model successfully reproduces the behavior of the low- and mid-latitude ionosphere during both low and high solar activity.

The study also investigated the delayed ionospheric TEC response against solar flux variations within the 27-day solar modulation. It was observed that the delay is less than one day, which was also confirmed in model simulations. Furthermore, the model simulations showed that the ionospheric time delay is significantly affected by various physical processes such as diffusion, photodissociation, solar and geomagnetic activities, and wave dynamics.

How to cite: Vaishnav, R., Jacobi, C., Schmölter, E., Dühnen, H., and Codrescu, M.: Solar activity variations in the composition of the low- and mid-latitude ionosphere-thermosphere system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7647, https://doi.org/10.5194/egusphere-egu24-7647, 2024.

EGU24-7983 | Posters on site | ST3.4

Amplitudes of medium scale gravity waves (GWs) in the ionosphere 

Jan Rusz, Jaroslav Chum, and Jiří Baše

The amplitude of GWs increases with height due to the decrease in the density of the atmosphere, but at the same time the attenuation of the waves also increases with height due to the dissipation of energy through friction.

In this study, the propagation of GWs in the ionosphere is observed remotely, using multi-point, multi-frequency continuous HF Doppler sounding system situated in the western Czechia. The configuration of the system allows to determine not only the amplitude, but also the speed and direction of GWs propagation at different heights. An ionosonde located not far away from the Doppler sounding system is used to assign the reflection heights to individual measurements.

The amplitudes of medium-scale atmospheric gravity waves propagating in the ionosphere are measured and statistically processed to investigate the daily and annual variations, and their relation to the speed of the neutral winds and the measurement height. Results from periods of solar maximum and minimum are compared.

How to cite: Rusz, J., Chum, J., and Baše, J.: Amplitudes of medium scale gravity waves (GWs) in the ionosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7983, https://doi.org/10.5194/egusphere-egu24-7983, 2024.

EGU24-8387 | ECS | Orals | ST3.4

Higher-order Tides in the Variation of Post-sunset Meridional Winds and, consequently, OI 630.0 nm nightglow emissions over Low-latitudes 

Sovan Saha, Duggirala Pallamraju, Sunil Kumar, Fazlul I. Laskar, and Nicholas M. Pedatella

Airglow emissions act as a tracer of the altitudinal region of 100 km width centred around 250 km. Various dynamical processes such as neutral, electrodynamics, and atmospheric waves modulate the atmospheric parameters, such as temperature, density, etc., of the ionosphere-thermosphere system (ITS), which vary day-to-day, season, and solar flux as well. We have carried out investigations of ITS by measuring the OI 630.0 nm (redline) nightglow emissions over Gurushikhar, Mt. Abu (24.6°N, 72.7°E, 19°N Mag), a low-latitude location, using the High Throughput Imaging Echelle Spectrograph (HiTIES). On several occasions, a bell-shaped enhancement in these emissions has been noticed around 21 local time, following the typical monotonic decrement after sunset. The cause of this enhancement in redline emissions has been explored by investigating the equatorial electrodynamics and neutral winds. The meridional winds have been obtained by using two digisondes located at equatorial and low-latitude locations. Contrary to the conventional expectation of pre-reversal enhancement bringing additional plasma over the low-latitudes to cause such enhancement, the role of meridional winds has been demonstrated in our study. The poleward winds over the low-latitudes bring additional plasma down to the redline emission altitudes, resulting in the observed enhancement in emissions. The winds at these post-sunset hours are usually equatorward, and thus, this brings the question as to what is the cause for the reversal in wind during those times. We have analysed the winds, electron densities obtained from the global free-run model of Whole Atmosphere Community Climate Model with thermosphere-ionosphere eXtension (WACCM-X) data. It has been found that higher-order tides, such as quarter-diurnal tides, play an important role in causing a reversal in meridional winds from their usual equatorward to poleward direction. This clearly explains the root cause for the variation in meridional winds during the post-sunset hours as well as the reason why the post-sunset enhancements in OI 630.0 nm nightglow occur on one night and not the next, even though the electrodynamic forcing was similar on these two occasions. These new findings will be discussed.

How to cite: Saha, S., Pallamraju, D., Kumar, S., Laskar, F. I., and Pedatella, N. M.: Higher-order Tides in the Variation of Post-sunset Meridional Winds and, consequently, OI 630.0 nm nightglow emissions over Low-latitudes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8387, https://doi.org/10.5194/egusphere-egu24-8387, 2024.

EGU24-9005 | Posters on site | ST3.4

Analysis of MSTIDs triggered by dynamical events 

Dalia Buresova, Jaroslav Chum, Sivakandan Mani, Jens Mielich, Jaroslav Urbar, Veronika Barta, Anna Belehaki, Tobias G.W. Verhulst, David Altadill, Antoni Segara, Daniel Kouba, Marco Guerra, Petra Koucka Knizova, Zbysek Mosna, Kitti A. Berényi, Claudio Cesaroni, and Luca Spogli

It is well known that the ionosphere is a highly dynamic medium, and the electron density can vary significantly within a very short period of time at a given location. One of the reasons for the irregular variations are ionospheric signatures of Atmospheric Gravity Waves (AGWs) – Travelling Ionospheric Disturbances (TIDs). TIDs are one of the major and frequent wave-like perturbations of the ionospheric plasma. Medium scale TIDs (MSTIDs) have been described as perturbations characterized by a wavelength, period and phase speed of 50–500 km, 12–60 min and 50–400 m/s, respectively. The wave-like effects of the MSTIDs are one of the main obstacles for accurate interpolation of ionospheric corrections in a medium scale reference of the Global Positioning System (GPS) networks as the ionospheric delay is almost proportional to Total Electron Content (TEC) along the signal path and inversely proportional to the frequency squared. MSTIDs are a common phenomenon from high to low latitudes.

The main objective of the T-FORS project is the development of new validated models able to issue forecasts and alerts for TIDs several hours ahead, exploiting a broad range of observations of the solar corona, the interplanetary medium, the magnetosphere, the ionosphere and lower atmosphere. This paper presents our results on the analysis of dynamic events that trigger MSTIDs. The events identified for the purposes of the analysis were such as geomagnetic disturbances, deep tropospheric convections, earthquakes and volcano eruptions. Based on the T-FORS methodologies all available data (detrended TEC, Continuous Doppler Sounding System -CDSS measurements, Digisonde vertical and oblique soundings and gradients of the electron density, reference meteorological and seismic data) were used for this analysis. The MSTIDs occurrence was recorded and analysed and propagation pattern for these events were extracted and compared with the results of the climatological model. This comparison will support the definition of alerts criteria when the detected disturbances exceed the climatology. Physical conditions that triggered enhanced MSTID activity were also analysed to compile an inventory of parameters that can be considered as early indicators of enhanced MSTIDs.

How to cite: Buresova, D., Chum, J., Mani, S., Mielich, J., Urbar, J., Barta, V., Belehaki, A., Verhulst, T. G. W., Altadill, D., Segara, A., Kouba, D., Guerra, M., Koucka Knizova, P., Mosna, Z., Berényi, K. A., Cesaroni, C., and Spogli, L.: Analysis of MSTIDs triggered by dynamical events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9005, https://doi.org/10.5194/egusphere-egu24-9005, 2024.

EGU24-11018 | ECS | Posters on site | ST3.4

Ionospheric conductance due to electron and ion precipitations based on the comparison between EISCAT and DMSP estimates 

Xin Wang, Lei Cai, Anita Aikio, Heikki Vanhamäki, Ilkka Virtanen, Yongliang Zhang, Bingxian Luo, and Siqing Liu

Energetic particle precipitation is the major source of electron production that controls the ionospheric Pedersen and Hall conductances at high latitudes. Typically, the ionospheric conductances are estimated using either theoretical or empirical equations. The former method requires several ionospheric and thermospheric parameters as inputs. By contrast, empirical equations are simple, such as Robinson formulas and Galand formulas that have been widely used. In this study, we evaluate the empirical formulas of ionospheric conductances during four different types of auroral precipitation conditions based on 63 conjugate events observed by DMSP and EISCAT. The conductances calculated from the DMSP data with the empirical formulas are compared with those based on EISCAT measurements with the standard equations. The best correlation between these two is found when the empirical Robinson formulas are used in the presence of diffuse electron precipitation without ions. In the presence of ion precipitation, the correlation coefficients are smaller, but the correlation improves when the Galand formulas are used to estimate the contribution of ion precipitation to the conductances. For the condition of pure ion precipitation, the ionospheric conductances are increased up to 2-7 S for Pedersen and 2.5-10 S for Hall conductances. The increase is larger for a higher geomagnetic AE index. Overall, the empirical formulas applied to the DMSP particle spectra underestimate the ionospheric conductances.

How to cite: Wang, X., Cai, L., Aikio, A., Vanhamäki, H., Virtanen, I., Zhang, Y., Luo, B., and Liu, S.: Ionospheric conductance due to electron and ion precipitations based on the comparison between EISCAT and DMSP estimates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11018, https://doi.org/10.5194/egusphere-egu24-11018, 2024.

EGU24-11681 | ECS | Orals | ST3.4

The I-T response to most recent solar eclipses: Observations and modeling 

Sebastijan Mrak, Clayton Cantrall, Naomi Maruyama, Phil Chamberlin, Saurav Aryal, Yue Deng, and Marc Hairston

We discuss multiple observations of atmospheric dynamics during recent solar eclipses: 21 August 2017, 4 December 2021, 20 April 2023, 14 October 2023, and 8 April 2024. We use GOLD and TIMED/GUVI instruments to observe the changes in the lower thermosphere related to atmospheric oxygen O, and molecular nitrogen N2. We discuss the problematic nature of O/N2 composition estimation from brightnesses under solar obscuration conditions, and how the observations should be properly interpreted. The Ionosphere-Thermosphere (I-T) system responds to solar X-Ray and Extreme Ultra Violet (EUV) radiation, which is highly non-uniform during solar eclipses. We introduce a new model of solar eclipse obscuration and irradiance by combining the solar occultation software PyEclipse and Flare Irradiance Solar Model 2 (FISM2) -- FISM2-Eclipse. We implemented FISM2-Eclipse into the Global Ionosphere thermosphere Model (GITM) and Whole Atmosphere Model Ionosphere-Plasmasphere-Electrodynamics model (WAM-IPE) to conduct a model-data comparison. We discuss some salient features noted during the recent eclipses.

How to cite: Mrak, S., Cantrall, C., Maruyama, N., Chamberlin, P., Aryal, S., Deng, Y., and Hairston, M.: The I-T response to most recent solar eclipses: Observations and modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11681, https://doi.org/10.5194/egusphere-egu24-11681, 2024.

EGU24-12540 | Posters on site | ST3.4

Three-dimensional monitoring of Ionospheric storms using COSMIC-2 RO 

Lalit Mohan Joshi

High-rate Radio Occultation (RO) measurement using the COSMIC-2 constellation has enabled the observation of the transient changes in the ionosphere's three-dimensional (3D) structure.  This capability enables studying the changes to the 3D ionospheric structure during a geomagnetic storm. So far, the ionospheric storms (positive/negative ionospheric storms) that follow space weather events, have mostly been studied globally using two-dimensional (2D) TEC maps generated using ground-based networks. Ground-based networks also limit the measurements to only over the landmass and islands. High-rate 3D observation from COSMIC-2 can overcome these limitations of the ground-based networks. Such measurements provide 3D ionospheric variations over a large region lying within +/- 400 geographic latitude, with a spatiotemporal resolution significant enough to provide new insights.  This paper presents a 3D perspective of the ionospheric impact of the November 04, 2021, geomagnetic storm. In the present study, electron density has been binned with latitude, longitude, altitude, and time resolution of 60, 300, 25 km, and 2 hours, respectively. It must be noted that the present study excludes electron density variation below 225 km altitude where RO retrievals are not considered reliable. Some of the key observed features of the ionospheric storm under consideration are: (a) Large enhancement in the ionospheric plasma density due to the enhanced ‘fountain effect’ in the main phase is most significant in the topside ionosphere with a maximum variation observed above 450 km, (b) the most significant enhancement in the topside ionospheric plasma density (positive storm effect) was seen during the midnight period, irrespective of the longitude under consideration, (c) enhancement in the electron density also indicated some longitudinal dependence, and (d) most significant impact of the ionospheric storm was observed over the latitudinal belt lying beyond the poleward boundary of the EIA crests.  These and several other interesting observations will be presented. Results will also be discussed in light of the current understanding of ionospheric storms.

How to cite: Joshi, L. M.: Three-dimensional monitoring of Ionospheric storms using COSMIC-2 RO, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12540, https://doi.org/10.5194/egusphere-egu24-12540, 2024.

EGU24-13541 | Posters on site | ST3.4

Statistical correlations between geomagnetic activity and high-latitude TIDs investigated with the Tromso Dynasode 

Catalin Negrea, Nikolay Zabotin, Marius Echim, and Mike Rietveld

Travelling Ionospheric Disturbances (TID) and the underlying Atmospheric Gravity Waves (AGW) have long been associated with cases of extreme geomagnetic activity. This is especially true for geomagnetic storms that have been linked to large scale TIDs (LSTID). However, in the case of mid-scale TIDs (MSTID), a clear correlation has yet to be shown with geomagnetic activity, except for isolated cases. Such a correlation has been long suspected and assumed, since the mechanism by which these waves are generated must be linked to particle precipitation and localized heating, which occurs to some extent at all levels of geomagnetic activity due to the solar wind - magnetosphere - ionosphere coupling.

Our study used 7 years of measurements from the Tromso dynasonde, specifically the electron density and ionospheric tilts height profiles. These are generally available at a 2-minute cadence and thus can be used to resolve the bulk of the gravity wave spectrum. The excellent height resolution of the data, as well as the directionality of the two ionospheric tilts allow us to quantify the TID activity using an estimator based on the power spectral density integral. This proxy for overall TID activity accounts for all waves from all sources: auroral, orographic, from tropospheric weather, etc. We then demonstrate the relative importance of auroral waves by showing that TIDs with a north-south propagating direction correlate very well with geomagnetic indices indicative of geomagnetic disturbances at high-latitude (the AE, Kp and Polar Cap Indices), while less so for the SYM-H index, which is more indicative of lower latitudes. Long-term correlations are discussed, with an emphasis on changes to the statistical distribution describing the correlation. Finally, a high-precision analysis was performed to pin-point the time-delay between geomagnetic and TID activity at Tromso. The results show a dominant population of TIDs characterized by a delay of 2-6 hours, with a secondary population with delays larger than 10 hours.

How to cite: Negrea, C., Zabotin, N., Echim, M., and Rietveld, M.: Statistical correlations between geomagnetic activity and high-latitude TIDs investigated with the Tromso Dynasode, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13541, https://doi.org/10.5194/egusphere-egu24-13541, 2024.

The Geospace Dynamics Constellation (GDC) is NASA's next strategic Living With a Star mission. GDC's goals are: 1) Understand how the high-latitude ionosphere-thermosphere system responds to variable solar wind/magnetosphere forcing; and 2) Understand how internal processes in the global ionosphere-thermosphere system redistribute mass, momentum, and energy. Planned for launch by the end of the decade, GDC will use six identical observatories, each identically instrumented to fully characterize the magnetospheric drivers of the I-T system as well as the global response of the ionized and neutral gases. GDC will do this with a series of orbital configurations that will enable it to study the widest range of spatial and temporal scales to date, ranging from hundreds of kilometers and several seconds to tens of minutes, and extending through the regional to the global scale. This talk presents GDC's current status, measurement capabilities, sampling scheme, and model development efforts and show how GDC will fit into the larger Heliophysics ecosystem, by 1) obtaining critically needed scientific observations; 2) providing a source for real-time space weather and situational awareness, as well as retrospective studies to further the science of space weather; 3) serving as a "strategic hub" for other space-based and ground-based efforts that want to leverage GDC to perform complementary science.

To get the most benefit from GDC’s observations, it will be critical to identify partnerships with other research efforts in the ITM and Geospace arenas, including those utilizing space-based, ground-based, or theoretical investigations. We particularly would like to discuss with groups who are planning or considering observational campaigns during the GDC era, to find ways to leverage GDC observations to do synergistic science that could not be done otherwise.

How to cite: Kepko, L. and Rowland, D. and the GDC Instrument and IDS teams: NASA’s Geospace Dynamics Constellation—Providing the first Systematic Measurements of Global Magnetospheric Energy Inputs and Ionosphere-Thermosphere Responses, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13670, https://doi.org/10.5194/egusphere-egu24-13670, 2024.

EGU24-13772 | Posters on site | ST3.4

APEP: Eclipse Sounding Rocket Campaign 

Aroh Barjatya, Robert Clayton, Shantanab Debchoudhury, Matthew Zettergren, Henry Valentine, Nathan Graves, Rachel Conway, Peter Ribbens, Joshua Milford, Kenneth Obenberger, Jeffrey Holmes, Jorge (Koki) Chau, Kristina Lynch, Sebastijan Mrak, and Terry Bullett

Solar eclipses present a unique opportunity to study the effects of a supersonic cooling shadow and its modulation of the structure and energetics of the ionosphere-thermosphere system. Atmospheric Perturbations around Eclipse Path (APEP) is an eclipse rocket campaign that launched 3 sounding rockets from White Sands Missile Range (WSMR) during the Oct 2023 annular eclipse and will launch 3 sounding rockets from the Wallops Flight Facility (WFF) during the April 2024 total solar eclipse. This campaign will be the first simultaneous multipoint spatio-temporal in-situ observations of electrodynamics and neutral dynamics associated with solar eclipses. For each eclipse, the first instrumented rocket will be launched ~35 minutes before peak local eclipse, second at peak local eclipse, third ~35 minutes after peak local eclipse. The launches are supported by ground-based observations from AFRL Digisondes for WSMR launch and by VIPIR Dynasonde and Millstone ISR for WFF launch. Ground based meteor radar observations of neutral winds are also performed for both eclipses. These observations will be used to constrain comprehensive modeling during data analysis. 

How to cite: Barjatya, A., Clayton, R., Debchoudhury, S., Zettergren, M., Valentine, H., Graves, N., Conway, R., Ribbens, P., Milford, J., Obenberger, K., Holmes, J., Chau, J. (., Lynch, K., Mrak, S., and Bullett, T.: APEP: Eclipse Sounding Rocket Campaign, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13772, https://doi.org/10.5194/egusphere-egu24-13772, 2024.

EGU24-16449 | ECS | Orals | ST3.4

MATS satellite mission: Global patterns 

Björn Linder, Linda Megner, Donal Murtagh, Ole Martin Christensen, Jörg Gumbel, and Nickolay Ivchenko

MATS (Mesospheric Airglow/Aerosol Tomography and Spectroscopy) is a Swedish research satellite launched in 2022 targeting gravity wave activity in the mesosphere and lower thermosphere (MLT). Infrared measurements of MLT O2 A-band airglow conducted by the MATS satellite during February, March, and April reveal large-scale, global structures that significantly impact this region's dynamics. An analysis of atmospheric A-band emissions between 70 and 110 km reveals that atmospheric tides greatly influence the radiance produced in the airglow layer. This is evidenced by an equatorial maximum at local sunset and minima at 30°N and 30°S, which correspond to the various phases of the tides. Meanwhile - in the vicinity of the poles, westward propagating planetary waves dominate the measurements, including strong signals from the 16-day wave in the northern hemisphere, and the 5.5-day wave in the southern hemisphere. In this talk, we take a closer look at the individual measurements made by the satellite, illustrating the smaller-scale atmospheric structures they contain, as well as the global picture that the images make up together. 

How to cite: Linder, B., Megner, L., Murtagh, D., Christensen, O. M., Gumbel, J., and Ivchenko, N.: MATS satellite mission: Global patterns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16449, https://doi.org/10.5194/egusphere-egu24-16449, 2024.

EGU24-17824 | ECS | Posters on site | ST3.4

Contiguous Space-time TEC Enhancements in JPL GIMs - Seasonal, Latitudinal and Activity dependence 

Martin Cafolla, Sandra Chapman, Nick Watkins, Xing Meng, and Olga Verkhoglyadova

The variability of GPS positioning and timings impacts navigation, communication and other low-Earth orbit satellites and is affected by space weather. Ground GNSS observations of Total Electron Content (TEC) with 100 − 200 ground stations are used to compile global maps of TEC to monitor ionospheric response to space weather events. We consider Global Ionospheric Maps (GIMs) available at a 15-minute cadence and a spatial resolution of 1 × 1 degree longitide/latitude bins from the Jet Propulsion Laboratory (JPL). These are available over 2 solar cycles, providing an extensive data set covering both seasonal variation and quiet/active times. Our study uses feature extraction to identify regions of enhanced TEC that are contiguous in both space and time. For each map, we identify spatially contiguous High Density Regions (HDRs) as the region on the TEC map within which the level is exceeded by the top 1% of TEC values. We then apply a tracking algorithm over consecutive timestamps to obtain a set of labelled coherent space-time TEC HDRs. Extracting and following these HDRs over multiple years allows us to explore their statistical dependencies upon geomagnetic activity, latitude and season. Given a set of geomagnetic indices (Dst, Kp and/or F10.7) at some date-time, we can determine the locations of HDRs, how long they last and their size/brightness. Our analysis detects, labels and tracks HDR origin, path, areas, TEC intensities and duration. TEC estimation in the JPL data has higher accuracy over the continental US and Europe than in other areas. We consider how this non-uniform distribution of ground stations affect our results.

How to cite: Cafolla, M., Chapman, S., Watkins, N., Meng, X., and Verkhoglyadova, O.: Contiguous Space-time TEC Enhancements in JPL GIMs - Seasonal, Latitudinal and Activity dependence, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17824, https://doi.org/10.5194/egusphere-egu24-17824, 2024.

EGU24-18179 | ECS | Posters on site | ST3.4

Correlation of Magnetic Field Dynamics and Atmosphere for the study of the quasi six-year oscillation from Earth's core 

Guilhem Chicot, Véronique Dehant, and Olivier De Viron

Recent studies have identified a quasi six-year oscillation (QSYO) spanning various Earth system parameters, including the length of day, polar motion, secular variation of the magnetic field, sea level, precipitation, terrestrial water storage, land ice, and winds. This oscillation is linked to fluid dynamics processes in the liquid outer core, yet the mechanism facilitating its transmission from the core to the broader Earth system remains unclear. One of the proposed scenario is the plausible role of the magnetic field as a conduit for transmitting the QSYO from the core to the climatic system

Leveraging data from atmospheric and magnetic models alongside observations from Global Navigation Satellite System (GNSS), our approach employs statistical analysis to explore the presence of the QSYO in the atmosphere. We specifically analyze various parameters in both the charged (e.g., Total Electron Content - TEC) and neutral (e.g., nebulosities) atmospheric layers. This study aims to establish the existence of the QSYO in the atmosphere and link its variations with those from core in the magnetic field. 

How to cite: Chicot, G., Dehant, V., and De Viron, O.: Correlation of Magnetic Field Dynamics and Atmosphere for the study of the quasi six-year oscillation from Earth's core, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18179, https://doi.org/10.5194/egusphere-egu24-18179, 2024.

EGU24-19953 | ECS | Posters on site | ST3.4

Evaluation of the mid-latitude ionospheric trough using high-resolution IGS ionospheric maps 

Kateryna Lubyk, Mohammed Mainul Hoque, Claudia Stolle, and Andreas Wehrenpfennig

The ionospheric mid-latitude trough is a phenomenon which is characterized through an electron density depletion in the F-layer of the ionosphere at the sub-auroral zone. In this study, we identify and derive the mid-latitude ionospheric trough properties using high-resolution Global Ionospheric Maps (GIMs) from International GNSS Service (IGS), namely UQRG maps, which have a high temporal resolution of 15 minutes. Our study is based on an extensive database, which we obtained by detecting troughs between 1998 and 2022, including two complete solar cycles (23 and 24). We have analyzed essential factors that define the MIT, like the trough minimum position, width, depth, and occurrence probability. All these MIT parameters represent morphological characteristics of the midlatitude trough in dependence on the magnetic local time, geographic distribution, seasons, and solar and geomagnetic activity conditions, including solar wind plasma speed, interplanetary magnetic field components, and geomagnetic activity indices SYM-H and Hp30.

Since the MIT climatology and occurrence probability have not yet been included in widely used 3D electron density models like IRI, NeQuick, NEDM2020, etc., the discovered dependencies can be used to validate current MIT models and to develop new MIT models. The performance of the 3D electron density models might be enhanced by including an MIT model.

How to cite: Lubyk, K., Hoque, M. M., Stolle, C., and Wehrenpfennig, A.: Evaluation of the mid-latitude ionospheric trough using high-resolution IGS ionospheric maps, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19953, https://doi.org/10.5194/egusphere-egu24-19953, 2024.

ST4 – Space Weather and Space Climate

We combine the electromagnetic fields from a hybrid plasma model with a particle tracing tool to study the spatial distribution of energetic neutral atoms (ENAs) emitted from Titan's atmosphere when the moon is exposed to different magnetospheric upstream regimes. These ENAs are generated when energetic magnetospheric ions undergo charge exchange within Titan's atmosphere. The spatial distribution of the emitted ENA flux is largely determined by the parent ions' trajectories through the draped fields in Titan's interaction region. Since images from the ENA detector aboard Cassini captured only a fraction of the ENA population, we provide context for such observations by calculating maps of the ENA flux through a spherical detector concentric with Titan. We determine the global distribution of ENA emissions and constrain deviations between the locations of ENA production and detection. We find that the ENA flux is highest in a band that encircles Titan perpendicular to the ambient magnetospheric field, which was strictly perpendicular to the moon's orbital plane during only one Cassini flyby. The field line draping strongly attenuates the emitted ENA flux, but does not alter the overall morphology of the detectable flux pattern. The majority of detectable ENAs leave Titan's atmosphere far from where they are produced, that is, even a spacecraft located directly above the moon's atmosphere would detect ENAs generated beyond its immediate environment. Some energetic parent ions produce ENAs only after they are mirrored by the field perturbations in Titan's wake and return to the moon, demonstrating the complex histories of detectable ENAs.

How to cite: Simon, S., Tippens, T., and Liuzzo, L.: Influence of Titan's Variable Electromagnetic Environment on the Global Distribution of Energetic Neutral Atoms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6, https://doi.org/10.5194/egusphere-egu24-6, 2024.

EGU24-1237 | ECS | Orals | PS4.2

Steady-state of the Martian induced magnetosphere and its rapid response to interplanetary magnetic field rotation 

Rentong Lin, Shiyong Huang, Zhigang Yuan, Honghong Wu, Kui Jiang, Yuming Wang, Tielong Zhang, Sibo Xu, Yue Dong, Qiyang Xiong, and Huxing Huang

The induced magnetosphere in non-magnetized planets or moons, formed by the interaction between their atmosphere and stellar wind or planetary wind, is generally modulated by external magnetic field.

 

The magnetic field in the induced magnetosphere is believed to be dominated by the draped field. The direction of such draped field is theoretically expected to align with the y-z direction of the interplanetary magnetic field. However, observations show the opposite direction of magnetic field in the induced magnetospheres from the interplanetary magnetic field direction. Using joint observations from Tianwen-1 and MAVEN, we obtain the averaged magnetic field map of the Martian induced magnetosphere in the accurate MSE coordinate system and calculated its standard deviation. The standard deviation confirms that the averaged magnetic field distribution is consistent with the steady state assumption. The magnetic field map illustrates a clockwise rotation of the averaged magnetic field in the y-z plane, occurring in both the dayside and nightside in the Martian induced magnetosphere. According to the magnetic induction equation, this clockwise rotation of the magnetic field occurs when a difference in the speed of plasma flow exists within the magnetosphere. It should be noted that the induced magnetospheres of the other non-magnetized planets exhibit similar qualitative properties to that of Mars, suggesting that they share comparable magnetic field characteristics.

 

Observations of the response process of induced magnetosphere to external magnetic field are significant for understanding global dynamical processes in non-magnetized planets, and yet such observations are quite scarce. Using simultaneous observations from Tianwen-1 and Mars Atmosphere and Volatile EvolutioN (MAVEN), we report for the first time the dynamic response of the Martian induced magnetosphere to the rotation of interplanetary magnetic field from the Sun. The magnetic field in the Martian induced magnetosphere deflected as the interplanetary magnetic field rotated suddenly, and eventually stabilized (< 3.5 minutes). The convective electric field rotated in response to the interplanetary magnetic field rotation, and the pick-up oxygen ion plume emerged in minutes (< 3 minutes). These quite short recovery timescales indicate that the induced magnetosphere is a rapidly dynamic system, and is highly sensitive to external magnetic field. It cautions us that change of interplanetary magnetic field should be considered as one of the general types of space weather on Mars, and it is essential of monitoring and short-term forecasting of interplanetary magnetic field upstream of Mars.

How to cite: Lin, R., Huang, S., Yuan, Z., Wu, H., Jiang, K., Wang, Y., Zhang, T., Xu, S., Dong, Y., Xiong, Q., and Huang, H.: Steady-state of the Martian induced magnetosphere and its rapid response to interplanetary magnetic field rotation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1237, https://doi.org/10.5194/egusphere-egu24-1237, 2024.

EGU24-1710 | ECS | Orals | PS4.2

Characterizing the current systems in the Martian ionosphere 

Jiawei Gao, Anna Mittelholz, Zhaojin Rong, moa persson, Zhen Shi, Chi Zhang, Xiaodong Wang, and Yong Wei

When the solar wind encounters the ionosphere of an unmagnetized planet, it induces currents, forming an induced magnetosphere. These currents, along with their associated magnetic fields, play a crucial role in controlling the movement of charged particles, and are essential for understanding the escape of planetary ions. Unlike the well-documented magnetospheric current systems, the ionospheric current systems on unmagnetized planet remain less understood, limiting our ability to quantify electrodynamic energy transfer. Here, using 8 years of data from the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, we provide the first global map of the Martian ionospheric currents. We identified two current systems coexist within the ionosphere: one aligning with the solar wind electric field, with asymmetries between the west-east electric hemispheres and driven by the solar wind; and one characterized by two current vortices on the dayside, powered by the atmospheric neutral winds. Our findings indicate that the Martian ionospheric dynamics are influenced by both the neutral winds from below and the solar wind from above, emphasizing the intricate nature of current systems on unmagnetized planets.

How to cite: Gao, J., Mittelholz, A., Rong, Z., persson, M., Shi, Z., Zhang, C., Wang, X., and Wei, Y.: Characterizing the current systems in the Martian ionosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1710, https://doi.org/10.5194/egusphere-egu24-1710, 2024.

EGU24-2228 | ECS | Orals | PS4.2 | Highlight

Observations of a Mini-Magnetosphere Above the Martian Crustal Magnetic Fields 

Kai Fan, Yong Wei, Markus Fraenz, Jun Cui, Fei He, Limei Yan, Lihui Chai, Jun Zhong, Zhaojin Rong, and Eduard Dubinin

Mars is typically regarded as a non-magnetic planet. Currents in the Martian ionosphere generate a Venus-like induced magnetosphere which deflects the solar wind flows and piles up the interplanetary magnetic fields. However, crustal magnetic fields in the southern hemisphere influence local plasma properties. Using observations from the MAVEN mission, we characterize the distinguishing plasma characteristics of a mini-magnetosphere that forms on the Martian dayside. We establish three criteria to differentiate this mini-magnetosphere from the induced magnetosphere. Notably, the mini-magnetosphere exhibits higher plasma beta (values near 1), with a balance between planetary ions, crustal magnetic fields, and the solar wind at the magnetopause. Observations show that the crustal magnetosphere reaches an altitude of 1,300 km, larger than one-third of the Martian radius, indicating a dichotomy between the induced northern and the crustal southern magnetospheres. These findings offer novel insights into the distinctive properties of hybrid magnetospheres in the near-Mars space.

How to cite: Fan, K., Wei, Y., Fraenz, M., Cui, J., He, F., Yan, L., Chai, L., Zhong, J., Rong, Z., and Dubinin, E.: Observations of a Mini-Magnetosphere Above the Martian Crustal Magnetic Fields, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2228, https://doi.org/10.5194/egusphere-egu24-2228, 2024.

EGU24-2891 | ECS | Orals | PS4.2

The response of Martian photoelectron boundary to the 2018 global dust storm 

Yuqi Wang, Yong Wei, and Kai Fan

Extensive research efforts have revealed that the Martian dust storms can perturb the upper atmospheric condition and as a consequence, enhance plasma density and photoelectron flux in the ionosphere. However, previous observational studies of the Martian dust storm impacts have been restricted to regions below 400 km, which limits our understanding of the Martian dust storm effects in the upper ionosphere and magnetosphere. Here, based on the suprathermal electron measurements made by the Solar Wind Electron Analyzer onboard the Mars Atmosphere and Volatile Evolution, we identify with an automatic procedure the occurrences of all photoelectron boundary (PEB) crossings at solar zenith angle below 120° (with a dust-free median altitude of about 600 km). Using the dayside PEB as a proxy of the upper ionospheric and magnetospheric condition, we analyze the variations of the PEB altitude during the 2018 global dust storm (GDS) of Mars Year 34 (MY34) and compare them with the period in MY33 when there was no global dust storm. We conclude that the column dust optical depth (CDOD) emerges as one of the main driving factors for PEB altitude variations during the GDS. Our analysis implies that the GDS can affect the Martian upper atmosphere and ionosphere over considerable distances and extended time scales.

How to cite: Wang, Y., Wei, Y., and Fan, K.: The response of Martian photoelectron boundary to the 2018 global dust storm, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2891, https://doi.org/10.5194/egusphere-egu24-2891, 2024.

EGU24-2924 | ECS | Orals | PS4.2

Solar and solar wind energy drivers for O+ and O2+ ion escape at Mars 

Neesha Schnepf, Yaxue Dong, David Brain, Gwen Hanley, William Peterson, Robert Strangeway, Ed Thiemann, Jasper Halekas, Jared Espley, Frank Eparvier, and James McFadden

Mars once had a dense atmosphere enabling liquid water existing on its surface, however, much of that atmosphere has since escaped to space. We examine how incoming solar and solar wind energy fluxes drive escape of atomic and molecular oxygen ions (O+ and O2+) at Mars. We use MAVEN data to evaluate ion escape from February 1, 2016 through May 25, 2022. We find that Martian O+ and O2+ have increased escape flux with increased solar wind kinetic energy flux. Increased solar wind electromagnetic energy flux also corresponds to increased O+ and O2+ escape flux. Increased solar irradiance (both total and ionizing) does not obviously increase escape of O+ and O2+. Together, these results suggest that the solar wind electromagnetic energy flux should be considered along with the kinetic energy flux, and that other parameters should be considered when evaluating solar irradiance’s impact on O+ and O2+ escape.

How to cite: Schnepf, N., Dong, Y., Brain, D., Hanley, G., Peterson, W., Strangeway, R., Thiemann, E., Halekas, J., Espley, J., Eparvier, F., and McFadden, J.: Solar and solar wind energy drivers for O+ and O2+ ion escape at Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2924, https://doi.org/10.5194/egusphere-egu24-2924, 2024.

EGU24-3755 | ECS | Posters on site | PS4.2

Effects of solar wind density and velocity variations on the Martian ionosphere and plasma transport 

Yihui Song, Haoyu Lu, Jinbin Cao, Xiaoshu Wu, Yang Liu, Shibang Li, Siqi Wang, James A. Wild, Chenling Zhou, Jianxuan Wang, and Nihan Chen

Solar wind dynamic pressure, consisting solar wind density and velocity, is an important external driver that controls Martian plasma environment. In this study, a 3D magnetohydrodynamic model is applied to investigate the separate influences of solar wind density and velocity on the Martian ionosphere. The spatial distributions of ions in the dayside and near nightside ionosphere under different solar wind density and velocity conditions are analyzed, as well as the ion transport process. We find that for the same dynamic pressure condition, the ionosphere extends to higher altitudes under higher solar wind density, indicating that a solar wind velocity enhancement event is more efficient at compressing the Martian ionosphere. A higher solar wind velocity will result in a stronger induced magnetic field, shielding the Martian ionosphere, preventing the penetration of solar wind particles. For the same dynamic pressure, increasing solar wind density (decreasing velocity) leads to a higher horizontal ion velocity, facilitating day-to-night plasma transport. As a result, the ionosphere extends farther into the nightside. Also, the ion outflow flux is larger for high solar wind density, which may lead to a higher escape rate. Moreover, the strong crustal fields in the southern hemisphere also cause significant effect to the ionosphere, hindering horizontal ion transport. An additional outflow channel is also provided by the crustal field on the southern dayside, causing different responses of flow pattern between local and global scale while the solar wind condition is varied.

How to cite: Song, Y., Lu, H., Cao, J., Wu, X., Liu, Y., Li, S., Wang, S., Wild, J. A., Zhou, C., Wang, J., and Chen, N.: Effects of solar wind density and velocity variations on the Martian ionosphere and plasma transport, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3755, https://doi.org/10.5194/egusphere-egu24-3755, 2024.

EGU24-4015 | Orals | PS4.2 | Highlight

Tianwen-1 MINPA in-flight operation and first science results 

Wenya Li, Linggao Kong, and Jijie Ma

The Mars Ion and Neutral Particle Analyzer (MINPA), one of the seven scientific payloads onboard the Tianwen-1 orbiter, was specifically designed to investigate the interaction between the solar wind and Mars by analyzing ions and energetic neutral atoms (ENAs). Commencing its scientific data collection in November 2021, MINPA successfully completed its first far-magnetotail survey during the summer of 2022. Our presentation will provide a comprehensive overview of MINPA's in-flight operations and its initial scientific findings. Regarding ENA observations, MINPA achieved successful data collection during solar wind, magnetosheath, and nightside observations. An algorithm has been developed to convert ENA count rates into intensity. A statistical analysis of solar wind ENAs revealed a neutralization rate of the solar wind at the flanks of the Mars magnetosphere. We also performed a collaborative analysis using MINPA data and numerical modeling to gain a deeper understanding of the ENA spectrum and its properties. In the ion component, MINPA observed hydrogen and heavy ions across various regions at Mars. With a far apoapsis, MINPA measured heavy ion escape in the far magnetotail, showcasing significant enhancements during periods of coronal mass ejection (CME) impacts. To enhance our understanding of the Martian space environment, an interdisciplinary team, comprising scientists from the Tianwen-1, Emirates Mars Mission (EMM), Mars Atmosphere and Volatile Evolution (MAVEN), and Mars Express missions, has been assembled within the ISSI framework.

How to cite: Li, W., Kong, L., and Ma, J.: Tianwen-1 MINPA in-flight operation and first science results, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4015, https://doi.org/10.5194/egusphere-egu24-4015, 2024.

A three-dimensional, four-species multi-fluid magnetohydrodynamic (MHD) model was developed to simulate the global interaction between the solar wind and Venus during the solar maximum and solar minimum periods. The model was augmented to incorporate the production and loss of the significant ion species in the Venusian ionosphere, i. e. H+, O2+, O+, CO2+, taking into account chemical reactions among all species. Results of simulated Venusian induced magnetosphere, which were validated by comparing with the observations from Venus Express, suggest that the shock locations are closer to the planet during the solar minimum condition, because the magnitude of electromagnetic forces in the minimum increased to counterbalance the heightened solar wind dynamic pressure. The Venusian ionosphere simulation results show that the ionospheric density profile is more condensed during solar minimum which are consistent with previous observations and simulations. Moreover, by taking advantage of our model, functions of electromagnetic forces acting on various ion species were analyzed to explore potential mechanisms behind the differences between these two solar wind conditions. The estimated ions escape rate is much higher for the minimum condition due to increased J×B forces within the magnetotail which are cause by the compressed magnetic field lines under higher solar wind dynamic pressures. This multi-fluid MHD model could serve as an efficient tool for exploring the fine structures of the Venusian space environment system and could also find applications in the future study of distinguishing impacts caused by the variation of a single parameter.

How to cite: Chen, N., Lu, H., and Li, S.: Solar Wind - Venus Interaction During the Solar Maximum & Solar Minimum Periods: A Newly Developed Multi-Fluid MHD Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4026, https://doi.org/10.5194/egusphere-egu24-4026, 2024.

EGU24-4227 | ECS | Orals | PS4.2

The Impact and Mechanism of Magnetic Fields on Plasma Dynamics in the Martian Space Environment 

Shibang Li, Haoyu Lu, Jinbin Cao, Jun Cui, Nihan Chen, Yihui Song, and Jianxuan Wang

The absence of a global magnetic field at Mars results in a direct interaction between the solar wind and the ionosphere, leading to ion escape from its atmosphere to space. However, the existence and asymmetric distribution of crustal fields introduce significant complexity into the plasma dynamics within the Martian environment, resulting from a disordered magnetic field topology characterized by its orientation parallel, directed towards, and away from the Martian surface. Based on three-dimensional multifluid magnetohydrodynamic simulations, we investigated the impact of the magnetic inclination angle on the Martian ionospheric plasma dynamics under the typical solar wind conditions. Numerical results showed that ions can be effectively diffuse upwards along vertical magnetic fields driven by the electron pressure gradient and the motional electric force, leading to a strong outward flux escaped through plume and the magnetotail eventually. In addition, due to the Hall electric force, there is a tendency for ion flow to be deflected in the horizontal plane. These results provide valuable insights into the influence of magnetic fields on ion motion in the Martian space environment.

How to cite: Li, S., Lu, H., Cao, J., Cui, J., Chen, N., Song, Y., and Wang, J.: The Impact and Mechanism of Magnetic Fields on Plasma Dynamics in the Martian Space Environment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4227, https://doi.org/10.5194/egusphere-egu24-4227, 2024.

Using global magnetohydrodynamics simulations, we investigate the effects of the solar wind magnetosonic Mach number and the interplanetary magnetic field (IMF) on the bow shock of Venus.  Our results reveal the following findings:  (1) The size of the Venusian bow shock is primarily determined by Mach number. An increase in Mach number results in the bow shock moving closer to Venus and a reduction in its flaring angle. (2) Both the subsolar standoff distance and the bow shock's flaring angle increase with the strength of the IMF components that are perpendicular to the solar wind flow direction (By and Bz in the VSO coordinate system), whereas the parallel IMF component (Bx) has a limited impact on the subsolar standoff distance but affects the flaring angle. (3) The cross-section of the bow shock is elongated in the direction perpendicular to the IMF on the Y-Z plane, and the elongation degree is enhanced with increasing intensities of By and Bz. (4) The quasi-parallel bow shock locates closer to the planet as compared to the quasi-perpendicular bow shock. These findings are in alignment with prior empirical and theoretical models. The influences of Mach number and IMF on the bow shock's position and geometry are attributed to the propagation of fast magnetosonic waves, showing the nature of the formation of a collisionless bow shock under the interaction of magnetized flow with an atmospheric object.

How to cite: Xu, Q.: The effects of Mach number and IMF on the location of Venus bow shock: an MHD study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4901, https://doi.org/10.5194/egusphere-egu24-4901, 2024.

EGU24-5382 | Posters virtual | PS4.2

MAVEN Observations of the Interloop Magnetic Reconnections at Mars 

Guo Chen, Can Huang, Ying Zhang, Yasong Ge, Aimin Du, Rongsheng Wang, Lei Wang, Lican Shan, Christian Mazelle, and Hao Luo

Magnetic reconnection between neighboring magnetic field loops, so-called inter-loop reconnection, is a common process to drive flares in the solar atmosphere. However, there is no direct evidence that a similar but less explosive process can take place on planets. The strong crustal fields on Mars are capable of generating plenty of magnetic loops in the near Mars regions, which provides a unique environment to research the inter-loop reconnection on a planet. Here, we report magnetic reconnection events between crustal field loops in the Martian ionosphere observed by MAVEN for the first time. During the current layer crossing, signatures including Hall magnetic field, Alfvénic outflow, and electron energization were recorded, and the energized electrons exhibited auroral-like peaked electron distributions. This finding implies that the inter-loop reconnection in the Martian ionosphere could contribute to the localized energy deposition and particle energization, which provides the seed source for aurora in the Martian atmosphere.

How to cite: Chen, G., Huang, C., Zhang, Y., Ge, Y., Du, A., Wang, R., Wang, L., Shan, L., Mazelle, C., and Luo, H.: MAVEN Observations of the Interloop Magnetic Reconnections at Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5382, https://doi.org/10.5194/egusphere-egu24-5382, 2024.

EGU24-5481 | ECS | Orals | PS4.2

Constraining ion transport in the diamagnetic cavity of comet 67P 

Zoe Lewis, Arnaud Beth, Marina Galand, Pierre Henri, Martin Rubin, and Peter Stephenson

Comets are small icy bodies originating from the outer solar system that produce an increasingly dense gas coma through sublimation as they approach perihelion. Photoionisation of this gas results in a cometary ionosphere, which interacts with the impinging solar wind, leading to large scale plasma structures. One such structure is the diamagnetic cavity: the magnetic field-free inner region that the solar wind cannot penetrate. This region was encountered many times by the ESA Rosetta mission, which escorted comet 67P/Churyumov-Gerasimenko for a two-year section of its orbit.

Within the diamagnetic cavity, high ion bulk velocities have been observed by the Rosetta Plasma Consortium (RPC) instruments. The fast ions are thought to have been accelerated by an ambipolar electric field, but the nature and strength of this field are difficult to determine analytically. Our study therefore aims to model the impact of various electric field profiles on the ionospheric density profile and ion composition. The 1D numerical model we have developed includes three key ion species (H2O+, H3O+, and NH4+) in order to assess the sensitivity of each to the timescale of plasma loss through transport. NH4+ is of particular interest, as it has been previously shown to be the dominant ion species at low cometocentric distances near perihelion. It is only produced through the protonation of NH3, a minor component of the neutral gas, and we show that this makes it particularly sensitive to the electric field.

We also compare the simulated electron density to RPC datasets, to find the electric field strength and profile which best recreate the plasma densities measured inside the diamagnetic cavity near perihelion. From this, we also constrain the radial bulk ion speed that is required to explain the observations with the model.

How to cite: Lewis, Z., Beth, A., Galand, M., Henri, P., Rubin, M., and Stephenson, P.: Constraining ion transport in the diamagnetic cavity of comet 67P, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5481, https://doi.org/10.5194/egusphere-egu24-5481, 2024.

Based on magnetic field and plasma measurements from the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, we present the first observation of magnetic reconnection occurring between the closed crustal magnetic field and the Ion Composition Boundry(ICB) at the dayside of Mars. Notably, distinctive typical features typical of reconnection, such as the Hall magnetic field and plasma outflow, have been unambiguously detected. Our findings robustly support the occurrence of reconnection at Mars, specifically highlighting the interaction between the interplanetary magnetic field in the induced magnetosphere and the closed crustal magnetic field. This reconnection event induces significant alterations in the magnetic field topology, exerting a profound influence on the escape dynamics of ions.

How to cite: Qiu, X. and Yu, Y.: Observations of magnetic reconnection between the crustal magnetic field and the ICB at Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5676, https://doi.org/10.5194/egusphere-egu24-5676, 2024.

EGU24-6135 | Orals | PS4.2

Interaction between non-linear plasma structures and collisionless shocks: magnetic holes vs cometary shock 

Cyril Simon Wedlund, Francesco Pucci, Luis Preisser, Pierre Henri, Etienne Behar, Giulio Ballerini, Francesco Califano, Thierry Passot, Pierre-Louis Sulem, and Adriana Settino

Linear Magnetic Holes (LMHs) are magnetic field depressions generated in the solar wind upstream of planetary and cometary shock. Some of those structures are reminiscent of mirror modes, thus possibly linked to the mirror mode instability driven by a temperature anisotropy in a large plasma beta environment. LMHs have also been found downstream of the shock, which suggests that they can survive its crossing (Karlsson et al. 2022). Using the new GPU-intensive kinetic hybrid model Menura (Behar et al. 2022), we present two-dimensional (2D 3V) simulations of individual solar-wind LMHs impacting a shock in quasi-perpendicular conditions. First, we feed an analytical model of stable LMHs of various size and depth with magnetic field and density variations in antiphase, oriented along the solar wind magnetic field, into the simulation. The LMHs are then left to propagate with and into the plasma flow, eventually impacting the shock, where they may cross into the induced magnetosheath. We look at the global and local effects of such crossings and how the structures' characteristics and their immediate vicinity change over time. We apply this setup to (i) a local quasi-perpendicular shock structure created by one reflecting boundary and (ii) a global simulation of a cometary environment, and compare with observational findings. This work is part of preliminary modelling efforts preparing for the upcoming ESA/JAXA Comet Interceptor mission.

How to cite: Simon Wedlund, C., Pucci, F., Preisser, L., Henri, P., Behar, E., Ballerini, G., Califano, F., Passot, T., Sulem, P.-L., and Settino, A.: Interaction between non-linear plasma structures and collisionless shocks: magnetic holes vs cometary shock, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6135, https://doi.org/10.5194/egusphere-egu24-6135, 2024.

EGU24-7269 | ECS | Posters on site | PS4.2

Solar Wind Energetic Neutral Atom Observation at Mars by MINPA Onboard the Tianwen-1 Orbiter 

Jijie Ma, Wenya Li, Linggao Kong, André Galli, Peter Wurz, Binbin Tang, Yiteng Zhang, Lianghai Xie, Limin Wang, and Fuhao Qiao

The Mars Ion and Neutral Particle Analyzer (MINPA), one of the seven scientific payloads onboard the Tianwen-1 orbiter, was designed to measure ions and energetic neutral atoms (ENAs) at Mars. Here, we present MINPA's first results of the solar-wind ENAs, which are produced through the charge exchange process between the solar wind hydrogen ions and the neutral atoms of the Martian exosphere. We perform a comprehensive comparison between the inflight ENA data and ground calibration results to understand the energy and angular distributions of the solar-wind ENA signals by MINPA, and an algorithm is developed to convert the ENA count rate to intensity. The contamination by solar extreme ultraviolet (EUV) and the observation independency between ENAs and ions are both evaluated. We will present several cases and statistic results of the solar wind ENA observations, and their intensities are estimated to be 10^5~10^6 cm^-2 sr^-1 s^-1, which is in good agreement with previous model attempts.

How to cite: Ma, J., Li, W., Kong, L., Galli, A., Wurz, P., Tang, B., Zhang, Y., Xie, L., Wang, L., and Qiao, F.: Solar Wind Energetic Neutral Atom Observation at Mars by MINPA Onboard the Tianwen-1 Orbiter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7269, https://doi.org/10.5194/egusphere-egu24-7269, 2024.

EGU24-7998 | ECS | Orals | PS4.2

Ion chemistry in the Martian dayside ionosphere 

Moa Persson and Erik Vigren

The ion composition of the Martian ionosphere is controlled by the ionisation of the neutral species (mainly CO2, CO and O) in the upper atmosphere and the chemical reactions that follow. The primary ions, CO2+ and O+, are reactive with O and CO2, respectively, as to produce O2+, which is the dominant ion species in the ionosphere. We apply a variety of simple chemical schemes to model the ion chemistry in the Martian dayside ionosphere using data from deep dip campaigns of the MAVEN mission. As model input we use concentrations of neutral species, as measured by the Neutral and Gas Ion Mass Spectrometer (NGIMS) onboard MAVEN, and solar EUV spectra measured by TIMED/SEE; extrapolated in distance and phase to Mars. We reach an adequate agreement between the calculated ion densities of the main ion species and those measured by NGIMS. However, the calculated ion composition does not fully match the measurements and deviations of up to a factor of 3-4 do prevail for some of the considered ion species. Several previous studies have solved similar issues by adjusting the input parameters to the calculations, such as increasing the neutral O density, reducing the neutral CO2 density or decreasing the solar irradiance. We present results from a thorough exploration of the involved parameter space and discuss possible reasons for still persisting model-observation discrepancies.

How to cite: Persson, M. and Vigren, E.: Ion chemistry in the Martian dayside ionosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7998, https://doi.org/10.5194/egusphere-egu24-7998, 2024.

EGU24-9328 | ECS | Posters on site | PS4.2

Study of Martian Ionospheric Plasma Depletion Events using MAVEN and Mars Express Spacecraft 

Praveen Basuvaraj, František Němec, Christopher Fowler, Leonardo Regoli, Zdeněk Němeček, and Jana Šafránková

Plasma Depletion Events (PDEs), characterized by a significant reduction (at least tenfold) in ion number density, are known to occur in the Martian ionosphere. Since its launch in September 2014, the MAVEN spacecraft has spotted around 1000 PDEs, primarily located in the nightside ionosphere and regions with strong crustal magnetic fields. We show that dayside PDEs are associated with an increased level of electrostatic fluctuations and suggest their formation through ambipolar diffusion triggered by the sudden escape of suprathermal electrons. We further investigate possible concurrent detections of PDEs by MAVEN and Mars Express. For this purpose, local electron density measurements from Mars Express near the MAVEN-identified PDEs are systematically checked. We present the first multi-spacecraft observations of PDEs, and we use them to discuss their spatio-temporal extents.

How to cite: Basuvaraj, P., Němec, F., Fowler, C., Regoli, L., Němeček, Z., and Šafránková, J.: Study of Martian Ionospheric Plasma Depletion Events using MAVEN and Mars Express Spacecraft, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9328, https://doi.org/10.5194/egusphere-egu24-9328, 2024.

EGU24-10518 | Orals | PS4.2

The Martian Surface Radiation Environment: Zenith Angle Dependence of Fluxes of Different Secondary Particle Species Produced in the Mars Atmosphere 

Salman Khaksarighiri, Robert F. Wimmer-Schweingruber, Timothy J. stubbs, Phillip H. Phipps, Mark D. Looper, Jingnan Guo, Bent Ehresmann, Donald M. Hassler, Daniel Matthiä, Cary Zeitlin, Jan Leo Löwe, Thomas Berger, Sven Löffler, and Günther Reitz

Understanding the zenith angle dependence of the Martian surface radiation environment is crucial for planning future human exploration missions to Mars. In our previous research (Wimmer et al. 2015; Guo et al. 2021; Khaksarighiri et al. 2023) we extensively studied the zenith-angle dependence of the Martian surface radiation dose rate. Leveraging the same validated radiation model, calibrated with data from the Radiation Assessment Detector (RAD) on Mars, we calculated the flux of secondary downward particles reaching to the surface of Mars from various zenith angles resulting from the interaction of primary particles with the Martian atmosphere. 

These flux of secondary particles, coming from different zenith angles, can be integrated into a comprehensive topographic map of Mars, providing a detailed depiction of the global radiation landscape.
The construction of this radiation map requires careful consideration of various factors, including atmospheric column density, local and large-scale topography offering potential shielding effects, and the input spectrum is affected by heliospheric modulation. Additionally, accounting for seasonal pressure cycles and daily atmospheric surface pressure due to thermal tides is essential. Our model specifically focused on the influence of zenith angle on atmospheric column depth and simulations tailored to the Gale Crater region, a region explored by the Curiosity rover. 

Applying this methodology allows us to create lookup tables of all secondary particles reaching the Martian surface from various zenith angles and evaluate the atmospheric impact. Employing these matrices alongside the incident spectrum enables the calculation of secondary particle flux from all zenith angles on the Martian surface.

This method provides valuable insights into the fluctuations in radiation flux on Mars, facilitating thorough assessments of potential radiation hazards. Mission planners can leverage these data, obtaining vital information to identify secure landing areas and sheltered regions for astronauts on the Martian surface.

How to cite: Khaksarighiri, S., Wimmer-Schweingruber, R. F., stubbs, T. J., Phipps, P. H., Looper, M. D., Guo, J., Ehresmann, B., Hassler, D. M., Matthiä, D., Zeitlin, C., Löwe, J. L., Berger, T., Löffler, S., and Reitz, G.: The Martian Surface Radiation Environment: Zenith Angle Dependence of Fluxes of Different Secondary Particle Species Produced in the Mars Atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10518, https://doi.org/10.5194/egusphere-egu24-10518, 2024.

EGU24-10573 | ECS | Orals | PS4.2

4000 Sols on Mars - A Long-term Study of Radiation Variations 

Jan Leo Löwe, Robert Wimmer-Schweingruber, Salman Khaksarighiri, Donald Hassler, Jingnan Guo, Bent Ehresmann, Cary Zeitlin, Daniel Matthiä, Thomas Berger, Günther Reitz, and Sven Löffler

The Radiation Assessment Detector (RAD) onboard the Mars Science Laboratory's Curiosity rover is the first-ever instrument continuously monitoring energetic particles on the surface of Mars. Since the rover's landing on August 6, 2012, RAD has accumulated valuable data, providing an unprecedented opportunity to assess the radiation environment across a solar cycle on an another planet.
Understanding the radiation environment on Mars is crucial for a more accurate assessment of the risks posed to manned future space missions. Moreover, it also serves to further investigate planetary conditions, properties of the Sun, and galactic cosmic rays (GCRs). 
 
The radiation field on the surface of Mars primarily consists of charged particles, including primary GCRs propagating to the Martian surface and secondary particles generated through the interaction of primary GCRs with the Martian atmosphere or soil. 
Furthermore, it undergoes temporal changes caused by factors such as atmospheric pressure variations due to thermal tides, seasonal changes, geographical and topographical shielding effects, heliospheric modulation of GCRs, as well as Martian soil and subsurface conditions. Considering all these factors is essential for a comprehensive description of the radiation environment.
 
 Here we utilize the extensive RAD dataset spanning the last 11 years to delve into the intricate variations in particle flux. Our analysis encompasses a diverse array of particle species, providing a comprehensive understanding of how particle flux evolves over the course of one complete solar cycle. This extended time frame allows us to capture and analyze long-term trends, offering valuable insights into the dynamic nature of particle interactions within the Martian environment. By exploring the temporal patterns of particle flux across different species, we aim to contribute to a more nuanced comprehension of the complex radiation dynamics on Mars and its implications for future space missions and potential habitation. 
 
Additionally, we endeavored to understand the impacts of subsurface composition on the Martian surface radiation field, particularly in generating additional upward particles. This investigation is significant as it contributes to the exploration of potential subsurface water content on the surface of Mars.

How to cite: Löwe, J. L., Wimmer-Schweingruber, R., Khaksarighiri, S., Hassler, D., Guo, J., Ehresmann, B., Zeitlin, C., Matthiä, D., Berger, T., Reitz, G., and Löffler, S.: 4000 Sols on Mars - A Long-term Study of Radiation Variations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10573, https://doi.org/10.5194/egusphere-egu24-10573, 2024.

EGU24-10671 | Posters on site | PS4.2

Science goals of the COMPASS instrument consortium on M-MATISSE 

David Andrews, Yoshifumi Futaana, Pierre Henri, Johan De Keyser, David Píša, Ferdinand Platschke, Hanna Rothkaehl, and Štěpán Štverák

Mars–Magnetosphere ATmosphere Ionosphere and Space-weather SciencE (M-MATISSE) is a candidate for the ESA M7 mission opportunity, currently being studied by ESA in Phase A.  It consists of two spacecraft with largely identical scientific payloads that will be placed into orbit around Mars in 2037.  On inclined elliptical orbits they will encounter all relevant regions of the Mars-induced magnetosphere and upper atmosphere for further refining our understanding of the exchange of material, energy and momentum between the solar wind and space environment, and the Martian system. The Combined Magnetic and Plasma Sensor Suite, COMPASS, consists of dual Fluxgate Magnetometers (MAG), dual Langmuir Probes (LP), a Mutual Impedance eXperiment (MIX) (composed of an electronic card Mutual Impedance Board (MIB) that supplies driving electric signals to the Mutual Impedance Probe (MIP)) and a 3D Velocity of Ion (3DVI) instrument (composed of Ion Drift Meter (IDM) and a Retarding Potential Analyzer (RPA) in a combined instrument package), with redundant integrated Wave Analyzer Processing Unit (WAPU) for handling digital data processing and redundant Low Voltage Power Supply (LVPS). Design heritage for COMPASS is derived from the Dust and Fields Package to be flown on Comet Interceptor and from the Radio And Plasma Wave Investigation on the Jupiter Icy Moons Explorer. By sharing physical and electrical resources where possible, COMPASS provides an integrated suite of sensors and data handling systems that will provide highly configurable measurements of plasma properties (density, temperature, velocity and basic composition), as well as the vector magnetic field, a single component of the electric field, and the spacecraft potential. In this presentation, we will review the initial design, expected performance and scientific goals of the COMPASS consortium within the M-MATISSE mission.

How to cite: Andrews, D., Futaana, Y., Henri, P., De Keyser, J., Píša, D., Platschke, F., Rothkaehl, H., and Štverák, Š.: Science goals of the COMPASS instrument consortium on M-MATISSE, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10671, https://doi.org/10.5194/egusphere-egu24-10671, 2024.

EGU24-10733 | ECS | Posters on site | PS4.2

Tianwen-1 and MAVEN Observed Multiple Ion Escape Channels of Mars during an Interplanetary Coronal Mass Ejection 

Fuhao Qiao, Lei Li, Lianghai Xie, Wenya Li, Linggao Kong, Binbin Tang, Taifeng Jin, Yiteng Zhang, Aibing Zhang, Limin Wang, and Jijie Ma

Interplanetary coronal mass ejections (ICMEs) are solar transients that have significant effects on the Martian space environment. The simultaneous spacecraft observations from Tianwen-1 and Mars Atmosphere and Volatile Evolution (MAVEN) are used to study the planetary ion escape for a dramatic ICME. MAVEN passes through the upstream solar wind, +E hemisphere, and -E hemisphere in one orbital period at 20:00 UT -24:00 UT on 2022 April 24. During this period, the interplanetary magnetic field (IMF) remained stable and dominated by the +Y component. In addition to the well-known “plume” escape channels located in the +E hemisphere, MAVEN also observed one ion escape channel in each hemisphere. The additional escape channel located in the +E hemisphere was easily identified as ionized atoms originating from the exosphere, which became significant during CME and was first reported. These ions are observed in both the solar wind and the magnetosheath, and the observed flux of these ions is strongest when MAVEN is very close to the upstream of the bow shock. In this event, ion density of this channel is up to 0.03 cm-3, which is 10 % ~ 30 % of the observed plume. The escape channel structure in the -E hemisphere is complex, and MAVEN has insufficient observation of this channel due to its orbital inclination. Tianwen-1 provided a powerful supplement based on the 1.5 hr observation of this structure, revealing many characteristics of this escape channel. The channel in the -E hemisphere also shows a narrow band in the energy spectrum, similar to the plume. Moreover, its density is between the ion densities of the two +E hemispherical channels. Interestingly, it is more likely to be observed near the magnetic pileup boundary rather than the entire -E hemisphere magnetosheath. These new channels reveal more details of Martian ion escape. The solar wind conditions similar to the early solar system during the ICMEs also help to study the early evolution of Mars.

How to cite: Qiao, F., Li, L., Xie, L., Li, W., Kong, L., Tang, B., Jin, T., Zhang, Y., Zhang, A., Wang, L., and Ma, J.: Tianwen-1 and MAVEN Observed Multiple Ion Escape Channels of Mars during an Interplanetary Coronal Mass Ejection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10733, https://doi.org/10.5194/egusphere-egu24-10733, 2024.

EGU24-10951 | ECS | Orals | PS4.2

The response of Martian magnetotail to interplanetary coronal mass ejection events: joint observations of Tianwen-1 and MAVEN 

Limin Wang, Lei Li, Wenya Li, Lianghai Xie, Yiteng Zhang, Binbin Tang, Linggao Kong, Aibing Zhang, Fuhao Qiao, and Jijie Ma

The Martian magnetotail serves as an important channel for the escape of planetary ions, with abundant dynamic processes. After Tianwen-1 successfully entered the scientific orbit around Mars, the sun is becoming increasingly active. With the orbital apoapsis ~10,760 km, Tianwen-1 completed its first magnetotail phase from March to July 2022, providing a good opportunity to investigate the response of the Martian far magnetotail to interplanetary coronal mass ejections (ICMEs). We made a preliminary analysis of the dynamic tail under an ICME impact on 16 May 2022, with Tianwen-1 monitoring magnetotail and Mars Atmosphere and Volatile EvolutioN (MAVEN) providing upstream measurements. Based on MAVEN observations, the arrival of the ICME was determined to be around 05:10 UT on 16 May 2022. Subsequently, a significant increase in the energy levels of H+ and O+ ions was seen when Tianwen-1 entered the magnetotail about one and a half hours later. Tianwen-1 continuously detected a subset of O+ ions with energies exceeding 1 keV. Accordingly, the escape rate of O+ became ~6.2 times greater during this ICME, and the highest O+ enhancement happened between 1 keV and 3 keV. The disturbance lasted 39 hours before returning to a quiet level. Furthermore, we conducted a statistical analysis on the escape rate of O+ in the far magnetotail (attitude higher than 2 Mars radius) during 11 ICME events from March to July 2022. The ion loss rates substantially increased during ICME events, especially for O+ with energy above several keV. This observation suggests the presence of effective acceleration processes in the Martian tail under ICME conditions.

How to cite: Wang, L., Li, L., Li, W., Xie, L., Zhang, Y., Tang, B., Kong, L., Zhang, A., Qiao, F., and Ma, J.: The response of Martian magnetotail to interplanetary coronal mass ejection events: joint observations of Tianwen-1 and MAVEN, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10951, https://doi.org/10.5194/egusphere-egu24-10951, 2024.

EGU24-12682 | Posters on site | PS4.2

Analysis of Two Selected Solar Events in 2011 and 2015 With Mars Express Radio Occultation Data 

Ananya Krishnan, Ozgur Karatekin, Sebastein Verkercke, Gregoire Henry, Beatriz Sánchez-Cano, and Olivier Witasse

Martian ionosphere has a stratified structure with two main layers in its electron density profile (Ne). The primary layer (M2 layer) is formed by solar EUV radiation (~20-90 nm) and has a peak electron density at around 120-140 km altitude with a peak density of ~1011 m-3. The second layer (M1 layer) occurs at a lower altitude with a peak electron density of ~109 m-3 and is formed by solar X-ray and electron impact ionization. The electron densities and the altitudes at which these peaks occur vary with space weather activities. Radio Occultation (RO) experiments provide vertical electron density profiles that span the entire ionosphere. Therefore, RO experiments are ideal for understanding the variabilities of Martian ionospheric parameters (peak density, peak altitude, and Total Electron Content (TEC)).

Here, we study the effect of solar flares and interplanetary coronal mass ejections (ICMEs) on the Martian ionosphere for two selected solar events in 2011 and 2015, using the publicly available Mars EXpress (MEX) radio occultation (RO) data (MaRS). The 2011 event was associated with a single flare and ICME1 while the 2015 event includes a series of ICMEs and flares2. The MaRS residual Doppler data for the selected periods were processed to obtain the electron density profiles using RO data processing pipeline developed at the Royal Observatory of Belgium3. For both events, the temporal variations of total electron content (TEC) and electron density profiles are retrieved to analyze and quantify the ionospheric response due to solar flares and CMEs.

The analysis showed that the effects of solar events were observable in Mars upper atmosphere for up to several weeks, with the influence gradually decaying following the peak intensity at the arrival of CME. The overall electron density structure showed no evident changes in both events, but a gradual decrease in M2 peak altitude was observed for the 2011 event. An abrupt change in scale height was also observed for some of the profiles in 2011 and 2015, following a high-impact flare or CME. The overall trend of the measured TEC showed a good agreement with the predictions, however, no clear signs of variation due to solar events were observed. All the RO measurements available for this study were 1-4 days earlier or later than the peak events. Thus, this study also points to necessity of having more frequent RO measurements and multi-instrument monitoring of the ionosphere.

Figure 1: The electron density profiles shifted 0.5 units along the x-axis, showing the gradual decrease in M2 peak altitude following the 2011 solar event.

Figure 2:  The SZA, M2 peak density, and M2 peak altitude obtained from MaRS data (black) with 2015 solar events (vertical-coloured lines). The M2 peak density and M2 peak altitude are compared with the NeMars model predictions (green). The NeMars gives these parameters without considering the solar event.

References:

1. Morgan, D. D., et al.,2014, JGR: Space Physics, 119(7), 5891–5908. 

2. Jakosky, B. M., et al., 2015, Science, 350(6261). 

3. Krishnan, A., et al.,2023, Radio Science, 58, e2023RS007784.

 

How to cite: Krishnan, A., Karatekin, O., Verkercke, S., Henry, G., Sánchez-Cano, B., and Witasse, O.: Analysis of Two Selected Solar Events in 2011 and 2015 With Mars Express Radio Occultation Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12682, https://doi.org/10.5194/egusphere-egu24-12682, 2024.

EGU24-13783 | Orals | PS4.2

Inversion of Upstream Solar Wind Parameters from Tianwen-1 H-ENA Observations at Mars 

Yiteng Zhang, Lei Li, Lianghai Xie, Linggao Kong, Wenya Li, Jijie Ma, Binbin Tang, Fuhao Qiao, Limin Wang, Taifeng Jin, and Aibing Zhang

An algorithm has been developed to invert the solar wind parameters from the hydrogen energetic neutral atom (H-ENA) measured in near-Mars space. Supposing the H-ENA is produced by change exchange collision between protons that originated in the solar wind and neutrals in the exosphere, an H-ENA model is established based on the magnetohydrodynamic (MHD) simulation of the solar wind interaction with Mars, to study the H-ENA characteristics. It is revealed that the solar wind H-ENAs are high-speed, low-temperature beams, just like the solar wind, while the magnetosheath H-ENAs are slower and hotter, with broader energy distribution. Assuming Maxwellian velocity distribution, the solar wind H-ENA flux is best fitted by a Gaussian function, from which the solar wind velocity, density, and temperature can be retrieved. Further investigation, based on the ENA flux simulated by the H-ENA model, reveals that the accuracy of inversed solar wind parameters is related to the angular and energy resolutions of the ENA detector. Finally, the algorithm is verified using the H-ENA observations from the Tianwen-1 mission. The upstream solar wind velocity when inversed is close to that of the in situ plasma measurement. Our result suggests the solar wind parameters inversed from H-ENA observation could be an important supplement to the dataset supporting studies on the Martian space environment, where long-term continuous monitoring of the upstream SW condition is lacking.

How to cite: Zhang, Y., Li, L., Xie, L., Kong, L., Li, W., Ma, J., Tang, B., Qiao, F., Wang, L., Jin, T., and Zhang, A.: Inversion of Upstream Solar Wind Parameters from Tianwen-1 H-ENA Observations at Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13783, https://doi.org/10.5194/egusphere-egu24-13783, 2024.

EGU24-14568 | Posters on site | PS4.2

Magnetosheath turbulence and intermittency at Venus, Earth and Mars observed during space weather events 

Marius M. Echim, Luciano Rodriguez, Giovanni Lapenta, Daria Shukhobodskaia, Harikrishnan Aravindakshan, Eliza Teodorescu, and Costel Munteanu

We investigate the effects of space weather events on the properties of turbulence and intermittency detected in the magnetosheath of Venus and Mars and compare with properties detected  in the Earth’s magnetosheath when impacted by the same interplanetary event. We select two Interplanetary Coronal Mass Ejection (ICME) events in 2012 which hit Venus and Earth and one ICME in 2018 which hit Earth and Mars. We use magnetic field and plasma data  provided by Venus Express, Cluster, MMS and MAVEN on which we apply a full set of analysis methods including computation of  Power Spectral Density (PSD), Probability Density Functions (PDFs) and the flatness. We compare the spectral index and the intermittent range of scales (where we observe scale dependent/increasing flatness) obtained for the non-magnetized planets with the same turbulence descriptors obtained for the Earth. We also compare planetary magnetosheath turbulence and intermittency  properties observed during space weather events with quiet times results, for each planetary system.

How to cite: Echim, M. M., Rodriguez, L., Lapenta, G., Shukhobodskaia, D., Aravindakshan, H., Teodorescu, E., and Munteanu, C.: Magnetosheath turbulence and intermittency at Venus, Earth and Mars observed during space weather events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14568, https://doi.org/10.5194/egusphere-egu24-14568, 2024.

Venus and Mars, our two neighboring planets, have no global intrinsic magnetic fields, and the induced magnetospheres are formed in their solar wind interactions through mass loading of magnetic flux tubes carried by the solar wind and draping around the highly conducting ionosphere. Although they have similar global magnetic environments in their induced magnetosphere controlled by the interplanetary magnetic field and the solar wind motional electric field, their differences in planetary size, solar wind conditions, crustal magnetic fields, etc. also have measurable impacts. We comparatively study the magnetic field structures in the Venusian and Martian induced magnetospheres near the terminator via observations. The nature of their current systems and the features of magnetic structures such as flux ropes are examined in the near-terminator space and the effects of solar activity, interplanetary magnetic field, and crustal fields are explored. The results reveal the solar wind interaction with unmagnetized planets near the terminator, and a simulation provides a three‐dimensional view.

How to cite: Xiao, S.: Magnetic Field Structures in the Near-terminator Induced Magnetospheres of Venus and Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14776, https://doi.org/10.5194/egusphere-egu24-14776, 2024.

EGU24-16773 | ECS | Posters on site | PS4.2

Modeling Solar Wind Interaction with Mars through a Ten-ion-species Multifluid MHD Approach 

Jianxuan Wang, Haoyu Lu, and Shibang Li

The configurations of the Martian ionosphere and magnetosphere play a crucial role in the process of ion escape, given that the ionosphere serves as an important source of Martian ion escape and the magnetosphere is closely associated with the escape channels. In this study, we introduced a recently developed three-dimensional multifluid magnetohydrodynamic (MHD) model involving ten ionospheric ion species prevalent on Mars, Ar+, CO2+, CO+, C+, N2+, N+, NO+, O+, O2+, and H+. We solved control equations for each species integrated with their self-consistent chemical reactions. The model successfully reproduced the large-scale structure of bow shock (BS), magnetic pile-up boundary (MPB), and induced magnetosphere consistent with observational statistical results. Benefiting from the consideration of more species and relevant chemical reactions, the model calculated ionospheric profiles are in good agreement with existing studies derived from observations. Moreover, the presence of the crustal magnetic field concentrated in the southern hemisphere of Mars tends to elevate the boundary position of MPB by tens to hundreds of kilometers and impact ion escape processes. Therefore, our model, by calculating ion density and velocity for individual species, can reveal diverse effects of the crustal magnetic field on each ion species.

How to cite: Wang, J., Lu, H., and Li, S.: Modeling Solar Wind Interaction with Mars through a Ten-ion-species Multifluid MHD Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16773, https://doi.org/10.5194/egusphere-egu24-16773, 2024.

EGU24-18658 | ECS | Posters virtual | PS4.2

The response of the cometary ionosphere to space weather forcing 

Aniko Timar, Zoltan Nemeth, and Jim Burch

The Rosetta spacecraft, traversing the inner magnetosphere of comet 67P/Churyumov-Gerasimenko, observed medium-energy ions of cometary origin. These ions, moving in the direction of the cometary nucleus, are likely accelerated in the outer regions of the comet's magnetosphere. Emerging from the low-energy ion background, their signal can reach energies between 50 and 1000 eV over a few hours or days in the ion spectrum measured by the RPC IES sensor of Rosetta. Over a similar time scale, they gradually lose their energy before disappearing again from the measurements. During these medium-energy ion events, the low-energy ion background is depleted. To explain the observed temporal characteristics of the ion spectrum, we investigated the effects of the dynamic pressure of the solar wind surrounding the comet on the medium-energy ions. We demonstrated that there is a very good correlation between the solar wind pressure and the quantity of medium-energy ions detected by Rosetta: when the solar wind pressure increases, the measured amount of medium-energy ions also increases. Additionally, we observe a significant correlation between ion energy and dynamic pressure as well, although the ion energy is also influenced by other parameters, such as cometary activity and the distance from the nucleus.

How to cite: Timar, A., Nemeth, Z., and Burch, J.: The response of the cometary ionosphere to space weather forcing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18658, https://doi.org/10.5194/egusphere-egu24-18658, 2024.

EGU24-1512 | ECS | Orals | ST4.4 | Highlight

Significance of space weather impacts on Automatic Dependent Surveillance (ADS) data 

Erik Schmölter and Jens Berdermann

Safe and efficient management of the constantly growing air traffic is an important task. For that reason, the international civil aviation organization (ICAO) approved Automatic Dependent Surveillance (ADS) system is used to share information (e.g. position, altitude and speed) between aircraft and air traffic control units. This improves the situational awareness and visibility of aircraft but also the environmental impact and air space capacity. Both applications of ADS, Broadcast (B) and Contract (C), rely on satellite-based communication and navigation services, which can be significantly disturbed by space weather impacts (e.g. loss of the signal and position errors). Therefore, related impacts are also observed for ADS records especially during extreme space weather events. We will present such impacts for both, ADS-B and ADS-C, with first results from an analysis covering periods with solar flares and geomagnetic storms. We will also discuss the challenge of differentiating space weather impacts from other influences. Finally, we will give an outlook how monitoring these impacts could contribute to space weather services.

How to cite: Schmölter, E. and Berdermann, J.: Significance of space weather impacts on Automatic Dependent Surveillance (ADS) data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1512, https://doi.org/10.5194/egusphere-egu24-1512, 2024.

EGU24-3363 | ECS | Posters on site | ST4.4

An operational geomagnetic baseline derivation for ground magnetometer data located in mid-latitudinal regions 

Veronika Haberle, Aurélie Marchaudon, Aude Chambodut, and Pierre-Louis Blelly

As a direct response to the increasing dependency on technological systems, the need for operational now- and forecasting of space weather events has been rising within the past decades.

In order to monitor these events and their impacts, ground magnetic field data has proven to be a long-lasting and powerful source of information. Especially for the determination of the intensity and strength of solar forcing events, the derivation of geomagnetic baselines that extract the solar forcing portion from the rest of the superposing sources within geomagnetic field signals are of importance.

In this work, we present a derivation method for determining the geomagnetic baseline for magnetic field data recorded at mid-latitudes. The contributing sources include the secular variation and the day-to-day variability, enabling the extraction of solar forcing contributions accurately. The derivation method is based on standard algorithms and does not need a-priori information other than the geomagnetic field measurements themselves. This enables the production of the baseline in near-real time and is thus suitable for operational purposes.

The deployment of the introduced baseline allows for the operational identification of solar forcing intensities and may also be used for derivation of magnetic indices that use magnetic field data from mid-latitudinal observatories.

How to cite: Haberle, V., Marchaudon, A., Chambodut, A., and Blelly, P.-L.: An operational geomagnetic baseline derivation for ground magnetometer data located in mid-latitudinal regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3363, https://doi.org/10.5194/egusphere-egu24-3363, 2024.

EGU24-4076 | Orals | ST4.4

Collection, Collation, and Comparison of 3D Coronal CME Reconstructions 

Christina Kay and Erika Palmerio

Predicting the impacts of coronal mass ejections (CMEs) is a major focus of current space weather forecasting efforts. Typically, CME properties are reconstructed from stereoscopic coronal images and then used to forward model a CME's interplanetary evolution. Knowing the uncertainty in the coronal reconstructions is then a critical factor in determining the uncertainty of any predictions. A growing number of catalogs of coronal CME reconstructions exist, but no extensive comparison between these catalogs has yet been performed. Here we develop a Living List of Attributes Measured in Any Coronal Reconstruction (LLAMACoRe), an online collection of individual catalogs, which we intend to continually update. In this first version, we use results from 24 different catalogs with 3D reconstructions using STEREO observations between 2007-2014. We have collated the individual catalogs, determining which reconstructions correspond to the same events. LLAMACoRe contains 2954 reconstructions for 1862 CMEs. Of these, 511 CMEs contain multiple reconstructions from different catalogs. Using the best-constrained values for each CME, we find that the combined catalog reproduces the generally known solar cycle trends. We determine the typical difference we would expect between two independent reconstructions of the same event and find values of 4.0 deg in the latitude, 8.0 deg in the longitude, 24.0 deg in the tilt, 9.3 deg in the angular width, 0.1 in the shape parameter kappa, 115 km/s in the velocity, and 2.5e15 g in the mass. These remain the most probable values over the solar cycle, though we find more extreme outliers in the deviation toward solar maximum.

How to cite: Kay, C. and Palmerio, E.: Collection, Collation, and Comparison of 3D Coronal CME Reconstructions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4076, https://doi.org/10.5194/egusphere-egu24-4076, 2024.

EGU24-4674 | Posters on site | ST4.4

Parameter estimation of the geomagnetic activity model by non-linear least squares 

Martina Ćorković, Giuliana Verbanac, and Mario Bandić

Geomagnetic disturbances during coronal mass ejections (CMEs), which are powerful plasma ejections from Sun’s corona, pose significant challenges for space weather forecasting. In this study, we propose an improvement to the O’Brien-McPherron model [1] for forecasting the storm-time disturbance index Dst, a key parameter reflecting geomagnetic storm intensity during CMEs, in terms of solar wind parameters. By optimizing the parameters of the O’Brien-McPherron model with respect to the sunspot number, we enhanced the model’s performance for both very low and high solar activity.

We have analysed 48 CME-induced geomagnetic storms from 1996 to 2020 and grouped them in four different solar activity levels based on the mean number of sunspots during each storm. We derived the new optimal values for three model parameters for each activity level by employing a non-linear least squares approach, specifically utilizing the Levenberg-Marquardt algorithm.

By taking into account the number of sunspots during a geomagnetic storm, we successfully mitigated the model’s tendency to consistently overestimate the intensity of very weak geomagnetic storms in the very low solar activity level. While the average difference between the forecasted maximum storm intensity and the observed intensity for the regular O’Brien-McPherron model is 17 nT, the optimized model demonstrates a notably reduced difference of 2 nT. Simultaneously, we expanded the model’s applicability to include hazardous superstorms (Dst < -150 nT) occurring during high solar activity, effectively preventing the substantial underestimation of their intensity. The O’Brien-McPherron model is not suited for superstorms and exhibits deviations of about 100 nT in forecasting their maximum intensity, whereas the optimized model underestimates it on average by only 25 nT.

Geomagnetic superstorms can induce very strong electrical currents in power grids, navigation and communication systems and satellites. Underestimating their impact can lead to insufficient shielding and permanent damage of these systems. Enhancing our ability to forecast these events with greater precision, as demonstrated by the improved performance of the optimized model, is crucial in minimizing disruptions and safeguarding infrastructure and technology.

[1] O'Brien, T. P., and R. L. McPherron (2000), An empirical phase space analysis of ring current dynamics: Solar wind control of injection and decay, J. Geophys. Res., 105(A4), 7707–7719, doi:10.1029/1998JA000437.

How to cite: Ćorković, M., Verbanac, G., and Bandić, M.: Parameter estimation of the geomagnetic activity model by non-linear least squares, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4674, https://doi.org/10.5194/egusphere-egu24-4674, 2024.

EGU24-4766 | ECS | Posters on site | ST4.4

Ground-level neutron monitoring survey over the United Kingdom 

Dakalo Mashao, Tilly Alton, Cory Binnersley, Steve Bradnam, Stephen Croft, Malcolm Joyce, Lee Packer, Tony Turner, Jim Wild, and Michael Aspinall

Space weather events impose a threat on critical infrastructures such as electrical power grids, global navigation satellite systems, satellite operations, aviation technology and radio communication channels at various frequencies. We present an update on a new ground-level neutron monitor (NM-2023) which will be used to monitor space weather events, namely the detection and alert of ground-level enhancement (GLE) events. The NM-2023 will provide data to entities such as the United Kingdom Meteorological Office, the Neutron Monitor Database (NMDB), and the University of Surrey. We also report on a neutron monitoring survey conducted using a pair of subsystems deployed at several UK field sites. The data collected by these subsystems will be compared across the various sites, to data collected using a partial NM-2023 instrument and with data from established NMDB instruments with similar geomagnetic cutoff rigidities.

How to cite: Mashao, D., Alton, T., Binnersley, C., Bradnam, S., Croft, S., Joyce, M., Packer, L., Turner, T., Wild, J., and Aspinall, M.: Ground-level neutron monitoring survey over the United Kingdom, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4766, https://doi.org/10.5194/egusphere-egu24-4766, 2024.

Ensemble Data assimilation is a state-of-the-art method that can combine the observation information into a numerical model and further improve the performance of numerical weather prediction of the thermosphere and ionosphere.  The thermospheric and ionospheric weather are highly sensitive to the variation of forcings from above, including the solar irradiance and the magnetospheric forcings, and forcings from below, including waves and tides from the lower atmosphere. However, these forcings are hard to quantify. Building up the connection between the uncertainty of the forcings and the variability of a numerical model of the thermosphere and ionosphere that is used in a data assimilation system is a critical issue in thermospheric and ionospheric weather prediction.

This study aims to advance our understanding of how solar irradiance variability and tide and wave variability drive the variability of Earth's thermosphere and ionosphere and improve our capability to represent this driver-response relationship in physics-based models using ensemble data assimilation. This study focuses on the National Center for Atmospheric Research’s (NCAR’s) Whole Atmosphere Community Climate Model – eXtended (WACCM-X). In the WACCM-X, the solar irradiance is determined by an empirical model, such as EUVAC, or by a real data set, and the waves and tides are generated self-consistently from the lower atmosphere in the model.

We first try to quantify the solar irradiance variability in different wavelengths based on real data, including data from the Extreme Ultraviolet Variability Experiment (EVE) on Solar Dynamics Observatory (SDO) and the X-ray Photometer System (XPS)and the Solar Stellar Irradiance Comparison Experiment (SOLSTICE) on Solar Radiation and Climate Experiment (SORCE). Then, we quantify and qualify the response of the thermosphere and ionosphere in the WACCM-X to both the variation of solar irradiance and waves and tides by launching a set of ensemble simulation experiences. This will help prove the predictability of the thermospheric and ionospheric weather. 

How to cite: Hsu, C. T. and Pedatella, N.: Effects of Forcing Uncertainties on the Thermospheric and Ionospheric Ensemble-based data assimilation., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4913, https://doi.org/10.5194/egusphere-egu24-4913, 2024.

EGU24-5109 | ECS | Orals | ST4.4 | Highlight

A novel full MHD forecasting model chain from Sun to Earth: COCONUT+ Icarus 

Tinatin Baratashvili, Michaela Brchnelova, Jin Han Guo, Andrea Lani, and Stefaan Poedts

Space weather events can affect Earth. In order to mitigate damage, space weather modelling tools have been implemented. In this study, the full MHD chain is presented, starting from the Sun, with a 3D MHD data-driven coronal model COCONUT up to 0.1 AU, where the code is coupled to Icarus, an ideal 3D MHD heliospheric modelling tool.

COCONUT (Perri, Leitner et al. 2022, COolfluid COrona Unstructured) is a data-driven coronal model that was recently developed at the Centre for Mathematical Plasma Astrophysics, KU Leuven. It is a global 3-D MHD model based on the COOLFluiD code (Yalim et al. 2011, Lani et al. 2014). The advantage of the COCONUT model lies in its efficient, optimised implementation. It uses a time-implicit backward Euler scheme and unstructured computational grid, which avoids singularities near the poles and enables using high CFL numbers to rapidly converge to steady state for realistic simulations on modern HPC systems. In order to obtain realistic solar wind conditions at 0.1AU, the source terms have been implemented in the MHD equations, namely, the approximated coronal heating function, radiative losses and the thermal conduction. The output of the COCONUT coronal model is used as input boundary conditions for plasma variables in the heliospheric model Icarus.

Icarus (Verbeke et al. 2022, Baratashvili et al. 2022) is a new heliospheric wind and CME evolution model that is implemented within the framework of MPI-AMRVAC (Xia et al., 2018) and introduces new capabilities for better and faster space weather forecasts. Advanced numerical techniques, such as solution adaptive mesh refinement (AMR) and radial grid stretching, are implemented. These techniques result in optimised computer memory usage and a significant execution speed-up, which is crucial for forecasting purposes.

The modelled 3D data in the solar corona and heliosphere are presented for assessing the model capabilities. The density profiles near the Sun are compared to tomography data. The time-series profiles of different variables at Earth are compared to observational data. As a result, the COCONUT+Icarus model chain represents the full MHD model covering the domain from Sun to Earth, which allows more in depth studies and understanding of different physics phenomena, e.g. shock formation, erosion, and deformation, compared to empirical or semi-empirical models. 

How to cite: Baratashvili, T., Brchnelova, M., Guo, J. H., Lani, A., and Poedts, S.: A novel full MHD forecasting model chain from Sun to Earth: COCONUT+ Icarus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5109, https://doi.org/10.5194/egusphere-egu24-5109, 2024.

EGU24-5357 | Posters on site | ST4.4

Utilising Heliospheric Images for Space Weather Prediction: A Data Assimilation Strategy 

Tanja Amerstorfer, Jackie A. Davies, David Barnes, Maike Bauer, Justin LeLouëdec, Eva Weiler, and Christian Möstl

The STEREO mission has paved the way for the forthcoming Vigil mission, set to launch around 2030. Based on the extensive data archives from STEREO's wide-angle cameras, the heliospheric imagers (HI), we aim to assess the suitability of these data for real-time space weather prediction.
This study focuses on modeling the evolution of coronal mass ejections (CMEs) as they progress towards Earth, employing STEREO-A and STEREO-B observations from Vigil's future vantage point, the L5 point of the Sun-Earth system, with the drag-based ensemble model ELEvoHI.
Our investigation aims to determine to what extent incorporating additional HI data (as it would be received in real-time) improves the forecasting accuracy and its impact on the prediction lead time.

How to cite: Amerstorfer, T., Davies, J. A., Barnes, D., Bauer, M., LeLouëdec, J., Weiler, E., and Möstl, C.: Utilising Heliospheric Images for Space Weather Prediction: A Data Assimilation Strategy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5357, https://doi.org/10.5194/egusphere-egu24-5357, 2024.

EGU24-5927 | Posters on site | ST4.4 | Highlight

Extending back in time the Kp-like, open-ended, high-cadence geomagnetic Hp60 and Hp30 indices to cover the period starting from 1985 

Guram Kervalishvili, Jürgen Matzka, Yosuke Yamazaki, Jan Rauberg, and Marcos Vinicius da Silva

Geomagnetic indices are commonly used for various purposes, including the characterization of geomagnetic disturbance levels, parametrization of physical and empirical models of the near-Earth space environment, and data (re)analysis. The Kp (and ap) index, which is derived and disseminated by the GFZ German Research Centre for Geosciences, is one of the most extensively used such indices. The Kp index has been available since 1932 and therefore is particularly useful for studying long-term space climate trends. However, the Kp temporal resolution is limited to a three-hourly interval, which means that it cannot correctly capture rapid changes in geomagnetic activity that occur on shorter timescales. Secondly, the Kp index has an upper limit of 9, which means that all events of extremely disturbed conditions are described with one single number, which makes it difficult to differentiate between different levels of extreme geomagnetic activity.

We developed a new family of geomagnetic indices, called Hpo (“H” stands for half-hourly or hourly, “p” for planetary, and “o” for open-ended). This open-ended, high-cadence index family is similar to the Kp index in its representation of planetary geomagnetic activity, but with higher time resolution and without an upper limit. The Hpo index family consists of the half-hourly Hp30 and the hourly Hp60 indices, as well as their linear versions, the ap30 and ap60 indices. The Hpo index family is based on the same 13 geomagnetic observatory data as the Kp index. Previously, the Hpo index values were only available back to 1995. However, we have recently derived Hpo indices for the period from 1985 to 1994. This period includes several strong geomagnetic storms in 1989-1992 that have been analysed using the newly derived Hpo indices. The Hpo index family provides a more comprehensive view of the geomagnetic activity, allowing for better analysis and understanding of space weather.

How to cite: Kervalishvili, G., Matzka, J., Yamazaki, Y., Rauberg, J., and da Silva, M. V.: Extending back in time the Kp-like, open-ended, high-cadence geomagnetic Hp60 and Hp30 indices to cover the period starting from 1985, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5927, https://doi.org/10.5194/egusphere-egu24-5927, 2024.

EGU24-6683 | Orals | ST4.4 | Highlight

Operation and developments of the Whole-Atmosphere-Model at NOAA Space Weather Prediction Center 

Astrid Maute, Tzu-Wei Fang, Timothy Fuller-Rowell, Adam Kubaryk, Zhuxiao Li, George Millward, and Brian Curtis

The coupled Whole Atmosphere Model - Ionosphere Plasmasphere Model (WAM-IPE) has been transitioned into operations at the NOAA Space Weather Prediction Center (SWPC) in 2021. WAM is an extension of the NOAA National Weather Service (NWS) operational model and calculates Earth’s global three-dimensional, time-dependent, neutral atmosphere from the surface up to the thermosphere at 10^-7 hPa (400-600 km). WAM is coupled to the global ionosphere-plasmasphere electrodynamics (IPE) model which extends to several Earth radii. The model is providing a forecast of the neutral and plasma environment that impacts the GNSS positioning, global communications, and collision avoidance for space traffic management.

In this presentation, we describe the different Concept of Operations (CONOPS) which provide nowcast and forecast with WAM-IPE and the validation efforts. We discuss several developments based on the operational version of WAM, which includes the data-assimilation system for WAM and the high-resolution WAM-IPE. A recent testbed exercise targeted satellite operator and solicited feedback from operators and service providers which informs future developments.  We will conclude with the future plans to update WAM to the Finite-Volume Cubed-Sphere Dynamical Core (FV3) version.

How to cite: Maute, A., Fang, T.-W., Fuller-Rowell, T., Kubaryk, A., Li, Z., Millward, G., and Curtis, B.: Operation and developments of the Whole-Atmosphere-Model at NOAA Space Weather Prediction Center, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6683, https://doi.org/10.5194/egusphere-egu24-6683, 2024.

EGU24-7574 | ECS | Posters on site | ST4.4 | Highlight

An Open Platform for Validating Ambient Solar Wind Models 

Barbara Perri, Martin Reiss, Karin Muglach, Evangelia Samara, Richard Mullinix, and Chiu Wiegand and the ISWAT Ambient Solar Wind Validation Team

To drive innovation in space weather research and prediction, we need to seek out promising strategies for unifying the validation of our modeling assets. Here we present the activities of the Ambient Solar Wind Validation Team embedded in the COSPAR ISWAT initiative. Our team's mission is to create an open online platform for validating ambient solar wind models at NASA's Community Coordinated Modeling Center. This open platform will allow the community to easily assess the accuracy of state-of-the-art solar wind model solutions in terms of unified metrics, and will thereby provide an unbiased assessment of progress over time. In this presentation, we will introduce the online platform, highlight our progress in developing unified metrics for both historical and near real-time validation, and discuss the current status and future perspectives of this community effort.

How to cite: Perri, B., Reiss, M., Muglach, K., Samara, E., Mullinix, R., and Wiegand, C. and the ISWAT Ambient Solar Wind Validation Team: An Open Platform for Validating Ambient Solar Wind Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7574, https://doi.org/10.5194/egusphere-egu24-7574, 2024.

EGU24-7575 | Orals | ST4.4 | Highlight

Thermosphere model assessment and implementation at NASA/CCMC 

Sean Bruinsma, Sophie Laurens, Jack Wang, Jia Yue, and Maria Kuznetsova

Appropriate metrics to track the progress over time of thermosphere models, both first principle and semi-empirical, were developed. Secondly, the high quality and high-spatial resolution neutral density data sets of TU Delft covering long intervals of time (i.e. the complete CHAMP, GRACE, GRACE-FO and GOCE mission datasets) were selected. The neutral density observations can then be used to verify model accuracy with respect to latitude-longitude-local time variations, and solar and geomagnetic activity levels and seasonal variations, respectively. The density data and metrics together allow benchmarking of the models, and improvement from one release to the next can be quantified. An assessment tool was implemented at CCMC specifically for storm-time assessment, while global assessment capacity is currently also under development.

In this study, we present the results of comparisons with storms from 2001-2022 for the DTM2020, NRLMSISE-00 and JB2008 models. Secondly, the CCMC CAMEL model assessment tool will be shown and the model score cards that it can generate. These score cards allow easy and objective comparison of the performance of thermosphere models.

How to cite: Bruinsma, S., Laurens, S., Wang, J., Yue, J., and Kuznetsova, M.: Thermosphere model assessment and implementation at NASA/CCMC, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7575, https://doi.org/10.5194/egusphere-egu24-7575, 2024.

EGU24-7852 | Orals | ST4.4 | Highlight

Lessons learned from modelling flux ropes with EUHFORIA 

Eleanna Asvestari

Due to their socioeconomic impact, the forecasting of coronal mass ejections (CMEs) is of paramount importance. This has led to decades of model development based on the knowledge we have gained from observations and our understanding of the physical processes that take place and could explain these observations. Currently we have empirical and magnetohydrodynamic (MHD) models that show promising results in CME forecasting. However, these are observationally driven and strongly dependent on the quality and quantity of observations we have at our disposal. The vast majority of our CME observations are made on the ecliptic plane. And in situ observations are collected by a few spacecraft scattered in the same plane. In the case of MHD models, we are also limited by numerical implementation issues and our understanding of the CME plasma and magnetic structure, as well as the physical processes CMEs undergo during their journey in the heliosphere.

EUHFORIA (EUropean Heliospheric FORecasting Information Asset), is a state-of-the-art 3-dimensional MHD model that can simulate CMEs in the inner heliosphere, either as hydrodynamic pulses (cone model) or magnetised flux ropes (spheromak, FRiED-3D, torus). Throughout this presentation we will explore the observable parameters the CME implementations in EUHHFORIA depend on and how they are impacted by observational limitations. We will also discuss the performance of the spheromak CME and how we can track it with a novel tool. Last but not least, we will discuss the physical processes manifested in spheromak CME simulations and how they can shed light on the evolution of 3D flux ropes in the interplanetary space depending on the ambient medium (solar wind and interplanetary magnetic field) they are embedded in.

How to cite: Asvestari, E.: Lessons learned from modelling flux ropes with EUHFORIA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7852, https://doi.org/10.5194/egusphere-egu24-7852, 2024.

EGU24-8210 | ECS | Orals | ST4.4

Encoding the drag-based model in the artificial intelligence training process to predict CMEs’ travel times 

Sabrina Guastavino, Michele Piana, Anna Maria Massone, Francesco Marchetti, Federico Benvenuto, Alessandro Bemporad, Roberto Susino, and Daniele Telloni

The study of space weather impacts of coronal mass ejections (CMEs) requires the formulation, implementation and validation of predictive approaches to address issues such as the arrival of CMEs to Earth and, if so, its arrival time and speed. The problem of predicting the CMEs’ travel times has been addressed by means of empirical models, physics-based models, and artificial intelligence techniques. In this talk, we propose a physics-driven artificial intelligence (AI) method, in which we encode physical information into the process of neural network training. Specifically we include the drag-based model in the definition of the loss functions to minimize during the training process of a cascade of two neural networks fed with both remote sensing and in situ data. We show that including physical information in the AI architecture improves its predictive capabilities and the proposed physics-driven AI method leads to more accurate and robust results for the CMEs’ travel time prediction with respect to the purely-data driven AI approach.

How to cite: Guastavino, S., Piana, M., Massone, A. M., Marchetti, F., Benvenuto, F., Bemporad, A., Susino, R., and Telloni, D.: Encoding the drag-based model in the artificial intelligence training process to predict CMEs’ travel times, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8210, https://doi.org/10.5194/egusphere-egu24-8210, 2024.

EGU24-8224 | ECS | Posters on site | ST4.4

Ensemble analogue methodology for the forecast of turbulent properties in the solar wind  

Pauline Simon and Christopher Chen

The solar wind is a plasma which is known to be highly turbulent. The subsequent non-linear cascades of, for instance, energy influence the behaviour at a wide range of scales of the observable quantities, such as the magnetic field and velocity. The small-scale behaviour can be seen as an a priori predictable “noise” that could impact space weather forecasts. Such an impact is usually neglected because the resolution of solar wind forecast models is not sufficient, due to computational limitations. As a first step in the turbulent-oriented improvement of space weather forecasts, we have tackled the question of how predictable different aspects of the small-scale turbulence in the solar wind are. We have used the ensemble analogue methodology, which assumes that future events are predictable based on what has happened in the past, and test this on the solar wind turbulence properties. We will discuss our results in terms of their implications for solar wind and space weather forecasting.

How to cite: Simon, P. and Chen, C.: Ensemble analogue methodology for the forecast of turbulent properties in the solar wind , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8224, https://doi.org/10.5194/egusphere-egu24-8224, 2024.

Earlier studies have shown that geomagnetic activity, used as a proxy for energetic particle precipitation (EPP), can influence the wintertime weather conditions, e.g. temperature and wind speed, on the surface of the Earth. This effect is transmitted via the polar vortex, the westerly wind system circulating the polar area during winter, which can intensify due to increased EPP activity. Stronger vortex tends to cause mild, wet and more windy winter weather in Northern Europe while weaker vortex leads to cold, dry and less windy winter weather. The EPP effect on the vortex is greatly dependent on the phase of the equatorial stratospheric zonal winds, called quasi-biennial oscillation (QBO), and is stronger during easterly QBO winds.

Previously it has been shown that the EPP effect on the polar vortex influences the wintertime electricity consumption in Finland that is greatly dependent on the outdoor temperature.  Since the strength of the polar vortex also affects the wind speed on ground, we now study how energetic particle precipitation would influence the electricity production by wind power.

In general, the electricity production by wind turbines is proportional to the wind speed. Here we find that during easterly QBO winds the geomagnetic aa index (proxy for EPP) correlates significantly with the wintertime wind speed in Finland and Sweden and also with the wintertime electricity production by wind power. This correlation can explain about 30-40% of the inter-annual variations of wintertime wind power production in these countries during QBO-E winters.

How to cite: Juntunen, V. and Asikainen, T.: Energetic particle precipitation (EPP) influencing the electricity production by wind power in Northern Europe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8743, https://doi.org/10.5194/egusphere-egu24-8743, 2024.

EGU24-9269 | Posters on site | ST4.4

Implementing and verifying the algorithm used for generating Swarm L2 Fast-track data products 

Jan Rauberg, Ingo Michaelis, Martin Rother, Monika Korte, and Guram Kervalishvili

The Swarm mission of the European Space Agency (ESA) consists of three identical satellites named Alpha (A), Bravo (B), and Charlie (C), launched in a near-polar orbit on 22 November 2013. It is the first constellation mission for Earth Observation at Low Earth Orbit (LEO), which achieved the initial constellation on 17 April 2014, with Swarm A and C flying side-by-side at an altitude of about 470 km and Swarm B at an altitude of around 520 km. All of the satellites in the Swarm mission are equipped with six high-precision instruments which are identical and provide high-level data products for the past decade. These instruments include an absolute scalar and vector field magnetometer, a star tracker, an electric field instrument (Langmuir probe and thermal ion imager), a GPS receiver, and an accelerometer.

The Swarm L1b fast-track (FAST) operational chain data are distributed more rapidly and frequently in comparison with the standard product provision (OPER), which is typically available after three days. The concept of FAST data products refers to the reduced time interval between the occurrence of an event and its detection or measurement. This significantly increases the applicability of Swarm data in the field of space weather monitoring and forecasting. We performed a quality check of FAST data against OPER data for L1b products that are required as an input for the GFZ L2 data product processing chain. Here, several GFZ Swarm L2 FAST data products are shown that have been tested and implemented for operational maintenance. The quality check and operational readiness have been analysed for geomagnetically quiet and disturbed periods. Overall, these products are suitable for the FAST operational chain.

How to cite: Rauberg, J., Michaelis, I., Rother, M., Korte, M., and Kervalishvili, G.: Implementing and verifying the algorithm used for generating Swarm L2 Fast-track data products, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9269, https://doi.org/10.5194/egusphere-egu24-9269, 2024.

EGU24-9309 | ECS | Orals | ST4.4

High time resolution mapping of polar ionospheric flows with the SuperDARN Borealis systems 

Daniel Billett, Remington Rohel, Kathryn McWilliams, Carley Martin, Karl Laundal, and Jone Reistad

Over the last few years, the five SuperDARN HF ionospheric radars operated by the University of Saskatchewan have been upgraded to digital systems that utilise the flexibility and reliability of software defined radios (SDRs). SDRs allow for a vastly greater control of radar transmit and receive operations, bringing with them new capabilities for scientific experiments that were previously not feasible on analogue hardware. This next generation of SuperDARN radar is named Borealis. 

 

One new radar operating mode implemented at the Borealis radars has been full field-of-view imaging. On traditional SuperDARN radars, one full scan of an entire field-of-view (an area encompassing thousands of kilometres at F-region ionospheric altitudes) takes approximately 1 minute as each of the 16 beam directions is sequentially integrated over. With Borealis, every beam direction can be probed (or “imaged”) simultaneously, providing a 16-fold improvement in scan temporal resolution to 3.5 seconds.

 

We present a new ionospheric data product derived from Borealis imaging mode data: high time resolution mapping of polar E x B drifts. In contrast to traditional SuperDARN ionospheric convection patterns which are nominally derived every two minutes on a coarse global grid, Borealis convection patterns are derived locally over the Canadian polar cap every few seconds. This not only provides the opportunity to study mesoscale ionospheric phenomena like polar cap patches, flow channels, and substorms, but also allows for doing so at a temporal resolution not previously possible without compromising spatial coverage.

How to cite: Billett, D., Rohel, R., McWilliams, K., Martin, C., Laundal, K., and Reistad, J.: High time resolution mapping of polar ionospheric flows with the SuperDARN Borealis systems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9309, https://doi.org/10.5194/egusphere-egu24-9309, 2024.

EGU24-9684 | ECS | Orals | ST4.4

Comparison of geomagnetically induced currents in the US and UK power grid using network analysis 

Lauren Orr, Sandra Chapman, and Ryan McGranaghan

During geomagnetic storms the electrical power grid is vulnerable to geomagnetically induced currents (GICs) caused by sharp changes in magnetic and geoelectric fields. In the UK the measurement of GIC in the power grid is extremely limited with most GIC estimates coming from a model of the high voltage grid. The US has collected geomagnetic disturbance (GMD) data for 18 geomagnetic storms. Network theory is routinely used to estimate the resilience of the physical power grid, and its robustness to the removal of nodes, when faced with threats ranging from natural hazards to cyber-attacks but is currently not applied to GIC. By applying network theory to both the modelled UK dataset and measured US dataset, we can utilize known parameters to test for vulnerabilities to space weather in the power grid across varying spatial and temporal scales. The network is formed using methods of association between the GIC data at each transformer. The monitors are the nodes of the network and the links are defined as when the wavelet cross-correlation of the GIC is sufficiently high (1). The wavelet transform is used to localise the GIC response to the storm across time scales. Whilst previous network science studies have focused on the physical topology of the power grid, our method focuses on the dynamical response of the grid to GIC. Despite the difference in latitude and local time we see many similarities between the modelled UK and measured US GIC data, particularly during the sudden commencement. Initial results show the same nodes repeatedly appearing as the most highly connected to the network across multiple events. These nodes could be key to providing resilience and/or prediction of forthcoming disturbance of the power grid in the event of a large geomagnetic storm.

(1) Orr, L., Chapman, S. C., Beggan, C. D. (2021). Space Weather, 19, e2021SW002772.

How to cite: Orr, L., Chapman, S., and McGranaghan, R.: Comparison of geomagnetically induced currents in the US and UK power grid using network analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9684, https://doi.org/10.5194/egusphere-egu24-9684, 2024.

EGU24-9938 | ECS | Posters on site | ST4.4

Sudden Storm Commencement detection with SVM classifiers using ground magnetic data 

Frédéric Tournier, Vincent Lesur, and Pierdavide Coïsson

When a cloud of plasma from a corona mass ejection hits the Earth's magnetosphere, a rapid perturbation of the magnetopause current systems occurs. It generates a signal that is detected worldwide by ground magnetic observatories in the form of a Sudden Storm Commencement (SSC). This signal has an amplitude of approximatively 20 nT but is similar to signals generated by other phenomena. Existing lists of SSCs had been set by human inspection of magnetic time series. We have implemented and tested a method to automatically detect SSC events using Support Vector Machines (SVM) classifiers within one-second data collected in the network of IPGP magnetic observatories.

How to cite: Tournier, F., Lesur, V., and Coïsson, P.: Sudden Storm Commencement detection with SVM classifiers using ground magnetic data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9938, https://doi.org/10.5194/egusphere-egu24-9938, 2024.

EGU24-10110 | Orals | ST4.4 | Highlight

Prediction of Adverse effects of Geomagnetic storms and Energetic Radiation (PAGER) – project conclusion 

Yuri Shprits, Stefano Bianco, Dedong Wang, Bernhard Haas, Muhammad Asim Khawaja, Karina Wilgan, Tony Arber, Keith Bennett, Ondrej Santolik, Ivana Kolmasova, Ulrich Taubenschuss, Mike Liemohn, Bart van der Holst, Julien Forest, Arnaud Trouche, and Benoit Tezenas du Montcel

The European Union's Horizon 2020 Prediction of Adverse effects of Geomagnetic storms and Energetic Radiation (PAGER) project was successfully concluded in 2023. This project provides real-time space weather forecast initiated from the solar observations as well as predictions of radiation in space and its effects on satellite infrastructure. Real-time predictions of particle radiation and cold plasma density allow for evaluation of surface charging and deep dielectric charging. The project provides a 1-2-day probabilistic and data assimilative forecast of ring current and radiation belt environments, which allows satellite operators to respond to predictions that present a significant threat. As a backbone of the project, we use the state-of-the-art codes that currently exist and adapt existing codes to perform ensemble simulations and uncertainty quantifications. Within PAGER, a number of innovative tools was obtained, including data assimilation and uncertainty quantification, new models of near-Earth electromagnetic wave environment, ensemble predictions of solar wind parameters at L1, and data-driven forecast of the geomangetic Kp index and plasma density. In this presentation, we show the overview of the outcomes and the products obtained within the project. The developed codes may be used in the future for realistic modelling of extreme space weather events.

How to cite: Shprits, Y., Bianco, S., Wang, D., Haas, B., Khawaja, M. A., Wilgan, K., Arber, T., Bennett, K., Santolik, O., Kolmasova, I., Taubenschuss, U., Liemohn, M., van der Holst, B., Forest, J., Trouche, A., and Tezenas du Montcel, B.: Prediction of Adverse effects of Geomagnetic storms and Energetic Radiation (PAGER) – project conclusion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10110, https://doi.org/10.5194/egusphere-egu24-10110, 2024.

EGU24-10294 | Posters on site | ST4.4

Validation of Model Results in Response to the COSPAR ISWAT Challenge 

Dedong Wang, Yuri Shprits, Angelica Maria Castillo Tibocha, and Alexander Drozdov

The COSPAR International Space Weather Action Team (ISWAT) is a global hub for collaborations addressing challenges across the field of space weather. One of the objectives of the G3-04 team “Internal Charging Effects and the Relevant Space Environment” is model performance assessment and improvement. One of the expected outputs is a more systematic assessment of model performance under different conditions. The G3-04 team proposed performing benchmarking challenge runs. In this study, in response to the first benchmarking challenge (long-term simulation), we perform simulations for the year 2017 to validate the Versatile Electron Radiation Belt (VERB) code. The challenge requires not using any of the measurements from the NASA' s Van Allen Probes for setting up parameters of the code, such as boundary and initial conditions. In our simulations, we use data from the Geostationary Operational Environmental Satellites (GOES) to set up the outer boundary condition, which is the only data input for simulations. We validate our simulation results against measurements from Van Allen Probes. In particular, we ‘fly’ a virtual satellite through our simulation results and compare the simulated differential electron fluxes at 0.9 MeV and 57.27 degrees local pitch-angle with the fluxes measured by the Van Allen Probes. In general, our simulation results show good agreement with observations. We calculated several different matrices to validate our simulation results against satellite observations. Using the similar approach, we extend our simulations to several years long period and validate our simulation results against satellite observations in both long-term and specific geomagnetic storms. Several different validation matrices are calculated for both long-term and specific events.

How to cite: Wang, D., Shprits, Y., Castillo Tibocha, A. M., and Drozdov, A.: Validation of Model Results in Response to the COSPAR ISWAT Challenge, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10294, https://doi.org/10.5194/egusphere-egu24-10294, 2024.

EGU24-10799 | ECS | Posters on site | ST4.4

Contribution of DORIS System to Global Ionospheric Scintillation Mapping 

Marie Cherrier and Philippe Yaya

Ionospheric scintillations due to ionosphere irregularities may severely degrade GNSS data in equatorial and high latitudes regions, and consequently the applications that rely on such data. It is thus of high importance for many users in a large variety of applications to have access to global maps of scintillation intensity, for both signal phase and amplitude. Typically, networks of ground based GNSS receivers are used to derive those maps, but it inevitably leads to sparse coverage. 

In order to mitigate this weakness, the current study proposes to add original data points based on the DORIS system. DORIS (Doppler Orbitography by Radiopositioning Integrated by Satellite) is a French orbitography system, developed primarily for altimetric purposes by the Centre National d’Etudes Spatiales (CNES), the Institut National de l’information géographique et forestière (IGN) and the Groupe de Recherche de Géodésie Spatiale (GRGS). It consists of a network of around sixty ground-based beacons emitting a radio-frequency signal at 400 MHz and 2 GHz. The on-board receivers (on 9 civilian satellites as of January 2024) then performs Doppler shift measurements that allow precise orbit determination.  

Despite a lower data rate (0,1 Hz instead of 1 Hz for the GNSS) and a lower number of satellites, DORIS can add valuable information where there is no GNSS receivers, or by taking advantage of its geometry, in particular with polar satellites. In this study, we will explore to what extent it is possible to define scintillation proxies based on DORIS data losses, phase signal degradation, or power signal attenuation, by a comparison to a scintillation data base from GNSS measurements. Eventually, we will discuss whether the challenging near-real time basis delay is achievable. 

How to cite: Cherrier, M. and Yaya, P.: Contribution of DORIS System to Global Ionospheric Scintillation Mapping, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10799, https://doi.org/10.5194/egusphere-egu24-10799, 2024.

EGU24-10847 | Posters on site | ST4.4

Faraday cup instrument for the solar wind monitoring at 0.9 AU — HENON mission 

Lubomír Přech, Jana Šafránková, Zdeněk Němeček, Ivo Čermák, Tereza Ďurovcová, Maria Federica Marcucci, Monica Laurenza, and Davide Calgano

The HEliospheric pioNeer for sOlar and interplanetary threats defeNce (HENON) mission funded by the Italian Space Agency has recently advanced to implementation (Phase C). The HENON 12U cubesat is expected to reach a Distant Retrograde Orbit (DRO) of the Sun–Earth system before the end of this decade. For several months it will stay about ≈ 0.1 AU in front of the Earth, providing thus a unique vantage point for the in-situ solar wind monitoring and allowing to send space weather alerts several hours before the related causal geoeffective structures can reach the Earth. The payload of the mission consists of the high-resolution radiation monitor (REPE), magnetometer (MAGIC), and the Faraday cup based solar wind monitor (FCA), provided by the Italian, Finnish, UK, and Czech consortium members.

In this contribution we focus to the description of latter sensor — the Faraday Cup Analyzer (FCA), developed at Charles University as a simple and robust sensor for long-term monitoring of the basic solar wind parameters — density, velocity and temperature. We describe the overall instrument design, discuss many important technical aspects of the development including a computer modeling of the most important parts — Faraday cups (FC). We report on results of testing of an FCA development model with newly designed FC sensors, the instrument operation modes and future telemetry data products. As the HENON mission is greatly constrained with limited spacecraft telemetry, we also discuss the data strategy and on-board data processing allowing maximum scientific income and satisfying the mission requirements.

How to cite: Přech, L., Šafránková, J., Němeček, Z., Čermák, I., Ďurovcová, T., Marcucci, M. F., Laurenza, M., and Calgano, D.: Faraday cup instrument for the solar wind monitoring at 0.9 AU — HENON mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10847, https://doi.org/10.5194/egusphere-egu24-10847, 2024.

EGU24-10862 | Orals | ST4.4

Improving the REleASE solar proton forecasting capabilities with evidence of particle escape from the Sun: HESPERIA REleASE +  

Olga E. Malandraki, Arik Posner, Michalis Karavolos, Kostas Tziotziou, Fanis Smanis, Monica Laurenza, Janet Barzilla, Edward Semones, Kathryn Whitman, M. Leila Mays, Chinwe Didigu, Christopher J. Stubenrauch, Bernd Heber, Patrick Kuehl, Milan Maksimovic, Vratislav Krupar, and Nikolas Milas

Providing reliable forecasts of Solar Energetic Particle (SEP) events is mandatory for human spaceflight beyond low-Earth orbit, especially outside the Earth's magnetosphere. High-energy SEPs are tracked because they penetrate deeper into the terrestrial atmosphere and contribute to the radiation dose aboard spacecraft specifically over Canada and the Southern Indian Ocean, due to the tilt of the Earth on its axis. Based on the Relativistic Electron Alert System for Exploration (REleASE) forecasting scheme], the HESPERIA REleASE product was developed by the HESPERIA H2020 project (Project Coordinator: Dr. Olga Malandraki) and generating real-time predictions of the proton flux (30-50 MeV) at L1, making use of relativistic and near-relativistic electron measurements by the SOHO/EPHIN and ACE/EPAM experiments, respectively. The HESPERIA REleASE tools are operational through the Space Weather Operational Unit of the National Observatory of Athens, accessible through the dedicated website (http://www.hesperia.astro.noa.gr). HESPERIA REleASE has attracted attention from various space organizations (e.g., NASA/CCMC, SRAG), due to the real-time, highly accurate and timely performance offered. ESA selected the HESPERIA REleASE products that were integrated and provided through the ESA Space Weather (SWE) Service Network (https://swe.ssa.esa.int/noa-hesperia-federated) under the Space Radiation Expert Service Center (R-ESC). Solar cycle 25 solar radiation storms successfully predicted by HESPERIA REleASE are presented and discussed. Moreover, we present an innovative upgrade implemented, namely HESPERIA REleASE+, that is using the novel approach of combining for the first time real-time type III solar radio burst observations by the STEREO S/WAVES instrument, thus incorporating clear evidence of particle escape from the Sun, within the HESPERIA REleASE system. To this end, a robust automated algorithm has been developed for the real-time identification and classification of Type III radio burst characteristics, related to intense SEP events at Earth’s orbit. This new implementation leads to a substantial step forward in improving the accuracy and reduction of false alarms.

How to cite: Malandraki, O. E., Posner, A., Karavolos, M., Tziotziou, K., Smanis, F., Laurenza, M., Barzilla, J., Semones, E., Whitman, K., Mays, M. L., Didigu, C., Stubenrauch, C. J., Heber, B., Kuehl, P., Maksimovic, M., Krupar, V., and Milas, N.: Improving the REleASE solar proton forecasting capabilities with evidence of particle escape from the Sun: HESPERIA REleASE + , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10862, https://doi.org/10.5194/egusphere-egu24-10862, 2024.

EGU24-11055 | Orals | ST4.4 | Highlight

Digitized continuous magnetic recordings for the August/September 1859 storms from London, UK 

Ciaran Beggan, Ellen Clarke, Ewelina Lawrence, Eliot Eaton, John Williamson, Keitaro Matsumoto, and Hisashi Hayakawa

Dedicated scientific measurements of the strength and direction of the Earth's magnetic field began at Greenwich and Kew observatories in London, UK, in the middle of the 19th century. Using advanced techniques for the time, collimated light was focussed onto mirrors mounted on free-swinging magnetized needles which reflected onto photographic paper, allowing continuous analogue magnetograms to be recorded. By good fortune, both observatories were in full operation during the so-called Carrington storm in early September 1859 and its precursor storm in late August 1859. Based on digital images of the magnetograms and information from the observatory yearbooks and scientific papers, it is possible to scale the measurements to SI units and extract quasi-minute cadence spot values. However, due to the magnitude of the storms, the periods of the greatest magnetic field variation were lost as the traces moved off-page. We present the most complete digitized magnetic records to date of the ten-day period from 25th August to 5th September 1859 encompassing the Carrington storm and its lesser recognised precursor on the 28th August. We demonstrate the good correlation between observatories and estimate the instantaneous rate of change of the magnetic field.

How to cite: Beggan, C., Clarke, E., Lawrence, E., Eaton, E., Williamson, J., Matsumoto, K., and Hayakawa, H.: Digitized continuous magnetic recordings for the August/September 1859 storms from London, UK, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11055, https://doi.org/10.5194/egusphere-egu24-11055, 2024.

EGU24-11417 | Posters on site | ST4.4

Predicting GOES Electron Fluxes With Comprehensive Inner Magnetosphere-Ionosphere (CIMI) Model for Different Types of Geomagnetic Storms 

Natalia Buzulukova, Juan Rodriguez, Brian Kress, Mei-Ching Fok, Lauri Holappa, Rob Redmon, and Artem Smirnov

The Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model has proved to be an effective tool to understand dynamics of charged particles in the Earth's inner magnetosphere. The CIMI model can predict fluxes of radiation belt electrons, ring current particles, cold plasmaspheric population as a function of solar wind parameters, indices, equatorial radial distance, local time, energy and pitch-angle information (for radiation belts/ring current). For electrons, the CIMI model solves advection-diffusion equation combined with statistical models for chorus wave intensity and tabulated diffusion coefficients to predict radiation belt fluxes. An important part of the CIMI model is calculation of the electric field in the inner magnetosphere that is self-consistent with the ring current pressure distribution. For this study, we use the CIMI model to simulate GOES electron fluxes in the energy range 40-450 keV. Fluxes in this energy range are highly dynamic and their prediction is very important for complete space weather analysis. Additional motivation for understanding the dynamics of this energy range is demonstrated by recent findings that establish the population of electrons with energies of 100–200 keV in GEO orbit as a new class of previously neglected space weather hazards. We simulate CIMI electron fluxes for ~20 CIR-type geomagnetic storms and ~20 CME-type geomagnetic storms, and study both the model response and GOES fluxes as a function of the drivers (storm type, IMF Bz , Vx, dynamic pressure) and the local time sector. Finally, we evaluate the model's performance in terms of statistical metrics and propose ways to improve the model's predictions.

How to cite: Buzulukova, N., Rodriguez, J., Kress, B., Fok, M.-C., Holappa, L., Redmon, R., and Smirnov, A.: Predicting GOES Electron Fluxes With Comprehensive Inner Magnetosphere-Ionosphere (CIMI) Model for Different Types of Geomagnetic Storms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11417, https://doi.org/10.5194/egusphere-egu24-11417, 2024.

EGU24-11750 | Posters on site | ST4.4

A comprehensive study from the Sun to the Earth of the Space Weather event starting on the 6 September 2017 

Monica Laurenza on behalf of the CAESAR Team

It is well known that Space Weather events can have a profound impact on our technology-dependent society. On September 6, 2017, a powerful Space Weather event originated on the Sun in the active region 12673 located at 9 degrees North latitude and 42 degrees West longitude.  An X9.3 class flare was produced, peaking at 12:02 UT, and was associated with a powerful eruptive coronal mass ejection and the emission of solar energetic particles. Correspondingly, several phenomena were observed in the interplanetary space and Earth’s environment on September 7: a shock passage at 22.58 UT associated with an energetic particle enhancement, followed by magnetospheric compression, plasmasphere density depletion, ionospheric storm and intensification of convection cells, and a Forbush decrease in the cosmic ray intensity. Here we provide a comprehensive understanding of the event, encompassing the whole chain of phenomena occurred from the Sun to the Earth. We explore the causes and evolution the Space Weather event and evaluate effects on technological systems as well as  implications for future space weather research. 

How to cite: Laurenza on behalf of the CAESAR Team, M.: A comprehensive study from the Sun to the Earth of the Space Weather event starting on the 6 September 2017, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11750, https://doi.org/10.5194/egusphere-egu24-11750, 2024.

EGU24-13327 | ECS | Orals | ST4.4

Operational Space Weather Modelling in the Bergen-Imperial Global Geospace (BIGG) Project 

Adrian LaMoury, Mike Heyns, Jonathan Eastwood, Norah Kwagala, and Jon-Thøger Hagen

In order to better safeguard society and infrastructure from space weather hazards, improved forecasting capabilities are required. To maximise the efficiency of mitigation strategies, forecasting products must not only be accurate, but also timely and tailored to end-user needs. For understanding and predicting the behaviour of the near-Earth space environment in changing solar wind conditions, physics-based modelling is extremely powerful, though often comes at considerable computational expense. The Bergen-Imperial Global Geospace (BIGG) project is an ongoing collaborative effort to provide new space weather forecasting capabilities to the ESA space weather service network via the use of two 3D magnetohydrodynamic (MHD) magnetosphere models, GorgonOps and the Space Weather Modelling Framework (SWMF). Solar wind observations as measured in situ at L1 will be continuously and automatically ingested as simulation inputs, with minimal human intervention. Both models have been optimised such that they are able to run in faster than real time, using only modest computational resources, delivering bespoke forecasting products to the end-user community via a web portal and API in a timely fashion. This multi-model approach will provide forecast diversity and redundancy to ensure continuous and reliable service provision to Europe and beyond.

How to cite: LaMoury, A., Heyns, M., Eastwood, J., Kwagala, N., and Hagen, J.-T.: Operational Space Weather Modelling in the Bergen-Imperial Global Geospace (BIGG) Project, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13327, https://doi.org/10.5194/egusphere-egu24-13327, 2024.

EGU24-13486 | Orals | ST4.4

The Space Weather Research on Coronal Mass Ejections Required Before Operational Sub-L1 Monitors 

Noé Lugaz, Florian Regnault, Sahanaj Banu, Nada Al-Haddad, Bin Zhuang, Christina Lee, Charles J. Farrugia, Christian Möstl, Reka M. Winslow, Emma Davies, Camilla Scolini, Wenyuan Yu, and Toni Galvin

In-situ measurements from the Sun-Earth Lagrangian L1 point typically provide a 20-minute to 1-hour advanced warning of incoming interplanetary (IP) shocks, magnetic clouds before impact at the nose of Earth's magnetopause. Sub-L1 monitors may provide measurements sunward of the L1 point to improve the lead times for such transients to several hours, and various mission architecture have been proposed for more than 25 years. Because CMEs and shocks do not propagate exactly radially, the location of such a monitor with respect to the Sun-Earth line is a key parameter to take into account when designing such missions. Here, we highlight some recent results and measurements of CMEs that show that small angular separations may result in drastic differences in the CME properties measured by two spacecraft, and examples showing that CME evolution over a few hours may differ significantly from the average evolution as obtained from statistical studies over several decades. We highlight how a pathfinder mission is required to better understand the variation of properties within CMEs on moderate scales and the evolution of CMEs over a few hours. Such an improved knowledge will then allow for a dedicated fleet of operational monitors that will improve the lead time of space weather forecasting without a loss of accuracy

How to cite: Lugaz, N., Regnault, F., Banu, S., Al-Haddad, N., Zhuang, B., Lee, C., Farrugia, C. J., Möstl, C., Winslow, R. M., Davies, E., Scolini, C., Yu, W., and Galvin, T.: The Space Weather Research on Coronal Mass Ejections Required Before Operational Sub-L1 Monitors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13486, https://doi.org/10.5194/egusphere-egu24-13486, 2024.

EGU24-14525 | ECS | Posters on site | ST4.4

Statistics of the extreme events with extreme value theory 

Si Chen, Hong Yuan, and Yong Wei

Measuring the probability of extreme space weather events poses a challenge due to their infrequency. However, these rare events significantly and extensively impact various facilities in modern society. Extreme space weather events from the Sun have the potential to push the magnetosphere into an extreme state, where electromagnetic fields and particle environments behave differently than predicted by conventional theory, potentially causing more severe impacts than anticipated. In this study, we applied Extreme Value Theory to geomagnetic indices (such as the AE index, Aa index) derived from ground-based magnetometer observations spanning various solar cycles. We obtained the return levels of the indices with different return periods and identified an upper bound for the time series. Diligent precautions are necessary to mitigate the consequences of such extreme events, and surpassing the upper limit becomes increasingly challenging over time.

How to cite: Chen, S., Yuan, H., and Wei, Y.: Statistics of the extreme events with extreme value theory, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14525, https://doi.org/10.5194/egusphere-egu24-14525, 2024.

EGU24-15028 | Posters on site | ST4.4

How well does 3DCORE perform at fitting flux rope signatures in real-time? 

Ute Amerstorfer, Hannah Rüdisser, Andreas Weiss, and Christian Möstl

The 3D coronal rope ejection (3DCORE) method has been used to fit magnetic fields of CME flux ropes to in situ observations. Its assumed Gold-Hoyle-like flux rope has an elliptical cross-section and expands self-similarly, thereby staying always attached to the Sun. An approximate Bayesian computation sequential Monte Carlo algorithm performs the fitting and allows us to get error estimates of the model parameters. 

Extending our previous studies, we investigate the ability of 3DCORE to fit the magnetic field of a flux rope in real time, when only the first hours of an observation are available. Therefore, we use past events mimicking a possible real-time application, but also any real-time events possibly happening. If performing well, this real-time application of 3DCORE can further advance the efforts of space weather prediction.

 

How to cite: Amerstorfer, U., Rüdisser, H., Weiss, A., and Möstl, C.: How well does 3DCORE perform at fitting flux rope signatures in real-time?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15028, https://doi.org/10.5194/egusphere-egu24-15028, 2024.

EGU24-16590 | ECS | Posters on site | ST4.4 | Highlight

Automated detection and tracking of CMEs using HI instruments 

Maike Bauer, Justin LeLouedec, Tanja Amerstorfer, and Jackie Davies

Timely and accurate prediction of coronal mass ejections (CMEs) is vital for mitigating the potential impact of severe space weather events on critical infrastructures. Currently, manual detection and tracking of CMEs as they traverse the heliosphere are the norm. This presentation introduces an innovative approach: the development and implementation of a machine learning algorithm for automatic detection and tracking of CMEs, leveraging data from various heliospheric imager (HI) instruments. The wealth of active spacecraft equipped with HI instruments provides a unique opportunity to train the algorithm using diverse datasets.

This work gains significance in light of the upcoming launch of Vigil, a space weather monitor scheduled for deployment in the early 2030s at the L5 point. Vigil will continuously observe and provide real-time HI observations along the Sun-Earth line. Our presentation showcases preliminary outcomes from an automated CME detection and tracking algorithm, demonstrating its effectiveness with training on STEREO-HI data. We also discuss potential future steps and challenges in the development and testing of this algorithm, emphasizing its role in advancing operational space weather prediction capabilities, especially in anticipation of the Vigil mission.

How to cite: Bauer, M., LeLouedec, J., Amerstorfer, T., and Davies, J.: Automated detection and tracking of CMEs using HI instruments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16590, https://doi.org/10.5194/egusphere-egu24-16590, 2024.

EGU24-17944 | Orals | ST4.4

ESA Swarm mission after 10 years in Space: new opportunities through enhanced processors and data quality 

Roberta Forte, Enkelejda Qamili, Nicola Comparetti, Lars Tøffner-Clausen, Stephan Buchert, Johnathan Burchill, Christian Siemes, Alessandro Maltese, Anna Mizerska, María José Brazal Aragón, Lorenzo Trenchi, Elisabetta Iorfida, Irene Cerro Herrero, Berta Hoyos Ortega, Giuseppe Albini, Antonio De la Fuente, and Anja Stromme

On 22nd November 2023 Swarm ESA’s Earth Explorer mission celebrated 10 years in Space, characterizing Earth’s geomagnetic, ionospheric and electric fields, for a better understanding of our planet’s interior and its environment. After a decade in orbit, the mission is still in excellent shape and continues to contribute to a wide range of scientific studies, from the core of our planet, via the mantle and the lithosphere, to the ionosphere and interactions with Solar wind, opening the door for many innovating applications largely beyond its original scope.

Moreover, the processing algorithms have been continuously improved since the beginning of the mission, to cope with the evolving needs of the scientific community, to keep providing excellent quality data and to maintain good instruments performances.

In April 2023 a “Fast” processing chain has been transferred to operations, providing Swarm L1B products with a minimum delay respect to the acquisition. This Fast data production adds significant value to Swarm mission’s scientific purposes and applications, making it eligible for monitoring Space Weather phenomena, modelling and nowcasting the evolution of several geomagnetic and ionospheric events.

This work provides an overview of the Swarm enhanced data processing chain, instruments performances, Fast chain applications and upcoming evolutions, together with other innovative Swarm-based data products and services.

How to cite: Forte, R., Qamili, E., Comparetti, N., Tøffner-Clausen, L., Buchert, S., Burchill, J., Siemes, C., Maltese, A., Mizerska, A., Brazal Aragón, M. J., Trenchi, L., Iorfida, E., Cerro Herrero, I., Hoyos Ortega, B., Albini, G., De la Fuente, A., and Stromme, A.: ESA Swarm mission after 10 years in Space: new opportunities through enhanced processors and data quality, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17944, https://doi.org/10.5194/egusphere-egu24-17944, 2024.

EGU24-17954 | Orals | ST4.4

Ionospheric Scintillation Nowcasting and Forecasting for Civil Aviation 

Philippe Yaya, Roiya Souissi, Marie Cherrier, and Ali Naouri

The International Civil Aviation Organization (ICAO) has set up a space weather service for monitoring and raising alerts in case of moderate or severe potential impact on aviation, and covering three domains: GNSS, Radiation and HF Communications. This service is operational since November 2019 and is working in a bi-weekly rotation of four global centers: SWPC (US Space Weather Prediction Center), PECASUS (consortium of 9 European States), CRC (China-Russia Consortium) and ACFJ (Australia-Canada-France-Japan). CLS (Collecte Localisation Satellites), a member of ACFJ, is a subsidiary of the French Space Agency and responsible for delivering near real-time ionospheric scintillation maps. The input data is based on a worldwide network of GNSS receivers, composed of various regional and global networks. The work presented here summarizes the adopted algorithms and pre-processing tasks leading to generate the nowcast maps. The results of a validation work are shown (comparison of indices from geodetic receivers and scintillation monitors) as well as a focus on severe events and their effect on aviation. Finally, taking advantage of a 4-years long data base, the status of a forecasting scintillation model is presented, taking care of separating the EPBs (Equatorial Plasma Bubbles) and geomagnetic storms origins.

How to cite: Yaya, P., Souissi, R., Cherrier, M., and Naouri, A.: Ionospheric Scintillation Nowcasting and Forecasting for Civil Aviation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17954, https://doi.org/10.5194/egusphere-egu24-17954, 2024.

EGU24-17975 | Posters on site | ST4.4 | Highlight

Operational SSUSI Aurora Forecast Model  

Syau-Yun Hsieh, Yongliang Zhang, Robert Schaefer, and Larry Paxton

Particle precipitation in the auroral oval serves as an important connection between the magnetosphere and ionosphere/atmosphere.  It is an important source of energy for the high-latitude upper atmosphere.  Particle precipitation not only creates extra ionization in the high-latitude ionosphere which leads to absorption and disturbances in radio communication, but also enhances the Joule heating by creating the Hall and Pedersen conductivity which alters the thermospheric convection and composition and further causes the global ionospheric disturbances.   To accurately characterize the auroral region energy inputs and conductivity is essential for improving the current capability for nowcasting and forecasting the ionospheric conditions in the high latitude region for space weather. The SSUSI Aurora Forecast Model is an FUV-based aurora forecast model.  It has been used operationally for predicting the global auroral quantities using the input remote-sensing ultraviolet measurements from the DMSP/SSUSI instruments.  The model predicts the equatorward boundary of auroral oval and precipitating the electron energy flux and mean energy estimated based on the empirical GUVI global model for up to 1 day or 15 DMSP orbits in advance.  We present the current implementation, capability and forecast results of this operational forecast model.  We will also discuss the current improvement and future development.

How to cite: Hsieh, S.-Y., Zhang, Y., Schaefer, R., and Paxton, L.: Operational SSUSI Aurora Forecast Model , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17975, https://doi.org/10.5194/egusphere-egu24-17975, 2024.

The Near Earth Space Environment is a complex and interconnected system of systems, and the home of a multitude of physical processes all contributing to space weather and space climate effects, and hence collaboration across traditional boundaries is essential in order to progress in our understanding of and our capability to predict Space Weather.  

The ESA Swarm Earth Explorer mission, launched 22. September 2013 has completed almost a solar cycle in orbit and is in its nature a true system science mission in its endeavor to unravel our planets invisible shield on a magnetic journey from the Earth’s core to the magnetosphere and nearly everything in-between.

In this presentation we will highlight both the direct contributions the Swarm mission has had and continues to have for the space weather community through constantly evolving products and services, but also how it has acted as a catalyst to help utilize other data sources in order to enhance our understanding of space weather processes.

How to cite: Stromme, A.: How the ESA Swarm mission can contribute to Space Weather and Space Climate , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18152, https://doi.org/10.5194/egusphere-egu24-18152, 2024.

EGU24-20550 | Posters on site | ST4.4

Predicting geo-effectiveness two days prior to CME impact with EUHFORIA 

Stefaan Poedts, Senne Doumen, Anwesha Maharana, Peter Wintoft, and Tinatin Baratashvili

The EUropean Heliospheric FORecasting Information Asset (EUHFORIA, Pomoell and Poedts, 2018), a physics-based and data-driven heliospheric and CME propagation model can predict the solar wind plasma and magnetic field conditions at Earth. It contains several flux-rope CME models, such as the simple spheromak models and the more advanced FRi3D and toroidal CME models. This enables the prediction of the sign and strength of the magnetic field components upon the arrival of the CME at Earth and, thus, the geo-effectiveness of the CME impact. EUHFORIA has been coupled to several global magnetosphere models like OpenGGCM, GUMICS-4, and Gorgon-Space. In addition, the synthetic data at L1 (from the EUHFORIA simulation) can be used as input for empirical models and neural networks to predict the geomagnetic indices like Disturbance-storm-time (Dst) or Kp that quantify the impact of the magnetized plasma encounters on Earth’s magnetosphere. Hence, we also coupled EUHFORIA to empirical models (Obrien and McPherron, 2000b, and Newell et al, 2006) and machine learning (NARMAX, and the models from Wintoft et al. (2017 and 2021)) based models to predict the geomagnetic indices. We then compare the results of these models to observational data to evaluate their performance in predicting the geo-effect indices. To quantify these comparisons, we use the advanced dynamic time warping method. Since we use synthetic data from the EUHFORIA simulations, we can obtain the input parameters for running the geomagnetic indices models two to three days in advance, unlike the 60-90 minutes lead time of the real-time measurements. 

We perform ensemble modelling considering the L1 monitor precision in its orbit as well as the uncertainty in the initial CME parameters (longitude and latitude) at launch, for error quantification. This is done by evaluating the geomagnetic index models using synthetic data from the virtual satellites around L1 in EUHFORIA’s simulation domain. In addition, we also investigate the impact of the spatio-temporal resolution of EUHFORIA output in forecasting the geomagnetic indices, exploiting the adaptive mesh refinement feature in ICARUS (Baratashvili et al., 2022). Overall, this study validates various space weather forecasting model chains and checks the best compatibility and predictive capabilities using EUHFORIA data for operational space weather forecasting.  

How to cite: Poedts, S., Doumen, S., Maharana, A., Wintoft, P., and Baratashvili, T.: Predicting geo-effectiveness two days prior to CME impact with EUHFORIA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20550, https://doi.org/10.5194/egusphere-egu24-20550, 2024.

EGU24-20576 | Posters on site | ST4.4

Linking pre-flare active region parameters to Flare, CME and SEP properties 

Maher Dayeh and Radoslav Bučik

Solar flares, Coronal Mass Ejections (CMEs), and associated Solar Energetic Particles (SEPs) play crucial roles in influencing space weather in the vicinity of Earth and beyond. Forecasting these events requires prior knowledge and understanding of the physical mechanisms driving these phenomena. Although some CMEs and flares are strongly associated with intense SEPs, there are instances where little or no SEP connection is evident. This lack of consistent correlation between observed SEPs at 1 AU and their origins near the Sun is primarily due to the complex interplanetary environment that governs SEP generation, acceleration, and transport. Currently, there is no reliable and consistent method for long-term forecasting (spanning hours to days) of SEP properties, and efforts to develop such forecasting techniques are ongoing. The Space Weather Helioseismic and Magnetic Imager (HMI) Active Region Patches (SHARP) provide information about the magnetic properties (e.g., helicity, strength, and gradient) of solar active regions and pre-flaring activity.  In this work, we examined the connection between the characteristics of 21 large gradual SEP events affecting the Earth environmentand and their associated SHARP parameters. Specifically, we investigated the relationship between SEP peak intensities at ~10 MeV and ~50 MeV, CME speed, X-ray flare, and the SHARP parameters. Our findings reveal consistent and stable correlations, both positive and negative, between average SHARP parameters and each of the analyzed properties within the 24 hours leading up to the flare onset. These results offer evidence that SHARP parameters could significantly enhance the prediction of space weather events.

How to cite: Dayeh, M. and Bučik, R.: Linking pre-flare active region parameters to Flare, CME and SEP properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20576, https://doi.org/10.5194/egusphere-egu24-20576, 2024.

EGU24-5106 | ECS | Posters on site | ST4.6

Relation between Latitude-dependent Sunspot Data and Near-Earth Solar Wind Speed 

qirong Jiao, wenlong liu, dianjun zhang, and jinbin cao

Solar wind is important for the space environment between the Sun and the Earth and varies with the sunspot cycle, which is influenced by solar internal dynamics. We study the impact of latitude-dependent sunspot data on solar wind speed using the Granger causality test method and a machine-learning prediction approach. The results show that the low-latitude sunspot number has a larger effect on the solar wind speed. The time delay between the annual average solar wind speed and sunspot number decreases as the latitude range decreases. A machine-learning model is developed for the prediction of solar wind speed considering latitude and time effects. It is found that the model performs differently with latitude-dependent sunspot data. It is revealed that the timescale of the solar wind speed is more strongly influenced by low-latitude sunspots and that sunspot data have a greater impact on the 30 day average solar wind speed than on a daily basis. With the addition of sunspot data below 7.°2 latitude, the prediction of the daily and 30 day averages is improved by 0.23% and 12%, respectively. The best correlation coefficient is 0.787 for the daily solar wind prediction model. 

How to cite: Jiao, Q., liu, W., zhang, D., and cao, J.: Relation between Latitude-dependent Sunspot Data and Near-Earth Solar Wind Speed, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5106, https://doi.org/10.5194/egusphere-egu24-5106, 2024.

EGU24-12493 | Posters on site | ST4.6 | Highlight

Improved GNSS receiver bias estimation using a neural-network based total electron content model 

Mainul Hoque, Marjolijn Adolfs, and Luisa Riaño Salamanca

With the availability of fast computing machines, as well as the advancement of machine learning techniques and Big Data algorithms, the development of a more sophisticated total electron content (TEC) model featuring large scale ionospheric irregularities and anomalies is possible. We recently developed a fully connected neural network model trained with Global Ionospheric Maps (GIMs) data from the last two solar cycles. The model can successfully reconstruct ionospheric features that are not always visible such as Nighttime Winter Anomaly (NWA) which is only visible in the Northern Hemisphere at the American sector and in the Southern Hemisphere at the Asian longitude sector during low solar activity, winter and local night-time conditions. The NN based TEC model inherits also other features such as the distribution of Mid-latitude Ionospheric Trough (MIT) and the longitudinal variation of the Equatorial Ionization Anomaly (EIA) features. Being motivated from the performance of the NN based TEC model in ionosphere reconstruction we applied the model for differential code bias (DCB) estimation for a network of ground GNSS receivers. The investigation shows that the receiver DCBs can be accurately computed by the NN-based TEC model. The obtained accuracies are comparable to those obtained by the conventional method of DCB estimation by fitting GNSS TEC data to the ionospheric basis function represented by spherical harmonics or other approaches. It is expected that the application of NN based TEC model for GNSS receiver bias estimation will simplify the operational procedures for near real-time ionosphere monitoring without losing its accuracy.

How to cite: Hoque, M., Adolfs, M., and Salamanca, L. R.: Improved GNSS receiver bias estimation using a neural-network based total electron content model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12493, https://doi.org/10.5194/egusphere-egu24-12493, 2024.

Using the electron density (Ne) observations from the Defense Meteorological Satellite Program (DMSP), and Constellation Observing Systems for Meteorology, Ionosphere, and Climate mission (COSMIC) and simulations from the Thermosphere Ionosphere Electrodynamic General Circulation Model (TIEGCM), we investigate the dynamic evolution of the polar tongue of ionization (TOI) from double to single structures at different altitudes during a geomagnetic storm. The modeled Ne depicted that double and single TOIs occurred at altitudes above 300 km, respectively. During the northward turning of IMF Bz, the afternoon TOI disappeared and the morning TOI was reduced. The plasma transport due to neutral winds and ambipolar diffusion facilitated (prevented) the depletion of plasma density of the morning TOI at 300 (500) km, with a relative contribution of 42.8% and 28.6% (-15.4% and -76.9%), respectively. Downward E × B drifts led to an enhancement/reduction of plasma density in the SED region in the lower/upper ionosphere. During the duskward turning of IMF By, the morning TOI could be mostly attributed to the anti-sunward plasma drifts (75.8% at 300 km, 100% at 500 km), with a relatively stronger role of the zonal component than that of meridional E × B drifts. The upward E × B drifts were important/ignorable in the upper/lower ionosphere. Both the neutral winds and ambipolar diffusion resulted in an accumulation of plasma density of the morning TOI at 300 km indirectly (24.2%), however, their roles were minor at 500 km.

How to cite: song, H.: Dynamics of the tongue of ionizations at different altitudes during the geomagnetic storm on September 7, 2015, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14780, https://doi.org/10.5194/egusphere-egu24-14780, 2024.

EGU24-15325 | ECS | Posters on site | ST4.6

Predicting Global Ionosphere in Three Dimensions: Integrating Data Assimilation with Convolutional Neural Networks 

Chalachew Kindie Mengist and Kyong-Hwan Seo

In this study, we present a novel approach to improve ionosphere prediction by combining the Ionospheric Data Assimilation Four-Dimensional (IDA4D) algorithm with Convolutional Neural Networks (CNNs). The IDA4D algorithm constructs a three-dimensional global electron density by assimilating ground-based GPS slant total electron content (STEC), radio occultation STEC, and radio occultation NmF2 data into the IRI model. The IDA4D outputs are fed into CNNs to learn spatiotemporal patterns. Results are validated with ionosonde and CODE TEC data, demonstrating significant improvements and reducing the root-mean-square error (RMSE) of Nmf2 and vertical TEC by 34% and 51%, respectively, compared to the IRI model. Furthermore, the IDA4D technique successfully reconstructed storm time enhancement of the northern crest equatorial ionization anomaly during late evening hours, resulting from upward and northward plasma transport. The combination of IDA4D and CNNs predicts a three-dimensional electron density more accurately than the IRI model for up to two days.

How to cite: Mengist, C. K. and Seo, K.-H.: Predicting Global Ionosphere in Three Dimensions: Integrating Data Assimilation with Convolutional Neural Networks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15325, https://doi.org/10.5194/egusphere-egu24-15325, 2024.

EGU24-19119 | ECS | Posters on site | ST4.6

A Long Short-Term Memory Neural Network for predicting Global Ionospheric Total Electron Content 24 hours ahead 

Marjolijn Adolfs, Mohammed Mainul Hoque, and Yuri Y. Shprits

In this study a long short-term memory (LSTM) network architecture is utilized to make 24-hour ahead global ionospheric total electron content (TEC) predictions. The preceding 3-day historical TEC data, geographic longitude and latitude, universal time and day of year are used as model input parameters. We investigated the LSTM performance using proton density, solar wind forcing parameters and interplanetary magnetic field components as external model drivers. Other drivers such as ionospheric disturbance index SYM-H, solar radio flux index F10.7 and geomagnetic activity index Hp30 were included in the investigations as well. The above-mentioned investigated parameters were excluded in the final model development since they did not improve the model’s accuracy significantly. The model was trained using the rapid UQRG global ionosphere maps (GIMs) from the Universitat Politècnica de Catalunya (UPC) comprising a period of two solar cycles (1998-2020). The model’s performance was analyzed for a test dataset which was excluded from the training data and contained quiet and geomagnetic storm days together with a low and high solar activity period. In order to see the model’s performance for near real-time (RT) applications, the model was tested using the combined RT products of the international GNSS service (IGS), e.g. IRTG GIMs. The performance of the LSTM-based model was compared to another neural network (NN)-based method (feed forward NN) and the Neustrelitz TEC model (NTCM). The LSTM-based model was outperforming the two models for both cases, e.g. using the IRTG or UQRG maps as an input for the historical TEC data.

How to cite: Adolfs, M., Hoque, M. M., and Shprits, Y. Y.: A Long Short-Term Memory Neural Network for predicting Global Ionospheric Total Electron Content 24 hours ahead, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19119, https://doi.org/10.5194/egusphere-egu24-19119, 2024.

EGU24-2928 | Orals | ST4.7

Long-term Solar Spectral Irradiance Observations by the TSIS-1 Spectral Irradiance Monitor 

Erik Richard, Odele Coddinton, Dave Harber, Peter Pilewskie, and Tom Woods

The NASA’s Total and Spectral Solar Irradiance Sensor (TSIS-1) launched on December 15th, 2017 and was integrated on the International Space Station (ISS) to measure long-term total solar irradiance (TSI) and solar spectral irradiance (SSI). The direct measurement of the SSI is made by the LASP Spectral Irradiance Monitor (SIM) and provides data essential to interpreting how the Earth system responds to solar spectral variability. Extensive advances in TSIS-1 SIM instrument design and new SI-traceable spectral irradiance calibration techniques have resulted in improved absolute accuracy with uncertainties of less than 0.5% over the continuous 200 to 2400 nm spectral range. Furthermore, improvements in the long-term spectral stability corrections provide lower trend uncertainties in SSI variability from those of the previous SORCE SSI instruments. We present the early mission results of the TSIS-1 SIM SSI observations for the first 5 years of operations – a time-period that includes the descending phase of solar cycle 24, the last solar minimum, and the ascending phase of solar cycle 25. Comparisons are made to previous spectral measurements both in the absolute scale of the solar spectrum and the time dependence of the SSI variability. The TSIS-1 SIM SSI spectrum shows lower IR irradiance (by as much as 6% near 2400 nm) and small visible irradiance increases (~0.5%) from the previous ATLAS3 and WHI reference solar spectra, but more consistent agreement with recent SCIAMACHY and SOLAR2 reanalysis results. We also show initial comparisons to current NRLSSI2 and SATIRE-S SSI model results both for short-term (solar rotation) spectral variability and, for the first time, the longer-term (near half solar cycle) spectral variability across the solar spectrum from the UV to the IR.

How to cite: Richard, E., Coddinton, O., Harber, D., Pilewskie, P., and Woods, T.: Long-term Solar Spectral Irradiance Observations by the TSIS-1 Spectral Irradiance Monitor, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2928, https://doi.org/10.5194/egusphere-egu24-2928, 2024.

EGU24-5966 | Posters on site | ST4.7

The JSTIM-DARA  product derived from the TSI Observations Recorded by the FY3E/JTSIM/DARA Radiometer 

Jean-Philippe Montillet, Wolfgang Finsterle, Margit Haberreiter, Daniel Pfiffner, Ping Zhu, Duo Wu, Silvio Koller, Xin Ye, Dongjun Yang, Wei Fang, Jin Qi, and Peng Zhang

Since the late 1970s, successive satellite missions have been monitoring solar activity and recording Total Solar Irradiance (TSI) data. The Digital Absolute
Radiometer (DARA) on board the Chinese FY3E spacecraft was launched on July 4, 2021, and  has since been recording TSI observations. Here, we analyze these observations and assess the performance of DARA, including sensor degradation of 5 ppm after 2 years in orbit, resulting from exposure to ultraviolet and extreme ultraviolet radiation. Comparing the new dataset’s mean values with observations from active  instruments on other spacecraft (i.e., PMO6 on board the VIRGO/SOHO and the TIM/TSIS), along with the Solar Irradiance Absolute Radiometer (SIAR) also on board  FY3E/JTSIM, we find that DARA observations closely align with TIM/TSIS, with a difference of approximately 0.07 W/m2. Based on these findings, we generate a new TSI dataset (JTSIM-DARA product) at a 6-hour sampling interval. Finally, we have incorporated this new dataset into the TSI composite time series released by the PMOD/WRC. The results indicate that the inclusion of DARA-recorded observations does not alter the consistency, reliability, and stability of the time series.

How to cite: Montillet, J.-P., Finsterle, W., Haberreiter, M., Pfiffner, D., Zhu, P., Wu, D., Koller, S., Ye, X., Yang, D., Fang, W., Qi, J., and Zhang, P.: The JSTIM-DARA  product derived from the TSI Observations Recorded by the FY3E/JTSIM/DARA Radiometer, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5966, https://doi.org/10.5194/egusphere-egu24-5966, 2024.

The accurate determination of sea surface height begins with the precise characterization of the orbit of altimetric satellites with respect to the Earth’s center of mass. To produce precise estimates of the orbital height of such altimetric satellites, Precision Orbit Determination (POD) combines satellite-tracking information with force models, including gravity, atmospheric drag, radiation, and others, which govern the motion of these satellites.
However, it’s important to note that uncertainties arising from the modeling of non-gravitational forces, stemming from the interaction between photons, molecules, atoms, and satellite surfaces, constitute a significant source of error.


With the goal of achieving radial orbit errors below 0.1 mm/year at regional and decadal time scales, an update in the modeling of non-gravitational forces, specifically addressing Earth radiation pressure, was performed. Indeed, the traditional model used in CNES' ZOOM orbit determination software was based on an average approach (Knocke et al., 1988) accounting for latitude and time dependent reflected/emitted radiations which did not consider the spatial and temporal complexity of reflection phenomena, such as cloud dynamics.


To address this issue, an approach involving the use of observations from Earth radiation fluxes, such as CERES (NASA) and ERA5 (ECMWF), was adopted and tested during the lifetime of the Sentinel-6A and CryoSat-2 satellites. These efforts led to substantial improvements in the dynamic modeling of satellite orbits. Comparisons were made between the resulting satellite orbits and those based on the legacy model, with the aim of assessing their impact on sea level measurements. Although a slight discrepancy was observed between the two derived orbits, this difference was attributed to the introduction of empirical forces, typically employed to correct dynamic modeling errors. Consequently, an analysis of these empirical forces confirmed their relevance and underscored the value of the new force model

How to cite: Nocet-Binois, M.: Enhancing satellite orbit accuracy for sea level monitoring through Earth radiation pressure modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6134, https://doi.org/10.5194/egusphere-egu24-6134, 2024.

EGU24-10172 | ECS | Orals | ST4.7

Lunar Imaging Earthshine Telescope, juLIET, for Earth Albedo Measurements  

Katcha Winther, Peter Thejll, and René Fléron

The average global temperature of Earth is governed by the energy balance equation, comparing energy entering and leaving the Earth system. A key parameter in this balance is the Earth’s albedo, determining the ratio of the Sun’s energy being reflected from or absorbed by Earth. The global albedo varies on several different timescales – daily due to changes in cloud cover, seasonally due to changes in foliage and snowfall, and on greater timescales a change in albedo is a reflection of our changing climate. To measure these changes, multi-decadal data is needed.

Data of top-of-the-atmosphere shortwave radiation used in albedo estimation, are primarily gathered by LEO satellites using absolute measurement techniques. These are however affected by the harsh space environment, especially radiation, which causes drift errors in the data, requiring in-flight calibration. The purpose of NASA’s and ESA’s upcoming missions CLARREO and TRUHTS respectively, is to provide state of the art calibration data to account for these errors. However, they do not remove the issue all together.

As an alternative to these absolute measurements, the space based earthshine telescope juLIET (ju Lunar Imaging Earthshine Telescope) aims to estimate the albedo through relative measurements. The Earthshine albedo technique is based on comparing the intensity of Moonlight coming from the visible dayside of the Moon and the Earthshine reflected off the visible nightside of the Moon. As a relative measurement, it is more resilient to calibration drift.

Albedo measurements using the Earthshine technique have been successfully carried out from Earth, but due to Moonlight being several magnitudes brighter than Earthshine, atmospheric scattering of Moonlight reduces the possible precision on the Earthshine intensity. While the issue of atmospheric scattering is removed by going into orbit, measuring the dim Earthshine with a sufficiently high precision to be used for albedo estimation, using the same sensor that measures the Moonlight, still poses a significant challenge, due to scattering and diffraction of Moonlight within the telescope.

To determine the feasibility of the juLIET instrument, an analysis of the optical noise of the telescope is conducted. This analysis is carried out using Zemax OpticStudio and MATLAB, where main contributors to the uncertainty of the measurement are isolated and quantified.

The results of this noise analysis will be extended to determine which lunar phases juLIET can provide measurements of the Earth albedo, during its mission time as primary payload on the small-sat ROMEO developed by IRS, University of Stuttgart. 

How to cite: Winther, K., Thejll, P., and Fléron, R.: Lunar Imaging Earthshine Telescope, juLIET, for Earth Albedo Measurements , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10172, https://doi.org/10.5194/egusphere-egu24-10172, 2024.

EGU24-10791 | ECS | Posters virtual | ST4.7

A Novel Empirical EUV Model with Uncertainty Quantification 

Daniel Brandt and Aaron Ridley

The ubiquitous usage of solar proxies in the nowcasting and forecasting of ionospheric and thermospheric conditions has seen the application of a multitude of techniques to ensure high fidelity representation of the effects of solar EUV forcing on the atmospheric state. The inherent limitations of reliance on a single solar proxy have encouraged the development of numerous EUV irradiance models in which the EUV irradiance in multiple bands is reconstructed from F10.7 solar flux. These models have progressed from lower to higher resolution, as well as higher-fidelity parameterization of time-varying components of the EUV irradiance. We contribute to this development in presenting NEUVAC, a simple, but novel empirical solar EUV model trained on FISM2 data. NEUVAC models the solar EUV irradiance from F10.7 and 81-day averaged F10.7 in 59 wavelength bands between 1 and 1750 Angstroms using a nonlinear parameterization, and performs uncertainty quantification in each band with the assistance of exclusively data-driven methods that exploit the dynamical properties of EUV, and intercorrelations between irradiance in each band. The irradiances provided by NEUVAC highlight the success of the FISM2 program, are suitable for direct ingestion into global ionosphere-thermosphere models, and are structured so that ensembles of irradiance estimates can be generated for principled forecasting and statistical assessment of downstream parameters generated by ionosphere-thermosphere models.

How to cite: Brandt, D. and Ridley, A.: A Novel Empirical EUV Model with Uncertainty Quantification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10791, https://doi.org/10.5194/egusphere-egu24-10791, 2024.

EGU24-11445 | Orals | ST4.7

A change in solar radio spectrum during the decay of the Modern Maximum 

Kalevi Mursula, Alexei Pevtsov, Timo Asikainen, Ismo Tähtinen, and Anthony Yeates

The Sun experienced a period of unprecedented activity during solar cycle 19 in 1950s and 1960s, now called the Modern Maximum (MM). The decay of the MM has changed the Sun, the heliosphere and the planetary environments in many ways. However, this decay may not have proceeded synchronously in all solar parameters. One of the related key issues is if the relation between the two long parameters of solar activity, sunspot number and the solar 10.7cm radio flux, has remained the same during this decay. While a number of studies agree that this relation has indeed changed, no consensus on its validity exists. A recent study argues that there is an inhomogeneity in the 10.7cm radio flux in 1980, which led to a step-like jump ("1980 jump") in this relation. If true, this would imply that the 10.7cm radio flux is ineligible for long-term studies, which would seriously impede versatile studies of the Sun during the MM.

Here we use the 10.7cm radio flux and four other, independent radio flux measurements, the sunspot number, the MgII index and the number of solar active regions in order to study their mutual relations during the decay of MM. We find that all the five radio fluxes depict an increasing trend with respect to the sunspot number from 1970s to 2010s. This excludes the interpretation of the "1980 jump" as an inhomogeneity in the 10.7cm flux, and re-establishes the 10.7cm flux as a reliable and homogeneous long-term measure of solar activity.

We find that the fluxes of longer radio waves increased with respect to the shorter waves, which implies a long-term change in the solar spectrum at radio frequencies. We also find that both the MgII index and the number of active regions increased with respect to the sunspot number, indicating a difference in the long-term evolution in chromospheric and photospheric parameters.

Our results give evidence for important structural changes in solar magnetic fields and solar atmosphere during the decay of the MM when solar activity weakened considerably. These changes have not been reliably documented so far. We also emphasise that the changing relation between the different (e.g. photospheric and chromospheric) parameters should be taken into account when using sunspot number or any single parameter in long-term studies of solar activity.

How to cite: Mursula, K., Pevtsov, A., Asikainen, T., Tähtinen, I., and Yeates, A.: A change in solar radio spectrum during the decay of the Modern Maximum, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11445, https://doi.org/10.5194/egusphere-egu24-11445, 2024.

EGU24-11721 | Orals | ST4.7

Radiation budget at the Baltic Sea surface in 2010 – 2023 from SatBałtyk System 

Tomasz Zapadka, Mirosława Ostrowska, Damian Stoltmann, and Marcin Paszkuta

Global climate change, which causes, among other things, an accumulation of energy in the oceans, may cause irreversible changes to their ecosystems. This can be particularly quickly apparent in bodies of water that are shallow and small in relation to the Oceans, such as the Baltic Sea. In the SatBałtyk System (http://www.satbaltyk.pl), which aims to observe the state of the Baltic Sea environment based on satellite data, maps of the distributions of values of a number of physical biological and chemical parameters of the sea are collected and made available. Within the framework of this System, the SBRB (SatBałtyk Radiation Budget) model was launched, determining data on radiation budget (NET) at the sea surface. Daily maps of the spatial distribution of the radiation budget  and its components at the Baltic Sea surface are created based on data from SEVIRI, AVHRR, MODIS, SBUV/2, TOVS radiometers, and forecast auxiliary models. The component algorithms of this model were developed and validated against empirical data measured directly in the Baltic Sea (Zapadka et al. 2020). The uncertainties in the estimation of the radiation budget for the monthly averages are: RMSD 4 Wm-2 and BIAS -0.5 Wm-2. The individual downward and upward shortwave radiation fluxes are determined with an accuracy of RMSD 3 Wm-2, 1 Wm-2, BIAS 3 Wm-2, 0.1 Wm-2 respectively, and downward and upward longwave radiation fluxes are RMSD 4.5 Wm-2, 3.7 Wm-2, BIAS -0.8 Wm-2, 2.6 Wm-2 respectively. The uniform methodology used since 2010 has enabled an analysis of the variability of the radiation budget and its components at the surface of the Baltic Sea covering 14 years. Despite the natural variation in NET values and its components year-on-year, the analyses showed an annual growth trend of c. 0.7 Wm-2. Interestingly, the increasing trend applies to all NET components. An analysis of the possible causes of the trend observed in recent years may confirm the role of the anthropological factor in these changes.

How to cite: Zapadka, T., Ostrowska, M., Stoltmann, D., and Paszkuta, M.: Radiation budget at the Baltic Sea surface in 2010 – 2023 from SatBałtyk System, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11721, https://doi.org/10.5194/egusphere-egu24-11721, 2024.

EGU24-12284 | Posters on site | ST4.7

Towards Determining the Earth Energy Imbalance from Space - Outcome of a recent ISSI International Team 

Margit Haberreiter, Julien Amand, Edward Baudrez, Wolfgang Finsterle, Nigel Fox, Dave Harber, Norman Loeb, Mustapha Meftah, Jean-Philippe Montillet, Stijn Nevens, Peter Pilewskie, Bill Swartz, Martin Wild, Duo Wu, Xin Ye, and Ping Zhu

A positive Earth Energy Imbalance (EEI) is the energy, which is continuously stored by the Earth and will ultimately released to the atmosphere, causing global warming. The "imperative to monitor Earth’s energy imbalance” (von Schuckmann et al., 2016) has been continuously reported by the Earth’s climate community. The EEI has been identified to be around 0.5 to 1.0 Wm−2. To determine its exact value both the Total Solar Irradiance (TSI) and the Top of the Atmosphere (ToA) Outgoing Radiation (TOR) need to be measured with unprecedented accuracy and precision.However, so far, the EEI could not be determined as the measurements were not sufficiently accurate. This calls for improved instrument technologies as well as a traceable calibration chain of the space instrumentation. To pave the way in that direction, the ISSI International Team "Towards Determining the Earth Energy Imbalance from Space" has been established. We collect the current knowledge of ERB measurements and identify missing elements for measuring EEI from space. Specifically, we collect past and ongoing measurements of the ERB components obtained with instruments such as CLARA, RAVAN, SIMBA, GERB, and CERES. The goal is to evaluate the performance and uncertainty of each of the instruments to identify observational challenges that need to be overcome to be able to measure both TSI and the Earth’s outgoing radiation with the required accuracy to ultimately be able to determine the absolute level of EEI from space.

How to cite: Haberreiter, M., Amand, J., Baudrez, E., Finsterle, W., Fox, N., Harber, D., Loeb, N., Meftah, M., Montillet, J.-P., Nevens, S., Pilewskie, P., Swartz, B., Wild, M., Wu, D., Ye, X., and Zhu, P.: Towards Determining the Earth Energy Imbalance from Space - Outcome of a recent ISSI International Team, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12284, https://doi.org/10.5194/egusphere-egu24-12284, 2024.

EGU24-13691 | Orals | ST4.7

AI to Enhance the Capabilities of EUV-observing Satellites and Estimate Spectral Irradiance 

Benoit Tremblay, Robert Jarolim, Anna Jungbluth, Andrés Munoz-Jaramillo, Kyriaki-Margarita Bintsi, Miraflor Santos, James P. Mason, Angelos Vourlidas, and Sairam Sundaresan

Multiple satellites capture images of the Sun in Extreme Ultraviolet (EUV) light. However, only the Solar Dynamics Observatory (SDO) was equipped with instruments that measure the Sun's EUV spectral irradiance (i.e., MEGS-A and MEGS-B onboard the Extreme Ultraviolet Variability Experiment (EVE) suite). The MEGS-A instrument malfunctioned in 2014, making it impossible to measure the full irradiance spectrum ever since. 

 

Using AI, we explore the translation of a set of EUV images of the Sun into spectral irradiance, effectively replacing the malfunctioning MEGS-A instrument onboard SDO. In other words, we generate a virtual irradiance instrument, MEGS-AI, for SDO. Using an Image-to-Image translation tool (ITI), this virtual instrument can also be trained and added on other EUV-observing satellites like STEREO, GOES, SolO, and the upcoming VIGIL satellite, enabling unprecedented irradiance estimates from additional satellite missions. In the case of the STEREO twin-satellites and VIGIL, this enables estimates of spectral irradiance prior to the Sun rotating into Earth’s view, which directly enables the forecast of enhanced irradiance. Additionally, we explore different combinations of images in different EUV channels and evaluate their contributions in estimating different irradiance channels. Finally, when combined with a neural radiance field model of the Sun (SuNeRFs), MEGS-AI can estimate spectral irradiance from any viewpoint in the solar system, enabling for the first time a complete 4pi spectral irradiance map of the Sun. This can be directly used to estimate the Sun’s impact on other planets in the solar system and to determine the total solar irradiance output in multiple EUV spectral bands.

How to cite: Tremblay, B., Jarolim, R., Jungbluth, A., Munoz-Jaramillo, A., Bintsi, K.-M., Santos, M., Mason, J. P., Vourlidas, A., and Sundaresan, S.: AI to Enhance the Capabilities of EUV-observing Satellites and Estimate Spectral Irradiance, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13691, https://doi.org/10.5194/egusphere-egu24-13691, 2024.

One of the instruments on the Geostationary Operational Environmental Satellites is the Extreme and Ultraviolet Sensor (EUVS).  Channel C of EUVS measures the Magnesium II core-to-wing ratio with high signal-to-noise ratio at a cadence of three seconds.  This presentation will describe the design of the instrument and give an overview of the data collected so far.  Available data products range from the full-cadence operational data measured every three seconds to science-quality daily averages. 

 

The instrument measures the spectrum of the Sun from 275 to 285 nm with a spectral resolution of 0.1 nm.  It uses a diode array with a sampling width of 0.02 nm, providing five samples per slit width. 

 

The first of these instruments became operational in January 2017 and continues through the present.

How to cite: Snow, M. and McClintock, W.: High Precision, High Time Cadence Measurements of the Mg II Index of Solar Activity by the Extreme Ultraviolet Sensor aboard the NOAA GOES-R Series, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15007, https://doi.org/10.5194/egusphere-egu24-15007, 2024.

EGU24-15999 | ECS | Orals | ST4.7

Sampling the diurnal and annual cycles of Earth’s energy imbalance with constellations of satellite-borne radiometers 

Thomas Hocking, Thorsten Mauritsen, and Linda Megner

The Earth’s energy imbalance (EEI), i.e. the difference between incoming solar radiation and outgoing reflected and emitted radiation, is the one quantity that ultimately controls the evolution of our climate system. Despite its importance, the exact magnitude of the energy imbalance is not well known, and because it is a small net difference of about 1 Wm−2 between two large fluxes (approximately 340 Wm−2), it is difficult to measure directly. There has recently been a renewed interest in applying wide-field-of-view radiometers onboard satellites to measure the outgoing radiation, and hence deduce the global annual mean energy imbalance.

Here we investigate how to sample with a limited number of satellite orbits, in order to correctly determine the global annual mean imbalance. Using observational and model data, we have investigated the importance of the local and global diurnal cycles, as they are observed by a satellite, in the determination of the EEI. We simulate satellites in polar (90° inclination), sun-synchronous (98°) and precessing orbits (73°, 82°), as well as constellations of these types of satellite orbits. We present the results of ongoing work concerning different orbits, and how they affect the estimated global annual mean EEI.

How to cite: Hocking, T., Mauritsen, T., and Megner, L.: Sampling the diurnal and annual cycles of Earth’s energy imbalance with constellations of satellite-borne radiometers, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15999, https://doi.org/10.5194/egusphere-egu24-15999, 2024.

EGU24-16132 | Orals | ST4.7

Estimate of the global and regional Ocean Heat Content changes from space gravimetry and altimetry observations to assess the Earth Energy Imbalance variations and trend 

Robin Fraudeau, Florence Marti, Benoit Meyssignac, Alejandro Blazquez, Sebastien Fourest, Michael Ablain, Victor Rousseau, Gilles Larnicol, Marco Restano, Jérôme Benveniste, Roberto Sabia, and Gérald Dibarboure

The Earth energy imbalance (EEI) at the top of the atmosphere (TOA) is the cause of the energy accumulation in the climate system. Measuring the EEI is challenging because it is a globally integrated variable whose variations are small (0.5-1 W.m−2) compared to the amount of energy entering and leaving the climate system (~ 340 W.m-2). 91% of the excess of energy stored by the planet in response to the EEI is accumulated in the ocean in the form of heat making the ocean heat content (OHC) change an accurate proxy of EEI.

In this work, we adopt the space geodetic approach which relies on the sea level budget equation to estimate the OHC changes. The thermosteric sea level change is derived at regional scale from a combination of space altimetry and space gravimetry observations, and divided by the integrated expansion efficiency of heat  to estimate the OHC changes. The global OHC (GOHC) change is then estimated by a spatial integration of the regional OHC changes. The uncertainty in GOHC is estimated by propagation of the uncertainty of input data using the input data error variance-covariance matrix to account for the instrumental and post-processing errors and for the time correlation in errors.

Regional estimates of the OHC changes are validated over the Atlantic Ocean directly against data from in-situ Argo profiles and indirectly by an energy budget approach. In the energy budget approach, surface heat flux derived from ERA5 and CERES TOA radiation budget are combined with regional OHC changes to estimate the north Atlantic meridional heat transport which is then validated against in-situ RAPID and OSNAP estimates. Both validations show good agreement in terms of signal amplitudes and variability with time correlations above 0.6. 

 

Over the period 1993-2022, the GOHC shows a significant positive trend of 0.75 W m-2 [0.61, 1.04] at the 90% confidence level, indicating a positive mean ocean heat uptake or EEI. Comparisons with GOHC estimates based on in-situ ocean temperature measurements over the full ocean depth show good agreement over 2005-2019 (Marti et al. 2023, in review). Over 2000-2020, the ocean heat uptake presents a positive trend of 0.33 W/m²/decade, significant at the 90% confidence level and in agreement with CERES estimate. This EEI trend  reflects an acceleration in ocean warming.

 

The two space geodetic products based on space altimetry and space gravimetry are freely available on the AVISO website. One estimating the GOHC and EEI (https://doi.org/10.24400/527896/a01-2020.003), the other estimating regional OHC over the Atlantic Ocean (https://doi.org/10.24400/527896/a01-2022.012).

How to cite: Fraudeau, R., Marti, F., Meyssignac, B., Blazquez, A., Fourest, S., Ablain, M., Rousseau, V., Larnicol, G., Restano, M., Benveniste, J., Sabia, R., and Dibarboure, G.: Estimate of the global and regional Ocean Heat Content changes from space gravimetry and altimetry observations to assess the Earth Energy Imbalance variations and trend, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16132, https://doi.org/10.5194/egusphere-egu24-16132, 2024.

The Earth energy imbalance (EEI) is a fundamental climate variable that characterizes the energy state of the climate system. When integrated over multiple years, EEI estimates provide the net energy gain (or loss) by the climate system. In addition, measuring accurately the EEI along with surface temperature and atmospheric composition is essential to separate the role of different radiative forcing from the role of feedbacks on the global energy budget enabling further to constraint effective and equilibrium climate sensitivities. In this presentation I review the current EEI observing system performance and uncertainty. I intercompare the different EEI datasets, originating from in-situ and space-based observing systems to evaluate their differences and to assess their uncertainty.

Since 2000 the Clouds and the Earth’s Radiant Energy System (CERES) project provides satellite-based observations of the Earth radiation budget and the EEI with the highest precision (±0.3W.m-2 -1s- on a monthly basis). Nevertheless, because of limitation in the absolute calibration of CERES radiometers the CERES final product needs a bias correction (of about ±2.5W.m-2 -1s-) on the EEI mean. The current best approach to estimating the mean EEI is to estimate the ocean heat uptake (OHU)  which represent 89% of the energy storage  due to the EEI.  Today, the OHU can be derived with the highest accuracy (±0.18W.m-2 -1s- on the mean OHU), from in situ ocean temperature measured by Argo or from the thermal expansion estimated by the difference between satellite altimetry sea level and ocean mass from GRACE. On 2-yr and longer time scales, OHU and CERES EEI estimates show good agreement in EEI variability. But OHU approaches cannot resolve the EEI variability below 1 yr because the energy gain (or loss) induced by EEI over such small time-scales is of the same order of magnitude as the global exchanges of energy between the atmosphere and the ocean.

The different EEI measurements have enabled since 2005 a robust estimate of the mean EEI of +0.75±0.18W.m-2 that is essentially due to anthropogenic emissions of greenhouse gases (GHG). They have also allowed to detect a significantly positive trend in EEI of 0.4±0.3W.m-2 per decade, leading to a doubling of the EEI during the past 20 years in response to continued increases in GHG emissions combined with decreases in aerosol emissions. In addition, on interannual time scales, they showed that the variability in EEI is mostly sensitive to low cloud variability, with ENSO controlling the ±0.5W.m-2 variability on the 4-7yr time scale.  Today, new scientific challenges related to EEI are emerging like the closure of the energy budget from top of the atmosphere to the bottom of the ocean at monthly to decadal time scales, the estimate of the current effective climate sensitivity, the monitoring of the physical climate system response to GHG mitigation policies and others. These new challenges lead to new requirements on the EEI observing system ranging from sustained continuity to higher precision and accuracy. I discuss briefly the need to refine these requirements and some opportunities to meet them in the future.

How to cite: Meyssignac, B.: Mean, Trend, variability and uncertainty in Earth's Energy Imbalance over the last two decades, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16610, https://doi.org/10.5194/egusphere-egu24-16610, 2024.

TRUTHS (Traceable Radiometry Underpinning Terrestrial- and Helio-Studies) is an operational climate mission, aiming to enhance, up to an order-of-magnitude, our ability to estimate the Earth radiation budget, spectrally resolved to support attribution. Through direct measurements of incoming total and spectrally resolved solar irradiances and Earth reflected radiances, spatially resolved, it establishes ‘benchmarks’ against which change/trends can be detected in as short a time as possible. These fiducial reference data sets can be combined with data from other sensors and also serve as ‘gold standard’ references to anchor and upgrade the performance of other space sensors through in-orbit calibration.

TRUTHS will become a founding member of a new class of satellites called SITSats, SI-Traceable Satellites, with payloads explicitly designed to achieve and evidence an uncertainty, in-orbit, at a level commensurate with the exacting goals of long-time-base climate studies. SITSats also facilitate interoperability and enhanced trust in the data from the Earth observation system as a whole, helping to provide observational evidence-based confidence in actions addressing the climate emergency. 

The unprecedented uncertainty of TRUTHS’ globally sampled hyperspectral data underpins many additional applications:

  • Establishing an interoperable, harmonised Earth Observing system incorporating agency and commercial satellites: large and small
  • Top and Bottom of atmosphere reflectances impacting carbon cycle (e.g. land cover, ocean colour, vegetation, methane etc together with similar applications of other hyper/multi-spectral missions). Low uncertainty also facilitates improvements in retrieval algorithms.
  • Transferring radiometric reference values to existing Cal/Val infrastructure (e.g. RadCalNet, Pseudo-Invariant Calibration sites, In-situ ocean colour reference observations; selected surface reflectance test-sites (fluxnet, …), both nadir and multi-angular) and Moon observations.

The mission comprises an “agile” satellite capable to point and image the Earth, Moon and Sun from a 90°polar orbit by the Hyperspectral Imaging Spectrometer (HIS). The HIS provides spectrally continuous observations from 320 to 2400 nm, with a spectral sampling between 2 and 6 nm and a spatial sampling of 50 m. The payload utilises a novel SI-traceable on-board calibration system (OBCS), comprising of the Cryogenic Solar Absolute Radiometer (CSAR), able to realise SI-traceability in space and also measure incoming solar radiation. Together with other optical elements the OBCS links the HIS observations to the CSAR with a target expanded uncertainty 0.3% (k=2).

TRUTHS is implemented by the European Space Agency (ESA) as a UK-led Earth Watch mission in collaboration with Switzerland, Czech Republic, Greece, Romania and Spain. The mission was conceived by the UK national metrology institute, NPL, in response to challenges highlighted by the worlds space agencies, through bodies such as CEOS addressing observational needs of GCOS. The mission is under development by an industrial consortium led by Airbus Defence and Space UK, with a target launch date of 2030 and minimal operations life-time of 5 years with a goal of 8 yrs.

Together with FORUM (ESA) and IASI-NG (CNES/EUMETSAT) it will provide spectrally resolved Earth radiance information from the UV to the Far-Infrared in the coming decade, and in partnership with CLARREO-Pathfinder (NASA) and CSRB (CMA) inaugurate a future constellation of SITSats.

How to cite: Fox, N., Fehr, T., Marini, A., August, T., and Remedios, J.: Traceable Radiometry Underpinning Terrestrial- and Helio- Studies (TRUTHS) – A ‘gold standard’ imaging spectrometer in space for radiation imbalance and in support of the climate emergency , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18864, https://doi.org/10.5194/egusphere-egu24-18864, 2024.

EGU24-20938 | Posters on site | ST4.7

GHOTI: Using the GOES-R EXIS/SPS detectors to create a low-latency, high-cadence, TSI proxy and spectral models 

Steven Penton, Martin Snow, Stéphane Béland, Don Woodraska, and Odele Coddington

The GOES-R series of geostationary satellites include a redesigned instrument for solar spectral irradiance: 
the Extreme ultra-violet and X-ray Irradiance Sensor (EXIS). Our team will be using the Sun Position Sensor (a set of high-cadence broadband visible light diodes) on GOES-16 and GOES-18 EXIS instruments to construct a high-cadence proxy for Total Solar Irradiance (TSI). This has two advantages over the existing TSI measurements: 
1) the measurements are taken at 4 Hz, so the cadence of our TSI proxy is much faster than existing measurements, such as the 6 to 24-hour measurements produced by SORCE or TSIS-1, and 
2) from a geostationary position, the time series of measurements is virtually uninterrupted.

Our calibration of the GOES-R EXIS diode measurements includes thermal and sun-satellite distance corrections, 
while the irradiance calibration relies on TSIS-1 TIM TSI composites. Another measurement from GOES-EXIS that will be used is the Magnesium II core-to-wing ratio. The MgII index is a proxy for chromospheric activity and is measured by EXIS every 3 seconds. The combination of the two proxies is used to generate a model of the full solar spectrum similar to the NRLSSI2 empirical model.

We are in the final year of a four-year grant to develop the TSI proxy and the SSI model.

How to cite: Penton, S., Snow, M., Béland, S., Woodraska, D., and Coddington, O.: GHOTI: Using the GOES-R EXIS/SPS detectors to create a low-latency, high-cadence, TSI proxy and spectral models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20938, https://doi.org/10.5194/egusphere-egu24-20938, 2024.

EGU24-4009 | Posters on site | ST4.9

A new approach to modeling the time-space variations of ionospheric electric currents and magnetic fields during the September 2017 geomagnetic storm 

Martin Fillion, Patrick Alken, Gary Egbert, Astrid Maute, Gang Lu, and Kevin Pham

The study and modeling of Earth’s ionospheric electric currents and of the associated magnetic fields is fundamental for geomagnetic field modeling, and for the study of ionosphere coupling with the neutral atmosphere and the magnetosphere. Ionospheric electric currents, which exist during both quiet and disturbed geomagnetic activity periods, can be studied using magnetic field measurements from ground magnetic observatories and satellites. Modeling these currents during geomagnetic storms is particularly challenging due to the limited data available combined with high time-space variations during such events. In this study, we propose a new approach to modeling the storm-time ionospheric electric currents and magnetic fields. The approach relies on a joint utilization of magnetic data and the physics-based Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM). The TIEGCM time-space variations are first analyzed using a toroidal-poloidal decomposition of the magnetic field. To extract a priori information on the 3D spatial structure of the ionospheric magnetic field, principal component analysis is next applied to the spherical harmonics coefficients to obtain a small number of spatial modes that represent a substantial amount of magnetic field spatial variations. Temporal variations are represented by temporal modes computed with ground observatory data following Egbert et al. (2021). The entire procedure can be carried out in the frequency domain to account for induced fields. Spatial and temporal modes can be combined to parametrized the magnetic field measured by the Swarm satellites and the model coefficients estimated by solving an inverse problem. We present preliminary results obtained with this approach for the geomagnetic storm of September 2017.

How to cite: Fillion, M., Alken, P., Egbert, G., Maute, A., Lu, G., and Pham, K.: A new approach to modeling the time-space variations of ionospheric electric currents and magnetic fields during the September 2017 geomagnetic storm, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4009, https://doi.org/10.5194/egusphere-egu24-4009, 2024.

EGU24-4783 | Orals | ST4.9 | Highlight

Remote-Sensing Magnetotail Dynamics from Low Earth Orbit with CINEMA 

Robyn Millan and Sasha Ukhorskiy and the CINEMA Science Team

Low-altitude measurements provide a unique vantage point for studying processes occurring in the magnetosphere, taking advantage of the fact that energetic particles move quickly along magnetic field lines. Low-Earth-orbiting (LEO) polar satellites can sample a vast volume of space as they rapidly traverse magnetic field lines, obtaining a radial snapshot of the entire magnetotail in minutes. CINEMA (Cross-scale INvestigation of Earth's Magnetotail and Aurora) is a NASA Small Explorer mission concept with the overarching goal to understand the role of plasma sheet structure and evolution in Earth’s multiscale magnetospheric convection cycle. How the magnetotail maintains steady convection, and when and how it decides to explosively release stored energy, are major unsolved mysteries of space physics. CINEMA’s nine satellites in LEO polar orbits each carry an on-board imager, particle sensors, and magnetometers, and quickly traverse the low-altitude footprint of the magnetotail, capturing its evolution at different scales. CINEMA obtains information about the structure of the magnetotail remotely through its imprint on particle pitch-angle distributions, providing an unprecedented view of particle isotropy boundaries. Mesoscale aurora and bursty energetic particle precipitation serve as tracers of specific mesoscale and kinetic-scale dynamics. Field-aligned currents (FACs) that connect the magnetotail to the ionosphere are sensed by measuring magnetic field variations at each satellite. Together, these observations reveal the physics underlying multiscale magnetotail convection.

How to cite: Millan, R. and Ukhorskiy, S. and the CINEMA Science Team: Remote-Sensing Magnetotail Dynamics from Low Earth Orbit with CINEMA, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4783, https://doi.org/10.5194/egusphere-egu24-4783, 2024.

EGU24-6388 | Orals | ST4.9 | Highlight

ELMO: ELectron Microburst Observatory mission to study microbursts 

Shri Kanekal

We describe the ELectron Microburst Observatory mission, ELMO  which is proposed as  a
CubeSat constellation mission to fully characterize microburst event spatial extent systematically for the first time both in latitude  and longitude. ELMO comprises 4 CubeSats two per orbit plane in two orbit planes. ELMO will fly in a high inclination LEO at about 500 km in altitude. The CubeSats will systematically separate both in latitude and longitude over the mission lifetime and will carry MERIT, Miniaturized Electron and Proton Telescope as the the payload. MERIT has been built,tested and delivered  to fly on NASA's HERMES, Lunar Gateway mission. MERIT is a solid state detector particle telescope with two identical sensor heads pointed zenith- and nadir-wards enabling measurement of both downgpoing and upwelling electrons thereby accurately estimating  electron precipitation into the atmosphere.  MERIT  will measure electron and protons over a wide energy range in multiple differential channels with a very time resolution of less than 4 ms.    

ELMO will quantify for the first time the contribution of microbursts to radiation belt electron loss using systematic coordinated multipoint measurements. Energetic electron precipitation affects atmospheric chemistry and therefore climate change. ELMO measures
microbursts with unprecedented time and energy resolution. ELMO provides critical knowledge of electron loss processes required for quantitative prediction of global electron fluxes.

How to cite: Kanekal, S.: ELMO: ELectron Microburst Observatory mission to study microbursts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6388, https://doi.org/10.5194/egusphere-egu24-6388, 2024.

EGU24-6566 | ECS | Posters on site | ST4.9

Ionospheric Conductance Derived from Satellite Measurments: Limitations and Implications 

Pouya Pourkarim and David Knudsen
Ionospheric Pedersen conductance ∑P can be remotely measured using electric and perturbation magnetic fields measured above the high – latitude ionosphere, subject to assumptions of sheet – like current systems, quasi – static electric and magnetic fields, neglect of magnetic perturbations generated by Hall currents, and locally constant ∑P (Sugiura et al., 1982). Using Swarm measurements, we see large variability and lower – than expected magnitudes at small scales, and dawn – dusk asymmetries in large scales of ∑P upon comparison with existing models and results. To rectify the observed discrepancies, we revisit the underlying assumptions, provide root – cause analysis, and discuss the implications.

How to cite: Pourkarim, P. and Knudsen, D.: Ionospheric Conductance Derived from Satellite Measurments: Limitations and Implications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6566, https://doi.org/10.5194/egusphere-egu24-6566, 2024.

The Swarm-E/Enhanced Polar Outflow Probe (e-POP) is in an elliptic (non-circular) and non-Sun-synchronous polar orbit (81° inclination, 325 km perigee × 1500 km initial apogee). This gives the satellite a unique vantage point among LEO satellites for observing plasma and related space weather processes in the topside ionosphere and thermosphere, especially the altitude variations of specific physical phenomena. The imaging and rapid-scanning ion mass spectrometer (IRM) on Swarm E combines the technique of ion time-of-flight (TOF), hemispherical electrostatic analysis, and 2D positional ion detection (imaging) to resolve the mass-per-charge (M/q), energy-per-charge (E/q), and incident direction of each detected ion, and to simultaneously measure the incident plasma current at high (1-ms) cadence. Data acquired over the 8-year period from launch (September 2013) to December 2021 has enabled the quantitative investigation of several important magnetosphere-ionosphere-thermosphere (MIT) coupling processes and the altitude distributions and variations of the resulting plasma composition, structure, and dynamics in the F-region and topside ionosphere-thermosphere. These include the effects of atmospheric photoelectrons on spacecraft charging, molecular and nitrogen (N+) ion enhancements in the active-time auroral ionosphere, and decameter-scale structures in equatorial plasma bubbles, for example. We present an overview of investigations of the long- (solar-cycle time scale) and short-term (down to substorm time scale) variations of the various observed features and associated phenomena in the context of their impact on MIT coupling.

How to cite: Yau, A., Foss, V., Howarth, A., Kastyak-Ibrahim, M., and White, A.: Investigation of Plasma Composition and Small-Scale Density Irregularities on a Non-circular and Non-Sun-Synchronous Polar Low-Earth-Orbit (LEO) Satellite: Swarm-E e-POP Observations in the F-region and Topside Ionosphere-Thermosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6986, https://doi.org/10.5194/egusphere-egu24-6986, 2024.

EGU24-8092 | ECS | Posters on site | ST4.9

A model to estimate the L-band amplitude scintillation index from Swarm: the outer scale length assumption 

Rayan Imam, Yuhao Zheng, Luca Spogli, Lucilla Alfonsi, Claudio Cesaroni, Chao Xiong, Yaqi Jin, Lasse B. N. Clausen, Alan Wood, and Wojciech J. Miloch

Irregularities in the plasma density in the ionosphere affect trans-ionospheric radio signals, resulting in fluctuations in the amplitude and phase of these signals, known as amplitude and phase scintillations. We recently developed a model that relies on ESA’s Swarm constellation to estimate the amplitude scintillation index (S4), representing the plasma density irregularities affecting the L-band Global Navigation Satellite Systems (GNSS) signals. One of the main challenges for this model is the need for estimates/measurements of the outer scale length which, for operational considerations, must be available to the model independent of ground measurements as much as possible. In this paper, we show how this challenge was addressed.

In particular, we rely on the combined measurements from ionosondes, GNSS scintillation monitoring receivers, Swarm 16 Hz faceplate instrument, and Rino’s formula for weak scattering scenario to solve for the outer scale wave number. Then, we develop a climatological map for the outer scale wavenumber to be utilized by the Swarm S4 model.

To achieve this, we rely on conjunctions between Swarm satellites trajectories and GNSS signals paths over locations with co-located ionosondes and ionospheric monitoring GNSS scintillation receivers. We rely on models and assumptions to simplify the equations and to translate the different instruments’ measurements into their equivalent values at the phase screen height (hmF2) assumed by Rino’s formula. We detail the methodology and show the results. The outer scale length has been finally sorted into climatological in magnetic coordinates under different space weather conditions.

How to cite: Imam, R., Zheng, Y., Spogli, L., Alfonsi, L., Cesaroni, C., Xiong, C., Jin, Y., Clausen, L. B. N., Wood, A., and Miloch, W. J.: A model to estimate the L-band amplitude scintillation index from Swarm: the outer scale length assumption, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8092, https://doi.org/10.5194/egusphere-egu24-8092, 2024.

EGU24-9669 | ECS | Posters on site | ST4.9

Harnessing LEO and CubeSat constellations for ionospheric irregularity detection 

Shradha Mohanty and M. Mainul Hoque

Low-earth orbiting (LEO) satellite missions are frequently using the Global Navigation Satellite System (GNSS) Radio Occultation (RO) technique for atmospheric and ionospheric remote sensing. The application of GNSS RO technique has increased manifolds with the advent of CubeSat technology. In this study, we investigated the simultaneous occurrence of local nighttime F-layer ionospheric irregularities and amplitude scintillations in low-latitude equatorial regions using 1 Hz COSMIC-2 electron density profiles (ionPrfs) and high rate 50 Hz ionospheric profiles (conPhs) from Spire’s CubeSat constellation, respectively. Both datasets are accessed from the University Corporation for Atmospheric Research (UCAR) repository.

An ionospheric irregularity detection algorithm is developed using a digital non-recursive finite impulse response (FIR) high-pass filter and applied on both the electron density (Ne) and total electron content (TEC) profiles from COSMIC-2 mission. The filter operates in the s domain, where s is defined as the distance between the highest and lowest tangent point heights. If the fluctuations in Ne and TEC exceed a set threshold, the corresponding COSMIC-2 profile is identified as having irregularities. In case of Spire GNSS-RO profiles, scintillation events are identified when the amplitude scintillation index (S4) at GPS L1 frequency exceeds the set threshold. COSMIC-2 and Spire datasets from September 2021 until May 2023 (20 months) are used in this long-term comparative study.

We observe a good agreement in the statistics of number of Spire and COSMIC-2 profiles detecting (showing possible signature of) scintillations/ ionospheric irregularities. Both Spire and COSMIC-2 data show that the scintillation occurrence rate is much higher during the equinoxes (spring and autumn seasons) agreeing well with existing scintillation literature. From the COSMIC-2 data alone, we also notice a direct relation with the solar activity, i.e., the number of irregularity events slowly increases as we approach the solar maximum. This study indicates the capability of LEO satellites and CubeSat missions, especially in GNSS-RO configuration, for providing an important contribution to scintillation monitoring.

How to cite: Mohanty, S. and Hoque, M. M.: Harnessing LEO and CubeSat constellations for ionospheric irregularity detection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9669, https://doi.org/10.5194/egusphere-egu24-9669, 2024.

EGU24-10946 | Posters on site | ST4.9

The VirES service as a platform for accessing and analysing geomagnetic data 

Ashley Smith, Martin Pačes, and Daniel Santillan and the ESA & Swarm DISC

VirES is an ESA service which was been developed to support the goals of the Swarm mission, providing a number of mechanisms for accessing and working with Swarm products. It has since been extended to cover other LEO datasets under the Swarm umbrella: calibrated platform magnetometer data from Cryosat-2, GRACE, GRACE-FO, GOCE, as well as INTERMAGNET ground observatory data, with plans for more. We provide a graphical web interface (currently only supporting Swarm data) [1], API-based access via both the OGC standards and the HAPI specification [2], a Python client [3], and a Jupyter-powered cloud environment (so-called Virtual Research Environment - VRE) and associated notebook collection [4]. Through these connected approaches, we provide a variety of pathways for interaction with the data and models (see also: the Swarm data handbook [5]).

Swarm activities are shifting to toolboxes and on-demand processing (to interactively deliver higher-level products), more open-source software, and more connection with other datasets and data providers. We provide some of these Python tools preinstalled in the VRE alongside other thematic libraries, and are developing SwarmPAL [6] in collaboration with the Swarm community.

These works contain contributions from EOX IT Services and many people across ESA, Swarm DISC, and the wider community.

[1] https://vires.services
[2] https://vires.services/hapi
[3] https://viresclient.readthedocs.io
[4] https://notebooks.vires.services
[5] https://swarmhandbook.earth.esa.int
[6] https://swarmpal.readthedocs.io

How to cite: Smith, A., Pačes, M., and Santillan, D. and the ESA & Swarm DISC: The VirES service as a platform for accessing and analysing geomagnetic data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10946, https://doi.org/10.5194/egusphere-egu24-10946, 2024.

EGU24-11337 | Orals | ST4.9 | Highlight

The asymmetry towards stronger Birkeland currents in the Northern Hemisphere 

John Coxon, Sarah Vines, Steve Milan, and Brian Anderson

Iridium satellites in low-Earth orbit have transformed our knowledge of geospace by enabling the AMPERE dataset. We employ AMPERE data from October 2009 to December 2021 to examine the interhemispheric asymmetry in Birkeland currents over the span of a solar cycle. We take daily averages of the upward and downward current in both hemispheres and examine the systematic asymmetry by removing the seasonal trend. We find that Birkeland currents are stronger in the Northern Hemisphere than in the South after removing the seasonal trend, consistent with Coxon et al. (2016). We explore how this asymmetry manifests over a solar cycle and compare the variation of the asymmetry to other parameters.

How to cite: Coxon, J., Vines, S., Milan, S., and Anderson, B.: The asymmetry towards stronger Birkeland currents in the Northern Hemisphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11337, https://doi.org/10.5194/egusphere-egu24-11337, 2024.

EGU24-11988 | Orals | ST4.9

Overview of the EZIE (Electrojet Zeeman Imaging Explorer) Mission 

Jeng-Hwa Yee, Jesper Gjerloev, Nelofar Mosavi-Hoyer, Rebecca Wind-Kelly, William Swartz, and Sidharth Misra

EZIE, the Electrojet Zeeman Imaging Explorer, is a NASA three-Cubesat Heliophysics mission scheduled to launch in late 2024 or early 2025. It employs four downward and cross-track looking miniaturized radiometers on each of the 6U CubeSat, flying in a pearls-on-a-string managed formation, to measure, for the first time, the two-dimensional structure and the temporal evolution of the electrojets flowing at altitudes of ~100–130 km. The four identical radiometers simultaneously measure polarimetric radiances of the molecular oxygen thermal emission at 118 GHz and employs the Zeeman sensing technique to obtain the current-induced magnetic field vectors at ~80 km, an altitude region very close to the electrojet.  This measurement technique allows for the remote sensing of the meso-scale structure of the electrojets at four different cross-track locations simultaneously at altitudes notoriously difficult to measure in situ. The compact 118-GHz heterodyne spectropolarimeters leverage technologies demonstrated by NASA’s TEMPEST-D and CubeRRT missions and the CubeSat bus from RAVAN, CAT, TEMPEST-D, and CubeRRT. Differential drag maneuvers are used to manage satellite along-track temporal separation to within 2–10 minutes between adjacent satellite to record the electrojet temporal evolution without the need for on-board propulsion. The combination of the sensing technique, compact instrument and Cubesat technologies allow EZIE to cost-effectively obtain never-before “mesoscale” measurements needed to understand how the solar wind energies stored in the magnetosphere are transferred to the thermosphere and ionosphere.  In this paper, we will present an overview of the EZIE mission, its science objectives, the Zeeman sensing technique employed, and the measurement products to be provided.

How to cite: Yee, J.-H., Gjerloev, J., Mosavi-Hoyer, N., Wind-Kelly, R., Swartz, W., and Misra, S.: Overview of the EZIE (Electrojet Zeeman Imaging Explorer) Mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11988, https://doi.org/10.5194/egusphere-egu24-11988, 2024.

EGU24-12382 | Orals | ST4.9

Ten Years of Low-Earth Orbit Observations from CASSIOPE/Swarm-Echo 

Andrew Howarth, Andrew Yau, Paul Bernhardt, Gordon James, David Knudsen, Richard Langley, and David Miles

From the vantage point of an elliptic, polar, low-earth orbit (81o inclination, 325 km x 1500 km initial apogee/perigee), CASSIOPE/Swarm-Echo has been observing the ionosphere-thermosphere system for over ten years. The Enhanced Polar Outflow Probe (e-POP) payload onboard collects data on space weather and related phenomena, including measurements of the local magnetic field, low-energy ion and electron energy distributions, high-frequency radio waves (natural and man-made), GPS signals, and aurora. These observations from a non-sun-synchronous orbit over a range of altitudes constitutes a unique data set that allows for investigation of the earth’s magnetic field and related current systems, upper atmospheric dynamics, auroral dynamics, and related coupling processes among the magnetosphere, ionosphere, thermosphere, and plasmasphere. This presentation will highlight the discoveries of the ten years of e-POP operation, including recent work on plasma waves generated by moving charged space objects and machine-learning techniques applied to analysis of magnetic field data and auroral images. We will also present some of the new Swarm-Echo data products and system tools available for use and look at the future direction of both the mission and the evolving data set.

How to cite: Howarth, A., Yau, A., Bernhardt, P., James, G., Knudsen, D., Langley, R., and Miles, D.: Ten Years of Low-Earth Orbit Observations from CASSIOPE/Swarm-Echo, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12382, https://doi.org/10.5194/egusphere-egu24-12382, 2024.

EGU24-13334 | Orals | ST4.9

The RADiation Impacts on Climate and Atmospheric Loss Satellite (RADICALS) Mission 

Louis Ozeke, Ian Mann, Christopher Cully, David Milling, Michael Lipsett, Robert Ranking, Kathryn McWilliams, Robyn Fiori, David Cullen, Robert Fedosejevs, Greg Enno, Robert Zee, Martin Conners, William Ward, Leonid Olifer, Robert Marshall, David Barona, Andrew Yau, and Andrew Howarth

The RADiation Impacts on Climate and Atmospheric Loss Satellite (RADICALS) is a low-Earth orbiting Canadian small satellite mission investigating the transport of space radiation into the atmosphere, and its impact on Earth’s climate. Scheduled for launch in late 2026, the mission will launch into a polar orbit with an integrated payload comprising two back-to-back look direction High Energy Particle (HEP) telescopes, an X-Ray Imager (XRI) to remote sense energetic particle precipitation using back-scattered Bremsstrahlung X-rays, and a boom mounted FluxGate Magnetometer (FGM) and Search Coil Magnetometer (SCM). Using an innovative Thomson spin-stabilized configuration, the satellite will sample the pitch angle distributions in the spin-plane twice per spin. The back-to-back HEP look directions allow for a contemporaneous view of the down-going and back-scattered up-going electrons, at the same time as XRI remote-senses the related Bremsstrahlung, and the magnetometers provide in-situ magnetic signatures of a range of plasma waves. The key measurement of the pitch angle resolved energetic electron precipitation (EEP) and related back-scatter, including a resolved loss cone, will allow a detailed assessment of the energetic particle energy input to the atmosphere. Measurements of EEP, in addition to measurements of solar energetic particle (SEP) precipitation, will represent a critical data set for assessing the role of space radiation in the climate system, for example through the catalytic destruction of ozone in the middle atmosphere by NOx and HOx. Accurately quantifying the impacts of this space radiation on climate requires accurate and loss cone-resolved characterization of the flux of these precipitating energetic particles for inclusion into whole atmosphere models. The RADICALS explorer will also enable research into potentially catastrophic space-weather radiation effects on satellite infrastructure, and assess impacts on space weather-related interruptions to high frequency radio communications including in relation to aircraft operations in polar regions. Additional cube- and micro-satellite missions, together with the RADICALS, could form a powerful mini--constellation exploring the space weather-climate system.

How to cite: Ozeke, L., Mann, I., Cully, C., Milling, D., Lipsett, M., Ranking, R., McWilliams, K., Fiori, R., Cullen, D., Fedosejevs, R., Enno, G., Zee, R., Conners, M., Ward, W., Olifer, L., Marshall, R., Barona, D., Yau, A., and Howarth, A.: The RADiation Impacts on Climate and Atmospheric Loss Satellite (RADICALS) Mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13334, https://doi.org/10.5194/egusphere-egu24-13334, 2024.

EGU24-13910 | Posters on site | ST4.9 | Highlight

Grotifer: a Profound Change in the Double-Probe Instrument Design to Provide Highly Accurate Three-Component Electric Field Measurements throughout the Heliosphere 

Solène Lejosne, David Auslander, John Bonnell, Scott Candey, Dave Klumpar, Tatsuyoshi Kurumiya, Neli Montalvo, David Pankow, John Sample, and Van Vu

No instrument is currently capable of consistently measuring all three components of the DC and low frequency electric field (E-field) throughout the heliosphere with sufficient accuracy to determine the smallest, and most geophysically relevant component: the E-field component parallel to the background magnetic field. E-field measurements in the heliosphere are usually made on spinning spacecraft equipped with two disparate types of double probe antennas: (1) long wire booms in the spin plane, and (2) ~10 times shorter rigid booms along the spin axis. On such systems, the potential difference (signal + noise) is divided by the boom length to produce a resultant E-field component. Because the spacecraft-associated errors are larger nearer the spacecraft, the spin plane components of the E-field are well measured while the spin axis component are poorly measured. As a result, uncertainty in the parallel E-field is usually greater than its measured value. The new design proposed by the Grotifer team is a way to overcome this difficulty. It consists of mounting detectors on two rotating plates, oriented at 90 degrees with respect to each other, on a non-rotating central body. Each rotating plate has two component measurements of the E-field such that the Twin Orthogonal Rotating Platforms provide four instantaneous measurements of the E-field, and the three E-field components are well-measured by the rotating detectors. Grotifer marks a profound change in E-field instrument design that represents the best path forward to close the observational gap that currently hampers resolution of significant science questions at the forefront of space plasma physics research. Here, we present recent advances in the development of the Grotifer design and we demonstrate the feasibility of its implementation in a 27-U CubeSat designed for a Low Earth Orbit mission.

How to cite: Lejosne, S., Auslander, D., Bonnell, J., Candey, S., Klumpar, D., Kurumiya, T., Montalvo, N., Pankow, D., Sample, J., and Vu, V.: Grotifer: a Profound Change in the Double-Probe Instrument Design to Provide Highly Accurate Three-Component Electric Field Measurements throughout the Heliosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13910, https://doi.org/10.5194/egusphere-egu24-13910, 2024.

EGU24-14017 | Orals | ST4.9 | Highlight

LEO Satellites as Sensors for Thermospheric Mass Density and Drag Research   

Jeffrey Thayer, Marcin Pilinski, Eric Sutton, Zach Waldron, and Vishal Ray

The charge to the space science community is to improve specification and forecast of the low Earth orbit (LEO) space environment to provide reliable collision avoidance and risk assessment analyses for space traffic management and reduce the number of false conjunction warnings. The challenge is that the prediction of LEO object trajectories is severely limited. This is due primarily to poorly captured variability in neutral density estimates during space weather events, resulting in large and variable position errors of all resident space objects across LEO. To improve operations in LEO, the specification and forecast of the thermosphere neutral mass density must improve.

Most recently launched LEO satellites are equipped with global navigation satellite system (GNSS) devices, making them excellent sources of continuous orbit ephemeris to enable precision orbit determination (POD). Many are also equipped with attitude and vehicle knowledge to allow for the construction of an accurate force model. Combining these “data of opportunity” from LEO satellites with POD processing tools offers the possibility of extracting thermospheric mass density information regularly and globally from the multitude of GNSS-equipped LEO satellites in operation today.

This talk explores this possible trove of LEO space environment data by investigating methods and providing specificity to the level of data information required to provide useful mass density outcomes. The ICESAT-2 spacecraft is used as a test vehicle for this type of analysis. The NASA GSFC GEODYN POD software is employed to produce precise science orbits for the ICESAT-2 spacecraft. These precise science orbits are then used to extract mass density estimates along specified orbital arcs. Simulation is also employed to address the potential errors of system requirements and how they can influence the thermospheric mass density estimate from LEO spacecraft. The future GDC mission will also be highlighted as a much-needed LEO space environment resource for direct multi-point measurements of the thermospheric gas and ionospheric plasma. These direct neutral measurements will enable a careful validation of POD-extracted densities. By fully characterizing all free-stream parameters, GDC is also a well-equipped constellation for studying the gas-surface interactions critical for drag research.

How to cite: Thayer, J., Pilinski, M., Sutton, E., Waldron, Z., and Ray, V.: LEO Satellites as Sensors for Thermospheric Mass Density and Drag Research  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14017, https://doi.org/10.5194/egusphere-egu24-14017, 2024.

EGU24-17736 | ECS | Posters on site | ST4.9

Neural network-based calibration of Swarm Langmuir Probe ion densities 

Artem Smirnov, Yuri Shprits, Hermann Lühr, Alessio Pignalberi, and Chao Xiong

    The European Space Agency's Swarm constellation consists of three spacecraft (A, B, and C). Each of the satellites is equipped with a Langmuir probe (LP), which measures ion densities and temperatures. The LP processing assumes that the plasma consists exclusively of oxygen ions, which leads to the nighttime overestimation of plasma densities due to non-negligible influence of light ions that is not accounted for in the LP processing. Each of the Swarm satellites also provides electron density measurements by the Faceplate (FP), which is part of the Thermal Ion Imager (TII) suite. The FP densities do not depend on assumptions of the plasma composition. In this study, we use the FP densities as a reference, in order to calibrate the LP observations. We model the ratio of FP to LP data using neural networks. We create three models, for each of the satellites, and are able to produce, even from sparse observations, correction factors for Swarm LP densities. The proposed correction exhibits significant variations based on local time, season, altitude, and solar activity, consistent with the presence of light ions due to the downward ambipolar diffusion from plasmasphere. The developed model resolves the nighttime overestimation by Swarm-LP. The corrected LP data are in excellent agreement with COSMIC radio occultation observations, and can be used for numerous applications including empirical modeling of the topside ionosphere.

How to cite: Smirnov, A., Shprits, Y., Lühr, H., Pignalberi, A., and Xiong, C.: Neural network-based calibration of Swarm Langmuir Probe ion densities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17736, https://doi.org/10.5194/egusphere-egu24-17736, 2024.

EGU24-18046 | ECS | Posters virtual | ST4.9

Dynamical Complexity in Swarm-Derived Storm and Substorm Activity Indices Using Information Theory: Further Evidence for Interhemispheric Asymmetry 

Constantinos Papadimitriou, Georgios Balasis, Adamantia Zoe Boutsi, Stelios Potirakis, Ioannis A. Daglis, and Omiros Giannakis

In November 2023, the ESA Swarm constellation mission celebrated 10 years in orbit, offering one of the best-ever surveys of the topside ionosphere. Among other important achievements, it has been recently demonstrated that Swarm data can be used to derive space-based geomagnetic activity indices. These can be used like the standard ground-based geomagnetic indices for monitoring magnetic storm and magnetospheric substorm activity. Given the fact that the official ground-based index for the substorm activity (i.e., the Auroral Electrojet – AE index) is constructed by data from 12 ground stations, solely in the northern hemisphere, it can be said that this index is predominantly northern, while the Swarm-derived AE index may be more representative of a global state, since it is based on measurements from both hemispheres. Recently, many novel concepts originated in time series analysis based on information theory have been developed, partly motivated by specific research questions linked to various domains of geosciences, including space physics. Here, we apply information theory approaches (i.e., Hurst exponent and a variety of entropy measures) to analyze the Swarm-derived magnetic indices around intense magnetic storms. We show the applicability of information theory to study the dynamical complexity of the upper atmosphere, through highlighting the temporal transition from the quiet-time to the storm-time magnetosphere, which may prove significant for space weather studies. Our results suggest that the spaceborne indices have the capacity to capture the same dynamics and behaviors, with regard to their informational content, as the traditionally used ground-based ones. A few studies have addressed the question of whether the auroras are symmetric between the northern and southern hemispheres. Therefore, the possibility to have different Swarm-derived AE indices for the northern and southern hemispheres respectively, may provide, under appropriate time series analysis techniques based on information theoretic approaches, an opportunity to further confirm the recent findings on interhemispheric asymmetry. Here, we also provide evidence for interhemispheric energy asymmetry based on the analyses of Swarm-derived auroral indices AE North and AE South.

How to cite: Papadimitriou, C., Balasis, G., Boutsi, A. Z., Potirakis, S., Daglis, I. A., and Giannakis, O.: Dynamical Complexity in Swarm-Derived Storm and Substorm Activity Indices Using Information Theory: Further Evidence for Interhemispheric Asymmetry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18046, https://doi.org/10.5194/egusphere-egu24-18046, 2024.

EGU24-19763 | Orals | ST4.9

Demonstrating the accessibility of Space with SBUDNIC 

Lorenzo Bigagli and the SBUDNIC Team (2)

SBUDNIC is a student-managed project that demonstrated the potential for efficient, inexpensive, open-source satellite design and production by (1) launching a 3U CubeSat with a reproducible parts cost of 6.210 USD; (2) completing design, development, and testing within 14 months; and (3) doing this in a team of under 30 undergraduate and graduate students with no prior Space systems experience.

SBUDNIC’s low unit cost precluded the use of most Space-qualified components, leading to novel subsystem designs that deviated from industry practices. A particularly important contribution to Space technology was a Kapton drag sail designed to stabilize SBUDNIC and accelerate its deorbiting.

Over SBUDNIC's lifetime, the team used publicly available positioning data (collected by the United States Space Force, and as compiled and shared on space-track.org) to monitor the trajectory of SBUDNIC and the other 3U satellites that launched with it. SBUDNIC's reentry from 550 km was swift, especially in comparison to the 3U reference satellites: it occurred on August 10, 2023, after only 441 days in Space. By comparison, the orbit of the 3U reference satellites decayed around 50 kilometers over that same time span. SBUDNIC's rapid decay therefore suggests that the drag sail was effective and functioned to purpose. SBUDNIC’s deorbit was 95% faster than anticipated by pre-launch engineering simulations, suggesting a far-higher-than-average atmospheric density at its altitude, likely influenced by heightened solar activity, although further investigation might identify additional contributing factors to such accelerated descent.

SBUDNIC's key goal of making Space exploration more accessible is not limited to the availability of the parts used. The entire satellite project follows the Open Architecture philosophy, and significant effort was made to engage student and hobbyist communities with the mission. The timely program execution, launch, and subsequent deorbit of SBUDNIC demonstrated techniques for manufacture and design that can facilitate low-cost, short-timeline satellite programs for many applications. Additionally, SBUDNIC's orbital decay data sets, though unintended, offer scientific value for Space Weather studies, underscoring the potential of LEO satellites in understanding geospace dynamics.

The SBUDNIC project was a collaboration between the National Research Council of Italy and the Brown University School of Engineering, with support from D-Orbit, AMSAT-Italy, La Sapienza-University of Rome and NASA Rhode Island Space Grant.

How to cite: Bigagli, L. and the SBUDNIC Team (2): Demonstrating the accessibility of Space with SBUDNIC, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19763, https://doi.org/10.5194/egusphere-egu24-19763, 2024.

EGU24-20341 | ECS | Orals | ST4.9 | Highlight

Can we intercalibrate satellite measurements by means of data assimilation? An attempt on LEO satellites 

Angelica M. Castillo Tibocha, Yuri Y. Shprits, Nikita A. Aseev, Artem Smirnov, Alexander Drozdov, Sebastian Cervantes Cervantes, Ingo Michaelis, Marina Garcı́a Peñaranda, and Dedong Wang

Understanding the dynamics of energetic electrons in the radiation belts is key to protect space borne equipment and astronauts on-board spacecraft missions. Therefore, global reconstruction of the near-Earth radiation environment should be available at all times, radial distances and geomagnetic latitudes. Low Earth Orbit (LEO) satellites provide a large data set of rapid observations of the radiation belt region over a wide range of magnetic local times (MLT). However, the use of this data set is rather complicated due to possible proton contamination of electron fluxes and the observation of electron precipitation, leading to high variability of electron measurements, considerable instrumental errors and the need for background correction. In this study, we present a new intercalibration method for satellite measurements of energetic electrons in the radiation belt region using a data assimilation approach. Our aim is to intercalibrate the electron flux measurements of the POES satellites NOAA-15,-16,-17,-18,-19 and MetOp-02 against RBSP observations for the period October 2012 to December 2013. For this, we use a reanalysis of the radiation belt region, obtained by assimilating RBSP and GOES electron data into 3-D Versatile Electron Radiation Belt (VERB-3D) code simulations via a standard Kalman filter. Since the reanalysis provides global reconstruction of the state of the system. We compare the POES/MetOp data with our reanlysis and estimate the flux ratios at each time, location and energy. These ratios are averaged over time and space to obtain energy dependent recalibration coefficients. In order to validate our results, we perform a traditional conjunction study between POES/MetOp satellites and the Van Allen probes. Similarly, we estimate flux ratios for all the found conjunctions and calculate the corresponding energy dependent recalibration coefficients. The conjunction coefficients and the DA estimated coefficients show very good agreement. Additionally, the use of data assimilation allows for improved statistics, as the number of possible ratios is considerably improved. The recalibration coefficients estimated using the our data assimilation approach leads to good resemblance and agreement between the recalibrated POES/MetOp data set and the RBSP observations.

How to cite: Castillo Tibocha, A. M., Shprits, Y. Y., Aseev, N. A., Smirnov, A., Drozdov, A., Cervantes, S. C., Michaelis, I., Garcı́a Peñaranda, M., and Wang, D.: Can we intercalibrate satellite measurements by means of data assimilation? An attempt on LEO satellites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20341, https://doi.org/10.5194/egusphere-egu24-20341, 2024.

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