Presentation type:
ST – Solar-Terrestrial Sciences

EGU23-8054 | Orals | ST2.1 | Julius Bartels Medal Lecture

From Geomagnetism and Space Science to Space Weather 

Hermann Opgenoorth

Early studies of “geo-magnetism” dealt with the understanding of long-term developments and short-term disturbances in the geo-magnetic field as measured by magnetometers on ground level. Soon after the IGY the concept of several co-existing and globally or locally interacting ionospheric current systems (DP1 & 2) was born. Both systems seemed to respond differently to solar wind driving conditions and internal magnetospheric processes. Through continued global international study efforts, like e.g. the International Magnetospheric Study (IMS) and later the International Solar Terrestrial Physics program (ISTP) the 2-dimenional monitoring of geomagnetic “disturbances”, now understood as complex signatures of different current systems within and beyond the upper atmosphere, became a powerful tool to monitor and study the complicated three-dimensional coupling of the magnetosphere to the upper atmosphere and its ultimate relation to certain solar wind drivers of magnetospheric conditions.

 

Geomagnetic observations, both globally and regionally, are today a valuable asset to put the very local measurements of magnetospheric satellites (even if “multi-point”) into its proper context with respect to the dynamics of the magnetosphere. The ultimate goal of such measurements today is not only to identify the energy and activity state of the magnetosphere as such, but also to study the exact location, strength and spatio-temporal development of the most powerful short-lived magnetic disturbances that we know, the so-called magnetospheric substorms and the closely related intensifications of major magnetic storms.

 

The study of the physics of the geo-space environment in response to solar activity and solar wind driving has over the last twenty years matured to make first useful predictions of a large variety of plasma processes in near-Earth space, which have the potential to detrimentally affect human space exploration and human technological infrastructure both on ground and in space. The fast-growing research and operational field of Space Weather has stimulated new active research (including advanced model efforts) to get to the bottom of some of the most effective geo-space plasma phenomena, and to understand the variability of ionospheric currents, and their connection to the outer magnetosphere. This is at present one of the most intriguing scientific problems in the field of Space Weather. Potentially any conducting infrastructure on the ground can be detrimentally or catastrophically affected by fast changes in the magnetic field (dB/dt) via geomagnetically induced currents (GICs). In parallel, the involved ionospheric current systems can cause further secondary impacts on space-borne communication and navigations systems via ionospheric plasma instabilities and atmospheric drag effects on satellite orbits.

 

In my presentation I will give a short background to the historical progress of space science with the help of magnetometer data, and then highlight a selection of recent research topics, where global and regional magnetometer networks (together with a multitude of dedicated space missions) represent a very important part of the systematic and coordinated study of the near-Earth plasma environment, the coupled solar wind - magnetosphere - ionosphere – atmosphere “System of Systems”.

How to cite: Opgenoorth, H.: From Geomagnetism and Space Science to Space Weather, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8054, https://doi.org/10.5194/egusphere-egu23-8054, 2023.

EGU23-8687 | ECS | Orals | ST1.6 | ST Division Outstanding Early Career Scientist Award Lecture

On the evolutionary aspects of solar coronal holes 

Stephan G. Heinemann

Coronal holes (CH) are large, long-lived structures commonly observed in the solar corona as regions of reduced emission in EUV and X-ray wavelengths. They feature a characteristic open magnetic field configuration along which ionized electrons and atoms are accelerated into the interplanetary space. The resulting outflowing plasma is called high seed solar wind stream (HSS; see Cranmer 2009 and references therein). These HSSs are the major cause of minor to moderate geomagnetic activity at Earth (see Richardson 2018 and references therein).

To be able to predict the arrival and impact of those disturbances accurately, their origin and evolution need to be studied in detail. And to do so, it is imperative that CHs are accurately and reliably extracted, thus leading to the development of the Collection of Analysis Tools for Coronal Holes (CATCH). By using the intensity gradient across the CH boundary, it is possible to robustly extract CHs whose properties can then be analyzed. We find that the area of long-living CHs generally evolves by growing to a maximum before decaying. However, the associated magnetic field does not evolve equally. Depending on the CH, we find a correlation, an anti-correlation or even no correlation over the course of its lifetime. Therefore, we believe that the evolution of a CHs magnetic field is primarily driven by the large-scale connectivity changes in the Sun's global magnetic field. Further, we find that the plasma properties within CHs show a significant center to boundary gradient, which may justify the distance-to-boundary parameter used in some solar wind modeling.

To study the evolution of CHs in detail, a 360° view of the Sun is necessary; however, the magnetic far-side of the Sun still eludes. The few snapshots with Solar Orbiter provide only a fragmented picture of the magnetic field on the solar far-side. We found that by using EUV observations of the transition region (specifically using Stereo) it is possible to estimate the magnetic field density of CHs on the solar far side. In addition, we are currently investigating the incorporation of helioseismic observations into synoptic magnetograms to generate a maps that show the magnetic field of the whole Sun at a given time.

How to cite: Heinemann, S. G.: On the evolutionary aspects of solar coronal holes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8687, https://doi.org/10.5194/egusphere-egu23-8687, 2023.

ST1 – The Sun and Heliosphere

EGU23-375 | ECS | Orals | ST1.1

Electron acceleration mechanisms at Earth’s quasi-perpendicular bow shock 

Martin Lindberg, Andris Vaivads, Savvas Raptis, and Tomas Karlsson

We use the Magnetospheric Multiscale mission to observe electron acceleration events at Earth’s quasi-perpendicular bow shock. Acceleration mechanisms up to mildly relativistic electron energies are investigated in order to provide more insight into the long-standing injection problem. The events are chosen for their diversity in observed high energy electron flux and shock angle, θBn, enabling the Stochastic Shock Drift Acceleration theory to be further tested for different shock parameters. An alternative acceleration mechanism is also presented. The electron acceleration region of this unusual event is associated with a decrease in wave activity, inconsistent with common electron acceleration mechanisms such as Diffusive Shock Acceleration and Stochastic Shock Drift Acceleration. The energetic electron population is shown to have a bi-directional pitch-angle distribution, indicating parallel heating along the magnetic field lines.
We propose a two-step acceleration process where energetic field-aligned electrons originating from the electron foreshock act as a seed population further accelerated by a shrinking magnetic bottle process. Furthermore, we present evidence for electron pitch-angle scattering at the shocks and discuss its importance and different roles for the different electron acceleration mechanisms mentioned above.

How to cite: Lindberg, M., Vaivads, A., Raptis, S., and Karlsson, T.: Electron acceleration mechanisms at Earth’s quasi-perpendicular bow shock, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-375, https://doi.org/10.5194/egusphere-egu23-375, 2023.

EGU23-1378 | Posters virtual | ST1.1

Relative variation of granulation size as a function of global solar parameters  

Alexey Sharov and Arnold Hanslmeier

Reliable data on the range and distribution of solar granulation size are essential for modeling plasma convection, studying the magnetic activity cycle, and measuring the Sun's global parameters. Most known morphometric studies of solar granulation measure and document mean area or equivalent diameter of granules from high-resolution optical image time series. One of the main shortcomings of these studies is that the mean area or equivalent diameter cannot represent the characteristic scale of granular cells due to the skewed size distribution. The measured mean granular size is particularly susceptible to the influence of outliers due to occasional irregularities in image time series, unsuitable image quality, e.g. local blurring, and errors in automatic image processing. The lack of consolidated analytical formulations linking changes in granulation size to global solar variability complicates verification of empirical results. It is significant that over the last 70 years the observed value of the relative changes in the average size of granular cells associated with the solar magnetic cycle has declined by an order of magnitude from 20% to 2%.

In this study, we introduce the normalized version of the mean granular area, called the mean extent, which is defined as the area of a granular cell divided by the area of the smallest bounding box enclosing the cell, with averaging over all cells in the observation frame. In contrast to other known granulation properties, the proposed dimensionless parameter has a normal distribution, is less scattered and invariant to scaling effects, e.g. because of defocus. We write some basic expressions for the relative variation in granulation extent and determine the magnitudes of the relative changes in the horizontal size of granular cells due to variations in global solar parameters. We define that the total number of granular cells and their mean size decrease while the solar radius, effective temperature, luminosity and granulation time scale increase with increasing sunspot area.

The specific behavior of mean extent versus mean area and contrast of granular cells was tested using Hinode image sequences obtained in the blue continuum channel with a 27- and 1-day cadence over descending and ascending phases of the 24th activity cycle, and compared to corresponding sunspot indices. The consistent 14- and 378-day delays in the cause-and-effect relationship between sunspot number and granulation scale were revealed in the daily and synoptic time series, respectively, and explained by rotational effects. Remarkably, the mean granular extent varies in phase with the sunspot indices; its long-term average was measured at 0.65, which corresponds to the predominantly hexagonal shape of the granular cells. Higher values of granular extent indicate regularization and compaction of the granulation pattern in both quiescent and active regions. We conclude that the mean size and extent of granular cells measured at the center of the disk could become a reliable index of solar convection and a reactive indicator of global magnetic activity, although the mean granulation size in polar regions remains somewhat uncertain, worthy of further study with high-resolution optical data from extra-ecliptic missions.

How to cite: Sharov, A. and Hanslmeier, A.: Relative variation of granulation size as a function of global solar parameters , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1378, https://doi.org/10.5194/egusphere-egu23-1378, 2023.

EGU23-1395 | ECS | Posters on site | ST1.1

Deflection/Rotation of Earth-directed CMEs 

Suresh Karuppiah, Mateja Dumbovic, Karmen Martinic, Manuela Temmer, Astrid Veronig, Galina Chikunova, Tatiana Podladchikova, Karin Dissauer, Stephan Heinemann, and Bojan Vrsnak

Coronal mass ejections (CMEs) are the major eruptive phenomena that cause various space weather effects. CMEs can be deflected by coronal holes (CH) away or towards the Sun-Earth line depending on their relative location, and also the high speed streams from CH can influence CME propagation. Coronal dimmings which are away or toward the CH may also cause CME deflection. The main aim of our study is to analyse the deflection/rotation of CMEs by tracking them in COR1 and COR2 field of view of STEREO onboard SECCHI with the help of 3D reconstruction Graduated cylindrical shell (GCS) model. We analyse 60 Earth-directed CMEs and their associated low coronal signatures observed in SDO/AIA. In addition, with the help of CATCH tool we study the nearby coronal hole parameters. Furthermore, we analyze the associated coronal dimmings by considering the movement of secondary dimmings towards or away the nearby CH. Out of 60 events, 31 events show deflection/rotation, as we track them from 1.76R to 20.8R. A small fraction of (11%) events show deflection in longitude, and a significant fraction of events show deflection in latitude (38%) and rotation (40%). We discuss these results with respect to the vicinity and direction of coronal holes.

How to cite: Karuppiah, S., Dumbovic, M., Martinic, K., Temmer, M., Veronig, A., Chikunova, G., Podladchikova, T., Dissauer, K., Heinemann, S., and Vrsnak, B.: Deflection/Rotation of Earth-directed CMEs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1395, https://doi.org/10.5194/egusphere-egu23-1395, 2023.

EGU23-1427 | ECS | Orals | ST1.1 | Highlight

Interstellar Neutral Atom Measurements with IBEX and IMAP 

Justyna M. Sokol

Neutral atoms from the interstellar medium around the Sun enter the heliosphere unimpeded by the electromagnetic fields. They bring information about the properties of our interstellar neighborhood, processes at the boundary between the solar and interstellar media, and the direction of the Sun’s motion in the Galaxy. The interstellar neutral atoms of hydrogen, deuterium, helium, neon, and oxygen reach close distances to the Sun where they are probed either by direct detection or remote sensing methods. Here we focus on a direct measurement technique for interstellar neutral atoms of energies from 10 eV to 1 keV on an example of the instruments onboard the Interstellar Boundary Explorer (IBEX) and the follow-up mission the Interstellar Mapping and Acceleration Probe (IMAP, to be launched in 2025). IBEX continuously collects interstellar neutral atom data from the beginning of its operation in 2008 providing a survey over the Solar Cycle 24 despite its observation season being limited during the year. IMAP tracks the beam of interstellar neutrals in the sky throughout the year, which significantly expands scientific opportunities for probing interstellar neutrals from close distances to the Sun. We present the greatest accomplishments of interstellar neutral atom research enabled by IBEX and discuss the science goals in this area for IMAP.

The results are presented in collaboration with scientists and researchers at Southwest Research Institute, the University of Bern, the University of New Hampshire, and Princeton University.

How to cite: Sokol, J. M.: Interstellar Neutral Atom Measurements with IBEX and IMAP, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1427, https://doi.org/10.5194/egusphere-egu23-1427, 2023.

EGU23-1508 | ECS | Orals | ST1.1

Spectroscopic and Imaging Observations of Spatially Extended Magnetic Reconnection in the Splitting of a Solar Filament Structure 

Huidong Hu, Ying D. Liu, Lakshmi Pradeep Chitta, Hardi Peter, and Mingde Ding

On the Sun, Doppler shifts of bidirectional outflows from the magnetic-reconnection site have been found only in confined regions through spectroscopic observations. Without spatially resolved spectroscopic observations across an extended region, the distribution of reconnection and its outflows in the solar atmosphere cannot be made clear. Magnetic reconnection is thought to cause the splitting of filament structures, but unambiguous evidence has been elusive. Here we report spectroscopic and imaging analysis of a magnetic-reconnection event on the Sun, using high-resolution data from the Interface Region Imaging Spectrograph and the Solar Dynamics Observatory. Our findings reveal that the reconnection region extends to an unprecedented length of no less than 14,000 km. The reconnection splits a filament structure into two branches, and the upper branch erupts eventually. Doppler shifts indicate clear bidirectional outflows of ∼100 km s−1, which decelerate beyond the reconnection site. Differential-emission-measure analysis reveals that in the reconnection region the temperature reaches over 10 MK and the thermal energy is much larger than the kinetic energy. This Letter provides definite spectroscopic evidence for the splitting of a solar filament by magnetic reconnection in an extended region.

How to cite: Hu, H., Liu, Y. D., Chitta, L. P., Peter, H., and Ding, M.: Spectroscopic and Imaging Observations of Spatially Extended Magnetic Reconnection in the Splitting of a Solar Filament Structure, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1508, https://doi.org/10.5194/egusphere-egu23-1508, 2023.

EGU23-1629 | Posters virtual | ST1.1

Loading kappa-type distributions in particle simulations 

Seiji Zenitani and Shin'ya Nakano

The kappa distribution is one of the most important velocity distributions in space plasmas. It has both a quasi-Maxwellian core and a suprathermal tail, and it has been considered throughout the heliosphere and magnetospheres. Despite a strong demand for numerical studies in a kappa-distributed plasma, it is not clear how to generate kappa distributions in particle velocities in particle-in-cell (PIC) and Monte Carlo simulations. In this contribution, we present numerical procedures to generate three kappa-type velocity distributions in particle simulations.

First, we review an algorithm for the nonrelativistic kappa distribution. Mathematically, the kappa distribution is equivalent to the multivariate t-distribution [1]. A random variate following the multivariate t-distribution can be generated from the normal and chi-squared distributions. Second, we propose algorithms to generate a kappa loss-cone (KLC) distribution [2], which is often considered in the planetary magnetosphere. We have constructed two procedures. Using the mathematical properties of the beta prime distribution, we can straightforwardly generate the KLC distribution in particle simulations. Third, we propose a procedure for initializing a relativistic kappa distribution. Although the Lorentz factor makes this problem difficult, we have successfully developed a rejection-based algorithm [3]. The rejection part extends an earlier method for a relativistic Maxwell distribution [4], and it accepts particles at the rate of 95% or higher. Our method also use the beta prime distribution. As a result, we can successfully generate a power-law tail of the relativistic kappa distribution.

References:
[1] R. F. Abdul & R. L. Mace, Phys. Plasmas 22, 102107 (2015)
[2] D. Summers & R. M. Thorne, J. Plasma Phys. 53, 293 (1995)
[3] S. Zenitani & S. Nakano, Phys. Plasmas 29, 113904 (2022)
[4] E. Canfield, W. M. Howard, & E. P. Liang, Astrophys. J 323, 565 (1987)

How to cite: Zenitani, S. and Nakano, S.: Loading kappa-type distributions in particle simulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1629, https://doi.org/10.5194/egusphere-egu23-1629, 2023.

EGU23-1714 | Posters on site | ST1.1

Compact Coronagraph (CCOR) Accommodation on GOES-U 

Renee Dudley, Alexander Krimchansky, Sivakumara Tadikonda, Arnaud Thernisien, Rebecca Baugh, and Michael Carter

The CCOR-1 will monitor our Sun’s Coronal Mass Ejections (CMEs).  It will reside on the Sun-Pointing Platform (SPP) of the Geostationary Operational Environmental Satellite (GOES) -U in a geostationary orbit.  As a member of the GOES-R Series of satellites, GOES-U will provide advanced imagery and atmospheric measurements of Earth’s weather, oceans and environment, real-time mapping of total lightning activity, and as well as monitoring of solar activity and space weather. GOES-U is the final satellite in the GOES-R Series, with an expected launch date in April of 2024. 

 

The Compact Coronagraph (CCOR) instrument was designed, built, and tested by the United States Naval Research Laboratory. CCOR-1, the first in a series of coronagraphs, is funded by the National Oceanic and Atmospheric Administration (NOAA), is managed by the National Aeronautics and Space Administration (NASA), and will ultimately be operated by NOAA.  Using a series of images of the Sun’s coronal white-light, scientists at NOAA’s Space Weather Prediction Center (SWPC) and National Centers for Environmental Information (NCEI) can determine the size, velocity, and density of these CMEs.  This information can then be used to assess and prepare for potential impacts of these solar storms on infrastructure here on Earth, as well as assets in space. 

 

CCOR-1 has completed instrument-level Integration and Testing (I&T), delivered to the GOES-U satellite integrator and is now mechanically integrated with the spacecraft. The integrated GOES-U satellite has completed Spacecraft-level Thermal Vacuum testing and is expected to complete all the remaining Spacecraft I&T activities by the EGU Conference date.

 

This paper presents the details on the CCOR-1 instrument, its integration onto the GOES-U satellite bus, and the expected performance.

How to cite: Dudley, R., Krimchansky, A., Tadikonda, S., Thernisien, A., Baugh, R., and Carter, M.: Compact Coronagraph (CCOR) Accommodation on GOES-U, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1714, https://doi.org/10.5194/egusphere-egu23-1714, 2023.

EGU23-1807 | Posters on site | ST1.1

From the Solar Limb and Out: Results from the Wide-Field EUV Image Campaigns with GOES/SUVI 

Sivakumara K. Tadikonda, Daniel B. Seaton, Christian Bethge, Amir Caspi, Melissa Dahya, Craig DeForest, Matthew P. Garhart, J. Marcus Hughes, Alexander Krimchansky, Pamela C. Sullivan, Monica Todirita, and Matthew West

Traditional approaches to tracking solar outflows for space weather forecasting rely primarily on coronagraph images, which generally observe the solar corona above a minimum height of about 2.5 solar radii. EUV images have been widely used to characterize features on the solar disk, but the limited fields of view of most current EUV imagers have prevented their use for tracking outflows through the inner and middle coronae. A series of off-point campaigns with the GOES 16-18 Solar Ultraviolet Imager (SUVI) between 2018 and 2022 from three Flight Models have provided an opportunity to assess the value of extended EUV images for space weather forecasting applications. These new results demonstrate that wide field-of-view EUV images are useful for characterizing the early onset of eruptive events and tracking smaller outflow into the solar wind. They also reveal the origins of shocks that are known to accelerate particles and drive solar energetic particle (SEP) events. Because CMEs generally experience the bulk of their acceleration below the height of white light coronagraphic observations, these images provide information about the origins of these events that has not been available traditionally. Together with coronagraphic measurements, EUV images provide the continuous views needed to connect CMEs back to their source regions. Here, we present these new SUVI observations and discuss their potential use in space weather operations.

How to cite: Tadikonda, S. K., Seaton, D. B., Bethge, C., Caspi, A., Dahya, M., DeForest, C., Garhart, M. P., Hughes, J. M., Krimchansky, A., Sullivan, P. C., Todirita, M., and West, M.: From the Solar Limb and Out: Results from the Wide-Field EUV Image Campaigns with GOES/SUVI, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1807, https://doi.org/10.5194/egusphere-egu23-1807, 2023.

EGU23-2095 | Orals | ST1.1 | Highlight

Constraints on the IBEX Ribbon's Origin from its Evolution over a Solar Cycle 

Eric Zirnstein, Pawel Swaczyna, Maher Dayeh, and Jacob Heerikhuisen

The heliosphere surrounding our solar system is formed by the interaction between the solar wind and the local interstellar medium as the Sun moves through interstellar space. With dimensions on the order of hundreds to potentially thousands of au, it is difficult to determine the 3D structure of the heliosphere and the properties of the plasma surrounding it. However, observations of energetic neutral atoms (ENAs), which are created as a product of charge exchange between interstellar neutrals and energetic plasma ions, allow us to remotely discern the properties of the distant heliospheric boundaries.

NASA's Interstellar Boundary Explorer (IBEX) mission, a small explorer spacecraft which has been measuring ENA fluxes at ~0.5-6 keV for more than a solar cycle, discovered a “ribbon” of enhanced ENA fluxes forming a narrow, circular band across the sky. While it is generally believed that the ribbon is formed from secondary ENAs from outside the heliopause, a source of ENAs that is separate from the globally distributed flux (GDF) across the sky, it is not clear exactly how the parent ions outside the heliopause evolve over time before they become ribbon ENAs. To help solve this issue, we present recent developments in modeling the evolution of the ribbon over a solar cycle, under different pitch angle scattering assumptions. We hypothesize that simulating the evolution of the ribbon under differing scattering rates may help discern the physical mechanisms responsible for creating the ribbon observed by IBEX. We compare our modeling results to IBEX data where the ribbon was separated from the GDF using spherical harmonic decomposition, analyzing the evolution of the ribbon’s intensity and geometry as a function of ENA energy.

How to cite: Zirnstein, E., Swaczyna, P., Dayeh, M., and Heerikhuisen, J.: Constraints on the IBEX Ribbon's Origin from its Evolution over a Solar Cycle, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2095, https://doi.org/10.5194/egusphere-egu23-2095, 2023.

EGU23-2100 | Orals | ST1.1 | Highlight

Update on the Interstellar Mapping and Acceleration Probe (IMAP) Mission 

David McComas

This talk provides an overview of the Interstellar Mapping and Acceleration Probe (IMAP), what we hope and expect to learn from it, and where we are in the development of the mission. IMAP is currently in Phase C and is slated to launch in early 2025. IMAP simultaneously investigates two of the most important and intimately coupled research areas in Heliophysics today: 1) the acceleration of energetic particles and 2) the interaction of the solar wind with the local interstellar medium. IMAP’s ten instruments provide a complete set of observations to simultaneously examine the particle injection and acceleration processes at 1 AU while remotely dissecting the global heliospheric interaction and its response to particle populations generated through these processes. For more information about IMAP, see McComas, D.J. et al., Interstellar mapping and acceleration Probe (IMAP): A New NASA Mission, Space Science Review, 214:116, doi:10.1007/s11214-018-0550-1, 2018.

How to cite: McComas, D.: Update on the Interstellar Mapping and Acceleration Probe (IMAP) Mission, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2100, https://doi.org/10.5194/egusphere-egu23-2100, 2023.

EGU23-2300 | Posters on site | ST1.1

3D MHD Modeling of an Observed Solar Prominence 

Tibor Torok, Emily I. Mason, Cooper Downs, Roberto Lionello, and Viacheslav S. Titov

The physical mechanisms by which solar prominences (or filaments) form are still not well understood. The presently favored scenario invokes the evaporation of chromospheric plasma via localized heating at the footprints of a magnetic flux rope (MFR) or sheared arcade, and the subsequent condensation of this plasma in the corona due to thermal non-equilibrium (TNE). This scenario has been modeled extensively in one-dimensional (1D) hydrodynamic simulations along static magnetic field lines, and recently also in fully 3D magnetohydrodynamic (MHD) simulations, using idealized MFR configurations. However, such configurations lack the complexity of real prominence magnetic fields. In this presentation, we first briefly discuss our prominence modeling approach for the case of an idealized 3D MFR configuration. We then report on our recent attempts to employ data-constrained MHD simulations to model the formation of observed filaments. To this end, we selected the filament that erupted in a spectacular manner on June 7, 2011 in NOAA AR 11226. To model its formation, we first develop a semi-realistic ("thermodynamic MHD") model of the solar corona, using SDO/HMI data as boundary condition for the magnetic field. Next, we insert an MFR constructed with the RBSL method (Titov et al., 2018) into the source region of the filament. Finally, we impose localized heating at the MFR's footprints. We compare our results with our idealized simulations and discuss the challenges that arise once realistic cases are considered.

How to cite: Torok, T., Mason, E. I., Downs, C., Lionello, R., and Titov, V. S.: 3D MHD Modeling of an Observed Solar Prominence, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2300, https://doi.org/10.5194/egusphere-egu23-2300, 2023.

EGU23-2360 | Orals | ST1.1 | Highlight

Recent advancements on particle acceleration at collisionless shocks 

Silvia Perri

Energetic particles represent an important component of the plasma in the heliosphere. Spacecraft observations have detected energetic particles accelerated at impulsive events in the solar corona and at interplanetary shocks. Fluctuations in energetic particle fluxes are related to solar activity and to magnetic turbulence in the interplanetary medium. Thanks to in-situ satellite observations, numerical simulations, and theoretical models, our knowledge on the particle acceleration processes involved has advanced significantly in recent years. Here we review new developments on particle acceleration at collisionless shocks, in particular in relation with the transport properties of supra-thermal particles, as inferred from the analysis of particle fluxes, addressing that anomalous, superdiffusive transport is common in the interplanetary medium. A link between the results obtained from the in-situ diagnostic, used for studying energetic particle transport and acceleration, and remote observations of astrophysical shocks will be discussed.

How to cite: Perri, S.: Recent advancements on particle acceleration at collisionless shocks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2360, https://doi.org/10.5194/egusphere-egu23-2360, 2023.

The dynamics of small (few hundred nm) charged interstellar dust particles entering the heliosphere is affected by the heliospheric magnetic field and in particular by the heliospheric current sheet. To estimate the flux distribution of the dust particles inside the heliosphere we simulate numerically the trajectories of moderately large samples (10^4 particles) of small charged dust grains with starting points outside the heliopause. The simulations are repeated for different choices of the initial time. We use the semi-analytical model of the heliosphere that combines a simplified time-stationary description of the plasma flow in the heliosphere and the outer heliosheath with the time-dependent magnetic field carried passively by the flow. The form of the heliospheric current sheet is determined by our choice of the time-dependent magnetic polarity structure at the surface of the rotating Sun. 

How to cite: Mann, I. and Czechowski, A.: Interstellar dust in the model heliosphere: effects of  time-dependent heliospheric current sheet, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2860, https://doi.org/10.5194/egusphere-egu23-2860, 2023.

EGU23-3015 | Orals | ST1.1

On the Open Solar Magentic Flux Problem 

Charles Arge, Andrew Leisner, Samantha Wallace, and Carl Henney

The solar magnetic fields emerging from the photosphere are comprised of a combination of “closed” and “open” fields. The closed magnetic field lines are defined as those having both ends rooted in the solar surface and not extending beyond the critical point, while the “open” field lines are those having one end that extends out into interplanetary space with the other end rooted at the Sun’s surface. Of course, there are no truly “open” magnetic field lines, and those that are dragged out into interplanetary space by the solar wind eventually close in the far reaches of the outer heliosphere. Since the early 2000’s, the amount of total unsigned open magnetic flux estimated by coronal models have been in significant disagreement with in situ spacecraft observations, especially during solar maximum, with factors of two or more differences not uncommon. Estimates of total open unsigned magnetic flux using coronal hole observations (e.g., using EUV or He 10830) are in general agreement with the coronal model results and thus are in similar disagreements with in situ observations. Several possible sources producing these discrepancies have been postulated over the years such as problems with the photospheric magnetic field measurements, underestimates of the polar field strengths, coronal mass ejection (CME) magnetic fields that are still closed but counted as open, the time-dependent nature of the magnetic field (i.e., the opening and closing of magnetic fields), and the manner in which in situ observations are used to estimate total open unsigned magnetic flux. This paper provides a brief review of the problem and some of the proposed explanations to account for the discrepancies. It concludes with compelling new evidence that appears to largely resolve the problem.

How to cite: Arge, C., Leisner, A., Wallace, S., and Henney, C.: On the Open Solar Magentic Flux Problem, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3015, https://doi.org/10.5194/egusphere-egu23-3015, 2023.

EGU23-3035 | Orals | ST1.1 | Highlight

First results of the Chinese Ha Solar Explorer - CHASE mission 

Chuan Li, Cheng Fang, Mingde Ding, Pengfei Chen, and Zhen Li

The Chinese Hα Solar Explorer (CHASE) was successfully launched on 14 October 2021 as the first solar space mission of China National Space Administration (CNSA). The scientific payload of the CHASE satellite is the Hα Imaging Spectrograph (HIS). The CHASE/HIS acquires seeing-free spectroscopic observations of the whole solar disk at three spectral lines of Si I (6560.6 Å), Hα (6562.8 Å) and Fe I (6569.2 Å) which are formed at different heights of the photosphere and chromosphere. A full-Sun scanning takes only 46 seconds, with a spectral sampling of 0.024 Å and a spatial resolution of 1.2 arcsec. Since its launch and in-orbit calibrations, the performance of the CHASE mission is excellent and meets the pre-launch expectations. The FITS formatted science data are now available to the community through the Solar Science Data Center of Nanjing University (SSDC-NJU, https://ssdc.nju.edu.cn). Here we introduce the CHASE science data and the calibration procedures. The first series of scientific studies of the CHASE mission are also presented.

How to cite: Li, C., Fang, C., Ding, M., Chen, P., and Li, Z.: First results of the Chinese Ha Solar Explorer - CHASE mission, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3035, https://doi.org/10.5194/egusphere-egu23-3035, 2023.

EGU23-3166 | Orals | ST1.1

Generation and Decay of Reconnecting Current Structures Downstream of the Bow Shock: 3D Hybrid Simulations 

Imogen L. Gingell, Steven J. Schwartz, Harald Kucharek, Charles J. Farrugia, Laura J. Fryer, James Plank, and Karlheinz J. Trattner

Observations of Earth’s bow shock and magnetosheath have shown that magnetic reconnection occurs within these regions at thin current sheets, typically arising from turbulence and plasma instabilities in the shock transition layer. Broad observational surveys of these regions have shown that, somewhat surprisingly, the prevalence of reconnecting current structures may not be strongly dependent on the shock Mach number or the angle between the upstream magnetic field and shock normal (θBn), despite quasi-parallel shocks typically exhibiting more disordered and non-stationary structure. To investigate how shock reconnection manifests across different parameters, we perform a series of two- and three-dimensional hybrid (fluid electron, kinetic ion) particle-in-cell simulations across a broad range of Mach numbers and orientations. These simulations isolate ion-scale mechanisms for reconnection in the shock, principally those driven by ion-ion beam instabilities in the foot and foreshock. For 2D simulations, we show that reconnection via these ion-driven mechanisms is strongly constrained to quasi-parallel shocks. However, downstream of quasi-parallel shocks, we find that the decay rate of closed-field regions, and hence thin current sheets, is not strongly dependent on upstream shock parameters. We also explore the differences that arise in shock structure, the generation of reconnecting current structures, and their decay rates for three-dimensional simulations.

How to cite: Gingell, I. L., Schwartz, S. J., Kucharek, H., Farrugia, C. J., Fryer, L. J., Plank, J., and Trattner, K. J.: Generation and Decay of Reconnecting Current Structures Downstream of the Bow Shock: 3D Hybrid Simulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3166, https://doi.org/10.5194/egusphere-egu23-3166, 2023.

EGU23-3536 | ECS | Orals | ST1.1

Magnetic connectivity from the Sun to the Earth: Impact of the magnetic modelling and input magnetic map 

Barbara Perri, Silke Kennis, Michaela Brchnelova, Tinatin Baratashvili, Blazej Kuzma, Fan Zhang, Andrea Lani, and Stefaan Poedts

Connectivity between our star and our planet is a huge but necessary challenge. Indeed, remote-sensing instruments allow us to observe with great details the surface of the Sun, while in-situ measurements let us see the consequences at Earth. However, it it not always easy to understand the link between the two, thus preventing us from understanding the propagation of physical effects. One way to chase this connection is to use the magnetic field: although not visible, open magnetic field bathes the entire heliosphere, and has a major influence on plasma and particle events such as CMEs or flares. We can typically use numerical simulations to estimate the magnetic field lines pattern, and thus help connecting remote-sensing with in-situ observations.

 

In this study, we will present our computation of the magnetic connectivity through the heliosphere by coupling the MHD codes COCONUT for the solar corona and EUHFORIA for the inner heliosphere. MHD codes are usually too slow to compute connectivity on a near-real time cadence, but this chain of model can be optimised to run in less than 6 hours, which allows refined tracking within a single day. We will explain how the coupling between the code operates, as it effects the tracing of the magnetic field lines. We will also explain how to provide uncertainties with this method. We will first show the validation of our method by comparison with PFSS and wind ballistic mapping, for both polar and equatorial open coronal holes, on several test cases that were already used in previous studies. This will allow us to discuss the impact of the magnetic modelling on the connectivity estimation. Finally, we will also discuss the impact of the input magnetic map by comparing 20 different runs for the same Carrington rotation at minimum of activity, based on various maps from different providers.

How to cite: Perri, B., Kennis, S., Brchnelova, M., Baratashvili, T., Kuzma, B., Zhang, F., Lani, A., and Poedts, S.: Magnetic connectivity from the Sun to the Earth: Impact of the magnetic modelling and input magnetic map, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3536, https://doi.org/10.5194/egusphere-egu23-3536, 2023.

EGU23-3939 | Orals | ST1.1

Open Magnetic Flux in the Time-Evolving Corona 

Jon A. Linker, Emily Mason, Roberto Lionello, Cooper Downs, Ronald Caplan, Viacheslav Titov, Pete Riley, and Marc DeRosa

Models of the Solar Corona, ranging from potential field source surface (PFSS) to magnetohydrodynamic (MHD), typically provide a steady-state representation for a given time period, based on a single photospheric magnetic map.  However, the Sun's magnetic flux is in truth constantly evolving, and these changes in the flux affect the structure and dynamics of the corona and heliosphere.  The dynamics may be crucial to understanding solar wind properties.  A key question in the "Open Flux Problem" is whether the nature of open magnetic flux is adequately captured by steady-state PFSS and MHD models.  We describe an approach to evolutionary models of the corona and solar wind, using time-dependent boundary conditions.  We use the Lockheed Surface Flux Transport (SFT) model to evolve the surface magnetic fields, which in turn drive the coronal evolution.  The simulations are performed with the MAS thermodynamic Wave-Turbulence Driven (WTD) model for a month of simulated time.  We use the simulated observables derived from the simulation to explore the evolution of coronal structure (e.g., coronal hole boundaries).  We investigate the open magnetic flux in the model and contrast the results with MHD solutions using static magnetic flux boundaries at selected times.

How to cite: Linker, J. A., Mason, E., Lionello, R., Downs, C., Caplan, R., Titov, V., Riley, P., and DeRosa, M.: Open Magnetic Flux in the Time-Evolving Corona, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3939, https://doi.org/10.5194/egusphere-egu23-3939, 2023.

EGU23-4472 | Posters on site | ST1.1 | Highlight

An overview of the planetary theory of solar activity variability and its importance for understanding climate oscillations 

Antonio Bianchini and Nicola Scafetta

The complex dynamics of solar activity appear to be controlled by a number of individual oscillations from the monthly to the millennial scales, the most well-known of which is the 11-year Schwabe sunspot cycle. These oscillations are important also because many of them characterize the oscillations found in the climate of the Earth and could be used for climate change forecast purposes. However, the physical cause of the solar oscillations is still debated. Commenting on the origin of the 11-year sunspot cycle, Johann Rudolf Wolf (1859, MNRAS 19, 85–86) conjectured that “the variations of spot frequency depend on the influences of Venus, Earth, Jupiter, and Saturn.” There are only two options: either the solar activity changes are solely controlled by internal solar dynamo mechanisms or the solar dynamo itself is partially synchronized by external harmonic planetary forcings. The former hypothesis is today shared by the majority of solar scientists; the latter has been recently advocated by an increasing minority of solar scientists, and the debate is still going on. Here we overview the numerous pieces of evidence supporting a planetary theory of solar activity variability by demonstrating that the many planetary harmonics and the orbital invariant inequalities that characterize the planetary motions of the solar system from the monthly to the millennial time scales are not randomly distributed but clearly tend to cluster around some specific values that also match those of the main solar activity cycles. We also show that planetary models have even been able to predict the time phase of the solar oscillations including the Schwabe 11-year sunspot cycle. Although planetary tidal forces are weak, we review a number of mechanisms that could explain how the solar structure and the solar dynamo could get tuned to the planetary motions. In particular, we discuss how the effects of the weak tidal forces could be significantly amplified in the solar core by an induced increase in the H-burning. Mechanisms modulating the electromagnetic and gravitational large-scale structure of the planetary system are also discussed.

Main Reference:

Scafetta N and Bianchini A (2022) The Planetary Theory of Solar Activity Variability: A Review. Front. Astron. Space Sci. 9:937930. doi: 10.3389/fspas.2022.937930

Scafetta, N. (2020). Solar Oscillations and the Orbital Invariant Inequalities of the Solar System. Sol. Phys. 295, 33. doi:10.1007/s11207-020-01599-y

How to cite: Bianchini, A. and Scafetta, N.: An overview of the planetary theory of solar activity variability and its importance for understanding climate oscillations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4472, https://doi.org/10.5194/egusphere-egu23-4472, 2023.

The emergence of magnetic flux in the Sun can lead to the formation of active regions with highly complex magnetic fields, evident by δ-spots, filaments, and sigmoids. These regions are often the sources of major flares and coronal mass ejections (CMEs) and monitoring their evolution is crucial for a deeper understanding of these phenomena as well as space weather applications. To this end, high-quality observations of the photospheric magnetic field are routinely used to derive parameters and physical magnitudes, and quantify the magnetic complexity of active regions. Thus, we know that eruptive active regions are associated with highly non-potential magnetic field configurations, with strong electric currents and huge amounts of free magnetic energy and helicity. This talk reviews recent efforts to parameterize this non-potentiality of active regions and discusses ongoing and future work on developing new and improved parameters suitable for flare and CME prediction. It further focuses on the evolution of net electric currents in active regions, from their emergence to eruption. The significance of net electric currents on flare and CME prediction and new ways to utilize them in order to produce improved eruptivity parameters and understand solar eruptions will be discussed.

How to cite: Kontogiannis, I.: Parameterizing the evolution of active regions from emergence to eruption. Recent results and future work., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5436, https://doi.org/10.5194/egusphere-egu23-5436, 2023.

EGU23-5509 | ECS | Posters on site | ST1.1

Laboratory calibration of low-energy ENA instruments for space science 

Jonathan Gasser, André Galli, and Peter Wurz

Imaging space plasmas via Energetic Neutral Atoms (ENA) is a widely used technique to study space plasma population ranging from the Earth’s magnetosphere all the way to the interstellar medium. Laboratory calibration against a known ENA beam source is a key element in the development and testing of spaceborne ENA imaging instruments. For ENA instruments operating at energies below about 1 keV, an ion beam source cannot be used for the instrument calibration, as ion trajectories are distorted through electromagnetic fields inside the ENA instrument whereas neutrals are not. The MEFISTO laboratory test facility at the University of Bern is well suited to carry out such ENA instrument calibrations: It provides neutral atom beams of any species from H to heavy elements at the relevant low-energy range from 3 keV down to 10 eV. MEFISTO is equipped with a large vacuum test chamber and an electron-cyclotron resonance ion source (ECRIS) for the production of a primary ion beam. Ion beam neutralization is performed with a dedicated neutralization stage via grazing scattering surface neutralization. This neutralization method introduces some uncertainty to the neutral beam energy and comes with species and energy dependent throughput.

Therefore, neutral beam calibrations have been conducted against a novel Absolute Beam Monitor (ABM), which serves as a primary calibration standard in the low-energy ENA range. Calibrated neutral beam fluxes and energies have been obtained for species of interest to interstellar, heliosphere and planetary science, including H, D, He, O, Ne neutral beams. The recently upgraded 5-axis movable hexapod table in the test chamber allows for precise motion and rotation of instrument under test relative to ENA calibration beam. These measures allow us to carry out thorough ENA instrument calibrations against a well-characterized low-energy neutral atoms beam source.

How to cite: Gasser, J., Galli, A., and Wurz, P.: Laboratory calibration of low-energy ENA instruments for space science, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5509, https://doi.org/10.5194/egusphere-egu23-5509, 2023.

EGU23-5688 | Posters on site | ST1.1

Comparison of heliosphere models with IBEX-Lo observations of Energetic Neutral Atoms at 50 eV - 2 keV energy 

André Galli, Igor I. Baliukin, Marc Kornbleuth, Stephen A. Fuselier, Justyna M. Sokół, and Merav Opher

The Interstellar Boundary Explorer (IBEX) is a NASA satellite in Earth’s orbit, observing both interstellar neutral atoms entering the heliosphere and energetic neutral atoms (ENAs) from the interstellar boundaries from roughly 10 eV to 6 keV. IBEX consists of two ENA imagers: IBEX-Lo covers the low energy range from 10 eV to 2 keV, IBEX-Hi covers ENA energies between 500 eV and 6 keV (corresponding roughly to solar wind energy).

ENA imaging is an indispensable tool in space physics. ENAs carry information on the plasma region where they were created that can be deciphered by analysis of the species, intensity, spatial distribution, and energy spectrum. The ENA intensity measured by a remote observer, such as IBEX, is a line of sight integral over potentially many different ion populations and local neutral atom densities. Thus, to derive properties of the heliosphere and of its plasma populations from such ENA measurements, they must be compared with the predictions of heliosphere models.

The majority of ENA model comparisons with IBEX observations so far were restricted to IBEX-Hi data. In this study, we present the first comparison of IBEX-Lo data with heliosphere models over one full solar cycle (using the tabulated energy spectra in Galli et al. 2022, http://dx.doi.org/10.3847/1538-4365/ac69c9). We use heliosphere models developed at the Moscow University and Boston University in this study. The comparison concentrates on the energy spectra of heliospheric ENAs originating from regions in the sky (such as Voyager 1, Voyager 2, South Pole, North Pole, and heliosphere downwind direction) that are cardinal directions for the comparison of the ENA data and the global heliosphere models.

This study is a part of the Research Team “Global Structure of the Heliosphere” within the SHIELD NASA DRIVE Science Center.

How to cite: Galli, A., Baliukin, I. I., Kornbleuth, M., Fuselier, S. A., Sokół, J. M., and Opher, M.: Comparison of heliosphere models with IBEX-Lo observations of Energetic Neutral Atoms at 50 eV - 2 keV energy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5688, https://doi.org/10.5194/egusphere-egu23-5688, 2023.

EGU23-6946 | ECS | Orals | ST1.1 | Highlight

Relations between coronal shock waves properties and acceleration of solar energetic particles 

Manon Jarry, Alexis Rouillard, Illya Plotnikov, Athanasios Kouloumvakos, and Alexander Warmuth

The mechanisms that produce solar energetic particles (SEPs) are still highly debated but coronal shock waves have been proposed as efficient particle accelerators that may be implicated in the production of SEPs.
An analysis of 32 Coronal Mass Ejections (CMEs) that produced strong pressure waves in the solar corona during their eruption has been done. For each event Kouloumvakos et al. (2019) exploited remote-sensing observations from multiple vantage points to reconstruct their 3-D ellipsoidal shapes. This catalogue of shock waves provides important statistical information on their kinematic evolution that we report in Jarry et al. (2023) together with their relation to X-ray flaring activitiy.
Different SEPs exhibit significant spectral and compositional variability. We looked for links between the composition of SEPs including abundance ratios (such as Fe/O) and shock parameters (Mach number, shock geometry, ..) that typically evolves rapidly along the magnetic field lines connected to the spacecraft recording SEPs.
This work was funded by the H2020 SERPENTINE project.

How to cite: Jarry, M., Rouillard, A., Plotnikov, I., Kouloumvakos, A., and Warmuth, A.: Relations between coronal shock waves properties and acceleration of solar energetic particles, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6946, https://doi.org/10.5194/egusphere-egu23-6946, 2023.

EGU23-7823 | ECS | Orals | ST1.1

Iron Heating Across a Shock Observed by Solar Orbiter's Heavy Ion Sensor 

Benjamin L. Alterman, Stefano Livi, Christopher Owen, Philippe Louarn, Roberto Bruno, Raffaella D'Amicis, Jim Raines, Susan Lepri, Sarah Spitzer, Ryan M. Dewey, Christopher M. Bert, Lynn Kistler, Antoinette Galvin, Yeimy Rivera, Tim Horbury, Domenico Trotta, Heli Hietala, Ed Fauchon-Jones, Irena Gershkovich, and Daniel Verscharen and the SWA and MAG Teams

Ion mass-per-charge and shock geometry determine both shock injection and the number of times a charged particle is reflected across a shock. As such, they govern charged particle acceleration and heating at shock. Solar Obiter’s Heavy Ion Sensor (HIS) observed a quasi-parallel CME-driven shock on March 11, 2022. HIS has sufficient time, mass, and charge resolution that it measured individual distributions of iron 8+ through 12+ on the variable timescale of 2 to 5 minutes. Using these 1D velocity distribution functions (VDFs), we report that the thermal portion of the Fe distribution heats across the shock, that this heating increases with Q/M, and the heating increases with distance downstream from the shock.

How to cite: Alterman, B. L., Livi, S., Owen, C., Louarn, P., Bruno, R., D'Amicis, R., Raines, J., Lepri, S., Spitzer, S., Dewey, R. M., Bert, C. M., Kistler, L., Galvin, A., Rivera, Y., Horbury, T., Trotta, D., Hietala, H., Fauchon-Jones, E., Gershkovich, I., and Verscharen, D. and the SWA and MAG Teams: Iron Heating Across a Shock Observed by Solar Orbiter's Heavy Ion Sensor, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7823, https://doi.org/10.5194/egusphere-egu23-7823, 2023.

EGU23-8250 | ECS | Orals | ST1.1

On the Transmission of Turbulence Across Interplanetary Shocks: Observations and Theory 

Alexander Pitna, Gary Zank, Masaru Nakanotani, Lingling Zhao, Laxman Adhikari, Jana Šafránková, and Zdeněk Němeček

Collisionless magnetohydrodynamic shocks are ubiquitous in solar wind and in other space plasmas. They serve as natural sites where charged particles can be accelerated to supra-thermal energies via various Fermi acceleration mechanisms. Upstream and downstream fluctuations play a key role in these processes because they can act as scatter centers. Furthermore, the downstream turbulent plasma of strong shocks driven by coronal mass ejections can enhance the coupling of this plasma with the Earth’s magnetosphere. Understanding of how the fluctuations are transmitted across the shocks can provide an invaluable insight into many shock related studies.

In this paper, we investigate the interaction of fast forward (FF) shocks with magnetic island/flux rope mode fluctuations. We employ a recently developed framework of the Zank et al. (2021) transmission model. We analyze 378 FF shocks observed by the Wind spacecraft with varying upstream conditions and Mach numbers. We estimate upstream and downstream power spectra within one-hour intervals adjacent to the shock front and we calculate theoretically predicted downstream power spectrum. We analyze closely the difference between the observed and theoretically predicted spectra. On average, the model predicts the spectra with very good accuracy. We argue that large statistical spread of this difference is given mainly by the statistical uncertainties in the shock compression ratio, upstream power spectrum and by the turbulent evolution of fluctuations in the downstream region. Finally, our findings also suggest that Zank et al. (2021) model may estimate the downstream levels of fluctuations accurately even for a wider range of shocks than it was originally meant for.

How to cite: Pitna, A., Zank, G., Nakanotani, M., Zhao, L., Adhikari, L., Šafránková, J., and Němeček, Z.: On the Transmission of Turbulence Across Interplanetary Shocks: Observations and Theory, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8250, https://doi.org/10.5194/egusphere-egu23-8250, 2023.

EGU23-8760 | Posters on site | ST1.1

Observations of energetic particles at interplanetary shocks with Solar Orbiter 

Domenico Trotta, Timothy Horbury, Heli Hietala, Nina Dresing, Rami Vainio, Emilia Kilpua, Andrew Dimmock, Xochitl Blanco-Cano, David Lario, Andriy Koval, Robert Wimmer-Schweingruber, Lars Berger, and Liu Yang

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

Under 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. We present a comprehensive identification of such shocks, highlighting their typical parameters.

We then study a strong shock showing novel dispersive signals in the suprathermal particle fluxes observed by the Solar Orbiter SupraThermal Electron and Proton sensor. These are probably due to irregular injection of particles to suprathermal energies along the shock front, as inferred using the Solar Orbiter in-situ observations and self-consistent, kinetic modelling of the shock transition.

How to cite: Trotta, D., Horbury, T., Hietala, H., Dresing, N., Vainio, R., Kilpua, E., Dimmock, A., Blanco-Cano, X., Lario, D., Koval, A., Wimmer-Schweingruber, R., Berger, L., and Yang, L.: Observations of energetic particles at interplanetary shocks with Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8760, https://doi.org/10.5194/egusphere-egu23-8760, 2023.

EGU23-8789 | ECS | Posters on site | ST1.1

FARM: Combined surface flux transport and helioseismic Far-side Active Region Model 

Stephan G. Heinemann, Dan Yang, Jens Pomoell, Charles N. Arge, Shaela I. Jones, and Laurent Gizon

Synoptic magnetic field data usually serves as the boundary condition for simulations of the global magnetic field; however, it has been shown that these data suffer from an “aging effects” as the longitudinal 360° information can only be obtained over the course of one solar rotation. To avoid this, we use advanced magnetograms produced by feeding near-side HMI/SDO magnetograms and far-side helioseismic active regions into a modified surface flux transport model to improve the modeling of the far-side magnetic configuration. This allows for a more accurate description of the state of the global magnetic field and thus for an improved forecasting of solar wind parameters. We use potential field source surface (PFSS) and WSA modeling as well as the EUropean Heliospheric FORecasting Information Asset (EUHFORIA) to derive the coronal magnetic field configuration and the heliospheric solar wind structure as well as discuss the changes caused by the implementation of far-side active regions into magnetic field maps. Modeled solar wind results are found to be in good agreement with far-side in-situ measurements taken by various instruments. We can show the importance of considering not only the solar near-side but also the far-side to accurately model the heliosphere in which solar transients are propagated.

How to cite: Heinemann, S. G., Yang, D., Pomoell, J., Arge, C. N., Jones, S. I., and Gizon, L.: FARM: Combined surface flux transport and helioseismic Far-side Active Region Model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8789, https://doi.org/10.5194/egusphere-egu23-8789, 2023.

EGU23-8849 | Orals | ST1.1 | Highlight

Prediction of even and odd sunspot cycles: implications for cycles 25 and 26 

Timo Asikainen and Jani Mantere

Prediction of sunspots has been an everlasting interest in the space science community since the discovery of the sunspot cycle. The sunspot number is an indirect indicator of many different solar phenomena, e.g., total and spectral solar radiation, coronal mass ejections, solar flares and magnetic active regions. Its cyclic variation can even be used as a pacemaker to time different aspects of solar activity, solar wind and resulting geomagnetic variations. Therefore, there is considerable practical interest in predicting the evolution of future sunspot cycle(s). This is especially true in today’s technological society where space hazards pose a significant threat, e.g., to satellites, communications and electric grids on ground have been recognized. Another interest to predicting sunspots arises from the relatively recently recognized influences of variable solar radiation and solar wind activity on Earth’s climate system.

There are a variety of methods developed for predicting sunspots ranging from statistical methods to intensive physical simulations. Some of the most successful, yet relatively simple, methods are based on finding precursors that serve as indicators for the strength of the coming solar cycle. These methods are often based on statistics of all past solar cycles. However, most of these methods do not typically take into account the 22-year Hale cycle of solar magnetism, which is well known in different solar and geomagnetic phenomena.

Here we study the prediction of even and odd numbered sunspot cycles separately, thereby taking into account the Hale cyclicity of solar magnetism. We first show that the temporal evolution and shape of all sunspot cycles are extremely well described by a simple parameterized mathematical expression. We find that the parameters describing even sunspot cycles can be predicted quite accurately using the sunspot number 41 months prior to sunspot minimum as a precursor. The parameters of the odd cycles can be best predicted with geomagnetic maximum geomagnetic aa index close to fall equinox within a 3-year window preceding the sunspot minimum. Cross-validated hindcasts indicate that our method has a very good prediction accuracy. For the coming sunspot cycle 25 we predict an amplitude of 171 +/- 23 and the end of the cycle in September 2029 +/- 1.9 years. We are also able to make a rough prediction for cycle 26 based on the predicted cycle 25. While the uncertainty for the cycle amplitude is large we estimate that the cycle 26 will likely be stronger than cycle 25. These results suggest an increasing trend in solar activity for the next two decades.

How to cite: Asikainen, T. and Mantere, J.: Prediction of even and odd sunspot cycles: implications for cycles 25 and 26, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8849, https://doi.org/10.5194/egusphere-egu23-8849, 2023.

EGU23-9785 | Posters on site | ST1.1

Waves upstream of interplanetary shocks 

Xochitl Blanco-Cano, Domenico Trotta, Heli Hietala, Primoz Kajdic, Diana Rojas-Castillo, Andrew Dimmock, Tim Horbury, Rami Vainio, and Lan Jian

Interplanetary (IP) shocks can be driven in the solar wind by fast coronal mass ejections and by the interaction of fast solar wind with slow streams of plasma. These shocks can be preceded by extended waves and suprathermal ion foreshocks. Shocks characteristics as well as the level of wave activity near them change as they propagate through the heliosphere and this can impact particle acceleration, and modify the ambient solar wind. In this work we study IP shock evolution and the wave modes upstream of them using a multispacecraft approach with data of Solar Orbiter, STEREO, Parker Solar Probe and Wind. We find that upstream regions can be permeated by whistler waves (f ~ 1 Hz) and/or ultra low frequency (ULF) right-handed waves (f~10-2–10-1 Hz). While whistlers appear to be generated at the shock, the origin of ULF waves is most probably associated with local kinetic ion instabilities. In contrast with planetary bow shocks, most IP shocks have a small Mach number (<4) and most of the upstream waves studied here are mainly transverse and steepening rarely occurs.

 

How to cite: Blanco-Cano, X., Trotta, D., Hietala, H., Kajdic, P., Rojas-Castillo, D., Dimmock, A., Horbury, T., Vainio, R., and Jian, L.: Waves upstream of interplanetary shocks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9785, https://doi.org/10.5194/egusphere-egu23-9785, 2023.

EGU23-11192 | Posters on site | ST1.1

Ion reflection observed at high Mach number interplanetary shocks: Solar Orbiter observations 

Andrew Dimmock, Michael Gedalin, Domenico Trotta, Ahmad Lalti, Daniel Graham, Yuri Khotyaintsev, Rami Vainio, Xochitl Blanco-Cano, Primoz Kajdič, and Christopher Owen

Collisionless shocks exist across diverse plasma environments. Examples are supernova remnants, comets, near planets, and interplanetary (IP) shocks in the solar wind. As the shock Mach number increases, so does the complexity of the ion distribution functions at the shock front due to features such as whistler precursors, ion reflection, shock ripples, and nonstationarity. 

Experimental studies of ion dynamics at supercritical high Mach (>5) number shocks are typically conducted using planetary bow shock crossings since the Mach number of these shocks are higher while the shock speeds with respect to the observing spacecraft are lower. As a result, it is easier to resolve complex features in the ion velocity distribution function. For these reasons, studies concentrating on ion reflection at IP shocks are rare. However, comparisons with IP shocks are interesting since they have a much larger curvature radius and can be accompanied by more energetic particles.

In this work, we analyze a quasi-perpendicular shock observed by Solar Orbiter (SolO) on 30 October 2021 with a Mach number of around 7; this is much higher than the typical values of SolO IP shocks, which are between 1-3. For this event, we observed clear signatures in the upstream ion distribution function of reflected ions with energies extending to around 15 keV, which is lower than reported by other studies. The shock also demonstrates a non-planar feature, which may indicate shock rippling. In addition, whistler precursors are also found immediately upstream locally within the shock foot. We present these experimental results and a comparison with test-particle analysis and numerical modeling results.

How to cite: Dimmock, A., Gedalin, M., Trotta, D., Lalti, A., Graham, D., Khotyaintsev, Y., Vainio, R., Blanco-Cano, X., Kajdič, P., and Owen, C.: Ion reflection observed at high Mach number interplanetary shocks: Solar Orbiter observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11192, https://doi.org/10.5194/egusphere-egu23-11192, 2023.

Turbulence in plasmas involves a complex cross-scale coupling of fields and distortions of particle velocity distributions, with the generation of non-thermal features. How the energy contained in the large-scale fluctuations cascades all the way down to the kinetic scales, and how such turbulence interacts with particles, remains one of the major unsolved problems in plasma physics. Moreover, solar wind turbulence is not homogeneous but is highly space-localized and the degree of non-homogeneity increases as the spatial/time scales decrease (intermittency). Such an intermittent nature has also been found to evolve with distance from the Sun, possible due to the emergence of strong non-homogeneities over a broad range of scales.

Here, by means of new measurements by both Solar Orbiter and Parker Solar Probe, the radial evolution of a homogeneous recurrent fast wind, coming from the same source on the Sun (namely a coronal hole), has been studied from global properties and large-scale features to kinetic structures as it expands in the inner heliosphere from 0.1 out to 1 AU [Perrone et al., 2022]. In particular, the nature of the turbulent magnetic fluctuations around ion scales during the expansion of the wind, has been investigated and the observed coherent events both close to the Sun and to the Earth are statistically studied. The ion scales appear to be characterized by the presence of non-compressive coherent structures, such as current sheets, vortex-like structures, and wave packets identified as ion cyclotron modes, responsible for solar wind intermittency and strongly related to the energy dissipation. Particle energization, temperature anisotropy, and strong deviation from Maxwellian, have been observed in and near coherent structures, both in in-situ data and numerical simulations. Understanding the physical mechanisms that produce coherent structures and how they contribute to dissipation in collisionless plasma will provide key insights into the general problem of solar wind heating.

 

Perrone, D., et al. (2022) Astronomy & Astrophysics (Special Issue: Solar Orbiter First Results – Nominal Mission Phase) 668, A189

How to cite: Perrone, D.: Turbulence evolution of coronal hole solar wind in the inner heliosphere: Solar Orbiter and Parker Solar Probe combined observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11253, https://doi.org/10.5194/egusphere-egu23-11253, 2023.

EGU23-11714 | ECS | Orals | ST1.1

The role of electrons and helium atoms in global modeling of the heliosphere 

Federico Fraternale, Nikolai V. Pogorelov, and Ratan K. Bera

In situ and remote observations of the outer regions of the heliosphere and in the local interstellar medium (LISM) by Voyager, New Horizons, and IBEX continue to present new challenging questions, reflecting the complex processes of the solar wind (SW) - local interstellar medium (LISM) interaction. We present a new version of our recent 3-D MHD-plasma/kinetic-neutrals model of the SW-LISM interaction, which self-consistently includes neutral hydrogen and helium atoms. The new model treats electrons as a separate fluid assumed to co-move with the plasma mixture. In addition, it includes the effect of Coulomb collisions between electrons, He+ ions, and protons. The properties of electrons in the distant SW and in the very local interstellar medium (VLISM) are mostly unknown due to the lack of in situ observations. In this study we discuss the implications of using different models for the electron pressure. A common assumption (model 0) in single-ion global models is to assume that electrons have the pressure of the ion mixture. In this case electrons become hot in the distant SW where plasma is energetically dominated by pickup ions. In the proposed new model, electrons in the SW are colder, which leads to a better agreement with New Horizons observations in the supersonic SW. In the VLISM, however, ions and electrons may be almost in thermal equilibrium due to Coulomb collisions. As far as the plasma mixture properties are concerned, the major differences between the models are in the inner heliosheath, where colder electrons result in hotter protons and induce cooling of the plasma mixture due to the increase in the charge exchange frequency. This makes the heliosheath thinner by ~5 AU along the upstream direction and up to 60 AU in the downwind region. The filtration of interstellar H and He atoms is also discussed. At 1 AU, in the model with separate electrons the H density increases by ~2%. However, the fraction of pristine H atoms decreases by ~12%, while that of atoms born in the IHS increases up to ~35%. While the density of He atoms in the SW remains essentially unchanged, the contribution from the warm breeze increases by ~3%.

How to cite: Fraternale, F., Pogorelov, N. V., and Bera, R. K.: The role of electrons and helium atoms in global modeling of the heliosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11714, https://doi.org/10.5194/egusphere-egu23-11714, 2023.

The solar wind is an uninterrupted flow of highly ionised plasma that streams from compact sources at or near the Sun, accelerates across the low solar corona, and expands into the whole interplanetary space. The physical properties of any wind streams thus reflect the characteristics of their source regions and those of the extended zones of the corona they cross, and are affected by the time-varying strength and geometry of the global background magnetic field.  The rotational state of the solar corona also plays a fundamental role in a wide range of solar wind phenomena, but is much less well-known than that of the photosphere. In addition, surface dynamics and magnetic field evolution drive perturbations to the corona and wind that can either be transient or long-lasting.
We investigate the geometry and spatial distribution of solar wind sources by means of an extended time series of data-driven 3D simulations that cover nearly 2 activity cycles. We furthermore examine the corresponding solar wind acceleration profiles (radial trends) 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 (especially as the latter moves away from the ecliptic plane). We also highlight 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 point out directions to assess the effects of surface transient phenomena driven by flux emergence on the properties of the solar wind.

 

How to cite: Pinto, R., Rouillard, A., and Finley, A.: Steady and transient solar wind sources, acceleration profiles and rotation across the solar activity cycle, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12000, https://doi.org/10.5194/egusphere-egu23-12000, 2023.

EGU23-12727 | Posters on site | ST1.1

Candidates for downstream jets at interplanetary shocks 

Heli Hietala, Domenico Trotta, Lynn Wilson III, Annamaria Fedeli, and Laura Vuorinen

Localized 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 Earth.

In this study, we search for similar dynamic pressure pulses downstream of interplanetary shocks observed by the Wind spacecraft. We discuss how the jet selection criteria are adapted for such conditions. The interplanetary shocks where we have found jet candidates feature foreshock activity, a favourable condition for jet formation according to bow shock studies. We examine the properties of the candidate jets and compare them to those reported for magnetosheath jets. Widening the range of environments where downstream jets are observed can shed light on their dynamics and formation mechanisms.

How to cite: Hietala, H., Trotta, D., Wilson III, L., Fedeli, A., and Vuorinen, L.: Candidates for downstream jets at interplanetary shocks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12727, https://doi.org/10.5194/egusphere-egu23-12727, 2023.

EGU23-13848 | ECS | Orals | ST1.1

Frequency Distribution of Solar Oscillation Inside The Coronal Hole 

Aneta Wisniewska

Coronal holes are characterized by open magnetic field lines morphology. The strongest solar wind originates exactly from the area of solar coronal holes. From the other hand the solar oscillation is present at every point of the solar surface. Currently the mechanism which is responsible for formation of open coronal regions is still unidentified. We present a novel study of waves propagation and frequency distribution in coronal holes, which can bring a new insights in its origin. We investigate the discrepancies in the in waves propagation inside the coronal hole are and in its surrounding, using multi-channel intensity observations data from Atmospheric Imaging Assembly (AIA) and Dopplergrams from Helioseismic and Magnetic Imager (HMI) on board Solar Dynamics Observatory (SDO) at the level of photosphere, chromosphere and corona. We study power distribution of p-modes (5-minute oscillation) and wave frequencies above the acoustic cut-off frequency ѵ=5.3 mHz, for very fast waves, in the various levels of solar atmosphere, through helioseismic approach of wavelet 2D-spatial maps of the power spectral density estimated for the coronal hole area.

How to cite: Wisniewska, A.: Frequency Distribution of Solar Oscillation Inside The Coronal Hole, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13848, https://doi.org/10.5194/egusphere-egu23-13848, 2023.

EGU23-14753 | ECS | Posters on site | ST1.1

The effect of the morphology of coronal holes on the propagational evolution of high-speed solar wind streams in the inner heliosphere 

Stefan Hofmeister, Eleanna Asvestari, Jingnan Guo, Verena Heidrich-Meisner, Stephan Heinemann, Jasmina Magdalenic, Stefaan Poedts, Evangelia Samara, Manuela Temmer, Susanne Vennerstrom, Astrid Veronig, Bojan Vrsnak, and Robert Wimmer-Schweingruber

Since the 1970s it has been empirically known that the area of solar coronal holes a ects the properties of high-speed solar wind
streams (HSSs) at Earth. We derive a simple analytical model for the propagation of HSSs from the Sun to Earth and thereby show
how the area of coronal holes and the size of their boundary regions a ect the HSS velocity, temperature, and density near Earth.
We assume that velocity, temperature, and density profiles form across the HSS cross section close to the Sun and that these spatial
profiles translate into corresponding temporal profiles in a given radial direction due to the solar rotation. These temporal distributions
drive the stream interface to the preceding slow solar wind plasma and disperse with distance from the Sun. The HSS properties at
1AU are then given by all HSS plasma parcels launched from the Sun that did not run into the stream interface at Earth distance.
We show that the velocity plateau region of HSSs as seen at 1AU, if apparent, originates from the center region of the HSS close
to the Sun, whereas the velocity tail at 1AU originates from the trailing boundary region. Small HSSs can be described to entirely
consist of boundary region plasma, which intrinsically results in smaller peak velocities. The peak velocity of HSSs at Earth further
depends on the longitudinal width of the HSS close to the Sun. The shorter the longitudinal width of an HSS close to the Sun, the
more of its “fastest” HSS plasma parcels from the HSS core and trailing boundary region have impinged upon the stream interface
with the preceding slow solar wind, and the smaller is the peak velocity of the HSS at Earth. As the longitudinal width is statistically
correlated to the area of coronal holes, this also explains the well-known empirical relationship between coronal hole areas and HSS
peak velocities. Further, the temperature and density of HSS plasma parcels at Earth depend on their radial expansion from the Sun
to Earth. The radial expansion is determined by the velocity gradient across the HSS boundary region close to the Sun and gives the
velocity-temperature and density-temperature relationships at Earth their specific shape. When considering a large number of HSSs,
the assumed correlation between the HSS velocities and temperatures close to the Sun degrades only slightly up to 1AU, but the
correlation between the velocities and densities is strongly disrupted up to 1AU due to the radial expansion. Finally, we show how
the number of particles of the piled-up slow solar wind in the stream interaction region depends on the velocities and densities of the
HSS and preceding slow solar wind plasma.

How to cite: Hofmeister, S., Asvestari, E., Guo, J., Heidrich-Meisner, V., Heinemann, S., Magdalenic, J., Poedts, S., Samara, E., Temmer, M., Vennerstrom, S., Veronig, A., Vrsnak, B., and Wimmer-Schweingruber, R.: The effect of the morphology of coronal holes on the propagational evolution of high-speed solar wind streams in the inner heliosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14753, https://doi.org/10.5194/egusphere-egu23-14753, 2023.

EGU23-15303 | Posters on site | ST1.1

Kinetic models of asymmetric solar wind current sheets 

Thomas Neukirch, Ivan Vasko, Anton Artemyev, and Oliver Allanson

Current sheets in the collisionless solar wind usually have kinetic spatial scales. In-situ measurements show that these current sheets are often approximately force-free, i.e. the directions of their current density and magnetic field are aligned, despite the fact that the plasma beta is found to be of the order of one. The measurements also often show systematic asymmetric spatial variations of the plasma density and temperature across the current sheets, whilst the plasma pressure is approximately uniform. Neukirch et al. (2020) found exact equilibrium models of force-free collisionless current sheets which allowed for asymmetric plasma density and temperature gradients. These models assumed that the form of the distribution function for electrons and ions is the same. If one assumes that the bulk velocity of the ion population vanishes, the force-free condition is only satisfied approximately. Also, quasi-neutrality requires the presence of a nonvanishing electric potential. We show that an approximate treatment implies that the asymmetries in the density and the temperature only differ by a scale factor from the asymmetries found for the exactly force-free case.

T. Neukirch, I. Vasko, A. Artemyev and O. Allanson, ApJ 891, 86 (2020).

How to cite: Neukirch, T., Vasko, I., Artemyev, A., and Allanson, O.: Kinetic models of asymmetric solar wind current sheets, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15303, https://doi.org/10.5194/egusphere-egu23-15303, 2023.

EGU23-15872 | Posters on site | ST1.1

Statistical Study of Shock Rippling 

Yuri Khotyaintsev, Ajay Lotekar, Andreas Johlander, Daniel Graham, and Ahmad Lalti

MMS can resolve the fine structure of the shock ramp, which often shows holes in reduced ion-phase space distributions (integrated along the tangential plane of the shock). This is possible due to the high temporal resolutions of FPI/DIS. Such holes have been associated with ripples propagating along the shock surface but also can be related to the shock reformation. We statistically characterize the ion phase-space holes at the Earth’s bow shock using MMS observations. We establish a systematic procedure to find the shocks exhibiting the phase-space holes. We apply the procedure to ~500 shock crossings for which the burst data necessary to identify the holes is available. We identify phase-space holes for 66% of the crossings. We note that the actual occurrence is likely higher, as the holes are not resolved for fast shock crossings. We characterize the occurrence of the holes as a function of shock parameters such as Mach number and geometry. We find that the holes are widespread at the bow shock and are present for a wide range of shock geometries and Mach numbers (MA) studied. Their occurrence has no dependence on the shock geometry and increases with the Mach number, MA. The highest occurrence (70% probability) is for MA above 5. These results are essential to understanding the non-stationary behavior of collisionless shocks.

How to cite: Khotyaintsev, Y., Lotekar, A., Johlander, A., Graham, D., and Lalti, A.: Statistical Study of Shock Rippling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15872, https://doi.org/10.5194/egusphere-egu23-15872, 2023.

EGU23-16533 | ECS | Posters on site | ST1.1

Mathematical Morphology applied to solar features detection 

Slava Bourgeois, Andreas Wagner, Teresa Barata, Robertus Erdélyi, and Orlando Oliveira

Mathematical Morphology (MM) is an effective method to identify different types of features visible on the solar surface such as sunspots, facular regions, and pre-eruptive configurations of Coronal Mass Ejections (CMEs), which are important indicators of the Sun’s activity cycle.  On the one hand, we determine sunspots areas in Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) intensity images with this MM method, and we compare the obtained values with existing solar databases (e.g., the Debrecen Heliophysical Observatory catalogue or Mandal et al.'s catalogue [2020, A&A doi:10.1051/0004-6361/202037547]). The good agreement between the MM results and the existing catalogues validates the method, which we then apply to contour the different magnetic polarities in the SDO/Helioseismic and Magnetic Imager (HMI) magnetograms in order to identify so-called delta-sunspots. The next step is to investigate the correlation between solar flares and the length of these delta-sunspots contours. On the other hand, as another application, MM also helps us to extract flux rope structures from magnetic field models, using twist number maps obtained from a time-dependent magnetofrictional code. We can then investigate the evolution of the magnetic flux rope properties and the underlying triggers for the instability that ultimately leads to an eruption.

How to cite: Bourgeois, S., Wagner, A., Barata, T., Erdélyi, R., and Oliveira, O.: Mathematical Morphology applied to solar features detection, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16533, https://doi.org/10.5194/egusphere-egu23-16533, 2023.

EGU23-16814 | Orals | ST1.1

Solar Activities Associated with 3He-rich Solar Energetic Particle Events Observed by Solar Orbiter 

Nariaki Nitta, Radoslav Bucik, Glenn Mason, George Ho, Christina Cohen, Raul Gomez-Herrero, Linghua Wang, and Laura Balmaceda

Impulsive solar energetic particle (SEP) events are distinguished from shock-accelerated gradual SEP events especially in terms of their abundance enriched in 3He and heavy ions. Historically, 3He-rich  have been known to be accompanied by type III radio bursts and energetic electrons. For more than 15 years in the past it has often been proclaimed that coronal jets are responsible for 3He-rich SEP events. We revisit the link of 3He-rich SEP events with coronal jets in a series of 3He-rich SEP events that was observed by Solar Orbiter in May 2021 at a radial distance of 0.95 AU. An isolated active region AR 12824 was likely the ultimate source of these SEP events.  The period of the enhanced flux of 3He was also a period of frequent type III bursts in the  decametric-hectometric range, confirming their close relationship. As in past studies, we try to find the solar activities possibly responsible for 3He-rich SEP events, using the type III bursts close to the particle injection times estimated from the velocity dispersion. But this exercise is not as straightforward as in many of the past studies since the region produced many more type III bursts and jet-like eruptions than the SEP injections.  We may generalize the solar activities for the 3He-rich SEP events in question as coronal jets, but their appearances do not necessarily conform to classic jets that consist of a footpoint and a spire. Conversely, such jets often did not accompany type III bursts. The areas that produced jet-like eruptions changed within the active region from the first to the second set of 3He-rich SEP events, which may be related to the extended coronal mass ejection that launched stealthily, involving both the leading and trailing polarity areas of AR 12824.

How to cite: Nitta, N., Bucik, R., Mason, G., Ho, G., Cohen, C., Gomez-Herrero, R., Wang, L., and Balmaceda, L.: Solar Activities Associated with 3He-rich Solar Energetic Particle Events Observed by Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16814, https://doi.org/10.5194/egusphere-egu23-16814, 2023.

As the coronal dynamics is dominated by magnetic forces, the reconstruction of the coronal magnetic field is of major importance when studying the solar corona. Since coronal field measurements are not routinely available, photospheric fields are extrapolated into the corona in order to obtain the 3D coronal magnetic field structure. A nonlinear force-free field approximation is justified because of the low plasma  $\beta$. Previous extrapolation codes excluded high and low latitudes, because of the well know grid convergence problems at the poles. To overcome these limitations, we developed a new code implemented on a Yin-Yang grid, which was tested and verified with the Low and Lou solution as reference. Here we apply our code to synoptic vector magnetograms obtained from SDO/HMI during solar activity maximum and minimum, respectively. We compare our magnetic field models with EUV-observations of the solar corona as a first validation step.

How to cite: Koumtzis, A., Wiegelmann, T., and Madjarska, M.: Computing the global coronal magnetic field during activity maximum and minimum with a newly developed nonlinear force-free Yin-Yang code, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17168, https://doi.org/10.5194/egusphere-egu23-17168, 2023.

EGU23-1386 | Posters on site | ST1.2

Study of the evolution of interplanetary coronal mass ejections in the inner heliosphere 

Carlos Larrodera and Manuela Temmer

The launch of new spacecraft such as Parker Solar Probe or Solar Orbiter allow us to measure in-situ at different radial distances the physical magnitudes of ICMEs. With that, we are able to quantify the evolution of ICMEs and their substructures at a specific radial distance in order to better understand the interaction processes that occur with the background solar wind.
Using multiple spacecraft covering the inner heliosphere, we extract plasma and magnetic field parameters from several ICMEs to relate the physical processes responsible for the formation of the different substructures. We present ICME case studies that prepare for a large statistical analysis.

How to cite: Larrodera, C. and Temmer, M.: Study of the evolution of interplanetary coronal mass ejections in the inner heliosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1386, https://doi.org/10.5194/egusphere-egu23-1386, 2023.

Magnetic switchbacks are rapid high amplitude reversals of the radial
magnetic field in the solar wind that do not involve a heliospheric
current sheet crossing. First seen sporadically in the seventies in
Mariner and Helios data, switchbacks were later observed by the
Ulysses spacecraft beyond 1 au and have been recently identified as a
typical component of solar wind fluctuations in the inner heliosphere
by the Parker Solar Probe spacecraft. We provide a simple yet
predictive theory for the formation of these magnetic reversals: the
switchbacks are produced by the shear of circularly polarized Alfven
waves by a transversely varying radial wave propagation velocity.  The
wave speed can be modulated by variations in bulk velocity, radial
magnetic field, density or any combination of these.  We provide an
analytic expression for the magnetic field variation as a function of
the wave velocity shear, establish the necessary and sufficient
conditions for the formation of switchbacks and show that the
mechanism works in a realistic solar wind scenario. The suggested
mechanism is in full agreement with Parker Solar Probe observations,
including the shape of the switchbacks, the correlations of the
components of the magnetic field, and the dependence of various
quantities on radial distance.  We show conclusively that this is the
fundamental process that creates switchbacks.

How to cite: Toth, G.: A Simple yet Correct Theory for the Formation of Magnetic Switchbacks Observed by Parker Solar Probe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2914, https://doi.org/10.5194/egusphere-egu23-2914, 2023.

EGU23-3494 | Orals | ST1.2

Suprathermal Ion Observations Associated with the Heliospheric Current Sheet Crossings by Parker Solar Probe During Encounters 7-11 

Mihir Desai and the Parker Solar Probe ISOIS, SWEAP, and FIELDS Science Teams

We report observations of <100 keV/nucleon suprathermal (ST) H, He, O, and Fe ions in association with three separate crossings of the heliospheric current sheet that occurred near perhelia during PSP encounters 7-11. In particular, we compare and contrast the ST ion time-intensity profiles, velocity dispersion, pitch-angle distributions, spectral forms, and maximum energies during the three HCS crossings. We find that these unique ST observations are remarkably different in each case, with those during E07 posing the most serious challenges for existing models of ST ion production in the inner heliosphere. In contrast, the ISOIS observations during 4 separate HCS crossings during E08-11 appear to be consistent with a scenario in which ST ions escape out of the reconnection exhausts into the separatrix layers after getting accelerated up to ~50-100 keV/nucleon by HCS-associated magnetic reconnection-driven processes. We discuss these new observations in terms of local versus remote acceleration sources as well as in terms of expectations of existing ST ion production and propagation, including reconnection-driven and diffusive acceleration in the inner heliosphere.

How to cite: Desai, M. and the Parker Solar Probe ISOIS, SWEAP, and FIELDS Science Teams: Suprathermal Ion Observations Associated with the Heliospheric Current Sheet Crossings by Parker Solar Probe During Encounters 7-11, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3494, https://doi.org/10.5194/egusphere-egu23-3494, 2023.

EGU23-3671 | ECS | Orals | ST1.2

Magnetic Switchbacks Heat the Solar Corona 

Mojtaba Akhavan-Tafti, Justin Kasper, Jia Huang, and Luke Thomas

Magnetic switchbacks are short magnetic field reversals ubiquitously observed in the solar wind. The origin of switchbacks remains an important open science question, because of switchbacks’ possible role in the heating and acceleration of the solar wind. Here, we report observations of 501 robust switchbacks, using magnetic and plasma measurements from the first eight encounters by the Parker Solar Probe (PSP). More than 46% (6%) of switchbacks are rotational (tangential; TD) discontinuities (RD), defined as magnetic discontinuities with large (small) relative normal components of magnetic field and proton velocity. Magnetic reconnection in the solar atmosphere can be a source of the observed RD-type switchbacks. It is discovered that: 1) the RD-to-TD ratio exponentially decays with increasing heliocentric distance at rate 0.06 [RS-1], and 2) TD-type switchbacks contain 64% less magnetic energy than RD-type switchbacks, suggesting that RD-type switchbacks may relax into TD-type switchbacks. It is estimated that relaxing switchbacks generated via magnetic reconnection in the solar atmosphere can transfer an additional 16% of the total reconnected magnetic energy into heating and/or accelerating the solar corona, within 11.6 [RS] of the reconnection site. The roles of turbulence and/or waves in dissipating this energy into heating and/or accelerating the solar corona plasma are the remaining open science questions.

How to cite: Akhavan-Tafti, M., Kasper, J., Huang, J., and Thomas, L.: Magnetic Switchbacks Heat the Solar Corona, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3671, https://doi.org/10.5194/egusphere-egu23-3671, 2023.

There are few possibilities to put the in-situ measurements of the coronal electron density such as obtained by the Parker Solar Probe (PSP) in the context of the 3D configuration of the corona and its structure. One of them consists in using MHD models relying on synoptic maps of the photospheric magnetic field, but their accuracy is subject to questions, especially in the case of complex coronae of the maximum type. The 2D inversion of white-light coronagraphic images requires the simplified assumption of spherical symmetry of the corona which basically washes out the longitudinal variations. We will present preliminary results of a new method which makes use of the 3D time-dependent tomographic reconstruction of the coronal electron density based on accurately corrected and calibrated LASCO-C2 images of the polarized brightness of the corona. It is performed over a sliding window of 14 days (half a Carrington rotation) centered at the times of the PSP perihelion with a time interval of 4 days. The resulting “cubes” of the 3D electron density Ne are visualized from six different vantage points and with movies. The orbit of PSP is projected on a synoptic map of Ne extracted from the cubes at a heliocentric distance of 5.5 Rs; the track extends from Perihelion-5 days to Perihelion+5 days. The electron density at the heliocentric distances of PSP is extrapolated radially from the values at 5.5 Rs using an inverse square law and compared with the in-situ measurements collected by PSP/FIELDS. We will present results from the first PSP encounters.

How to cite: Lamy, P. and Wojak, J.: Connecting Coronal 3D Electron Density from Tomographic Reconstruction to In-situ Measurements from Parker Solar Probe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4352, https://doi.org/10.5194/egusphere-egu23-4352, 2023.

EGU23-4437 | Orals | ST1.2

Coronal Mass Ejection driven sheath regions and proton acceleration 

Emilia Kilpua and the Emilia Kilpua

Coronal Mass Ejections (CMEs) are large-scale eruptions from the Sun that drive shocks and turbulent sheaths ahead of them. Parker Solar Probe, Solar Orbiter and BepiColombo have recently observed several shocks/sheaths closer to the Sun than the Earth’s orbit. These studies have revealed enhanced energetic proton fluxes from in-situ observations in interplanetary space also in the sheaths preceding slow CMEs. In this presentation we discuss the internal small-scales sheath structures (e.g., mini flux ropes) and embedded magnetic fluctuations as well as related energization mechanisms. The results suggest that the CME-driven sheaths can have an important role in the acceleration of energetic particles.

How to cite: Kilpua, E. and the Emilia Kilpua: Coronal Mass Ejection driven sheath regions and proton acceleration, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4437, https://doi.org/10.5194/egusphere-egu23-4437, 2023.

EGU23-4502 | ECS | Orals | ST1.2

Coronal Diagnostics of Solar Type-III Radio Bursts Using LOFAR and PSP Observations 

Mohamed Nedal, Kamen Kozarev, Peijin Zhang, and Pietro Zucca

Understanding the physical processes underlying solar radio bursts requires both high- and low-frequency observations, as well as imaging capabilities. In this study, we implement a fully automated approach to detect and characterize type III radio bursts, image their sources in the corona, and characterize the plasma environment where the bursts are triggered. We utilize data from the Low-Frequency Array (LOFAR) and the Parker Solar Probe (PSP) to investigate several type-III radio bursts that occurred on April 3, 2019. Through data pre-processing and combining the LOFAR and PSP dynamic spectra, we study the solar radio emissions between 2.6 kHz and 80 MHz. By extracting the frequency drift and speed of the accelerated electron beams, we gain insight into the physical processes driving these bursts. Additionally, by using LOFAR interferometric observations to image the sources of the radio emission at multiple frequencies, we are able to determine the locations and kinematics of the sources in the corona. We also use Potential Field Source Surface (PFSS) modeling and magnetohydrodynamic (MHD) simulation results to determine the magnetic field configuration and plasma parameters in the vicinity of the moving emission sources. These observations and analysis provide valuable constraints on the coronal conditions that trigger solar radio bursts.

How to cite: Nedal, M., Kozarev, K., Zhang, P., and Zucca, P.: Coronal Diagnostics of Solar Type-III Radio Bursts Using LOFAR and PSP Observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4502, https://doi.org/10.5194/egusphere-egu23-4502, 2023.

EGU23-5698 | ECS | Posters on site | ST1.2

Substructures of coronal mass ejections (CMEs) and their solar source region 

Greta Cappello, Manuela Temmer, and Astrid Veronig

Parker Solar Probe (PSP) and Solar Orbiter (SolO) observe the Sun from unprecedented close-in orbits out of the Sun-Earth line. In combination with EUV imagery from STEREO and SDO, these unique and high-resolution data from different vantage points will give us new insights into the early evolution of coronal mass ejections (CMEs) in the low corona and inner heliosphere. For a case study, we apply 3D CME reconstruction methods to relate different CME substructures as observed in white-light coronagraphs like WISPR aboard PSP, to EUV off-limb structures for an erupting event. We interpret the results in terms of projection and Thomson scattering effects.

How to cite: Cappello, G., Temmer, M., and Veronig, A.: Substructures of coronal mass ejections (CMEs) and their solar source region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5698, https://doi.org/10.5194/egusphere-egu23-5698, 2023.

EGU23-7326 | ECS | Posters on site | ST1.2

Analysis of type III radio emissions observed by the Solar Orbiter spacecraft close to their source locations 

Tomáš Formánek, David Píša, Jan Souček, Ondřej Santolík, Antonio Vecchio, Milan Maksimovic, Javier Rodríguez-Pacheco, Timothy Horbury, and Christopher John Owen

Type III radio emissions are often observed by the Solar Orbiter spacecraft in the solar wind. They arise from a mode conversion of Langmuir waves generated by electron beams ejected from the Sun. In this study, we analyze sources of type III radio emissions that occurred after July 2020. We use data from the Radio and plasma waves (RPW), Energetic particle detector (EPD), Magnetometer (MAG), and Solar Wind Analyzer (SWA) instruments. We identify in-situ type III events and examine various parameters that may have influenced their generation mechanism. We use the maximum amplitude (MAMP) data product from the Time Domain Sampler (TDS) receiver of the RPW instrument for continuous tracking of Langmuir wave packets. For in-situ type III events throughout the Solar Orbiter mission, we study the wave polarization of the locally generated Langmuir waves measured in the Y-Z plane of the spacecraft reference frame. Using data from the EPD instrument, we obtain electron beam velocities for several in-situ events. We show that the electron beam velocity for those events is higher than predicted by previous studies.

How to cite: Formánek, T., Píša, D., Souček, J., Santolík, O., Vecchio, A., Maksimovic, M., Rodríguez-Pacheco, J., Horbury, T., and Owen, C. J.: Analysis of type III radio emissions observed by the Solar Orbiter spacecraft close to their source locations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7326, https://doi.org/10.5194/egusphere-egu23-7326, 2023.

EGU23-7866 | ECS | Posters virtual | ST1.2

Wavelet determination of magnetohydrodynamic range power spectral exponents in solar wind turbulence seen by Parker Solar Probe 

Xueyi wang, Sandra Chapman, Richard Dendy, and Bogdan Hnat
The high Reynolds number solar wind flow provides a natural laboratory for the study of turbulence in-situ. Parker Solar Probe samples the solar wind between 0.2 AU to 1 AU, providing an opportunity to study how turbulence evolves in the expanding solar wind. We obtain the scaling exponents and
scale breaks of wavelet power spectra of magnetic field fluctuations sampled by PSP/FIELDS. We identified multiple, long-duration intervals of uniform
solar wind turbulence, selected to exclude coherent structures such as pressure pulses and current sheets, and in which the primary proton population
velocity varies by less than 20% of its mean value. All selected events span the spectral scales from the approximately 1/f range at low frequencies, through the magnetohydrodynamic (MHD) inertial range of turbulence and into the kinetic range, below the ion gyrofrequency. We estimate the power spectral density (PSD) using a Haar wavelet decomposition which provides accurate estimates of the exponents. There is a clear transition between Kolmogorov 5/3 and Iroshnikov-Kraichnan 3/2 scaling inwards of 0.5 0.6AU. In some cases, we find two ranges of scaling within the inertial range, with scaling exponents that can be discriminated within uncertainties in the wavelet PSD. These correspond to relatively small plasma beta. Since the PSD estimated scaling exponents are a central prediction of turbulence theories, these results provide new insights into our understanding of the evolution of turbulence in the solar wind.
 

 

How to cite: wang, X., Chapman, S., Dendy, R., and Hnat, B.: Wavelet determination of magnetohydrodynamic range power spectral exponents in solar wind turbulence seen by Parker Solar Probe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7866, https://doi.org/10.5194/egusphere-egu23-7866, 2023.

EGU23-8514 | ECS | Posters on site | ST1.2

Occurrence and evolution of switchbacks between 13.3 to 70 solar radii: PSP Observations 

Vamsee Krishna Jagarlamudi, Nour E Raouafi, Sofiane Bourouaine, Parisa Mostafavi, and Andrea Larosa

Since its launch, the Parker Solar Probe (PSP) mission revealed the presence of numerous fascinating phenomena occurring closer to the Sun, such as the presence of ubiquitous switchbacks (SBs). The SBs are large magnetic field deflections of the local magnetic field relative to a background field. We investigated the statistical properties of the SBs during the first ten encounters between 13.3 and 70 Solar Radii using data from the SWEAP and FIELDS suites onboard PSP . We find that the occurrence rate of small deflections with respect to the Parker spiral decreases with radial distance (R). In contrast, the occurrence rate of the large deflections (SBs) increases with R, as does the occurrence rate of SB patches. We also find that the occurrence of SBs correlates with the bulk velocity of the solar wind, i.e., the higher the solar wind velocity, the higher the SB occurrence. For slow wind, the SB occurrence rate shows a constantly increasing trend between 13.3 and 70 solar radii. However, for fast wind, the occurrence rate saturates beyond 35 solar radii. Sub-Alfvenic regions encountered during encounters 8-10 have not shown significant SBs. This analysis of the PSP data hints that some of the SBs are decaying and some are being created in-situ.

How to cite: Jagarlamudi, V. K., Raouafi, N. E., Bourouaine, S., Mostafavi, P., and Larosa, A.: Occurrence and evolution of switchbacks between 13.3 to 70 solar radii: PSP Observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8514, https://doi.org/10.5194/egusphere-egu23-8514, 2023.

EGU23-9578 | Orals | ST1.2

Observations by Parker Solar Probe of a 3He-rich Solar Energetic Particle Event at 14 RS 

Christina Cohen and the ISOIS/FIELDS/SWEAP/WISPR study team

Just after orbit 12 closest approach, on 2 June 2022 at a distance of 14 RS, the Integrated Science Investigation of the Sun (ISʘIS) observed a 3He-rich solar energetic particle (SEP) event.  The event was associated with an active region just over the east limb (as viewed from Earth), which erupted with an occulted C1.2 class x-ray flare and a coronal mass ejection (CME) traveling ~350 km/s.  PSP observed a type III radio burst associated with the flare, followed by a type III storm.  After the initial dispersive SEP event, ISʘIS observed a second enhancement of energetic particles contained within the associated CME as it passed over the spacecraft.  Comparisons of these two populations provide information regarding the acceleration of particles at the Sun as well as trapping or acceleration within the CME structure as different components of an individual solar event.

How to cite: Cohen, C. and the ISOIS/FIELDS/SWEAP/WISPR study team: Observations by Parker Solar Probe of a 3He-rich Solar Energetic Particle Event at 14 RS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9578, https://doi.org/10.5194/egusphere-egu23-9578, 2023.

EGU23-10112 | ECS | Orals | ST1.2

On the mesoscale structure of CMEs at Mercury's orbit: Parker Solar Probe and BepiColombo observations 

Erika Palmerio, Fernando Carcaboso, Leng Ying Khoo, Beatriz Sánchez-Cano, Teresa Nieves-Chinchilla, David Lario, Yeimy Rivera, Sanchita Pal, Michael L. Stevens, Tarik M. Salman, Andreas J. Weiss, Christina O. Lee, Phyllis L. Whittlesey, and Daniel Heyner

On 15 February 2022, an impressive filament eruption was observed off the solar eastern limb from three remote-sensing viewpoints, namely Earth, STEREO-A, and Solar Orbiter. Apart from representing the most-distant observed filament at extreme ultraviolet wavelengths—captured by Solar Orbiter's field of view extending to above 6 Rs—this event was also associated with the release of a fast (~2200 km/s) coronal mass ejection (CME) that was directed towards Parker Solar Probe and BepiColombo.

Parker Solar Probe and BepiColombo were separated by 3° in latitude, 4° in longitude, and 0.03 au in radial distance at the time of the CME-driven shock arrival at the two spacecraft. The relative proximity of the two probes to each other and to the Sun (~0.365 au) allows us to study the mesoscale structure of CMEs at Mercury's orbit for the first time. We analyse similarities and differences in the magnetic structure of the CME ejecta measured at the two locations, as well as other properties such as shock/sheath characteristics, pitch-angle distributions, and impact of the interaction between the ejecta and its surroundings. Finally, we contextualise our findings within the current discussions on the need to investigate solar transients via spacecraft constellations with small separations, which have been gaining significant attention during recent years.

How to cite: Palmerio, E., Carcaboso, F., Khoo, L. Y., Sánchez-Cano, B., Nieves-Chinchilla, T., Lario, D., Rivera, Y., Pal, S., Stevens, M. L., Salman, T. M., Weiss, A. J., Lee, C. O., Whittlesey, P. L., and Heyner, D.: On the mesoscale structure of CMEs at Mercury's orbit: Parker Solar Probe and BepiColombo observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10112, https://doi.org/10.5194/egusphere-egu23-10112, 2023.

EGU23-10158 | ECS | Posters on site | ST1.2

Context studies of Parker Solar Probe and Solar Orbiter flybys using synthetic in-situ and remote-sensing observations 

Judit Szente, Bartholomeus van der Holst, and Enrico Landi

We use the Space Weather Modeling Framework's Alfvén Wave Solar atmosphere Model to simualte the origin and evolution of solar wind plasma during multiple SO and PSP flybys.   Synthetic spectral and narrow band imaging, synthetic spectra and in-situ plasma data are used to study the heating and acceleration of the coronal plasma and solar wind in the inner heliosphere. We identify large scale structures the spacecrafts pass through: current sheet crossings, plasmas of different origins. When data is available we simultaneously simulate non-equilibrium ionization of minor heavy ions in the solar wind along the SO trajectory and study how the plasma charge states represent the different origins of solar wind and also how the out-of-equilibrium charge states change the synthetic remote sensing observations compared to using equilibrium assumptions. 

How to cite: Szente, J., van der Holst, B., and Landi, E.: Context studies of Parker Solar Probe and Solar Orbiter flybys using synthetic in-situ and remote-sensing observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10158, https://doi.org/10.5194/egusphere-egu23-10158, 2023.

EGU23-11319 | Posters virtual | ST1.2

The reason for the wide particle spread during the 17 April 2021 SEP event 

Nina Dresing, Laura Rodríguez-García, Immanuel Jebaraj, Alexander Warmuth, Samantha Wallace, Laura Balmaceda, Tatiana Podladchikova, Du Toit Strauss, Athanasios Kouloumvakos, Christian Palmroos, Vratislav Krupar, Jan Gieseler, Zigong Xu, Grant Mitchell, Christina Cohen, Georgia de Nolfo, Erika Palmerio, Fernando Carcaboso, Emilia Kilpua, and Beatriz Sanchez-Cano

The widespread SEP event of 17 April 2021 was observed by five longitudinally well-separated observers in the inner heliosphere covering distances to the Sun from 0.42 to 1 au: BepiColombo, Parker Solar Probe, Solar Orbiter, STEREO A, and close-to-Earth spacecraft. The event, which produced relativistic electrons and protons, was associated with a complex and long-lasting solar eruption involving a long-duration flare, a medium-fast Coronal Mass Ejection (CME), an EUV wave and a complex solar radio burst activity lasting for 40 minutes including type II bursts, marking the presence of a shock, as well as four distinct groups of type III bursts. Our comprehensive analysis of the multi-spacecraft in-situ and remote-sensing observations suggests different source regions for the electron and proton SEP event with a stronger shock contribution for the proton event and a more likely flare-related source of the electron event. We furthermore determine that the four distinct injection episodes, marked by the radio type III burst groups, cover a longitudinal range of about 110° and were a main ingredient for the wide SEP spread. We consider this a new scenario that must be taken into account as a potential contributor to widespread SEP events.

How to cite: Dresing, N., Rodríguez-García, L., Jebaraj, I., Warmuth, A., Wallace, S., Balmaceda, L., Podladchikova, T., Strauss, D. T., Kouloumvakos, A., Palmroos, C., Krupar, V., Gieseler, J., Xu, Z., Mitchell, G., Cohen, C., de Nolfo, G., Palmerio, E., Carcaboso, F., Kilpua, E., and Sanchez-Cano, B.: The reason for the wide particle spread during the 17 April 2021 SEP event, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11319, https://doi.org/10.5194/egusphere-egu23-11319, 2023.

EGU23-11900 | ECS | Posters on site | ST1.2

Magnetic field spectra of ICMEs observed by Parker Solar Probe and Solar Orbiter 

Simon Good, Oskari Rantala, Anna-Sofia Jylhä, Christopher Chen, and Emilia Kilpua

A statistical study of magnetic field power spectra in interplanetary coronal mass ejections (ICMEs) observed by Parker Solar Probe and Solar Orbiter has been performed. The ICMEs had characteristically low proton beta, with values well below unity in all cases. The spectral index was typically near –5/3 and radially invariant in the inertial range, similar to solar wind near the heliospheric current sheet, and steepened to values below –3 in the kinetic range. The break frequency between the inertial and kinetic ranges evolved approximately linearly with radial distance and was closer in scale to the proton inertial length than the proton gyroscale. Magnetic compressibility was invariant with radial distance, in contrast to the solar wind generally. Removal of the background flux rope field gives spectra with shallower slopes at low frequencies (i.e. large spatial scales) and reveals shorter correlation lengths in the magnetic field.

How to cite: Good, S., Rantala, O., Jylhä, A.-S., Chen, C., and Kilpua, E.: Magnetic field spectra of ICMEs observed by Parker Solar Probe and Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11900, https://doi.org/10.5194/egusphere-egu23-11900, 2023.

EGU23-12288 | ECS | Orals | ST1.2

The Evolution of Turbulence in the Inner Heliosphere: Insights from the February 2022 Radial Alignment between Parker Solar Probe and Solar Orbiter 

Julia E. Stawarz, Lloyd Woodham, Ronan Laker, Lorenzo Matteini, Timothy Horbury, Thomas Woolley, Stuart Bale, Denise Perrone, Sergio Toledo-Redondo, Luca Sorriso-Valvo, Raffaella D’Amicis, Yeimy Rivera, and Kristoff Paulson

The solar wind is filled with complex turbulent dynamics that transfer energy from large length scales to progressively smaller scales. This transfer of energy generates a multitude of thin structures, such as current sheets, in the plasma with a preference for forming particularly strong gradients – a property know as intermittency – that are thought to play a role in turbulent dissipation. One of the important problems in the study of solar wind turbulence is understanding how and to what extent the nature of the turbulent dynamics vary as the solar wind expands from the Sun. However, disentangling the dynamical evolution of the turbulence from variations in the properties of different solar wind streams and temporal variations in the source region of a given stream has traditionally been challenging in the solar wind. We make use of a fortuitous alignment between NASA’s Parker Solar Probe and ESA’s Solar Orbiter spacecraft, which occurred at the end of February 2022, to examine how the turbulent fluctuations in the solar wind evolve with radial distance. During this radial alignment the two spacecraft observed the same stream of solar wind plasma, and potentially nearly the same parcel of plasma, at two different radial distances allowing us to separate the evolution with radial distance from the other sources of variability. We explore both the statistical properties of the fluctuations as well as the nature of the most intermittent structures observed by the spacecraft at different length scales in the plasma. The results demonstrate that, while the intermittent fluctuations in the components perpendicular to the radial direction are statistically similar at different radial distances, the intermittency properties in the radial direction can significantly change with distance. Comparisons of the observational results with expanding box simulations of turbulence suggest that some of the key features observed are consistent with the dynamical evolution of spherically polarised Alfvénic fluctuations under the influence of expansion. 

How to cite: Stawarz, J. E., Woodham, L., Laker, R., Matteini, L., Horbury, T., Woolley, T., Bale, S., Perrone, D., Toledo-Redondo, S., Sorriso-Valvo, L., D’Amicis, R., Rivera, Y., and Paulson, K.: The Evolution of Turbulence in the Inner Heliosphere: Insights from the February 2022 Radial Alignment between Parker Solar Probe and Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12288, https://doi.org/10.5194/egusphere-egu23-12288, 2023.

EGU23-12976 | Orals | ST1.2

Near-Sun Alfvenic Slow Solar Wind with Variable Helium Abundance: PSP observation and source tracing 

Ziqi Wu, Jiansen He, Chuanpeng Hou, Jingyu Peng, and Die Duan

The solar wind, except for the coronal mass ejection events, is traditionally divided into two groups, fast wind and slow wind. However, the origin and releasing mechanism of highly variable slow winds are still a riddle. The slow wind is generally believed to have low Alfvénicity, while the fast wind shows high Alfvénicity. However, Parker Solar Probe shows that highly Alfvénic slow winds take a large proportion of the near-Sun pristine slow winds, suggesting similar sources with the Alfvénic fast winds. Helium abundance (Nα/Np) also bears information about the source region and release mechanism of the slow winds. The typical value of helium abundance in slow winds can be as low as 1% or even lower, while it stays around 4% in fast winds. During its 8th encounter, PSP observed intervals of helium-poor (Nα/Np~0.1%) and helium-normal (Nα/Np~1%) Alfvénic solar winds on two sides of the heliospheric current sheet. We calculate and compare the alpha-particle properties, plasma parameters, collisional age, and magnetic fluctuations in these intervals statistically. In addition, we check the magnetic connection from PSP to the Sun during these intervals with two-step ballistic backmapping. We conclude that the helium-poor winds originate from large quiescent magnetic loops and experience sufficient collisions before and during release. In contrast, helium-normal winds originate from low-latitude coronal holes and experience preferential acceleration and heating due to wave-particle interactions. These results suggest that Alfvénic slow solar winds likely have multiple origins.

How to cite: Wu, Z., He, J., Hou, C., Peng, J., and Duan, D.: Near-Sun Alfvenic Slow Solar Wind with Variable Helium Abundance: PSP observation and source tracing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12976, https://doi.org/10.5194/egusphere-egu23-12976, 2023.

EGU23-15607 | ECS | Posters on site | ST1.2

Density oscillations in the solar corona seen in radio occultation measurements  and a MHD simulation 

Shota Chiba, Takeshi Imamura, and Munehito Shoda

The solar wind is a supersonic plasma flow streamed from the solar corona. The acceleration of the solar wind mainly occurs in the outer corona at heliocentric distances of about 2­–10 RS (= solar radii), where the coronal heating by magnetohydrodynamic waves and the wave-induced magnetic pressure are thought to play major roles in the acceleration. The mechanisms have not been fully confirmed because the acceleration region is where no spacecrafts have ever reached to date. Recently, however, an inner heliosphere observation network is getting ready, by such as NASA’s Parker Solar Probe and ESA's Solar orbiter and BepiColombo.

Radio occultation observations cover the acceleration region fully and can obtain information complementary to in-situ observations. The radio occultation observations are conducted during the passage of a spacecraft on the opposite side of the sun as seen from the Earth. Inhomogeneity of coronal plasma density structure traversing the ray path disturbs radio waves' frequency, so we can interpret the received frequency fluctuations as density fluctuations in the coronal plasma. Previous observations detected quasi-periodic components thought to represent magnetoacoustic waves (e.g, Efimov et al., 2012; Miyamoto et al., 2014). The details of the detected waves still have not been investigated.

A recent MHD simulation have reproduced the formation of the solar wind based on the wave/turbulence-driven scenario, in which ubiquitous presence of density fluctuation is found. We applied the spectral analysis to the density fluctuations to compare them with the wave components observed by radio occultation observations conducted by JAXA’s Akatsuki spacecraft in 2016. The time-spatial spectrum of density fluctuations has two components whose phase speeds correspond to the Alfvén speed and sound speed, and these two components are considered to be fast and slow modes. The dominant periods of the slow modes in the model are longer than 100 s, which is consistent with the density fluctuations observed by the radio occultation. The periods of the fast modes in the model are about 20–100 s; such short-period components are also seen in the radio occultation observations. These different modes might have been observed by radio occultation simultaneously.

How to cite: Chiba, S., Imamura, T., and Shoda, M.: Density oscillations in the solar corona seen in radio occultation measurements  and a MHD simulation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15607, https://doi.org/10.5194/egusphere-egu23-15607, 2023.

EGU23-17376 | Orals | ST1.2 | Highlight

Magnetic Reconnection as the Driver of the Solar Wind 

Nour E. Raouafi, Guillermo Stenborg, Dan B. Seaton, Haimin Wang, Jason Wang, Craig E. DeForest, Stuart D. Bale, James F. Drake, Vadim M. Uritsky, Judith T. Karpen, Carl R. DeVore, Alphonse C. Sterling, Timothy S. Horbury, Louise K. Harra, Sofiane Bourouaine, Justin C. Kasper, Pankaj Kumar, Tai D. Phan, and Marco Velli

We present an overview of EUV solar observations showing evidence for ubiquitous small-scale jetting activity (i.e., a.k.a. jetlets) driven by magnetic reconnection that might be the primary driver of the solar wind at its source. The jetlets, like the solar wind and the heating of the coronal plasma, are omnipresent throughout the solar cycle. Each event arises from small-scale reconnection of opposite polarity magnetic fields producing a short-lived jet of hot plasma and Alfvén waves into the corona. The discrete nature of the jetlets leads to intermittent outflows from the corona, which homogenize as they propagate away from the Sun and form the solar wind. This discovery establishes the importance of small-scale magnetic reconnection in solar and stellar atmospheres in understanding ubiquitous phenomena such as coronal heating and solar wind acceleration. Based on previous analyses linking the switchbacks to the magnetic network, we also argue that these new observations might provide the link between the magnetic activity at the base of the corona and the switchback solar wind phenomenon. These new observations need to be put in the bigger picture of the role of magnetic reconnection and the diverse form of jetting in the solar atmosphere.

How to cite: Raouafi, N. E., Stenborg, G., Seaton, D. B., Wang, H., Wang, J., DeForest, C. E., Bale, S. D., Drake, J. F., Uritsky, V. M., Karpen, J. T., DeVore, C. R., Sterling, A. C., Horbury, T. S., Harra, L. K., Bourouaine, S., Kasper, J. C., Kumar, P., Phan, T. D., and Velli, M.: Magnetic Reconnection as the Driver of the Solar Wind, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17376, https://doi.org/10.5194/egusphere-egu23-17376, 2023.

EGU23-17541 | Orals | ST1.2

The interplay between Solar Wind Turbulence and magnetic Switchbacks in the inner Heliospere 

Andrea Larosa, Christopher H. K. Chen, Jack McIntyre, and Vamsee K. Jagarlamudi

One of the most intriguing discoveries of the Parker Solar Probe mission is the presence of magnetic field reversals, known as Switchbacks (SBs), in the near Sun environment. Their origins are still unclear and many mechanisms for their generations have been proposed. On top of that their interactions with the background solar wind turbulence is not yet understood. In this work we investigate whether the SBs can be considered as part of the background solar wind turbulence or as a population of separate structures. We address this problem by studying the distributions of different measures of the turbulence and SBs and their radial evolution. These results are valuable for the understanding of switchbacks formation and of how turbulence affects the generation of structures in the solar wind.  

How to cite: Larosa, A., Chen, C. H. K., McIntyre, J., and Jagarlamudi, V. K.: The interplay between Solar Wind Turbulence and magnetic Switchbacks in the inner Heliospere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17541, https://doi.org/10.5194/egusphere-egu23-17541, 2023.

EGU23-424 | ECS | Posters on site | ST1.3

Comparison of the Magnetic Field Inferred by SO/PHI-HRT and SDO/HMI 

Jonas Sinjan, Daniele Calchetti, Johann Hirzberger, Sami Khan Solanki, Jose Carlos del Toro Iniesta, Joachim Woch, Achim Gandorfer, Alberto Alvarez-Herrero, Thierry Appourchaux, Reiner Volkmer, and David Orozco Suárez

Onboard the Solar Orbiter spacecraft is the Polarimetric and Helioseismic Imager (SO/PHI), which has two telescopes, a high resolution telescope (HRT) and the full disk telescope (FDT). The instrument is designed to infer the photospheric magnetic field through differential imaging of the polarised light emitted from the Sun. It is the first magnetograph to move out of the Sun-Earth Line, providing excellent stereoscopic opportunities with other ground and space based instruments. Of particular interest is the comparison between SO/PHI-HRT and the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory (SDO/HMI). They probe the same magnetically sensitive line of Fe1: 6173 Å and have the same aperture diameter. In March 2022 Solar Orbiter crossed the Sun-Earth line, providing an excellent opportunity for a comparison. Here a comparison between the magnetic fields, both line-of-sight and all three vector components, inferred by SDO/HMI and SO/PHI-HRT during the conjunction, are presented. 

How to cite: Sinjan, J., Calchetti, D., Hirzberger, J., Solanki, S. K., del Toro Iniesta, J. C., Woch, J., Gandorfer, A., Alvarez-Herrero, A., Appourchaux, T., Volkmer, R., and Orozco Suárez, D.: Comparison of the Magnetic Field Inferred by SO/PHI-HRT and SDO/HMI, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-424, https://doi.org/10.5194/egusphere-egu23-424, 2023.

EGU23-447 | ECS | Posters on site | ST1.3 | Highlight

Magnetic Reconnection as a Dissipation Mechanism for Magnetic Switchbacks 

Gabriel Suen, Christopher Owen, Daniel Verscharen, Timothy Horbury, and Philippe Louarn

Context: Magnetic switchbacks are localised polarity reversals in the radial component of the heliospheric magnetic field. Observations from Parker Solar Probe (PSP) have shown that they are a prevalent feature of the near-Sun solar wind. However, observations of switchbacks at 1 au and beyond are less frequent, suggesting that these structures are dissipated by yet-to-be identified mechanisms as they propagate away from the Sun.

Aims: We estimate the timescales over which magnetic switchbacks may be dissipated by magnetic reconnection and evaluate the viability of reconnection as a dissipation mechanism for switchbacks.

Methods: We analyse magnetic field and plasma data from the magnetometer and Solar Wind Analyser instruments aboard Solar Orbiter between 10 August and 30 August 2021. During this period, the spacecraft was 0.6 – 0.7 au from the Sun.

Results: We identify three instances of reconnection occurring at the trailing edge of magnetic switchbacks. Using hodographs and Walen analysis methods, we find that the reconnection exhaust region for all three events are bound by rotational discontinuities in the magnetic field, consistent with existing models describing the properties of reconnection in the solar wind. Based on these observations, we propose a scenario through which reconnection can dissipate a switchback and we estimate the timescales over which this occurs. We find that for our events the dissipation timescales are much shorter than the expansion timescale and thus, the complete dissipation of all three observed switchbacks would occur well before they reach Earth. Furthermore, assuming the observed reconnection rate has remained constant, and extrapolating back to an origin close to the Sun, we find that the spatial scale of these switchbacks would be considerably larger than is typically seen in the inner heliosphere. Hence, it is implied that the onset of reconnection must occur during transport in the solar wind. If typical, these results suggest that reconnection can play a significant role in dissipating switchbacks and could help explain the relative rarity of switchback observations at 1 au.

How to cite: Suen, G., Owen, C., Verscharen, D., Horbury, T., and Louarn, P.: Magnetic Reconnection as a Dissipation Mechanism for Magnetic Switchbacks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-447, https://doi.org/10.5194/egusphere-egu23-447, 2023.

EGU23-2236 | ECS | Posters on site | ST1.3

Acceleration of Suprathermal protons near an Interplanetary Shock 

Liu Yang, Verena Heidrich-Meisner, Lars Berger, Robert Wimmer-Schweingruber, Linghua Wang, Jiansen He, Xingyu Zhu, Die Duan, Alexander Kollhoff, Daniel Pacheco, Patrick Kühl, Zigong Xu, Duncan Keilbach, Javier Rodríguez-Pacheco, and George Ho

Context. Interplanetary collisionless shocks are known to be sources of energetic charged particles up to hundreds of MeV. However, the underlying acceleration mechanisms are still under debate.
Aims. We determine the properties of suprathermal protons accelerated by the interplanetary shock on 2021 November 3 with the unprecedented high-resolution measurements by the SupraThermal Electron Proton sensor of the Energetic Particle Detector onboard the Solar Orbiter spacecraft, in order to constrain the potential shock acceleration mechanisms.
Methods. We first reconstruct the pitch-angle distributions (PADs) of suprathermal protons in the solar wind frame. Then, we study the evolution of the PADs, flux temporal profile and velocity distribution function of this proton population close to the shock and compare the observations to theoretical predictions.
Results. We find that the suprathermal proton fluxes peak 
12 to 24 seconds before the shock in the upstream region. The proton fluxes rapidly decrease by 50% in a thin layer (8000 km) adjacent to the shock in the downstream region and become constant further downstream. Furthermore, the proton velocity distribution functions in the upstream (downstream) region fit to a double power law, f (v)  v−γ, at 1000  3600 km s−1, with a γ of 3.4 ± 0.2 (4.3 ± 0.7) at velocities (v) below a break at 1800 ± 100 km s−1 (1600 ± 200 km s−1) and a γ of 5.8 ± 0.3 (5.8 ± 0.2) at velocities above. These indices are all smaller than predicted by first-order Fermi acceleration. In addition, the proton PADs show anisotropies in the direction away from the shock in the close upstream region and become nearly isotropic further upstream, while downstream of the shock, they show a clear tendency of anisotropies towards 90 PA.
Conclusions. These results suggest that the acceleration of suprathermal protons at interplanetary shocks are dynamic on a time scale of
10 seconds, i.e., few proton gyro-periods. Furthermore, shock drift acceleration likely plays an important role in accelerating these suprathermal protons.

How to cite: Yang, L., Heidrich-Meisner, V., Berger, L., Wimmer-Schweingruber, R., Wang, L., He, J., Zhu, X., Duan, D., Kollhoff, A., Pacheco, D., Kühl, P., Xu, Z., Keilbach, D., Rodríguez-Pacheco, J., and Ho, G.: Acceleration of Suprathermal protons near an Interplanetary Shock, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2236, https://doi.org/10.5194/egusphere-egu23-2236, 2023.

EGU23-2688 | Posters on site | ST1.3

The STIX imaging concept: model for data formation and image reconstruction methods for the Spectrometer/Telescope for Imaging X-rays on-board Solar Orbiter 

Michele Piana, Paolo Massa, Anna Volpara, Anna Maria Massone, Federico Benvenuto, Emma Perracchione, Andrea Francesco Battaglia, Gordon Hurford, and Sam Krucker

The Spectrometer/Telescope for Imaging X-rays (STIX) on-board Solar Orbiter measures the X-ray photons emitted by thermal and non-thermal electrons via bremsstrahlung mechanisms. STIX modulates the incident radiation by means of 30 sub-collimators that provide information on the complex values of specific Fourier components of the flaring X-ray source. This talk will illustrate this data formation process and explain how this model can be exploited to formulate image reconstruction methods including constrained maximum entropy, multi-scale CLEAN, feature augmentation, and Particle Swarm Optimization for parametric imaging. These methods will be applied against several experimental STIX observations and the reliability of the reconstructed morphologies will be validated by comparison with EUV maps recorded by the Atmospheric Imaging Assembly (AIA) on-board the Solar Dynamics Observatory.

How to cite: Piana, M., Massa, P., Volpara, A., Massone, A. M., Benvenuto, F., Perracchione, E., Battaglia, A. F., Hurford, G., and Krucker, S.: The STIX imaging concept: model for data formation and image reconstruction methods for the Spectrometer/Telescope for Imaging X-rays on-board Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2688, https://doi.org/10.5194/egusphere-egu23-2688, 2023.

EGU23-3094 | Orals | ST1.3 | Highlight

The source of unusual coronal upflows with photospheric abundance in a solar active region 

Louise Harra, Cristina Mandrini, and David Brooks and the Solar Orbiter EUI collaborators

Upflows in the corona are of importance as they may contribute to the solar wind. Because of this, there has been interest
in the analysis of upflows at the edges of active regions (ARs). The coronal upflows that are seen at the edges of ARs have coronal
elemental composition and can contribute to the slow solar wind. The sources of the upflows have been challenging to determine
because they may be multiple.

In this talk, we will discuss the latest results of coronal upflows. This includes an example which is found unusually close to a sunspot umbra and unusually has photospheric abundance. We analyse in detail the cause of this upflow region using a combination of Solar Orbiter EUV images at high spatial and temporal resolution,
Hinode/EUV Imaging Spectrometer data, and observations from instruments on board the Solar Dynamics Observatory. This com-
bined dataset was acquired during the first Solar Orbiter perihelion of the science phase, which provided a spatial resolution of 356
km for 2 pixels.  In the location of the, a small positive polarity connects to the umbra
via small-scale and very dynamic coronal loops.  The Solar Orbiter EUV Imagers (EUI) high resolution data show the dynamics of these small loops, which last on timescales of only minutes. This is the location of the coronal upflow which has photospheric abundance. We attempt to determine if it is possible that they can feed into the slow solar wind. We discuss future observation potential using Solar Orbiter data along with data from other missions and ground-based observatories. This provides opportunities for multiple viewpoints, multi-wavelength measurements of these upflow regions.

How to cite: Harra, L., Mandrini, C., and Brooks, D. and the Solar Orbiter EUI collaborators: The source of unusual coronal upflows with photospheric abundance in a solar active region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3094, https://doi.org/10.5194/egusphere-egu23-3094, 2023.

EGU23-3618 | ECS | Posters on site | ST1.3

Spatially resolved imaging spectroscopy with the Spectrometer/Telescope for Imaging X-rays on-board Solar Orbiter 

Anna Volpara, Paolo Massa, Anna Maria Massone, and Michele Piana

The fundamental science objective behind solar X-ray imaging spectroscopy is to gain information on the electrons accelerated by magnetic reconnection and on the temperature of the correspondingly heated plasma throughout the whole flaring volume. This talk will prove that the visibility-based technology at the base of the Spectrometer/Telescope for Imaging X-rays (STIX) allows the construction of electron flux and differential emission measure maps that are nicely smoothed along the energy and temperature directions, respectively. Using this approach, we will perform a spatially resolved analysis of the electron flux spectra associated with hard X-ray emissions measured by STIX and discuss the spatially resolved consistency of such emissions with a thermal distribution of the electrons in the flaring source.

How to cite: Volpara, A., Massa, P., Massone, A. M., and Piana, M.: Spatially resolved imaging spectroscopy with the Spectrometer/Telescope for Imaging X-rays on-board Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3618, https://doi.org/10.5194/egusphere-egu23-3618, 2023.

EGU23-4385 | Orals | ST1.3

April 3, 2022 in-situ ESP event as observed by Solar Orbiter, ACE and Stereo 

George Ho, Glenn Mason, Robert Allen, Athanasios Kouloumvakos, Robert Wimmer-Schweingruber, Javier Rodríguez-Pacheco, and Raúl Gómez-Herrero

The propagation and radial evolution of energetic particle events can only be studied by multiple-point simultaneous in-situ measurement within the heliosphere.  The joint ESA/NASA Solar Orbiter mission that was launched in February 2020, is designed to study the Sun and inner heliosphere in greater detail than ever before.  The Energetic Particle Detector (EPD) investigation on Solar Orbiter is a suite of four different sensors that measure the energetic particles from slightly above solar wind energies to hundreds of MeV/nucleon. Since launched, EPD already observed numerous large solar energetic particle (SEP) and energetic storm particle (ESP) events inside of 1 au in greater temporal and spectral resolutions than ever before.  Many of these events were also measured by spacecraft at 1 au such as ACE and/or STEREO. 

On April 2, 2022, an active region (AR 12975) on the western limb (W80) of the Sun produced a large SEP event and associated fast moving (>1400 km/s) coronal mass ejection (CME) and a CME-driven interplanetary shock (~1900 km/s).  During that time, the Solar Orbiter spacecraft was cruising near its perihelion distance (~0.35 au) at W109 relative to the Earth-Sun line, and the STEREO Ahead spacecraft was at E35.  Together, the particle instruments on these probes measured the SEP/ESP and the plasma and field instruments detected the associated interplanetary shock/CMEs on April 2-3, 2022.  In this paper, we report the multi-spacecraft observations of this event that were measured by Solar Orbiter, and we discuss the propagation and transport of SEPs from 0.3 to 1 au.

How to cite: Ho, G., Mason, G., Allen, R., Kouloumvakos, A., Wimmer-Schweingruber, R., Rodríguez-Pacheco, J., and Gómez-Herrero, R.: April 3, 2022 in-situ ESP event as observed by Solar Orbiter, ACE and Stereo, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4385, https://doi.org/10.5194/egusphere-egu23-4385, 2023.

EGU23-4615 | ECS | Posters virtual | ST1.3

Extended 3He-rich time periods observed by Solar Orbiter 

Athanasios Kouloumvakos, Glenn M. Mason, George C. Ho, Robert C. Allen, Alexis P. Rouillard, Javier R. Rodríguez-Pacheco, Robert F. Wimmer-Schweingruber, and Raúl Gómez-Herrero

Solar energetic particle (SEP) observations from Suprathermal Ion Spectrograph (SIS) which is part of the Energetic Particle Detector (EPD) suite on board the Solar Orbiter (SolO) mission, provide an unprecedented opportunity to study the composition and evolution of SEPs close at the Sun and to understand where SEPs are accelerated at the Sun and when released from their sources to interplanetary space. In this study, we examine 3He-rich time periods that last for many days. These extended 3He-rich periods that observed by SIS are particularly interesting because this rare isotope of He is not abundant in the solar corona and events rich of 3He are usually associated with transient and small "impulsive" SEP events. First, we compile a catalogue of extended 3He-rich time periods that were observed during the first three years of SolO mission and we determined and registered their characteristics (duration, composition, etc.). We also examined the spacecraft’s magnetic connectivity during these time periods and the characteristics of the connected regions. We find that, during the extended 3He-rich time periods, SolO is stably magnetically connected to an active region(s) for most cases. The connectivity usually changes near the boundaries of the time periods so the connectivity to the source region is an important element for the observation of these 3He-rich time periods. The active region(s) where SolO is magnetically connected during the time periods are typically very productive of solar events (flares, jets, CMEs). 

How to cite: Kouloumvakos, A., Mason, G. M., Ho, G. C., Allen, R. C., Rouillard, A. P., Rodríguez-Pacheco, J. R., Wimmer-Schweingruber, R. F., and Gómez-Herrero, R.: Extended 3He-rich time periods observed by Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4615, https://doi.org/10.5194/egusphere-egu23-4615, 2023.

EGU23-4805 | Orals | ST1.3

Thermal-nonthermal energy partition in weak flares observed by STIX, XSM, and SDO 

Arun Kumar Awasthi, Tomasz Mrozek, Michalina Litwicka, Marek Steslicki, Sylwester Kolomanski, and Karol Kulaga

The disparate nature of thermal-nonthermal energy partition during weak flares compared to that during the large flares is still an open issue and quantifying the relative productivity of multi-wavelength emission during weak flares can enable inferring the underlying energy release mechanism. Therefore, we analyze multi-wavelength emission from ∼150 flares during September 20-25, 2021, commonly observed from Spectrometer Telescope for Imaging X-rays (STIX) (at ∼0.6 AU), STEREO-A, GOES, and SDO observatories (significant overlap of observing field-of-view). The ratio (Qf ) of HXR (>12 keV) fluence (Fhxr ) and SXR (4-10 keV) flux (Fsxr), at the maximum of Fsxr (tp), is derived to quantify the relative productivity of HXR and SXR emission during flares. The variation of Qf with Fsxr enabled us to quantitatively identify the cases of strongly non-thermal (cold) and highly thermal (hot) flares. The identification of the source active region using the EUV images (from AIA) revealed the uniform behavior of different active regions in producing cold and hot flares. Besides, thermal-nonthermal plasma parameters as estimated by spectral-fit of STIX and XSM observations indicate a possible role of pre-flare density in flare loops to be resulting in disparate thermal-nonthermal emission partition. Therefore, we conduct case studies of flares of the aforementioned types by – synthesizing the X-ray images from STIX observations – analyzing the E/UV images, and magnetograms, and — performing the hydrodynamical simulations using the 1D Palermo-Harvard code. With such a multi-wavelength analysis of an ensemble of weak flares, we probe the energy release mechanism and evaluate the same in the framework of the standard model of energy release during large flares.

How to cite: Awasthi, A. K., Mrozek, T., Litwicka, M., Steslicki, M., Kolomanski, S., and Kulaga, K.: Thermal-nonthermal energy partition in weak flares observed by STIX, XSM, and SDO, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4805, https://doi.org/10.5194/egusphere-egu23-4805, 2023.

EGU23-5652 | Posters on site | ST1.3

Photoelectrons and spacecraft potential effects on SWA-EAS electron measurements on board the Solar Orbiter spacecraft 

Stepan Stverak, David Herčík, Petr Hellinger, Georgios Nicolaou, Christopher Owen, and Milan Maksimovic

Any spacecraft immersed into the solar wind builds up a non-zero electric potential with respect to the local environment by continuously collecting the charged particles from ambient plasma populations and emitting additional charged particle populations, namely photo-electrons and/or secondary electrons, from its surface materials. These newborn electrons of spacecraft origin as well as the electric fields induced in the vicinity of the spacecraft body by the so called spacecraft potential may in turn significantly distort the local plasma conditions and therefore affect any in-situ electron observations and thus potentially modify the derived electron properties. Here we present an observational analysis of these effects as seen by the SWA-EAS electron analyser in the variable plasma and electrostatic environment of the Solar Orbiter spacecraft. We provide some characteristic properties of these parasitic electron populations in order to later develop possible correction methods applied to the SWA-EAS measurements for deriving unperturbed ambient plasma properties. The analysis is performed on a statistical basis using a large set of SWA-EAS 3D electron velocity distribution functions and in comparison to other relevant in-situ measurements acquired namely by other two complementary on board plasma instruments – SWA-PAS and RPW.

How to cite: Stverak, S., Herčík, D., Hellinger, P., Nicolaou, G., Owen, C., and Maksimovic, M.: Photoelectrons and spacecraft potential effects on SWA-EAS electron measurements on board the Solar Orbiter spacecraft, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5652, https://doi.org/10.5194/egusphere-egu23-5652, 2023.

EGU23-6664 | ECS | Posters on site | ST1.3

Statistical study of the solar wind properties using the magnetic connectivity from in-situ measurements of Solar Orbiter extrapolated sunward the Solar Corona. 

Jean-Baptiste Dakeyo, Alexis Rouillard, Milan Maksimovic, Victor Réville, Philippe Louarn, and Pascal Démoulin

Using the magnetic field properties in the interplanetary medium and near the Sun allows to trace back the trajectory of an in-situ observed parcel of solar wind. This kind of study has already shown around 1 AU an anti-correlation between the speed of the wind, and both the expansion factor of the flux tube and the magnetic field magnitude of the source (Wang & Sheeley 1990). In this study we apply the magnetic connectivity to the Solar Orbiter measurements from 0.3 AU to 1 AU, to trace back their source at the solar surface using ADAPT magnetograms. The nominal mission phase data are used (from the beginning of 2021). To better approximate the departure time of the plasma at the Sun and the location of its source, we constrain the trajectory of the solar wind using iso-poly modeling (Dakeyo et al. 2022) from the probe location until the source surface Rss. In addition, we aim to follow the classification of Maksimovic et al. 2020 and Dakeyo et al. 2022, to extrapolate sunward the magnetic condition of the different wind speed populations observed by Solar Orbiter.  This statistical analysis shows that the correlation already observed at 1 AU mentioned above (bulk speed, flux tube expansion and magnitude of the magnetic field) are globally conserved getting closer the Sun between 0.3 AU and 1 AU. Depending the speed of the wind we are also able to estimate typical values of expansion factor, magnitude of the coronal magnetic field, the state of charge for each wind speed populations.

How to cite: Dakeyo, J.-B., Rouillard, A., Maksimovic, M., Réville, V., Louarn, P., and Démoulin, P.: Statistical study of the solar wind properties using the magnetic connectivity from in-situ measurements of Solar Orbiter extrapolated sunward the Solar Corona., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6664, https://doi.org/10.5194/egusphere-egu23-6664, 2023.

EGU23-6792 | Posters on site | ST1.3

Electron distribution functions measured by the SWA/EAS sensor during the first perihelia of the Solar Orbiter mission 

Matthieu Berthomier, Andrew Lenc, Georgios Nicolaou, Christopher Owen, Gethyn Lewis, Robert Wicks, Vito Fortunato, and Timothy Horbury

We present an updated procedure developed to calibrate flight data from the Electron Analyser System (EAS) of the Solar Wind Analyzer (SWA) instrument onboard Solar Orbiter. By imposing specific physical conditions on the data set, like isotropy of the core electron population, and by comparing electron fluxes measured by the two EAS heads, we are able to derive consistent correction factors of the raw data set. The procedure is shown to improve the quality of the merging of the two heads dataset. We evaluate the impact of these corrections on ground moment calculation and on specific features of the electron pitch-angle distributions during the first perihelia of the mission. Anisotropy of the component of the pitch-angle electron distribution in different energy ranges is analysed. Detailed properties of specific features of the distribution including strahl and anti-strahl electrons are examined with this updated procedure.

How to cite: Berthomier, M., Lenc, A., Nicolaou, G., Owen, C., Lewis, G., Wicks, R., Fortunato, V., and Horbury, T.: Electron distribution functions measured by the SWA/EAS sensor during the first perihelia of the Solar Orbiter mission, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6792, https://doi.org/10.5194/egusphere-egu23-6792, 2023.

EGU23-7482 | Orals | ST1.3 | Highlight

First results on interplanetary electron events obtained by joint observations of remote-sensing and in-situ instruments on Solar Orbiter 

Alexander Warmuth, Frederic Schuller, Raúl Gómez-Herrero, Javier Rodríguez-Pacheco, Fernando Carcaboso, Sam Krucker, Daniel Pacheco, Robert Wimmer-Schweingruber, Alexander Kollhoff, Nina Dresing, Annamaria Fedeli, David Paipa, Milan Maksimovic, Nicole Vilmer, Krzysztof Barczynski, Olena Podladchikova, Glenn Mason, and Alexis Rouillard and the Joint STIX-EPD-RPW-EUI Working Group

Impulsive electron events observed in interplanetary space are believed to be generated by acceleration in solar flares. This notion has been supported by correlations between the characteristics of energetic electrons detected in-situ near 1 au and those in solar flares derived from hard X-ray observations. However, the details of this relation are still unclear, presumably because of the complex combination of acceleration, injection, and transport effects that are involved.

We present the first statistical results on impulsive electron events obtained by joint observations of remote-sensing and in-situ instruments on Solar Orbiter. We use the suite Energetic Particle Detector (EPD) to measure the properties of the electrons (time profile, anisotropy, maximum energy, inferring the injection time at the source, etc.), as well as to determine the particularities of the composition in the suprathermal energy range. Also, X-ray observations from the Spectrometer/Telescope for Imaging X-rays (STIX) constrain the energetic electrons in the solar flare in terms of timing, spectrum, and location. Type III radio bursts detected by the Radio and Plasma Waves (RPW) instrument are used to link the nonthermal X-ray peaks to the interplanetary electron beams. Finally, the Extreme Ultraviolet Imager (EUI) provides context on the flare evolution. We use a large event sample obtained during the first 2.5 years of the Solar Orbiter mission, which covers a wide range of radial distances ranging from as close as 0.33 au to 1.02 au.

How to cite: Warmuth, A., Schuller, F., Gómez-Herrero, R., Rodríguez-Pacheco, J., Carcaboso, F., Krucker, S., Pacheco, D., Wimmer-Schweingruber, R., Kollhoff, A., Dresing, N., Fedeli, A., Paipa, D., Maksimovic, M., Vilmer, N., Barczynski, K., Podladchikova, O., Mason, G., and Rouillard, A. and the Joint STIX-EPD-RPW-EUI Working Group: First results on interplanetary electron events obtained by joint observations of remote-sensing and in-situ instruments on Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7482, https://doi.org/10.5194/egusphere-egu23-7482, 2023.

EGU23-8088 | ECS | Posters on site | ST1.3

Variations of alpha particle parameters in the non-Alvénic wind 

Tereza Durovcova, Jana Šafránková, and Zdeněk Němeček

Spacecraft observations made at 1 AU from the Sun showed that the solar wind parameters are highly variable. D’Amicis and Bruno (2015) suggested that two solar wind regimes can be distinguished according to the nature of the embedded turbulent fluctuations. If the velocity and magnetic field variations are strongly correlated, Alfvénicity of the fluctuations is high, thus the first solar wind regime is called Alfvénic. Its characteristics suggest that it probably originates from coronal holes. The alpha particle parameters correspond to those usually associated with the fast solar wind. The alpha relative abundance is high (about 4 %) and alpha particles are faster and hotter than protons. The second solar wind regime has embedded non-Alvénic fluctuations. It could come from coronal streamers, but its formation remains unclear. Observations at 1 AU show that the non-Alvénic wind typically has the small alpha-proton relative drift and nearly equal temperature of both ionic components. In our study, we focus on variations of the alpha particle parameters in the non-Alvénic wind and on changes during transition from the Alfvénic to non-Alfvénic winds. We found observations of alpha particles slower than protons, for example near the termination of the corotating rarefaction regions. Using the WIND measurements, we perform a statistical study and compare the plasma properties associated with different ranges of the alpha-proton relative drift. Furthermore, we use measurements from the WIND and Solar Orbiter missions to study changes of the non-Alfvénic wind with increasing distance from the Sun. We discuss their possible origin both in terms of formation near the Sun and during propagation through the interplanetary space.

How to cite: Durovcova, T., Šafránková, J., and Němeček, Z.: Variations of alpha particle parameters in the non-Alvénic wind, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8088, https://doi.org/10.5194/egusphere-egu23-8088, 2023.

EGU23-8269 | ECS | Orals | ST1.3

The Merging of a Coronal Dimming with the Southern Polar Coronal Hole During Solar Orbiter’s First Perihelion 

Nawin Ngampoopun, David Long, Deborah Baker, Lucie Green, Stephanie Yardley, Alexander James, and Andy To

We report a partial filament eruption in the southern solar hemisphere that occurred on 18 March 2022 during the first science perihelion of Solar Orbiter. The filament erupted into a coronal mass ejection (CME), producing coronal dimmings at the footpoints of the erupting structure. The expanding dimming then merged with the adjacent southern polar coronal hole. This merging of two open magnetic structures is observationally rare and poorly understood. We use remote sensing data from multiple co-observing spacecraft to understand the physical processes during this merging event. The evolution of the merger is examined using Extreme-UltraViolet (EUV) images obtained from the instruments onboard the Solar Orbiter and Solar Dynamic Observatory spacecraft. The plasma dynamics are quantified using spectroscopic data obtained from the EUV Imaging Spectrometer onboard Hinode. The preliminary results show that the coronal hole and coronal dimming become indistinguishable from each other after the merging. Several plasma upflow regions were observed throughout the merging event, suggesting the opening of magnetic field lines. The brightening of bright points and coronal jets inside the merged region further imply ongoing reconnection processes. This work also has implications for the formation of coronal hole/open field regions and the origin of solar wind from coronal dimming and coronal hole boundaries.

How to cite: Ngampoopun, N., Long, D., Baker, D., Green, L., Yardley, S., James, A., and To, A.: The Merging of a Coronal Dimming with the Southern Polar Coronal Hole During Solar Orbiter’s First Perihelion, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8269, https://doi.org/10.5194/egusphere-egu23-8269, 2023.

EGU23-8923 | Orals | ST1.3 | Highlight

Solar Orbiter: The Sun up close 

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

The ESA/NASA Solar Orbiter mission performed its first close solar encounters at 0.32 au in March 2022 and at 0.29 au in October 2022. By combining high-resolution imaging and spectroscopy of the Sun with detailed in-situ measurements of the surrounding heliosphere, Solar Orbiter enables us to study the Sun's corona in unprecedented detail, and determine the linkage between observed solar wind streams and their source regions on the Sun. Its science return will be enhanced significantly by coordinated observations with other space missions, e.g. Parker Solar Probe, as well as new ground-based telescopes like DKIST. Over the course of the 10-year mission, Solar Orbiter's highly elliptical orbit will get progressively more inclined to the ecliptic plane. Thanks to this new perspective, Solar Orbiter will deliver images and comprehensive data of the unexplored Sun’s polar regions and the Sun's far side. This talk will provide a status update of the mission and the science operations performed during the first two science perihelia, and summarise early science results.

How to cite: Zouganelis, Y., Müller, D., De Groof, A., Williams, D., Walsh, A., Janvier, M., Nieves-Chinchilla, T., Lario, D., and Musset, S.: Solar Orbiter: The Sun up close, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8923, https://doi.org/10.5194/egusphere-egu23-8923, 2023.

EGU23-9221 | Orals | ST1.3

Evidence for External Reconnection Between an EruptingMini-filament and Ambient Loops Observed by Solar Orbiter/EUI 

Zhuofei Li, Xin Cheng, Mingde Ding, Pradeep Chitta, Hardi Peter, and David Berghmans

Mini-filament eruptions are one of the most common small-scale transients in the solar atmosphere. However, their eruption mechanisms are still not understood thoroughly. Here, with a combination of 174 Åimages of high spatio-temporal resolution taken by the Extreme Ultraviolet Imager on board Solar Orbiter and images of the Atmospheric Imaging Assembly on board Solar Dynamics Observatory, we present a detailed investigation of an erupting mini-filament over a weak magnetic field region on 2022 March 4. It is clearly observed that, as the mini-filament quickly ascends, two ribbons appear underneath it. Subsequently, when the erupting mini-filament interacts with the outer ambient loops, some dark materials blow out, forming a blowout jet characterized by a widening spire. At the same time, multiple small bright blobs of size 1–2 Mm appear at the interaction region and propagate along the post-eruption loops towards the footpoints of the erupting fluxes at a speed of  100 km s􀀀1, as well as giving rise to a semi-circular brightening. These features indicate that the mini-filament eruption first undergoes the internal and then external reconnection, the latter of which mainly transfers mass and magnetic flux of the erupting mini-filament to the ambient corona.

How to cite: Li, Z., Cheng, X., Ding, M., Chitta, P., Peter, H., and Berghmans, D.: Evidence for External Reconnection Between an EruptingMini-filament and Ambient Loops Observed by Solar Orbiter/EUI, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9221, https://doi.org/10.5194/egusphere-egu23-9221, 2023.

EGU23-9380 | Posters on site | ST1.3

Modeling EUV intensity at the top of the transition region using SPICE data on board Solar Orbiter 

Jenny Marcela Rodríguez Gómez, Therese Kucera, and Peter Young

The Spectral Imaging of Coronal Environment (SPICE; SPICE Consortium et al. 2020) provides an extraordinary opportunity to study the chromosphere and transition region using EUV wavelengths, e.g., Ne VIII 770 Å, C III 977 Å, O VI 1032 Å, and Lyman-β 1025 Å. We present preliminary results modeling Ne VIII 770 Å intensity using images from SPICE and the COronal DEnsity and Temperature (CODET) model. This model is based on relationships between the magnetic field, density, and temperature. It uses a flux transport model, the Potential Field Extrapolation model (PFSS), an emission model based on Chianti atomic database 10.0.2, and an optimization algorithm. In addition, we assume that the emission from the top of the transition region (Ne VIII 770 Å) can be described using the magnetic field in the coronal base at 1.014 RSun (from PFSS).

How to cite: Rodríguez Gómez, J. M., Kucera, T., and Young, P.: Modeling EUV intensity at the top of the transition region using SPICE data on board Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9380, https://doi.org/10.5194/egusphere-egu23-9380, 2023.

EGU23-9386 | Posters on site | ST1.3

Recurrent 3He-rich solar energetic particle injections observed by Solar Orbiter at ~0.5 au 

Radoslav Bucik, Glenn M. Mason, Nariaki V. Nitta, Vratislav Krupar, Luciano Rodriguez, George C. Ho, Samuel T. Hart, Maher A. Dayeh, Javier Rodríguez-Pacheco, Raúl Gómez-Herrero, and Robert F. Wimmer-Schweingruber

We report Solar Orbiter observations of six recurrent solar energetic particle injections in 2022 March 3–6 at ~0.5 au. The injections were associated with jets emanating from a plage near a large sunspot in NOAA active region 12957. We saw large jets in injections with high 3He and Fe enrichments and minor jets in injections with no or lower enrichments. Furthermore, the event with the highest enrichment showed a more compact configuration of the underlying photospheric magnetic field. The higher fluences as well as harder spectra were seen in the event with a wider jet-like eruption. However, in this case, the buildup time might be required to produce such spectra. Extreme ultraviolet images from Solar Orbiter revealed a crisscrossing network at the base of jets not seen from 1 au that might be suitable for the recurrent events.

How to cite: Bucik, R., Mason, G. M., Nitta, N. V., Krupar, V., Rodriguez, L., Ho, G. C., Hart, S. T., Dayeh, M. A., Rodríguez-Pacheco, J., Gómez-Herrero, R., and Wimmer-Schweingruber, R. F.: Recurrent 3He-rich solar energetic particle injections observed by Solar Orbiter at ~0.5 au, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9386, https://doi.org/10.5194/egusphere-egu23-9386, 2023.

EGU23-11354 | Orals | ST1.3

Energetic electrons in the solar corona  for the long duration event of 9 May 2021 as diagnosed from X-ray and radio observations. 

Nicole Vilmer, Sophie Musset, Minghui Zhang, Karl-Ludwig Klein, and David Paipa

In this paper we will present preliminary results of an X-ray flare that occurred on 9th May 2021 for which the thermal and non-thermal X-ray signatures were detected both from the Earth direction by Fermi/GBM  and by STIX on Solar Orbiter at 97° from the Sun-Earth line.  This flare was also well observed in radio with the ground-based instruments  in Nançay and in the interplanetary space by WIND/WAVES and RPW on Solar Orbiter . The X-ray event shows both an impulsive phase observed above 25 keV by STIX and FERMI and followed by a more gradual phase observed up to 15 keV by both STIX and FERMI. In the decimetric/metric radio domain, this event shows a group of type III bursts extending to the interplanetary medium as well as type IV emission.  We shall discuss here the relative temporal evolutions of HXR emissions at different energies with those of the radio fluxes at different frequencies, as well as the spatial evolution of the X-ray and radio sources during the different phases of the event. We shall also investigate the evolution of the characteristics of the non-thermal electrons detected in the corona associated to both implusive and gradual phase of the flare.

How to cite: Vilmer, N., Musset, S., Zhang, M., Klein, K.-L., and Paipa, D.: Energetic electrons in the solar corona  for the long duration event of 9 May 2021 as diagnosed from X-ray and radio observations., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11354, https://doi.org/10.5194/egusphere-egu23-11354, 2023.

EGU23-11801 | ECS | Orals | ST1.3 | Highlight

SOL2022-03-30 X1.4 GOES Class Flare: Localising the source of quasi periodic pulsations in the Hard X-ray and microwave emissions with STIX onboard Solar Orbiter and EOVSA. 

Hannah Collier, Laura Hayes, Andrea Battaglia, Louise Harra, and Säm Krucker

In this work the analysis of the SOL2022-03-30 X1.4 GOES class flare is presented. This flare was observed by Solar Orbiter during perihelion as well as from Earth based observatories including SDO’s AIA and the Extended Owens Valley Solar Array (EOVSA). It displays well correlated fast time variation in the HXR and microwave wavelengths of emission with time dependent lags. The mechanism behind such observed puslations is not yet fully understood and is important for gaining an understanding of particle acceleration and energy release in solar flares. In this flare, the oscillatory behaviour grows in time and can be split into three phases with QPP periods ~7s, ~14s and ~35s. New capabilities from Solar Orbiter’s Spectrometer Telescope for Imaging X-rays (STIX) allows for the localisation of individual bursts on short timescales which enables us to determine the spatial morphology of the HXR emission and its evolution in time. The HXR source locations are compared with the microwave sources observed by EOVSA and the ribbon structure determined from AIA 1600Å and 1700Å. The QPP source locations are found to change significantly in time. Furthermore, the electron spectral index is anti-correlated with the observed HXR emission, obeying the soft-hard-soft relation. When combined, these observations point towards a mechanism for QPP generation which involves quasi-periodic energy release and injection of electrons into the flaring loop. However, several open questions remain about how these QPPs are generated.  

How to cite: Collier, H., Hayes, L., Battaglia, A., Harra, L., and Krucker, S.: SOL2022-03-30 X1.4 GOES Class Flare: Localising the source of quasi periodic pulsations in the Hard X-ray and microwave emissions with STIX onboard Solar Orbiter and EOVSA., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11801, https://doi.org/10.5194/egusphere-egu23-11801, 2023.

EGU23-12027 | ECS | Orals | ST1.3

Multi-spacecraft observations of near-relativistic electron events at different radial distances 

Alexander Kollhoff, Lars Berger, Maximilian Brüdern, Nina Dresing, Sandra Eldrum, Sebastian Fleth, Raúl Gómez-Herrero, Bernd Heber, Patrik Kühl, Daniel Pacheco, Laura Rodríguez-García, Javier Rodríguez-Pacheco, Robert F. Wimmer-Schweingruber, and Zigong Xu

With the launch of Solar Orbiter (SolO) on Feb. 10th 2020, a new era of multi-spacecraft solar energetic particles (SEP) observations has started. The unique orbit of the mission allows the observation of SEP events close to the Sun (<0.28 au), which can occasionally be compared to corresponding observations made by other spacecraft at 1au. Such multi-spacecraft observations of the same event at different radial distances provide an excellent opportunity to study the radial evolution of SEP events.

In this study, we identify SEP events for which SolO and either Wind or STEREO-A had a small longitudinal separation (<15°) between their magnetic foot-points at the Sun. For all SEP events that satisfy our selection criteria we determine the onset times and rise times as well as peak fluxes and peak values of the first-order anisotropy for electrons in the energy range from ∼50−85 keV. We compare the event parameters observed at the different spacecraft regarding their radial changes. In our sample we find strong event-to-event variations in the radial dependency of all derived event parameters. For the majority of events, the peak flux and the maximum value of the first-order anisotropy decrease with increasing radial distance to the Sun, while the rise time increases with radial distance in the majority of events. The derived onset delays observed between two spacecraft were found to be too long to be explained by ideal Parker spirals in multiple events.

We present an overview of the most interesting observations and discuss the wide variability in the radial dependency of the event parameters analysed in this study.

How to cite: Kollhoff, A., Berger, L., Brüdern, M., Dresing, N., Eldrum, S., Fleth, S., Gómez-Herrero, R., Heber, B., Kühl, P., Pacheco, D., Rodríguez-García, L., Rodríguez-Pacheco, J., Wimmer-Schweingruber, R. F., and Xu, Z.: Multi-spacecraft observations of near-relativistic electron events at different radial distances, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12027, https://doi.org/10.5194/egusphere-egu23-12027, 2023.

EGU23-12502 | Posters on site | ST1.3 | Highlight

Investigating the Source of the Slow Solar Wind Using Solar Orbiter Observations and the IRAP Solar Atmospheric Model 

Simon Thomas, Alexis Rouillard, Michael Lavarra, Nicolas Poirier, and Pierre-Louis Blelly

The slow solar wind can be separated into at least two different components: a dense, variable wind produced by helmet streamers and a more tenuous and Alfvénic component emitted by coronal holes. Previous studies have shown that the slow Alfvénic wind is associated with enhanced alpha particle abundances, strong proton beams, and large alpha-to-proton temperature ratios: typical properties of the fast wind known to originate from inside large coronal holes. Recent combined in-situ and remote-observation campaigns by the Solar Orbiter mission exploiting the Proton and Alpha particle Sensor (SWA-PAS) can help us to study the relationship between the Alfvénic slow wind and coronal holes. We exploit these latest observations in conjunction with the newly-developed multi-species IRAP Solar Atmospheric Model (ISAM) model to study the coronal conditions that favour the production of an Alfvénic slow wind. ISAM simulates 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, as well as detailed energy and heat flux conservation equations. In this study we discuss how the simulated alpha to proton ratios are modulated in response to different coronal heating rates and discuss these simulation results in light of recent Solar Orbiter measurements. The results presented here were funded by the European Research Council through the SLOW SOURCE project grant number DLV-819189.

How to cite: Thomas, S., Rouillard, A., Lavarra, M., Poirier, N., and Blelly, P.-L.: Investigating the Source of the Slow Solar Wind Using Solar Orbiter Observations and the IRAP Solar Atmospheric Model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12502, https://doi.org/10.5194/egusphere-egu23-12502, 2023.

EGU23-13249 | Orals | ST1.3

Behavior of Flare-associated Suprathermal Ions at Coronal Mass Ejections observed with Solar Orbiter at 0.5 AU 

Nils Janitzek, Mario Moraleda, Andrew Walsh, Glenn Mason, Raúl Gomez-Herrero, Alexander Kollhoff, Daniel Pacheco, Krzysztof Barcynski, Laura Rodríguez-García, Sophie Musset, Laura Hayes, Ioannis Zouganelis, George Ho, Robert Wimmer-Schweingruber, and Javier Rodríguez-Pacheco

Flare-associated particles from so-called impulsive events might be efficiently reaccelerated in gradual Solar Energetic Particle (SEP) events which are typically related to coronal mass ejections (CMEs). The existence and characteristics of such a flare-associated seed population might play a key role for understanding the high variability in particle intensity under comparable CME speeds and solar wind conditions. Understanding this variability will improve predictions of large gradual SEP events that cause a severe risk for satellite and even ground-based infrastructure. We analyze a sequence of impulsive and subsequent gradual events that occurred between 5 and 11 March 2022 and were measured in-situ with Solar Orbiter at a close distance of 0.5 AU to the Sun. We study in detail the behavior of suprathermal ions during the events and relate it to the ambient solar wind plasma properties and remote-sensing observations of the respective flares and CMEs observed from SOHO, SDO, and Solar Orbiter. We find in particular a strong local enhancement of suprathermal flare-associated ions that are trapped for several hours between two ICME structures and provide therefore a natural reservoir of seed particles that can be efficiently further accelerated in ambient compression regions or occurring shocks on their way out to 1 AU.

 

How to cite: Janitzek, N., Moraleda, M., Walsh, A., Mason, G., Gomez-Herrero, R., Kollhoff, A., Pacheco, D., Barcynski, K., Rodríguez-García, L., Musset, S., Hayes, L., Zouganelis, I., Ho, G., Wimmer-Schweingruber, R., and Rodríguez-Pacheco, J.: Behavior of Flare-associated Suprathermal Ions at Coronal Mass Ejections observed with Solar Orbiter at 0.5 AU, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13249, https://doi.org/10.5194/egusphere-egu23-13249, 2023.

EGU23-13609 | Posters on site | ST1.3

Heavy-ion-rich X-ray solar flares in December 2022 measured on Solar Orbiter 

Oleksiy Dudnik, Glenn Mason, George Ho, Robert Allen, Robert Wimmer-Schweingruber, Javier Rodríguez-Pacheco, Francisco Espinosa Lara, Raul Gómez Herrero, Tomasz Mrozek, and Marian Karlicky

   Energy spectra of X-ray solar flares observed by the Spectrometer-Telescope for Imaging X-rays (STIX) onboard the Solar Orbiter consist of both thermal and non-thermal parts. The thermal part is present in all solar events. When the non-thermal part of the energy spectrum begins to dominate, we can expect detection in interplanetary space of high-energy electron beams that have escaped the coronal loops. When hard X-ray flares are detected solar type III radio bursts are registered frequently with their numerous modifications like drift pairs, U-type, and structured bursts. The e-CALLISTO simple worldwide radio antenna stations allow us to identify the existence of non-thermal components in the energy spectra of strong X-ray flares. At the same time, some X-ray flares are accompanied by ejections of energetic ions including heavy ions. The specific features in X-ray bursts responsible for events with simultaneous light and heavy particle stream generation are still unclear compared with those with electron emission only.

    We present preliminary results of observations gathered in December 2022 and cross-analysis of data on energetic light and heavy particle fluxes and X-ray flare parameters. The end of 2022 was distinguished by moderate to high solar activity, the presence of three periods with enhanced proton and heavy-ion fluxes at the beginning of the month, in the middle, and on 25-26 December. We demonstrate also the presence of narrow directed electron beams detected by the Electron Proton Telescope (EPT) of EPD for selected events mentioned above, and heavy ions detected by the Suprathermal Ion Spectrograph (SIS) of EPD.

How to cite: Dudnik, O., Mason, G., Ho, G., Allen, R., Wimmer-Schweingruber, R., Rodríguez-Pacheco, J., Espinosa Lara, F., Gómez Herrero, R., Mrozek, T., and Karlicky, M.: Heavy-ion-rich X-ray solar flares in December 2022 measured on Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13609, https://doi.org/10.5194/egusphere-egu23-13609, 2023.

EGU23-13784 | Orals | ST1.3

A multi-thermal analysis of M-class flare observed  in common by STIX and XSM 

Anna Kepa, Marek Siarkowski, Arun Kumar Awasthi, Barbara Sylwester, and Janusz Sylwester

During nearly three years of operation, STIX aboard Solar Orbiter observed thousands of flares.   Many of them were simultaneously observed by Solar X-Ray Monitor (XSM) on board Indian Chandrayaan-2 circling the Moon.  We present results of a multi-wavelength study for  one selected flare  of M GOES class as seen from 1.a.u. STIX data provided  the opportunity for a detailed analysis of hard X-ray emission in several energy bands including the light curves, reconstructed hard X-ray images and spectra. The differential emission measure diagnostics of the flaring plasma have been carried out based on interpretation of the XSM X-ray spectra. Using the differential evolution (DE) approach we have determined the “full” model of emitting source including the temperature, emission measure and elemental abundances as determined simultaneously throughout the flare.  We discuss patterns of elemental composition history for individual plasma temperature components.

How to cite: Kepa, A., Siarkowski, M., Awasthi, A. K., Sylwester, B., and Sylwester, J.: A multi-thermal analysis of M-class flare observed  in common by STIX and XSM, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13784, https://doi.org/10.5194/egusphere-egu23-13784, 2023.

EGU23-14396 | Posters on site | ST1.3

Triple coronal Hard X-Ray source observed by STIX during a failed eruption of a filament. 

Tomasz Mrozek, Marek Stęślicki, Sylwester Kołomański, and Krzysztof Barczyński

Solar Hard X-Ray (HXR) emission is observed typically in the form of localized, rather compact sources. Majority of these sources are flare related, however there is growing evidence, observational and theoretical, that we can expect HXR emission from places not directly related to primary energy release regions. From this point of view, failed eruptions are phenomena which are very interesting. Failed eruptions are events which at an early phase develop like a typical eruption which evolves into CME. However, for unclear reasons these eruptions stop abruptly somewhere in the solar corona. Many mechanisms are suspected to be responsible for stopping an eruption i.e. kink instability leading to stable configuration of erupting flux tube, magnetic tension within erupting structure or interaction and reconnection with an overlying coronal magnetic field. The last one may lead to electron acceleration and production of high temperature regions emitting in the HXR. There are only a few observations, from past instruments, showing some evidence of HXR production in failed eruptions. Recently, the Solar Orbiter has been launched giving a completely new perspective for observation and analysis of coronal dynamic events. Apart from others, it carries onboard Extreme-Ultraviolet Imager (EUI) and Spectrometer/Telescope for Imaging X-rays (STIX) telescopes open an opportunity to understand the physics of failed eruptions. The new EUV and HXR observations are important for at least two reasons. First, SO can approach the Sun closer than 0.3 a.u. which increase spatial resolution and sensitivity of telescopes, giving ocasion for registering weak HXR sources which can not be observed with previous instruments. Second, SDO/AIA instrument operating on the Earth orbit can provide stereoscopic context for SO/EUI images which may help to investigate deeper the geometry of the eruption and causes of its braking. Here, we present a very well observed flare accompanied by a failed eruption. The event occurred when longitudinal separation of the Earth and SO was 17 degrees. From the Earth perspective the event was visible very close to the west limb of a solar disc. For SO it was a behind-the-limb event with occulted footpoints which gave us a very good view, especially in the HXR range, of emission coming from the solar corona. During a flare's impulsive phase, the eruption accelerated to the velocity of a few hundreds kilometers per second and after six minutes it stopped abruptly at the height of 100 000 km above the solar surface. The eruption reconnected with overlying coronal loops leading to occurrence of at least three regions observed by STIX. The lowest source seems to be a typical, flare related coronal source, possibly consisting of two spatially unresolved sources located close to the primary reconnection site. The other two sources are located higher in the corona where reconnection of the eruption with an overlying magnetic field was observed. These sources behave significantly differently than the lowest source. Namely, their evolution is more gradual and seems to be driven by direct heating not the evaporation of chromospheric plasma which is a case for the lowest source.

How to cite: Mrozek, T., Stęślicki, M., Kołomański, S., and Barczyński, K.: Triple coronal Hard X-Ray source observed by STIX during a failed eruption of a filament., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14396, https://doi.org/10.5194/egusphere-egu23-14396, 2023.

EGU23-14698 | ECS | Posters on site | ST1.3

Anisotropies of solar energetic electrons in the MeV range measured with SolO/EPD/HET 

Sebastian Fleth, Patrick Kühl, Alexander Kollhoff, Robert F. Wimmer-Schweingruber, Bernd Heber, Javier Rodríguez-Pacheco, and Nina Dresing

Solar Orbiter is an ESA-led mission of international collaboration with NASA to investigate how the Sun creates and controls the heliosphere, and why solar activity changes with time. One of its top-level science questions is how solar eruptions produce energetic particle radiation that fills the heliosphere. With its four viewing directions the High-Energy telescope (HET) provides critical information about the sources and transport of high-energy particles.

This study analyses relativistic electron measurements obtained by HET in the energy range from 200 keV to above 10 MeV. The purpose of this study is to analyse anisotropies of relativistic solar energetic electrons utilizing the different viewing directions of HET. Time periods with enhanced fluxes of relativistic electrons, have been identified. A list of these time periods including additional observations such as maximum energy and flux as well as the first order anistropy will be presented. This is the first time since the Helios mission that anisotropies of high energy electrons have been measured.

How to cite: Fleth, S., Kühl, P., Kollhoff, A., Wimmer-Schweingruber, R. F., Heber, B., Rodríguez-Pacheco, J., and Dresing, N.: Anisotropies of solar energetic electrons in the MeV range measured with SolO/EPD/HET, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14698, https://doi.org/10.5194/egusphere-egu23-14698, 2023.

EGU23-14916 | Posters on site | ST1.3

The energy-altitude relation in solar flare footpoints observed by STIX 

Katarzyna Mikuła and Tomasz Mrozek

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 decreses with incresing 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 (>M1.0 GOES class) events recorded by the Spectrometer/Telescope for Imaging X-rays (STIX) onboard the Solar Orbiter. Here we present the results of analysis of the relation obtained from STIX data, e.g. temporal evolution and density distributions on selected examples. 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: Mikuła, K. and Mrozek, T.: The energy-altitude relation in solar flare footpoints observed by STIX, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14916, https://doi.org/10.5194/egusphere-egu23-14916, 2023.

EGU23-15283 | Orals | ST1.3 | Highlight

Using non-thermal electron distributions to probe the inner heliosphere 

Daniel Verscharen, Christopher Owen, Georgios Nicolaou, Jesse Coburn, Alfredo Micera, and Maria Elena Innocenti

The electrons in the solar wind exhibit non-thermal velocity distribution functions. Observed non-thermal features of the electron distribution in the inner heliosphere include the field-aligned strahl, the suprathermal halo, the sunward deficit, and temperature anisotropy. These features are the result of a complex interplay between global expansion effects 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 reflections in the interplanetary electric field. Local wave-particle interactions such as instabilities change the shape of these features and thus the overall properties and moments of the electron distribution.

We discuss the science opportunities that the high-resolution data of Solar Orbiter's SWA/EAS sensor open up for unprecedented studies of the causes and effects of non-thermal electron distributions in the context of the expansion of the solar wind in the inner heliosphere. We focus, in particular, on the interplay between expansion effects and instabilities related to the electron strahl and the sunward deficit.

How to cite: Verscharen, D., Owen, C., Nicolaou, G., Coburn, J., Micera, A., and Innocenti, M. E.: Using non-thermal electron distributions to probe the inner heliosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15283, https://doi.org/10.5194/egusphere-egu23-15283, 2023.

EGU23-15516 | ECS | Orals | ST1.3

Possible Role of Fluctuation Excitation in the Formation of Alfvénic Fluctuations Originating from Interchange Magnetic Reconnection 

Chuanpeng Hou, Alexis Rouillard, Jiansen He, Bahaeddine Gannouni, and Victor Réville

Parker Solar Probe has detected abundant magnetic inversions and velocity spikes in the young solar wind, the origins of which are still highly debated. Numerous studies based on observational data and numerical simulations favor the causal correlation between interchange magnetic reconnection process and these velocity spikes. However, the specific process by which interchange magnetic reconnection leads to these structures is still inconclusive. Interchange reconnection should occur during the eruption of small bipoles in pre-existing open magnetic field regions such as coronal holes. This process is known to drive the formation of plumes and pseudo-streamer like structures and potentially mesoscale structures measured in the solar wind as well as velocity spikes. Using velocity measurements from Solar Orbiter we infer the magnetic origin of mesoscale structures and velocity spikes measured by Solar Orbiter, we find that the footpoints of the magnetic lines associated with these spikes are located at the boundary of a coronal hole observed by the Solar Dynamics Observatory (SDO), where the interchange magnetic reconnection is likely to occur. The imaging instruments aboard Solar Orbiter and SDO record one typical interchange magnetic reconnection event near the footpoints. With the high temporal/spatial resolution images obtained from multiple perspectives, we directly analyze the fluctuating motion of jet flow materials and explore the mechanism of fluctuation excitation during the interchange magnetic reconnection. We compare our observations with a 2.5D MHD simulation of interchange magnetic reconnection, we speculate that outward fluctuations may act as a kind of mediator between interchange magnetic reconnection and the formation process of velocity spikes/magnetic switchbacks.

How to cite: Hou, C., Rouillard, A., He, J., Gannouni, B., and Réville, V.: Possible Role of Fluctuation Excitation in the Formation of Alfvénic Fluctuations Originating from Interchange Magnetic Reconnection, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15516, https://doi.org/10.5194/egusphere-egu23-15516, 2023.

EGU23-15579 | ECS | Orals | ST1.3 | Highlight

Identifying the source of multi-spacecraft SEP events 

Maximilian Bruedern, Nina Dresing, Bernd Heber, Yulia Kartavykh, Alexander Kollhoff, Patrick Kühl, and Du Toit Strauss

With the launch of Solar Orbiter (SolO) together with STEREO A, and Wind it is again possible to study  multi-spacecraft Solar Energetic Particle (SEP) events within 1 AU. Over the timespan from July 2020 up to June 2022, we identify 44 events for which a significant increase of ∼100 keV electrons has been observed for at least two spacecraft. The maximum longitudinal separation of the two furthest spacecraft ranges from ∼17 to ∼217 degree. 

SEPs are expected to follow the Interplanetary Magnetic Field (IMF) which in zero-order approximation has the shape of Parker spirals. We investigate two different scenarios to identify the source of the widespread particle observation: (a) Particles are injected over a broad range of longitudes at the source surface without any perpendicular transport, hence by propagating along the IMF SEPs can be detected for distant observers. (b) Particles are injected over a narrow range of longitudes, but are distributed perpendicular to the nominal IMF by perpendicular diffusion. We discard events for which no unambiguously source location (e.g., flare) can be identified, or where an interplanetary coronal mass ejection is present. In order to investigate these scenarios a 2d  SEP transport model is utilized. The simulated data are compared to selected SEP observations. We developed a χ2 minimization code in order to determine the most probable injection and transport parameters.

Here, we present our first modeling results for a selected number of multi-spacecraft SEP events involving SolO. Furthermore, we note that the multi-spacecraft event observation can be a result of a combination of case (a) and (b).

How to cite: Bruedern, M., Dresing, N., Heber, B., Kartavykh, Y., Kollhoff, A., Kühl, P., and Strauss, D. T.: Identifying the source of multi-spacecraft SEP events, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15579, https://doi.org/10.5194/egusphere-egu23-15579, 2023.

EGU23-15710 | ECS | Orals | ST1.3

Time-normalized plasma flow mapping during the quadrature of SolO and SDO 

Gabriel Muro and Huw Morgan

Observations of plasma motions in the low corona are often limited to magnetic field lines originating in active regions, which are ideal for spatial domain enhancements across individual extreme ultraviolet (EUV) images to see loops, flares, and other bright activity contrasted against dim background features.

The quiet Sun is essentially all dim background features, which requires advanced image processing and ideal observation parameters to emphasize the temporal domain in order to visualize faint, fine-scale plasma flows. We utilize time-normalized optical flow (TNOF) on large sets of high cadence EUV data by reducing instrumental noise to a high degree and then emphasizing the minor brightness variations indicative of plasma motion. Maps of plasma flow paths are produced via optical flow tracking algorithms by the computer vision method of Lucas-Kanade and the underlying velocity field is estimated with line integral convolution.

To test the effectiveness of the TNOF approach, we have applied this method to an EUV case study of data from EUI 174 and AIA 171 on 29 March 2022. This date marked a near-perpendicular line of sight orientation between the two spacecraft, had similarly short observation intervals, and provided the opportunity to compare contrast enhanced plasma features off-limb with temporally enhanced on-disk plasma motion. 

In this case study, we generated movies and flow paths that show TNOF succeeds at qualitatively outlining plasma flow along magnetic field lines from both Solar Orbiter’s and SDO’s point of view which are in general agreement with potential field models. Additionally, detailed velocities of plasma motion within coronal loops, overall velocity trends, and a new quasi-magnetic flow trend within the quiet Sun are presented.

How to cite: Muro, G. and Morgan, H.: Time-normalized plasma flow mapping during the quadrature of SolO and SDO, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15710, https://doi.org/10.5194/egusphere-egu23-15710, 2023.

EGU23-16072 | Orals | ST1.3 | Highlight

Solar Orbiter reveals that reconnection jets cluster in the solar wind 

Naïs Fargette, Benoit Lavraud, Alexis Rouillard, Pierre Houdayer, Tai Phan, Marit Oieroset, Jonathan Eastwood, Andrei Fedorov, Philippe Louarn, Christopher Owen, and Tim Horbury

Magnetic reconnection is a fundamental process in astrophysical plasma, as it enables the dissipation of energy at kinetic scales. Detecting it in-situ is therefore key to further our understanding of energy conversion in space plasma. However, ion reconnection jets usually scale from seconds to minutes in-situ, and as such they can be quite tedious to find in the months or years of data provided by Wind, ACE, Helios, PSP and Solar Orbiter.

In this work, we use a new approach to identify automatically reconnection exhausts in-situ. The method strongly relies on the Walén relation and uses Bayesian inference as well as physical considerations to detect reconnection jets in-situ. Applying the detection algorithm to one month of Solar Orbiter data at 0.7 ~AU, we find an occurrence rate of 6.4~jets/day, which is significantly higher than in previous studies performed at 1~AU.  We repeat the analysis over the Solar Orbiter perihelion at 0.3 AU and show that the occurrence rate of magnetic reconnection tends to increase with radial distance.

We show that magnetic reconnection exhausts clearly cluster in the solar wind. We perform a statistical analysis, distinguishing between the exhausts associated with the heliospheric current sheet and turbulent reconnection. We find that the source and the degree of Alfvénicity of the solar wind might have an impact on magnetic reconnection occurrence.

How to cite: Fargette, N., Lavraud, B., Rouillard, A., Houdayer, P., Phan, T., Oieroset, M., Eastwood, J., Fedorov, A., Louarn, P., Owen, C., and Horbury, T.: Solar Orbiter reveals that reconnection jets cluster in the solar wind, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16072, https://doi.org/10.5194/egusphere-egu23-16072, 2023.

EGU23-16350 | Orals | ST1.3

Detailed look at the temporal correlation between hard X-ray flare and type III radio bursts 

Shilpi Bhunia, Laura Hayes, Shane Maloney, and Peter Gallagher

It is well known that flare-accelerated electrons can produce both 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 while Type-III radio bursts are produced by the accelerated electron beams traveling towards 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 allows 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 I-LOFAR, WIND/WAVES, NDA and ORFEES. I-LOFAR provides high-sensitivity imaging spectroscopy in the range of ~10-240 MHz with a time resolution of 1.31 ms and a frequency resolution of 195 kHz. We examine the temporal correlation between the X-ray and radio time series and discuss the relationship between the two and what it implies   about the origin of the electron populations producing these two kinds of radiation.

How to cite: Bhunia, S., Hayes, L., Maloney, S., and Gallagher, P.: Detailed look at the temporal correlation between hard X-ray flare and type III radio bursts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16350, https://doi.org/10.5194/egusphere-egu23-16350, 2023.

EGU23-1094 | Orals | ST1.4

Magnetotail plasmoid eruption: Interplay of instabilities and reconnection 

Minna Palmroth and the Team

Rapid plasma eruptions explosively release energy in the Earth’s magnetosphere, at the Sun, and solar system planets. At Earth, these eruptions, termed plasmoids, occur in the magnetospheric nightside, and are associated with the sudden brightening of the aurora. The chain of events leading to the plasmoid is one of the longest-standing unresolved questions in space physics. Two competing paradigms, based on magnetic reconnection or kinetic instabilities, are proposed to explain the course of events. We report results of a major technological achievement modelling the Earth’s magnetosphere at realistic scales, with sufficient spatiotemporal resolution, and resolving ion-kinetic physics, and thereby capturing physics essential to both paradigms. We show that both magnetic reconnection and kinetic instabilities are required to induce a global topological reconfiguration of the magnetotail, thereby combining the seemingly contradictory paradigms. Our results show that magnetic reconnection creates local plasmoids that are combined into a tail-wide structure by a current sheet disruption in the center tail. Large-scale current sheet flapping, caused by a drift kink instability and driven by reconnection-generated ions, leads to the current disruption. Our results help to understand plasma eruptions ubiquitous in space plasmas, guide spacecraft constellation mission design, and lead to improved understanding of space weather. We also contemplate the future direction of models within the solar system plasma physics and heliophysics discipline.

How to cite: Palmroth, M. and the Team: Magnetotail plasmoid eruption: Interplay of instabilities and reconnection, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1094, https://doi.org/10.5194/egusphere-egu23-1094, 2023.

EGU23-2060 | Posters on site | ST1.4

Turbulent magnetic reconnection in the solar wind 

Rongsheng Wang, Xinmin Li, Shimou Wang, Quanming Lu, San Lu, and Walter Gonzalez

Turbulent magnetic reconnection was observed in the magnetotail and the magnetopause. In turbulent magnetic reconnection, the diffusion region is filled with a number of filamentary currents primarily carried by the electrons and some flux ropes. These dynamic filamentary currents constitute a kind of three-dimensional network in the diffusion region and lead the reconnection into turbulence. The electrons are trapped and sufficiently accelerated inside such a complicated current network.

According to the previous observations, magnetic reconnection generally displays a quasi-steady state in the solar wind, where the energy is dissipated via slow-mode shocks. It is elusive why the reconnection in the solar wind is quasi-steady. Here we present a direct observation of bursty and turbulent magnetic reconnection in the solar wind, with its associated exhausts bounded by a pair of slow-mode shocks. We infer that the plasma is more efficiently heated in the magnetic reconnection diffusion region than across the shocks and that the flow enhancement is much higher in the exhausts than in the area around the diffusion region. We detected 75 other, similar diffusion-region events in solar wind data between October 2017 and May 2019, suggesting that bursty reconnection in the solar wind is more common than previously thought and actively contributes to solar wind acceleration and heating.

How to cite: Wang, R., Li, X., Wang, S., Lu, Q., Lu, S., and Gonzalez, W.: Turbulent magnetic reconnection in the solar wind, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2060, https://doi.org/10.5194/egusphere-egu23-2060, 2023.

EGU23-2179 | Orals | ST1.4

Open questions in heliophysics: terrestrial laboratory 

Elena Kronberg

The heliosphere is a part of the Universe in which we can do in situ measurements of plasma dynamics under diverse conditions. The terrestrial magnetosphere is especially well accessible for studying universal plasma processes, in particular those associated with the conversion and flow of electromagnetic and plasma energy. To fully understand phenomena such as shocks, instabilities at plasma boundaries, and magnetic reconnection it is crucial to consider the coupling between physical processes at small and large scales. Planetary magnetospheric systems are not completely understood, because kinetic and global scales are rarely measured simultaneously. In most observations, the energy range and composition are not resolved for all important contributors.  The mentioned aspects are essential for an assessment of the magnetosphere-ionosphere-atmosphere-subsurface coupling and for the prediction of space weather. The influence of ionospheric charged particles on the magnetospheric dynamics will be used as an illustrative example. 

How to cite: Kronberg, E.: Open questions in heliophysics: terrestrial laboratory, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2179, https://doi.org/10.5194/egusphere-egu23-2179, 2023.

EGU23-3258 | ECS | Orals | ST1.4

Radial Diffusion Benchmarking: Initial Conditions 

Sarah Bentley, Jen Stout, Daniel Ratliff, Rhys Thomspon, and Clare Watt

Earth’s radiation belts are a hazardous environment containing trapped charged particles. Radial diffusion is one of the major processes driving radiation belt physics, accounting for energisation, transport and loss of electrons in the outer belt. The outer radiation belt is highly variable in energy and location, resulting in behaviour which is difficult to model accurately.

 

Ensemble modelling is needed to characterise this variability. Ensembles can be constructed by varying physical parameters (capturing the uncertainty in our knowledge across many scales) and considering the spread of the final model outputs. However, it is unclear what proportion of the subsequent variability comes from physics versus the numerical methods used. We investigate the effect of varying initial conditions for typical radial diffusion coefficients.

 

We present two methods of establishing the timescale over which initial conditions affect the subsequent radial diffusion; time to monotonicity (the time taken for the particle distribution to reach a state where radial diffusion effects become uninteresting) and dimensional analysis. Both are needed to capture the processes we are interested in as well as the inherent timescales from diffusion. Our measures are often domain dependent, indicating that the choice of where we perform our radial diffusion simulations is significant.

 

How to cite: Bentley, S., Stout, J., Ratliff, D., Thomspon, R., and Watt, C.: Radial Diffusion Benchmarking: Initial Conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3258, https://doi.org/10.5194/egusphere-egu23-3258, 2023.

EGU23-3517 | ECS | Orals | ST1.4

Cometary Plasma Science - Open questions and implications for heliophysics 

Charlotte Goetz and the Cometary Plasma Science White Paper Team

Comets hold the key to the understanding of our Solar System, its formation and its evolution, and to the fundamental plasma processes at work both in it and beyond it. A comet nucleus emits gas as it is heated by the sunlight. The gas forms the coma, where it is ionised, becomes a plasma, and eventually interacts with the solar wind. Besides these neutral and ionised gases, the coma also contains dust grains, released from the comet nucleus. As a cometary atmosphere develops when the comet travels through the Solar System, large-scale structures, such as the plasma boundaries, develop and disappear, while at planets such large-scale structures are only accessible in their fully grown, quasi-steady state. In situ measurements at comets enable us to learn both how such large-scale structures are formed or reformed and how small-scale processes in the plasma affect the formation and properties of these large scale structures. Furthermore, a comet goes through a wide range of parameter regimes during its life cycle, where either collisional processes, involving neutrals and charged particles, or collisionless processes are at play, and might even compete in complicated transitional regimes. Thus a comet presents a unique opportunity to study this parameter space, from an asteroid-like to a Mars- and Venus-like interaction. The Rosetta mission and previous fast flybys of comets have together made many new discoveries, but the most important breakthroughs in the understanding of cometary plasmas are yet to come. The Comet Interceptor mission will provide a sample of multi-point measurements at a comet, setting the stage for a multi-spacecraft mission to accompany a comet on its journey through the Solar System. We will review the present-day knowledge of cometary plasmas, discuss the many questions that remain unanswered, and outline a multi-spacecraft European Space Agency mission to accompany a comet that will answer these questions by combining both multi-spacecraft observations and a rendezvous mission, and at the same time advance our understanding of fundamental plasma physics and its role in planetary systems.

How to cite: Goetz, C. and the Cometary Plasma Science White Paper Team: Cometary Plasma Science - Open questions and implications for heliophysics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3517, https://doi.org/10.5194/egusphere-egu23-3517, 2023.

EGU23-4065 | Orals | ST1.4

STELLA—Potential European  contributions to a NASA-led interstellar probe 

Robert F. Wimmer-Schweingruber, Nicolas André, Stas Barabash, Pontus C. Brandt, Timothy S. Horbury, Luciano Iess, Benoit Lavraud, Ralph L. McNutt, Jr., Elena A. Provornikova, Eric Quémerais, Robert Wicks, Martin Wieser, and Peter Wurz

Stella is a proposed European contribution to NASA’s Interstellar Probe (ISP), a large-strategic mission candidate. ESA’s call for M-class mission proposals was the best and only currently available option for the European science community to contribute to the astronomically constrained ISP launch window in 2036 – 2037. Traveling with a speed of ~ 7.0 au/year ISP would reach 350 au during its nominal 50-year life-time. The proposed Stella contribution to ISP includes two core and two optional elements for the full complement:

• Core: Provision of European scientific instruments;

• Core: Provision of the European ISP communication system including the spacecraft’s 5-m high gain antenna;

• Full complement: ESA deep space communication facility: an extension of ESA’s DSA with a new antenna array;

• Full complement: Contribution to ISP operations to increase drastically the ISP and European payloads science return.

How to cite: Wimmer-Schweingruber, R. F., André, N., Barabash, S., Brandt, P. C., Horbury, T. S., Iess, L., Lavraud, B., McNutt, Jr., R. L., Provornikova, E. A., Quémerais, E., Wicks, R., Wieser, M., and Wurz, P.: STELLA—Potential European  contributions to a NASA-led interstellar probe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4065, https://doi.org/10.5194/egusphere-egu23-4065, 2023.

Radial diffusion in planetary radiation belts is a dominant transport mechanism resulting in the energisation and loss processes of charged particles by ultra-low frequency (ULF) fluctuations in the Pc4-Pc5 range. The theoretical framework upon which radial diffusion coefficients have been analytically derived in the past 60 years belongs to various types of quasi-linear theories. In quasi-linear theories, the evolution equation for the distribution function experiencing radial diffusion is only valid on slow timescales longer than the characteristic period of the ULF waves and the azimuthal drift period of the particles, ranging from tens of minutes to a few hours for electrons with energies between tens of keV to several hundreds of keV. Therefore, radiation belts’ dynamical processes occurring on fast timescales comparable to ULF wave periods or azimuthal drift periods, such as fast magnetopause losses localised in magnetic local time (MLT), cannot self-consistently be quantified in terms of radial diffusion models. In this communication, we present a new theoretical framework based on drift kinetic (Hazeltine, 1973) to distinguish between the fast and slow response of energetic electrons to ULF waves. We conclude our talk with two examples to demonstrate the benefits of the drift kinetics approach: 1) fast electron losses due to MLT localised compression of the magnetopause, and 2) non-diffusive acceleration associated with symmetric ULF fluctuation.  

How to cite: Osmane, A.: A new theoretical framework to model radial transport of energetic particles by ULF waves in the Earth's magnetosphere., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5242, https://doi.org/10.5194/egusphere-egu23-5242, 2023.

EGU23-5715 | Orals | ST1.4

Plasma-neutral gas interactions in various space environments beyond simplified approximations 

Masatoshi Yamauchi, Johan De Keyser, George Parks, Shin-ichiro Oyama, Peter Wurz, Takumi Abe, Arnaud Beth, Malcolm Dunlop, Pierre Henri, Harald Kucharek, Octav Marghitu, Georgios Nicolaou, Manabu Shimoyama, Joachim Saur, Satoshi Taguchi, Takuo Tsuda, and Bruce Tsurutani

The majority of the atmospheres of solar system bodies are composed of neutral gas, and hence their upper atmosphere are always partially ionized by the solar UV and collisions, allowing a complex nonlinear interaction with interplanetary plasma.  Thus, ion-neutral and electron-neutral interaction plays a key role in this transition regions (ionosphere for planets and moons). However, our current understanding of plasma-neutral gas interactions is very limited due to lack of observations with proper instrumentation and to the difficulty in making laboratory experiments (almost impossible to reproduce the ionosphere with low energy plasma).  Particularly the effect of small amount of neutral species in space above the exobase and the effects of electric charges on neutrals have been underestimated.  

To advance our knowledge of these basic but still poorly understood interactions between plasma and neutral gas at key regions of energy, momentum, and mass exchange between the space and the atmosphere, we evaluate what kind of measurement package is needed for different solar system objects in a cost-effective manner.  We particularly focus on understanding the re-distribution of externally provided energy to the composing species through this interaction.  

The presentation is based on a white paper submitted to ESA's Voyage 2050 (Experimental Astronomy, 2022), and related mission proposals to space agencies.  Here we skip the chemical aspect that is also mentioned in the white paper.

Reference: https://doi.org/10.1007/s10686-022-09846-9

How to cite: Yamauchi, M., De Keyser, J., Parks, G., Oyama, S., Wurz, P., Abe, T., Beth, A., Dunlop, M., Henri, P., Kucharek, H., Marghitu, O., Nicolaou, G., Shimoyama, M., Saur, J., Taguchi, S., Tsuda, T., and Tsurutani, B.: Plasma-neutral gas interactions in various space environments beyond simplified approximations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5715, https://doi.org/10.5194/egusphere-egu23-5715, 2023.

EGU23-5939 | Orals | ST1.4

Plasma-Neutral Interactions in the Lower Thermosphere-Ionosphere: The need for in situ measurements to address outstanding questions 

Theodoros Sarris and the co-authors of the white paper for the decadal survey for solar and space physics 2024-2033

The lower thermosphere-ionosphere (LTI) is a key transition region between the Earth’s neutral atmosphere and plasma-dominated space. Interactions between ions and neutrals maximize within the LTI and in particular at altitudes from 100 to 200 km, which is the least visited region of the near-Earth environment due to enhanced atmospheric drag. The lack of in situ co-temporal and co-spatial measurements of all relevant parameters and their elusiveness to most remote-sensing methods means that the complex interactions between neutral and charged constituents in the LTI remain poorly characterized to this date. This lack of measurements, together with the ambiguity in the quantification of key processes in the 100 to 200 km altitude range, affect current modeling efforts to expand atmospheric models upward to include the LTI and limit current space weather prediction capabilities. In this talk, fundamental science themes in ionosphere-thermosphere physics and related societal and operational needs are outlined; past proposed implementation schemes to sample this transition region are reviewed; and recent efforts by ESA and NASA to highlight outstanding science questions in the LTI and the need for in situ measurements to address them are presented.

How to cite: Sarris, T. and the co-authors of the white paper for the decadal survey for solar and space physics 2024-2033: Plasma-Neutral Interactions in the Lower Thermosphere-Ionosphere: The need for in situ measurements to address outstanding questions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5939, https://doi.org/10.5194/egusphere-egu23-5939, 2023.

EGU23-6626 | ECS | Orals | ST1.4

Global coronal structure and possible new insights in the upcoming perihelia of Parker Solar Probe 

Samuel Badman, Yeimy Rivera, Stuart Bale, and Michael Stevens

 The global structure of the Sun’s extended corona is governed by the physical processes which represent some of the biggest outstanding questions in heliophysics. These include the nature of coronal heating and solar wind acceleration. NASA’s Parker Solar Probe (PSP) offers unique new opportunities to probe this structure directly through its unprecedented orbit which takes it closer to the Sun than any prior spacecraft. As of Spring 2023, PSP has achieved perihelia of 13.3 Rs, but will continue to dive deeper to an eventual closest approach of 9.8Rs at the end of 2024. Already PSP is starting to offer tantalizing glimpses into the sub-alfvenic corona. The most recent orbits exhibit hints of an imminent global plasma regime change on multiple fronts: As well as unambiguous crossings of the Alfven critical surface, PSP sees significant solar wind deceleration, possible global magnetic field reorganization, and proton core temperatures hot enough to be comparable to isothermal solar wind models. In this talk, we will discuss how these exciting initial measurements may become decisive constraints in the latter orbits of the PSP mission. We trace the implications of making such direct measurements of the corona-solar wind transition to the science questions of coronal heating and solar wind acceleration.

How to cite: Badman, S., Rivera, Y., Bale, S., and Stevens, M.: Global coronal structure and possible new insights in the upcoming perihelia of Parker Solar Probe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6626, https://doi.org/10.5194/egusphere-egu23-6626, 2023.

EGU23-6791 | Orals | ST1.4

Physics of plasma–surface–exosphere–dust coupling at the lunar surface for future exploration programmes 

Yoshifumi Futaana and the ESA Topical Team : Physics Of Plasma-Surface-Exosphere-Dust Coupling At The Lunar Surface For Future Exploration Programmes

Exploration of the Moon provides opportunities to investigate the deep space environment upstream of the geospace and the terrestrial magnetosphere and associated space weather phenomena. Moreover, the Moon interaction with the solar wind adds novel, interdisciplinary aspects to fundamental space research: a complex coupling between the solar wind/magnetospheric plasma – energetic particles – exosphere – dust – solid-surface – mini-magnetosphere. As the Moon is the next step in space exploration, characterizing the environment provides vital support to this endeavor. We note that investigations in this area of science are invaluable in providing a characterization of the environment for the needs of human exploration. On the other hand,  the lunar environment is fragile against human activities. For example, the total mass of the lunar atmosphere is of the order of 10 tons. Therefore, the environment will change drastically once human activity starts on the lunar surface. It is significantly essential to characterize the environment before the fragile lunar atmosphere is “contaminated” by human activities at the surface.
With these aspects as a background, we formed an ESA topical team to formulate scientific questions in space plasma physics that can be uniquely investigated on or near the lunar surface. We also derived the required measurements, which can be addressed by lunar missions in the short and long term, including the EL3 (European Logistic Lunar Lander) mission. This presentation introduces the background scientific context and describes the derived scientific concepts. 

How to cite: Futaana, Y. and the ESA Topical Team : Physics Of Plasma-Surface-Exosphere-Dust Coupling At The Lunar Surface For Future Exploration Programmes: Physics of plasma–surface–exosphere–dust coupling at the lunar surface for future exploration programmes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6791, https://doi.org/10.5194/egusphere-egu23-6791, 2023.

EGU23-7030 | Posters virtual | ST1.4

Measuring the Net Charge Density of Space Plasmas 

Chao Shen

Space plasmas are composed of charged particles that play a key role in electromagnetic dynamics. However, to date, there has been no direct measurement of the distribution of such charges in space. In this study, three schemes for measuring charge densities in space are presented. The first scheme is based on electric field measurements by multiple spacecraft. This method is applied to deduce the charge density distribution within Earth’s magnetopause boundary layer using Magnetospheric MultiScale constellation (MMS) 4-point measurements, and indicates the existence of a charge separation there. The second and third schemes proposed are both based on electric potential measurements from multiple electric probes. The second scheme, which requires 10 or more electric potential probes, can yield the net charge density to first-order accuracy, while the third scheme, which makes use of seven to eight specifically distributed probes, can give the net charge density with second-order accuracy. The feasibility, reliability, and accuracy of these three schemes are successfully verified for a charged-ball model. These charge density measurement schemes could potentially be applied in both space exploration and ground-based laboratory experiments.

 

How to cite: Shen, C.: Measuring the Net Charge Density of Space Plasmas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7030, https://doi.org/10.5194/egusphere-egu23-7030, 2023.

EGU23-7436 | Posters virtual | ST1.4

Exploring solar-terrestrial interactions via multiple imaging observers 

Graziella Branduardi-Raymont

How does solar wind energy flow through the Earths magnetosphere, how is it converted and distributed? This are the questions we want to address. We need to understand how geomagnetic storms and substorms start and grow, not just as a matter of scientific curiosity, but to address a clear and pressing practical problem: space weather, which can influence the performance and reliability of our technological systems, in space and on the ground, and can endanger human life and health.

Much knowledge has already been acquired over the past decades, particularly by making use of multiple spacecraft measuring conditions in situ, but the infant stage of space weather forecasting demonstrates that we still have a vast amount of learning to do. A novel global approach is now being taken by a number of space imaging missions which are under development and the first tantalising results of their exploration will be available in the next decade. In a White Paper, submitted to ESA in response to the Voyage 2050 Call, we propose the next step in the quest for a complete understanding of how the Sun controls the Earth’s plasma environment: a tomographic imaging approach comprising two spacecraft in highly inclined polar orbits, enabling global imaging of magnetopause and cusps in soft X-rays, of auroral regions in FUV, of plasmasphere and ring current in EUV and ENA (Energetic Neutral Atoms), alongside in situ measurements. Such a mission, encompassing the variety of physical processes determining the conditions of geospace, will be crucial on the way to achieving scientific closure on the question of solar-terrestrial interactions.

The White Paper was published on 16 August 2021 (G. Branduardi-Raymont et al., Experimental Astronomy, https://doi.org/10.1007/s10686-021-09784-y) and full co-author details are at the end of the article.

How to cite: Branduardi-Raymont, G.: Exploring solar-terrestrial interactions via multiple imaging observers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7436, https://doi.org/10.5194/egusphere-egu23-7436, 2023.

EGU23-8410 | Posters virtual | ST1.4

Future Heliospheric System Science Exploration in Japan 

Yoshifumi Saito, Yoshizumi Miyoshi, Kanako Seki, and Shinsuke Imada

Toward the inner Heliospheric system science exploration in the late 2020s, ISAS/JAXA is currently operating the Arase, BepiColombo/Mio, Hinode, and Akatsuki satellites, and Solar-C EUVST is scheduled for launch in the near future. These missions will be linked together with other satellite missions such as Solar-Orbiter, Solar Parker Probe, Cluster, THEMIS, MMS etc. to realize exploration of the inner Heliosphere with unprecedented scale.

In the early 2030s, Japanese Solar Terrestrial Physics group is considering the FACTORS formation-flight satellite mission in order to reveal the energy coupling mechanisms and mass transport between the space and Earth’s atmosphere. In the late 2030s, another formation-flight magnetospheric satellite mission the science target of which includes understanding the cross-scale / cross-region coupling is also under consideration hopefully on orbit at the same time with European future mission Plasma Observatory. These future missions will closely collaborate with NASA’s future GDC and Magnetospheric Constellation missions.

The future Heliospheric system science exploration will be conducted by multiple satellite missions further expanding their observation area while improving the quality of each individual satellite mission. Japanese Solar Terrestrial Physics group will conduct in-situ observation of space plasmas with MMX (Martian Moons Exploration) and MIM(Mars Ice Mapper) in the Martian system and with JUICE (Jupiter Icy Moons Explorer) in the Jovian system. Collaboration between Japanese Solar Physics and Solar Terrestrial Physics groups for considering the future out-of-ecliptic-plane mission is also about to start.

In order to realize the future Heliospheric system science exploration, significant technological development is mandatory. Current status of the technological development in Japan for enabling the future Heliospheric system science exploration will also be presented.

How to cite: Saito, Y., Miyoshi, Y., Seki, K., and Imada, S.: Future Heliospheric System Science Exploration in Japan, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8410, https://doi.org/10.5194/egusphere-egu23-8410, 2023.

EGU23-8879 | Posters on site | ST1.4

On the Contribution of Coronal Mass Ejections to the Heliospheric Magnetic Flux Budget on Different Time Scales 

Reka Winslow, Camilla Scolini, Noé Lugaz, Nathan Schwadron, and Antoinette Galvin

Coronal mass ejections (CMEs) contribute closed magnetic flux to the heliosphere while they are connected at both ends to the Sun and play a key role in adding magnetic flux to the heliosphere. Here, we discuss an outstanding question in heliophysics: how the type of magnetic reconnection that opens CME field lines in the inner heliosphere, i.e. interchange (IC) reconnection (below the Alfvén surface) and/or interplanetary (IP) reconnection (above the Alfvén surface), determines the length of time CMEs contribute to the heliospheric flux budget. Although IP reconnection does not alter the total amount of magnetic flux in the heliosphere, it matters in this context because it prevents the efficient opening of CME closed magnetic flux through IC reconnection, thereby prolonging the length of time that CMEs contribute closed magnetic flux to the heliosphere. We suggest that there is a varying timescale of contribution of individual CMEs to the heliospheric flux budget, with some CMEs contributing for considerably longer than others, depending on their interactions in IP space (i.e., depending on the fraction of the CME magnetic field lines opened up through IP reconnection vs. IC reconnection, or both). Such a distinction has not been taken into account in past studies that estimate the CME flux opening timescale. We outline key criteria to aid in distinguishing IC reconnection from IP reconnection based on in situ spacecraft data and highlight these through two example events. Studying the manner in which CMEs reconnect and open in the inner heliosphere has implications for a broad range of solar and heliospheric physics research areas and yields important insights not only into CMEs' role in the heliospheric flux budget but also the evolution of CME complexity, connectivity, and topology.

How to cite: Winslow, R., Scolini, C., Lugaz, N., Schwadron, N., and Galvin, A.: On the Contribution of Coronal Mass Ejections to the Heliospheric Magnetic Flux Budget on Different Time Scales, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8879, https://doi.org/10.5194/egusphere-egu23-8879, 2023.

EGU23-9043 | Posters on site | ST1.4

Plasma Observatory ESA M7 candidate mission: unveiling plasma energization and energy transport through multiscale observations 

Maria Federica Marcucci, Alessandro Retinò, Malcolm Dunlop, Colin Forsyth, Yuri Khotyaintsev, Olivier Le Contel, Ian Mann, Rumi Nakamura, Minna Palmroth, Ferdinand Plaschke, Jan Soucek, Masatoshi Yamauchi, Andris Vaivads, and Francesco Valentini and the Plasma Observatory Team

The Earth's Magnetospheric System is the complex and highly dynamic environment in near-Earth space where plasma gets actively energized and transport of large amounts of energy occurs, due to the interaction of the solar wind with the Earth's magnetic field. Understanding plasma energization and energy transport is an open challenge of space plasma physics, with important implications for space weather science as well as for the understanding of distant astrophysical plasmas. Plasma energization and energy transport are related to fundamental processes such as shocks, magnetic reconnection, turbulence and waves, plasma jets and instabilities, which are at the core of the current space plasma physics research. ESA/Cluster and NASA/MMS four-point constellations, as well as the large-scale multipoint mission NASA/THEMIS, have greatly improved over the last two decades our understanding of plasma processes at individual scales compared to earlier single-point measurements. Despite the large amount of available observations, we still do not fully understand the physical mechanisms which give rise to plasma energization and energy transport. The reason is that the fundamental physical processes governing plasma energization and energy transport operate across multiple scales ranging from the large fluid to the smaller kinetic scales. Here we present the Plasma Observatory (PO) multiscale mission concept which is tailored to study plasma energization and energy transport within the Earth's Magnetospheric System. PO baseline is comprised of one mothercraft (MSC) and six identical smallsat daughtercraft (DSC) in an HEO 8 RE X 18 RE orbit, covering all the key regions of the Magnetospheric System where strong energization and transport occur: the foreshock, bow shock, magnetosheath, magnetopause, magnetotail current sheet, and the transition region. MSC payload provides a complete characterization of electromagnetic fields and plasma particles in a single point with time resolution sufficient to resolve kinetic physics at sub-ion scales. The DSCs have identical payload which is much simpler than on the MSC, yet giving a full characterization of the plasma at the ion and fluid scales. Going beyond Cluster, THEMIS and MMS, PO will permit us to resolve for the first time the coupling between ion and fluid scales as well as the non-planarity and non-stationarity of plasma structures at those scales.  PO is one of the five ESA M7 candidates to be launched around 2037 and is currently undergoing a competitive Phase 0 at ESA for further downselection to Phase A at the end of 2023.

How to cite: Marcucci, M. F., Retinò, A., Dunlop, M., Forsyth, C., Khotyaintsev, Y., Le Contel, O., Mann, I., Nakamura, R., Palmroth, M., Plaschke, F., Soucek, J., Yamauchi, M., Vaivads, A., and Valentini, F. and the Plasma Observatory Team: Plasma Observatory ESA M7 candidate mission: unveiling plasma energization and energy transport through multiscale observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9043, https://doi.org/10.5194/egusphere-egu23-9043, 2023.

EGU23-9223 | Orals | ST1.4

The ESA Heliophysics Working Group: building cross-discipline bridges to better serve the European Heliophysics  community 

Matthew Taylor, Piers Jiggins, Juha-Pekka Luntama, Astrid Orr, and Anja Strømme

Heliophysics, the science of understanding the Sun and its interaction with the Earth and the solar system, has a large and active international community, with significant expertise and heritage in the European Space Agency and Europe. Several ESA directorates have activities directly connected with this topic, including ongoing and/ or planned missions and instrumentation, comprising a ESA Heliophysics observatory or more musically, a Heliophysics Orchestra. More specifically in ESA: The Directorate of Science with mission such as Ulysses, SOHO, Cluster, Solar Orbiter, SMILE etc, as well as hosting the Heliophysics archive; The Directorate of Earth Observation with Swarm and other Earth Explorer missions, as well as the ongoing ESA-NASA Lower Thermosphere-Ionosphere Science Working Group (EN-LoTIS-WG); The Directorate of Operations with the Vigil mission, the Distributed Space Weather Sensor System (D3S) and the Space Weather Service Network; The Directorate of Human and Robotic Exploration with many ISS and LOP-Gateway payloads and the Directorate of Technology, Engineering Quality with expertise in developing instrumentation and models for measuring and simulating environments throughout the heliosphere.

An ESA Heliophysics Working group has been appointed by several ESA Directors, under the direction of the ESA Director General, to work on optimizing synergies across directorates, and to act as a focus for discussion, inside ESA, of the scientific interests of the Heliophysics community, including the European ground-based community and data archiving activities. 

How to cite: Taylor, M., Jiggins, P., Luntama, J.-P., Orr, A., and Strømme, A.: The ESA Heliophysics Working Group: building cross-discipline bridges to better serve the European Heliophysics  community, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9223, https://doi.org/10.5194/egusphere-egu23-9223, 2023.

EGU23-9239 | Orals | ST1.4

ISTPNext and the ITM Great Observatory: The need for international coordination in Heliophysics 

Emil Kepko and the COSPAR Task Group on Establishing an International Geospace Systems Program

Heliophysics is the study of the Sun and its effects throughout the solar system. It covers an incredible range of scales, from plasma physics at the electron scale to the boundary that separates our solar system from interstellar space. It also includes a diverse array of sub disciplines and expertise, with measurements spanning in situ particles and fields from the ionosphere out to the Sun’s corona, to remote sensing of the Sun, heliosphere, and near-Earth environment at multiple wavelengths and in energetic neutral atom observations. Many of the biggest unanswered science questions that remain across Heliophysics center around the interconnectivity of the different physical systems that comprise the Heliosphere, and the role of mesoscale dynamics in modulating, regulating, and controlling that interconnected behavior. These are complex, yet ultimately fundamental questions of how the Sun-Heliosphere and Geospace interact, and answers are needed to more accurately predict and model space weather impacts on and around Earth, the moon, and Mars. To answer these long-standing questions on the Sun-Heliosphere and Geospace as system-of-systems, we believe that Heliophysics requires a coordinated, deliberate, worldwide scientific effort. We suggest that the worldwide Heliophysics discipline should embark on a grand program to study these system-of-systems holistically, with coordinated, multipoint measurements, with particular emphasis on resolving mesoscale dynamics, and a whole-of-science approach that includes ground-based measurements and advanced numerical modeling. Without such a unified, next generation ISTP-type program, these questions will remain largely unanswered. In this paper we lay out the case for such an approach, and discuss how the ITM community is using the upcoming NASA GDC mission as a cornerstone to develop the ITM Great Observatory, a grass-roots, holistic approach modeled after ISTP to study the ITM system.

How to cite: Kepko, E. and the COSPAR Task Group on Establishing an International Geospace Systems Program: ISTPNext and the ITM Great Observatory: The need for international coordination in Heliophysics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9239, https://doi.org/10.5194/egusphere-egu23-9239, 2023.

EGU23-9872 | Orals | ST1.4

Our Heliosphere in the Very Local Interstellar Medium: Exploration by New Horizons, Voyager, IBEX, IMAP and a Future Interstellar Probe 

Pontus Brandt, Alan Stern, Linda Spilker, Heather Elliott, Matt Hill, Peter Kollmann, Ralph McNutt, Parisa Mostafavi, Dave McComas, Randy Gladstone, Mihaly Horanyi, Andrew Poppe, Elena Provornikova, Jeff Linsky, Seth Redfield, Tod Lauer, Kelsi Singer, John Spencer, Anne Verbiscer, and Merav Opher

Our solar system has evolved through accretion of dust and gas as the Sun and its protective magnetic bubble – “the heliosphere” - have plowed through interstellar space on its journey through the galaxy. Over the course of its evolution, the solar system has encountered dramatically different interstellar properties resulting in a severely compressed heliosphere with periods of full exposures of interstellar gas, plasma, dust and galactic cosmic rays (GCRs) that all have helped shaped the system we live in today. Our current knowledge lacks the direct measurements necessary to understand how our star upholds its vast heliosphere and its potentially game-changing role in the evolution of our galactic home.

Voyager 1 and 2 are now in the Very Local Interstellar Medium (VLISM), where they are expected to operate until the mid-2030’s having uncovered many unexpected discoveries and mysteries. After its paradigm-shifting discoveries at Pluto and Arrokoth, New Horizons is currently the only spacecraft in the outer heliosphere and is following the same heliospheric longitude as Voyager 2, but in the ecliptic plane – a trajectory that intersects the IBEX ribbon. It is projected to operate across the heliospheric termination shock and possible the heliopause with new measurements that will shed light on many of the mysteries of our heliosphere. Now passing 55 au, New Horizons is uniquely positioned to investigate the evolution of the solar wind, energetic particles, GCRs, and, in particular interstellar Pick-Up Ions (PUIs) that Voyager was not equipped to measure, to help constrain the structure and dynamics of the heliosphere. Observations of GCRs offers an opportunity to understand how these scatter strongly in the wavy structure of the “ballerina skirt” of the solar magnetic field leading to the strong modulation as part of the overall heliospheric shielding.

As New Horizons continues to travel outward, dust measurements may reveal an interstellar component that will provide the strongest constraint to date on how interstellar dust grains interact with the heliosphere. Now beyond the infrared and UV haze of the circumsolar dust and hydrogen gas, the Alice UV camera holds promise to search for signatures of the hydrogen wall and perhaps even signatures of our neighboring interstellar clouds.

New Horizons continues to break new ground in understanding the formation of our solar system by revealing the properties of multiple distant Kuiper Belt Objects and provide critical constraints on the structure of the Sun’s enormous dust disk. Because of its distant position, New Horizons is also providing the unprecedented estimates of the cosmic background.

In this presentation we provide an overview of New Horizons’ heliophysics observations in the context of the exploration by Voyager, IBEX, and IMAP. We conclude by providing a status of the future Interstellar Probe mission concept that is now under consideration in the Solar and Space Physics Decadal Survey.

How to cite: Brandt, P., Stern, A., Spilker, L., Elliott, H., Hill, M., Kollmann, P., McNutt, R., Mostafavi, P., McComas, D., Gladstone, R., Horanyi, M., Poppe, A., Provornikova, E., Linsky, J., Redfield, S., Lauer, T., Singer, K., Spencer, J., Verbiscer, A., and Opher, M.: Our Heliosphere in the Very Local Interstellar Medium: Exploration by New Horizons, Voyager, IBEX, IMAP and a Future Interstellar Probe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9872, https://doi.org/10.5194/egusphere-egu23-9872, 2023.

EGU23-10279 | ECS | Posters on site | ST1.4

Energetic Particles in the Outer Heliosphere 

Parisa Mostafavi, Matthew Hill, Peter Kollmann, Pontus Brandt, Ralph McNutt, Alan Stern, Bishwas Shrestha, Fran Bagenal, Kelsi Singer, Anne Verbiscer, and John Spencer

Nonthermal energetic pickup ions (PUIs), created in the heliosphere by charge exchange between solar wind ions and interstellar neutral atoms, play an essential role in understanding solar wind evolution in the outer heliosphere and the structure and dynamics of the global heliosphere. New Horizons spacecraft, launched in 2006, is now located at about 55 au from the Sun, exploring the outer heliosphere, and is the only spacecraft equipped with proper instruments to measure nonthermal energetic pickup ions (PUIs) in the outer heliosphere for the first time. Its observations showed that energetic PUIs dominate the internal pressure of the outer heliosphere, with PUI pressures larger than the thermal solar wind and magnetic pressures outside ~ 20 au. At these distances, PUIs contribute substantially to heating and slowing down the solar wind. Moreover, New Horizons observations showed that PUIs mediate shock waves in the outer heliosphere. Here, we give an overview of the energetic particles in the outer heliosphere and their effect on shocks. We present the in situ observations of the hydrogen and Helium PUIs made by New Horizons' SWAP and PEPSSI instruments. Finally, we present some of the most important open questions related to the outer heliosphere that future studies and space missions should address.

How to cite: Mostafavi, P., Hill, M., Kollmann, P., Brandt, P., McNutt, R., Stern, A., Shrestha, B., Bagenal, F., Singer, K., Verbiscer, A., and Spencer, J.: Energetic Particles in the Outer Heliosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10279, https://doi.org/10.5194/egusphere-egu23-10279, 2023.

In the 2020s we are entering a golden age of inner heliosphere science. International Mercury exploration mission BepiColombo was launched in 2018 and will arrive at Mercury in 2025. During the interplanetary cruise phase, BepiColombo will range from 1.2 AU to 0.3 AU, and will stay in the inner heliosphere for long time. BepiColombo started its science observations during the interplanetary cruise phase in 2020. The initial results showed its enough performance to observe solar wind electrons, IMF, and solar energetic particles (SEPs) even in the composite spacecraft configuration. Especially in 2021 two spacecraft of BepiColombo, Mercury Planetary Orbiter (MPO) and Mercury Magnetosphere Orbiter (Mio), successfully detected many SEP events. BepiColombo can contribute to leading and expanding the heliospheric system science. In addition to BepiColombo, NASA’s Parker Solar Probe and ESA’s Solar Orbiter are also exploring the inner heliosphere. Coordinated observations between these multi spacecraft have been planned and performed. In March 2021, we also coordinated a joint observation campaign of the solar corona and solar wind with BepiColombo, Akatsuki, and Hinode. These coordinated observations/analysis with multi spacecraft, ground-based observations, and numerical simulations can give us great opportunities to address outstanding questions in heliophysics. Here we Here we present the overview and updated status of BepiColombo and the coordinated science observations.

How to cite: Murakami, G. and Benkhoff, J.: Coordinated observations for inner heliospheric science: contribution by the BepiColombo mission, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11768, https://doi.org/10.5194/egusphere-egu23-11768, 2023.

EGU23-11849 | Posters on site | ST1.4

3D evolution of localized plasma flow and its interaction with ambient field 

Rumi Nakamura, Yoshizumi Miyoshi, and Evgeny Panov

A major part of the transport of the magnetic flux and energy in the midtail and the near-Earth tail region is accomplished by local fast plasma jets, called bursty bulk flows (BBF) or flow bursts.  The interaction between BBF and ambient field plays an important role in the complex chain of solar wind-magnetosphere-ionosphere coupling processes. Furthermore, near-Earth flow braking/bouncing processes and associated magnetic and pressure disturbances in the transition region of the magnetic field configuration from tail-like to dipolar field  lead to complex localized current sheet restructuring. Associated energetic particle injection further effects the inner magnetosphere bringing in the source population of the plasma waves that cause electron accelerations as well as seed populations of the radiation belts.

 

In this presentation we stress the importance of observations of BBF and dipolarization by covering extensive region, both near the equator and off-equator simultaneously, for understanding the energy transport processes by including both the field-aligned and perpendicular evolution of the flux tube.  By showing several examples of observations with fortuitous multi-spacecraft configuration, 3D nature of the interaction between BBF and ambient plasma will be discussed. 

 

 

How to cite: Nakamura, R., Miyoshi, Y., and Panov, E.: 3D evolution of localized plasma flow and its interaction with ambient field, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11849, https://doi.org/10.5194/egusphere-egu23-11849, 2023.

EGU23-12289 | ECS | Orals | ST1.4

Citizen science and the exploration of solar data 

Sophie Musset, Lindsay Glesener, Ramana Sankar, Lucy Fortson, Paloma Jol, Kekoa Lasko, Yixian Zhang, Navdeep Panesar, Gregory Fleishman, Mariana Jeunon, Neal Hurlburt, and Yuping Zheng

Citizen science provides a way to analyze large and complex data sets, complementary to contemporary tools such as machine learning. Indeed, while trained algorithms excel in the task they are trained for, humans can spot outliers and make serendipitous discoveries. With recent and new instruments, we are able to observe the Sun and the heliosphere at high cadence and high resolution, providing large amounts of data, revealing complexity in the observed features, and leading to the discovery of new features on small scales. We will present how citizen science, while still under-utilized in solar and heliospheric physics, is particularly adapted to explore, and analyze solar data sets. The “Solar Jet Hunter”, a citizen science project launched one year ago to build a catalog of coronal jets, will be presented as an example, and other science cases for which citizen science is the most adequate tool will be highlighted. Finally, the opportunities raised by citizen science to create strong relationships between academia and society will be discussed.

How to cite: Musset, S., Glesener, L., Sankar, R., Fortson, L., Jol, P., Lasko, K., Zhang, Y., Panesar, N., Fleishman, G., Jeunon, M., Hurlburt, N., and Zheng, Y.: Citizen science and the exploration of solar data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12289, https://doi.org/10.5194/egusphere-egu23-12289, 2023.

The “Mars Magnetosphere ATmosphere Ionosphere and Space-weather SciencE (M-MATISSE)” mission is an ESA Medium class (M7) candidate currently in Phase 0 study by ESA. M-MATISSE’s main scientific goal is to unravel the complex and dynamic couplings of the Martian magnetosphere, ionosphere and thermosphere (MIT coupling) with relation to the Solar Wind (i.e. space weather) and the lower atmosphere. It will provide the first global characterisation of the dynamics of the Martian system at all altitudes, to understand how the atmosphere dissipates the incoming energy from the solar wind, including radiation, as well as how different surface processes are affected by Space Weather activity.

M-MATISSE consists of two orbiters with focused, tailored, high-heritage payloads to observe the plasma environment from the surface to space through coordinated simultaneous observations. It will utilize a unique 3-vantage point observational perspective, with the combination of in-situ measurements by both orbiters and remote observations of the lower atmosphere and ionosphere by radio crosstalk between them.

M-MATISSE is the product of a large organized and experienced international consortium. It has the unique capability to track solar perturbations from the Solar Wind down to the surface, being the first mission fully dedicated to understand planetary space weather at Mars. It will revolutionize our understanding and ability to forecast potential global hazard situations at Mars, an essential precursor to any future robotic & human exploration.

How to cite: Sanchez-Cano, B. and the the M-MATISSE team: The M-MATISSE mission: Mars Magnetosphere ATmosphere Ionosphere and Space weather SciencEAn ESA Medium class (M7) candidate, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13687, https://doi.org/10.5194/egusphere-egu23-13687, 2023.

ESA F-Class missions offer a new opportunity to do space science with smaller, cheaper spacecraft. The mission format presents a tough challenge for plasma physics missions, can we make simple, small and cost-effective spacecraft for a topic that will make breakthrough discoveries? This presentation will discuss the past two proposals of the Debye mission, the lessons learned and the challenges ahead to make a similar mission feasible. Debye addresses a grand-challenge problem at the forefront of physics: to understand how energy is transported and transformed in plasmas. The smallest characteristic scales, at which electron dynamics determines the behaviour of energy, are the next frontier in space and astrophysical plasma research. Debye will be the first electron-astrophysics mission. Electron-kinetic processes operate at very small scales (< 10 km) but define the behaviour of the plasma at system-size scales. Debye will use the solar wind as a natural plasma laboratory to measure these electron-scale processes. Understanding the heating, acceleration, thermalisation, and heat flux of electrons is fundamental to our understanding of the dynamics and thermodynamics of plasmas throughout the Universe and thus to the entire field of astrophysics. Debye will answer the fundamental science question "How are electrons heated in astrophysical plasmas?" The mission will make the highest-resolution measurements of electrons ever made in space in terms of energy, angle, time, and space, coupled with two-point high-cadence field measurements to identify the plasma fluctuations responsible for electron energisation. This mission concept will provide ground-breaking and transformative physics results since the combination of rapid particle and field measurements over distances of less than 10 km is completely unprecedented. We believe Debye is a fast, feasible, and focussed mission, tailored to achieve these science objectives, but there are some technical challenges that are assessed to be problematic, how can we address data transmission, formation flying, the cost of multi-item payloads and multi-spacecraft missions?

How to cite: Wicks, R. and Verscharen, D.: Electron-astrophysics in the solar wind: plasma physics at F-Class, lessons learned and things to do., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13772, https://doi.org/10.5194/egusphere-egu23-13772, 2023.

EGU23-14278 | ECS | Posters on site | ST1.4

Sub-Alfvénic solar wind streams near the earth: characteristics and their origin 

Rong Lin, Jiansen He, and Chuanpeng Hou

The PSP observation of a long-lived sub-Alfvénic solar wind, along with its magnetic-dominant character, marks a milestone that a human spacecraft has entered the solar corona for the first time (Kasper et al. 2021 PRL). In fact, sub-Alfvénic solar wind streams have also been observed multiple times near the earth by WIND spacecraft. What are the difference and possible connections between the sub-Alfvénic streams very close to the sun and the sub-Alfvénic streams 1 au from the sun? What process generates and sustains the near-earth sub-Alfvénic streams as they propagate outwards? Why the yearly occurrence frequency of them strongly correlates with solar activity? We study several sub-Alfvénic streams, which can be categorized into two groups: sub-Alfvénic background solar wind and sub-Alfvénic ICMEs. In-situ observations, remote observations, and connecting tools are used in our study. We find the sub-Alfvénic background streams are magnetic enhancements embedded in rarefactions. Their origin can be the boundary of the expanding coronal holes and shrinking active regions. A sub-Alfvénic ICME is generally a low-density part of the whole ICME, whose solar origin tends to be elusive in the coronagraph but still geomagnetically effective because of the ICME magnetic field.

How to cite: Lin, R., He, J., and Hou, C.: Sub-Alfvénic solar wind streams near the earth: characteristics and their origin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14278, https://doi.org/10.5194/egusphere-egu23-14278, 2023.

EGU23-15055 | Posters virtual | ST1.4

Cool Multiphase Plasma in Hot Environments 

Patrick Antolin and Clara Froment

Cool plasmas (≈ 104 K) embedded in a larger, much hotter (>106 K) medium are ubiquitous in different astrophysical systems such as solar & stellar coronae, the circumgalactic (CGM), interstellar (ISM) and intra-cluster (ICM) media. The role of these multiphase plasmas has been highlighted in mass-energy cycles at all such scales, from thermal non-equilibrium (TNE) cycles in the solar atmosphere to precipitation-regulated feedback cycles that drive star and galaxy formation. The properties of the cool plasmas across these multiple scales is strikingly similar, intimately linked to the yet unclear but fundamental mechanisms of coronal and ICM heating and instabilities of thermal or other nature. The solar corona constitutes a formidable and unique astrophysics laboratory where we can spatially and temporally resolve the physics of such multiphase plasma. The multi-faceted and measured response of the solar atmosphere to the heating is exemplified by TNE cycles that manifest through EUV intensity pulsations and through the generation of cool coronal rain and prominences whose mysterious properties are like that of multiphase filamentary structure in the ISM and ICM or to molecular loops in the Galactic centre. Coronal rain also occurs across a wide energetic scale extending to flares, whose features seem recurrent in active stars but remains poorly investigated due to lack of multi-temperature coverage at appropriate resolution. The formation and stability-loss of prominences is of major importance to space weather and their ‘slingshot’ counterparts provide unique diagnostic capabilities to the wind mass-loss rate. These exciting new cross-disciplinary possibilities are part of a Heliophysics Decadal Survey white paper and call for a high-resolution multi-wavelength imaging and spectroscopic solar instrument able to capture the multithermal, dynamic and pervasive nature of the multiphase plasma in the hot solar corona.

How to cite: Antolin, P. and Froment, C.: Cool Multiphase Plasma in Hot Environments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15055, https://doi.org/10.5194/egusphere-egu23-15055, 2023.

EGU23-15289 | Posters virtual | ST1.4

Space Weather with Radio Telescopes in Australia 

Mark Cheung, Ron Ekers, John Morgan, Rajan Chhetri, Angelica Waszewski, George Hobbs, Dilpreet Kaur, Andrew Zic, Ramesh Bhat, and Meng Jin

CSIRO, Australia's national science agency, operates a number of world-class radio astronomy observatories that are collectively known as the Australia Telescope National Facility (ATNF). The facility offers a powerful view of the southern hemisphere radio spectrum and supports world-leading research by Australian and international astronomers. Decades after the Culgoora Radioheliograph made fundamental discoveries about solar radio bursts, a new generation of radio telescopes in Australia are providing unique measurement capabilities to address outstanding questions in Heliophysics. Inyarrimanha Ilgari Bundara (“Sharing the Sky and Stars”), the CSIRO Murchison Radio-astronomy Observatory in Western Australia, is home to the Murchison Widefield Array (operated by a consortium led by Curtin University), the Australian Square Kilometre Array Pathfinder (ASKAP), and the future home of the Square Kilometre Array (SKA)-Low Telescope. Interplanetary scintillation (IPS) measurements by these radio telescope arrays will provide important observational constraints of the solar wind and interplanetary coronal mass ejections (ICMEs). This is enabled by simultaneous detections of a high density of scintillating sources over a wide field of view. Complementarily, Parkes Radio Telescope observations towards pulsars may provide density and magnetic field diagnostics of the corona and solar wind. In addition, radio observations toward exoplanet host stars give important constraints on the habitability of exoplanets. In this presentation, we will introduce the facilities, relevant radio astronomical diagnostics, early results, and plans for using the observations for data assimilation. 

How to cite: Cheung, M., Ekers, R., Morgan, J., Chhetri, R., Waszewski, A., Hobbs, G., Kaur, D., Zic, A., Bhat, R., and Jin, M.: Space Weather with Radio Telescopes in Australia, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15289, https://doi.org/10.5194/egusphere-egu23-15289, 2023.

EGU23-16422 | Posters virtual | ST1.4

Venus Dynamics Tracer (VdT) - a mission dedicated for in-situ measurements of the Venus atmosphere. 

Gabriella Stenberg Wieser, Masatoshi Yamauchi, and Moa Persson

Recent Venus missions (Venus Express and Akatsuki) provided a large-scale view of Venus atmosphere and discovered new phenomena, such as high-altitude extension of the mountain wave to the cloud layer and a dawn-dusk asymmetry in the ionospheric motion.  The superrotation of the cloud layer is assumed to be driven by the thermal tide but its relation to any meridional convection or waves is still unknown.  The key to understand all these phenomena is to determine the multi-step re-distribution of the absorbed solar radiation to other forms of energy: (1) internal energy; including temperature, latent heat, and chemical energy (2) kinetic energy both in large scale flows/waves and in minor deviations of convection motions, (3) electric energy including ionization.

To understand how the motion of Venus atmosphere is driven by the energy originating from the absorption of solar radiation, we proposed Venus Dynamics Tracer (VdT), a mission for in-situ measurements, as a response to the ESA call for new M-class missions.  Specific targets were two major energy absorption regions: the cloud layer and the ionized upper atmosphere. The scientific goals were to investigate (a) the roles of the vertical and meridional circulation in maintaining major atmospheric dynamics near the cloud layer where visible light is absorbed and drives the vertical motions of the air, and to understand the (b) global dynamics of ions and neutrals in the upper atmosphere where EUV is absorbed both by neutrals and ions and where energy and momentum are transferred between them. 

For the first target, multiple-balloons are deployed for in situ observations with supporting camera/s on an orbiter giving global context. For the second target, the motions of ions and neutrals are directly measured.  This presentation discusses required measurements to answer the scientific goals.  

How to cite: Stenberg Wieser, G., Yamauchi, M., and Persson, M.: Venus Dynamics Tracer (VdT) - a mission dedicated for in-situ measurements of the Venus atmosphere., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16422, https://doi.org/10.5194/egusphere-egu23-16422, 2023.

EGU23-16967 | Posters on site | ST1.4

A new approach to modeling galactic cosmic rays in the heliosphere using arbitrary data driven MHD backgrounds 

Vladimir Florinski, Juan Alonso Guzman, Merav Opher, and Keyvan Ghanbari

The Voyager space probes provided us with a global perspective on galactic cosmic ray transport through the heliosphere at low to moderate heliographic latitudes, as well as their behavior at the boundary with the very local interstellar medium (VLISM). There remain, however, multiple interesting region the Voyagers have not visited, including high latitudes and the distant flanks of the heliopause where long-term trapping of charged particles is though to take place. We attempt to fill the gaps in our understanding of the distant heliosphere using computer simulations. The Space Plasma and Energetic Charged particle TRansport on Unstructured Meshes (SPECTRUM) code is a versatile software platform to perform tracing of particle trajectories using multiple physics models and internal or externally provided MHD background data. We apply the model to the problem of galactic cosmic ray transport in the outer heliosphere and the surrounding very local interstellar medium (VLISM) using the MHD background provided on a adaptive block mesh from the Space Weather Modeling Framework (SWMF). We compare the guiding center and nearly isotropic (Parker) physics models and elucidate the role of perpendicular diffusion in cosmic-ray penetration through the heliospheric boundary.

How to cite: Florinski, V., Alonso Guzman, J., Opher, M., and Ghanbari, K.: A new approach to modeling galactic cosmic rays in the heliosphere using arbitrary data driven MHD backgrounds, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16967, https://doi.org/10.5194/egusphere-egu23-16967, 2023.

EGU23-17230 | Orals | ST1.4

The Firefly Constellation: The Need for a Wholistic View of the Sun and its Environment 

Nour E. Raouafi and the The Firefly Constellation Team

Firefly is an innovative mission concept study for the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033 to fill long-standing knowledge gaps in Heliophysics. A constellation of spacecraft will provide both remote sensing and in situ observations of the Sun and heliosphere from a whole 4π-steradian field of view. The concept implements a holistic observational philosophy that extends from the Sun’s interior, to the photosphere, through the corona, and into the solar wind simultaneously with multiple spacecraft at multiple vantage points optimized for continual global coverage over much of a solar cycle. The mission constellation includes two spacecraft in the ecliptic and two flying as high as ~70º solar latitude. The ecliptic spacecraft will orbit the Sun at fixed angular distances of ±120º from the Earth. Firefly will provide new insights into the fundamental processes that shape the whole heliosphere. The overarching goals of the Firefly concept are to understand the global structure and dynamics of the Sun’s interior, the generation of solar magnetic fields, the origin of the solar cycle, the causes of solar activity, and the structure and dynamics of the corona as it creates the heliosphere. We will provide an overview of the Firefly mission science and architecture and how it will revolutionize our understanding of long-standing heliospheric phenomena such as the solar dynamo, solar cycle, magnetic fields, solar activity, space weather, the solar wind, and energetic particles

How to cite: Raouafi, N. E. and the The Firefly Constellation Team: The Firefly Constellation: The Need for a Wholistic View of the Sun and its Environment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17230, https://doi.org/10.5194/egusphere-egu23-17230, 2023.

EGU23-4478 | Posters on site | ST1.5

The deep space environment simulation vacuum chamber and large radiometry calibration facilities at Shenzhen University 

Ping Zhu, Huizeng Liu, Mi Song, Shaopeng Huang, and Qingquan Li

The space environment simulation facilities are the key to any successful space experiments and missions. To characterize and validate the optical space instrument, Shenzhen university is started to design a large vacuum chamber with various integrated standard radiation sources, covering a wavelength range from UV to near-infrared. The large radiometry calibration facilities (LRCF) will be traced to standard scale factors such as those maintained by the World Radiation Center at the Physikalisch Meteorologisches Observatorium Davos, Switzerland. In this presentation, we will introduce the LRCF and the broadband radiometer developed for the moon-based earth observation system and how to use the LRCF to characterize the radiometer.

How to cite: Zhu, P., Liu, H., Song, M., Huang, S., and Li, Q.: The deep space environment simulation vacuum chamber and large radiometry calibration facilities at Shenzhen University, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4478, https://doi.org/10.5194/egusphere-egu23-4478, 2023.

Earth Radiation Budget (ERB) measurement is one of the main missions of Chinese second generation of polar orbiting meteorological satellites ---FengYun-3 (FY-3) series. There are two instruments, the Solar Irradiance Monitor(SIM) and the Earth Radiation Budget (ERB), on board FY-3 satellite to observe the earth incoming and reflected solar radiance and the emitted radiance.  The ERMs on FY-3/A/B/C observe the Earth atmosphere within a narrow scanning field of view (NFOV)and a wide non-scanning field of view (WFOV). For each field of view, the measurements are made from two broadband channels: a total waveband channel covering 0.2 – 50 μm and a Short Wave (SW) band covering 0.2 - 4.3 μm. Because the sudden degradation happened that the SW channel of NFOV has stopped working after 20 months for FY-3A and 8 months for FY-3B in orbit. The observation from ERM on FY-3C has been in good condition for 9 years  In this presentation the performance of ERMs calibration in orbit is evaluated with CERES from EOS/Aqua and GERB-3 from Meteosat. The ERM LW and SW unfiltered radiance produced with spectral correction based on atmospheric transfer modelling has a good consistence with the other data. The new ERM instrument(ERM-II), which has a broadband LW channel covering 5-50 μm besides the Total and SW channels with a NFOV scanning mode, will be launch in the coming 2023 and provide 8 years global ERB observation from next FY-3 morning satellite.

How to cite: Qiu, H. and Qi, J.: Earth Radiation Budget Measurements on Chinese FY-3 Series Polar Orbit Satellites, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4590, https://doi.org/10.5194/egusphere-egu23-4590, 2023.

EGU23-4921 | ECS | Orals | ST1.5

Estimating the Anisotropic Factor of Angular Distribution Models from Radiative Fluxes 

Huizeng Liu, Ping Zhu, Shaopeng Huang, and Qingquan Li

Global climate change has aroused widespread concerns in society regarding the sustainable development of human beings. The Earth’s radiation budget (ERB) at the Top-of-Atmosphere (TOA) includes incident solar radiation, Earth-reflected shortwave radiation, and outgoing longwave radiation. The accuracy of the existing spaceborne instruments still cannot meet the measurement requirement of the Earth’s TOA shortwave and longwave radiation. In recent years, several novel observing platforms and sensors have been proposed for ERB. Hitherto, most of those concepts for ERB are still in the phase of design and development, and studies have been mainly carried out based on simulations. Simulating the sensor-measured signals of the proposed novel platforms, sensors or constellations could help to optimize the sensor parameters, determine the number of satellites in the constellation, explore their potentials in characterizing the ERB. The anisotropic factor, depicting the anisotropy of Earth’s radiation, is essential in the simulation. However, developing angular distribution models involves complex procedures of data preparation, processing, and modeling. This study, targeting at simplifying the procedure of simulating the signals of ERB sensors, proposed an approach of estimating the longwave anisotropic factors directly from the Earth’s radiative fluxes. The approach was implemented with CERES data and the neural network algorithm. Models were developed for 10 scene types based on Earth’s surface types. Results showed that the longwave anisotropic factors were accurately estimated with the correlation coefficient (r) varying between 0.85 and 0.98 and MAPE within 1.20% for the test dataset. With the estimated anisotropic factors, the sensor-measured radiances were accurately retrieved with r=1.00 and MAPE=0.53%. Therefore, the proposed approach is promising in accurate and efficient simulations of novel ERB platforms and sensors like the Moon-based Earth Radiation.

How to cite: Liu, H., Zhu, P., Huang, S., and Li, Q.: Estimating the Anisotropic Factor of Angular Distribution Models from Radiative Fluxes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4921, https://doi.org/10.5194/egusphere-egu23-4921, 2023.

EGU23-5900 | Posters on site | ST1.5

Solar total radiation input and terrestrial temperature in the two millennia of 600-2600 

Valentina Zharkova, Irina Vasilieva, and Elena Popova

The  long-term millennial oscillations of the baseline  solar background magnetic field (SBMF) and the ephemeris of  the Sun-Earth distances are compared with the oscillations of solar irradiance at the terrestrial biomass (Hallstatt's cycle).    

Based  the Sun-Earth distances derived from the current JPL ephemeris based on solar inertial motion and gravitational effects on the Sun by four large planets: Jupiter, Saturn, Neptune and Uranus we  demonstrate the S-E distance is reduced by 0.005 au in the millennium M1 600-1600 and 0.011 au in millennium M2 1600-2600. We show that variations of the Sun-Earth distances  are accountable for the increase of the solar irradiance by about $20-25$ $Wm^{-2}$ since 1700 that will continue to last until 2500. he decrease of the S-E distance per century in the current millennium follows the  rate of the terrestrial temperature increase reported since MM. We evaluate that this difference of the Sun-Earth distances caused by SIM  leads to the different magnitudes of solar irradiance deposited in the Northern and Southern hemispheres  in M2 with thee Northern hemisphere to obtain more radiation compared to the Southern one. These estimations show that in the next 600 years the Sun will continue moving towards the Earth  that will result in a further increase of solar irradiance and the baseline terrestrial temperature  in 2500-2600. These variations are expected to be over-imposed by a reduction of solar activity during two grand solar minima (GSMs) with a reduce terrestrial temperatures by 1C  to occur  in 2020-2053 and 2370-2415. 

How to cite: Zharkova, V., Vasilieva, I., and Popova, E.: Solar total radiation input and terrestrial temperature in the two millennia of 600-2600, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5900, https://doi.org/10.5194/egusphere-egu23-5900, 2023.

EGU23-7190 | ECS | Orals | ST1.5

A new approach to determine the Top of Atmosphere earth Outgoing Radiation using the Geant4 toolkit 

Manal Yasmine Boudjella, Ahmed Hafid Belbachir, Samy Anis Amine Dib, and Mustapha Meftah

Monitoring accurately the amount of the incoming solar radiation reaching the ground surface and the outgoing radiation at the top of the atmosphere (TOA) is crucial for quantifying the earth's energy budget as well as for understanding and modelling the climate system and its evolution. In the present investigation, we explore the use of the Geant4 Monte Carlo toolkit and a new reference spectrum SOLAR/SOLSPEC [1] to develop a new model to estimate the spectral distribution of Top of Atmosphere Outgoing Radiation (TOR). The system is implemented in Geant4, a toolkit [2] that simulates the passage of particles through matter. SOLAR-ISS is a high resolution solar spectrum with a mean absolute uncertainty of 1.26% at 1σ. The TOR is estimated for a clear atmosphere and at different air mass (AM). For quality analysis, the performance of this model is examined and evaluated by comparing Geant4 simulation results with those of the DISORT code, where the relative mean difference is less than 7.29% overall the spectral domain from 280 to 3000 nm for a well defined case. The characteristics, such as transmittance and reflectance, etc., of the present and previous results will be analysed and compared to evaluate the performance of Geant4. We can upgrade the current tools with more powerful, efficient, and accurate prototyping. Furthermore, We will consider the design of a graphical user interface for the creation of the simulation input file, this utility will serve as a guideline that helps the user to run a simulation.

How to cite: Boudjella, M. Y., Belbachir, A. H., Dib, S. A. A., and Meftah, M.: A new approach to determine the Top of Atmosphere earth Outgoing Radiation using the Geant4 toolkit, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7190, https://doi.org/10.5194/egusphere-egu23-7190, 2023.

EGU23-7221 | Posters on site | ST1.5

Total Solar Irradiance and Terrestrial Outgoing Longwave Radiation Measurements obtained with CLARA onboard NorSat-1 

Margit Haberreiter, Wolfgang Finsterle, Jean-Philippe Montillet, Manfred Gyo, Dany Pfiffner, Martin Mostad, Ivar Spydevold, Alex Beattie, Bo Andersen, and Werner Schmutz

The Earth Radiation Budget at the Top of the Atmosphere (ToA) governs the status of climate change on our planet. The ERB is the balance between the incoming Total Solar Irradiance (TSI) and total outgoing radiation at the ToA. If more energy is stored in the system the Earth Energy Imbalance is positive and the temperature in the system rises. The Compact Lightweight Absolute RAdiometer (CLARA) experiment onboard the Norwegian micro satellite NorSat-1 is an SI traceable radiometer with the primary science goal to measure TSI from space. Besides TSI, CLARA also measures the terrestrial Outgoing Longwave Radiation (OLR) at the ToA on the night side of Earth. We present the latest status of the data and degradation correction obtained with this SI-traceable radiometer and compare the CLARA TSI and OLR time series with other available observations and reanalysis data. The validation of these measurements is key to advance our capability to determine the Earth Energy Imbalance from space. 

How to cite: Haberreiter, M., Finsterle, W., Montillet, J.-P., Gyo, M., Pfiffner, D., Mostad, M., Spydevold, I., Beattie, A., Andersen, B., and Schmutz, W.: Total Solar Irradiance and Terrestrial Outgoing Longwave Radiation Measurements obtained with CLARA onboard NorSat-1, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7221, https://doi.org/10.5194/egusphere-egu23-7221, 2023.

EGU23-9007 | Posters on site | ST1.5

The DARA/PROBA-3 radiometer: results from the preflight calibration campaign 

Jean-philippe Montillet, Werner Schmutz, Wolfgang Finsterle, Greg Kopp, Silvio Koller, Daniel Pfiffner, Manfred Gyo, Ricco Soder, Matthias Gander, Lloyd Beeler, Patrick Langer, Marcel Spescha, Pascal Schlatter, Jakob Föller, Margit Haberreiter, Karl Heuerman, and Andrei Zukhov

The Project for On-Board Autonomy-3 (PROBA-3) is the fourth satellite technology development and demonstration precursor mission within ESA's GSTP (General Support Technology Program) series. The primary mission objective is to demonstrate the technologies required for formation flying of multiple spacecrafts. The PROBA-3 mission concept comprises two independent minisatellites in highly-elliptical Earth orbits in precise formation flying, close to one another with the ability to accurately control the attitude and separation of the two satellites. The mission launch is scheduled for end of 2023.

PROBA-3 mission consists of a coronograph spacecraft, hosting the coronograph APIICS, and the occulter spacecraft with the Digital Absolute RAdiometer (DARA).  The radiometer to record total solar irradiance is mounted on the front satellite pointing to the Sun. DARA is  developed and manufactured in Switzerland by the PMOD/WRC. We have done two pre-flight calibration campaigns: one at the World Radiation Center in Davos, Switzerland, and one at the Total Solar Irradiance (TSI) Radiometer Facility of the Laboratory for Atmospheric and Space Physics in Boulder Colorado, USA. We report on the results of the laboratory comparisons and discuss uncertainties of several instrument parameters, which are used to transform the raw measurements, which are voltage and current, into solar irradiance values. 

How to cite: Montillet, J., Schmutz, W., Finsterle, W., Kopp, G., Koller, S., Pfiffner, D., Gyo, M., Soder, R., Gander, M., Beeler, L., Langer, P., Spescha, M., Schlatter, P., Föller, J., Haberreiter, M., Heuerman, K., and Zukhov, A.: The DARA/PROBA-3 radiometer: results from the preflight calibration campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9007, https://doi.org/10.5194/egusphere-egu23-9007, 2023.

EGU23-9484 | Posters on site | ST1.5

High-resolution solar spectrum obtained from TGO orbiting Mars reveals new solar lines in the 0.7-1.7 µm range 

Abdanour Irbah, Jean-Loup Bertaux, Franck Montmessin, Alexander Trokhimovskiy, Oleg Korablev, and Anna Fedorova

The ACS-NIR spectrometer on board the Trace Gas Orbiter (TGO) is currently used to probe the atmosphere of Mars. It is, however, capable of measuring the near-infrared solar spectrum in the 0.7-1.7 µm domain with high spectral resolution when pointed at the Sun and its line of sight is above the atmosphere of Mars i.e. with its Solar Occultation mode. Specific observations were therefore made during 10 months in order to construct the solar spectrum in this spectral domain. The observations consist in recording all the diffraction orders of ACS-NIR by continuously varying the frequency of its AOTF (Acousto-Optic Tunable Filters, a component used to separate the orders). We will first present how we have treated each order of diffraction to improve the solar spectrum on the 0.7-1.7 µm band by considering for this purpose off-center images attached to certain AOTF frequencies. This method makes it possible to avoid contamination between the successive diffraction orders but also to increase the detection of the solar lines at the ends of each order where the intensity is low due to the Blaze function. We will then show the final version of the solar spectrum that we obtain. It will be compared to the reference spectrum, which is that of Toon. We will finish by showing and discuss some results revealing new solar lines appearing in certain diffraction orders of the ACS-NIR spectrometer and which are not present in the corresponding parts of the reference solar spectrum. 

How to cite: Irbah, A., Bertaux, J.-L., Montmessin, F., Trokhimovskiy, A., Korablev, O., and Fedorova, A.: High-resolution solar spectrum obtained from TGO orbiting Mars reveals new solar lines in the 0.7-1.7 µm range, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9484, https://doi.org/10.5194/egusphere-egu23-9484, 2023.

EGU23-10082 | Orals | ST1.5

GOES EUVS Magnesium II Index: The beginning of a new climate data record 

Martin Snow, William McClintock, Janet Machol, Frank Eparvier, and Don Woodraska

The GOES-R series spacecraft include a new operational measurement for GOES satellites, the Magnesium II (MgII) core-to-wing index.  This solar activity proxy has been measured at a daily cadence beginning in 1978.  It is widely used in solar spectral irradiance models such as the NRLSSI CDR (Coddington et al. 2016).  The C Chanel of the Extreme and Ultraviolet Spectrograph (EUVSC) on GOES 16 began making operational MgII index measurements at high cadence in early 2017.  There are currently three such instruments in orbit on GOES 16, 17, and 18 as part of the EXIS suite of solar irradiance instruments.  In the past, the MgII index was only measured a few times per day, but EXIS makes measurements at a 3-second cadence to monitor rapid changes in the Sun.

In this presentation, we will describe the available data product and how it compares with previous measurements.  On long timescales it can be used to extend the historical record, and on short timescales it reveals solar activity of interest to space weather practitioners.

How to cite: Snow, M., McClintock, W., Machol, J., Eparvier, F., and Woodraska, D.: GOES EUVS Magnesium II Index: The beginning of a new climate data record, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10082, https://doi.org/10.5194/egusphere-egu23-10082, 2023.

EGU23-10126 | Posters on site | ST1.5

GHOTI: GOES-R High-cadence Operational Total Irradiance 

Steven Penton, Martin Snow, Stephane Beland, Woodraska Don, and Coddington Odele

The EXIS (Extreme ultraviolet and X-ray Irradiance Sensors) detectors on the GOES-R spacecraft (GOES-16, GOES-17 & GOES-18) use quad-diode Sun Positioning Sensors (SPS) to maintain precision pointing. The 4 Hz quad-diode signal is high-precision and we attempt to use this signal as a high-cadence proxy for Total Solar Irradiance (TSI) and use the MgII index + NRLSS2 models to predict high-cadence spectra. The quad-diode signal must be calibrated for spacecraft velocity (a 1AU correction), instrument temperature, and diode degradation with usage. In the 2nd year of this 3-year project, we report the progress of these calibrations and our efforts toward defining our TSI proxy and high-cadence spectral data products.

How to cite: Penton, S., Snow, M., Beland, S., Don, W., and Odele, C.: GHOTI: GOES-R High-cadence Operational Total Irradiance, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10126, https://doi.org/10.5194/egusphere-egu23-10126, 2023.

EGU23-10290 | ECS | Posters on site | ST1.5

The TSIS-2 TIM Instrument Pre-Flight Calibration and Uncertainty 

Ed Thiemann, Karl Heuerman, Andres Villani-Davila, and Erik Richard

The total solar irradiance (TSI) is Earth’s primary source of energy, and accurate knowledge of its value and variability is crucial for understanding Earth’s climate and variability. In order to continue the existing 44 year data record of TSI measurements from space, NASA is developing the Total and Spectral Irradiance Sensors (TSIS) -2 mission. TSIS-2 consists of the Total Irradiance Monitor (TIM) and Spectral Irradiance Monitor (SIM) on a free flyer satellite, with an anticipated launch in the latter half of 2024. The TSIS-2/TIM is the latest iteration of the TIM instrument, prior versions of which flew onboard the SORCE, TCTE and TSIS-1 missions, and a direct rebuild of the TSIS-1 instrument. We present the pre-flight ground calibration of the TSIS-2/TIM instrument and its uncertainties. A key difference between the calibrations of the TSIS-1 and TSIS-2 instruments is the use of a novel low noise ambient temperature radiometer for TSIS-2 that significantly reduces the uncertainty in validating the component level calibrations through an end-to-end measurement. We compare component level (e.g. aperture area, detector reflectance, etc.) measurements and uncertainties for TSIS-2 with those from TSIS-1, and focus on areas where the uncertainty analysis differs from that applied to TIM instruments on prior missions and the implications of these differences.

How to cite: Thiemann, E., Heuerman, K., Villani-Davila, A., and Richard, E.: The TSIS-2 TIM Instrument Pre-Flight Calibration and Uncertainty, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10290, https://doi.org/10.5194/egusphere-egu23-10290, 2023.

EGU23-10751 | Orals | ST1.5 | Highlight

On the future of Earth radiation and energy imbalance measurements 

Maria Z. Hakuba, Peter Pilewskie, and Graeme Stephens and the Libera Science Team

Libera, NASA’s first Earth Venture Continuity Mission, is in preparation to provide seamless continuity to current Earth outgoing radiance measurements conducted and processed by the Clouds and Earth’s Radiant Energy System (CERES) project. Leveraging advanced detector technologies, Libera will measure the broadband total, longwave, and shortwave radiances akin to CERES and achieve radiometric uncertainty of approximately 0.2%. Beyond the crucial radiation budget continuity goal, Libera will carry a fourth radiometer in the shortwave near-infrared to advance our understanding of shortwave energy deposition in the climate system, such as related to the characterization of processes relevant for shortwave absorption, climate feedbacks, and Earth’s albedo variability with added insight into hemispheric albedo symmetry given the hemispheric differences in ocean, continent and cloud distributions. We use global model simulations and radiative transfer calculations as proxies for Libera’s future data record to demonstrate applications of the shortwave sub-band knowledge in climate science. Although Libera’s absolute accuracy is unprecedented, it is still insufficient to adequately close Earth’s energy budget. We will therefore discuss current and future avenues to indirectly and directly measure EEI from space. The latter is potentially feasible through sensing radiation pressure-induced accelerations acting on near-spherical spacecrafts, which under optimal conditions, are directly proportional to the net radiative flux experienced at the satellite’s location. This approach has been considered in the past, and the feasibility to achieve a measurement accuracy within 0.3 Wm-2 is currently under investigation. 

  

How to cite: Hakuba, M. Z., Pilewskie, P., and Stephens, G. and the Libera Science Team: On the future of Earth radiation and energy imbalance measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10751, https://doi.org/10.5194/egusphere-egu23-10751, 2023.

EGU23-12178 | ECS | Orals | ST1.5

The Earth Climate Observatory (ECO) space mission concept for themonitoring of the Earth Energy Imbalance (EEI) 

Lien Smeesters, Steven Dewitte, and Thorsten Mauritsen

Monitoring the Earth Radiation Budget (ERB) and in particular the Earth
Energy Imbalance (EEI), is of paramount importance for a predictive
understanding of global climate change.   We propose the new Earth
Climate Observatory (ECO) space mission concept for the monitoring of
the EEI.

The EEI is defined as the small difference between the two nearly equal
terms of the incoming solar radiation, and the outgoing terrestrial
radiation lost to space. Making a significant measurement of the EEI
from space is very challenging, and requires a differential measurement
with one single instrument of both the incoming solar radiation and the
outgoing terrestrial radiation. The instrument that allows such a
differential measurement is an improved wide field of view electrical
substitution cavity radiometer.

The wide field of view radiometer will observe the earth from limb to
limb. A single measurement footprint is a circle with a diameter around
6300 km. For the discrimination of cloudy and clear skies, a higher
spatial resolution is needed. This will be obtained from two wide field
of view cameras, a visible wide field of view camera for the
characterisation of the spatial distribution of the reflected solar
radiation, and a thermal infrared wide field of view camera for the
characterisation of the spatial distribution of the emitted thermal
radiation.

How to cite: Smeesters, L., Dewitte, S., and Mauritsen, T.: The Earth Climate Observatory (ECO) space mission concept for themonitoring of the Earth Energy Imbalance (EEI), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12178, https://doi.org/10.5194/egusphere-egu23-12178, 2023.

EGU23-12185 | ECS | Orals | ST1.5

INSPIRE-SAT7: Pre-Flight radiometric validation and calibration of a miniaturized Earth’s Radiative Budget satellite 

Lionel Van Laeken, David Bolsée, Nuno Pereira, Mustapha Meftah, Alain Sarkissian, Luc Damé, Christophe Dufour, and the INSPIRE-SAT team

INSPIRE-SAT 7 is a French 2-Unit CubeSat primarily designed for Earth and Sun observations.  This mission is part of the International Satellite Program in Research and Education (INSPIRE). This satellite will be deployed in Low Earth Orbit (LEO) in 2023 as the first step of the so-called ‘Terra-F’ constellation that will provide spatio-temporal resolution for Earth Energy Imbalance (EEI) measurements.

This new scientific and technological pathfinder CubeSat mission (INSPIRE-SAT 7) is equipped with various channels on all sides. Among them: the Total Solar Irradiance Sensor (TSIS) payload, the Ultra-Violet Sensor (UVS) using a new generation of solar blind detectors designed to monitor the integrated Solar Spectral Irradiance (SSI) in the Hertzberg continuum, and the Earth Radiative Sensor (ERS) payload, designed to measure some Earth’s Radiative budget (ERB) components such as the outgoing short and long wave radiation at the top-of-the atmosphere for climate change studies.

The Belgian Radiometry Characterization Laboratory (B.RCLab) of the Royal Belgian Institute for Space Aeronomy (BIRA-IASB) is the partner responsible for the pre-flight absolute calibration and radiometric characterization of INSPIRE-SAT7 TSIS and UVS payloads.

In this work we will first describe the INSPIRE-SAT7 concept, design, scientific and operational objectives. We will then present B.RCLab facilities along with its radiometric characterization benches, including the absolute calibration capabilities and its traceability. Finally, the main results of the INSPIRE-SAT7 pre-flight calibration campaign, which took place in November 2022, will be presented. These results allowed to calculate the sensors on-orbit calibration coefficients that are crucial to perform traceable absolute EEI measurements. A radiometric comprehensive uncertainty budget will be presented along the sensors’ calibration coefficients.

How to cite: Van Laeken, L., Bolsée, D., Pereira, N., Meftah, M., Sarkissian, A., Damé, L., Dufour, C., and team, T. I.-S.: INSPIRE-SAT7: Pre-Flight radiometric validation and calibration of a miniaturized Earth’s Radiative Budget satellite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12185, https://doi.org/10.5194/egusphere-egu23-12185, 2023.

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 through direct measurements of spectrally resolved solar reflected Earth radiances and Sun irradiances becoming a ‘gold standard’ reference in support of climate emergency research and operational applications. It aims to establish a “metrology laboratory in space” by creating a fiducial, SI-traceable reference data set to cross-calibrate other sensors and improve the quality of their data.

TRUTHS main objective is to establish a reference baseline measurement (benchmark) of the state of the planet, against which past and future observations can be compared, in order to:

  • allow climate model improvements and forecast testing, and
  • provide observational evidence of climate change, including mitigation strategies in the shortest time possible.

TRUTHS will primarily measure the incoming and outgoing energy from the climate system with an accuracy needed to detect climate trends in the shortest possible time.

The datasets needed to meet this objective have many additional applications, such as:

  • SI traceable measurements of the incoming and reflected solar spectrum, to address direct science questions.
  • Operational products for removing radiometric biases in other satellite instruments by cross-calibration with TRUTHS data, improving accuracy and enabling inter-operability including improvement of 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; to the Moon.

The mission comprises an “agile” satellite capable to point and image the Earth, the Moon and the Sun in a polar orbit hosting the Hyperspectral Imaging Spectrometer (HIS) capable to provide an accurate, continuously calibrated, dataset of spectrally resolved solar and lunar irradiance and Top of Atmosphere (ToA) Earth-reflected radiance in the near-UV/Visible/NIR/SWIR (320 nm to 2400 nm) waveband 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, the Cryogenic Solar Absolute Radiometer (CSAR), as part of an innovative On-Board Calibration System (OBCS), allowing the HIS observations to achieve its unprecedented in-space accuracy, targeting an expanded radiometric uncertainty tied to international SI standards of 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, in relation to interoperability and accuracy. The mission is being developed by an industrial consortium led by Airbus Defence and Space UK.

The TRUTHS mission targets a launch in 2030 with a minimal life-time of 5 years, and design goal to reach 8 years, of in-orbit operations. It will become part of a future fleet of SI-Traceable Satellites (SITSATs) currently being developed by different space agencies, including CLARREO-Pathfinder (NASA) and CSRB (CMA), and together with FORUM (ESA) and IASI-NG (EUMETSAT) will provide spectrally resolved Earth radiance information from the UV to the Far-Infrared in the coming decade.

How to cite: Fehr, T., Fox, N., Marini, A., and Remedios, J.: Traceable Radiometry Underpinning Terrestrial- and Helio- Studies (TRUTHS) – A ‘gold standard’ imaging spectrometer in space to support climate emergency reseaerch, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12399, https://doi.org/10.5194/egusphere-egu23-12399, 2023.

EGU23-12518 | Orals | ST1.5 | Highlight

Fengyun Program and Solar Observation Activities 

Peng Zhang, Jin Qi, Xin Ye, Yu Huang, and Ping Zhu

Fengyun 3 series (FY-3) is the second generation polar orbiting meteorological satellite in China. There are 5 satellites have been launched since the first satellite FY-3A in 2008. The solar irradiance is one of important parameters to measure by FY-3 series. The instrument to measure the solar irradiance is called Solar Irradiance Monitor (SIM). The SIM was deployed on the orbit since FY-3A (morning orbit AM) in 2008 and FY-3B (afternoon orbit PM) in 2010. SIM was upgraded to SIM-II mounted on FY-3C (AM orbit) in 2013. The sensitivity, absolute accuracy and stability of the instrument has been improved with the more accurate control on the solar disk tracking system and instrument environment temperature maintaining system. The SIM-II together with the Solar Spectral Irradiation Monitor (SSIM) have been deployed on the orbit mounted on FY-3E (early-morning orbit EM) in 2021. This presentation overviews the FY program. The specification and performance of SIM, SIM-II and SSIM have been illustrated. The measured Total Solar Irradiance (TSI) product has been compared with the similar measurements on SOHO/VIRGO, SORCE, TSIS-1, etc. The future plan for the solar measurements in FY-3 series has been presented in the last part.

How to cite: Zhang, P., Qi, J., Ye, X., Huang, Y., and Zhu, P.: Fengyun Program and Solar Observation Activities, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12518, https://doi.org/10.5194/egusphere-egu23-12518, 2023.

EGU23-13188 | Posters on site | ST1.5

The TSI and SSI measurement from Fengyun-3E Satellite 

Jin Qi, Peng Zhang, Hong Qiu, Ling Sun, Xin Ye, Wei Fang, and Yu Huang

Fengyun-3E is an early-morning orbit meteorological satellite which provided more opportunity to observe solar activities and was launched on July 5, 2021. The total solar irradiance is measured by Solar Irradiance Monitor-II (SIM-II) which has been improved on degradation monitor compared to earlier Fengyun satellite. The spectral solar irradiance is observed by the new payload Solar Spectral Irradiance Monitor (SSIM) which could provide continuous spectra from 165nm~2400nm. The SSIM instrument has three wavebands: UV band from 165 nm to 320 nm, VIS band from 285 nm to 700 nm, NIR band from 650 nm to 2400 nm, with spectral resolution as 1nm, 1nm and 8nm, respectively. In this work, we will present the design of solar observation, instruments on-orbit performance and preliminary results of FY-3E solar measurement.

How to cite: Qi, J., Zhang, P., Qiu, H., Sun, L., Ye, X., Fang, W., and Huang, Y.: The TSI and SSI measurement from Fengyun-3E Satellite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13188, https://doi.org/10.5194/egusphere-egu23-13188, 2023.

EGU23-15415 | ECS | Orals | ST1.5

Validation of DSCOVR-based albedo estimate using a weather model 

Maksym Vasiuta, Lauri Tuppi, Antti Penttilä, Karri Muinonen, and Heikki Järvinen

The Deep Space Climate Observatory (DSCOVR) is located near the Lagrangian L1 point of the Earth. Their EPIC images indicate exceptionally large values of the Earth's planetary albedo in December 2020, having daily average surged above 0.320 for consecutive three weeks. Independent evaluation of the Earth’s albedo using a numerical weather prediction model (OpenIFS of ECMWF) suggests that this is an over-estimate. Given the difference between satellite-based and model-based albedo estimates, the reconstructed from images top-of-atmosphere short-wave radiosity is over-estimated. We suggest the discrepancy is explained by a weakness of short-wave angular distribution models (ADMs) based on Clouds and the Earth's Radiant Energy System’s The Tropical Rainfall Measuring Mission (CERES/TRMM) in full back-scattering geometry. This conclusion is supported by disk-integrated short-wave anisotropy factors in December 2020, estimated using CERES ADMs, being lower than measured by NIST Advanced Radiometer (NISTAR).

How to cite: Vasiuta, M., Tuppi, L., Penttilä, A., Muinonen, K., and Järvinen, H.: Validation of DSCOVR-based albedo estimate using a weather model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15415, https://doi.org/10.5194/egusphere-egu23-15415, 2023.

EGU23-15701 | ECS | Posters on site | ST1.5

Solar irradiance estimation for planetary studies 

Isabela de Oliveira, Krishnamurthy Sowmya, Nina-Elizabeth Nèmec, and Laurent Gizon

Solar irradiance is the main source of energy input to the planets of the Solar System. The solar rotation and the evolution of active regions on the surface of the Sun are two of the sources of solar irradiance variability. Nèmec et al. (2020) showed that the variability of solar irradiance is dominated by one of these two sources depending on the timescale of interest. The solar rotation dominates the variability for periods between 4-5 days and the synodic solar rotation period (27.3 days), while the evolution of active regions dominate for the remaining timescales.

Usually, the irradiance measurements at Earth are extrapolated to estimate the irradiance at other planets and study the effect of solar irradiance on other planets' atmospheres (Thiemann et al., 2017). In this "lighthouse model", the irradiance source regions on the surface of the Sun are assumed to simply rotate with a Carrington sidereal period of 25.38 days. This means that the solar rotation is the only cause of variability of the irradiance in this model, and the evolution of active regions is neglected.

In this work, we develop a model to calculate the irradiance at other planets by accounting for the evolution of magnetic features. Our method follows the Spectral And Total Irradiance REconstruction (SATIRE; Fligge et al. 2000; Krivova et al. 2003) approach and works by Nèmec et al. (2020) and Sowmya et al. (2021). First, the Surface Flux Transport Model (SFTM; Cameron et al. 2010) is used to obtain the time-dependent surface distribution of magnetic features (faculae and spots). Then, the solar irradiance is calculated as the sum of the contributions from the quiet Sun (i.e., regions with no magnetic activity), faculae, and spots. 

Our method allows calculating the solar irradiance directly at a given position within the ecliptic, regardless of the position of the Earth. We compare our irradiance calculations with those of the extrapolation method. We find that taking the evolution of active regions into account improves the estimation of solar irradiance significantly, especially when it comes to wavelengths in the visible and infrared ranges. Therefore, we suggest that our method provides more accurate estimates of solar irradiance to be used as input in studies of planetary atmospheres.

We would like to note that our method of irradiance calculation is currently only statistical. We use the SFTM as we do not have information of the areas of the far-side of the Sun, which are needed in order to get the correct rotational variability. To determine real daily values of irradiance, we need to combine our calculations with methods of helioseismology, which is still a work in progress.

How to cite: de Oliveira, I., Sowmya, K., Nèmec, N.-E., and Gizon, L.: Solar irradiance estimation for planetary studies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15701, https://doi.org/10.5194/egusphere-egu23-15701, 2023.

EGU23-16293 | Orals | ST1.5

Reconstructing solar irradiance over the period 1996-2022 

Ilaria Ermolli and Theodosios Chatzistergos

Knowledge of solar irradiance variability is critical to Earth's climate models and understanding the solar influence on Earth's climate. Direct measurements of the Total Solar Irradiance (TSI) have only been available since 1978 from instruments onboard multiple missions. Different calibrations of the individual instruments make estimates of the possible long-term trend in the TSI still uncertain. Knowledge of the Solar Spectral Irradiance (SSI) is even more undetermined. Here we use the carefully reduced observations from the Rome Precision Solar Photometric Telescope (Rome/PSPT) and semi-empirical irradiance models to reconstruct solar irradiance variations over the period 1996-2022. Results are discussed with respect to direct measurements and existing composite reconstructions.

How to cite: Ermolli, I. and Chatzistergos, T.: Reconstructing solar irradiance over the period 1996-2022, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16293, https://doi.org/10.5194/egusphere-egu23-16293, 2023.

EGU23-16858 | Posters on site | ST1.5

Exploring New Instrument deGradation Models and Algorithms (ENIGMA) 

Stéphane Béland and Steven Penton

The Solar Radiation and Climate Experiment measured Total Solar Irradiance (TSI) 
and Solar Spectral Irradiance (SSI) from 2003 to 2020. The Solar Irradiance Monitor (SIM) 
instrument measured SSI from 200nm to 2400 nm on a daily basis. The current SORCE-SIM
instrument degradation correction uses a measurement equation derived from
accessible telemetry, the known instrument refraction geometry, inter-detector comparisons,
and inter-spectrometer comparisons. While the current degradation model captures much of the
long-term trending, some of the parameters were adjusted without well-defined physical
interpretations.

The degradation model used for SORCE-SIM is not unique. We're reporting on work to Explore New
Instrument degradation Models and Algorithms (ENIGMA) to address issues with the current
model and with the derived corrected irradiances. The development of enhanced SORCE-SIM
measurement equations permits the evaluation, and potential inclusion, of degradation
mechanisms not captured in the present model.

We present an initial updated degradation model which improves our ability to construct a 
composite irradiance time series in combination with TSIS-SIM, whose measurements overlap 
with SORCE for 2 years and has well-defined uncertainties. Combining the two datasets, allowed
the construction of a consistent composite irradiance time series from 2003-2023. 

How to cite: Béland, S. and Penton, S.: Exploring New Instrument deGradation Models and Algorithms (ENIGMA), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16858, https://doi.org/10.5194/egusphere-egu23-16858, 2023.

EGU23-17162 | Posters on site | ST1.5

The first light from the joint total solar irradiance measurement experiment onboard the FY3-E meteorological satellite 

Xin Ye, Ping Zhu, Jean-Philippe Montillet, Xiuqing Hu, Jinhua Wang, Dongjun Yang, Jin Qi, Wolfgang Finsterle, Peng Zhang, Wei Fang, Silvio Koller, Daniel Pfiffner, Baoqi Song, Zhitao Luo, Kai Wang, Margit Haberreiter, Duo Wu, and Werner Schmutz

The Fengyun 3E (FY3E) spacecraft was launched on the 4th of July 2021 at 23h 28min UTC according to CASC (China Aerospace Science and Technology Corp.) on a Long March 4C vehicle from JSLC (Jiuquan Space Launch Center) in China. The orbit is a sun-synchronous near-circular with an altitude of 800 km, and an inclination of 98.7 degrees. The nominal lifetime of the satellite is eight years. The JTSIM experiments belong to the solar activities monitoring package. The solar radiation is absorbed by the black-coated cavity and the induced different heat-flux between the primary and reference cavity is measured, and the electrically calibrated differential heat-flux is used to compute the solar irradiance. SIAR has three identical channels A, B, and C, and each channel has a different solar exposure time to study the instrument’s nonlinear drift due to degradation. DARA also has three cavity radiometers and electrical substitution radiometers (Channel A, Channel B, and Channel C). The difference is that they are aligned in a triangle. Compared to VIRGO/PMO6, DARA inverts the aperture geometry to eliminate stray light. DARA and SIAR absolute radiometers are not operating at the same time due to the different designs and measurement sequences. On August 18, 2021, both instruments successfully passed the first commission phase, and they started to observe the total solar irradiance since then.

How to cite: Ye, X., Zhu, P., Montillet, J.-P., Hu, X., Wang, J., Yang, D., Qi, J., Finsterle, W., Zhang, P., Fang, W., Koller, S., Pfiffner, D., Song, B., Luo, Z., Wang, K., Haberreiter, M., Wu, D., and Schmutz, W.: The first light from the joint total solar irradiance measurement experiment onboard the FY3-E meteorological satellite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17162, https://doi.org/10.5194/egusphere-egu23-17162, 2023.

EGU23-485 | ECS | Posters on site | ST1.6

Deciphering Faint Gyrosynchrotron Emission from Coronal Mass Ejection using Spectro-polarimetric Radio Imaging 

Devojyoti Kansabanik, Surajit Mondal, and Divya Oberoi

Measurements of the plasma parameters of coronal mass ejections (CMEs), particularly the magnetic field and non-thermal electron population 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 been regarded as  one of the most promising methods to estimate spatially resolved CME plasma parameters remotely. The very low flux density of CME GS emission, however, makes this rather  challenging. This challenge has recently been overcome using the high dynamic range imaging capability of the Murchison Widefield Array (MWA). Although the detection of GS is now possible routinely, the large number of free parameters of the GS models and some degeneracies between the values of these parameters make it hard to estimate all of them from the observed spectrum alone. These degeneracies can be broken using polarimetric imaging. In this work, we demonstrate this using our newly developed capability of robust polarimetric imaging on the data from the MWA. Very interestingly, we find that spectro-polarimetric imaging not only breaks the degeneracies but also provides tighter constraints on a larger number of plasma parameters than possible with total intensity spectroscopic imaging alone. 

How to cite: Kansabanik, D., Mondal, S., and Oberoi, D.: Deciphering Faint Gyrosynchrotron Emission from Coronal Mass Ejection using Spectro-polarimetric Radio Imaging, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-485, https://doi.org/10.5194/egusphere-egu23-485, 2023.

EGU23-2405 | Posters on site | ST1.6

A Titov-Dèmoulin Type CME Generator for Finite β Plasmas 

Igor Sokolov, Tamas Gombosi, and Lulu Zhao

We provide exact analytical solutions for the magnetic field produced by prescribed current distributions located inside a toroidal filament of finite thickness. In application to the MHD equilibrium of a twisted toroidal current loop in the solar corona, the Grad-Shafranov equation is decomposed into an analytic solution describing an equilibrium configuration against the pinch-effect from its own current and an approximate solution for an external strapping field to balance the hoop force.  Our solutions can be employed in numerical simulations of coronal mass ejections. When superimposed on the background solar coronal magnetic field, the excess magnetic energy of the twisted current loop configuration can be made unstable by applying flux cancellation to reduce the strapping field. Such loss of stability accompanied by the formation of an expanding flux rope is typical for the Titov-Dèmoulin eruptive event generator. The main new features of the proposed model are:

i)   The filament is filled with finite β plasma with finite mass and energy,
ii)  The model describes an equilibrium solution that will spontaneously erupt due to magnetic reconnection of the strapping magnetic field arcade, and
iii) There are analytic expressions connecting the model parameters to the asymptotic velocity and total mass of the resulting CME, providing a way to connect the simulated CME properties to multipoint coronograph observations.

How to cite: Sokolov, I., Gombosi, T., and Zhao, L.: A Titov-Dèmoulin Type CME Generator for Finite β Plasmas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2405, https://doi.org/10.5194/egusphere-egu23-2405, 2023.

EGU23-2841 | ECS | Orals | ST1.6

Variations of high time resolution heavy ion characteristics in the complex May 2005 ICME 

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

Coronal Mass Ejections~(CMEs) are extremely dynamical large scale events in which plasma-not only the coronal plasma-is ejected into the interplanetary space. Their interplanetary counterparts measured in-situ are Interplanetary Coronal Mass Ejections (ICMEs), which is also an important part of space weather.

Even though the kinetic properties of the plasma might change because of dynamic effects occurring during the expansion of the CME, the heavy ion characteristics remain unchanged after it leaves the low corona. Charge states of heavy ions reflect important information about the coronal temperature profile due to the freeze-in effect, while elemental abundances indicate potential source regions of the plasma.

With the help of the Pulse Height Analysis (PHA) data from the Solar Wind Ion Composition Spectromet (SWICS) on board the Advanced Composition Explorer (ACE), combined with a newly developed multi-population model, we are able to conduct a high time resolution (12 minutes) case study on a complex ejecta detected by ACE in May 2005. This case lasted more than 80 hours and caused a strong geomagnetic response, with a Dst index at -247.

Multiple discontinuous periods with highly charged heavy ions are identified, elemental abundances also differ during those ”hot” periods. Heavy ion characteristics provide us an unique opportunity to see the boundaries of different parts of an ICME.

How to cite: Gu, C., Heidrich-Meisner, V., and Wimmer-Schweingruber, R. F.: Variations of high time resolution heavy ion characteristics in the complex May 2005 ICME, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2841, https://doi.org/10.5194/egusphere-egu23-2841, 2023.

EGU23-3444 | ECS | Orals | ST1.6

Quantifying the effect of CME erosion on geo-effectiveness using EUHFORIA 

Anwesha Maharana, Yarrik Vanwalleghem, Tinatin Baratashvili, and Stefaan Poedts

Coronal mass ejections (CMEs) interact with large-scale solar wind structures and other CMEs during their propagation in the heliosphere and undergo erosion, deflection, and deformation. In this work, we aim to quantify the erosion of the CMEs in different solar wind backgrounds using 3D MHD simulations. The EUropean Heliosphere FORecasting Information Asset (EUHFORIA; Pomoell and Poedts, 2018) is employed to create a relaxed solar wind background and evolve a CME on top of it between 0.1 au and 2 au. The LFF spheromak model is used to model the CME. Initially, we assume a simple dipolar background wind mimicking a solar minimum condition. CMEs with different geometric and magnetic field parameters (geometrical size, chirality, polarity, and magnetic flux) are evolved, and the evolution of the CME mass and the magnetic flux contained in the magnetic cloud is tracked to quantify mass and flux erosion. We also quantify the deformation of the CME during its evolution by parameterizing the separatrix surface of the magnetic cloud. The same experiment is repeated in the presence of a stream interaction region (SIR) interacting with the CME. We characterise the deformation of the different sides of the CME (with and without the interaction with SIR). In addition, we explore the adaptive mesh refinement and stretched grid features of the upgraded EUHFORIA heliospheric wind model, i.e., the newly developed ICARUS model (Verbeke et al., 2022) to resolve the CME shock and magnetic cloud and find the conditions to improve the modelling of the sheath region. Although the analysis of CME erosion has been carried out in 2.5D (axisymmetric) in previous works (Hosteaux et al., 2021), we explore the differences in 3D, which is required to fully quantify the erosion and deformation, and investigate their effect on the CME arrival time and geo-effectiveness at Earth.

How to cite: Maharana, A., Vanwalleghem, Y., Baratashvili, T., and Poedts, S.: Quantifying the effect of CME erosion on geo-effectiveness using EUHFORIA, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3444, https://doi.org/10.5194/egusphere-egu23-3444, 2023.

EGU23-3579 | ECS | Orals | ST1.6

Validation of the magnetized ICME model with a multi-spacecradt study in Icarus 

Tinatin Baratashvili, Benjamin Grison, Brigitte Schmieder, and Stefaan Poedts

Coronal Mass Ejections (CMEs) are the main drivers of interplanetary shocks and space weather disturbances. Strong CMEs directed towards Earth can have a severe impact on our planet and their timely prediction can enable us to mitigate (part of) the damage they cause. One of the key parameters that determine the geo-effectiveness of a CME is its internal magnetic configuration.

The novel heliospheric wind and CME propagation model Icarus (Verbeke et al. 2022) which is implemented within the framework of MPI-AMRVAC (Xia et al., 2018) 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. The different refinement and coarsening conditions and thresholds are controlled by the user. These techniques result in optimized computer memory usage and a significant execution speed-up, which is crucial for forecasting purposes. 

In this study we validate a new magnetized CME model in Icarus by simulating  interplanetary coronal mass ejections (ICMEs).  We chose particular CME events observed at different radial distances from the Sun by MESSENGER and ACE. We aim to model two CME events, to examine the capabilities of the model in different configurations. We identify the originating active region for the CME of interest, reconstruct its characteristic parameters and initiate the CME propagation inside Icarus with a spheromak CME model. We focus on estimating the accuracy of the arrival time, the shock strength and the magnetic field components of the CME model in Icarus. Using observations of different satellites we can track the propagation of the CMEs in the heliospheric domain and assess the accuracy of the model at different locations.

Different AMR criteria are used to achieve higher spatial resolutions at propagating shock fronts and in the interiors of the ICMEs. This way the complex structure of the magnetic field and the deformation and (plasma and magnetic flux) erosion can be simulated with higher accuracy due to the advantage of AMR. Higher resolution is especially important for the spheromak model, because the internal magnetic field configuration affects the CME evolution and its interaction with the magnetized heliospheric wind significantly. We assess the capabilities of AMR at different locations in Icarus. Finally, the obtained synthetic time-series of plasma quantities at different satellite locations are compared to the available observational data. As a result, Icarus allows us to model CMEs with higher accuracy, yet efficiently.

TB acknowledges support from the European Union’s Horizon 2020 research and innovation program under No 870405 (EUHFORIA 2.0) and the ESA project “Heliospheric modeling techniques” (Contact No. 4000133080/20/NL/CRS).

How to cite: Baratashvili, T., Grison, B., Schmieder, B., and Poedts, S.: Validation of the magnetized ICME model with a multi-spacecradt study in Icarus, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3579, https://doi.org/10.5194/egusphere-egu23-3579, 2023.

EGU23-5303 | Posters on site | ST1.6

The electrostatic electron beam-plasma instabilities and nonlinear radio emissions. Theory vs. PIC simulations 

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

Electrostatic wave instabilities induced by energetic electron beams are believed to be at the origin of radio emissions reported by the observations of interplanetary shocks and solar coronal sources. We revisit the electron beam-plasma configurations found susceptible to nonlinear radio (electromagnetic) emissions, but which led to contradictory outcomes both in the linear theory and especially in the numerical simulations. The results of a new dispersion and stability analysis are presented, in which the electron populations are modeled both with standard Maxwellian velocity distributions and with Kappa distributions revealed by in situ measurements. We thus describe not only the exact nature of these electrostatic fluctuations (e.g., electron beam modes, modified Langmuir waves, or electron acoustic waves), but also a series of characteristics that help to distinguish them in observations. The particle-in-cell simulations confirm the predictions of the linear theory, and show for the first time how the nonlinear radio emissions are modified due to the Kappa distributions of the electron populations.

How to cite: Lazar, M., Lopez, R. A., Shaaban, S. M., and Poedts, S.: The electrostatic electron beam-plasma instabilities and nonlinear radio emissions. Theory vs. PIC simulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5303, https://doi.org/10.5194/egusphere-egu23-5303, 2023.

EGU23-5740 | Orals | ST1.6

Successive interacting coronal mass ejections: Preconditioning, magnetic reconnection and flux erosion: How to create a perfect storm? 

Ravindra Desai, Gordon Koehn, Emma Davies, Robert Forsyth, Jonathan Eastwood, and Stefaan Poedts

Coronal mass ejections (CMEs) are the largest type of eruption seen on our Sun and the primary cause of geomagnetic disturbances and storms when they arrive at the Earth. Most geomagnetic storms are created by the impact of single CME yet in a significant fraction of cases they are caused by the interaction of multiple CMEs or CMEs with other transient phenomena. In this paper we implement a spheromak CME description within our 3-D heliospheric MHD model and self-consistently model their interactions with the pre-existing solar wind and with one another. We assess their geo-effectiveness at 1 AU through quantification of the relevant solar wind variables and an empirical measures based upon solar wind-magnetosphere coupling functions. We show how the orientation and handedness of a given CME can have a significant impact on its geoeffectivness due to a prolonged conservation of toroidal flux caused by differential interplay with the Parker Spiral, and how a large range of possible CME-CME interactions can produce a diverse range of geophysical impacts at the Earth.

How to cite: Desai, R., Koehn, G., Davies, E., Forsyth, R., Eastwood, J., and Poedts, S.: Successive interacting coronal mass ejections: Preconditioning, magnetic reconnection and flux erosion: How to create a perfect storm?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5740, https://doi.org/10.5194/egusphere-egu23-5740, 2023.

EGU23-6807 | ECS | Posters on site | ST1.6

Modelling the Interaction of Alfvénic fluctuations with Coronal Mass Ejections in the low solar corona 

Chaitanya Sishtla, Jens Pomoell, Emilia Kilpua, Simon Good, and Rami Vainio

Alfvénic fluctuations of various scales are ubiquitous in the solar wind, with their non-linear interactions and eventual cascade resulting in an important heating mechanism to accelerate the solar wind via turbulent heating. Such fluctuations are also present in other transient & coherent plasma structures such as Coronal Mass Ejections (CMEs), and exhibit varying properties as compared to the solar wind plasma. In this study we investigate the interactions between solar wind Alfvénic fluctuations and CMEs using MHD simulations. We use an ideal magnetohydrodynamic (MHD) model with an adiabatic equation of state. An Alfvén pump wave is injected into the quiet solar wind by perturbing the transverse magnetic field and velocity components, and a CME is injected by inserting a flux-rope modelled as a magnetic cloud into the quasi-steady solar wind.

We observe that upstream Alfvén waves experience a decrease in frequency and change in the wave vector direction due to the non-spherical topology of the CME shock front. The CME sheath inhibits the transmission of low frequency fluctuations due to the presence of non-radial flows in this region. The frequency of the solar wind fluctuations also affect the steepening of MHD fast waves causing the CME shock propagation speed to vary with the solar wind fluctuation frequencies.

How to cite: Sishtla, C., Pomoell, J., Kilpua, E., Good, S., and Vainio, R.: Modelling the Interaction of Alfvénic fluctuations with Coronal Mass Ejections in the low solar corona, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6807, https://doi.org/10.5194/egusphere-egu23-6807, 2023.

EGU23-7061 | Orals | ST1.6

Forecasting southward pointing magnetic fields in solar coronal mass ejections 

Christian Möstl, Ute Amerstorfer, Hannah T. Rüdisser, Andreas J. Weiss, Tanja Amerstorfer, Maike Bauer, Emma E. Davies, Rachel L. Bailey, and Martin A. Reiss

The problem of forecasting southward pointing magnetic fields in coronal mass ejections (CMEs) is closely tied to our ability to measure their magnetic field configuration between the Sun and 1 AU. I will review some of the ideas that have been developed to tackle this problem, from using solar proxies, heliospheric images, Faraday rotation and measuring the in situ magnetic field near the Sun Earth-line. Another way to make progress is to use the L1 data as boundary conditions for fast ensemble simulations, focusing on the flux rope parts inside CMEs. However, for any type of modeling and forecasting we need to better understand the global magnetic structure and shape of CME flux ropes from multi-spacecraft observations, now delivered by spacecraft such as Parker Solar Probe, Solar Orbiter, BepiColombo, STEREO-Ahead and Wind, ACE or DSCOVR. In the future, the PUNCH mission will allow for the first time to extract 3D information from heliospheric images, forming another trailblazer towards developing models for ESA's Vigil mission, and setting the stage for possible interplanetary fleets of small spacecraft.



How to cite: Möstl, C., Amerstorfer, U., Rüdisser, H. T., Weiss, A. J., Amerstorfer, T., Bauer, M., Davies, E. E., Bailey, R. L., and Reiss, M. A.: Forecasting southward pointing magnetic fields in solar coronal mass ejections, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7061, https://doi.org/10.5194/egusphere-egu23-7061, 2023.

EGU23-7135 | ECS | Posters on site | ST1.6

Modeling ICME flux ropes as bent and distorted tubes 

Andreas Jeffrey Weiss, Teresa Nieves-Chinchilla, Martin Reiss, and Christian Moestl

We present the latest results in our ongoing work to construct a generalized analytical flux rope model. Our previously published writhed flux rope model is extended to include non-circular cross-sections to better mimic the magnetic field measurements that are seen in situ and imaging observations. We implement our new model within the scope of a fast forward simulation model that propagates a flux rope away from the Sun into the heliosphere and can generate synthetic magnetic field measurements at arbitrary positions. This flux rope is continuously deformed along its axis due to interaction with the ambient solar wind which is provided by other models. We use our model and the forward simulation in an attempt to reconstruct the global picture of a particular multi-point ICME event.

How to cite: Weiss, A. J., Nieves-Chinchilla, T., Reiss, M., and Moestl, C.: Modeling ICME flux ropes as bent and distorted tubes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7135, https://doi.org/10.5194/egusphere-egu23-7135, 2023.

Decades of observations have revealed that Coronal Mass Ejections (CMEs) come in a variety of forms. Some have a classic 3-part structure, whilst others can be fan shaped or jet-like. Some of these differences can be put down to projection effects, but differences in magnetic structure also play a key role. Observational and simulation studies are now highlighting that the path by which a CME flux rope traverses the solar corona, and in particular the magnetic structures it interacts with on the way, shape the ultimate characteristics of the CME further out in the heliosphere. Therefore, understanding the nature of CME flux rope interaction with the ambient corona is a key part of predicting their evolution through the heliosphere and ultimately their geoeffectiveness at Earth. In this talk I’ll discuss from a modelling perspective some recent efforts to understand this interaction process and what it tells us about CMEs on a range of scales.

How to cite: Wyper, P.: What impact does the pathway through the solar corona make on CMEs?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7312, https://doi.org/10.5194/egusphere-egu23-7312, 2023.

EGU23-7390 | Orals | ST1.6

Effects of background solar wind on the propagation of coronal mass ejection driven shock 

Chin-Chun Wu, Kan Liou, Brian wood, and Lynn Hutting

Propagation of interplanetary (IP) shocks, particularly those driven by coronal mass ejections (CMEs), is still an outstanding question in heliophysics and space weather forecasting. Here we address effects of the ambient solar wind on the propagation of two CME-driven shocks from Sun to Earth. The two CME-driven shock events (CME03: April 3, 2010 and CME12: July 12, 2012) have the following properties: (1) driven by a halo CME (i.e., source location is near Sun-Earth line), (2) a southern hemispheric CME source location, (3) similar propagation speed (e.g., took ~2 days reach the Earth), (4) occurred in the non-quiet solar period, and (4) leading to a severe geomagnetic storm. What is interesting is that the initial (near the Sun) propagation speed, as measured by coronagraph images, of CME03 was slower (~300 km/s) than CME12, but it took about same time for both events to reach the Earth. According to in-situ solar wind observations from Wind, the CME03-driven shock was associated with a faster solar wind upstream of the shock than the CME12. This is also demonstrated in our global MHD simulations. This study emphasizes the importance of the background solar wind in the propagation of CME-driven shocks. Not only the initial propagation speed near the Sun but also the ambient solar wind speed is the key to timing the arrival of CME events. The present study also demonstrated that global MHD simulations with realistic solar wind inputs is able to precisely predict the arrival of CME events.

How to cite: Wu, C.-C., Liou, K., wood, B., and Hutting, L.: Effects of background solar wind on the propagation of coronal mass ejection driven shock, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7390, https://doi.org/10.5194/egusphere-egu23-7390, 2023.

EGU23-7413 | ECS | Posters on site | ST1.6

MAFIAT: Magnetic Field Analysis Tools 

Daniel Price, Jens Pomoell, and Emilia Kilpua

Twist is an intrinsic property of magnetic flux ropes that aids in understanding their evolution and eruption. It can be difficult to compute, resulting in the common use of approximations that do not consider the geometry of the flux ropes. However, while these approximations are often relatively simple to compute, their results require careful evaluation to ensure they are correctly understood. Consequently, the magnetic field analysis tools (MAFIAT) Python package has been developed to compute the geometrically-based twist of coronal flux ropes. Here we describe MAFIAT’s initial features, its Jupyter notebook-based operation, its scientific relevance, and our plans for its future development.

How to cite: Price, D., Pomoell, J., and Kilpua, E.: MAFIAT: Magnetic Field Analysis Tools, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7413, https://doi.org/10.5194/egusphere-egu23-7413, 2023.

EGU23-7508 | ECS | Orals | ST1.6

Multi-point Investigation of CME Alfvénicity and Coherence near 1 au 

Camilla Scolini, Noé Lugaz, Réka Winslow, and Charles Farrugia

Our knowledge of the physical processes carrying information across Coronal Mass Ejections (CMEs), thereby controlling the way CME structures respond to external disturbances  in interplanetary space, is still incomplete. One prominent question is whether CMEs are “coherent” structures, i.e. potentially capable of responding in a uniform manner to external forces, and across what (macroscopic) spatial scales does such coherence exist. A necessary condition for different regions within a given CME to exhibit a coherent behavior is that they must be causally connected to the perturbation source. Past studies suggested interplanetary CMEs may behave as coherent structures only locally, and indicated that the spatial scale of coherence may be hampered by interactions with large-scale structures in the solar wind. Additionally, observational studies often assumed the correlation in the magnetic field profiles at different spacecraft locations as a proxy for coherence, but the physical link between correlation and coherence is still to be established. Characterizing the physical mechanisms mediating CME structural changes in different solar wind conditions at a fundamental level is therefore imperative to better understand their evolution and impact on space-borne and ground-based anthropic activities. 

In this study, we investigate the role of Alfvénic fluctuations (AFs) as mediators of coherence within interplanetary CMEs, and the physical relationship between correlation and coherence using multi-point observations near 1 au. In order to determine if and to what extent AFs alter CMEs at different spatial scales, we compare CME signatures at multiple spacecraft in terms of presence/absence of AFs, AF properties (if present), and correlation of magnetic signatures.  We contextualize the results in terms of the CME interaction history and the causal connection of different spacecraft observations. This study reveals how AFs affect the correlation of CME magnetic signatures across different spatial scales, and helps reconcile correlation scales within CMEs with their coherent behavior. 

How to cite: Scolini, C., Lugaz, N., Winslow, R., and Farrugia, C.: Multi-point Investigation of CME Alfvénicity and Coherence near 1 au, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7508, https://doi.org/10.5194/egusphere-egu23-7508, 2023.

EGU23-8506 | ECS | Orals | ST1.6

Investigating Flux Rope Eruptivity via Time-dependent Data-driven Modelling 

Andreas Wagner, Emilia K. J. Kilpua, Daniel J. Price, Jens Pomoell, Stefaan Poedts, Slava Bourgeois, Anshu Kumari, Farhad Daei, and Ranadeep Sarkar

Data-driven coronal models are attracting increasing attention for their ability to accurately capture the pre-eruption magnetic field configuration of active regions. However, the degree to which the current modelling techniques are able to provide information on the loss of stability and initial dynamics of the eruptions remains unclear. An interesting avenue for probing this is by employing time-dependent modelling such that the dynamic data-driving is switched-off at a given time. In this study, we investigate what we can learn from this relaxation procedure about the eruption itself and the instability that ultimately triggers it for at least two different active regions. To this effect, we use the time-dependent data-driven magnetofrictional model (TMFM) and perform multiple runs with varying relaxation times (i.e., time instances when the driving is switched off). Furthermore, we use two different physical models to simulate the coronal evolution after this point in time: the standard magnetofrictional method and a zero-beta MHD (magnetohydrodynamics) approach. In case of an eruption being triggered, the detailed evolution is characterised by tracking the associated magnetic flux rope which is extracted from the simulation data with a semi-automatic extraction algorithm. This flux rope detection and tracking procedure makes use of the twist number Tw, as well as the morphological gradient. For a further improvement of the extraction procedure, various mathematical morphology algorithms are performed to accurately extract the flux rope field lines. The properties of the extracted flux ropes are compared against their observational low-coronal manifestation in SDO/AIA data. 

How to cite: Wagner, A., Kilpua, E. K. J., Price, D. J., Pomoell, J., Poedts, S., Bourgeois, S., Kumari, A., Daei, F., and Sarkar, R.: Investigating Flux Rope Eruptivity via Time-dependent Data-driven Modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8506, https://doi.org/10.5194/egusphere-egu23-8506, 2023.

EGU23-8641 | ECS | Orals | ST1.6

Ensemble modeling of CMEs to reconstruct remote and in-situ observations 

Nishtha Sachdeva, Gabor Toth, Ward Manchester, Bart van der Holst, Aniket Jivani, and Hongfan Chen

Successful modeling of Coronal Mass Ejections (CMEs) is an important step towards accurately forecasting their space weather impact. Therefore, it is crucial to improve the various models, techniques and tools to reconstruct CMEs while validating simulations with observations of the solar corona and the inner heliosphere at various heliospheric distances with multi-viewpoint observations.

The Space Weather Modeling Framework (SWMF) includes MHD modeling of the solar wind and CMEs from the Sun to the Earth and beyond. The Alfven Wave Solar atmosphere Model (AWSoM) is a 3D extended-MHD solar corona model within SWMF that reproduces the solar wind background into which CMEs can propagate. The Eruptive Event Generator (EEG) module within SWMF is used to obtain flux-rope parameters to model realistic CMEs within AWSoM using different flux-rope configurations.

In this work supported by the NSF SWQU and LRAC programs, we use an ensemble of solar wind backgrounds to obtain the best solar wind plasma environments into which CMEs can be launched. We vary the flux-rope parameters within a fixed range and obtain an ensemble of CME simulations to match the model reconstructed results with remote coronagraph observations near the Sun (LASCO C2/C3 and STEREO COR1/COR2) as well as with in-situ observations of solar wind plasma at 1 au. The ensemble modeling is a step forward towards improving the accuracy of the tools that provide flux-rope parameter estimates as well as the uncertainty quantification of CME modeling.

How to cite: Sachdeva, N., Toth, G., Manchester, W., van der Holst, B., Jivani, A., and Chen, H.: Ensemble modeling of CMEs to reconstruct remote and in-situ observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8641, https://doi.org/10.5194/egusphere-egu23-8641, 2023.

EGU23-8687 | ECS | Orals | ST1.6 | ST Division Outstanding Early Career Scientist Award Lecture

On the evolutionary aspects of solar coronal holes 

Stephan G. Heinemann

Coronal holes (CH) are large, long-lived structures commonly observed in the solar corona as regions of reduced emission in EUV and X-ray wavelengths. They feature a characteristic open magnetic field configuration along which ionized electrons and atoms are accelerated into the interplanetary space. The resulting outflowing plasma is called high seed solar wind stream (HSS; see Cranmer 2009 and references therein). These HSSs are the major cause of minor to moderate geomagnetic activity at Earth (see Richardson 2018 and references therein).

To be able to predict the arrival and impact of those disturbances accurately, their origin and evolution need to be studied in detail. And to do so, it is imperative that CHs are accurately and reliably extracted, thus leading to the development of the Collection of Analysis Tools for Coronal Holes (CATCH). By using the intensity gradient across the CH boundary, it is possible to robustly extract CHs whose properties can then be analyzed. We find that the area of long-living CHs generally evolves by growing to a maximum before decaying. However, the associated magnetic field does not evolve equally. Depending on the CH, we find a correlation, an anti-correlation or even no correlation over the course of its lifetime. Therefore, we believe that the evolution of a CHs magnetic field is primarily driven by the large-scale connectivity changes in the Sun's global magnetic field. Further, we find that the plasma properties within CHs show a significant center to boundary gradient, which may justify the distance-to-boundary parameter used in some solar wind modeling.

To study the evolution of CHs in detail, a 360° view of the Sun is necessary; however, the magnetic far-side of the Sun still eludes. The few snapshots with Solar Orbiter provide only a fragmented picture of the magnetic field on the solar far-side. We found that by using EUV observations of the transition region (specifically using Stereo) it is possible to estimate the magnetic field density of CHs on the solar far side. In addition, we are currently investigating the incorporation of helioseismic observations into synoptic magnetograms to generate a maps that show the magnetic field of the whole Sun at a given time.

How to cite: Heinemann, S. G.: On the evolutionary aspects of solar coronal holes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8687, https://doi.org/10.5194/egusphere-egu23-8687, 2023.

EGU23-9486 | ECS | Orals | ST1.6

The fast component of the solar wind: origins, correlations and modeling with EUHFORIA 

Evangelia Samara, Jasmina Magdalenic, Luciano Rodriguez, Stefaan Poedts, Manolis K. Georgoulis, Rui F. Pinto, Charles N. Arge, Stephan G. Heinemann, and Stefan J. Hofmeister

It is widely known that the fast solar wind originates mainly from coronal holes (CHs) in the solar corona. Associations between the CH characteristics and the properties of the fast solar wind in situ have been studied throughout the years from different authors leading to diverse degrees of correlation (Nolte et al. 1976; Vršnak et al. 2007; Karachik et al. 2011; Rotter et al. 2012a; Hofmeister et al. 2018; Heinemann et al. 2020). In this work, we introduce and quantify the geometrical complexity of CHs, a parameter that has been neglected so far in similar studies. For a particular CH sample, we explore how complexity affects the peak speed of the fast solar wind at Earth and its association with other CH properties. We further compare observations of fast solar wind at Earth with forecasts from EUHFORIA. We evaluate our results, and present the efforts and restrictions we encounter towards improving our prediction capabilities by exploiting recent PSP observations.

 

How to cite: Samara, E., Magdalenic, J., Rodriguez, L., Poedts, S., Georgoulis, M. K., Pinto, R. F., Arge, C. N., Heinemann, S. G., and Hofmeister, S. J.: The fast component of the solar wind: origins, correlations and modeling with EUHFORIA, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9486, https://doi.org/10.5194/egusphere-egu23-9486, 2023.

EGU23-9898 | ECS | Posters on site | ST1.6

Tracking the evolution of spheromak flux ropes in ambient interplanetary magnetic field and plasma environments. 

Eleanna Asvestari, Tobias Rindlisbacher, Jens Pomoell, Emilia Kilpua, and Ranadeep Sarkar

Interplanetary magnetic clouds with flux rope structures are an essential ingredient of space weather models. The main aim is to reconstruct their magnetic field topology and plasma properties and track their evolution in space and time. This has led to the implementation of a variety of flux rope configurations in magnetohydrodynamic models, with spheromak, modified spheromak, and more general toroidal flux ropes being commonly used.  

The spheromak implementation in EUHFORIA (EUropean Heliospheric FORecasting Information Asset) brought to light different manifestations in the simulation domain of a phenomenon called the spheromak tilting (instability). The latter is caused by a torque that is exerted on the spheromak when its magnetic moment forms an angle with the ambient field. The torque forces the spheromak to rotate until it reaches a state of reduced magnetic potential energy. This is a simplified description of the fact that the Lorentz force exerted by the ambient magnetic field on the toroidal currents in the spheromak has in general a rotational component, resulting in a net-torque. As not only spheromaks but also other types of flux ropes carry toroidal currents, these should experience a torque as well. To what extent it affects their evolution is a matter of a game of forces. Being thus able to track the evolution (the position, orientation, etc.) of flux ropes is crucial. 

We have developed a tool to perform such a tracking for the spheromak implementation in EUHFORIA. The tool uses magnetic field and plasma threshold criteria to locate the spheromak and estimate its magnetic moment. It was originally developed and applied to spheromaks inserted in synthetic uniform ambient plasma and unipolar ambient fields that are realistic only locally along the spheromak trajectories. Since its initial development, the tool has been further improved and made capable of dealing with more realistic ambient field scenarios, containing current sheets and high-speed streams. 

How to cite: Asvestari, E., Rindlisbacher, T., Pomoell, J., Kilpua, E., and Sarkar, R.: Tracking the evolution of spheromak flux ropes in ambient interplanetary magnetic field and plasma environments., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9898, https://doi.org/10.5194/egusphere-egu23-9898, 2023.

EGU23-9944 | Orals | ST1.6

Solar wind originating from the small coronal holes  

Jasmina Magdalenic, Senthamizh Pavai Valliappan, and Luciano Rodriguez

Observations of the solar wind at the close to the Sun distances by the Parker Solar Probe (PSP) show most of the time very strongly variable solar wind plasma characteristics. Inspecting the PSP observations during first ten perihelion, together with this large variability, we have also found a significant number of intervals of enhanced solar wind velocity appearing simultaneously with the decrease of the solar wind density, which indicates that this solar wind is originating from the coronal holes. However, out of thirty such intervals only few of them show velocity above 500 km/s. Majority of the identified wind flows have velocity of only about 400 km/s indicating that this solar wind will not be clearly distinguished as a flow when observed at 1 au distances. Employing the magnetic connectivity tool (developed by ESA’s MADAWG group) to associate the solar wind observed by the PSP with their source regions on the Sun, we identified the sources of that enhanced solar wind observed by the PSP to be the small coronal holes.

In this study we present the characteristics of a solar wind flows originating from such small coronal holes at close to the Sun distances and compare them with the characteristics of the fast solar wind originating from the large coronal holes. We also discuss on the possible reasons why we do not find more intervals of the fast solar wind in the PSP observations and compare the characteristics of solar wind observed at close to the Sun distances and at 1 au.

How to cite: Magdalenic, J., Valliappan, S. P., and Rodriguez, L.: Solar wind originating from the small coronal holes , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9944, https://doi.org/10.5194/egusphere-egu23-9944, 2023.

EGU23-12917 | ECS | Posters on site | ST1.6

Probing the solar corona with Doppler and range measurements of the spacecraft BepiColombo 

Irene Doria, Paolo Cappuccio, and Luciano Iess

The Mercury Orbiter Radio-science Experiment (MORE), onboard the ESA-JAXA mission BepiColombo, is dedicated to the study of Mercury’s interior structure and rotational state, and to fundamental physics tests. The MORE radiotracking system relies on a multi-frequency radio link: the onboard Deep Space Transponder receives an uplink in X-band and retransmits it back coherently in X- and Ka-band, the Ka-band transponder allows to establish a two-way link in Ka-band.

During the cruise phase, BepiColombo experienced four superior solar conjunctions. These periods, spanning for 15 days centered about the minimum impact parameter of the radio path between the spacecraft and the Earth, are exploited for tests of relativistic delay and Doppler shift. Thanks to the multi-frequency link the signal due to the solar corona plasma can be isolated through precise calibrations, exploiting the dispersive nature of the plasma1,2. This allows MORE to remove the plasma noise from the Doppler and range data in order to perform the fundamental physics test, but also to characterize the inner solar corona.

In this work we focus on the analysis of the data from the first (10th-24th March 2021) and second (29th January - 12th February 2022) solar conjunction experiments to characterize the properties of the solar wind.

For each radiotracking pass the power spectral density of Doppler measurements is compared with the expected power spectral index of a Kolmogorov turbulence (f-2/3)3.

Solar corona plasma data are also used to localize the plasma structures of the solar corona along the line of sight by means of cross-correlations between uplink and downlink time series of the plasma content obtained from Doppler data. This allows us to analyze in more detail large solar phenomena, such as coronal mass ejections.

Exploiting the collected open-loop recordings at high frequency (4 kHz), the solar wind velocity can be estimated assuming a theoretical model for the intensity spectrum4. The intensity timeseries are used to fit theoretical spectrum parameters (amplitude, velocity, axial ratio, inner scale of turbulence and power law index), characterizing the solar wind in the vicinity of the Sun.   

Finally, the range data set allows us to retrieve the total electron content along the radio path. This absolute measurement is used to adjust models of the solar wind density beyond four solar radii.

 

1 Bertotti et al, “Doppler tracking of spacecraft with multi-frequency links”,Astronomy and Astrophysics 269, 608-616, 1993

2 Bertotti et al, “A test of general relativity using radio links with the Cassini spacecraft”, Nature 425, 374-376, 2003

3 R. Woo and J.W. Armstrong, “Spacecraft Radio Scattering Observations of the Power Spectrum of Electron Density Fluctuations in the Solar Wind”, Journal of Geophysical Research 84, no. Al2, 1979

4 S. L. Scott, W. A. Coles and G. Bourgois, “Solar wind observations near the sun using interplanetary scintillation”, Astronomy and Astrophysics 123, 207-215, 1983

How to cite: Doria, I., Cappuccio, P., and Iess, L.: Probing the solar corona with Doppler and range measurements of the spacecraft BepiColombo, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12917, https://doi.org/10.5194/egusphere-egu23-12917, 2023.

EGU23-13296 | ECS | Posters virtual | ST1.6

Implementing a toroidal flux rope model in EUHFORIA and assessing its performance in predicting CME magnetic-field at 1 AU 

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 field 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. We track the evolution of the flux-rope up to 1 AU and assess the model results with the observed in situ profile of the associated CME.  This work is an important step forward in developing a realistic CME model that can be used for reliable space weather forecasting.

How to cite: Sarkar, R., Pomoell, J., Kilpua, E., and Asvestari, E.: Implementing a toroidal flux rope model in EUHFORIA and assessing its performance in predicting CME magnetic-field at 1 AU, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13296, https://doi.org/10.5194/egusphere-egu23-13296, 2023.

EGU23-15636 | ECS | Posters on site | ST1.6

On the validation of the rotation procedure from HEE to MFA reference frame in presence of Alfvén waves in the interplanetary medium 

Giuseppina Carnevale, Mauro Regi, Patrizia Francia, and Stefania Lepidi

Alfvén waves play an important role in the stability, heating, and transport of magnetized plasmas. They are found to be ubiquitous in the solar wind, mainly propagating outward from the Sun, especially in high-speed streams emanating from coronal holes. When high-speed streams impinge on the Earth’s magnetosphere, the impact of Alfvénic fluctuations can cause magnetic reconnection between the intermittent southward IMF and the Geomagnetic field, leading to energy injection from solar wind into the Earth’s magnetosphere. In this work, we tested a rotation procedure from the
Heliocentric Earth Ecliptic (HEE) to the Mean-Field Aligned (MFA) reference frame, identified by means of the Empirical Mode Decomposition (EMD), of both solar wind velocity and interplanetary magnetic field at 1 AU. Our aim is to check the reliability of the method and its limitations in identifying Alfvénic fluctuations through the spectral analysis of time series in the MFA reference frame. With this procedure, we studied the fluctuations in the main-field-aligned direction and those in the orthogonal plane to the main field. To highlight the peculiarities of each case of study and be able to better identify Alfvén waves when applying this procedure to real data, we reproduced the magnetic and velocity fields of a typical corotating high-speed stream. We tested the procedure in several cases, by adding the presence of Alfvén waves and noise. We performed the spectral analysis of the MFA component of both magnetic and velocity fields to define the power related to the two main directions: the one aligned to the ambient magnetic field and the one orthogonal to it. The efficiency of the procedure and the result’s reliability are supported by Monte Carlo tests. The method is as well applied to a real case represented by a selected corotating solar wind stream. The results are also compared with those obtained by using the Elsässer variables to analyze the Alfvénicity of fluctuations via the cross-helicity, which is related to the degree of correlation between the solar wind velocity and the magnetic field fluctuations.

How to cite: Carnevale, G., Regi, M., Francia, P., and Lepidi, S.: On the validation of the rotation procedure from HEE to MFA reference frame in presence of Alfvén waves in the interplanetary medium, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15636, https://doi.org/10.5194/egusphere-egu23-15636, 2023.

Coronal Mass Ejections (CMEs) carry large amounts of magnetized plasma into the heliosphere at very high speeds. Their interplanetary counterparts, or Interplanetary CMEs (ICMEs), create adverse space weather conditions around planets. These interplanetary structures have the potential to cause hazardous space weather and impact space- and ground-based technologies on Earth. At CESSI we have developed a 3D magnetohydrodynamic STORM Interaction (CESSI-STORMI) module to simulate the interactions between ICMEs and planets with and without a global magnetosphere. In this talk, I shall discuss our data-driven simulations to assess ICME impact on the Earth’s magnetosphere and  present a methodology to estimate their geo-effectiveness. We validate this module with observations and find a good match with the observed values of the Dst index for past events. In addition, we also present a qualitative study of the global magnetosphere under the influence of ICMEs. Our work allows us to estimate the severity of geomagnetic storms based on early, data-driven inputs of ICME flux rope profiles gleaned from near-Sun or in-situ observations. Thus our work has the potential to significantly extend the time window for predicting the severity of geomagnetic storms - which remains a grand challenge in heliophysics.

How to cite: Roy, S. and Nandy, D.: A magnetohydrodynamic modelling approach to simulate CME-forced planetary magnetospheres and predict geomagnetic impacts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16801, https://doi.org/10.5194/egusphere-egu23-16801, 2023.

EGU23-17122 | ECS | Posters on site | ST1.6

Modelling the propagation of flux ropes in the coronal model COCONUT 

luis linan, Florian Regnault, Barbara Perri, Michaela Brchnelova, Blazej Kuzma, Andrea Lani, and Stefaan Poedts
Some space weather forecasting tools, such as the EUropean Heliosphere FORecasting Information Asset (EUHFORIA), consist of two parts. The first is a semi-empirical coronal model used to create the background solar wind, and the second is a heliospheric model in which coronal mass ejections (CMEs) are injected through the inner boundary located at 0.1 AU. In these models, the inserted CME does not interact with the solar wind before the inner boundary.
 
To take this interaction into account and provide a more realistic description of CMEs at 0.1 AU. We studied the propagation of flux ropes from the solar surface to 0.1 AU in a full magnetohydrodynamic coronal model called COCONUT (COolfluid COroNal UnsTructured). The CMEs were modeled using the modified Titov-Démoulin model (TDm) of flux rope. We tracked the evolution of twenty four different twisted flux ropes within realistic corona configurations reconstructed by COCONUT from the GONG magnetic maps of both minimum and maximum solar activity. All CMEs are identical except for their net initial current.
 
Our results reflect dynamic expected by the standard flare model, such as presence of post-flare loops and the pinching of the CME's legs. However, the shape of the CME varies greatly depending on whether the solar wind corresponds to a minimum or a maximum activity, highlighting the crucial role of the solar wind in determining the geometry of CMEs. Once the flux ropes reach 0.1 AU, their thermodynamic and magnetic properties are extracted. We found that, for the two solar wind configurations, the synthetic profiles obtained are consistent with those that satellites could measured. Moreover, simple relationships are emphasised between the net initial current of flux ropes and the shape of the different synthetic profiles. 
 
Finally, using this CME description, the boundary conditions imposed on EUHFORIA (or other heliospheric models) should be more accurate than those provided by an independent CME model and therefore lead to more realistic forecasts.​
 

How to cite: linan, L., Regnault, F., Perri, B., Brchnelova, M., Kuzma, B., Lani, A., and Poedts, S.: Modelling the propagation of flux ropes in the coronal model COCONUT, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17122, https://doi.org/10.5194/egusphere-egu23-17122, 2023.

EGU23-2002 | PICO | ST1.8 | Highlight

Data-driven simulation of the coronal mass ejection of October 28 2021 

Brigitte Schmieder, Jin Han Guo, Pooja Devi, Ramesh Chandra, Yang Guo, Pen Feng Chen, and Stefaan Poedts

The event of October 28 2021 was very geoeffective with particles accelerated to high energies resulting in ground level enhancements (GLEs). It is important to understand the scenario leading to such energetic particle acceleration which can be done by studying the origin of this event from the Sun to the Earth through the heliosphere.  The acceleration of particles was justified by two acceleration processes, one due to the flare during the impulsive phase, and the second by the coronal mass ejection (CME), which prolonged the low level proton emission (Zhang, Gan et al 2022, Klein et al 2022).

The first step of our study  was to understand the relationship between the  flare, the EUV wave and the CME  using the SDO, STEREO- A/COR1 and SOHO/LASCO observations (Devi et al 2022).  The second step was to model the CME (Guo et al 2023).

We found that a fast-mode EUV wave front propagates ahead  the CME front. The eruption was modeled by a flux rope using the Regularized  Biot-Savart Laws in a data-driven background obtained with HMI magnetograms. The CME was well recovered with its three components and the shock fitted with the observations.  We plan to study the evolution of  this flux rope in the solar wind by using  EUHFORIA.

How to cite: Schmieder, B., Guo, J. H., Devi, P., Chandra, R., Guo, Y., Chen, P. F., and Poedts, S.: Data-driven simulation of the coronal mass ejection of October 28 2021, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2002, https://doi.org/10.5194/egusphere-egu23-2002, 2023.

EGU23-3475 | ECS | PICO | ST1.8

Self-consistent modelling of nanoflares: generation of heating and thermodynamic response in 3D MHD 

Jack Reid, Craig D. Johnston, James Threlfall, and Alan W. Hood

Resolving thermodynamic transport in three-dimensional models of stratified coronal loops is a long-standing challenge that limits progress in solving the coronal heating problem.
Since three-dimensional thermal conduction in MHD has been computationally too expensive to resolve the steep temperature gradients in the transition region, two simpler approaches have been adopted: one-dimensional, field-aligned models following the thermal response to imposed forms of heating, and three-dimensional MHD models that produce the forms of Ohmic and viscous heating self-consistently but cannot consider the consequent thermodynamic response.
Now, using a novel numerical technique, TRAC, we can resolve energetic transport in the transition region in fully three-dimensional MHD models.
In a model of a multi-stranded coronal loop in a curved arcade, we investigate the heating produced in an 'avalanche'-like process.
In such, a chain reaction of reconnection-induced local events occurs, with each event disturbing wider plasma and triggering other processes, such as shocks, jets, and turbulence, that generate heating, which we analyse with particular attention to the spatio-temporal distribution of nanoflares.
At the same time, we treat the thermodynamic response of the plasma self-consistently, and study the evolving temperature profiles.
Avalanches successfully propagate in curved arcades and appear capable of maintaining a hot corona with realistic temperatures and densities in heated loops.
One novelty of interest lies in `campfire'-like events, with simultaneous reconnection events at disjoint sites along coronal strands, akin to recent results from Solar Orbiter.

How to cite: Reid, J., Johnston, C. D., Threlfall, J., and Hood, A. W.: Self-consistent modelling of nanoflares: generation of heating and thermodynamic response in 3D MHD, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3475, https://doi.org/10.5194/egusphere-egu23-3475, 2023.

EGU23-4394 | ECS | PICO | ST1.8

Data-driven simulation of a magnetic flux rope in the heliosphere: from birth to death 

Jinhan Guo, Yiwei Ni, Yang Guo, Chun Xia, Pengfei Chen, Stefaan Poedts, and Brigitte Schmieder

Magnetic flux ropes are bundles of twisted magnetic field lines produced by the internal flowing electric currents, which are regarded as one of the basic and pivot structures in solar and space physics. Statistics showed that about 90% of the erupting filaments are supported by flux ropes, implying that the majority of solar eruptions are driven by flux ropes. Moreover, the post-eruption flux ropes in interplanetary space, called interplanetary magnetic clouds, are the major drivers of geomagnetic storms. As such, a numerical model that is capable of capturing the whole process of the flux rope from its birth to its death or eruption is certainly crucial for predicting adverse space weather events. Recently, we develop a data-driven model combined with the observed vector magnetic field and velocity field, which reproduces the formation and confined eruption of an observed flux rope. We find that the photospheric shearing and converging plasma flows play a critical role in the flux rope formation, and the magnetic configuration is analogous to the “tether-cutting”  reconnection illustration. Regarding the confined eruption, we find that the deformation of the flux rope during the eruption causes an increase in downward tension force, which suppresses the ascendence of the flux rope. This finding might shed light on why many large-angle rotation events are always confined and torus unstable.

How to cite: Guo, J., Ni, Y., Guo, Y., Xia, C., Chen, P., Poedts, S., and Schmieder, B.: Data-driven simulation of a magnetic flux rope in the heliosphere: from birth to death, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4394, https://doi.org/10.5194/egusphere-egu23-4394, 2023.

EGU23-7415 | ECS | PICO | ST1.8

Studying ionic composition in open field regions using a 16 moments multi-species fluid model 

Paul Lomazzi, Victor Réville, Alexis Rouillard, and Pascal Petit

Spectroscopic observations of the solar atmosphere reveal regions of the solar corona that are enriched in the abundance of heavy element with low-first ionisation potential (examples of low ‘FIP’ i.e. with <10 eV are Fe, Mg) relative to photospheric abundances. This enhancement in the abundance of low-FIP elements by a factor of three or four, called the ‘FIP effect’, is still not well understood. Moreover enriched abundances of low-FIP elements are also observed in the slow solar wind, which could give us more insights on its origins. An inverse-FIP effect corresponding to a decreased abundance of low-FIP elements has been measured in the atmosphere of M-type stars.

Turbulent mixing of the chromosphere combined with the ponderomotive force caused by Alfvén waves propagating in these atmosphere could give a mechanism that might explain the FIP effect. Diffusive theories including the thermal force exerted on the ions due to a collision frequency gradient has also a role to play on minor ion extraction from the chromosphere.  Our goal is to study and compare these effects using  ISAM, a new 1D 16 moments multi-fluid model taking into account collisional effects of the different heavy ions. In this work we use profiles from 3 different solar wind types simulated using ISAM in which we propagate Alfvén waves with a Shell Model of Alfvén-wave turbulence. We then compare the FIP bias obtained from these 3 types of wind.

This work has been funded by the ERC SLOWS SOURCE DLV 819189

How to cite: Lomazzi, P., Réville, V., Rouillard, A., and Petit, P.: Studying ionic composition in open field regions using a 16 moments multi-species fluid model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7415, https://doi.org/10.5194/egusphere-egu23-7415, 2023.

Three-dimensional (3-d) magnetohydrodynamics (MHD) modeling is a key method for studying the interplanetary solar wind. In this article, In this paper, we introduce a new 3-d MHD solar wind model driven by the self-consistent boundary condition obtained from multiple observations and Artificial Neural Network (ANN) machine learning technique. At the inner boundary, the magnetic field is derived using the magnetogram and potential field source surface extrapolation; the electron density is derived from the polarized brightness (pB) observations, the velocity can be deduced by an ANN using both the magnetogram and pB observations, and the temperature is derived from the magnetic field and electron density by a self-consistent method. Then, the 3-d interplanetary solar wind from CR2057 to CR2062 are modeled by the new model with the self-consistent boundary conditions. The modeling results present various observational characteristics at different latitudes, and are in good agreement with both the OMNI and Ulysses observations.

How to cite: Shen, F., Yang, Y., and Feng, X.: 3D MHD Modeling of Interplanetary Solar Wind Using Self-Consistent Boundary Condition Obtained from Multiple Observations and Machine Learning, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10143, https://doi.org/10.5194/egusphere-egu23-10143, 2023.

EGU23-10557 | ECS | PICO | ST1.8

Rotation and Confined Eruption of a Double Flux-Rope System 

Xiaomeng Zhang, Jinhan Guo, Yang Guo, Mingde Ding, and Rony Keppens

We perform a data-constrained simulation with the zero-β assumption to study the mechanisms of strong rotation and failed eruption of a filament in active region 11474 on 2012 May 5 observed by Solar Dynamics Observatory and Solar Terrestrial Relations Observatory. The initial magnetic field is provided by nonlinear force-free field extrapolation, which is reconstructed by the regularized Biot-Savart laws and magnetofrictional method. Our simulation reproduces most observational features very well, e.g., the filament large-angle rotation of about 130°, the confined eruption and the flare ribbons, allowing us to analyze the underlying physical processes behind observations. We discover two flux ropes in the sigmoid system, an upper flux rope (MFR1) and a lower flux rope (MFR2), which correspond to the filament and hot channel in observations, respectively. Both flux ropes undergo confined eruptions. MFR2 grows by tether-cutting reconnection during the eruption. The rotation of MFR1 is related to the shear-field component along the axis. Moreover, we find that the magnetic tension force is the cause of the confined eruption of MFR1. We also suggest that the mutual interaction between MFR1 and MFR2 contributes to the large-angle rotation and the eruption failure. In addition, we calculate the temporal evolution of the twist and writhe of MFR1, which may be a hint of probably existing reversal rotation.

How to cite: Zhang, X., Guo, J., Guo, Y., Ding, M., and Keppens, R.: Rotation and Confined Eruption of a Double Flux-Rope System, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10557, https://doi.org/10.5194/egusphere-egu23-10557, 2023.

According to the standard scenario of plasma emission, the escaping radiations are generated from the nonlinear development of the kinetic bump-on-tail instability, by a single beam of energetic electrons interacting with an overdense plasma. The primarily-excited beam-Langmuir mode and its further scattering over ion-related disturbances are suggested to be critical to the radiation process. Yet, non-beam distributions of energetic electrons, such as the ring (or ring-beam), DGH, loss-cone, horseshoe-like, etc., also exist broadly in space and astrophysical plasmas. They may drive wave modes distinct from those in the beam-plasma system. The corresponding radiation process could be distinct from that described by the standard scenario. To clarify this, we conducted particle-in-cell simulations to investigate the nonlinear response of an overdense plasma disturbed by energetic electrons of velocity distributions (VDs) changing from beam-like to ring-like. Efficient excitations of both the fundamental (F) and harmonic (H) plasma emissions are found for all the VDs investigated here, yet the kinetic instability, the wave modes excited, and the F/H radiation process are different. Details of these differences will be overviewed in this report.

How to cite: Chen, Y.: Coherent Radiation in Overdense Plasmas Interacting with Energetic Electrons of Different Velocity Distributions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17301, https://doi.org/10.5194/egusphere-egu23-17301, 2023.

EGU23-17375 | PICO | ST1.8

Collisionless shock as a self-organized system 

Michael Gedalin

A collisionless shock is a self-organized system, the main task of which is fast and stable transfer of the conserved quantities, that is, mass, momentum, and energy, from one side, upstream, to the other side, downstream, while adding entropy. ”Fast” means that the transfer occurs at the scales
much smaller than the MHD scales. ”Stable” means that there are not disruptions of substantial changes on average, except those which are caused
by variations of ambient conditions. In this approach the developing shock structure is the one which ensures this transfer. This means, that if the
transfer stability is not possible without an overshoot, an overshoot has to be formed. If it is not possible without rippling, rippling will develop. Since
ions are the main carriers of these conserved quantities, it is ions which are responsible for developing the structure and it is ions which have to
most strongly affected by it. In particular, we show that overshoot plays an important role regulating ion reflection so that the shock becomes stable.

How to cite: Gedalin, M.: Collisionless shock as a self-organized system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17375, https://doi.org/10.5194/egusphere-egu23-17375, 2023.

EGU23-17380 | ECS | PICO | ST1.8

Electron-cyclotron emission model of solar radio zebras with high gyro-harmonic numbers 

Jan Benáček and Marian Karlický

Solar radio zebras detected as fine structures of Type IV radio bursts help to diagnose the coronal plasma at kinetic micro-scales. One of the models of the radio zebras is the electron-cyclotron maser instability based on a double plasma resonance at gyro-harmonics of the electron cyclotron frequency when ωpe > ωce. Though the gyro-harmonic numbers estimated for zebra observations are very high, in some cases exceeding 100, it is still uncertain how the instability can grow and generate zebra stripes for them. To investigate the instability evolution, we studied its growth and saturation by utilizing analytical calculations and particle-in-cell simulations. We found that the growth rates and saturation energies as functions of the cyclotron-to-plasma frequency ratio form a profile that peaks approximately at the integer harmonics of the cyclotron frequency. Nonetheless, the peaks shift to lower frequencies with increasing the plasma loss-cone temperature, and they broaden and decrease with increasing the gyro-harmonic number. These results suggest that emissions for very high gyro-harmonic numbers should not be formed. Hence, to explain the detected high gyro-harmonic numbers of one hundred, we also investigated the growth rates as a function of the loss-cone angle and found that distributions with very  high loss-cone angles can interpret the observations. We proposed that such large loss-cone angles can be generated in magnetic loops with small magnetic field gradients or below an X-point of the magnetic reconnection. 

How to cite: Benáček, J. and Karlický, M.: Electron-cyclotron emission model of solar radio zebras with high gyro-harmonic numbers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17380, https://doi.org/10.5194/egusphere-egu23-17380, 2023.

EGU23-7 | ECS | Orals | ST1.10

Modeling the 2020 November 29 solar energetic particle event using EUHFORIA and iPATH models 

Zheyi Ding, Nicolas Wijsen, Gang Li, and Stefaan Poedts

We present the implementation of a coupling between EUropean Heliospheric FORcasting Information Asset (EUHFORIA) and improved Particle Acceleration and Transport in the Heliosphere (iPATH) models. In this work, we simulate the widespread solar energetic particle (SEP) event of 2020 November 29 and compare the simulated time-intensity profiles with measurements at Parker Solar Probe (PSP), the Solar Terrestrial Relations Observatory (STEREO)-A, SOlar and Heliospheric Observatory (SOHO), and Solar Orbiter (SolO). We examined the temporal evolution of shock parameters and particle fluxes during this event and we find that adopting a realistic solar wind background can significantly impact the expansion of the shock and, consequently, the shock parameters. Time-intensity profiles with an energetic storm particle event at PSP are well reproduced from the simulations. In addition, the simulated and observed time-intensity profiles of protons show a similar two-phase enhancement at STA. These results illustrate that modeling a shock using a realistic solar wind is crucial in determining the characteristics of SEP events. The decay phase of the modeled time-intensity profiles at Earth is in good agreement with the observations, indicating the importance of perpendicular diffusion in widespread SEP events. Taking into account the possible large curved magnetic field line connecting to SolO, the modeled time-intensity profiles show a good agreement with the observation. We suggest that the broadly distorted magnetic field lines, which are due to a stream interaction region, may be a key factor in understanding the observed SEPs at SolO.

How to cite: Ding, Z., Wijsen, N., Li, G., and Poedts, S.: Modeling the 2020 November 29 solar energetic particle event using EUHFORIA and iPATH models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7, https://doi.org/10.5194/egusphere-egu23-7, 2023.

EGU23-1741 | ECS | Posters virtual | ST1.10

Energy Spectrum of Solar Energetic Electron Events Over 25 Years 

Wen Wang, Linghua Wang, Zixuan Liu, Samuel Krucker, and Robert F. Wimmer-Schweingruber

Solar Energetic electron (SEE) events are the most common solar particle acceleration phenomenon detected in situ in the interplanetary medium and the energy spectrum of SEE events carries crucial information on the acceleration and/or transport processes of SEEs. In our research, we investigate the peak flux energy spectrum of 458 SEE events with a clear velocity dispersion detected at energies from ≤ 4.2 keV to ≥ 108 keV by Wind/3DP from 1994 December through 2019 December, utilizing a pan-spectrum fitting method. According to the fitted spectral parameters, these 458 events are self-consistently classified into five spectral shapes: 304 DDPL events, 32 UDPL events, 23 SPL events, 44 ER events and 55 LP events. The DDPL events can be further divided in to two types: 231 EB≥20 keV DDPL events and 73 EB<20 keV DDPL events, since the distribution of break energy EB exhibits a primary peak around 60 keV and a secondary peak around 7 keV, separated by a dip at ~20 keV. The EB≥20 keV (EB<20 keV) DDPL events exhibit a power-law spectral index of 2.0+0.2-0.2(2.1+0.3-0.3) (values shown in a form of A+B-C means the median value with the first and the third quartiles) at energies below EB=5.6+2.3-2.4 keV (60+23-12 keV) and index of 3.3+0.5-0.3 (3.9+0.6-0.7) at energies above.The UDPL events have a spectral index of 3.0+0.3-0.3 at energies below EB=5.1+4.2-1.8 keV and index of 2.2+0.2-0.3 at energies above. The SPL events shows a spectral index of 2.8+0.5-0.2. The ER events exhibit a spectral index 1.9+0.3-0.3 at energies below Ec=30+19-10 keV. The six spectrum types also behave differently in the relationship between spectral parameters and in solar cycle variations. Furthermore, propagation effects in the IPM from the Sun to 1 AU appear to have no obvious influence on the spectral shape of most SEE events. These results suggest that the formation of SEE events can involve complex processes/sources.

How to cite: Wang, W., Wang, L., Liu, Z., Krucker, S., and Wimmer-Schweingruber, R. F.: Energy Spectrum of Solar Energetic Electron Events Over 25 Years, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1741, https://doi.org/10.5194/egusphere-egu23-1741, 2023.

EGU23-2518 | ECS | Orals | ST1.10

Solar activity relations in energetic electron events measured by the MESSENGER mission 

Laura Rodríguez-García, Laura Balmaceda, Raúl Gómez-Herrero, Athanasios Kouloumvakos, Nina Dresing, David Lario, Yannis Zouganelis, Annamaria Fedeli, Francisco Espinosa Lara, Ignacio Cernuda, George Ho, Robert Wimmer-Schweingruber, and Javier Rodríguez-Pacheco

We perform a statistical study of the relations between the properties of solar energetic electron (SEE) events measured by the MESSENGER mission from 2010 to 2015 and the parameters of the respective parent solar activity phenomena to identify the potential correlations between them. During the time of analysis MESSENGER heliocentric distance varied between 0.31 and 0.47 au.

The main conclusion of the study is as follows. For this particular sample of events, with a majority of SEE events being widespread in heliolongitude and displaying relativistic electron intensity enhancements, a shock-related acceleration mechanism might be relevant in the acceleration of near-relativistic electrons. This conclusion is mainly based on three results. (1) The high and significant correlation found between the SEE peak intensities and the shock speed. (2) The ∼4 orders of magnitude in the SEE peak intensities for the same CME-driven shock speed that might be related to the presence of supra-thermal seed population that made local shock acceleration more efficient. (3) The asymmetry to the east of the range of connection angles (CAs) for which the SEE events present higher peak intensities and higher correlations with the solar activity, which might be related to the evolution of the magnetic field connection to the shock front. We note that the CA is defined as the angular distance between the footpoint of the magnetic field connecting to the spacecraft and the longitude of the source region.

How to cite: Rodríguez-García, L., Balmaceda, L., Gómez-Herrero, R., Kouloumvakos, A., Dresing, N., Lario, D., Zouganelis, Y., Fedeli, A., Espinosa Lara, F., Cernuda, I., Ho, G., Wimmer-Schweingruber, R., and Rodríguez-Pacheco, J.: Solar activity relations in energetic electron events measured by the MESSENGER mission, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2518, https://doi.org/10.5194/egusphere-egu23-2518, 2023.

EGU23-4398 | ECS | Posters on site | ST1.10

Analysis of the Energetic Storm Particle events of 6-7 September 2017 

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

Most of the energetic particles observed in the heliosphere are accelerated from a few keV up to MeV by shock fronts which are associated with the transit of coronal mass ejections (CMEs). The study of energetic storm particle events (ESP) can be very helpful for the investigation of the acceleration processes of particles at the shocks. We considered two ESP events occurring 6-7 September, 2017. The data used to study kinetic energy spectra are proton flux enhancements provided by WIND and ACE spacecraft that are both at the Lagrangian point L1, close to 1 AU along the Sun-Earth direction. The energy ranges are from 70 keV to 70 MeV and from 40 keV to 4.8 MeV, respectively. In order to broaden the range of the analyzed energies, we combine these data with the proton fluxes from SoHO spacecraft, also located at L1, which detects particles with energies from 1.3 MeV to 130 MeV. We used the Weibull functional form, the double power law and the Ellison-Ramaty form to fit the observed spectra. The implications of the obtained results for particle acceleration are discussed, taking also into account the properties of the shocks and of the magnetic turbulence in their surroundings.

This research has been carried out in the framework of the CAESAR 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 prototype of scientific data centre for Space Weather.”

How to cite: Chiappetta, F., Laurenza, M., Lepreti, F., Benella, S., and Consolini, G.: Analysis of the Energetic Storm Particle events of 6-7 September 2017, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4398, https://doi.org/10.5194/egusphere-egu23-4398, 2023.

Radiation is one of the most important risks to deep space exploration programs such as manned missions to the Moon and Mars. In preparation for such programs, it requires a thorough understanding of interplanetary space weather conditions and a timely forecast of their potential effects as a baseline for the development of mitigation strategies. 

 

Radiation damage in space comes mainly from two sources, Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs). In particular, intense SEP events could result in very high doses in a short time period that may exceed the threshold to induce deterministic radiation effects and to result in severe damages to humans and equipment leading to the failure of the entire mission. SEP events with radiation hazards, despite of being rather infrequent and sporadic, are however very difficult to forecast and remain as a major challenge for space weather studies in preparation for future deep space and Mars missions.

 

Specifically speaking, the SEP radiation reaching an astronaut on a Mars may be completely different from of that detected at (or predicted for) Earth’s vicinity, including the SEP onset time, spectra evolution, radiation intensity etc. This is due to (1) the different location of Mars and connectivity to the acceleration source which allow it to have difference access to the SEP population, and (2) the different planetary environment which modifies the energy and composition of the particles due to the interactions of primary particles with the atmosphere/regolith and the generation of secondaries. The synergistic analysis and modeling of these two processes are particularly important to understand and eventually forecast SEPs and their radiation effects on Mars in preparation for mitigating their potential hazardous effects.  We also emphasize the utmost importance of utilizing multi-spacecraft particle measurements at Mars and also other heliospheric locations to better understand such extreme events and their radiation effects for future deep space explorers.

How to cite: Guo, J.: The Impact of Solar Energetic Particles at Mars’ radiation environment: A synergistic approach combining measurements and Modeling efforts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5292, https://doi.org/10.5194/egusphere-egu23-5292, 2023.

EGU23-7171 | Posters on site | ST1.10

Modelling of atmospheric transport of SEP-induced cosmogenic 10Be  using CCM SOCOL-AER2-BE 

Kseniia Golubenko, Eugene Rozanov, Gennady Kovaltsov, Mélanie Baroni, and Ilya Usoskin

10Be is a cosmogenic isotope continuously produced in the Earth’s atmosphere by galactic cosmic rays (GCRs) and sporadically by solar energetic particles (SEPs). The long-living isotope, as measured in polar ice cores, typically with an annual resolution, serves as a proxy for long-term cosmic-ray variability, whose signal can, however, be distorted by atmospheric transport and deposition that need to be properly modelled. Atmospheric transport of 10Be depends on production, atmospheric circulation, and local orography. For an accurate physical description of the isotope's transport and deposition, we use the chemical climate model (CCM) SOCOL-AER2-BE. In combination with the production model CRAC, our model was verified using real measurements of beryllium in ice cores for Antarctic and Greenland locations. The model results agree with the measurements at the absolute level, implying that the production, decay, and lateral deposition are correctly reproduced. However, the exact time variability is not always well reproduced, particularly for the Greenland shore sites implying significant regional effects. Potentially, extreme SPEs that are orders of magnitude stronger than those observed during the recent decades can be recorded in cosmogenic isotope data, and a proper model is needed to study them. Here we present a model of the production and transport of 10Be for a major solar energetic particle event (GLE 69) and analyze the geographical pattern of the beryllium concentration.

How to cite: Golubenko, K., Rozanov, E., Kovaltsov, G., Baroni, M., and Usoskin, I.: Modelling of atmospheric transport of SEP-induced cosmogenic 10Be  using CCM SOCOL-AER2-BE, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7171, https://doi.org/10.5194/egusphere-egu23-7171, 2023.

EGU23-7905 | ECS | Orals | ST1.10 | Highlight

Development of an In-Progress Forecasting Model to Forecast Radiation Dose Rates Once a Ground-Level Enchancement has Begun 

Chris Davis, Charlotte Waterfall, Fan Lei, Silvia Dalla, Keith Ryden, Ben Clewer, and Clive Dyer

During major solar energetic particle events, radiation dose rates in Earth's atmosphere at aviation altitudes can increase by orders of magnitude relative to dose rates during quiet times in events known as Ground-Level Enhancements (GLEs). In the case of events of a scale such that they occur once every few decades, radiation dose rates could become high enough that they pose a threat to aircraft crew and electronics. It is not currently possible to predict when such an event will occur, and existing software systems are only capable of nowcasting the current atmospheric radiation dose rates using real-time data sources. However, while it is not possible to forecast when a major event will occur, it may be possible to generate forecasts for radiation dose rates once an event has been registered to have begun. The ability to provide forecasts for dose rates once a GLE has started would be vital for airlines and for pilots in any future where aircraft might be rerouted to avoid regions of high radiation, as pilots need to be able to know not just their current radiation dose rates but radiation dose rates at possible locations where their plane might be in say half an hour's time. We report on the development of a software system to do this. This 'in-progress' radiation dose rate forecasting system will be developed by integrating the FOrecasting Relativistic particles during GLE Events (FORGE) system being developed at the University of Central Lancashire with an anisotropic extension to the Models for Atmospheric Ionising Radiation Effects+ (MAIRE+) system being developed at the University of Surrey. We report on the development of both of these systems and their integration.

How to cite: Davis, C., Waterfall, C., Lei, F., Dalla, S., Ryden, K., Clewer, B., and Dyer, C.: Development of an In-Progress Forecasting Model to Forecast Radiation Dose Rates Once a Ground-Level Enchancement has Begun, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7905, https://doi.org/10.5194/egusphere-egu23-7905, 2023.

EGU23-8936 | ECS | Orals | ST1.10

Particle Energisation in a 3D Collapsing Magnetic Trap Model With a Braking Jet  

Kate Mowbray and Thomas Neukirch

Investigating the motion of charged particles in time- and space-dependent electromagnetic fields is central to many areas of space and astrophysical plasmas. Here we present results of studying the energy changes of particle orbits that are trapped in inhomogeneous and time-dependent magnetic fields with rapidly shortening field lines. These so-called collapsing magnetic trap (CMT) models can be useful to better understand the particle energisation processes occurring below the reconnection region in a solar flare. Braking jets may be associated with magnetic reconnection, for example when a sunward flow slows down as it approaches a stronger region of magnetic field. We generalise a 2D CMT model with braking jet (Borissov et al., 2016) to three dimensions and investigate the dynamics of particles in this 3D CMT model. The resulting particle orbits show a sensitive dependence of particle energies on the initial conditions of orbits, with initial pitch angles playing a particularly important role. This sensitive dependence relates to the time evolution of trapping regions that develop in the braking jet region of the CMT, ensuring that some orbits spend a significant time in the loop legs of field lines, whilst others escape these regions for the duration of the simulation. These loop leg trapped particle orbits see significantly lower energy gains than those orbits that repeatedly pass the loop top, with some of these particles even losing energy. This gives us greater insight into the importance of the curvature of collapsing loop tops for the Fermi acceleration mechanism acting on the particles. 

 

Borissov A. et al., Solar Physics 291, Issue 5, 1385 

How to cite: Mowbray, K. and Neukirch, T.: Particle Energisation in a 3D Collapsing Magnetic Trap Model With a Braking Jet , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8936, https://doi.org/10.5194/egusphere-egu23-8936, 2023.

A joint analysis approach is used to study flare signatures both in the low and higher corona. STIX, AIA and LOFAR data provide an extensive picture about different aspects of flare characteristics. Recent data by the STIX instrument complement the picture of accelerated electrons, which propagate along magnetic field lines towards the Sun. These observations are linked to the LOFAR data, which contain information about the elctrons propagating away from the Sun through the corona above the active region. Although, the active region and its thermal evolution (Differential Emission Measure (DEM) reconstruction of AIA data), flare accelerated electrons and their radio traces (LOFAR, STIX) are in principal all associated with the energy release during the flare process, they are often studied seperatly. Hence, the investigation of possible relations is part of this project. Solar magnetic fields as a binding element between low and high corona, accelerated electrons and heated flare loops are included in the analysis via a Potential Field Source Surface (PFSS) model.

How to cite: Bröse, M. and Vocks, C.: Flare-accelerated electrons and their traces in the solar corona observed by space- and ground-based instruments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9582, https://doi.org/10.5194/egusphere-egu23-9582, 2023.

EGU23-10509 | ECS | Posters on site | ST1.10

Radial Variation of Suprathermal Particles Associated with Corotating Interaction Regions 

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

The first three years of Solar Orbiter operations have enabled robust sampling of the intensity and composition of suprathermal particles within the inner heliosphere. This includes a multitude of observations of suprathermal ions associated with Corotating Interaction Regions (CIRs), with corresponding observations at 1 au with measurements from the Ultra-Low-Energy Isotope Spectrometer (ULEIS) on the Advanced Composition Explorer (ACE) mission and the Suprathermal Ion Telescope (SIT) on the Solar-Terrestrial Relations Observatory-Ahead (STEREO-A) spacecraft. Comparing observations between these spacecraft allows for a statistical view of the radial variations of CIR-associated suprathermal particles by composition in the inner heliosphere, allowing for greater insight into energetic particle transport within the inner heliosphere. This study expands on early results from Solar Orbiter and ACE to now encompass the first three years of Solar Orbiter operations, as well as include STEREO-A measurements. Comparisons to historical studies of CIR-associated energetic protons are also expanded in the survey of CIR-associated suprathermal particles from Solar Orbiter, ACE, and STEREO-A.

How to cite: Allen, R., Ho, G., Mason, G., Kouloumvakos, A., Wimmer-Schweingruber, R., and Rodríguez-Pacheco, J.: Radial Variation of Suprathermal Particles Associated with Corotating Interaction Regions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10509, https://doi.org/10.5194/egusphere-egu23-10509, 2023.

EGU23-11362 | ECS | Posters virtual | ST1.10

Solar Energetic Electron Events with a Spectral Bump 

Wenyan Li, Linghua Wang, and Wen Wang

The energy spectrum of solar energetic electron (SEE) events carries crucial information on the origin/acceleration of energetic electrons at the Sun. Using  the Wind 3DP electron measurements at ~1 to 200 keV during 1995-2019, we select 11 good SEE events with a bump-like break in the peak flux vs. energy spectrum, different from the typical SEE events with a double-power-law spectrum. For the selected 11 events, the background-subtracted electron peak flux versus energy spectrum fits well to two functions: the sum of a single-power-law and a Gaussian function (spectral function #1) and the product of a single-power-law and the natural exponential form of a Gaussian function (spectral function #2). For the spectral function #1 (#2), on average, the fitted spectral index is 2.6±0.4 (2.7±0.6), significantly larger than the low-energy power-law index of typical SEE events, while the fitted center energy of spectral bump is 24±7 keV (75±38 keV) and the ratio of bump width and center is 2.0±0.7 (3.4±2.8). Among these 11 events, respectively, ~78%, ~89%, ~90%, 100% and ~55% are associated with GOES SXR flares, RHESSI HXR flares, west-limb CMEs, type III radio bursts and type II  radio bursts. Thus, these bump events have a stronger association with flares, coronal mass ejections (CMEs) and type II radio bursts, compared to the typical SEE events. In addition, we find a positive correlation between the center energy of bump and the CME speed. Therefore, we come up with an acceleration picture of these bump SEE events: the power-law portion is probably accelerated by flares with the acceleration efficiency larger at lower energies, while the bump portion is likely accelerated in CME-related processes with the acceleration efficiency increasing with the CME speed.

How to cite: Li, W., Wang, L., and Wang, W.: Solar Energetic Electron Events with a Spectral Bump, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11362, https://doi.org/10.5194/egusphere-egu23-11362, 2023.

EGU23-12330 | ECS | Orals | ST1.10 | Highlight

When are energetic electrons producing NO directly in the upper stratosphere? 

Josephine Salice, Hilde Nesse, Noora Partamies, Emilia Kilpua, Andrew Kavanagh, Eldho Babu, and Christine Smith-Johnsen

Compositional NOx changes caused by energetic electron precipitation (EEP) at a specific altitude are called the EEP direct effect. Changes co-dependent on vertical transport are referred to as the EEP indirect effect. The relative importance of EEP’s direct and indirect effect on NO and its subsequent impact on ozone and dynamic changes remain unresolved. The challenges are partly due to inadequate particle measurement and the relative scarcity of NO observations over the polar MLT region. Moreover, lower production rates in the mesosphere make it challenging to determine EEP’s direct impact on NO since small in-situ enhancements cannot be easily distinguished from the descending NO-rich air masses in the winter hemisphere. In this study, the uncertainty of the EEP observations is bypassed by exclusively identifying events applying NO-observations from the SOFIE instrument on board the AIM satellite. SOFIE daily averaged data from 2007 to 2014 is used to create a climatology based on the mean of the lower half of the data (lower 50 percentile mean). A direct EEP-produced NO-event at 90 km (“90km-event”) is identified when the NO density surpasses the climatology by 100%. If the NO density exceeds 25% above the climatology at 80, 70, 60, and 50 km, the event qualifies as a “50km-event”. By contrasting the 90km and 50km events, the characteristics of the solar wind and geomagnetic indices, as well as observed electron fluxes from POES, are studied. The goal is to unravel when EEP can produce NO directly in the upper stratosphere. The result will contribute to developing a parameterization of EEP from the radiation belt that includes both the direct and indirect impact of EEP to decipher the total EEP effect on the ozone and atmospheric dynamics.

How to cite: Salice, J., Nesse, H., Partamies, N., Kilpua, E., Kavanagh, A., Babu, E., and Smith-Johnsen, C.: When are energetic electrons producing NO directly in the upper stratosphere?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12330, https://doi.org/10.5194/egusphere-egu23-12330, 2023.

EGU23-13801 | ECS | Posters virtual | ST1.10

Witnessing a Forbush Decrease with a Microscintillator Ionisation Detector over the Atlantic Ocean 

Justin Tabbett, Karen Aplin, and Susana Barbosa

A novel ionisation detector, previously deployed on meteorological radiosonde flights, has demonstrated responsivity to X-rays and gamma radiation, and additionally, is thought to be sensitive to ionising radiation from cosmic rays. The PiN detector, composed of a 1x1x0.8 cm3 CsI(Tl) microscintillator coupled to a PiN photodiode, was deployed on the NRP Sagres sailing vessel on a cruise in the Atlantic between Portugal and the Azores in 2021. The instrument can determine both the count rate and energy of incoming ionising radiation particles.

The instrument was operational during the voyage in November 2021 when a coronal mass ejection event induced a sudden decrease in the observed cosmic ray intensity, known as a Forbush decrease. We present data recorded by the ionisation detector during this period, to characterise the instrument’s ability to detect cosmic ray events, and we compare the performance with neutron monitoring stations Oulu in Finland, and Dourbes in Belgium. As the PiN detector provides spectral and count rate data, it is possible to group events by their energy, and investigate the count rates of specific energy regimes. This approach is useful as many sources – including high and low energy ionising radiation from cosmic rays – contribute to the background energy spectrum. As a result, more meaningful comparisons and relationships can be established with the neutron monitoring stations.

How to cite: Tabbett, J., Aplin, K., and Barbosa, S.: Witnessing a Forbush Decrease with a Microscintillator Ionisation Detector over the Atlantic Ocean, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13801, https://doi.org/10.5194/egusphere-egu23-13801, 2023.

EGU23-14711 | Orals | ST1.10

Monitoring of Solar Energetic Particles and Cosmic Rays with the RADEM instrument onboard the ESA JUICE mission 

Wojtek Hajdas, Patricia Goncalves, Marco Pinto, Andre Galli, and Olivier Witasse

The main goal of the radiation monitor RADEM flying onboard the ESA JUICE mission is to provide continuous information on particle fluxes and their energy spectra. The monitor measures electrons up to 40 MeV and protons up to 250 MeV. Such a range of energies detected by RADEM enables covering the most hazardous regimes in terms of radiation damage. Spectroscopic information on particle energies is provided using eight quasi-logarithmic energy bins. RADEM has also a dedicated heavy-ion detector designed to measure a variety of heavy ion species with their LET between 0.1 and 10 MeV/cm/mg-1. Moreover, the monitor contains an additional detector sensitive to the direction of incoming radiation. It expands the instrument's angular coverage up to 35% of the sky. Apart from its spectroscopic and angular distribution functions, RADEM will continuously provide values of the radiation dose deposited by each particle species. Its telemetry data will be stored in the data center for the JUICE mission operated by the European Space Astronomy Centre. After preprocessing the higher-level data will become available to the JUICE scientific team. RADEM will be switched on shortly after the JUICE launch planned for April 2023 and after a short commissioning phase will start its nominal operation. Apart from regular and short tuning and calibration periods, it will remain operating for the rest of the mission i.e. almost 10 years. While its primary purpose is to monitor the mission levels for safety concerns of the spacecraft and its scientific payload, its measurements open a unique opportunity for conducting real-time, continuous observations during its full cruise to Jupiter. RADEM will study all aspects of the radiation phenomena characteristic to the Earth and Solar System. Correlations with other instruments will allow for advanced observations of particle event propagation and a better understanding of processes related to the dynamics of particle environments including their links with solar activity and magnetic fields across the solar system. In particular, during its first two years of the cruise to Jupiter, RADEM will precisely map the radiation environment between Venus and Mars, providing uninterrupted time-resolved spectroscopy and dosimetry data from Solar Energetic Particles and Cosmic Rays.

How to cite: Hajdas, W., Goncalves, P., Pinto, M., Galli, A., and Witasse, O.: Monitoring of Solar Energetic Particles and Cosmic Rays with the RADEM instrument onboard the ESA JUICE mission, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14711, https://doi.org/10.5194/egusphere-egu23-14711, 2023.

EGU23-15517 | Posters on site | ST1.10

Proton energy spectra of energetic storm particle events and their relation with magnetic turbulence and intermittency nearby interplanetary shocks 

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

Shock waves propagating in the interplanetary space are efficient sources of energetic particles. In situ spacecraft observations, especially particle fluxes which can be used to obtain energy spectra, provide very useful data for the investigation of the acceleration mechanisms occurring at shocks. In this work we analyse the kinetic energy spectra of several proton flux enhancements associated with energetic storm particle (ESP) events observed by various spacecraft. ESP events occurring both in association with and in absence of Solar Energetic Particles (SEPs) are considered. Moreover, ESP events associated both with quasi-perpendicular and quasi parallel shocks are investigated.  Different functional forms (i.e. Weibull function, double power law, and Ellison-Ramaty) are used to fit the observed spectra and the obtained results are discussed in relation to the shock properties and to the magnetic turbulence and intermittency in the upstream and downstream regions. More specifically, the properties of magnetic turbulence and intermittency are analysed by calculating power spectral densities and structure functions of the fluctuations of the magnetic field components and the implications for particle acceleration are examined.

This research has been carried out in the framework of the CAESAR 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 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 their relation with magnetic turbulence and intermittency nearby interplanetary shocks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15517, https://doi.org/10.5194/egusphere-egu23-15517, 2023.

EGU23-15621 | ECS | Posters on site | ST1.10

The effect of magnetic reconnection on ICME-related GCR modulation 

Emma Davies, Camilla Scolini, Réka Winslow, and Andrew Jordan

The large-scale magnetic structure of interplanetary coronal mass ejections (ICMEs) has been shown to cause temporary decreases in the galactic cosmic ray (GCR) flux measured in situ by spacecraft, known as Forbush decreases (Fds). In some ICMEs, the magnetic ejecta exhibits a magnetic flux rope structure; the strong magnetic field strength and closed field line geometry of such ICME magnetic flux ropes has been proposed to act as a shield to GCR transport. However, as ICMEs propagate, they undergo many processes including interactions and magnetic reconnection with the interplanetary magnetic field (IMF) in large-scale solar wind structures and other solar transients. In this study, we investigate how ICME interaction and reconnection during propagation affects Fd size, shape, and duration. We hypothesize that the alteration of the ICME magnetic topology due to reconnection (specifically the opening of the closed magnetic field configuration in the ICME flux rope) will have a strong effect on the ICME’s ability to modulate GCRs. To test this hypothesis, we compare the Fds of ICMEs that likely underwent reconnection during propagation with ones that likely did not.

To this end, we identify ICMEs that exhibited open magnetic field line topologies (i.e., ones that likely underwent reconnection) and we compare their effects on GCRs with those of ICMEs that exhibited closed topologies (both ends connected to the Sun). We use magnetic field, solar wind plasma, and suprathermal electron pitch angle distribution data at ACE and Wind to select the ICMEs. Furthermore, we use data by the SOPO and McMurdo neutron monitors at Earth to investigate how the magnetic structure of the ICME ejecta modulates the GCRs by comparing the resulting Fds for the selected ICMEs. The results of our study yield new insights into how the modulation of GCRs is affected by ICME evolution and interaction during propagation and whether reconnection of the ICME flux rope weakens its modulation of GCRs.

How to cite: Davies, E., Scolini, C., Winslow, R., and Jordan, A.: The effect of magnetic reconnection on ICME-related GCR modulation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15621, https://doi.org/10.5194/egusphere-egu23-15621, 2023.

EGU23-16136 | Posters on site | ST1.10

Energetic Electron Precipitation during Slot Region Filling Events 

Hilde Nesse, Eldho Midhun Babu, Josephine Salice, and Bernd Funke

The region separating the inner and outer radiation belt, typically devoid of energetic electrons, is termed the slot region. The outer edge of the slot region marks the equatorward edge of the energetic electron precipitation (EEP) originating from the outer radiation belt. Its varying location is strongly linked to the plasmasphere and geomagnetic activity. As such, geomagnetic indices are used to estimate the equatorward extent of the EEP region. There are, however, numerous reports where the energetic electrons cross these boundaries and fill the slot region, during which energetic electrons that can precipitate into the atmosphere long after the geomagnetic activity subsides. This is a missing source of energy input in current EEP estimates based on geomagnetic indices.

This study explores the occurrence rate, reformation, local time dependence, and energy deposition of slot region filling events. Medium energy electron measurements from the NOAA/POES over a full solar cycle from 2004 to 2014 are applied. We combine observations from the MEPED 0° and 90° detectors together with theory of pitch angle diffusion by wave-particle interaction to estimate the precipitating fluxes. To explore the energy dependent characteristics, each of the MEPED energy channels, > 43, >114, and >292 keV are evaluated independently. Finally, we investigate the potential EEP impact on the NO density utilizing seven years of Envisat MIPAS NO observations from 2005 to 2011.

How to cite: Nesse, H., Babu, E. M., Salice, J., and Funke, B.: Energetic Electron Precipitation during Slot Region Filling Events, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16136, https://doi.org/10.5194/egusphere-egu23-16136, 2023.

EGU23-16177 | Orals | ST1.10 | Highlight

Risks of space radiation exposure to exploration astronauts: limitations in predictions based on the ground experiments and possible solutions 

Salman Khaksarighiri, Robert Wimmer-Schweingruber, Jingnan Guo, Cary Zeitlin, Thomas Berger, and Daniel Matthiä

Future expeditions into interplanetary space, and in particular to the Moon and Mars, will expose astronauts to very high levels of cosmic radiation, which are known due to years of research and instruments that have been sent to space. It is, however, a limitation in understanding the risks of this radiation for the human body due to difficulties in simulating the complex space environment on Earth or complex human phantom and the inability to extrapolate human clinical outcomes based on animal models or simulation results. 
As human spaceflight continues on its path to success, we need to develop appropriate and effective mitigation strategies for future missions to improve our understanding of the space radiation risk by identifying the constraints of radiation research on the Earth and finding possible solutions based on the existing technologies to be closer to the reality as much as possible and better understand human physiology in space.  
As part of this paper, we have identified several factors that hinder our understanding of radiation risks for human crews and have identified ways to cope with these restrictions for a better understanding and preparation for human spaceflights in the future.

How to cite: Khaksarighiri, S., Wimmer-Schweingruber, R., Guo, J., Zeitlin, C., Berger, T., and Matthiä, D.: Risks of space radiation exposure to exploration astronauts: limitations in predictions based on the ground experiments and possible solutions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16177, https://doi.org/10.5194/egusphere-egu23-16177, 2023.

EGU23-3207 | ECS | Posters on site | ST1.11

The change of properties of solar wind turbulence across different types of interplanetary shocks 

Byeongseon Park, Alexander Pitňa, Jana Šafránková, Zdeněk Němeček, Oksana Krupařová, and Vratislav Krupař

The interaction between interplanetary (IP) shocks and solar wind has been studied for the understanding of energy dissipation mechanisms and the properties of turbulence (e.g., cross helicity, residual energy, proton temperature anisotropy, magnetic compressibility, etc.) within collisionless plasmas. Compared to the study of the interaction with fast shocks, less attention has been directed to the interaction with other types of IP shocks including slow mode shocks (i.e., fast forward, fast reverse, slow forward and slow reverse). We analyze IP shocks observed by the Wind spacecraft from 1995 to 2021. Spectral indices in the ion inertial and kinetic ranges for the upstream and downstream magnetic field fluctuations are estimated by continuous wavelet transform. The changes of the plasma turbulence properties and the distributions of characteristic proton length scales are presented. We preliminarily found that spectral indices in both inertial and kinetic ranges and the distributions of characteristic proton length scales are statistically conserved across the investigated shocks. Mechanisms associated with the energy dissipation can be seen unaffected by shock. Other turbulence properties—cross helicity, residual energy and proton temperature anisotropy—evolve without a significant modification as well.

How to cite: Park, B., Pitňa, A., Šafránková, J., Němeček, Z., Krupařová, O., and Krupař, V.: The change of properties of solar wind turbulence across different types of interplanetary shocks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3207, https://doi.org/10.5194/egusphere-egu23-3207, 2023.

EGU23-3214 | Posters on site | ST1.11

Evolution of magnetic field fluctuations and their spectral properties within the heliosphere: Statistical approach 

Jana Safrankova, Zdeněk Němeček, František Němec, Daniel Verscharen, Lubomír Přech, Timothy S. Horbury, and Stuart D. Bale

The contribution presents the first comprehensive statistical study of the evolution of both compressive and non-compressive magnetic field fluctuations in the inner heliosphere. Based on Parker Solar Probe and Solar Orbiter data in various distances from the Sun, we address the general trends and compare them with Wind observations near 1 AU. We analyze solar wind power spectra of magnetic field fluctuations in the inertial and kinetic ranges of frequencies. We found a systematic steepening of the spectrum in the inertial range with the spectral index of around –3/2 at closest approach to the Sun toward –5/3 at larger distances (above 0.4 AU), the spectrum of the magnetic field component perpendicular to the background field being steeper at all distances. In the kinetic range, spectral indices increase from –4.5 at closest PSP approach to –3 at ≈0.4 AU and this value remains constant toward 1 AU. We show that the radial profiles of spectral slopes, fluctuation amplitudes, spectral breaks and their mutual relation rapidly change near 0.4 AU.

How to cite: Safrankova, J., Němeček, Z., Němec, F., Verscharen, D., Přech, L., Horbury, T. S., and Bale, S. D.: Evolution of magnetic field fluctuations and their spectral properties within the heliosphere: Statistical approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3214, https://doi.org/10.5194/egusphere-egu23-3214, 2023.

EGU23-6538 | Posters on site | ST1.11

A detailed analysis of ion-acoustic waves observed in the solar wind by the Solar Orbiter 

David Pisa, Jan Soucek, Ondrej Santolik, Tomas Formanek, Milan Maksimovic, Thomas Chust, Yuri Khotyaintsev, Matthieu Kretzschmar, Christopher Owen, Philippe Louarn, and Andrei Fedorov

Ion-acoustic waves are often observed in the solar wind along the Solar Orbiter’s orbit. These electrostatic waves are generated via ion-ion or current-driven instabilities below the local proton plasma frequency. Due to the Doppler shift, they are typically observed in the frequency range between the local electron and proton plasma frequency in the spacecraft frame. Ion-acoustic waves often accompany large-scale solar wind structures and play a role in the energy dissipation in the propagating solar wind. Time Domain Sampler (TDS) receiver, a part of the Radio and Plasma Waves (RPW) instrument, is sampling wave emissions at frequencies below 200 kHz almost continuously from the beginning of the mission. Almost three years of observations allow us to perform a detailed study of ion-acoustic waves in the solar wind under variable plasma conditions. The emission tends to be observed when proton density and temperature are highly perturbed. A detailed analysis of the proton velocity distribution and wave generation using solar wind data from a Proton and Alpha particle Sensor (PAS) of the Solar Wind Analyzer (SWA) is shown.

How to cite: Pisa, D., Soucek, J., Santolik, O., Formanek, T., Maksimovic, M., Chust, T., Khotyaintsev, Y., Kretzschmar, M., Owen, C., Louarn, P., and Fedorov, A.: A detailed analysis of ion-acoustic waves observed in the solar wind by the Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6538, https://doi.org/10.5194/egusphere-egu23-6538, 2023.

EGU23-6669 | Posters on site | ST1.11

Wave turbulence in inertial electron magnetohydrodynamics 

Vincent David and Sébastien Galtier

A wave turbulence theory is developed for inertial electron magnetohydrodynamics (IEMHD) in the presence of a relatively strong and uniform external magnetic field B0 = B0e. This regime is relevant for scales smaller than the electron inertial length de. We derive the kinetic equations that describe the three-wave interactions between inertial whistler or kinetic Alfvén waves. We show that for both invariants, energy and momentum, the transfer is anisotropic (axisymmetric) with a direct cascade mainly in the direction perpendicular (⊥) to B0. The exact stationary solutions (Kolmogorov–Zakharov spectra) are obtained for which we prove the locality. We also found the Kolmogorov constant CK ≃ 8.474. In the simplest case, the study reveals an energy spectrum in k−5/2k−1/2 (with k the wavenumber) and a momentum spectrum enslaved to the energy dynamics in k−3/2k−1/2. These solutions correspond to a magnetic energy spectrum ∼k−9/2, which is steeper than the EMHD prediction made for scales larger than de.

How to cite: David, V. and Galtier, S.: Wave turbulence in inertial electron magnetohydrodynamics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6669, https://doi.org/10.5194/egusphere-egu23-6669, 2023.

Turbulent plasmas such as the solar wind and the magnetosheath exhibit an energy cascade which is present across a broad range of scales, from the stirring scale at which energy is injected, down to the smallest scales where energy is dissipated through processes such as reconnection and wave-particle interactions. Recent observations of Earth’s bow shock reveal the presence of a disordered or turbulent transition region which exhibits some features of turbulent dissipation, such as reconnecting current sheets. Understanding the variations in the origin and character of these disordered fluctuations addresses open questions such as how disordered or turbulent fluctuations in the bow shock and magnetosheath are related, and how quickly magnetosheath turbulence arises from bow shock processes. Here, we present two case studies of bow shock crossings observed by Magnetospheric Multiscale (MMS), one quasi-perpendicular and one quasi-parallel. Using high-cadence, combined search-coil and fluxgate magnetometer data, we measure changes in correlation lengths of the magnetic field through three regions: the upstream (solar wind), shock transition region, and downstream (magnetosheath). The influence of the discontinuous shock ramp is reduced using high-pass filters with variable cut-off frequencies. We find that correlation lengths are higher on the solar wind side of the shock, reducing to around 20 ion inertial lengths in the magnetosheath for both the quasi-parallel and the quasi-perpendicular shocks. We also discuss implications of the observed evolution of the correlation length to bow shock and magnetosheath processes.

How to cite: Plank, J. and Gingell, I.: Measures of correlation length at Earth’s quasi-parallel and quasi-perpendicular bow shock, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6971, https://doi.org/10.5194/egusphere-egu23-6971, 2023.

EGU23-7895 | Posters on site | ST1.11

The ‘Inverse-Gaussian’ SW proton populations: Do they tell something about heating/acceleration by turbulence ? 

Philippe Louarn and the SWA Team + RPW and MAG

The solar wind proton distributions measured by PAS (Proton Alfa Sensor -Solar Orbiter)  are often constituted by a core and a beam. If the core is generally gaussian, the beam is asymmetric and non-gaussian with a more populated high-energy side (‘heavy tail’) in the magnetic field direction. It appears that the ‘Inverse Gaussian Distribution’ (IG), a type of hyperbolic statistical distributions, provides good fits of these skewed distributions. Then, excellent models of the whole proton distribution are obtained by superposing a gaussian (or almost gaussian distribution) for the core and an IG for the beam.  This modelling (Gaussian + Inverse Gaussian) applies to different situations: relatively slow and fast winds, single and double-bump populations, low or high level of turbulence. An interpretation is given, inspired by the ‘Normal-Inverse Gaussian’ (NIG) process, common in finance applications. Our ‘toy’ model assumes that the acceleration/heating is modelled as a drifting gaussian process in velocity space controlled (or subordinated) by an independent time-control process that follows an IG distribution. It is proposed that this control process is linked to the time of residence of the particles within accelerating structures of finite size, the relative motion between the particles and the structures being a drifting random walk (problem of the 'first passage time' of a random walk). Some applications of the model are discussed, as the estimate of the relative importance of heating and acceleration or the possible role of ambipolar fields.

How to cite: Louarn, P. and the SWA Team + RPW and MAG: The ‘Inverse-Gaussian’ SW proton populations: Do they tell something about heating/acceleration by turbulence ?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7895, https://doi.org/10.5194/egusphere-egu23-7895, 2023.

EGU23-7919 | Posters virtual | ST1.11

Mechanical and Total Pressure Statistics in Vlasov-Maxwell Plasmas 

Subash Adhikari, Paul A. Cassak, Tulasi N. Parashar, William H. Matthaeus, and Michael A. Shay

Pressure is an important parameter in plasma turbulence. Historically, pressure fluctuations have been studied extensively via density in the nearly incompressible (NI) magnetohydrodynamic (MHD) framework1-3. However, the statistics of mechanical and total pressure in kinetic plasmas have not been explored much. In this study, we examine the statistics of mechanical and total pressure using a 2.5D particle-in-cell (PIC) simulation of plasma turbulence4. As turbulence is fully developed in the system, it is found that the magnetic and thermal pressure display a negative correlation keeping the total pressure about constant, consistent with MHD behavior. This negative correlation is observed locally in regions near the current sheets and justified by the nature of the joint probability distribution of the two5. Further, pressure spectra are calculated for magnetic, thermal and total pressure. The thermal and magnetic pressure spectra exhibit a slope of -5/3 in the inertial range, while the total pressure spectrum exhibits a slope of -7/3 in agreement with hydrodynamic scaling, influenced by the cross-spectral contribution of the individual pressures. Finally, the implications of the local structures of pressure to intermittency are discussed using probability distribution functions and scale dependent kurtosis.

1. Montgomery, D., Brown M. R., and Matthaeus W. H. "Density fluctuation spectra in magnetohydrodynamic turbulence"JGR: Space Physics A1 (1987): 282-284.

2. Matthaeus, W. H., Brown M. R., "Nearly incompressible magnetohydrodynamics at low Mach number"The Physics of Fluids 12 (1988): 3634-3644.

3. Matthaeus, W. H., et al. "Nearly incompressible magnetohydrodynamics, pseudosound, and solar wind fluctuations" JGR: Space Physics A4 (1991): 5421-5435.

4. Adhikari, S., et al. "Energy transfer in reconnection and turbulence" Physical Review E 6 (2021): 065206.

5. Adhikari S., et al. “Statistics of Total Pressure in Kinetic Plasma Turbulence" ESS Open Archive (2023).

How to cite: Adhikari, S., Cassak, P. A., Parashar, T. N., Matthaeus, W. H., and Shay, M. A.: Mechanical and Total Pressure Statistics in Vlasov-Maxwell Plasmas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7919, https://doi.org/10.5194/egusphere-egu23-7919, 2023.

EGU23-8164 | Posters on site | ST1.11

The location of the spectral break in compressible fluctuations in the solar wind. 

Owen Roberts, Rumi Nakamura, Yasuhito Narita, and Zoltan Voros

We use density deduced from spacecraft potential to study the power spectral density (PSD) of fluctuations in the solar wind. Typically plasma measurements do not have high enough time resolutions to resolve ion kinetic scales. However, calibrated spacecraft potential allows much higher time resolutions to resolve the spectral break between ion inertial and kinetic ranges. Fast Survey mode data from Magnetospheric MultiScale data are used when the spacecraft were in the pristine solar wind. We find that the density spectra' morphology differs from the magnetic field fluctuations, with a flattening often occurring between inertial and kinetic ranges. We find that the spectral break of the trace magnetic field fluctuations occurs near the expected frequency for cyclotron resonance or magnetic reconnection. Meanwhile, the spectral break at the start of the ion kinetic range for density fluctuations is often at a higher frequency when compared to the magnetic field. We discuss possible interpretations for these observations. Two plausible scenarios are presented; 1. the compressive fluctuations consist of a slow wave cascade at large scales before kinetic Alfven waves become dominant at smaller scales 2. charge separation begins to occur at these scales, and the Hall electric field starts to play a role. 

How to cite: Roberts, O., Nakamura, R., Narita, Y., and Voros, Z.: The location of the spectral break in compressible fluctuations in the solar wind., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8164, https://doi.org/10.5194/egusphere-egu23-8164, 2023.

EGU23-8601 | ECS | Orals | ST1.11

Whistler wave occurrence in the magnetosheath: comparing the quasi-parallel and quasi-perpendicular geometries 

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

​​The Earth’s magnetosheath is a turbulent plasma region where the interplay between coherent structures and various plasma waves affect the particle dynamics and energy transfer. The properties of the magnetosheath are controlled by the upstream conditions. Magnetosheath plasma downstream of a quasi-parallel bow shock (the angle between the shock normal and the interplanetary magnetic field being less than 45°) tends to have stronger fluctuations while a quasi-perpendicular shock leads to a more stationary magnetosheath. These two geometries create different environments for processes such as wave generation. One example is whistler waves that can be excited by non-Maxwellian electron velocity distributions formed in local magnetic structures. Whistler waves have been observed throughout the magnetosheath. As previous statistical studies have considered the region as a whole, it is yet unexplored which magnetosheath geometry creates more favorable conditions for whistler wave generation.

In this work, we address this issue and investigate how the occurrence and properties of whistler waves depend on the magnetosheath configuration. We detect whistler waves using data from the Magnetospheric Multiscale (MMS) mission. We compare whistler wave occurrence to the shock normal angle estimated from upstream conditions, as well as local conditions which are typically different between the quasi-parallel and quasi-perpendicular geometries. The results give an indication of the conditions needed for the whistler waves to efficiently dissipate energy in the turbulent magnetosheath.

How to cite: Svenningsson, I., Yordanova, E., Khotyaintsev, Y. V., André, M., and Cozzani, G.: Whistler wave occurrence in the magnetosheath: comparing the quasi-parallel and quasi-perpendicular geometries, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8601, https://doi.org/10.5194/egusphere-egu23-8601, 2023.

The magnetometer onboard the NOAA DSCOVR spacecraft samples the interplanetary magnetic field at 50 samples/second, presenting unique opportunities to study turbulence and plasma waves in the solar wind up to the instruments 25 Hz Nyquist. In this study, we present example observations by DSCOVR of turbulence and Alfven waves during periods of solar flares, coronal mass ejections, and solar energetic particle (SEP)events. We present the turbulence structures, including spectral indices at different frequencies, and discuss how it relates to coherence waves observed during cascade and dissipation. We also present wave properties, including frequency range, wave power and polarization. In addition, by comparing DSCOVR to ACE and Wind results, we discuss the dependency of solar wind parameters on spacecraft separation and the implications for studying the evolution of cascading turbulence. Finally, we explain how users can access this distinctive DSCOVR full high-resolution magnetic field dataset through the NOAA-NCEI DSCOVR portal.

How to cite: Loto'aniu, P.: DSCOVR Turbulence and Plasma Wave Observations at L1, and Correlation of Solar Wind Parameters With Spacecraft Separation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8757, https://doi.org/10.5194/egusphere-egu23-8757, 2023.

EGU23-8810 | Orals | ST1.11

Transmission of turbulent structures and energetic particles dynamics in the interaction between collisionless shocks and plasma turbulence. 

Domenico Trotta, Francesco Pecora, Adriana Settino, Denise Perrone, David Burgess, David Lario, Heli Hietala, Timothy Horbury, Rami Vainio, Luis Preisser, William Matthaeus, Oreste Pezzi, Sergio Servidio, and Francesco Valentini

The interaction between shock and turbulence is an important pathway to energy conversion and particle acceleration in a large variety of astrophysical systems. Novel insights of such an interaction will be presented.

Using a combination of in-situ observations (using the Wind spacecraft and Magnetospheric Multiscale mission, MMS) and self-consistent kinetic simulations, the transmission of turbulent structures across the Earth’s bow shock will be discussed first. Then, the role of turbulence strength for efficient particle diffusion in phase space will be discussed using novel kinetic simulations and will be put in the context of observations of very-long lasting field aligned beams in interplanetary space. Finally, novel three-dimensional simulations of the shock turbulence interplay will be presented, with a focus on the shock front behaviour and irregular proton heating in presence of pre-existing fluctuations. In this scenario, the importance of novel multi-spacecraft missions will be discussed.

How to cite: Trotta, D., Pecora, F., Settino, A., Perrone, D., Burgess, D., Lario, D., Hietala, H., Horbury, T., Vainio, R., Preisser, L., Matthaeus, W., Pezzi, O., Servidio, S., and Valentini, F.: Transmission of turbulent structures and energetic particles dynamics in the interaction between collisionless shocks and plasma turbulence., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8810, https://doi.org/10.5194/egusphere-egu23-8810, 2023.

EGU23-8814 | Posters virtual | ST1.11

Comparative MMS analysis of Markov turbulence in the magnetosheath on kinetic scales 

Wiesław M. Macek and Dariusz Wójcik

We apply Fokker-Planck equation to investigate processes responsible for turbulence in space plasma. In our previous studies, we have shown that turbulence in the inertial range of hydromagnetic scales exhibits Markov properties [1,2]. We have also extended this statistical approach on much smaller scales, where kinetic theory should be applied. Namely, we have already obtained the results of the statistical analysis of magnetic field fluctuations in the Earth’s magnetosheath based on the Magnetospheric Multiscale (MMS) mission [3]. Here we compare the characteristics of turbulence behind the bow shock, inside the magnetosheath, and near the magnetopause. We check whether the second order approximation of the Fokker-Planck equation leads to kappa distribution of the probability density function provided that the first Kramers-Moyal coefficient is linear and the second term is quadratic, describing drift and diffusion correspondingly, which is a generalization of Ornstein-Uhlenbeck process. In some cases the power-law distributions are recovered. For moderate scales we have the kappa distributions described by various peaked shapes with heavy tails. In particular, for large values of the kappa parameter this is reduced to the normal Maxellian distribution. The obtained results on kinetic scales could be important for a better understanding of the physical mechanism governing turbulent systems in laboratory and space.

Keywords: Kinetic scales, Markov processes, MMS probe, Plasmas, Solar wind, Turbulence.

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

References

1. Strumik, M., & Macek, W. M. 2008a, Testing for Markovian character and modeling of intermittency in solar wind turbulence, Physical Review E, 78, 026414, doi=10.1103/PhysRevE.78.026414.
2. Strumik, M., & Macek, W. M. 2008b, Statistical analysis of transfer of fluctuations in solar wind turbulence, Nonlinear Processes in Geophysics, 15, 607-613, doi=10.5194/npg-15-607-2008.
3. Macek, W. M., Wójcik, D. & Burch, J. L. 2023, Magnetospheric Multiscale observations of Markov turbulence on kinetic scales, arXiv=2211.05098, Astrophysical Journal, https://doi.org/10.3847/1538-4357/aca0a0.

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How to cite: Macek, W. M. and Wójcik, D.: Comparative MMS analysis of Markov turbulence in the magnetosheath on kinetic scales, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8814, https://doi.org/10.5194/egusphere-egu23-8814, 2023.

EGU23-8938 | Orals | ST1.11

Theoretical Developments on Energy Conversion via the Pressure-Strain Interaction 

Paul Cassak and M. Hasan Barbhuiya

Energy conversion between bulk kinetic and thermal energy in weakly collisional and collisionless plasma processes such as magnetic reconnection and plasma turbulence has recently been the subject of intense scrutiny. This channel of energy conversion is described by the pressure-strain interaction. In a closed system, this quantity accounts for all the net change of the thermal energy. It is common to decompose it into pressure dilatation and «Pi-D», which isolates energy conversion via compressible and incompressible physics, respectively. Here, we propose an alternative decomposition of pressure-strain interaction that instead isolates flow convergence/divergence and bulk flow shear. We furnish a simple example to illustrate how Pi-D can be counterintuitive and the new decomposition is intuitive. Moreover, for applications to magnetized plasmas, we derive the pressure-strain interaction in a magnetic field-aligned coordinate system. This results in its decomposition into eight terms, each with a different physical mechanism that changes the thermal energy. Results from particle-in-cell simulations of two-dimensional magnetic reconnection plotting the decompositions in both Cartesian and magnetic field-aligned coordinates are shown. We identify the mechanisms contributing to heating and cooling during reconnection. The results of this study are readily applicable for interpreting numerical and observational data of pressure-strain interaction in both Cartesian and field-aligned coordinates in fundamental plasma processes such as reconnection, turbulence and collisionless shocks.

How to cite: Cassak, P. and Barbhuiya, M. H.: Theoretical Developments on Energy Conversion via the Pressure-Strain Interaction, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8938, https://doi.org/10.5194/egusphere-egu23-8938, 2023.

EGU23-9803 | ECS | Posters on site | ST1.11

Measurement of the rate of change of the electron heat flux due to the whistler instability with Solar Orbiter observations 

Jesse Coburn, Daniel Verscharen, Christopher Owen, Timothy Horbury, Milan Maksimovic, Christopher Chen, Fan Guo, and Xiangrong Fu

Non-Maxwellian features of the coronal electron population are important for some models of solar wind acceleration processes. Remnants of these features are detectable in spacecraft observations, in particular in the form of field-aligned beams (strahl) and anti-sunward deficits in the electron distribution function. These features are shaped by expansion, collisions, and kinetic effects. Therefore, determining how these processes alter the distribution is important for our understanding of how the solar wind accelerates and evolves. The strahl and deficit contribute to the overall electron heat flux. If the heat flux crosses the threshold for instabilities, the plasma will generate waves which in turn reduce the heat flux via pitch-angle scattering of electrons out of the strahl and/or into the deficit. The work presented here examines an interval observed by Solar Orbiter during which short bandwidth whistler waves are observed by the Radio and Plasma Waves instrument. We apply a method to measure the pitch-angle gradient to high cadence pitch angle distribution (PAD) functions measured by the Electrostatic Analyser System to quantify the rate of change of heat flux from quasilinear theory. The primary part of the measurement technique is based on low-pass filtering of the PAD function with a Hermite-Laguerre transform providing a measurement of the pitch-angle gradient. We compare our quantification of the rate of change of the heat flux with other timescales and processes relevant in the solar wind. We show the potential of our technique to further our understanding of the role of wave-particle interactions in the evolution of the solar wind electrons.

How to cite: Coburn, J., Verscharen, D., Owen, C., Horbury, T., Maksimovic, M., Chen, C., Guo, F., and Fu, X.: Measurement of the rate of change of the electron heat flux due to the whistler instability with Solar Orbiter observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9803, https://doi.org/10.5194/egusphere-egu23-9803, 2023.

EGU23-11491 | Posters on site | ST1.11

On the Nature of Ion-to-Electron Scale Field Fluctuations in the Solar Wind: Insight from Artemis Observations, Simulations and Linear Theory 

Chadi Salem, John Bonnell, Christopher Chaston, Kristopher Klein, Luca Franci, and Vadim Roytershteyn

Recent observational and theoretical work on solar wind turbulence and dissipation suggests that kinetic-scale fluctuations are both heating and isotropizing the solar wind during transit to 1 AU.  The nature of these fluctuations and associated heating processes are poorly understood. Whatever the dissipative process that links the fields and particles - Landau damping, cyclotron damping, stochastic heating, or energization through coherent structures - heating and acceleration of ions and electrons occurs because of electric field fluctuations. The dissipation due to the fluctuations depends intimately upon the temporal and spatial variations of those fluctuations in the plasma frame.  In order to derive that distribution in the plasma frame, one must also use magnetic field and density fluctuations, in addition to electric field fluctuations, as measured in the spacecraft frame (s/c) to help constrain the type of fluctuation and dissipation mechanisms that are at play.

We present here an analysis of electromagnetic fluctuations in the solar wind from MHD scales down to electron scales based on data from the Artemis spacecraft at 1 AU. We focus on a few time intervals of pristine solar wind, covering a reasonable range of solar wind properties (temperature ratios and anisotropies; plasma beta; and solar wind speed). We analyze magnetic, electric field, and density fluctuations from the 0.01 Hz (well in the inertial range) up to 1 kHz. We compute parameters such as the electric to magnetic field ratio, the magnetic compressibility, magnetic helicity, compressibility and other relevant quantities in order to diagnose the nature of the fluctuations at those scales between the ion and electron cyclotron frequencies, extracting information on the dominant modes composing the fluctuations. We also use the linear Vlasov-Maxwell solver PLUME to determine the various relevant modes of the plasma with parameters from the observed solar wind intervals. These results are supplemented by analysis of fully nonlinear kinetic simulations of decaying turbulence at small scales. We discuss the results and highlight  the relevant modes as well as the major differences between our results in the solar wind and results in the magnetosheath.

How to cite: Salem, C., Bonnell, J., Chaston, C., Klein, K., Franci, L., and Roytershteyn, V.: On the Nature of Ion-to-Electron Scale Field Fluctuations in the Solar Wind: Insight from Artemis Observations, Simulations and Linear Theory, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11491, https://doi.org/10.5194/egusphere-egu23-11491, 2023.

EGU23-12689 | ECS | Orals | ST1.11

Turbulence and whistlers in magnetic clouds observed by Solar Orbiter 

A. L. Elisabeth Werner, Emiliya Yordanova, Andrew P. Dimmock, and Ida Svenningsson

Kinetic processes control the cross-scale energy transfer between large-scale dynamics and dissipation in the solar wind. Large-scale magnetic flux ropes, also known as magnetic clouds (MCs), inside interplanetary coronal mass ejections (ICMEs) have been shown to effectively drive magnetospheric disturbances, but little is known about the turbulence properties and wave-particle interactions inside the MCs.

Here, we study the properties of the turbulence inside MCs between 0.3-1 AU observed by Solar Orbiter. We find that the spectral index in the inertial range fits Kolmogorov’s power law, but in the high-frequency regime we find a spectral bump at the beginning of a steeper power law regime. This is likely due to the presence of a significant number of whistler waves inside the MCs.

We have developed an automated search algorithm to find and record the properties of whistler waves inside MCs observed by Solar Orbiter. We find that MCs contain a significant number of whistler wave events with high magnetic field wave power (>0.5 nT2), which we do not find in the ICME sheath regions. We study these waves and attempt to determine their generation mechanism. In order to explore possible relations between the turbulence and the presence of whistler waves, we also determine the mean energy transfer rate, the magnetic field intermittency and the turbulent properties of the MCs and compare with the sheaths.  

How to cite: Werner, A. L. E., Yordanova, E., Dimmock, A. P., and Svenningsson, I.: Turbulence and whistlers in magnetic clouds observed by Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12689, https://doi.org/10.5194/egusphere-egu23-12689, 2023.

EGU23-13050 | ECS | Orals | ST1.11

Cross helicity modified by large-scale velocity shears in the solar wind 

Juska Soljento, Simon Good, Adnane Osmane, and Emilia Kilpua

Cross helicity quantifies the balance between counterpropagating Alfvénic fluctuations, which interact nonlinearly to generate turbulence in the solar wind. We have investigated how cross helicity is modified by large-scale velocity shears in the solar wind plasma. Using the linear Kelvin–Helmholtz (KH) instability threshold, we identified velocity shears at a 30-min timescale. The shears were associated with 74 interplanetary coronal mass ejection (ICME) sheaths observed by the Wind spacecraft at 1 au between 1997 and 2018. Typically weaker shears upstream of the sheaths and downstream in the ICME ejecta were also analyzed. Below the KH threshold, cross helicity was approximately invariant or weakly rising with shear amplitude. Above the KH threshold, fluctuations tended toward a balanced state with increasing shear amplitude. These findings are consistent with velocity shears being local sources of sunward fluctuations that act to reduce net imbalances in the antisunward direction, and suggest that the KH instability plays a role this process.

How to cite: Soljento, J., Good, S., Osmane, A., and Kilpua, E.: Cross helicity modified by large-scale velocity shears in the solar wind, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13050, https://doi.org/10.5194/egusphere-egu23-13050, 2023.

EGU23-13102 | ECS | Orals | ST1.11

Wavelet determination of scaling exponents and intermittency seen by Solar Orbiter 

Alina Bendt, Sandra Chapman, and Bogdan Hnat

The solar wind provides a natural laboratory for plasma turbulence at high Reynolds number. We use Solar Orbiter (SO) observations from the Magnetometer (MAG) and the Solar Wind Analyser Suite (SWA) to study extended intervals of homogeneous turbulence. Intervals which exhibit a clear scaling range of magnetohydrodynamic (MHD) turbulence, and transitions to both the ‘1/f’ range at low frequencies, and the kinetic range at frequencies where MHD is no longer valid, are selected. We ensure that all intervals are of steady solar wind flow and do not contain isolated structures such as shocks, pressure pulses and discontinuities.

Solar wind turbulence is anisotropic due to the presence of a background magnetic field. We first rotate the magnetic field into orthogonal coordinate systems with one coordinate parallel to the average direction of the magnetic field B0, a second coordinate perpendicular to both B0 and average solar wind flow direction U, and the third in the plane of both B0 and U. We then perform a Haar wavelet decomposition to obtain the timeseries of magnetic field fluctuations on multiple temporal scales. The Haar wavelet decomposition is by linearly spaced intervals in logarithmic frequency space and hence provides a precise determination of the power spectral exponents, discriminating between 5/3, 3/2 and other relevant values. It also directly estimates the Local Intermittency Measure, which characterizes localized coherent turbulent structures, and the structure functions, which quantify higher order scaling exponents.

We apply these methods to SO intervals in order to test for systematic dependencies on the properties of the turbulence with different plasma conditions and at different distances from the sun.

How to cite: Bendt, A., Chapman, S., and Hnat, B.: Wavelet determination of scaling exponents and intermittency seen by Solar Orbiter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13102, https://doi.org/10.5194/egusphere-egu23-13102, 2023.

EGU23-13543 | ECS | Orals | ST1.11

Quasi-Lagrangian studies of spatio-temporal correlation in incompressible MHD turbulence 

Raquel Mäusle and Wolf-Christian Müller

Turbulence is of fundamental importance for many physical systems on Earth and throughout the universe. A turbulent flow can be described as the superposition of turbulent fluctuations of various length scales, which interact with each other non-linearly, leading to a transfer of energy across scales. We aim at a better understanding of the temporal and spatial properties of this energy transfer process in plasma turbulence, by studying the spatio-temporal correlation between turbulent structures in magnetohydrodynamic (MHD) turbulence.

To this end we perform three-dimensional direct numerical simulations with a pseudo-spectral method. We employ the quasi-Lagrangian reference frame, in which tracer particles are followed in the flow each carrying with it a set of probes at fixed distances across which the fluctuations are computed. This avoids the large-scale sweeping effect, which in the case of fixed-grid (Eulerian) measurements would obscure the small-scale temporal dynamics. This approach is based on previous studies in Navier-Stokes turbulence [Physics of Fluids 23.8 (2011): 085107] and has been extended to account for the magnetic field.

We investigate systems with different mean magnetic field strength. The spatio-temporal correlation functions yield insight into the nature of the cross-scale transfer of energy in terms of the direction, strength, and time scale of the transfer process. In particular, the scaling of the correlation times perpendicular and parallel to the local magnetic field, the influence of the mean magnetic field and the implications for the current understanding of the cross-scale transfer process are discussed.

How to cite: Mäusle, R. and Müller, W.-C.: Quasi-Lagrangian studies of spatio-temporal correlation in incompressible MHD turbulence, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13543, https://doi.org/10.5194/egusphere-egu23-13543, 2023.

EGU23-13782 | ECS | Orals | ST1.11

Generalised Ohm’s Law in the Magnetosheath: How do plasma conditions impact turbulent electric fields? 

Harry Lewis, Julia Stawarz, Luca Franci, Lorenzo Matteini, Kristopher Klein, and Chadi Salem

Turbulence is a complex phenomenon whereby fluctuation energy is transferred between different scale sizes as a result of nonlinear interactions. Electromagnetic turbulence is ubiquitous within space plasmas, wherein it is associated with numerous nonlinear interactions. The dynamics of the magnetic field, which are widely studied in turbulence theory, are intimately linked to the electric field, which controls the exchange of energy between the magnetic field and the particles. Magnetospheric Multiscale (MMS) provides the unique opportunity to decompose electric field dynamics into contributions from different linear and nonlinear processes. The evolution of the electric field is described by generalised Ohm’s law, which breaks down the dynamics into components arising from different physical effects. Using high-resolution multipoint measurements, we compute the MHD, Hall and Electron Pressure terms of generalised Ohm’s law for 60 turbulent magnetosheath intervals. These terms, which have varying contributions to the dynamics as a function of scale, arise as a result of different physical effects related to a range of underlying turbulent phenomena. We examine how two characteristics of the turbulent electric field spectra depend on plasma conditions: the transition scale between MHD and Hall dominance (the ‘Hall scale’, kHall) and the relative amplitude of Hall and Electron Pressure contributions. Motivated by dimensional analysis arguments which appeal to characteristics of the plasma and the turbulence that can be quantified in a number of ways by MMS, we demonstrate the necessary refinements required to reproduce measured values. The scalar isotropic kinetic Alfven wave prediction for the ratio of Electron Pressure to Hall terms as a function of plasma beta is not consistent with measurements. We observe that the MHD and Hall terms are dominated by either nonlinear or linear dynamics, depending on the interval, while the Electron Pressure term is dominated by linear components only. Our work shows how contributions to turbulent dynamics change in different plasma conditions, which may provide insight into other turbulent plasma environments.  

How to cite: Lewis, H., Stawarz, J., Franci, L., Matteini, L., Klein, K., and Salem, C.: Generalised Ohm’s Law in the Magnetosheath: How do plasma conditions impact turbulent electric fields?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13782, https://doi.org/10.5194/egusphere-egu23-13782, 2023.

The solar wind plasma environment in the outer heliosphere is different from the inner heliosphere where has been widely studied. An important factor influencing the turbulence evolution in the outer heliosphere is the pickup ions, primarily originated from neutral atoms from the interstellar medium. Pickup ions are not readily assimilated by the background solar wind plasma and thus provide extra free energies which can drive ion-scale instabilities. The unstable growing waves will end up taking part in the turbulent energy transport. However, how these pickup-ion-associated energies involve in turbulent cascade and influence turbulence evolution have yet to be studied. In this work, we study the solar wind turbulence evolution from 1 au to 33 au based on Voyager 2 magnetic field measurements. We study 305 time intervals listed in Pine et al. (2020). In all these time intervals, no ion-scale bumps are present in the turbulent spectra. We find that: (1) The perpendicular and trace power spectra (and ) still follow a Kolmogorov-like spectrum until 33 au while the parallel power spectrum transits from -2 to -5/3 at heliocentric distance R~10 au; (2) At periods 10 s <τ< 500 s, quasi-parallel propagation dominates in 1 au<R<7 au, with quasi-perpendicular propagation gradually emerging at R>5au. For R > 7 au, oblique propagation becomes a primary component. (3) At larger periods of τ>100 s, increases with propagation angle in 1 au<R<5 au, and in contrast decreases with propagation angle at R>5 au due to the enhanced power level at propagation angles smaller than . We suggest that such enhancement may derive from the injection of the wave energy from the pickup ion source into the background tubulent cascade , and the injected wave energy is transferred across scales withou leaving bumps in or .

How to cite: Zhu, X., He, J., Duan, D., and Lin, R.: Evolution of Turbulence Anisotropy in the Outer Heliosphere and Transport of Pickup-ion-associated Energy in Turbulence Channel : Voyager 2 Observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15757, https://doi.org/10.5194/egusphere-egu23-15757, 2023.

EGU23-15770 | Posters on site | ST1.11

Magnetic helicity dynamics in compressible isothermal MHD turbulence 

Jean-Mathieu Teissier and Wolf-Christian Müller

Magnetic helicity dynamics are important in the context of the generation of large scale magnetic structures from small scale fluctuations. Up to the present day, these dynamics have remained largely unexplored in compressible plasmas. We present new results from direct numerical simulations of isothermal magnetohydrodynamic turbulence, with Mach numbers ranging from 0.1 to 10 by employing higher-order numerics. A mechanical driving injects kinetic energy at the largest scales, while a small scale electromotive driving injects helical magnetic fluctuations. A large-scale sink of magnetic energy leads to the formation of a turbulent statistically stationary state, which is analyzed, extending the results on nonlinear cross-scale transfer presented in doi:10.1017/jfm.2021.32 and doi:10.1017/jfm.2021.496.

How to cite: Teissier, J.-M. and Müller, W.-C.: Magnetic helicity dynamics in compressible isothermal MHD turbulence, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15770, https://doi.org/10.5194/egusphere-egu23-15770, 2023.

EGU23-15845 | Posters on site | ST1.11

Stochasticity and fractalityin irregular space plasmas 

Massimo Materassi and Giuseppe Consolini

One of the most relevant feature of turbulent fluids, included Space Plasmas, is the irregularity of the fields defining their local state (for example $\vec{B}$, $\vec{j}$ and $\vec{v}$ in the Solar Wind). In particular, time series of local quantities collected by \emph{in situ} measurements, e.g. by satellites, as well as remote sensing data, e.g. those from trans-medium communications, show scale-dependent statistical behaviour suggesting the local state fields to be better represented as \emph{fractal} or \emph{multi-fractal measures} rather than smooth functions of time and position.
In this presentation, the relationship between those measured fractal properties and the stochastic generalizations of fluid models describing the plasma is traced, suggesting a possible future development of Space Plasma turbulence theory.

How to cite: Materassi, M. and Consolini, G.: Stochasticity and fractalityin irregular space plasmas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15845, https://doi.org/10.5194/egusphere-egu23-15845, 2023.

EGU23-16937 | ECS | Posters on site | ST1.11

Analysis of magnetic helicity generation in MHD-shell model 

Ilyas Abushzada, Egor Yushkov, and Dmitry Sokoloff

The mechanism of stellar large-scale magnetic field formation, including the eleven-year solar cycle, is currently generally understood. In particular, its linear mode, in which the reverse effect of the magnetic field on the velocity field can be neglected. However, the non-linear reverse influence, which stabilize the growing average magnetic field, is not completely clear. The most possible reason of the nonlinear stabilization of this process is assumed the hydrodynamic helicity, but the balance of hydrodynamic and magnetic helicity and its transport along the spectrum remains to be studied. The present report is devoted to this problem. An exponential growth of magnetic energy at sufficiently high magnetic Reynolds numbers can be observed in a random short-correlated plasma flow at small-scales relative the velocity correlation length. Magnetic helicity is generated in this case together with the small-scale energy of magnetic field. And despite the fact that this phenomenon is traditionally studied by using the Kazantsev’s approach, we are trying to recreate this process of small-scale generation by a mhd shell approach, which is more convenient for the subsequent study of the balance and energy/helicity transport from small scales to large ones. To do this, in the complex shell model we add a small magnetic field to the well-established Kolmogorov spectrum and, by observing the exponential growth of magnetic energy on small scales, we compare the generation process with the magnetic small-scale Kazantsev dynamo. We select the correlation time for the velocity field and the working spectral regions to show that, in general, both approaches describe the same process with the same generation rates and scales. Thus, we show that the shell approach can be used for the future study of small-scale energy/helicity transport along the spectrum and for the problems of large-scale stellar dynamo processes stabilization. This work was supported by the BASIS Foundation grant no. 21-1-3-63-1.

How to cite: Abushzada, I., Yushkov, E., and Sokoloff, D.: Analysis of magnetic helicity generation in MHD-shell model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16937, https://doi.org/10.5194/egusphere-egu23-16937, 2023.

EGU23-3017 | ECS | Orals | NP6.2 | Highlight

Energy Conversion and Partition in Plasma Turbulence Driven by Magnetotail Reconnection 

Xinmin Li, Rongsheng Wang, Can Huang, Quanming Lu, and San Lu

A long-outstanding issue in fundamental plasma physics is how magnetic energy is finally dissipated in kinetic scale in the turbulent plasma. Based on the Magnetospheric Multiscale mission data in the plasma turbulence driven by magnetotail reconnection, we establish the quantitative relation between energy conversion (J·E , J is current density and E is electric field) and current density (J). The results show that the magnetic energy is primarily released in the perpendicular directions (up to 90%), in the region with current density less than 2.3 Jrms, where Jrms  is the root mean square value of the total current density J. In the relatively weak current region (< 1.0 Jrms ), the ions get most of the released energy while the largely negative energy conversion rate of the electrons means a dynamo action. In the strong currents (>1.0 Jrms), the ion energization was negligible and the electrons are significantly energized. Moreover, a linearly increasing relationship was established between J·E and J. The observations indicate that ions overall dominate energy conversion in turbulence, but the electron dynamics are crucial for energy conversion in intense currents and the turbulence evolution.

How to cite: Li, X., Wang, R., Huang, C., Lu, Q., and Lu, S.: Energy Conversion and Partition in Plasma Turbulence Driven by Magnetotail Reconnection, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3017, https://doi.org/10.5194/egusphere-egu23-3017, 2023.

EGU23-3604 | ECS | Orals | NP6.2

Swift generator for 3D magnetohydrodynamic turbulence 

Daniela Maci, Rony Keppens, and Fabio Bacchini

Turbulent states of motion are almost unavoidable in fluids, gases, and plasmas. The ubiquitous presence of turbulence largely contributes to the central role that its study holds in many research fields. This work focuses on space and astrophysical plasmas, where magnetohydrodynamic turbulence is observed nearly everywhere. However, it builds on an issue that is shared by all turbulence-related field of studies: direct numerical simulations (DNS), required to verify turbulent states properties such as scaling law behaviors, require substantial computing resources.

The presentation will introduce the audience to BxC[1], an analytic generator of realistic-looking turbulent magnetic fields, that computes 3D O(10003 grid points) solenoidal vector fields in minutes to hours on desktops. The model is inspired by recent developments in 3D incompressible fluid turbulence theory: intermittent, multifractal random fields are generated through non-linear transformations of a Gaussian white noise vector, combined to specifically designed geometrical constructions. Furthermore, the model is implemented starting from a modified Biot-Savart law, which allows for a clear interpretation of the BxC parameters.

The turbulent magnetic field realized with BxC is then compared and validated against a much more computationally expensive DNS in terms of: (i) characteristic sheet-like structures of current density, (ii) volume-filling aspects across current intensity, (iii) power-spectral behaviour, (iv) probability distribution functions of increments for magnetic field and current density, structure functions, spectra of exponents, and (v) partial variance of increments.

 

[1] Durrive, J.-B., Changmai, M., Keppens, R., Lesaffre, P., Maci, D., and Momferatos, G. (2022). Swift generator for three-dimensional magnetohydrodynamic turbulence. Phys. Rev. E, 106:025307

How to cite: Maci, D., Keppens, R., and Bacchini, F.: Swift generator for 3D magnetohydrodynamic turbulence, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3604, https://doi.org/10.5194/egusphere-egu23-3604, 2023.

EGU23-5887 | ECS | Posters on site | NP6.2

Ion Temperature Anisotropy in Plasma Jets 

Louis Richard, Yuri V. Khotyaintsev, Daniel B. Graham, Andris Vaivads, Daniel J. Gershman, and Christopher T. Russell

Magnetotail magnetic reconnection results in fast plasma flows referred to as jets. Reconnection jets are populated with complex non-Maxwellian ion distributions providing a source of free energy for the micro-instabilities, which contribute to the ion heating in the reconnection region. We present a statistical analysis of the ion temperature anisotropy in magnetic reconnection jets using data from the Magnetospheric Multiscale spacecraft. Compared with the quiet plasma in which the jet propagates, we often find anisotropic and non-Maxwellian ion distributions in the plasma jets. We observe magnetic field fluctuations associated with unstable ion distributions, but the wave amplitude is not large enough to scatter ions during the observed lifetime of the jet. Our estimate of the phase-space diffusion due to chaotic and quasi-adiabatic ion motion in the current sheet shows that the diffusion is sufficiently fast to be the main process leading to isotropization.

How to cite: Richard, L., Khotyaintsev, Y. V., Graham, D. B., Vaivads, A., Gershman, D. J., and Russell, C. T.: Ion Temperature Anisotropy in Plasma Jets, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5887, https://doi.org/10.5194/egusphere-egu23-5887, 2023.

Magnetic reconnection interlinks different regions of plasmas by converting magnetic energy into plasma heating and energization of particles. It causes abrupt changes in the temperature, density, field strength and flow speed. The physical mechanism behind charge particle energization during magnetic reconnection is best explained by the concept of double layers (DLs) and associated parallel electric fields. In-situ observations of reconnection sites by Magnetospheric Multi Scale (MMS), THEMIS and FAST have confirmed that charge particle energization in these regions is associated with large parallel electric fields in auroral regions, Earth’s plasma sheet and separatrix region of Earth’s magnetosphere. The reported literature motivated us to investigate double layers and associated electric field at the reported sites by using multi-fluid theory for electron-ion plasma and employing fully nonlinear Sagdeev potential approach. We have considered the ion inertial effect whereas electrons are assumed to be non-Maxwellian following (r, q) distribution function. In particular, parallel electric fields associated with Alfvenic double layer have been investigated at non-Maxwellian effective temperature scales and then compared with the observations. We have seen that the characteristics of DLs associated with the kinetic Alfvén waves are significantly modified due to the nonthermal parameters r and q, propagation angle 𝜃, and Alfvénic Mach number 𝑀A. Our current study supports both the compressive and rarefactive double layer structures.

How to cite: Khalid, S. and Qureshi, M. N. S.: Parallel Electric Field and Double Layers at Non-Maxwellian Effective Temperature Scales in Near Earth Space Plasmas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5905, https://doi.org/10.5194/egusphere-egu23-5905, 2023.

EGU23-6253 | Orals | NP6.2 | Highlight

Turbulent energy transfer and dissipation in the terrestrial magnetosheath 

Zoltan Vörös, Owen Wyn Roberts, Luca Sorriso-Valvo, Emiliya Yordanova, Yasuhito Narita, Rumi Nakamura, and Ferdinand Plaschke

The terrestrial magnetosheath (MS) represents a turbulent, high-beta, compressional, sporadically Alfvenic environment which contains the shocked solar wind (SW) magnetized plasma permeated with waves, instabilities and structures of various origins. In the processes of interaction of the structured SW with the shock and the MS, the electromagnetic, kinetic and thermal energies are transported between locations,  transferred between scales, conversed between each other and finally dissipated. Similarly to the SW case the energy transfer in MS is expected to be manifested in typical scalings seen in power spectral densities of various field and plasma parameters  over the fluid (inertial-range) and kinetic ion-electron scales. However, near the sub-solar dayside MS the inertial-range turbulent cascade is usually absent, while the kinetic range scaling roughly remains the same as in the SW. Observations of short magnetic correlation lengths near the sub-solar MS also confirm the absence of large-scale magnetic fluctuations which could populate the inertial-range of scales. Without the inertial range energy cascade the kinetic range turbulence should exhibit a fast decay downstream of the shock, but it is not observed. We argue that to understand the spectral scalings in the MS the whole energy budget has to be considered including possible nonlocal energy transfer terms. By using MMS data in the MS we show that, when the inertial range is present, the turbulent energy dissipation rate can be estimated by the energy transfer rate from both the Yaglom law and from the pressure-strain interaction term. When the inertial range is absent and the Yaglom law cannot be used,  the dissipation rate can still be estimated by using the pressure-strain term.

How to cite: Vörös, Z., Roberts, O. W., Sorriso-Valvo, L., Yordanova, E., Narita, Y., Nakamura, R., and Plaschke, F.: Turbulent energy transfer and dissipation in the terrestrial magnetosheath, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6253, https://doi.org/10.5194/egusphere-egu23-6253, 2023.

EGU23-6702 | ECS | Orals | NP6.2 | Highlight

Electron-scale reconnecting current sheet formed within the lower hybrid wave-active region of Kelvin-Helmholtz waves 

Kevin Alexander Blasl, Takuma Nakamura, Rumi Nakamura, Adriana Settino, Zoltan Vörös, Martin Hosner, Daniel Schmid, Martin Volwerk, Owen Wyn Roberts, Evgeny Panov, Yi-Hsin Liu, Ferdinand Plaschke, Hiroshi Hasegawa, Julia Stawarz, and Justin Craig Holmes

The Kelvin-Helmholtz instability (KHI) excited at the Earth’s magnetopause has been considered responsible for causing efficient mass and energy transfer across the magnetopause. Theoretical, numerical and observational studies have revealed that the evolution of the KHI and the resulting nonlinear vortex flow involve secondary processes. As a unique case of such multi-scale and inter-process couplings, we recently reported observations of the MHD-scale KH waves and embedded smaller-scale phenomena in data from NASA’s Magnetospheric Multiscale (MMS) mission at the dusk- flank magnetopause during southward interplanetary magnetic field (IMF) conditions. Given quantitative consistencies with corresponding fully-kinetic particle-in-cell (PIC) simulations designed for this event, the MMS observations demonstrate the onset of the Lower-Hybrid Drift Instability (LHDI) during the nonlinear phase of the KHI and the subsequent turbulence and mixing of plasmas near the boundary layer.

In this study, we further explored this southward IMF KHI event and found signatures of magnetic reconnection in an electron-scale current sheet observed in the KH vortex-driven LHDI turbulence. This reconnection event was observed under high guide field conditions and features a super-Alfvénic electron outflow, a Hall perturbation of the magnetic field and enhanced energy conversion. Results from a high-resolution PIC simulation designed for this reconnecting current sheet suggest a highly dynamical current sheet evolution, quantitatively consistent with the observations made by MMS.

In addition, results from statistical studies utilizing data from several KH wave/vortex edge crossings throughout this southward IMF KH event show that the formation of electron-scale current sheets due to the interplay of the KHI and LHDI would be a ubiquitous phenomenon at least under the observed conditions of this magnetopause event and thus an important factor in the study of cross-scale energy transfer of the KHI.

How to cite: Blasl, K. A., Nakamura, T., Nakamura, R., Settino, A., Vörös, Z., Hosner, M., Schmid, D., Volwerk, M., Roberts, O. W., Panov, E., Liu, Y.-H., Plaschke, F., Hasegawa, H., Stawarz, J., and Holmes, J. C.: Electron-scale reconnecting current sheet formed within the lower hybrid wave-active region of Kelvin-Helmholtz waves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6702, https://doi.org/10.5194/egusphere-egu23-6702, 2023.

EGU23-8086 | ECS | Posters on site | NP6.2 | Highlight

Energy conversion by magnetic reconnection in multiple ion temperature plasmas 

Jeremy Dargent, Sergio Toledo-Redondo, Andrey Divin, and Maria Elena Innoncenti

This work investigates the energy transfer in the process of collisionless antiparallel magnetic reconnection and its dependance to the velocity distribution function of the inflowing plasma. We realised two two-dimensional semi-implicit PIC simulations of symmetric reconnection with exactly the same global parameters, but with different distributions of plasma: one simulation is loaded using Maxwellian distributions, while the other is the sum of two Maxwellian distributions, a hot one and a cold one, resulting in a very peaked distribution with large tails. We measure the increase of the bulk and thermal kinetic energies in both simulation for each population and compare it to the loss of magnetic energy through a contour surrounding the ion diffusion region. We show that the global energy budget for ions and electrons does not change depending on the distribution function of the plasma, but also that, when focusing on sub-populations, the hot ion population (i.e. the tail of the distribution) get more thermal energy than the cold ion population (i.e. the core of the distribution).

How to cite: Dargent, J., Toledo-Redondo, S., Divin, A., and Innoncenti, M. E.: Energy conversion by magnetic reconnection in multiple ion temperature plasmas, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8086, https://doi.org/10.5194/egusphere-egu23-8086, 2023.

EGU23-9773 | Posters virtual | NP6.2

Flow Crossover during Collisionless Magnetic Reconnection: A Particle-Labelling Particle-in-Cell Study 

Kittipat Malakit, Theerasarn Pianpanit, Pakkapawn Prapan, David Ruffolo, Peera Pongkitiwanichakul, Michael Shay, Paul Cassak, and Piyawat Suetrong

During 2D magnetic reconnection, plasma is normally understood to flow from one of the inflow sides into the diffusion region and then turn sharply and join the outflow on the same side. Using particle-in-cell simulations with a modification to allow us to label ions and electrons by their initial locations, we find that inflowing plasma does not join the outflow on the same side; instead, plasma crosses to the other inflow side before changing direction to produce an outflow jet. Furthermore, we find that ions and electrons undergo different crossover mechanisms leading to different crossing patterns. The ion crossover occurs more locally within the ion diffusion region whereas the electron crossover occurs over a wider region as its mechanism does not require electrons to pass through the electron diffusion region. This flow crossover occurs both in symmetric reconnection and in a more complex scenario such as a guide-feld asymmetric reconnection, suggesting that it is a general feature of collisionless magnetic reconnection. Recognizing the existence of the flow crossover can be important in improving our understanding of reconnection in many situations. This research has been partially supported by Thailand's National Science and Technology Development Agency (NSTDA): High-Potential Research Team Grant Program (N42A650868), grant MRG6180176 from Thailand Science Research and Innovation, and by a grant from Kasetsart University Research and Development Institute.

How to cite: Malakit, K., Pianpanit, T., Prapan, P., Ruffolo, D., Pongkitiwanichakul, P., Shay, M., Cassak, P., and Suetrong, P.: Flow Crossover during Collisionless Magnetic Reconnection: A Particle-Labelling Particle-in-Cell Study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9773, https://doi.org/10.5194/egusphere-egu23-9773, 2023.

EGU23-10328 | ECS | Posters virtual | NP6.2

Analysis on magnetic field gradients in turbulent magnetosheath by using MMS data 

Yong Ji, Chao Shen, Lan Ma, Nian Ren, and Nisar Ahmad

Magnetic field gradients determine magnetic topological structure and current density in space plasma turbulence. This study uses multi-point method analyze high-quality field and plasma data measured by the Magnetospheric Multiscale (MMS) mission in the turbulent magnetosheath. The statistical properties of the curvature of the magnetic field line and the geometric invariant of the magnetic field gradient tensor are further investigated. The results show that the probability distribution function of curvature has two scaling laws. There is a correlation between large curvatures and pressure anisotropy, indicating the acceleration due to curvature drifts. During strong magnetic field, flux ropes and tubes are the most possible magnetic structures. Statistics in the plane formed by geometrical invariants show that about 23% are force free structures consist of 20.5% flux tubes and 79.5% flux ropes. The remaining actively evolved structures are comprised of 30% flux tubes and 70% flux ropes. Moreover, the conditional average of current density and Lorentz force decomposition in geometrical invariants plane are conducted. Results show that flux ropes carried more current density than flux tubes for same geometrical invariants, and flux ropes tend to associate with magnetic pressure force and flux tubes tend to associate with magnetic tension.

How to cite: Ji, Y., Shen, C., Ma, L., Ren, N., and Ahmad, N.: Analysis on magnetic field gradients in turbulent magnetosheath by using MMS data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10328, https://doi.org/10.5194/egusphere-egu23-10328, 2023.

EGU23-10735 | Orals | NP6.2

Statistics of the high-speed electron flows in the magnetotail 

Huijie Liu, Wenya Li, Binbin Tang, Cecilia Norgren, Daniel Graham, Yuri Khotyaintsev, Daniel Gershman, James Burch, and Chi Wang

High-speed electron flows play an important role in the energy dissipation and conversion in the terrestrial magnetosphere and are widely observed in regions related to magnetic reconnection, e.g., the vicinity of electron diffusion regions (EDRs), and separatrix layers. NASA’s Magnetospheric Multiscale mission was designed to resolve the electron-scale kinetic processes of Earth’s magnetosphere. Here, we perform a systematic survey of high-speed electron flows in the terrestrial magnetotail using the MMS observations from 2017 to 2021. The high-speed electron flows are characterized by electron bulk speeds larger than 5000 km/s. We identified 649 events. Those events demonstrate unambiguous dawn-dusk asymmetry, and 73% of them locate in the dusk magnetotail. The selected events are found in EDRs, the reconnection separatrix boundary layer, and the lobe region. More than 70% of the events are identified in the separatrix boundary layer and the lobe region and are aligned with the ambient magnetic field. 75 cases, with magnetic field magnitude smaller than 5 nT, locate near the plasma-sheet neutral line. Approximately 20 cases among them have EDR signatures, and those high-speed electron flows are directed arbitrarily with respect to the ambient magnetic field. We also show other statistical properties of the events, including electron bulk speed, electron number density, and temperature anisotropy. 

How to cite: Liu, H., Li, W., Tang, B., Norgren, C., Graham, D., Khotyaintsev, Y., Gershman, D., Burch, J., and Wang, C.: Statistics of the high-speed electron flows in the magnetotail, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10735, https://doi.org/10.5194/egusphere-egu23-10735, 2023.

EGU23-11279 | Orals | NP6.2

Electron dynamics in guide-field magnetic reconnection 

Binbin Tang, Hanwen Wang, Wenya Li, Yongcun Zhang, Daniel Graham, Yuri Khotyaintsev, Chunhui Gao, Xiaocheng Guo, and Chi Wang

Magnetic reconnection is a fundamental process that rapidly converts energy from the magnetic field to plasma. Recent studies have shown that a large parallel electric field (E) can appear in guide-field reconnection, and its magnitude can be several times larger than the reconnection electric field. However, the generation of this large E is still not fully understood, and the reaction of electrons to this E has not been fully investigated. In this study, we focus on these issues in a strong guide-field reconnection event (the normalized guide field is ~ 1.5) from Magnetospheric Multiscale (MMS) observations. With the presence of a large E in the electron current sheet, electrons are accelerated when streaming into this E region from one direction, and decelerated from the other direction. Some decelerated electrons can reduce the parallel speed to ~ 0 to form relatively isotropic electron distributions at one side of the electron current sheet, as the estimated acceleration potential (Φ ~ 2 kV) satisfies the relation eΦ ≥ kT, where T is the electron temperature parallel to the magnetic field. Therefore, a large E is generated to balance the parallel electron pressure gradient across the electron current sheet, since electrons at the other side of the current sheet are still anisotropic. Based on these observations, we further show that the electron beta is an important parameter in guide-field reconnection, providing a new perspective to solve the large parallel electric field puzzle in guide-field reconnection.

How to cite: Tang, B., Wang, H., Li, W., Zhang, Y., Graham, D., Khotyaintsev, Y., Gao, C., Guo, X., and Wang, C.: Electron dynamics in guide-field magnetic reconnection, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11279, https://doi.org/10.5194/egusphere-egu23-11279, 2023.

EGU23-11615 | Posters on site | NP6.2

Electron-scale dynamics and generalized Ohm’s law of an MMS X-line encounter on 27 August 2018 

Wenya Li, Binbin Tang, and Chi Wang

Magnetic reconnection is a fundamental process in collisionless space plasma, and the electron-scale kinetic physics at the X line controls how the magnetic field lines break and reconnect. The four spacecraft of the Magnetospheric Multiscale (MMS) mission encountered an X line of symmetric reconnection in the terrestrial magnetotail on 27 August 2018. Here, we present the electron-scale dynamics and the generalized Ohm’s law (GOL) analysis of this case. Its two-dimensional structure, magnetic topology, and electron streamline map are reconstructed based on a time-independent and inertialess form of electron magnetohydrodynamic (eMHD) equation. We map the electron velocity distribution functions (VDFs) along the MMS trajectories through the X line, covering the two-side inflow and reconnected regions, and the typical electron motions for forming the observed VDFs are also presented. The observed reconnection electric field EM is approximately 2-3 mV/m and predominantly balanced by the spatial gradient of the electron pressure off-diagonal term PeMN, which is mostly contributed by the electron meandering motion at the X line. Our results show the electron-scale dynamics and the associated electron VDFs at an X line and their role in the electron force balance.

How to cite: Li, W., Tang, B., and Wang, C.: Electron-scale dynamics and generalized Ohm’s law of an MMS X-line encounter on 27 August 2018, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11615, https://doi.org/10.5194/egusphere-egu23-11615, 2023.

EGU23-11637 | Posters on site | NP6.2

A numerical study of tearing instability growth rate as a function of current sheet thickness in the kinetic regime 

Maria Elena Innocenti, Fulvia Pucci, Elisabetta Boella, Anna Tenerani, and Jeremy Dargent

In this study, we use fully kinetic Particle In Cell (PIC) simulations to investigate numerically the dispersion relation of the tearing instability in the kinetic regime, which is at the moment rather poorly explored by theoretical investigations. To reduce the computational cost of the simulations, we use the the semi-implicit, energy conserving ECsim code (Lapenta et al, 2017), that allows us to step over the smaller scales and fastest frequencies and focus on characteristic scales of interest, with excellent energy conservation.

We run several simulations with current sheets of fixed length. The current sheet half-thickness is progressively increased from $\delta \sim d_i$ to significantly larger. The other simulation parameters are kept identical.

In our simulations, the tearing instability grows without external perturbation from the particle noise of PIC simulations. Later onset times are (predictably) observed when the number of particles per cell is increased.

Several modes grow unstable in each simulation. We plot the growth rates of the unstable modes as a function of the current sheet thickness. We obtain a spread around a curve decreasing with increasing current sheet thickness. 

How to cite: Innocenti, M. E., Pucci, F., Boella, E., Tenerani, A., and Dargent, J.: A numerical study of tearing instability growth rate as a function of current sheet thickness in the kinetic regime, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11637, https://doi.org/10.5194/egusphere-egu23-11637, 2023.

EGU23-12262 | ECS | Orals | NP6.2

Plasma mixing during active Kelvin-Helmholtz instability at the Earth’s magnetopause under different interplanetary magnetic field configurations 

Adriana Settino, Rumi Nakamura, Kevin A. Blasl, Takuma Nakamura, Denise Perrone, Francesco Valentini, Owen Wyn Roberts, Evgeny Panov, Zoltan Vörös, Martin Volwerk, Daniel Schmid, Martin Hosner, Daniel B. Graham, and Yuri V. Khotyaintsev

The Kelvin-Helmholtz (KH) instability is a shear-driven instability commonly observed at the Earth’s magnetopause under different solar wind conditions. The evolution of the KH instability is characterised by the nonlinear coupling of different modes, which tend to generate smaller and smaller vortices along the shear layer. Such a process leads to the conversion of energy due to the large-scale motion of the shear flow into heat contributing to the local heating and the generation of a turbulent environment. On the other hand, it allows the entry of the dense and cold solar wind plasma into the tenuous and hot magnetosphere, thus favoring the mixing of these two different regions.

In this context, we introduce a new quantity, the so-called mixing parameter, which can identify the vortex boundaries and distinguish among different types of KH structures crossed by the spacecraft. The mixing parameter exploits the well distinct particle energies which characterise the magnetosphere and magnetosheath plasmas by using only single-spacecraft measurements [1]. The mixing parameter is therefore used to conduct a statistical analysis of the evolution of KH structures observed by the Magnetospheric Multiscale mission in the near Earth’s environment for two specific interplanetary magnetic field configurations: northward and southward. Moreover, in situ measurements are compared with kinetic KH instability simulations modeling realistic conditions observed by the satellites. The good agreement between synthetic data and in situ observations further strengthen our interpretation of the mixing parameter features and results.

 

[1] Settino, A., et al. (2022) Journal of Geophysical Research: Space Physics, 127, e2021JA029758.

How to cite: Settino, A., Nakamura, R., Blasl, K. A., Nakamura, T., Perrone, D., Valentini, F., Roberts, O. W., Panov, E., Vörös, Z., Volwerk, M., Schmid, D., Hosner, M., Graham, D. B., and Khotyaintsev, Y. V.: Plasma mixing during active Kelvin-Helmholtz instability at the Earth’s magnetopause under different interplanetary magnetic field configurations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12262, https://doi.org/10.5194/egusphere-egu23-12262, 2023.

EGU23-13090 | ECS | Posters on site | NP6.2

The influence of multiscale fractal geometry on the generation of turbulence 

Otman Ben Mahjoub and Aziz Ouadoud

The present research aims to study the influence of multiscale fractal geometry on the generation and decay of turbulence by spaced fractal square grid (SFSG) in order to understand how the turbulent flow is modified when it is generated at different scales. Velocity measurements were made in an open-circuit suction wind tunnel at various positions downstream of the grid in the streamwise and spanwise direction for three different inlet velocities using a constant temperature hot wire anemometer. The SFSG pattern producing a multiscale forcing of velocity is new and is the one used as the basis for this project. It was found that this space-filling grid model with relatively low solidity has the ability to generate turbulence with high turbulence intensity and high Reynolds numbers compared to the turbulence generated by fractal square grid (FSG) and regular grids at the same flow velocity. A more comprehensive understanding of this type of multiple length scales in momentum and energy transport has a key role to understand the analysis of structural implications due to the pollutant dispersion in the atmosphere.

How to cite: Ben Mahjoub, O. and Ouadoud, A.: The influence of multiscale fractal geometry on the generation of turbulence, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13090, https://doi.org/10.5194/egusphere-egu23-13090, 2023.

EGU23-14458 | ECS | Posters on site | NP6.2

Modelling magnetic turbulence with log-normal intermittency by continuous cascades 

Jeremiah Lübke, Frederic Effenberger, Horst Fichtner, and Rainer Grauer

The transport of cosmic rays in turbulent magnetic fields is commonly investigated by solving the Newton-Lorentz equation of test particles in synthetic turbulence fields. These fields are typically generated from superpositions of Fourier modes with prescribed power spectrum and uncorrelated random phases, bringing the advantage of covering a wide range of turbulence scales at manageable computational effort. However, almost all of these models to date only account for second-order Gaussian statistics and thus fail to include intermittent features. Recent observations of the solar wind suggest that astrophysical magnetic fields are strongly non-Gaussian, and the question of how such higher-order statistics impact cosmic ray transport has only received limited attention. To address this, we present an algorithm for generating synthetic turbulence based on Kolmogorov’s log-normal model of intermittency. It generates a divergence-free magnetic field by computing the curl of a vector potential, which in turn is obtained from an inverse wavelet transform of a continuous log-normal cascade process. We investigate the statistics of the generated fields, show that anomalous scaling properties are accurately reproduced and discuss implications on cosmic ray transport. *Supported by DFG (SFB 1491)

How to cite: Lübke, J., Effenberger, F., Fichtner, H., and Grauer, R.: Modelling magnetic turbulence with log-normal intermittency by continuous cascades, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14458, https://doi.org/10.5194/egusphere-egu23-14458, 2023.

EGU23-15616 | Orals | NP6.2

On the nature of electric field fluctuations in the near-Sun solar wind and its implication for the turbulent energy transfer at ion and electron scales 

Luca Franci, Emanuele Papini, Daniele Del Sarto, Alfredo Micera, Julia Stawarz, Tim Horbury, Giovanni Lapenta, Harry Lewis, Chadi Salem, Simone Landi, Petr Hellinger, Lorenzo Matteini, Antonio Cicone, Mirko Piersanti, Maria Elena Innocenti, Milan Maksimovic, and David Burgess

We model plasma turbulence in the near-Sun solar wind by means of a high-resolution fully kinetic simulation initialised with average plasma conditions measured by Parker Solar Probe during its first solar encounter. Once turbulence is fully developed, the power spectra of the plasma and electromagnetic fluctuations exhibit clear power-law intervals down to sub-electron scales. Our simulation models the electron-scale electric field fluctuations with unprecedented accuracy. This allows us to perform the first detailed analysis of the different terms of the electric field in the generalised Ohm's law (MHD, Hall, and electron pressure terms) at ion and electron scales, both in physical space and in Fourier space. Such analysis suggests rewriting the Ohm’s law in a different form, which disentangles the contribution of different underlying plasma mechanisms, characterising the nature of the electric field fluctuations in the different range of scales. This provides a new insight on how energy in the turbulent electromagnetic fields is transferred through ion and electron scales and seems to favour the role of pressure-balanced structures versus waves. We finally test our assumptions and numerical results by means of a statistical analysis using magnetic field, electric field, and electron density data from Solar Orbiter and Parker Solar Probe. Preliminary results show good agreement with our theoretical expectations inspired by our simulation.

How to cite: Franci, L., Papini, E., Del Sarto, D., Micera, A., Stawarz, J., Horbury, T., Lapenta, G., Lewis, H., Salem, C., Landi, S., Hellinger, P., Matteini, L., Cicone, A., Piersanti, M., Innocenti, M. E., Maksimovic, M., and Burgess, D.: On the nature of electric field fluctuations in the near-Sun solar wind and its implication for the turbulent energy transfer at ion and electron scales, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15616, https://doi.org/10.5194/egusphere-egu23-15616, 2023.

EGU23-15797 | Posters on site | NP6.2 | Highlight

Stability properties of a new anisotropic current sheet equilibrium for planetary magnetotails 

Patricio A. Munoz, Xiaowei Zhou, and Jörg Büchner

Current sheets are the fundamental structures that store magnetic energy in astrophysical plasmas, such as planetary magnetospheres and solar flares. This free energy can then be explosively released by magnetic reconnection. This process has been traditionally modeled by highly idealized models such as the so-called Harris current sheet equilibrium. But recently, a new class of current sheet equilibrium has been analytically  developed, which takes into account several features of recently observed current sheets in planetary magnetotails. Those features include an embedded multi-layer structure, electron temperature anisotropy and a non-linear magnetic field profile in the (inner) electron inner layer which also includes a normal magnetic field component.
Here we present the analysis of the so-far unknown stability properties of this new current sheet equilibrium by means of fully kinetic Particle-in-Cell (PIC) numerical simulations. We used parameters appropriate for the current sheets in diverse planetary magnetotails.
Our results allow us to make more realistic predictions concerning the development of magnetic reconnection in those magnetotails compared to the standard Harris current sheet models.

How to cite: Munoz, P. A., Zhou, X., and Büchner, J.: Stability properties of a new anisotropic current sheet equilibrium for planetary magnetotails, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15797, https://doi.org/10.5194/egusphere-egu23-15797, 2023.

EGU23-16725 | Orals | NP6.2

Investigating the interactions of alpha particles in collisionless oblique heliospheric shocks 

Leon Ofman, Lynn B Wilson, Teresa Nieves-Chinchilla, Lan Jian, and Adam Szabo

Heliospheric shocks associated with interplanetary coronal mass ejections (ICMEs) were observed by Wind, and DSCOVR at L1, STEREO spacecraft at ~1AU, and recently by the Parker Solar Probe in the inner heliosphere. The magnetic structure and the downstream magnetic oscillations were detected by Wind with 10.9 samples/s and DSCOVR with 50 samples/s. However, the velocity distributions of the protons are available at much lower cadence, and the potentially important interaction between  the alpha particles and  the heliospheric shocks are difficult to obtain directly from present data. Since the alpha particles in the solar wind are the second most abundant ion that can carry significant energy, momentum and mass flux of the solar wind, the alphas can significantly affect the propagation of these shocks. Recently, using hybrid-(PIC) models we studied the effects of alpha particles on the structure and magnetic oscillations of oblique high Mach number heliospheric shocks, and found that the magnetic and density structures of these shocks are significantly affected by the alpha particles with typical solar wind relative abundances. Here, we extend the study and report the results of new hybrid models of oblique shocks guided by observations. We investigate the typical observed relative solar wind abundances of alphas, Mach numbers, and shock normal directions, and compare the results for the various shock parameters. We model the effects of alpha particles properties on the shock ramp, wake, and downstream oscillations and study the properties of proton and alpha particle velocity distribution functions (VDFs) and the kinetic waves downstream of the shocks in the inner heliosphere. We expand the model and study for the first time the effects of relative streaming of proton-alpha ion populations as well as the ion anisotropies on the shock propagation. We investigate the effects of the ion kinetic properties on the heliospheric shock structures and discuss how the modeling results can improve the interpretation of spacecraft observations of these shocks. 

How to cite: Ofman, L., Wilson, L. B., Nieves-Chinchilla, T., Jian, L., and Szabo, A.: Investigating the interactions of alpha particles in collisionless oblique heliospheric shocks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16725, https://doi.org/10.5194/egusphere-egu23-16725, 2023.

EGU23-16954 | ECS | Posters virtual | NP6.2 | Highlight

On the Effect of Driving Turbulence on Magnetic Reconnection: A Particle-In-Cell Simulation Study 

Jeffersson Andres Agudelo Rueda, Yi-Hsin Liu, and Kai Germaschewski

Energy dissipation in collisionless plasmas is one of the most outstanding open questions in plasma physics. Magnetic reconnection and turbulence are two phenomena that can produce the right conditions for energy dissipation. These two phenomena are closely related to each other in a wide range of plasmas. Turbulent fluctuations can emerge in critical regions of reconnection events, and magnetic reconnection can occur as a product of the turbulent cascade. Moreover, the presence of a turbulent field can affect the onset and evolution of magnetic reconnection. In this study, we perform 2D and 3D particle-in-cell simulations of a reconnecting Harris current sheet in the presence of turbulent fluctuations to explore the effect of turbulence on the reconnection process in collisionless plasmas. We use the Langevin antenna method to drive turbulence in the reconnecting magnetic field. We compare our results with existing theories.

How to cite: Agudelo Rueda, J. A., Liu, Y.-H., and Germaschewski, K.: On the Effect of Driving Turbulence on Magnetic Reconnection: A Particle-In-Cell Simulation Study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16954, https://doi.org/10.5194/egusphere-egu23-16954, 2023.

EGU23-17214 | Posters on site | NP6.2 | Highlight

Magnetic reconnection in the solar wind: Filamentary currents in a multi-layered exhaust region at an ICME sheath—ejecta boundary 

Matti Ala-Lahti, Tuija Pulkkinen, Julia Ruohotie, Mojtaba Akhavan-Tafti, Simon Good, and Emilia Kilpua

In the solar wind, a bifurcated current sheet is often observed in a reconnection outflow region as predicted by the original Petchek reconnection model, with the detailed exhaust structure becoming more complex when asymmetries between reconnecting plasmas are present. Here we present the first multi-spacecraft mission in-situ observations of a solar wind reconnection exhaust populated with filamentary (Hall) currents at an interplanetary coronal mass ejection (ICME) sheath—ejecta boundary. At the ICME sheath—ejecta boundary, asymmetric inflow conditions control reconnection, a relatively hot and dense plasma of the sheath coupling with the sparse low-beta ejecta plasma. These novel high-resolution observations demonstrate a multi- layered exhaust, and speak for the opportunities that future missions, such as HelioSwarm, and Parker Solar Probe and Solar Orbiter open for investigating magnetic reconnection in the solar wind.

How to cite: Ala-Lahti, M., Pulkkinen, T., Ruohotie, J., Akhavan-Tafti, M., Good, S., and Kilpua, E.: Magnetic reconnection in the solar wind: Filamentary currents in a multi-layered exhaust region at an ICME sheath—ejecta boundary, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17214, https://doi.org/10.5194/egusphere-egu23-17214, 2023.

ST2 – Magnetosphere

EGU23-1159 | ECS | Posters on site | ST2.1

Reconstruction of Mercury’s internal magnetic field beyond the octupole 

Simon Töpfer, Ida Oertel, Vanita Schiron, Yasuhito Narita, Karl-Heinz Glassmeier, Daniel Heyner, Patrick Kolhey, and Uwe Motschmann

The reconstruction of Mercury’s internal magnetic field enables us to take a look into the inner heart of Mercury. In view of the BepiColombo mission, Mercury’s magnetosphere is simulated using a hybrid plasma code, and the
multipoles of the internal magnetic field are estimated from the virtual spacecraft data using three distinct reconstruction methods: the truncated singular value decomposition, the Tikhonov regularization and Capon’s minimum variance projection. The study shows that a precise determination of Mercury’s internal field beyond the octupole up to the dotriacontapole (fifth degree of the multipole expansion) is possible. Especially, Capon’s method provides the most accurate inversion result compared to the Tikhonov regularization and the truncated singular value decomposition.

How to cite: Töpfer, S., Oertel, I., Schiron, V., Narita, Y., Glassmeier, K.-H., Heyner, D., Kolhey, P., and Motschmann, U.: Reconstruction of Mercury’s internal magnetic field beyond the octupole, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1159, https://doi.org/10.5194/egusphere-egu23-1159, 2023.

EGU23-1189 | Orals | ST2.1

Magnetospheric response to southward IMF turning: insights from global models and data analysis 

Andrey Samsonov, Natalia Buzulukova, Stephen Milan, Tianran Sun, and Graziella Branduardi-Raymont

We study the magnetospheric response to solar wind discontinuities with a southward interplanetary magnetic field (IMF) turning. We find two events characterized by a strong positive IMF Bz before the discontinuity and a strong negative Bz after the discontinuity. The magnetosphere stays in quiet conditions until the southward turning in both cases, then the dayside reconnection starts and the electromagnetic energy is accumulated in the magnetotail. We simulate these cases using several MHD models and compare numerical predictions of the global parameters such as the magnetopause standoff distance, open flux in the polar cap, auroral indices, and cross polar cap potential. We also make several runs of one model with different spatial resolutions and ionospheric conductivities. Summarizing this study, we discuss the differences between the MHD models and speculate about the reasons why one model is able to better predict observations than the other. We also discuss the reasons for different magnetospheric responses observed in two cases.

How to cite: Samsonov, A., Buzulukova, N., Milan, S., Sun, T., and Branduardi-Raymont, G.: Magnetospheric response to southward IMF turning: insights from global models and data analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1189, https://doi.org/10.5194/egusphere-egu23-1189, 2023.

EGU23-1390 | ECS | Orals | ST2.1 | Highlight

First results on global hybrid-Vlasov magnetospheric simulations with a coupled ionosphere 

Yann Pfau-Kempf, Urs Ganse, Konstantinos Papadakis, Markku Alho, Markus Battarbee, Giulia Cozzani, Maxime Dubart, Harriet George, Evgeniy Gordeev, Maxime Grandin, Konstantinos Horaites, Leo Kotipalo, Jonas Suni, Vertti Tarvus, Fasil Tesema, Lucile Turc, Ivan Zaitsev, Hongyang Zhou, and Minna Palmroth

Vlasiator, the global hybrid-Vlasov model of the terrestrial magnetosphere, now features a coupled ionosphere model replacing the previous, perfectly conducting inner boundary. Following a well-established approach, densities, temperatures and field-aligned currents are mapped along the geomagnetic dipole field down to an ionospheric grid. Height-integrated Hall and Pedersen conductivities are computed using a model atmospheric profile based on the NRLMSIS model in order to solve for the ionospheric potential. Its gradient is then mapped back to the hybrid-Vlasov simulation domain, yielding an electric field and a resulting EXB drift affecting the plasma at the boundary.

We present an overview of this new coupled ionosphere module as well as highlights from the first large-scale magnetospheric simulation runs performed with it. In particular, we compare the global behaviour of the magnetosphere under steady southward interplanetary magnetic field driving using the perfectly conducting or coupled ionosphere boundary models.

How to cite: Pfau-Kempf, Y., Ganse, U., Papadakis, K., Alho, M., Battarbee, M., Cozzani, G., Dubart, M., George, H., Gordeev, E., Grandin, M., Horaites, K., Kotipalo, L., Suni, J., Tarvus, V., Tesema, F., Turc, L., Zaitsev, I., Zhou, H., and Palmroth, M.: First results on global hybrid-Vlasov magnetospheric simulations with a coupled ionosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1390, https://doi.org/10.5194/egusphere-egu23-1390, 2023.

EGU23-1632 | Orals | ST2.1

Solar Cycle Variation of Energetic Neutral Atoms in the Subsolar Magnetosheath based on IBEX Observations 

Justyna M. Sokol, Michael Starkey, Maher Dayeh, Stephen Fuselier, Steve Petrinec, David McComas, Nathan Schwadron, Jamey Szalay, and Keiichi Ogasawara

The in-ecliptic solar wind influences the boundaries of the Earth’s magnetosphere, e.g., by controlling the distances of the magnetopause and bow shock. The exospheric neutral hydrogen has been measured up to the Moon’s orbit. The charge exchange between the solar wind protons and the neutral geocoronal hydrogen creates an energetic neutral atom (ENA). The field-of-view of the IBEX-Hi instrument onboard the Interstellar Boundary Explorer (IBEX) encompasses various portions of the Earth’s magnetosphere during the year, including the subsolar point. Recently, Sokół et al. 2021 (ApJ 922 250) reported periodic, solar cycle enhancements of the solar wind dynamic pressure. We study the solar cycle evolution of the H ENA flux in the subsolar magnetosheath based on the IBEX measurements. We observed an enhancement of the ENA flux after the maximum of solar activity. We also analyze how the ENA flux varies with the solar wind parameters. We observe positive correlations with the solar wind dynamic pressure in the energy range from 0.7 to 4.3 keV and also opposite variations in correlation coefficients between the ENA flux and the solar wind speed and density.

How to cite: Sokol, J. M., Starkey, M., Dayeh, M., Fuselier, S., Petrinec, S., McComas, D., Schwadron, N., Szalay, J., and Ogasawara, K.: Solar Cycle Variation of Energetic Neutral Atoms in the Subsolar Magnetosheath based on IBEX Observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1632, https://doi.org/10.5194/egusphere-egu23-1632, 2023.

EGU23-3702 | Orals | ST2.1

Systemic solar wind condition causing distortion of the predicted magnetic reconnection location at the dayside magnetopause as observed by MMS 

Karlheinz Trattner, Stephen Fuselier, Steven Petrinec, Jim Burch, and Robert Ergun

Across the Earth’s magnetopause, magnetic reconnection has been observed as either the anti-parallel and/or component reconnection scenarios. The magnetic reconnection location prediction model known as the Maximum Magnetic Shear model combines these two scenarios and predicts long reconnection lines crossing the dayside magnetopause along a ridge of maximum magnetic shear. The model has been tested and validated and predicts the dayside reconnection location correctly for 84% of the events. 
Observed magnetic reconnection events for which the model fails share common characteristics, which indicates that for these conditions additional factors have an influence on the location of the dayside reconnection line. One of these specific conditions results in a set of so-called Knee events for which the anti-parallel reconnection region lines up along the draped Interplanetary Magnetic Field (IMF) lines. For these events, magnetic reconnection remains in the anti-parallel reconnection region as long as it is crossed by the draped IMF. Compared to the usual events, this effect results in a deflection of the connection points between the anti-parallel and component reconnection regions (known as anchor points). This study investigates if the location of the entire component reconnection line or only the anchor points are affected by this deflection.  Using two Knee events with confirmed magnetic reconnection location observed by MMS, this study describes how the entire component reconnection line across the dayside magnetopause is deflected if the relative magnetic shear between the maximum magnetic shear location and the deflected magnetic shear location is less than ~5°. 

How to cite: Trattner, K., Fuselier, S., Petrinec, S., Burch, J., and Ergun, R.: Systemic solar wind condition causing distortion of the predicted magnetic reconnection location at the dayside magnetopause as observed by MMS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3702, https://doi.org/10.5194/egusphere-egu23-3702, 2023.

At least four spacecraft are essential to investigate physical processes in space plasmas. CLUSTER was the first four-spacecraft mission orbiting the Earth, during its life time the size of the tetrahedron has been adjusted between hundred to thousands of kilometers accordingly to various scientific objectives. The size of MMS, the second four-spacecraft mission, is smaller. In the barycentric formalism [1, chapter 14] reciprocal vectors of the tetrahedron play a prominent role for estimating field gradients and analysing the propagation of waves or discontinuities. The method of least squares [1, chapter 12] underlines also the importance of the reciprocal vectors and both methods are identical  for four spacecraft [1, chapter 15], nevertheless, meanwhile the barycentric approach is restricted to four spacecraft, the least squares approach is applicable to any number N of spacecraft, and more, weighted least squares offer a possibility of optimization. Generalized reciprocal vectors for N spacecraft with arbitrary weights have been defined [2] and it was announced [3] that gradients of fields estimated from CLUSTER or MMS observations could be improved by an appropriate choice of weights ; this is wrong, we hereby demonstrate that for N=4 the estimated gradient of a vector field is independant of the weights. This unfortunate false announcement was due to a programming error: an erratum has been recently presented [4]. Discriminating between synchronous and asynchronous measurements by the constellation helps clarifying the tools and their uses. Synchronous data which gather observations of the same vector field by all spacecraft at the same time are used to estimate the spatial gradient of the field, meanwhile asynchronous data gathering observations of the same field made by the spacecraft at different times are used to estimate wave vectors or the propagation of discontinuities. The generalized synchronous position tensor R1, built from the vertices of the constellation, is introduced to analyze synchronous data, meanwhile the generalized asynchronous position tensor R2, built from the couples of vertices of the constellation, is introduced to analyze asynchronous data. It worth noticing that the synchronous analysis can be optimized only for N > 4 and by contrast the asynchronous analysis for any number N of spacecraft. The corresponding generalized synchronous and asynchronous reciprocal vectors q are defined by applying the inverses Q1 and Q2 of R1 and R2 to the position vectors, and their properties are demonstrated. We also give in tensor form the estimated gradient of a vector field satisfying the solenoidal condition, initially given by components in[1, chapter 12] and we discuss briefly the aliasing of waves by the constellation, initially adressed for a tetrahedron in [1, chapter 14].

References

  • Analysis Methods for Multi-Spacecraft Data, ISSI Scientific Report SR-001, Eds. G. Paschmann and P.W. Daly, 1998.
  • Multi-Spacecraft Analysis Methods Revisited, ISSI Scientific Report SR-008, Eds. G. Paschmann and P.W. Daly, 2008.
  • Chanteur, G.M., Abstract D3.2-0004-18 Optimal Field Gradients Derived From Multi-Spacecraft Observations, Scientific Assembly Abstracts, p1243, COSPAR 2018 Pasadena, California, USA.
  • Chanteur, G.M., CLUSTER 22nd Birthday Workshop, November 7- 11, 2022, ESOC, Darmstadt, Germany

How to cite: Chanteur, G. M.: Reciprocal Vectors of an Arbitrary Constellation of Spacecraft for Estimating Gradients and Wave Vectors, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4486, https://doi.org/10.5194/egusphere-egu23-4486, 2023.

Magnetohydrodynamic (MHD) wave theory states that fast magnetosonic waves should have correlated fluctuations in the compressional magnetic field and the plasma density / pressure. Anticorrelation, on the other hand relates either to the slow magnetosonic or mirror modes. These classic results are often used as a diagnostic in waves observed by spacecraft throughout the heliosphere. However, it is important to recognise that they are derived under the assumption of a homogeneous background plasma. Planetary magnetospheres are, in contrast, highly inhomogeneous. When allowing for a non-uniform background, the linearised MHD equations for density and pressure perturbations include terms due to the intrinsic compression associated with the wave as well as advection of plasma parcels with different background values. We argue that these two effects can compete and result in anticorrelation between the density and magnetic field, particularly when the scale of the inhomogeneity is shorter than that of the wave. We demonstrate examples of this anticorrelation applied to fast-mode magnetopause surface waves in both analytic MHD theory and a global MHD simulation. Finally, methods which identify and allow for these effects in satellite observations are discussed.

How to cite: Archer, M., Southwood, D., and Hartinger, M.: Anticorrelation of density and magnetic field in a fast magnetosonic mode: The case of surface waves in an inhomogeneous magnetosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5992, https://doi.org/10.5194/egusphere-egu23-5992, 2023.

EGU23-6231 | Posters on site | ST2.1 | Highlight

A statistical study: Relations Between the Directional Changes in Solar Wind Flow and Magnetotail Response 

Dana Saxonbergová and Zoltán Vörös

We explore relationship between the interplanetary magnetic field configuration and the direction of the solar wind flow analyzing few substorm onset lists, produced by different methods over the few years.  We investigate the impact of upstream conditions, such as the interplanetary magnetic field (IMF) configuration and  the changing direction of the solar wind flow on the occurrence of substorms by using substorm onset lists between time1-time2. Large directional changes in the solar wind flow can result in large-scale windsock motions and current sheet thinnings forcing magnetic reconnection to occur in magnetospheric tail, which consequently can lead to substorm onset. Magnetic reconnection is a process, which can explain fast and energetic releases of plasmas in the tail during southward oriented IMF, leading to energetic substorms. However, it is more difficult to explain substorms which are associated with northward oriented IMF. Here we aim to analyse substorms associated with northward oriented IMF with the additional challenge to understand whether the substorm onsets are externally triggered by some upstream conditions or internally initiated by some instabilities in the magnetotail, observed for example during northward oriented interplanetary magnetic field i.e. in the time when there is no significant flux transfer. For our analysis we use concurrent OMNI data of solar wind, substorm databases, Geotail, THEMIS satellite data and ground base data.

How to cite: Saxonbergová, D. and Vörös, Z.: A statistical study: Relations Between the Directional Changes in Solar Wind Flow and Magnetotail Response, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6231, https://doi.org/10.5194/egusphere-egu23-6231, 2023.

EGU23-6951 | ECS | Orals | ST2.1

Study of a dayside magnetopause reconnection event detected by MMS related to a large-scale solar wind perturbation and magnetospheric cold ions 

Mohammed Baraka, Olivier Le Contel, Patrick Canu, Soboh Alqeeq, Mojtaba Akhavan-Tafti, Alessandro Retino, Thomas Chust, Emanuele Cazzola, Dominique Fontaine, Sergio Toledo-Redondo, Jeremy Dargent, Giulia Cozzani, and Cecilia Norgren and the MMS Team

Magnetic reconnection is a fundamental process that is ubiquitous in the universe and allows the conversion of magnetic field energy into heating and acceleration of plasma. 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 detected by the Magnetospheric Multiscale mission (MMS) on 21 October 2015 around 04:40 UT far from the diffusion regions and related to a large-scale solar wind (SW) perturbation impacting the Earth’s magnetosphere. Based on OMNI data, the event impacting the Earth’s magnetosphere is ahead of weak Stream Interacting Region (SIR) (SW beta≈7 and Alfvénic Mach number≈15) where the averaged density of solar wind is about ~20 cm-3 (compared with average SW density ~3-10 cm-3). On one hand, the magnetosheath (MSH) density measured by MMS just after the crossing of the magnetosphere separatrix layer (identified by the large decrease of energetic electrons fluxes) is very large ~95 cm-3 (compared with average MSH density ~20 cm-3). In such a condition, we show that the current density at this separatrix is dominated by the ion diamagnetic current. On the other hand, cold ions are detected close to the magnetic reconnection separatrix layer on the magnetosphere side. Their origin and impact on the ongoing reconnection process are investigated/discussed. The drifting cold ions and the presence of a guide field have significant effects on the orientation of the electric field normal to the magnetopause.

How to cite: Baraka, M., Le Contel, O., Canu, P., Alqeeq, S., Akhavan-Tafti, M., Retino, A., Chust, T., Cazzola, E., Fontaine, D., Toledo-Redondo, S., Dargent, J., Cozzani, G., and Norgren, C. and the MMS Team: Study of a dayside magnetopause reconnection event detected by MMS related to a large-scale solar wind perturbation and magnetospheric cold ions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6951, https://doi.org/10.5194/egusphere-egu23-6951, 2023.

EGU23-7205 | Posters virtual | ST2.1

Constellation of radiation belts survey (CORBES) a COSPAR small satellite constellation survey program for Earth’s radiation belt 

Xiaochao Yang, Lei Dai, Ji Wu, Wen Li, Yoshizumi Miyoshi, Rumi Nakamura, Minna Palmroth, Mohammad Ebrahimi, Li Deng, and Yulun Li

A COnstellation of Radiation BElt Survey (CORBES) program is proposed by the Sub-Group on Radiation Belt (SGRB) of TGCSS, COSPAR, which is in pursuit of the goal of SGRB, focusing on the implementation of a Small/CubeSats constellation mission for radiation belt exploration. Basing on a general review of the status quo of research on the Earth’s radiation belts dynamics and the unresolved scientific issues, the scientific object and observation requirements of CORBES are proposed. The CORBES program is expected to have a constellation of 10-plus small/ CubeSats to take an ultra-fast survey of the Earth’s radiation belt. The general science goal for CORBES is to investigate two groups of physical processes related to the radiation belts: wave-particle interactions and radial transport. This program is an international multilateral cooperation mission, an open and sharing data policy will be implemented. The data set of observations will be shared within the contributors of the constellation and the broad research community at large, then would be of great use for comprehensively understanding the dynamics of magnetospheric energetic populations and developing more standard models of the Earth’s radiation belts. Furthermore, from the application perspective, the ultra-fast survey of the radiation belt could serve as an important facility for monitoring space weather of the Earth as well.

How to cite: Yang, X., Dai, L., Wu, J., Li, W., Miyoshi, Y., Nakamura, R., Palmroth, M., Ebrahimi, M., Deng, L., and Li, Y.: Constellation of radiation belts survey (CORBES) a COSPAR small satellite constellation survey program for Earth’s radiation belt, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7205, https://doi.org/10.5194/egusphere-egu23-7205, 2023.

EGU23-7257 | Posters on site | ST2.1 | Highlight

Energy Conversion Associated with Flux Transfer Events at Earth’s Magnetopause 

Souhail Dahani, Benoit Lavraud, Vincent Génot, Sergio Toledo-Redondo, Rungployphan Kieokaew, Naïs Fargette, Daniel Gershman, Barbara Giles, Roy Torbert, and Jim Burch

Flux Transfer Events (FTEs) are transient phenomena generated at the dayside magnetopause as a result of magnetic reconnection. FTEs have a significant role in the transfer of momentum and energy into the magnetosphere. We study here, in a multifluid framework, how the energy is converted within FTEs and their surrounding plasma. In particular we investigate how the plasma gains or loses kinetic energy through electric and/or pressure gradient terms. We also investigate the terms that control how the internal energy of the plasma is gained or dissipated through the pressure work term. Using observations from Magnetospheric MultiScale (MMS), we perform a statistical study based on an existing FTE catalog (Fargette et al., 2020). We analyze FTEs with or without internal current sheets. We discuss the contribution of the different terms in the energy conversion process separately for ions and electrons and as a function of location within the FTE. We analyze and compare the results found for FTEs’ intervals with magnetosheath intervals (Wang et al. 2021), taking into account their locations, using probability distribution functions of the various energy terms measured in each interval. This work contributes to a better understanding of energy conversion processes associated with FTEs at the magnetopause.

How to cite: Dahani, S., Lavraud, B., Génot, V., Toledo-Redondo, S., Kieokaew, R., Fargette, N., Gershman, D., Giles, B., Torbert, R., and Burch, J.: Energy Conversion Associated with Flux Transfer Events at Earth’s Magnetopause, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7257, https://doi.org/10.5194/egusphere-egu23-7257, 2023.

EGU23-7317 | Orals | ST2.1

Two classes of magnetotail Dipolarization Fronts observed by MagnetosphericMultiscale Mission: A statistical overview 

Soboh Alqeeq, olivier Le Contel, patrick Canu, Alessandro Retinò, Thomas Chust, Laurent Mirioni, Alexandre Chuvatin, Rumi Nakamura, Narges Ahmadi, Frederick Wilder, Daniel Gershman, Yuri Khotyaintsev, Per Arne Lindqvist, Robert Ergun, James Burch, Roy Torbert, Stephen Fuselier, Christopher Russell, Hanying Wei, and Robert Strangeway and the MMS team

We carried out a statistical study of 132 Dipolarization Fronts (DFs) events detected by the Magnetospheric Multiscale mission (MMS) during the full 2017 Earth’s magnetotail season. We found that two DF classes can be distinguished: class I (74.4%) corresponds to the standard DF properties and energy dissipation whereas a new class II (25.6%), which includes the six DF discussed in S. Alqeeq et al. 2022, corresponds to a bump of the magnetic field associated with a minimum of the ion and electron pressures and a reversal of the energy conversion process. For both classes we found that ions are mostly decoupled from the magnetic field by the Hall fields. The electron pressure gradient term is also contributing to the ion decoupling and likely responsible for an electron decoupling at DF. Both DF classes show that the energy conversion process in the spacecraft frame is driven by the diamagnetic current dominated by the ion pressure gradient. In the fluid frame, it is driven by the electron pressure gradient. In addition, we have shown that the energy conversion processes are not homogeneous at the electron scale mostly due to the variations of the electric fields for both DF classes.

How to cite: Alqeeq, S., Le Contel, O., Canu, P., Retinò, A., Chust, T., Mirioni, L., Chuvatin, A., Nakamura, R., Ahmadi, N., Wilder, F., Gershman, D., Khotyaintsev, Y., Lindqvist, P. A., Ergun, R., Burch, J., Torbert, R., Fuselier, S., Russell, C., Wei, H., and Strangeway, R. and the MMS team: Two classes of magnetotail Dipolarization Fronts observed by MagnetosphericMultiscale Mission: A statistical overview, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7317, https://doi.org/10.5194/egusphere-egu23-7317, 2023.

EGU23-7930 | ECS | Orals | ST2.1 | Highlight

Electron diffusion region embedded in a dipolarization front – an MMS/Cluster conjunction event 

Martin Hosner, Rumi Nakamura, Daniel Schmid, Takuma Nakamura, Evgeny V. Panov, Martin Volwerk, Zoltan Vörös, Owen W. Roberts, Kevin A. Blasl, Adriana Settino, Daniil Korovinskiy, Andrew T. Marshall, and Richard E. Denton and the MMS and Cluster Team

Magnetic reconnection, a key energy conversion process in the Earth’s magnetosphere, has extensively been studied during the last few decades. Multi-point missions such as Cluster or Magnetospheric Multiscale (MMS) showed that magnetic reconnection takes place not only at large-scale stable magnetopause or magnetotail current sheets but also in transient localized current sheets.

Here, we revisit the Dipolarization Front (DF) event, observed by the MMS spacecraft on September 08, 2018/14:51:30 UT in the Earth’s magnetotail. Previous studies reported that this DF shows a strong non-ExB type electron flow and a crescent-shaped distribution function, suggesting that this DF hosts an electron diffusion region (Marshall et al. JGR, 2020).

To further characterize this special event, we (1) use conjunction observations of the MMS and Cluster spacecraft to investigate the event in the context of large scales and (2) apply the polynomial magnetic field reconstruction technique by Denton et al. (JGR, 2020) to characterize the embedded electron current sheet including its velocity and the X-line exhaust opening angle. 

How to cite: Hosner, M., Nakamura, R., Schmid, D., Nakamura, T., Panov, E. V., Volwerk, M., Vörös, Z., Roberts, O. W., Blasl, K. A., Settino, A., Korovinskiy, D., Marshall, A. T., and Denton, R. E. and the MMS and Cluster Team: Electron diffusion region embedded in a dipolarization front – an MMS/Cluster conjunction event, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7930, https://doi.org/10.5194/egusphere-egu23-7930, 2023.

EGU23-8054 | Orals | ST2.1 | Julius Bartels Medal Lecture

From Geomagnetism and Space Science to Space Weather 

Hermann Opgenoorth

Early studies of “geo-magnetism” dealt with the understanding of long-term developments and short-term disturbances in the geo-magnetic field as measured by magnetometers on ground level. Soon after the IGY the concept of several co-existing and globally or locally interacting ionospheric current systems (DP1 & 2) was born. Both systems seemed to respond differently to solar wind driving conditions and internal magnetospheric processes. Through continued global international study efforts, like e.g. the International Magnetospheric Study (IMS) and later the International Solar Terrestrial Physics program (ISTP) the 2-dimenional monitoring of geomagnetic “disturbances”, now understood as complex signatures of different current systems within and beyond the upper atmosphere, became a powerful tool to monitor and study the complicated three-dimensional coupling of the magnetosphere to the upper atmosphere and its ultimate relation to certain solar wind drivers of magnetospheric conditions.

 

Geomagnetic observations, both globally and regionally, are today a valuable asset to put the very local measurements of magnetospheric satellites (even if “multi-point”) into its proper context with respect to the dynamics of the magnetosphere. The ultimate goal of such measurements today is not only to identify the energy and activity state of the magnetosphere as such, but also to study the exact location, strength and spatio-temporal development of the most powerful short-lived magnetic disturbances that we know, the so-called magnetospheric substorms and the closely related intensifications of major magnetic storms.

 

The study of the physics of the geo-space environment in response to solar activity and solar wind driving has over the last twenty years matured to make first useful predictions of a large variety of plasma processes in near-Earth space, which have the potential to detrimentally affect human space exploration and human technological infrastructure both on ground and in space. The fast-growing research and operational field of Space Weather has stimulated new active research (including advanced model efforts) to get to the bottom of some of the most effective geo-space plasma phenomena, and to understand the variability of ionospheric currents, and their connection to the outer magnetosphere. This is at present one of the most intriguing scientific problems in the field of Space Weather. Potentially any conducting infrastructure on the ground can be detrimentally or catastrophically affected by fast changes in the magnetic field (dB/dt) via geomagnetically induced currents (GICs). In parallel, the involved ionospheric current systems can cause further secondary impacts on space-borne communication and navigations systems via ionospheric plasma instabilities and atmospheric drag effects on satellite orbits.

 

In my presentation I will give a short background to the historical progress of space science with the help of magnetometer data, and then highlight a selection of recent research topics, where global and regional magnetometer networks (together with a multitude of dedicated space missions) represent a very important part of the systematic and coordinated study of the near-Earth plasma environment, the coupled solar wind - magnetosphere - ionosphere – atmosphere “System of Systems”.

How to cite: Opgenoorth, H.: From Geomagnetism and Space Science to Space Weather, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8054, https://doi.org/10.5194/egusphere-egu23-8054, 2023.

EGU23-8132 | ECS | Orals | ST2.1 | Highlight

Solar Wind Impact on ENAs from Earth’s Subsolar Magnetosheath 

Michael J. Starkey, Maher A. Dayeh, Stephen A. Fuselier, Steven M. Petrinec, David J. McComas, Keiichi Ogasawara, Jamey R. Szalay, Nathan A. Schwadron, and Justyna M. Sokół

The solar wind is heated and decelerated by Earth’s bow shock, resulting in a hot and dense population of magnetosheath ions. This increases the production of energetic neutral atoms (ENAs) in this region, which enables the global imaging of Earth’s magnetosheath using ENA imagers onboard the IBEX spacecraft. Furthermore, since these ENAs are unaffected by electromagnetic forces, they carry information about the inherent properties of the progenitor plasma.       
In this work, ENA fluxes from the subsolar magnetosheath, observed by the IBEX spacecraft, are compared to solar wind (SW) conditions. These comparisons reveal that the flux of ENAs is strongly influenced by the SW density, speed, and temperature. Furthermore, evidence of the specularly reflected proton population in the magnetosheath is observed by comparing ENA spectra for different interplanetary magnetic field configurations. This work provides observational constraints to modeling and theoretical work on ENAs from Earth's subsolar magnetosheath and shows that ENAs from Earth's magnetosheath are reflective of their parent ion populations in the magnetosheath.

How to cite: Starkey, M. J., Dayeh, M. A., Fuselier, S. A., Petrinec, S. M., McComas, D. J., Ogasawara, K., Szalay, J. R., Schwadron, N. A., and Sokół, J. M.: Solar Wind Impact on ENAs from Earth’s Subsolar Magnetosheath, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8132, https://doi.org/10.5194/egusphere-egu23-8132, 2023.

The Earth’s plasmasphere dominates the mass content of the inner magnetosphere. During extended periods of relatively quiet geomagnetic conditions the outer plasmasphere can become diffuse, with a gradual fall-off of plasma density. During increasing magnetospheric activity, however, the plasmasphere is eroded and plumes, forming at the plasmapause and released outwards, constitute a well-established mode for plasmaspheric material release to the Earth’s magnetosphere. These plumes are associated to active periods and the related electric field change. In 1992, Lemaire and Shunk proposed the existence of an additional mode for plasmaspheric material release to the Earth’s magnetosphere: a plasmaspheric wind, steadily transporting cold plasmaspheric plasma outwards across the geomagnetic field lines, even during prolonged periods of quiet geomagnetic conditions. This has been proposed on a theoretical basis. The Cluster spacecraft, that cross the plasmasphere from south to north during their perigee passes, provided for the first time an experimental confirmation of the plasmaspheric wind. This is based on the analysis of ion measurements acquired by the CIS experiment onboard these spacecraft, which allows also to study the plasmaspheric dynamics under various geomagnetic activity conditions. The plasmaspheric wind has been systematically detected in the outer plasmasphere during quiet and moderately active periods, and provides a contribution to the magnetospheric plasma populations outside the Earth’s plasmasphere.

During the early terrestrial evolution (around 2 to 4 billion years ago), when the Earth’s rotation period around its axis was much shorter, the imbalance between gravitational, centrifugal and pressure gradient forces, giving rise to the plasmaspheric wind, should generate much stronger outflows. The plasmapheric wind should then have played an important role in the early evolution of the terrestrial atmosphere, through enhanced atmospheric escape, including the escape of heavy elements (C+, N+, O+). 

 

 

How to cite: Dandouras, I.: Plasmaspheric wind in the Earth’s magnetosphere: contribution to the early evolution of the terrestrial atmosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8322, https://doi.org/10.5194/egusphere-egu23-8322, 2023.

EGU23-8390 | ECS | Posters on site | ST2.1

Ion heat flux associated with the Kelvin-Helmholtz instability in a non-uniform plasma: Numerical hybrid-Vlasov results 

Vertti Tarvus, Lucile Turc, Hongyang Zhou, Giulia Cozzani, Urs Ganse, Yann Pfau-Kempf, Markku Alho, Markus Battarbee, Maxime Dubart, Harriet George, Konstantinos Horaites, Jonas Suni, Fasil Tesema, Ivan Zaitsev, and Minna Palmroth

The presence of a velocity shear layer in a plasma can lead to the development of the Kelvin-Helmholtz instability (KHI). KHI is characterised by the growth of waves that roll up to form non-linear vortices. An example of such velocity shear layer is found at either flank of Earth's magnetopause, where KHI acts a driver of mass and energy transfer from the solar wind into the magnetosphere. Within the rolled-up vortices, kinetic length scales may be attained, allowing vortex-induced magnetic reconnection and kinetic-scale diffusion to operate. In the present study, we have considered the realistic case of a density/temperature jump across the magnetopause and modelled the development of the KHI using a local hybrid-Vlasov simulation with the Vlasiator code. For a case with a northward directed magnetic field, we find that an enhanced ion heat flux arises at vortex boundaries whose thickness approaches the ion gyroscale. Furthermore, the direction of the heat flux vector closely follows the direction of the vortex boundary tangent vector. As such, this signature could provide observational evidence of ion diffusion occurring within KHI, and also information on vortex boundary geometry with single spacecraft data. To validate our results, we compare our simulation run with data from the Magnetospheric Multiscale Mission.

How to cite: Tarvus, V., Turc, L., Zhou, H., Cozzani, G., Ganse, U., Pfau-Kempf, Y., Alho, M., Battarbee, M., Dubart, M., George, H., Horaites, K., Suni, J., Tesema, F., Zaitsev, I., and Palmroth, M.: Ion heat flux associated with the Kelvin-Helmholtz instability in a non-uniform plasma: Numerical hybrid-Vlasov results, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8390, https://doi.org/10.5194/egusphere-egu23-8390, 2023.

EGU23-8439 | Posters on site | ST2.1

Wave-particle interactions in the Earth magnetotail during dipolarization 

Liudmyla Kozak, Bohdan Petrenko, Elena Kronberg, Roman Akhmetshyn, and Istvan Ballai

The energy of particles in the Earth's magnetosphere changes significantly when the configuration of the magnetic field lines suddenly changes from stretched to more dipolar (dipolarization). Energy changes can be caused by variation in electric fields,  due to the generation of electrostatic waves, etc. The presence of heavy ions at the heights of the magnetosphere significantly changes the physics of the processes since, in addition to changing the main characteristics of the plasma (temperature, pressure, Alfven velocity thickness of the current/plasma layer), the conditions and rate of development of instabilities (in particular, the Kelvin-Helmholtz instability) and the nature of turbulent processes will change as well.

In this work, the change of ion and electron fluxes is considered and the peculiarities of resonant interaction of charged particles with electromagnetic fluctuations during the dipolarizations are determined.

The data from the Cluster-II mission spacecraft (magnetic field measurements from ferroelectrode magnetometers (FGM) and energetic particle fluxes from RAPID spectrometers) were used for the analysis. The analysis of individual events is carried out, and a statistical consideration of changes in particle fluxes during magnetic field dipolarizations for 2001–2015 is presented.

Among the features of proton fluxes for individual events, an non-correlation between flux changes in different energy channels is recorded (example, the flux at 27 keV is approximately constant, and is peaks in higher energy ranges). Thus, we have a selective non-adiabatic acceleration of a part of a proton spectrum depending on energy. The change of the spectral index for different energy channels and components was studied.

The values of the power of magnetic field oscillations at gyrofrequencies for different ion types obtained by epoch superposition method showed that resonant interactions of ions with low-frequency electromagnetic waves are more significant for "heavier" components. Therefore the ions can effectively be accelerated by the interaction with these waves during the dipolarization.

This work was supported by the grant no. 97742 of the Volkswagen Foundation (VW-Stiftung), the Royal Society International Exchanges Scheme 2021 IES\R1\211177, and BF/30-2021.

How to cite: Kozak, L., Petrenko, B., Kronberg, E., Akhmetshyn, R., and Ballai, I.: Wave-particle interactions in the Earth magnetotail during dipolarization, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8439, https://doi.org/10.5194/egusphere-egu23-8439, 2023.

EGU23-9371 | Posters on site | ST2.1

Asymmetry in the Terrestrial Plasma Sheet Driven by Dayside Dynamics 

Maher A. Dayeh, Michael J. Starkey, Steven M. Petrinec, Stephen A. Fuselier, Justyna M. Sokół, Keiichi Ogasawara, Jamey R. Szalay, David J. McComas, Eric J. Zirnstein, and Nathan A. Schwadron

The Interstellar Boundary Explorer (IBEX) mission continues to provide energetic neutral atom (ENA) observations of the heliosphere and Earth’s magnetosphere from a global perspective and including spatial, temporal, and energy information. Due to its orbit, IBEX routinely observes the magnetosphere from a side-viewing vantage point, with a field-of-view that is nearly perpendicular to the day-night plane. This enables the construction of composite ENA images at different energies (0.5 – 6.0 keV) for convected solar wind conditions, which provides global insights into different magnetospheric plasma regions and processes.

Earth’s plasma sheet plays a crucial role in the global circulation of plasma throughout the magnetosphere. The structure of the plasma sheet is driven by a combination of effects including interplanetary magnetic field (IMF) and solar wind conditions, internal magnetospheric processes, and Earth’s dipole tilt angle.

This work examines the structure of the plasma sheet in the X-Z geocentric ecliptic plane (GSE) using ENA images from IBEX. The thickness and extent of the plasma sheet is compared for conditions of prolonged northward and southward IMF. We report on a North-South asymmetry in the plasma sheet that is related to the IMF orientation and is driven by a combination of dayside magnetic reconnection effects and high dipole tilt. Results provide evidence of dayside reconnection driving plasma sheet dynamics.

How to cite: Dayeh, M. A., Starkey, M. J., Petrinec, S. M., Fuselier, S. A., Sokół, J. M., Ogasawara, K., Szalay, J. R., McComas, D. J., Zirnstein, E. J., and Schwadron, N. A.: Asymmetry in the Terrestrial Plasma Sheet Driven by Dayside Dynamics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9371, https://doi.org/10.5194/egusphere-egu23-9371, 2023.

EGU23-9727 | ECS | Posters on site | ST2.1

Newcomb-Benford Law characterization of solar wind magnetic field and geomagnetic indices 

Artur Benedito Nunes, Jekaterina Gamper, Matthew Friel, Jesper Gjerloev, and Sandra Chapman

A. M. Benedito Nunes (co-first author), J. Gamper (co-first author), M. Friel, J. W. Gjerloev, S.C. Chapman

 

The Newcomb-Benford Law (NBL) prescribes the probability distribution of the first digit of variables under conditions including aggregation. It will not apply where there is strong truncation or a cut-off. We apply it to space weather relevant magnetic field observations and indices for the first time. In upstream solar wind magnetic field OMNI HRO IMF observations we show that the NBL detects the improvement in data quality with the availability of the WIND and later, ACE spacecraft after 1995, in addition to IMP8. The SMR geomagnetic index averages over multiple ground magnetometer time-series and follows the NBL to a consistent high precision across changing solar activity and a ten-fold increase in the number of constituent stations. The AE and SME indices select the extremal signals from a set of stations. AE, which is mostly based on the same stations throughout its record, follows the NBL to a consistent high precision and with weak but statistically significant variation, it follows the NBL less well during relatively strong solar cycle maxima compared to solar minima. Both the number of constituent stations and the station type comprising SME has changed over the SME record. First, in 1996 the number of available stations increased tenfold, but the station type remained homogeneous. The NBL is followed to a consistent high precision through this period, up to 2006. Beyond 2006, new station types are introduced into the composition of SME and this can be seen in an approximately factor of two drop in the precision with which the NBL is followed. Subsequently, the SME record follows the NBL to varying precision which tracks the inclusion and omission of different types of magnetometer in the record. As the use of composite indices becomes more widespread across the geosciences, the NBL may therefore provide a generic 'data flag' to indicate when the constituent raw data, calibration or sampling method has changed.

How to cite: Benedito Nunes, A., Gamper, J., Friel, M., Gjerloev, J., and Chapman, S.: Newcomb-Benford Law characterization of solar wind magnetic field and geomagnetic indices, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9727, https://doi.org/10.5194/egusphere-egu23-9727, 2023.

EGU23-11179 | Posters on site | ST2.1

Cluster and MMS simultaneous observations of the Earth’s magnetosheath region in 2017-2021 

Costel Munteanu, Eliza Teodorescu, and Marius Echim

We search for ESA’s Cluster and NASA’s MMS missions’ simultaneous observations of the Earth’s magnetosheath (MSH) region. Visual inspection of Cluster quicklook plots is used to determine Cluster-MSH crossings. Next, MMS quicklook plots are inspected, and the MMS-MSH crossings which overlap in time with the Cluster-MSH intervals from step 1, are catalogued. We find 117 simultaneous crossings in 2017-2021. Our overall goal is to investigate the correlation between the properties of the magnetosheath and the bow shock (BS) characteristics. Thus, for each one of the MSH intervals in our catalogue, we determine the BS characteristics. The Earth’s bow shock can be classified as either quasi-parallel or quasi-perpendicular, depending on the angle between the interplanetary magnetic field (IMF) and bow shock normal direction. We use OMNI data to determine the IMF direction, and we estimate the BS normal direction using two approaches: (1) from magnetic field measurements using minimum variance analysis and (2) from a bow shock model using solar wind data as input. We will present our catalogue of simultaneous Cluster-MMS magnetosheath crossings, and also our estimates for the BS type associated with each crossing.

How to cite: Munteanu, C., Teodorescu, E., and Echim, M.: Cluster and MMS simultaneous observations of the Earth’s magnetosheath region in 2017-2021, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11179, https://doi.org/10.5194/egusphere-egu23-11179, 2023.

EGU23-11764 | ECS | Posters virtual | ST2.1

Uncertainty Quantification in Global Simulations: Solar Wind Propagation Effects 

Qusai Al Shidi, Tuija Pulkkinen, and Daniel Welling

We created a database of over 100 simulations of geomagnetic storms from the time interval from 2010 to 2019, using the Geospace configuration of the Space Weather Modeling Framework. With this data set, we explore and quantify the errors that arise from the uncertainties of the input solar wind data set that comes from the OMNI database, using global magnetic indices such as SYM-H, AL and Cross Polar Cap Potential as measures of the model output that can be directly compared with observations. Our results show that the method of propagation of the solar wind data from the spacecraft location near L1 to the bow shock nose causes errors that are much smaller than those arising from the limitations in modeling the solar wind – magnetosphere – ionosphere coupling processes during strong solar wind driving. We devise a method to quantify these uncertainties, which may become useful in understanding the output of global simulations. These results will be useful as well for research investigations of magnetospheric processes as well as for forecasting space weather.

How to cite: Al Shidi, Q., Pulkkinen, T., and Welling, D.: Uncertainty Quantification in Global Simulations: Solar Wind Propagation Effects, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11764, https://doi.org/10.5194/egusphere-egu23-11764, 2023.

EGU23-12182 | Posters on site | ST2.1

Validating in-situ measurements of ULF Waves in Low Earth Orbit 

Jiwon Choi, Dong-Hun Lee, Kyungguk Min, Kichang Yoon, and Jong Uk Park

Ultra-low frequency (ULF) waves in the Earth’s magnetosphere are commonly observed in space as well as on the ground stations. Located between the magnetosphere and the earth’s surface, the lower-thermosphere-ionosphere region is expected to be abundant in ULF waves. Transverse Alfven waves are of interest since they have one-dimensional nature along the magnetic field lines with radial variation in their characteristic frequencies. We have conducted three-dimensional magnetohydrodynamic wave simulations to investigate ULF observations by various types of low-Earth orbit (LEO) satellites. Virtual spacecraft are embedded in our model to measure electromagnetic wave signals as they move at different altitudes and latitudes. Our results present that the waveform and frequency of transverse waves change significantly when they are observed in low Earth orbit. Since the majority of LEO satellites lay in polar orbit, they traverse different field lines at relatively high speeds. Thus, fast movement through Alfven speed gradient along the spacecraft trajectory alters the frequency of transverse Alfven waves. It is worth noting that the observed frequency by virtual satellites in low-Earth orbit becomes ~8 times higher than the original frequency. It indicates that frequency distortion from LEO satellite observations can cause serious differences between ground-based and satellite observations. We suggest validating ULF wave observations in low-Earth orbit using a series of spacecraft such as the CubeSat constellation can improve the robustness of electromagnetic field measurements in LEO.

How to cite: Choi, J., Lee, D.-H., Min, K., Yoon, K., and Park, J. U.: Validating in-situ measurements of ULF Waves in Low Earth Orbit, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12182, https://doi.org/10.5194/egusphere-egu23-12182, 2023.

EGU23-12541 | Posters on site | ST2.1

Magnetotail configurations during ballooning-interchange instability signatures 

Evgeny V. Panov, Marina V. Kubyshkina, Victor A. Sergeev, Rumi Nakamura, and Wolfgang Baumjohann

In situ observations revealed both linear and non-linear signatures of the kinetic (electron) ballooning-interchange instability (BICI) operating in the Earth’s magnetotail, which appear to drive auroral beads and pseudo-breakups in the ionosphere. Observation of the magnetotail configurations with inversed gradient of the vertical magnetic field, which is believed to drive the BICI is challenged by sparse spacecraft coverage. We use the adapted modeling based on in situ spacecraft observations, and low-altitude particle observations to extract some information on such magnetotail configurations. We present two in situ events with both linear and non-linear BICI development signatures and compare the magnetotail configurations during the two events using the two methods.

How to cite: Panov, E. V., Kubyshkina, M. V., Sergeev, V. A., Nakamura, R., and Baumjohann, W.: Magnetotail configurations during ballooning-interchange instability signatures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12541, https://doi.org/10.5194/egusphere-egu23-12541, 2023.

EGU23-12580 | Posters on site | ST2.1

Study of kinetic processes based on MMS/Cluster joint measurements in the vicinity of the plasma sheet boundary layer 

Olivier Le Contel, Alessandro Retino, Thomas Chust, Konrad Steinvall, Soboh Alqeeq, Mohammed Baraka, Patrick Canu, Dominique Fontaine, Laurent Mirioni, Iannis Dandouras, Christopher Carr, Sergio Toledo-Redondo, Andrew Fazakerley, Natasha Doss, Patrick Daly, Stefan Kiehas, Rumi Nakamura, Yuri Khotyaintsev, Frederick Wilder, and Narges Ahmadi and the Joint Cluster/MMS team

On 28th of August 2018 at 5:30 UT, MMS and Cluster were located in the magnetotail at about 16 earth radii (RE). They both suddenly crossed plasma interfaces. Located near the post midnight sector, Cluster transitioned from a cold plasma sheet to a hot plasma sheet associated with a quasi-parallel earthward flow 800 km/s whereas MMS, located at 4 RE duskward of Cluster, transitioned from a similar cold plasma sheet to the lobe region via a very short period in a hot plasma sheet associated with a vortex-like signature. At 05:50 UT MMS returned to a hot plasma sheet and also detected a quasi-parallel earthward flow ~ 400 km/s and increased energetic ion and electron fluxes. We use measurements from both missions during this conjunction to describe the possible large scale dynamics of the magnetotail as well as some associated kinetic processes. Energetic particle (>50keV) measurements from the two missions are compared. Furthermore, at ion scales, we investigate the possible role of ion fire-hose instability in the plasma flow reduction. At electron scales, we analyze fast and slow non linear electrostatic waves propagating tailward which are detected in the so called electron boundary layer as well as in the hot plasma sheet. We discuss their possible generation mechanisms and link with the large scale dynamics of the magnetotail.

How to cite: Le Contel, O., Retino, A., Chust, T., Steinvall, K., Alqeeq, S., Baraka, M., Canu, P., Fontaine, D., Mirioni, L., Dandouras, I., Carr, C., Toledo-Redondo, S., Fazakerley, A., Doss, N., Daly, P., Kiehas, S., Nakamura, R., Khotyaintsev, Y., Wilder, F., and Ahmadi, N. and the Joint Cluster/MMS team: Study of kinetic processes based on MMS/Cluster joint measurements in the vicinity of the plasma sheet boundary layer, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12580, https://doi.org/10.5194/egusphere-egu23-12580, 2023.

EGU23-12911 | Orals | ST2.1 | Highlight

Jets downstream of the Earth’s bow shock 

Heli Hietala

The downstream region of a collisionless quasi-parallel shock is structured containing localized bulk flows with high kinetic energy density and dynamic pressure. In 2009, we presented Cluster multi-spacecraft measurements of this type of supermagnetosonic jet as well as of a weak secondary shock within the sheath. These observations allowed us to propose the following generation mechanism for the jets: The local curvature variations inherent to quasi-parallel shocks can create fast, slightly deflected jets accompanied by density variations in the downstream region. If the speed of the jet is super(magneto)sonic in the reference frame of the surrounding flow and/or the magnetopause, a second shock front forms in the sheath.

During the following years, magnetosheath jets have been a continually active research topic. Studies using increasingly large databases of spacecraft observations have gathered the statistics of jet formation conditions and properties. Simulations and case studies have shed light on jet formation mechanisms. Within the magnetosheath, the jet-driven secondary bow waves/shocks have been shown to contribute to particle energization. Investigations of jet impacts on the magnetosphere have revealed a plethora of effects, ranging from surface waves and magnetopause reconnection to diffuse auroral brightenings.

In this talk, we will summarize the progress to date and highlight some still open questions.

How to cite: Hietala, H.: Jets downstream of the Earth’s bow shock, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12911, https://doi.org/10.5194/egusphere-egu23-12911, 2023.

EGU23-13452 | ECS | Posters on site | ST2.1

Global simulation of geospace electrons: eVlasiator in 3D 

Markku Alho, Markus Battarbee, Leo Kotipalo, Maxime Grandin, Yann Pfau-Kempf, Urs Ganse, Giulia Cozzani, Maarja Bussov, Evgenii Gordeev, Konstantinos Horaites, Fasil Tesema Kebede, Konstantinos Papadakis, Jonas Suni, Vertti Tarvus, Lucile Turc, Ivan Zaitsev, Hongyang Zhou, and Minna Palmroth

Models of the geospace plasma environment have been proceeding towards more realistic descriptions of the solar wind—magnetosphere interaction, from gas-dynamic to MHD and hybrid ion-kinetic models such as the state-of-the-art Vlasiator model. Advances in computational capabilities have enabled global simulations of detailed physics, with some inroads to electron physics made with eVlasiator, specifically, in a meridional 2D+3V simulation.

In this work we present preliminary results from eVlasiator, an offshoot of the Vlasiator model, showing results from a global 3D+3V kinetic electron geospace simulation. Previous work in a spatially 2D environment has shown, despite truncation of some electron physics and use of ion-scale spatial resolution, that realistic electron distribution functions are obtainable within the magnetosphere. This work examines the differences between the spatially 2D and the new spatially 3D results, and describe these in relation to MMS observations. Electron precipitation to the upper atmosphere from these velocity distributions is estimated.

How to cite: Alho, M., Battarbee, M., Kotipalo, L., Grandin, M., Pfau-Kempf, Y., Ganse, U., Cozzani, G., Bussov, M., Gordeev, E., Horaites, K., Kebede, F. T., Papadakis, K., Suni, J., Tarvus, V., Turc, L., Zaitsev, I., Zhou, H., and Palmroth, M.: Global simulation of geospace electrons: eVlasiator in 3D, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13452, https://doi.org/10.5194/egusphere-egu23-13452, 2023.

EGU23-13756 | ECS | Posters on site | ST2.1

Kinetic Alfvén waves from hybrid-Vlasov simulations 

Hongyang Zhou, Lucile Turc, Guilia Cozzani, Ivan Zaitsev, Yann Pfau-Kempf, Konstantinos Horaites, Fasil Kebede, Markus Battarbee, Markku Alho, Maxime Grandin, Evgenii Gordeev, Vertti Tarvus, Maxime Dubart, Jonas Suni, Konstantinos Papadakis, Urs Ganse, and Minna Palmroth

Kinetic Alfvén wave (KAW) is the kinetic extension of shear Alfvén wave (SAW) where the perpendicular wavelength with respect to the magnetic field becomes comparable to the ion scale. It has been suggested theoretically that mode conversion from incident compressional waves to KAWs at the magnetopause leads to the plasma transport. Existence of KAWs has been identified from in-situ observations and shown to be closely related to the Hall field from magnetic reconnection. In this study, we investigate the properties of KAWs using the hybrid-Vlasov model Vlasiator. Local runs of tangential discontinuities with parameters relevant to Earth’s magnetopause are performed to look at the mode conversion from fast waves to Alfvén waves. Signatures of KAWs are identified from both local and global simulations, which provide insights into the nonlinear plasma transport process in the magnetosphere.

How to cite: Zhou, H., Turc, L., Cozzani, G., Zaitsev, I., Pfau-Kempf, Y., Horaites, K., Kebede, F., Battarbee, M., Alho, M., Grandin, M., Gordeev, E., Tarvus, V., Dubart, M., Suni, J., Papadakis, K., Ganse, U., and Palmroth, M.: Kinetic Alfvén waves from hybrid-Vlasov simulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13756, https://doi.org/10.5194/egusphere-egu23-13756, 2023.

EGU23-14113 | ECS | Orals | ST2.1 | Highlight

Analysis of IMF penetration into Mercury’s Magnetosphere 

Kristin Pump, Daniel Heyner, Adam Masters, Sophia Zomerdijk-Russell, and Ferdinand Plaschke

Mercury is the smallest an innermost planet of our solar system and has a dipole-dominated internal magnetic field that is relatively weak, very axisymmetric and significantly offset towards north. Through the interaction with the solar wind, this field leads to a magnetosphere. Compared to the magnetosphere of Earth, Mercury’s magnetosphere is smaller and more dynamic.

A semi-empirical magnetospheric model can capture the large-scale magnetospheric structures. Using the residuals between in-situ data and the model prediction we further seek to improve our understanding of the Hermean magnetosphere.
To first order the magnetopause completely separates the magnetosphere from the magnetosheath and thus no magnetic field may penetrate this boundary. In reality, the magnetosheath field may diffuse across the very thin boundary within a finite time. 

Here, we investigate this penetration and compare the different interplanetary field (IMF) components by their ability to enter into Mercury’s Magnetosphere. For this, we use in-situ MESSENGER magnetic field data to estimate the IMF for the time frame with the probe located inside the magnetosphere. The amount of penetration is found by least-square fitting to magnetospheric model results.
First statistical results indicate that the penetration is stronger under southward IMF conditions.

How to cite: Pump, K., Heyner, D., Masters, A., Zomerdijk-Russell, S., and Plaschke, F.: Analysis of IMF penetration into Mercury’s Magnetosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14113, https://doi.org/10.5194/egusphere-egu23-14113, 2023.

EGU23-14602 | ECS | Orals | ST2.1

Application of the wave telescope to Vlasiator simulations using multi-scale spacecraft configurations 

Leonard Schulz, Ferdinand Plaschke, Karl-Heinz Glassmeier, Uwe Motschmann, Yasuhito Narita, Minna Palmroth, Owen Roberts, and Lucile Turc

The wave telescope is a multi-spacecraft method that uses multi-point magnetic field data to estimate a spectrum in k-space, allowing for the detection of waves as well as turbulence. So far, the wave telescope has been applied to the Cluster and MMS four-spacecraft missions around Earth. In the future, it can be used for multi-scale plasma missions incorporating larger numbers of spacecraft. Such are the accepted Helioswarm mission as well as the proposed Plasma Observatory. Due to the more complicated nature of the wave telescope analysis of multi-scale spacecraft configurations, there is a need to study such systems beforehand using as-realistic-as-possible artificial data. Such an artificial 2D or 3D dataset can be provided by Vlasiator, a Hybrid-Vlasov global magnetospheric simulation treating electrons as a fluid and protons being described by distribution functions. We apply the wave telescope to spacecraft configurations both different in number and position and determine the quality of detection of foreshock plasma waves simulated by Vlasiator.

How to cite: Schulz, L., Plaschke, F., Glassmeier, K.-H., Motschmann, U., Narita, Y., Palmroth, M., Roberts, O., and Turc, L.: Application of the wave telescope to Vlasiator simulations using multi-scale spacecraft configurations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14602, https://doi.org/10.5194/egusphere-egu23-14602, 2023.

EGU23-16752 | ECS | Orals | ST2.1

Dawn-Dusk Asymmetry of the Kelvin-Helmholtz Waves at Earth's Magnetopause: One Solar cycle data 

Shiva Kavosi and Katariina Nykyri

Kelvin–Helmholtz instability (KHI) plays a crucial role in solar wind plasma entry into the magnetosphere during the period of northward interplanetary magnetic field (IMF). Several studies have revealed the existence of dawn-dusk asymmetry of KHI along the Earth's magnetopause. However, the causes for such asymmetry are still speculative. Here we survey 11 years of in situ data from the NASA THEMIS (Time History of Events and Macro scale Interactions during Substorms) and MMS (Magnetospheric Multiscale) missions. We found that Kelvin–Helmholtz waves (KHWs) occurrence rates and locations exhibit a semiannual variation; the rate maximizes at the equinoxes and minimizes at the solstice. The rate varies for different IMF By polarities; it is maximum around the fall equinox for negative IMF By, while it is maximum around the spring equinox for positive IMF By. It is shown that the dawn-dusk and north-south asymmetry can be attributed to both the dipole tilt angle and the polarity of Interplanetary magnetic fields (IMF) By; KHI in the northern hemisphere favors the dawn sector for positive dipole tilt and the dusk sector for negative dipole tilt and vice versa in the southern hemisphere. This phase of dawn-dusk asymmetry is dependent on the IMF By polarities.

How to cite: Kavosi, S. and Nykyri, K.: Dawn-Dusk Asymmetry of the Kelvin-Helmholtz Waves at Earth's Magnetopause: One Solar cycle data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16752, https://doi.org/10.5194/egusphere-egu23-16752, 2023.

EGU23-16951 | ECS | Orals | ST2.1 | Highlight

Intermittent magnetic reconnection in the magnetotail 

Cecilia Norgren, Norah Kwagala, Michael Hesse, Tai Phan, and Yuri Khotyaintsev

We report an event of intermittent reconnection from the terrestrial magnetotail observed by the Magnetospheric MultiScale mission. First, magnetic reconnection is active, inferred from a field-aligned off-equatorial plasma jet. Over 40 seconds, this jet is replaced by a quiet time interval with dusk-ward diamagnetic ion flow carried by a hot population that persists for about two minutes. During this interval, we observe signs of current sheet thickening followed by thinning. The change in the dawn-dusk current associated with the inferred thickening is provided by changes in the electron flux, and we argue this is a result of momentum conservation. Thereafter, we observe an equatorial jet of hot plasma that gradually builds up before the spacecraft encounter a dipolarization front about 20 seconds later. This first dipolarization front is associated with a transition from a hot pre-existing plasma sheet, to colder plasma of lobe origin. This event showcases behavior during intermittent magnetic reconnection and may help us understand the spatiotemporal evolution of reconnecting regions.

How to cite: Norgren, C., Kwagala, N., Hesse, M., Phan, T., and Khotyaintsev, Y.: Intermittent magnetic reconnection in the magnetotail, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16951, https://doi.org/10.5194/egusphere-egu23-16951, 2023.

EGU23-550 | ECS | Orals | ST2.2

Identifying the zoo of waves in Magnetosheathjets using MMS burst data 

Eva Krämer, Maria Hamrin, Herbert Gunell, Tomas Karlsson, Konrad Steinvall, Oleksandr Goncharov, and Mats André

The magnetosheath is a region downstream of the bow shock filled with turbulent, decelerated solar wind plasma which is flowing earthwards. This solar wind flow sometimes shows signatures of localized structures with enhanced dynamic pressure, so called magnetosheath jets. These jets are often  associated with low angles between the bow shock normal and the interplanetary magnetic field (IMF) direction, the so called quasi-parallel bow shock. Less often they are also found behind the quasi-perpendicular bow shock.


As jets propagate through the magnetosheath, they interact with the surrounding plasma. Studying waves inside, and in the vicinity of, jets is a step towards understanding the interaction of jets with the surrounding plasma. So far whistler waves, electrostatic waves, waves in the lower hybrid frequency range as well as low frequency waves have been reported. However, the sources of these waves are unknown. In addition, further types of waves may be associated with the jets.


We conduct a study on waves in magnetosheath jets using burst mode data of the Magnetospheric Multiscale (MMS) mission. The magnetic and electric field data are provided with a sampling rate of 8 kHz, while previous studies used data sets with much lower sampling rates. The high time resolution allows us to study different waves over a large frequency range and investigate properties of these waves. In addition, we discuss possible generation mechanisms.

How to cite: Krämer, E., Hamrin, M., Gunell, H., Karlsson, T., Steinvall, K., Goncharov, O., and André, M.: Identifying the zoo of waves in Magnetosheathjets using MMS burst data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-550, https://doi.org/10.5194/egusphere-egu23-550, 2023.

EGU23-929 | ECS | Posters on site | ST2.2

Velocity distribution functions and non‐Maxwellianity of magnetosheath jets using MMS 

Savvas Raptis, Tomas Karlsson, Andris Vaivads, Martin Lindberg, and Henriette Trollvik

The interaction between the solar wind and Earth’s magnetic field results in the formation of a supercritical bow shock. Downstream of this shock wave, the magnetosheath region emerges, in which high-speed plasma flows can be formed.  These jets have been connected to several shock and foreshock properties. Moreover, due to their unique properties (i.e., higher density and velocity compared to the ambient flow), they can cause a variety of different phenomena, including magnetopause reconnection, excitation of ULF waves and electron acceleration.

In this work, we use Magnetosphere Multiscale (MMS) mission to demonstrate jets’ complex structure by investigating their velocity distribution functions. Specifically, we focus on how their VDFs change over time and on whether they exhibit non-Maxwellian properties. By comparing with the VDFs taken from the background magnetosheath, we show that full particle plasma moments provide an inadequate description of jet plasma properties. Furthermore, we present different metrics to quantify the non-Maxwellian features exhibited by jet observations. Finally, we discuss how the observed kinetic properties of jets may provide insight into jets generation, wave excitation and evolution.

How to cite: Raptis, S., Karlsson, T., Vaivads, A., Lindberg, M., and Trollvik, H.: Velocity distribution functions and non‐Maxwellianity of magnetosheath jets using MMS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-929, https://doi.org/10.5194/egusphere-egu23-929, 2023.

EGU23-1222 | ECS | Posters on site | ST2.2

Study of the Local Bow Shock Environment during Magnetosheath Jet Formation: Vlasiator Results 

Jonas Suni, Minna Palmroth, Markus Battarbee, Lucile Turc, Markku Alho, Giulia Cozzani, Maxime Dubart, Urs Ganse, Harriet George, Evgeny Gordeev, Maxime Grandin, Konstantinos Horaites, Konstantinos Papadakis, Yann Pfau-Kempf, Vertti Tarvus, Fasil Tesema, Ivan Zaitsev, and Hongyang Zhou

Magnetosheath jets are a class of phenomena that are usually defined as structures of enhanced dynamic pressure in the magnetosheath. The origins of some jets have been traced back to steepening ULF waves in the foreshock, but other formation mechanisms have also been described. In this study we use four 2D simulation runs of the global magnetospheric hybrid-Vlasov simulation Vlasiator to investigate the formation of magnetosheath jets at the bow shock. We use 2D views of the simulation and virtual spacecraft to investigate the plasma and magnetic field properties around and at the times and locations of jet formation. We find that of the 796 jets analysed this way, 91% appear to form in association with foreshock structures of enhanced dynamic pressure impacting the bow shock. These jets mainly form downstream of the ULF foreshock, while the remaining 9% are generally found near the ULF foreshock edges toward the flanks and have different properties from the foreshock structure-associated jets.

How to cite: Suni, J., Palmroth, M., Battarbee, M., Turc, L., Alho, M., Cozzani, G., Dubart, M., Ganse, U., George, H., Gordeev, E., Grandin, M., Horaites, K., Papadakis, K., Pfau-Kempf, Y., Tarvus, V., Tesema, F., Zaitsev, I., and Zhou, H.: Study of the Local Bow Shock Environment during Magnetosheath Jet Formation: Vlasiator Results, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1222, https://doi.org/10.5194/egusphere-egu23-1222, 2023.

EGU23-1305 | Posters on site | ST2.2

Mirror mode-like structures around unmagnetised planets: 1. Mars as observed by the MAVEN spacecraft 

Cyril Simon Wedlund, Martin Volwerk, Christian Mazelle, Sebastián Rojas Mata, Gabriella Stenberg Wieser, Yoshifumi Futaana, Jasper Halekas, Diana Rojas-Castillo, César Bertucci, and Jared Espley

Temperature anisotropy-driven instabilities such as the mirror mode and ion cyclotron instabilities are responsible for the generation of waves in the turbulent magnetosheath of planets. We present two statistical studies of mirror mode-like structures in the magnetosheaths of (mostly) unmagnetised planets such as Mars and Venus, characterised in the same way and with the same tools with the help of on-board magnetometers. In this presentation, we discuss observations by the MAVEN spacecraft. As in our companion Venus study (see poster by Volwerk et al. in the same session), we use magnetic field-only measurements to constrain and identify these quasi-linear compressive structures and discuss ways to mitigate false positive detections based on one instrument only. After calculating the residence time of the spacecraft in the Martian magnetoenvironment, we show two-dimensional statistical maps of mirror mode-like occurrence rates with respect to EUV solar flux levels, Mars Year, and atmospheric seasons. We find detection probabilities of about 1% at most, with two main regions of occurrence, one behind the collisionless shock, the other close to the induced magnetospheric boundary, with the clearest modulation of the probability due to EUV solar flux conditions. Finally, we qualitatively compare our results with past studies at Mars.

How to cite: Simon Wedlund, C., Volwerk, M., Mazelle, C., Rojas Mata, S., Stenberg Wieser, G., Futaana, Y., Halekas, J., Rojas-Castillo, D., Bertucci, C., and Espley, J.: Mirror mode-like structures around unmagnetised planets: 1. Mars as observed by the MAVEN spacecraft, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1305, https://doi.org/10.5194/egusphere-egu23-1305, 2023.

EGU23-1532 | Posters on site | ST2.2

Mirror mode-like structures around unmagnetised planets: 2. Venus as observed by the Venus Express spacecraft 

Martin Volwerk, Cyril Simon Wedlund, David Mautner, Sebastian Rojas Mata, Gabriella Stenberg Wieser, Yoshifumi Futaana, Markus Fraenz, Christian Mazelle, Diana Rojas-Castillo, Cesar Bertucci, and Magda Delva

Temperature anisotropy-driven instabilities such as the mirror mode and ion cyclotron instabilities are responsible for the generation of waves in the turbulent magnetosheath of planets. We present here a statistical study of mirror mode-like structures in the magnetosheath of Venus as observed by the Venus Express spacecraft. As in our Mars study (see poster by Simon Wedlund et al. in the same session), we use magnetic field-only measurements to constrain and identify these quasi-linear compressive structures and discuss ways to mitigate false positive detections based on one instrument only. After calculating the residence time of the spacecraft in the Venusian magnetoenvironment, we show two-dimensional statistical maps of mirror mode-like occurrence rates with respect to EUV solar flux levels, and type of bow shock (quasi-perpendicular vs quasi-parallel). We find detection probabilities of about 10% at most, with two main regions of occurrence, one behind the collisionless shock, the other close to the induced magnetospheric boundary, with the small modulation of the probability due to EUV solar flux conditions.

How to cite: Volwerk, M., Simon Wedlund, C., Mautner, D., Rojas Mata, S., Stenberg Wieser, G., Futaana, Y., Fraenz, M., Mazelle, C., Rojas-Castillo, D., Bertucci, C., and Delva, M.: Mirror mode-like structures around unmagnetised planets: 2. Venus as observed by the Venus Express spacecraft, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1532, https://doi.org/10.5194/egusphere-egu23-1532, 2023.

EGU23-2438 | ECS | Orals | ST2.2

The bow shock and magnetosheath responses to density depletion structures 

Xi Lu, Hui Zhang, Antonius Otto, Terry Liu, and Xingran Chen

Hot flow anomalies (HFAs) are typical and important foreshock transients characterized by large flow deflection and plasma heating. HFAs can deform the Earth’s bow shock by dynamic pressure perturbation resulting in disturbance in the magnetosphere and ionosphere. Traditionally, HFAs are believed to be associated with discontinuities. But recently, HFA-like structures were simulated by an magnetohydrodynamics (MHD) model without the discontinuity prerequisite. In this study, we give three HFA examples to verify this MHD formation mechanism. For the first event, we use multi-points observation from the THEMIS mission to track the formation of the HFA accompanying with a density depletion upstream. For the other two events, we compare observations from the MMS mission and the ARTEMIS mission with the MHD simulation results using density depleted solar wind flux tubes to investigate the physical process of HFA formation. The comparison of simulation and observation shows general agreement particularly in the presence of a core with strong heating and velocity deflection, and two compression regions (shocks) with clear maxima in the ram pressure with a strongly inclined normal boundary at the leading edge and moderately inclined at the trailing edge. Agreement was better when the MHD simulations used a transient change to quasi-parallel solar wind magnetic field during the events. Result suggests that ram pressure may be an excellent diagnostic for HFAs both in the solar wind and in the magnetosheath.

How to cite: Lu, X., Zhang, H., Otto, A., Liu, T., and Chen, X.: The bow shock and magnetosheath responses to density depletion structures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2438, https://doi.org/10.5194/egusphere-egu23-2438, 2023.

EGU23-2702 | Posters on site | ST2.2

MESSENGER observations of short, large-amplitude magnetic structures (SLAMS) in the Mercury foreshock 

Tomas Karlsson and Ferdinand Plaschke

We have investigated approximately four years of MESSENGER data to identify short, large-amplitude magnetic structures (SLAMS) in the Mercury foreshock. Defining SLAMS as well-defined structures with a magnetic field strength of at least a factor of 3 higher than the background magnetic field, when MESSENGER is located in the solar wind, we find 435 SLAMS. The SLAMS are found either in regions of a general ultra-low frequency (ULF) wave field, at the boundary of such a ULF wave field, or isolated from the wave field. We invetigate several properties of the SLAMS, such as temporal scale size, amplitude, and polarization. We find that SLAMS are mostly found during periods of low interplanetary magnetic field strength, indicating that they are more common for higher solar wind Alfvénic Mach number (MA). We use the Tao solar wind model to estimate solar wind parameters to verify that MA is indeed larger during SLAMS observations than otherwise. Finally, we also investigate how SLAMS observations are related to foreshock geometry.

How to cite: Karlsson, T. and Plaschke, F.: MESSENGER observations of short, large-amplitude magnetic structures (SLAMS) in the Mercury foreshock, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2702, https://doi.org/10.5194/egusphere-egu23-2702, 2023.

EGU23-2963 | ECS | Posters virtual | ST2.2

Electron acceleration by intense whistler-mode waves at foreshock transients 

Xiaofei Shi, Anton Artemyev, Vassilis Angelopoulos, Terry Liu, and Xiao-Jia Zhang

The shock wave is a primary interface for plasma heating and charged particle acceleration. In collisionless solar wind plasma, such acceleration is attributed to the wave-particle resonant interactions. This letter focuses on electron acceleration by one of the most widespread high-frequency electromagnetic wave emissions, whistler-mode waves. Using spacecraft observations of the Earth's foreshock transient, we demonstrate that intense whistler-mode waves may resonate nonlinearly with $\sim 10-100$eV solar wind electrons and accelerate them to $\sim 100-500$eV. Accelerated electron population has a butterfly pitch-angle distribution, in agreement with theoretical predictions. The presented evidence of the efficiency of nonlinear resonant acceleration suggests that this mechanism may play an important role in solar wind electron injection into the shock-drift acceleration.

How to cite: Shi, X., Artemyev, A., Angelopoulos, V., Liu, T., and Zhang, X.-J.: Electron acceleration by intense whistler-mode waves at foreshock transients, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2963, https://doi.org/10.5194/egusphere-egu23-2963, 2023.

EGU23-3155 | ECS | Posters on site | ST2.2

Jet-like structures in different regions of the magnetosheath 

Oleksandr Goncharov, Jana Šafránková, Zdeněk Němeček, and Niki Xirogiannopoulou

Plasma structures with the enhanced dynamic pressure, density or speed are often observed in the Earth’s magnetosheath. These structures, known as jets and fast plasmoids, can be registered in the magnetosheath, downstream both the quasi-perpendicular and quasi-parallel bow shocks (BS). Using measurements by the Magnetospheric Multiscale (MMS) spacecraft, Goncharov et al. (2020) showed similarities in the plasma properties of the jets and fast plasmoids. However, they pointed out that the different magnetic fields inside the structures suggest that the formation mechanisms are different. Hybrid simulations by Preisser et al. (2020) have shown differences in the mechanisms of jet and embedded plasmoid formation. On the other hand, structures registered close to the BS/magnetopause or in the sub-solar/flank magnetosheath are not fully the same. Based on our comparative analysis, we discuss features of jet-like structures, their properties, occurrence, evolution, and relation to the magnetosheath parameters.

How to cite: Goncharov, O., Šafránková, J., Němeček, Z., and Xirogiannopoulou, N.: Jet-like structures in different regions of the magnetosheath, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3155, https://doi.org/10.5194/egusphere-egu23-3155, 2023.

EGU23-3199 | ECS | Posters on site | ST2.2

Characteristics of foreshock subsolar compressive structures and their connection to magnetosheath jet-like phenomena 

Niki Xirogiannopoulou, Oleksandr Goncharov, Jana Šafránková, and Zdeněk Němeček

The turbulent foreshock region upstream of the quasi- parallel bow shock is dominated by waves and reflected particles that interact with each other and create a large number of different foreshock phenomena. The plasma structures with the enhanced magnetic field (Short Large Amplitude Magnetic Structures, SLAMS), and density spikes, named plasmoids, are frequently observed. They are one of the suggested sources of transient flux enhancements (TFE) or jets in the magnetosheath. Using measurements of the Magnetospheric Multiscale Spacecraft (MMS) and OMNI solar wind database between 2015 and 2018 years, we have found that there is a category of events exhibiting both magnetic field and density enhancements simultaneously and we introduce the term “mixed structure” for them. Consequently, we divided our set of observations into three groups and present a comparative statistical analysis in the subsolar foreshock. Based on our results and previous research, we discuss their properties, possible origin, occurrence rate under different upstream conditions and their relation to the jets and plasmoids in the magnetosheath. We suggest that plasmoids and SLAMS are different phenomena created in the foreshock under different upstream conditions and that the enhanced density, rather than magnetic field magnitude, is principal for creation of magnetosheath jets.

How to cite: Xirogiannopoulou, N., Goncharov, O., Šafránková, J., and Němeček, Z.: Characteristics of foreshock subsolar compressive structures and their connection to magnetosheath jet-like phenomena, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3199, https://doi.org/10.5194/egusphere-egu23-3199, 2023.

EGU23-3758 | ECS | Posters on site | ST2.2

Kinetic simulation of proton mirror instability 

Chun-Kai Chang and Lin-Ni Hau

Mirror mode waves with anticorrelated density and magnetic field perturbations have been widely observed in the planetary magnetosheaths and solar wind. In this study we examine the time evolution of proton mirror instability based on the hybrid particle simulation with the focus being on the thermodynamics of mirror waves. A set of double-polytropic (DP) laws are adopted to infer the corresponding thermodynamic conditions characterized by the polytropic exponents, γand γ. It is shown that the γ⊥, values at the saturation stages are in the ranges of γ⊥ = 0.64±0.21 and γ = 1.07±0.12 which are consistent with the observations and linear kinetic theory (Hau et al. 2021). The saturated plasma β are well fitted by the modified DP MHD mirror condition of γβ = β2/(2+γβ) with γ≈ 0.8, γ ≈ 1.3 which may be used as a new mirror criterion for the mirror waves observed in the solar system.

How to cite: Chang, C.-K. and Hau, L.-N.: Kinetic simulation of proton mirror instability, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3758, https://doi.org/10.5194/egusphere-egu23-3758, 2023.

In the foreshock region of planetary and terrestrial bow shocks, interaction of reflected solar wind ions with the incident solar wind and the interplanetary magnetic field gives rise to a variety of transient plasma structures and instabilities, and the ion dynamics and ion kinetic scale processes drive the foreshock environment. In this comparative study, we consider specific examples of transient foreshock structures upstream of Mars and Earth and contrast differences between theri formation process, contributing ion populations, and source region of ion populations. Due to the smaller size of Mars and its bow shock compared to Earth and with respect to upstream ion convective gyroradius, reflected ions with hybrid trajectories that straddle between the quasi-perpendicular and quasi-parallel bow shocks can contribute to formation of foreshock transients. The size of transient foreshock structures upstream of Mars differs compared to Earth, which influences their propagation and impact through the magnetosheath and lower plasma boundaries.

How to cite: Madanian, H.: Formation of Transient Foreshock Structures Upstream of Mars and Earth: A Comparative Study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4004, https://doi.org/10.5194/egusphere-egu23-4004, 2023.

EGU23-4366 | Posters on site | ST2.2

On the scale sizes of magnetic holes 

Ferdinand Plaschke, Martin Volwerk, Tomas Karlsson, Charlotte Götz, Daniel Heyner, Heli Hietala, Johannes Z. D. Mieth, Daniel Schmid, Cyril Simon-Wedlund, and Zoltan Vörös

Magnetic holes are significant depressions of the interplanetary magnetic field (IMF) that can be found embedded in the solar wind everywhere within the heliosphere. They resemble mirror mode magnetic structures that form as a response to excess perpendicular temperatures. Magnetic holes situated at IMF discontinuities (current sheets) may also be the result of reconnection. Magnetic holes occur more often under fast solar wind conditions, and their scale sizes are known to be on the order of thousands to tens of thousands of km, determined essentially from temporal width and plasma velocity observations. So far, the scale sizes have only been estimated for the directions parallel to the respective solar wind plasma flows. In this study, we attempt to calculate the first distributions of the scale sizes for the orthogonal, flow-perpendicular directions. Therefore, we use multi-point observations of magnetic holes by the ARTEMIS spacecraft in lunar orbit. The method we use has been previously applied to plasma jets present in the magnetosheath of Earth. The knowledge of the flow-perpendicular scale sizes is important to assess the holes’ impact on planetary magnetospheres and cometary environments.

How to cite: Plaschke, F., Volwerk, M., Karlsson, T., Götz, C., Heyner, D., Hietala, H., Mieth, J. Z. D., Schmid, D., Simon-Wedlund, C., and Vörös, Z.: On the scale sizes of magnetic holes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4366, https://doi.org/10.5194/egusphere-egu23-4366, 2023.

EGU23-4522 | Orals | ST2.2

Kinetic modeling of the interaction of solar wind discontinuities with the bow shock-magnetosheath-magnetopause system 

Jean Berchem, Giovanni Lapenta, Philippe Escoubet, and Simon Wing

Modeling the interaction of solar wind discontinuities with the bow shock-magnetosheath-magnetopause system is an important step in comprehending the effects of solar wind structures on the magnetosphere. Our procedure is to first run a global MHD simulation to predict the overall configuration of the solar wind-magnetosphere system before the discontinuity interacts with the bow shock. Then fields and plasma moments within a large sub-domain of the global MHD simulation are used to set the initial conditions of an implicit PIC simulation of the interaction of the discontinuity with the dayside magnetosphere. This procedure allows us to follow the evolution of kinetic processes as the discontinuity interacts with the bow shock and propagates through the magnetosheath before impacting the dayside magnetopause. In this presentation, we show some results of the interaction of a rotational discontinuity where the interplanetary magnetic field, initially southward, turns northward. As expected, the discontinuity slows down abruptly after interacting with the bow shock, the transverse component of the magnetic field being greatly enhanced in the process.  While the initial MHD state of the magnetosheath was laminar, kinetic waves and instabilities lead to a turbulent state for all plasma moments and electromagnetic fields. In particular, transients are observed ahead of the discontinuity as it propagates Earthward. At later stages of the simulation, the discontinuity interacts with the magnetopause. Magnetic field lines are bent strongly in the transverse direction, affecting reconnection processes with the production of large magnetic flux ropes.

How to cite: Berchem, J., Lapenta, G., Escoubet, P., and Wing, S.: Kinetic modeling of the interaction of solar wind discontinuities with the bow shock-magnetosheath-magnetopause system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4522, https://doi.org/10.5194/egusphere-egu23-4522, 2023.

EGU23-6637 | Orals | ST2.2 | Highlight

Transmission of foreshock waves through Earth's bow shock 

Lucile Turc, Owen W. Roberts, Daniel Verscharen, Andrew P. Dimmock, Primoz Kajdic, Minna Palmroth, Yann Pfau-Kempf, Andreas Johlander, Maxime Dubart, Emilia K.J. Kilpua, Kazue Takahashi, Naoko Takahashi, Markus Battarbee, and Urs Ganse

The foreshock, extending upstream of the quasi-parallel shock and populated with shock-reflected particles, is home to intense wave activity in the ultra-low frequency range. The most commonly observed of these waves are the '30-second' waves, fast magnetosonic waves propagating sunward in the plasma rest frame, but carried earthward by the faster solar wind flow. These waves are thought to be the main source of Pc3 magnetic pulsations (10-45 s periods) in the dayside magnetosphere, but how the waves can transmit through the bow shock and across the magnetosheath had remained unclear. Global hybrid-Vlasov simulations performed with the Vlasiator model provide us with the global view of foreshock wave transmission across near-Earth space. We find that the foreshock waves modulate the plasma parameters just upstream of the bow shock, which in turn periodically changes the shock compression ratio and the downstream pressure. This launches fast-mode waves propagating through the magnetosheath all the way to the magnetopause, where they can further transmit into the dayside magnetosphere. We compare our numerical results with MMS observations near the subsolar point, where we identify earthward-propagating fast-mode waves at the same period as the foreshock waves, consistent with our simulation results. Our findings show that the wave propagation across the bow shock is much more complex than the simple direct transmission of the foreshock waves which was inferred in early studies.

How to cite: Turc, L., Roberts, O. W., Verscharen, D., Dimmock, A. P., Kajdic, P., Palmroth, M., Pfau-Kempf, Y., Johlander, A., Dubart, M., Kilpua, E. K. J., Takahashi, K., Takahashi, N., Battarbee, M., and Ganse, U.: Transmission of foreshock waves through Earth's bow shock, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6637, https://doi.org/10.5194/egusphere-egu23-6637, 2023.

EGU23-6972 | Posters on site | ST2.2

How do magnetic holes cross a bow shock? Results from the kinetic hybrid plasma model Menura 

Pierre Henri, Cyril Simon Wedlund, Francesco Pucci, Etienne Behar, and Giulio Ballerini

Linear magnetic holes (LMH) are magnetic field depressions in the solar wind found everywhere in the heliosphere and sometimes downstream of planetary bow shocks. LMH, with only very little rotation of the magnetic field B across the structure, are often considered as the evolutionary endpoint of mirror modes, thus retaining certain characteristics of their parent structure: embedded in a plasma with large temperature anisotropy, large plasma beta, anticorrelation between B and the plasma density. One question is how and under which conditions these large depressions may survive a shock crossing, as observations have recently shown that such a crossing is possible. In other words: what is the interaction between two nonlinear space plasma structures that both scale as the ion gyroradius? To answer this question, we present here the first hybrid simulations of the evolution of a LMH crossing the bow shock boundary of a medium-activity comet using the hybrid Particle-In-Cell (PIC) model Menura. We first create a LMH with mirror mode characteristics in the pristine solar wind and, then, convect it down toward a comet, through the shock, into the cometary magnetosheath. We study its morphology along its path, and how the magnetosheath is impacted locally and as a whole. This work also aims at preparing fundamental space plasma physics aspects of the upcoming multi-spacecraft Comet Interceptor mission.

How to cite: Henri, P., Simon Wedlund, C., Pucci, F., Behar, E., and Ballerini, G.: How do magnetic holes cross a bow shock? Results from the kinetic hybrid plasma model Menura, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6972, https://doi.org/10.5194/egusphere-egu23-6972, 2023.

EGU23-8347 | Posters on site | ST2.2

A Statistical Study of Foreshock Environment under Radial IMF Conditions 

Gilbert Pi, Anna Salohub, Niki Xirogiannopoulou, Zdeněk Němeček, and Jana Šafránková

The foreshock is a turbulent region in front of the quasi-parallel bow shock. The reflected particles from the bow shock and interaction with oncoming waves in the solar wind create it. The foreshock is usually located at the dawn side. However, the foreshock region is relocate to the nose of the bow shock and covers all the dayside magnetospheric system when IMF points to radial or anti-radial directions. This change creates many unusual phenomena in the magnetospheric system, such as the magnetopause expansion, and generates the foreshock transients, such as spontaneous Hot Flow Anomalies (sHFA). Previous studies revealed that foreshock transients are preferred to occur under a radial IMF condition, however, what is the reason for this preference is still unclear. Using THEMIS and MMS data, the analysis presents a statistical analysis to reveal the foreshock characteristics under the radial IMF to check the reasons for the preference of foreshock transients. The primary solar wind parameters in the foreshock and/or solar wind under these conditions are revealed. The ULF wave behavior is also taken account.

How to cite: Pi, G., Salohub, A., Xirogiannopoulou, N., Němeček, Z., and Šafránková, J.: A Statistical Study of Foreshock Environment under Radial IMF Conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8347, https://doi.org/10.5194/egusphere-egu23-8347, 2023.

EGU23-8664 | ECS | Orals | ST2.2

Classifying the magnetosheath using local measurements from MMS 

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

The Earth’s magnetosheath is a dynamic region and its properties strongly depend on the angle between the bow shock normal and the solar wind magnetic field (θbn). If the shock is quasi-parallel (θbn < 45°), the magnetosheath is magnetically connected to the foreshock, causing strong fluctuations and structures propagating from upstream to downstream. A quasi-perpendicular shock (θbn > 45°) produces a less structured and more stationary magnetosheath characterized by compression and high ion temperature anisotropy. These distinct configurations make it possible to study how different plasma environments affect various processes such as turbulence, heating, and wave-particle interactions. Therefore, such studies require an accurate classification of the magnetosheath. This is not easily achieved, especially close to the magnetopause where the shock crossing for the plasma of interest cannot be observed.

Previously, Karlsson et al. (2021) used data from the Cluster mission to propose a promising classification method using local measurements of the magnetic field standard deviation, high-energy ion flux, and ion temperature anisotropy. In this work, we are building on this study and extending it to the Magnetospheric Multiscale (MMS) mission, having a different orbit than Cluster. We compare this local classification to θbn estimated from upstream conditions and well-known bow shock models, and discuss the advantages and disadvantages of the different methods.

 

Reference: Karlsson, T., Raptis, S., Trollvik, H., & Nilsson, H. (2021). Classifying the magnetosheath behind the quasi-parallel and quasi-perpendicular bow shock by local measurements. Journal of Geophysical Research: Space Physics, 126, e2021JA029269.

How to cite: Svenningsson, I., Yordanova, E., Khotyaintsev, Y. V., André, M., and Cozzani, G.: Classifying the magnetosheath using local measurements from MMS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8664, https://doi.org/10.5194/egusphere-egu23-8664, 2023.

EGU23-9082 | ECS | Orals | ST2.2

Observational Analysis of Small-scale Structures in the Earth's Magnetosheath 

Rebecca Harvey and Qiang Hu

Magnetic flux ropes with a wide range of scale sizes generally have high magnetic helicity, a magnetohydrodynamic (MHD) quantity that characterizes the knottedness of the field lines that can be used to identify flux rope structures. The identification and analysis of structures moving across boundaries such as the Earth's bow shock will give insight into how their properties change across this boundary as well as further our understanding of the interrelation between these structures. Recent spacecraft missions are returning higher time resolution data than before, allowing for more advanced studies of this phenomenon. Using high time-resolution data from the Magnetospheric Multiscale (MMS) mission and Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission, we identify small-scale flux ropes using wavelet analysis and determine how they change across boundaries. Wavelet analysis of single-spacecraft data can produce better resolved time and spatial information that will complement other methods of flux rope identification. Wavelet transforms are performed across hours-long intervals, organized by the orbit configuration of the spacecraft. The resulting spectrograms are then searched to identify small-scale structures. A number of parameters, including duration, scale size, maximum magnetic field, and average plasma temperature of the flux rope intervals identified are also recorded and summarized. Comparing the values of magnetic field, plasma beta, and other parameters at the corresponding times and locations leads to interpretations for the flux rope events such as whether they are compressed, decelerated, or undergo any other changes as they evolve.

How to cite: Harvey, R. and Hu, Q.: Observational Analysis of Small-scale Structures in the Earth's Magnetosheath, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9082, https://doi.org/10.5194/egusphere-egu23-9082, 2023.

EGU23-9423 | Orals | ST2.2

On the Speed of Interplanetary Shocks Propagating through the Magnetosheath 

Clément Moissard, Axel Bernal, Philippe Savoini, Dominique Fontaine, Ronan Modolo, Vincent David, and Bayane Michotte de Welle

Interplanetary shocks are some of the main drivers of geomagnetic storms. Before they can impact the geomagnetic environment, they propagate through the magnetosheath where their properties and geometry can be modified. What is the velocity of interplanetary shocks propagating through the magnetosheath? Previous numerical simulations and observations have given a wide range of apparently contradictory answers to this question, but they seem to all agree that interplanetary shocks generally slow down as they enter the magnetosheath: the interplanetary shocks’ velocity in the magnetosheath have been reported to be between 0.25 and 0.93 times their velocity in the solar wind. In this work, we offer two competing simple models to predict the propagation velocity of shocks through the magnetosheath. These models are applied to a list of shocks detected by currently operational spacecraft (e.g. Wind, MMS) as well as to results obtained from a hybrid PIC simulation. We show that our models both reconcile previous results and imply that interplanetary shocks could - in certain space weather-relevant situations - travel faster in the magnetosheath than they did in the solar wind. 

How to cite: Moissard, C., Bernal, A., Savoini, P., Fontaine, D., Modolo, R., David, V., and Michotte de Welle, B.: On the Speed of Interplanetary Shocks Propagating through the Magnetosheath, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9423, https://doi.org/10.5194/egusphere-egu23-9423, 2023.

EGU23-9495 | Orals | ST2.2

On the production of magnetosheath jets during a CME and SIR passage: A case study 

Luis Preisser, Ferdinand Plaschke, Florian Koller, Manuela Temmer, Owen Roberts, and Zoltan Vörös

Large scale solar wind (SW) structures called Coronal Mass Ejections (CMEs) and Stream Interaction Regions (SIRs) propagate through the interplanetary medium, where they might impact Earth and cause jet-like disturbances in the magnetosheath. Such jets are short scale structures characterized by an enhancement in dynamic pressure that propagate through the Earth’s magnetosheath (EMS) transporting mass, momentum and energy being able to affect and perturb the Earth’s magnetosphere.
Jets have been studied for 20 years, but how different SW conditions triggered by CMEs and SIRs affect jet production is a topic that has only recently begun to be studied. In this work we characterize jets observed by THEMIS during a CME and a SIR passage. We find clear differences in number and size between the jets associated with the CME regions arriving at the EMS as well as in comparison with the characteristics of jets associated with the SIR passage. Comparing WIND and THEMIS data we discuss how these differences are linked to the SW conditions in the context of a recent statistical study (Koller et al. 2022) and with different jet generation mechanisms.

How to cite: Preisser, L., Plaschke, F., Koller, F., Temmer, M., Roberts, O., and Vörös, Z.: On the production of magnetosheath jets during a CME and SIR passage: A case study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9495, https://doi.org/10.5194/egusphere-egu23-9495, 2023.

EGU23-9960 | ECS | Orals | ST2.2

Solar wind parameters influencing magnetosheath jet formation: low and high IMF cone angle regimes 

Laura Vuorinen, Heli Hietala, and Adrian T. LaMoury

Magnetosheath jets are dynamic pressure enhancements that are frequently observed downstream of the Earth's bow shock. Earthward propagating jets are significantly more likely to occur downstream of the quasi-parallel shock than the quasi-perpendicular shock. However, as the quasi-perpendicular geometry is the more common configuration at the Earth's bow shock, quasi-perpendicular jets can constitute a significant fraction of jets observed at Earth. Moreover, at other more quasi-perpendicular shock environments, such as at interplanetary shocks or the bow shocks of outer planets, they would be expected to form an even more significant portion of jets. We study the solar wind influence on jet formation in the quasi-parallel and quasi-perpendicular regimes by investigating jets in the Earth’s subsolar magnetosheath separately during low and high IMF cone angles. We find that during low IMF cone angles (downstream of the quasi-parallel shock) jet occurrence near the bow shock is not sensitive to other solar wind parameters. However, during high IMF cone angles (downstream of the quasi-perpendicular shock) jet occurrence is higher during low B, low n, high beta, and high MA conditions. This suggests that quasi-perpendicular jet formation is related to shock dynamics amplified by higher beta and MA. These observations from a wide range of solar wind parameters also allow us to make predictions of jet occurrence at other planetary systems.

How to cite: Vuorinen, L., Hietala, H., and LaMoury, A. T.: Solar wind parameters influencing magnetosheath jet formation: low and high IMF cone angle regimes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9960, https://doi.org/10.5194/egusphere-egu23-9960, 2023.

EGU23-10536 | ECS | Orals | ST2.2 | Highlight

MAVEN Observations of Steepened Ultra-Low Frequency Waves in the Upstream Martian Foreshock Region 

Gangkai Poh, Jared Espley, Shaosui Xu, Guan Le, Norberto Romanelli, Jasper Halekas, Gina DiBraccio, and Jacob Gruesbeck

In this study, we present the analysis of steepened ultra-low frequency (ULF) waves in the foreshock region upstream of Mars’ bow shock observed by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft at Mars. A survey of MAVEN magnetic field and plasma measurements shows quasi-periodic gradual increases followed by a sharp decrease in the magnetic field magnitude (Btotal). Higher frequency waves were also commonly, but not always, observed at the trailing edge of the large-amplitude increase in Btotal. These observations are consistent with the signatures of shocklets observed in the solar wind region upstream of Earth’s and planetary bow shocks. Shocklets are believed to be formed as a result of the steepening of fast magnetosonic waves generated by reflected ions in the quasi-parallel foreshock region. We also performed the minimum variance analysis (MVA) and statistical analysis technique to determine the wave properties (e.g. polarization, wave propagation, amplitude and frequency) of the shocklets and higher frequency waves observed in its trailing edge. Our results showed that these shocklets are left-handed polarized in the spacecraft frame, with mean amplitude δB/B of ~3.5 and time separation between adjacent shocklet events of ~40s. We also analyzed measurements (ions and electrons) from MAVEN’s plasma instruments to investigate the energization process of the particles during the observations of shocklets. We will discuss the possible generation mechanisms for these steepened ultra-low frequency waves at Mars, and any implications for the martian plasma environment downstream of Mars’ bow shock. 

How to cite: Poh, G., Espley, J., Xu, S., Le, G., Romanelli, N., Halekas, J., DiBraccio, G., and Gruesbeck, J.: MAVEN Observations of Steepened Ultra-Low Frequency Waves in the Upstream Martian Foreshock Region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10536, https://doi.org/10.5194/egusphere-egu23-10536, 2023.

EGU23-10616 | ECS | Orals | ST2.2

Generation of sub-ion scale magnetic holes from electron shear flow instabilities in plasma turbulence 

Giuseppe Arrò, Francesco Pucci, Francesco Califano, and Giovanni Lapenta

Magnetic holes are coherent structures associated with a strong depression in the magnetic field amplitude. Such structures are ubiquitous in space plasmas and are observed in the solar wind, in planetary bow shocks and magnetosheaths, in the Earth's magnetotail and around comets. Magnetic holes may have very different sizes and properties. The largest ones have a size of hundreds of ion gyroradii while the smallest ones are sub-ion scale structures of the order of a few electron gyroradii. The drop in magnetic field amplitude associated with magnetic holes is often sustained by an increase in plasma density and enhanced ion and electron temperature anisotropies, with temperatures that are typically higher in the plane perpendicular to the local magnetic field. These properties seem to suggest that the generation of magnetic holes may result from the nonlinear evolution of mirror modes whose growth is fed by perpendicular temperature anisotropies and that are characterized by anticorrelated magnetic field and density perturbations. Some observational and numerical studies seem to support the idea of a scenario in which magnetic holes are generated by the mirror instability but in many cases this picture is not consistent with observations, especially in the case of sub-ion scale magnetic holes for which a number of possible generation mechanisms have been considered. Hence, the origin of magnetic holes is still controversial and under debate. 

Plasma turbulence is also known as a driver for the generation of coherent structures and may play a key role in the formation of magnetic holes, especially in the solar wind and in the Earth's magnetosheath that are in a turbulent state. Indeed, numerical simulations of plasma turbulence show that sub-ion scale magnetic holes can develop self-consistently out of small scale magnetic fluctuations that locally reduce the magnetic field amplitude and trap hot electrons. However, it is still unclear how such small scale fluctuations can emerge in a turbulent plasma where energy is typically injected at large scales. In this work, we study the formation of sub-ion scale magnetic holes by means of fully kinetic particle-in-cell simulations of plasma turbulence. We show that by injecting energy at scales relatively large with respect to ion scales, the turbulence naturally tends to generate sub-ion scale electron velocity shear layers associated with elongated magnetic field grooves. These elongated magnetic dips then become unstable and break up into sub-ion scale magnetic holes characterized by an intense azimuthal electron current and a strong perpendicular electron temperature anisotropy. We show that the properties of magnetic holes generated by this mechanism are consistent with satellite observations. Our results may provide a possible explanation of how magnetic holes develop in a realistic turbulent environment.

How to cite: Arrò, G., Pucci, F., Califano, F., and Lapenta, G.: Generation of sub-ion scale magnetic holes from electron shear flow instabilities in plasma turbulence, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10616, https://doi.org/10.5194/egusphere-egu23-10616, 2023.

EGU23-10625 | ECS | Orals | ST2.2

Modification of magnetosheath jet occurrence and properties within CMEs and SIRs 

Florian Koller, Ferdinand Plaschke, Luis Preisser, Manuela Temmer, Owen Roberts, and Zoltan Vörös

Large-scale solar wind (SW) structures like coronal mass ejections (CMEs) and stream interaction regions (SIRs) significantly alter the plasma within the Earth’s magnetosheath and change the foreshock region. Thus, they modulate the number and the parameters of dynamic pressure transients in the magnetosheath, which we call magnetosheath jets. We use THEMIS spacecraft data from 2008 to 2022 to detect these jets in the magnetosheath and OMNI data for the SW within the same time range. We investigate which properties in each SW structure primarily influence the jet occurrence. We find that CMEs cause a reduction in jet occurrence due to the mix of high magnetic field strength, high plasma beta, low Mach number, and high cone angles. These conditions most likely disrupt the building of a proper foreshock region and thus hinder the major generation mechanism for jets in the magnetosheath. On the other hand, high speed streams in SIRs show favorable conditions for jet generation in all plasma parameters, most importantly due to the high probability for low cone angles, the low density, high velocity, and low magnetic field strength. We analyze how the jet parameters differ in each type of  SW structure and discuss how this influences the geoeffectiveness of jets.

How to cite: Koller, F., Plaschke, F., Preisser, L., Temmer, M., Roberts, O., and Vörös, Z.: Modification of magnetosheath jet occurrence and properties within CMEs and SIRs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10625, https://doi.org/10.5194/egusphere-egu23-10625, 2023.

EGU23-11073 | Orals | ST2.2

Probing the foreshock wave boundary 

Seth Dorfman, Kun Zhang, Lucile Turc, Urs Ganse, and Minna Palmroth

Foreshock ultralow frequency (ULF) waves play an important role in the dynamics upstream of planetary bow shocks and can affect the downstream magnetosheath region.  Due to limited available spacecraft measurements, the waves are often analyzed with incomplete information about their overall spacial structure. Common wave vector analysis techniques built around these limitations often invoke the divergence free condition of the magnetic field without considering the possibility that the wave amplitude profile could have a strong spacial dependence.  We explore the consequences of this assumption in the Earth's ion foreshock using both ARTEMIS spacecraft data and a 2-D hybrid Vlasov simulation conducted using the Vlasiator code.  The observed foreshock ULF waves have a finite extent in the direction perpendicular to the Interplanetary Magnetic Field, and incorrect application of standard techniques at the boundary yields a false wave vector orientation that may be used as a novel edge detection method.  Our results stand as a cautionary tale for wave analysis in other space physics contexts where the wave geometry is less clear.

Supported by NASA Grant 80NSSC20K0801. Vlasiator is developed by the European Research Council Starting grant 200141-QuESpace, and Consolidator grant GA682068-PRESTISSIMO received by the Vlasiator PI. Vlasiator has also received funding from the Academy of Finland. See www.helsinki.fi/vlasiator

How to cite: Dorfman, S., Zhang, K., Turc, L., Ganse, U., and Palmroth, M.: Probing the foreshock wave boundary, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11073, https://doi.org/10.5194/egusphere-egu23-11073, 2023.

EGU23-12129 | ECS | Posters on site | ST2.2

Global 3D simulation of the interaction between a turbulent solar wind and a magnetic dipole 

Etienne Behar, Pierre Henri, Giulio Ballerini, Francesco Pucci, and Cyril Simon-Wedlund

Far from an ideal laminar flow, the solar wind impacting planetary magnetospheres contains a spectrum of fluctuations extending to virtually all scales. The study of the effects of such fluctuations on a magnetosphere was until recently lacking a numerical tool which would provide a self-consistent global picture of such an interaction. Using a novel 2-step approach, the open source, hybrid-PIC code Menura is employed to first develop a 3D turbulent cascade in an otherwise homogeneous plasma, to then inject this turbulent solution in a domain containing a permanent dipole. We show how solar wind turbulence is affected by the crossing of the shock, and conversely how the global shape of the magnetosphere is evolving compared to its laminar counterpart. We additionally highlight how transient phenomena and coherent structures are naturally occurring in the foreshock and the sheath due to the local direction of the turbulent magnetic field.

How to cite: Behar, E., Henri, P., Ballerini, G., Pucci, F., and Simon-Wedlund, C.: Global 3D simulation of the interaction between a turbulent solar wind and a magnetic dipole, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12129, https://doi.org/10.5194/egusphere-egu23-12129, 2023.

EGU23-12611 | Posters on site | ST2.2

Kinetic effects and their role on the entry and transport of finite-size plasma jets inside the Hermean magnetosphere 

Gabriel Voitcu, Marius Echim, Eliza Teodorescu, and Costel Munteanu

The dynamics of finite-size plasma irregularities/jets streaming across magnetic discontinuity regions, as the magnetopause, is a key process for better understanding the transport of mass, momentum and energy from the solar wind towards planetary magnetospheres. In this paper we investigate the kinetic effects and their role on the entry and transport of localized solar wind/magnetosheath plasma structures inside the Hermean magnetosphere under northward orientation of the interplanetary magnetic field. For this purpose, we use three-dimensional particle-in-cell simulations adapted to the interaction between plasma elements/irregularities/jets of finite spatial extent and the typical magnetic field of Mercury’s magnetosphere. Our simulations reveal the penetration of solar wind plasma across the Hermean magnetopause and transport inside the magnetosphere. The entry process is controlled by the magnetic field increase at the magnetopause. For reduced jumps of the magnetic field (i.e. for larger values of the interplanetary magnetic field), the magnetospheric penetration is enhanced. The equatorial dynamics of the plasma element is characterized by a dawn-to-dusk asymmetry, the braking being stronger in the dawn flank. More plasma penetrates into the dusk flank and advances deeper inside the magnetosphere than in the dawn flank. The simulation results are discussed in the context of the impulsive penetration mechanism.

How to cite: Voitcu, G., Echim, M., Teodorescu, E., and Munteanu, C.: Kinetic effects and their role on the entry and transport of finite-size plasma jets inside the Hermean magnetosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12611, https://doi.org/10.5194/egusphere-egu23-12611, 2023.

EGU23-15140 | ECS | Posters on site | ST2.2

Morphology case study of magnetic holes in the pristine solar wind 

Henriette Trollvik, Tomas Karlsson, and Savvas Raptis

Magnetic holes (MHs) are deep depressions in the magnetic field found in the solar wind and in planetary magnetosheaths. Based on Cluster multi-point data from the pristine solar wind, we investigate the morphology of MHs exhibiting no to little rotation in the magnetic field (linear MHs). We introduce a new coordinate system, to better see the variation in the structure, and to be able to connect to solenoid-based models. We will present two events; One is an event where the observations suggest a long cylindrical shape, where the observations are compared to an infinitely long solenoid model. For this event we only consider a 2D model. The other event is where the observations suggest a truncated cylinder shape, where the event is compared to a 3D model of a truncated solenoid. We will show how well the models are able to reconstruct the observations and present some results. 

How to cite: Trollvik, H., Karlsson, T., and Raptis, S.: Morphology case study of magnetic holes in the pristine solar wind, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15140, https://doi.org/10.5194/egusphere-egu23-15140, 2023.

EGU23-15282 | Orals | ST2.2

Morphology and evolution of foreshock structures in a high-Mach number hybrid-Vlasov simulation of Earth's magnetosphere 

Markus Battarbee, Martin Archer, Heli Hietala, Ferdinand Plaschke, Minna Palmroth, and Lucile Turc and the the Vlasiator team

Counter-streaming particles reflected from the Earth's bow shock towards the Sun build up the ion foreshock, exciting right-handed ultra-low frequency (ULF) waves, which convect with the solar wind back to the bow shock. As these waves move Earthward, they steepen and interact with each other, forming a complex wave field consisting of various foreshock structures. Observations of foreshock structures have classified them as, for example, ULF waves, shocklets, short large-amplitude magnetic structures (SLAMS), cavitons, and spontaneous hot flow anomalies (SHFAs). We present results from a high Mach number 2D-3V hybrid-Vlasov Vlasiator simulation of the Earth's bow shock and foreshock during quasi-radial IMF and place them in the context of spacecraft observations. We combine spatial analysis of bulk characteristics within the foreshock with virtual spacecraft observations to evaluate the morphology of foreshock structures as they form, and how they subsequently evolve as they approach the Earth's bow shock.

How to cite: Battarbee, M., Archer, M., Hietala, H., Plaschke, F., Palmroth, M., and Turc, L. and the the Vlasiator team: Morphology and evolution of foreshock structures in a high-Mach number hybrid-Vlasov simulation of Earth's magnetosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15282, https://doi.org/10.5194/egusphere-egu23-15282, 2023.

EGU23-1047 | Posters on site | ST2.3

Observation of the Large‐Amplitude andFast‐Damped Plasma Sheet FlappingTriggered by Reconnection‐InducedBallooning Instability 

Yongcun Zhang, Lei Dai, Zhaojin Rong, Chi Wang, Henri Reme, Iannis Dandouras, Chris Carr, and Philippe Escoubet

 In this study, we reported the large‐amplitude and fast‐damped flapping of the plasma sheet,
which co‐occurred with magnetic reconnection. Data from the Double Star TC‐1 and Cluster satellites
were used to analyze the features of the plasma sheet flapping 1.4 R
E earthward of an ongoing magnetic
reconnection event. The flapping was rapidly damped, and its amplitude decreased from the
magnetohydrodynamics scale to the subion scale in 5 min. The variation in the flapping period (from 224 to
20 s) indicated that the source of the flapping had highly dynamic temporal characteristics. The plasma sheet
flapping propagated duskward through a kink‐like wave with a velocity of 100 km/s, which was in
agreement with the group velocity of the ballooning perturbation. A correlation analysis between the
magnetic reconnection and plasma sheet flapping indicated that the magnetic reconnection likely facilitated
the occurrence of ballooning instability by altering the state of plasma in the downstream plasma sheet. In
this regard, the reconnection‐induced ballooning instability could be a potential mechanism to generate
the flapping motion of the plasma sheet.
 

How to cite: Zhang, Y., Dai, L., Rong, Z., Wang, C., Reme, H., Dandouras, I., Carr, C., and Escoubet, P.: Observation of the Large‐Amplitude andFast‐Damped Plasma Sheet FlappingTriggered by Reconnection‐InducedBallooning Instability, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1047, https://doi.org/10.5194/egusphere-egu23-1047, 2023.

EGU23-1110 | Posters on site | ST2.3

Deformations at Earth's dayside magnetopause under quasi-radial IMF: implications for the SMILE soft X-ray imaging 

Zhongwei Yang, Xiaocheng Guo, Tianran Sun, Riku Jarvinen, George K. Parks, Can Huang, Hui Li, and Chi Wang

The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) is a Chinese Academy of Science (CAS) and European Space Agency (ESA) collaborative science mission. Primary goals are investigating the dynamic response of the Earth’s magnetosphere to the solar wind (SW) impact via simultaneous in situ SW/magnetosheath plasma and magnetic field measurements, X-Ray images of the magnetosheath and magnetic cusps, and UV images of global auroral distributions.  Recently, soft X-ray emissions from SW charge exchange (SWCX) at Earth’s magnetosphere has been investigated using XMM-Newton observations (Zhang et al., ApJL, 2022). Their results reveal that heavy ions (e.g., O7+) have relatively discrete and intense spectral lines, which can be more easily captured by soft-X ray instrument. Another striking point is that the fitted X-ray flux emitted by the ion line is sensitive and correlated to some physical values of SW bulk speed and density. To obtain physical quantities self-consistently for SW heavy ions, a three-dimensional global hybrid model has been developing. Based on Zoltan, ParGrid, and Corsair, we have developing a three-dimensional hybrid model of the terrestrial magnetosphere combining several modules: e.g., open boundaries with different particle injectors, cold plasma model for the inner magnetosphere, magnetosphere-ionosphere coupling module, and vtk format IO etc. In this poster, we will present preliminary results on the global dynamics of proton and heavy ions from the Earth’s bow shock all the way to the magnetopause under quasi-radial IMF conditions. This research focuses on 3-D profiles of key physical parameters, such as the magnetosheath ion pressure and high speed jets. And the resulting deformation of the magnetopause also will be discussed. Heavy ion behaviors at above dynamic/kinetic structures may play important roles in their soft X-ray emission during the interaction between SW heavy ions and the Earth’s exosphere (mainly populated by neutral hydrogen atoms). Thence, we will represent and compare the soft-X ray imaging calculated by heavy-ion data and proton data, respectively.

How to cite: Yang, Z., Guo, X., Sun, T., Jarvinen, R., Parks, G. K., Huang, C., Li, H., and Wang, C.: Deformations at Earth's dayside magnetopause under quasi-radial IMF: implications for the SMILE soft X-ray imaging, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1110, https://doi.org/10.5194/egusphere-egu23-1110, 2023.

Interplanetary parameters such as solar wind and interplanetary magnetic fields (IMF) drive the shape and size of the magnetopause jointly, which has complex relationships. In this study, we proposed an interpretable machine learning procedure to disentangle the influences of interplanetary parameters on the magnetopause standoff distance (MSD) and sort their importance in the MSD simulation. A magnetopause crossings database from the THEMIS satellites and interplanetary parameters from OMNI during the period of 2007-2016 are utilized to construct machine learning magnetopause models. SHapley Additive exPlanations (SHAP) is the basis of the interpretable procedure, which introduces interpretability and makes the machine learning magnetopause model to be a “white box”. The solar wind dynamic pressure and IMF BZ are widely considered the top two important parameters that drive the MSD. However, the interpretable procedure suggests that the IMF magnitude (i.e. strength of the IMF) leads BZ as the second most important interplanetary driver. This ranking result is unexpected, and it implies that the role of IMF magnitude is underestimated although magnetic pressure, which is a function of the IMF magnitude was considered in previous studies. The examination of disentangled effects of interplanetary parameters reveals that the combined influence of the IMF magnitude and BZ can cause an MSD sag near BZ = 5 nT. This is for the first time we conduct the interpretable concept into the machine learning model in the study of the magnetosphere.

How to cite: Li, S. and Sun, Y.-Y.: Interpretable Machine Learning Procedure Unravels Hidden Interplanetary Drivers of the Low Latitude Dayside Magnetopause, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1660, https://doi.org/10.5194/egusphere-egu23-1660, 2023.

EGU23-1863 | ECS | Orals | ST2.3

Statistical study of extreme magnetopause locations 

Niklas Grimmich, Ferdinand Plaschke, Martin Archer, Daniel Heyner, Johannes Mieth, Rumi Nakamura, and David Sibeck

The magnetopause (MP) is the boundary that separates the solar wind plasma from the Earth’s (inner) magnetosphere. To first order, its equilibrium position is defined by the pressure balance across it. The boundary moves under the influence of varying solar wind conditions and transient foreshock phenomena, thereby sometimes reaching unusually large and small distances from Earth. We investigate the occurrence of such extreme MP distortions. Therefore, we construct a database of magnetopause crossings observed by the THEMIS spacecraft in the years 2007 to mid-2022 using machine learning techniques. Crossing events deviating from the Shue et al. (1998) MP model by more than the reported uncertainties are denoted as extreme distortions. The occurrences of these extreme events in terms of expansion or compression of the magnetosphere are linked to different solar wind parameters. The results should be applied to future magnetopause models and may be validated by MP observations in soft x-ray images by the upcoming SMILE mission.

How to cite: Grimmich, N., Plaschke, F., Archer, M., Heyner, D., Mieth, J., Nakamura, R., and Sibeck, D.: Statistical study of extreme magnetopause locations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1863, https://doi.org/10.5194/egusphere-egu23-1863, 2023.

EGU23-1978 | Orals | ST2.3 | Highlight

Effects of electron particle physics in global planetary models 

Giovanni Lapenta, Dave Schriver, Hanne Baeke, Nicole Echterling, Ray Walker, Mostafa El Alaoui, and Pavel Travnicek

We compare global models of Mercury done with the hybrid (particle ions and fluid electrons) and full kinetic (particles are used for both electrons and ions) models. We use the implicit particle in cell method based on the ECsim algorithm [1]. We study how energy exchanges in the magnetosphere of the planet are changed by representing the electrons as particles. We observe a more powerful energy exchange due to the presence of stronger features, larger more localised electron currents and sharper interfaces. The electron and also the ion energisation  is more intense leading to an overall increase of the energy transfer from the solar wind to the planetary magnetosphere. The electron distribution is far from Maxwellian, showing effects that cannot be captured by hybrid models such as the the presence of crescents, flat-top and multi beam distributions. Full particle models also provide more accurate description of reconnection. Using the electron agyrotropy, the new Lorentz indicator [2] and a new machine learning method [3], we investigate how reconnection is linked with current sheets, studying where and when reconnection happens and distinguishing electron from ion- scale reconnection. 

 

 

[1] Lapenta, G., Schriver, D., Walker, R. J., Berchem, J., Echterling, N. F., El Alaoui, M., & Travnicek, P. (2022). Do We Need to Consider Electrons' Kinetic Effects to Properly Model a Planetary Magnetosphere? The Case of Mercury. Journal of Geophysical Research: Space Physics, 127(4), e2021JA030241.

[2] Lapenta, G. (2021). Detecting reconnection sites using the Lorentz Transformations for electromagnetic fields. The Astrophysical Journal, 911(2), 147.

[3] Lapenta, G., Goldman, M., Newman, D. L., & Eriksson, S. (2022). Formation and Reconnection of Electron Scale Current Layers in the Turbulent Outflows of a Primary Reconnection Site. The Astrophysical Journal, 940(2), 187.

How to cite: Lapenta, G., Schriver, D., Baeke, H., Echterling, N., Walker, R., El Alaoui, M., and Travnicek, P.: Effects of electron particle physics in global planetary models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1978, https://doi.org/10.5194/egusphere-egu23-1978, 2023.

EGU23-1984 | Orals | ST2.3

Extreme Birkeland currents are more likely during geomagnetic storms on the dayside of the Earth 

John Coxon, Gareth Chisham, Mervyn Freeman, Colin Forsyth, Maria-Theresia Walach, Kyle Murphy, Sarah Vines, and Brian Anderson
We combine methods to identify substorms and geomagnetic storms into a single, novel method that identifies four categories: quiet times, storm only, substorm only, substorms in storms. We employ Birkeland current density data from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) between 2010–2017 and use our new combined identification method to sort data in this range into one of the four categories. We then subsample such that each category comprises the same number of data, in order that each category behaves statistically similarly.
 
We then examine the large global behaviour of each category for the first time. We find that the mean current density is larger during substorms and its standard deviation is larger during geomagnetic storms. We assess the kurtosis and variance of the underlying distributions, and determine that the kurtosis is far higher during geomagnetic storms than during substorms. We use the survival function to quantify the probability of current densities above set thresholds and find that current densities which are above a low threshold are more likely during substorms, but that extreme currents are far more likely during geomagnetic storms.
 
We shift the data into an adaptive coordinate system defined by the boundary between Regions 1 and 2 Birkeland current and demonstrate that extreme currents are most likely to flow within Region 2 current during geomagnetic storms. This is consistent with the literature on geomagnetic storms driving extreme behaviour, but unexpected in a paradigm of the current systems in which Region 1 current is generally larger.

How to cite: Coxon, J., Chisham, G., Freeman, M., Forsyth, C., Walach, M.-T., Murphy, K., Vines, S., and Anderson, B.: Extreme Birkeland currents are more likely during geomagnetic storms on the dayside of the Earth, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1984, https://doi.org/10.5194/egusphere-egu23-1984, 2023.

EGU23-2354 | ECS | Orals | ST2.3 | Highlight

Hybrid-Vlasov simulation of soft X-ray emissions at the Earth's dayside magnetospheric boundaries 

Maxime Grandin, Hyunju K. Connor, Sanni Hoilijoki, Markus Battarbee, Yann Pfau-Kempf, Urs Ganse, Konstantinos Papadakis, and Minna Palmroth

Solar wind charge exchange produces emissions in the soft X-ray energy range which can enable the study of near-Earth space regions such as the magnetopause, the magnetosheath and the polar cusps by remote sensing techniques. The Solar wind–Magnetosphere–Ionosphere Link Explorer (SMILE) mission aims to obtain soft X-ray images of near-Earth space thanks to its Soft X-ray Imager (SXI) instrument. While earlier modelling works have already simulated soft X-ray images as might be obtained by SMILE SXI during its mission, the numerical models used so far are all based on the magnetohydrodynamics description of the space plasma. To investigate the possible signatures of ion-kinetic-scale processes in soft X-ray images, we use for the first time a global hybrid-Vlasov simulation of the geospace from the Vlasiator model. The simulation is driven by fast and tenuous solar wind conditions and purely southward interplanetary magnetic field. We first produce global images of the dayside near-Earth space by placing a virtual imaging satellite at two different locations, providing meridional and equatorial views. We then analyse regional features present in the images and show that they correspond to signatures in soft X-ray emissions of mirror-mode wave structures in the magnetosheath and flux transfer events (FTEs) at the magnetopause. Our results suggest that, although the time scales associated with the motion of those transient phenomena will likely be significantly smaller than the integration time of SMILE SXI, mirror-mode structures and FTEs can collectively produce detectable signatures in the soft X-ray images. For instance, a local increase by 30% in the proton density at the dayside magnetopause resulting from the transit of multiple FTEs leads to a 12% enhancement in the line-of-sight- and time-integrated soft X-ray emissivity originating from this region. Likewise, a proton density increase by 14% in the magnetosheath associated with mirror-mode structures can result in an enhancement in the soft X-ray signal by 4%. These are likely conservative estimates, given that the solar wind conditions used in the Vlasiator run can be expected to generate weaker soft X-ray emissions than the more common denser solar wind. These results will contribute to the preparatory work for the SMILE mission by providing the community with quantitative estimates of the effects of small-scale, transient phenomena occurring on the dayside.

How to cite: Grandin, M., Connor, H. K., Hoilijoki, S., Battarbee, M., Pfau-Kempf, Y., Ganse, U., Papadakis, K., and Palmroth, M.: Hybrid-Vlasov simulation of soft X-ray emissions at the Earth's dayside magnetospheric boundaries, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2354, https://doi.org/10.5194/egusphere-egu23-2354, 2023.

EGU23-2460 | Posters on site | ST2.3 | Highlight

Tracking the Subsolar Bow Shock and Magnetopause 

David Sibeck and Marcos Silveira

Global magnetohydrodynamic models predict that plasma velocities vary almost linearly from 0 km s-1 at the stationary subsolar magnetopause to ~0.25 VSW at the subsolar bow shock, where VSW is the solar wind velocity.  We show how two-point measurements of the plasma velocity  within ~15° of the Sun-Earth line can be used to determine gradients in the plasma velocity and consequently the time-dependent location of both the subsolar magnetopause and the subsolar bow shock.  A case study employing multiple simultaneous THEMIS spacecraft observations confirms that velocity gradients in the subsolar magnetosheath are linear, except when spacecraft observe rapid fluctuations downstream from the quasi-parallel bow shock.  The method may be useful to those binning magnetosheath observations to develop empirical models, those seeking to determine whether reconnection and hence magnetopause erosion are steady or bursty, and those determining the stand-off distance of the bow shock (or equivalently the polytropic index in the solar wind).

How to cite: Sibeck, D. and Silveira, M.: Tracking the Subsolar Bow Shock and Magnetopause, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2460, https://doi.org/10.5194/egusphere-egu23-2460, 2023.

EGU23-3157 | ECS | Posters on site | ST2.3

Non-uniform structures in the solar wind and its interaction with the Earth’s magnetosphere 

Kostiantyn Grygorov, Zdeněk Němeček, and Jana Šafránková

The solar wind prediction in front of the Earth relies on the spacecraft observations at the L1 point. In the last decade, the Wind and ACE missions orbiting around the L1 point were accompanied with the DSCOVR spacecraft. This configuration allows determination of the spatial structure of solar wind discontinuities that in turn impact the Earth. Processes in the heliospheric current sheet can produce structures with scales comparable to the entire dayside magnetosphere and such structures can be misinterpreted using OMNI data that are based on observations in one point only. In this study, we present the tracing of such inhomogeneous structures in the solar wind from L1 toward the Earth. We analyze in details their manifestation in the magnetosheath, at the magnetopause and inside the magnetosphere with motivation to more precisely determine the shape and location of magnetospheric boundaries. Moreover, we investigate the mechanisms leading to creation and development of such structures in the solar wind.

How to cite: Grygorov, K., Němeček, Z., and Šafránková, J.: Non-uniform structures in the solar wind and its interaction with the Earth’s magnetosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3157, https://doi.org/10.5194/egusphere-egu23-3157, 2023.

EGU23-3225 | Orals | ST2.3 | Highlight

Extreme magnetopause locations and their sources 

Zdenek Nemecek, Jana Šafránková, Kostiantyn Grygorov, Gilbert Pi, Maryam Aghabozorgi Nafchi, František Němec, and Jiří Šimůnek

Magnetopause is a critical boundary dividing the space controlled by the Earth magnetic field from the solar wind and interplanetary magnetic field. Its position is controlled mainly by the solar wind dynamic pressure and north-south IMF component and these quantities are included in a variety of empirical magnetopause models. Comparison of observed magnetopause locations with model predictions can serve as a proof of our understanding of the interaction between solar wind and Earth magnetic field. Since the corresponding upstream conditions are usually derived from observation at L1, our knowledge on solar wind propagation and evolution on short scales are tested as well. We have collected about 40 000 of dayside magnetopause crossings observed by THEMIS, Cluster and Geotail spacecraft in course of 2007–2019 years and compared the observed magnetopause position with prediction of several empirical magnetopause models using OMNI upstream parameters. The difference between observed and predicted magnetopause radial distance, Robs - Rmod was used for quantification of the model-observation agreement. We have found that the median values of Robs – Rmod are well predicted by the tested models till Robs≈12 Re for all models but large positive deviations were found for larger magnetopause distances. A detailed analysis of such events revealed that they are connected with transient magnetopause displacements caused by magnetosheath perturbations of large amplitude and we are searching for their sources.

How to cite: Nemecek, Z., Šafránková, J., Grygorov, K., Pi, G., Aghabozorgi Nafchi, M., Němec, F., and Šimůnek, J.: Extreme magnetopause locations and their sources, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3225, https://doi.org/10.5194/egusphere-egu23-3225, 2023.

EGU23-3234 | ECS | Posters on site | ST2.3

Interplanetary magnetic field effects on the magnetopause location 

Maryam Aghabozorgi Nafchi, František Němec, Gilbert Pi, Zdeněk Němeček, Jana Šafránková, Kostiantyn Grygorov, and Jiří Šimůnek

We use a large set of nearly 15,000 subsolar magnetopause crossings identified in the THEMIS A-E, Magion 4, Geotail, and Interball-1 satellite data to analyze the effect of interplanetary magnetic field (IMF) on the location of the magnetopause. Differences between the observed and empirical model magnetopause distances are used to account for the magnetopause distance variations due to the changes in the solar wind dynamic pressure. It is shown that not only the IMF Bz component but also the IMF clock angle has a significant effect on the magnetopause location, which is not included in traditional empirical models. Additionally, IMF By component can cause considerable dawn-dusk asymmetry in the shape of the magnetopause at times of very low Alfvén Mach numbers (MA<4). Both the magnitude and orientation of the IMF By component seem to affect the magnetopause distance. The obtained results are consistent with a global MHD model run at the Community Coordinated Modeling Center (CCMC).

How to cite: Aghabozorgi Nafchi, M., Němec, F., Pi, G., Němeček, Z., Šafránková, J., Grygorov, K., and Šimůnek, J.: Interplanetary magnetic field effects on the magnetopause location, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3234, https://doi.org/10.5194/egusphere-egu23-3234, 2023.

EGU23-3924 | Orals | ST2.3

Velocity gradient method applied to magnetosheath observations 

Marcos Silveira, David Sibeck, and Flavia Cardoso

In plasma physics, boundaries play a crucial role separating regions with different plasma regimes. The Earth’s magnetopause is the outermost boundary of the magnetospheric magnetic field, it is defined by the pressure equilibrium between the magnetosheath and the magnetosphere. Similar importance has the bow shock, separating the supersonic solar wind from the magnetosheath plasma. Even though there are satellite missions able to measure locations and other magnetopause/bow shock properties in-situ, most of the time they are somewhere else. Numerical models predict that after crossing the bow shock in the subsolar region the Vx component of the solar wind velocity decreases linearly until zero where it encounters the subsolar magnetopause. When this assumption is valid, it is possible to determine the boundary location using radial gradient measurements of the magnetosheath plasma velocity made deep in the magnetosheath, away from the boundaries. We will present cases where the bow shock and magnetopause stand-off locations are determined using remote multipoint THEMIS magnetosheath velocity observations.  We will define when and where the method is effective.  We will compare results with the predictions of global MHD simulations.

How to cite: Silveira, M., Sibeck, D., and Cardoso, F.: Velocity gradient method applied to magnetosheath observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3924, https://doi.org/10.5194/egusphere-egu23-3924, 2023.

EGU23-3960 | Posters virtual | ST2.3

Statistical study of substorm recovery phases  in the inner magnetosphere and magnetotail 

Sanjay Kumar, Tuija Pulkkinen, DiMarco Connor, and Austin Brenner

Magnetospheric substorm is recognized as an important mechanism for transferring and dissipating solar wind energy to the ionosphere and near-Earth regions. A substorm is generally thought to consist of three phases: growth phase, expansion phase, and the recovery phase, and the total duration of a substorm is about 2–4 hour. In this work, we present a statistical study of the magnetotail state during different phases of substorms, recovery phase in particular, for a period of 5 years from 2016-2020 using multi-spacecraft and ground magnetic measurements. For best spatial and temporal coverage of the inner magnetosphere and magnetotail, we use THEMIS, RBSP, MMS mission observations complemented by the SuperMAG database of measurements from ground-based magnetometers. To examine the duration of substorm expansion and recovery phases in the ionosphere, inner magnetosphere and magnetotail, we first find the substorm peak and end times from a list of substorm onsets available on the SuperMAG website. Substorm peak corresponds to the peak intensity of the westward electrojet provided by the SML (SuperMAG AL) index. For the current analysis period, we obtain a few thousand events when there are at least two spacecraft in the tail, which provides good statistics. To determine the time scales of expansion and recovery phases in the inner magnetosphere and magnetotail, we divide the observations into different bins based on X and Y position of the spacecraft. Keeping focus at the center of the tail, i. e., -5 < Y < 8 RE, the bins are chosen to be -4 to -7 RE, -7 to -10 RE, -10 to -15 RE, and -15 to -25 RE. A superposed epoch analysis is performed on the IGRF field subtracted ($ \Delta Bz =Bz_{Measured}- Bz_{IGRF}$) $Bz$ component of observed magnetic field for complete period of analysis. To find the time scale for recovery phase, we center the superposed epoch around the peak time. Our results show that the timescale of the field recovery is  more than an hour near the geostationary orbit (-4 to -7 RE), 30 min to less than an hour in the range -7 to -10 RE and even shorter as we go beyond -10 RE. The results presented in this work will help understand the spatial and temporal evolution of substorms in the magnetotail, and will significantly improve our understanding of space physics.

How to cite: Kumar, S., Pulkkinen, T., Connor, D., and Brenner, A.: Statistical study of substorm recovery phases  in the inner magnetosphere and magnetotail, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3960, https://doi.org/10.5194/egusphere-egu23-3960, 2023.

EGU23-4032 | Orals | ST2.3 | Highlight

Mysterious geomagnetic response to minor solar wind disturbance: Observations 

Stavros Dimitrakoudis, Masatoshi Yamauchi, Johnsen Magnar G., Escoubet Philippe, Araki Tohru, Raita Tero, Mann Ian R., Dandouras Iannis, Lindqvist Per-Arne, and Carr Christopher M.

On 15 April 2022, the Kiruna magnetometer detected an isolated geomagnetic spike of 400 nT with rising time of 2 minutes. This is on the same level of large sudden commencements (historically largest one is about 1000 nT in Kiruna), but this event was not followed by any magnetic storm or substorm.  In this sense, the observed 400 nT spike is unique in the history of Kiruna magnetometer (more than 30 years of digital data). At the same time, the Kiruna riometer detected a strong absorption with short rise time, indicating a sudden increase of the electron density. 

 

The world-wide geomagnetic observations available at IMAGE, SuperMAG and INTERMAGNET geomagnetic networks, show isolated localised geomagnetic spikes in the dawn sector in both hemispheres, but not in the dusk sector, gradually moving toward midnight with decreasing intensity.  Detailed analyses of geomagnetic deviation in the northern hemisphere indicates strong shear in the ionospheric Hall current with the sense of downward field.  Considering its location and electron density increase, this field-aligned current is most likely caused by the ring current particles, as is indicated by DMSP data.

 

The solar wind velocity is constant with no specific variation that can cause such a unique event.  However, multi-spacecraft observations by SOHO, DSCOVR, ACE, Cluster and MMS suggest the possibility of a very localized IMF structure. 

 

We thank magnetic stations of IMAGE, SuperMAG and INTERMAGNET network, and SOHO, DSCOVR, ACE, Cluster, DMSP and MMS team for providing data.

How to cite: Dimitrakoudis, S., Yamauchi, M., Magnar G., J., Philippe, E., Tohru, A., Tero, R., Ian R., M., Iannis, D., Per-Arne, L., and Christopher M., C.: Mysterious geomagnetic response to minor solar wind disturbance: Observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4032, https://doi.org/10.5194/egusphere-egu23-4032, 2023.

EGU23-5526 | ECS | Orals | ST2.3

Resolving Multiscale Magnetospheric and Radiation Belt Dynamics using Global MHD, Test Particle and Fokker Planck Simulations 

Ravindra Desai, Jonathan Eastwood, Sarah Glauert, Richard Horne, Joseph Eggington, Mike Heyns, Martin Archer, Harley Kelly, Lars Mejnertsen, and Jeremy Chittenden

The global magnetosphere represents an intricate and multi-scale system with dynamics occurring across scales ranging from metres to miles and milli-seconds to days. This represents a formidable challenge to understand, and differing plasma theories are typically applied to model the large-scale electromagnetic fields and the dynamics of the Van Allen radiation belts. This discretisation of plasma regimes, however, breaks down during extreme conditions when the magnetosphere becomes highly distorted and energetic particle dynamics vary rapidly across sub-drift timescales. To self-consistently model both short and long timescales, we combine global MHD and particle simulations with Fokker-Planck simulations to demonstrate how this presents a realistic and also necessary method to capture magnetospheric and radiation belt dynamics during severe geomagnetic storms. The global MHD simulations capture the large-scale modulations to the global magnetic and electric fields and the integrated particle simulations reveal intense acceleration processes during the compression phase and subsequent injections through the magnetotail. At relativistic energies, loss processes at low L shells are limited and the Fokker-Planck model reveals how newly accelerated radiation belt distributions evolve and persist over extended time periods. Modelling this flow of energy from the solar wind through to ring current and radiation belt populations, across both short and long time-scales, requires detailed observational constraints and we discuss how upcoming space missions will help us to holistically constrain energy transfers through our puzzling magnetosphere. 

How to cite: Desai, R., Eastwood, J., Glauert, S., Horne, R., Eggington, J., Heyns, M., Archer, M., Kelly, H., Mejnertsen, L., and Chittenden, J.: Resolving Multiscale Magnetospheric and Radiation Belt Dynamics using Global MHD, Test Particle and Fokker Planck Simulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5526, https://doi.org/10.5194/egusphere-egu23-5526, 2023.

EGU23-6104 | ECS | Orals | ST2.3 | Highlight

Soft X-ray Imaging of Earth’s Magnetopause under Different Solar Wind Conditions: Three-Dimensional Global Hybrid Simulations 

Jin Guo, Tianran Sun, San Lu, Quanming Lu, Yu Lin, Xueyi Wang, Kai Huang, and Rongsheng Wang

Earth’s magnetopause is a thin boundary separating the shocked solar wind plasma from the magnetospheric plasmas, and it is also the boundary of the solar wind energy transport to the magnetosphere. Soft X-ray imaging allows investigation of the large-scale magnetopause by providing a two-dimensional (2-D) global view from a satellite. However, it is challenging to derive information about the three-dimensional (3-D) magnetopause from a 2-D X-ray image. By performing 3-D global hybrid simulations, we obtain the soft X-ray imaging of Earth’s magnetopause under different solar wind conditions. The soft X-ray images observed by a hypothetical satellite are shown, and the location of the magnetopause, the cusps, and the magnetosheath are all identified in the X-ray images. Although there is a large amplitude fluctuation of the X-ray emissivity in the magnetosheath, the maximum X-ray intensity matches the tangent directions of the magnetopause well, which indicates that the magnetopause location can be identified from the 2-D X-ray images. Moreover, the magnetopause location can be identified with different positions of the satellite. We also find that solar wind conditions have little effect on the magnetopause identification. The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) mission will provide the X-ray images of the magnetopause for the first time, and our global hybrid simulation results can help better understand the 2-D X-ray images of the magnetopause from a 3-D perspective, with particle kinetic effects considered. 

How to cite: Guo, J., Sun, T., Lu, S., Lu, Q., Lin, Y., Wang, X., Huang, K., and Wang, R.: Soft X-ray Imaging of Earth’s Magnetopause under Different Solar Wind Conditions: Three-Dimensional Global Hybrid Simulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6104, https://doi.org/10.5194/egusphere-egu23-6104, 2023.

EGU23-6462 | ECS | Posters on site | ST2.3

Layered structure of near equatorial, ring current density and its ionospheric coupling: multi-spacecraft observations 

Xin Tan, Malcolm Dunlop, Yanyan Yang, Xiangcheng Dong, and Yingshuai Du

The Earth’s ring current forms a complex current system at the boundary of the inner magnetosphere. It is highly dynamic because of the interaction between the solar wind with the Earth's magnetosphere (the influence of space weather), while its morphology depends on the nature of the magnetospheric-ionospheric (M-I) coupling, generating field-aligned currents (FACs). Its behaviour can therefore have a huge impact on the terrestrial environment. According to Ampere's law, these currents can be directly measured by perturbations in the magnetic field using multi-spacecraft observation techniques. We have analyzed the magnetic field data from the four MMS spacecraft in their small-sale configuration to obtain the in-situ current density and have carried out statistical analysis from several years of data. The form of the current density distribution and its changing nature has been investigated. Our results show that the current density exhibits a three-dimensional layered structure in the ring current region. The significant westward current on the day side flows to higher magnetic latitudes and complete closure there rather than to the magnetic equator. There are some differences between geomagnetic quiet period and storm period on current density, but the basic spatial structure remains similar and compares well with previous space mission data. Comparison with Swarm data at low Earth altitudes, we found that the stratification is consistent with the distribution of the R2 field-aligned currents seen both adjacent to the ring current and at ionospheric altitudes (at Swarm). In addition, significant continuous eastward currents exist in some latitudes and some regions, indicating the complexity of the ring current. Some of them can be explained by the formation of banana currents.

How to cite: Tan, X., Dunlop, M., Yang, Y., Dong, X., and Du, Y.: Layered structure of near equatorial, ring current density and its ionospheric coupling: multi-spacecraft observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6462, https://doi.org/10.5194/egusphere-egu23-6462, 2023.

EGU23-6613 | ECS | Posters on site | ST2.3

Formation and identification of Kelvin-Helmholtz generated vortices at Earths magnetopause: Insight from adapting hydrodynamic techniques for MHD 

Harley Kelly, Martin Archer, Joseph Eggington, Mike Heyns, David Southwood, Ravindra Desai, Jonathan Eastwood, Lars Mejnertsen, and Jeremy Chittenden

The Kelvin-Helmholtz Instability (KHI) plays a significant role in the viscous-like mass, momentum, and energy transfer from the solar wind into the magnetosphere through both vortical and wave dynamics. To confidently study and compare the effects of these dynamics, we must formally define a vortex. Previously, a definition did not exist for the magnetohydrodynamic (MHD) regime. Consequently, we have developed a novel vortex definition (the `λMHD definition’) for MHD flows. This is based on adapting well-used hydrodynamic techniques (the λ2 family of methods) that defines a vortex as a local minimum in an adapted pressure field. We derive the MHD suitable adapted pressure field from the ideal MHD Cauchy-Momentum equation, and find that it is composed of four components. The first three components represent the hydrodynamic properties of rotational momentum flow, density inhomogeneity, and fluid compressibility respectively. The final component makes the λMHD definition unique from hydrodynamics as it represents the rotational component of the B Lorentz force which is found using a Helmholtz decomposition. We use the Gorgon global 3-Dimensional MHD code to validate the λMHD vortex definition within a northward IMF simulation run exhibiting KHI-driven waves at the magnetopause flanks. Comparison of λMHD with existing hydrodynamic definitions shows good correlations and skill scores, particularly with the more advanced methods. Our analysis also reveals that the rotational momentum flow term dominates at the magnetopause. The other components provide typically small corrections to this. We have found that at the magnetopause, compressibility generally acts in opposition to the existence of a pressure minimum and thus a vortex. Alternatively, inhomogeneity and the rotational component of the Lorentz force generally act to support the pressure minimum. We explore potential physical reasons for these results and discuss potential applications of this method to further simulation and spacecraft observations.

How to cite: Kelly, H., Archer, M., Eggington, J., Heyns, M., Southwood, D., Desai, R., Eastwood, J., Mejnertsen, L., and Chittenden, J.: Formation and identification of Kelvin-Helmholtz generated vortices at Earths magnetopause: Insight from adapting hydrodynamic techniques for MHD, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6613, https://doi.org/10.5194/egusphere-egu23-6613, 2023.

EGU23-6680 | ECS | Posters on site | ST2.3

Determination of pitch-angle diffusion coefficient from bi-Maxwellian velocity distribution functions 

Maxime Dubart, Markus Battarbee, Urs Ganse, Adnane Osmane, Felix Spanier, Markku Alho, Giulia Cozzani, Maarja Bussov, Konstantinos Horaites, Yann Pfau-Kempf, Jonas Suni, Vertti Tarvus, Lucile Turc, Ivan Zaitsev, Hongyang Zhou, and Minna Palmroth

Pitch-angle diffusion is one of the main processes of isotropisation of ions in the Earth's magnetosheath. It results from the proton cyclotron and mirror instabilities, arising from temperature anisotropy in the magnetosheath, and is governed by the pitch-angle diffusion coefficient Dμμ. We have previously developed a sub-grid model to describe pitch-angle diffusion in global-hybrid Vlasov simulations when coarse spatial grid resolution leads to a lack of diffusion. In this study, we present an analytical solution for a pitch-angle diffusion coefficient derived from bi-Maxwellian velocity distribution functions in order to apply this solution to the sub-grid model. This will allow us to model accurately the isotropisation of the distribution functions and to reduce the temperature anisotropy of the plasma while saving computational resources. 

How to cite: Dubart, M., Battarbee, M., Ganse, U., Osmane, A., Spanier, F., Alho, M., Cozzani, G., Bussov, M., Horaites, K., Pfau-Kempf, Y., Suni, J., Tarvus, V., Turc, L., Zaitsev, I., Zhou, H., and Palmroth, M.: Determination of pitch-angle diffusion coefficient from bi-Maxwellian velocity distribution functions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6680, https://doi.org/10.5194/egusphere-egu23-6680, 2023.

EGU23-6875 | ECS | Posters on site | ST2.3

Nightside dynamics influence on the dayside ionospheric current 

Reham Elhawary, Karl Magnus Laundal, Jone Peter Reistad, Michael Madelaire, and Anders Ohma
The main driver of the ionospheric dayside dynamics is the interaction between the interplanetary magnetic field (IMF) and the Earth’s magnetic field near the dayside magnetopause, while magnetotail activities control the nightside ionospheric dynamics. In spite of that, our knowledge about the influence of magnetotail activity on the dayside ionospheric dynamics and vice versa is limited. We investigate the nightside influence on the dayside ionospheric current by performing superposed epoch analyses of ground magnetic field data for northward IMF substorms. Such substorms encounter minimal influence of the dayside reconnection, granting an opportunity to isolate the effects of magnetotail activity on the dayside current system. Our analyses indicate that as nightside activity elevates, the dayside ionospheric current changes. We also find that lobe reconnection is weaker before substorm onset than what is expected for northward IMF conditions and then increases after onset, possibly due to reconfiguration of the magnetosphere. We present three possible mechanisms that can explain our observations.
 

How to cite: Elhawary, R., Laundal, K. M., Reistad, J. P., Madelaire, M., and Ohma, A.: Nightside dynamics influence on the dayside ionospheric current, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6875, https://doi.org/10.5194/egusphere-egu23-6875, 2023.

EGU23-7165 | ECS | Posters on site | ST2.3

A semi-empirical model for magnetic storm dynamics 

Simone Benella, Giuseppe Consolini, Mirko Stumpo, and Tommaso Alberti

The near-Earth electromagnetic environment represents a far-from-equilibrium system. The magnetosphere exhibits nonstationary and nonlinear dynamics, especially during magnetic storms. For a broad class of complex phenomena, the dynamics can be interpreted in terms of a superposition of stochastic and deterministic components, occurring at different time scales. The main feature of a magnetic storm is the depression of the horizontal magnetic field component at low latitudes due to the enhancement of the ring current activity. In this work we use the SYM-H geomagnetic index, which is meant for monitoring the global variation of the horizontal component of the Earth’s magnetic field along the equator. The aim of this work is to model the SYM-H dynamics via stochastic differential equations whose parameters are properly retained from data. As a first step we investigate the Markovian character of SYM-H, which accurately satisfies this requirement with 1-min time resolution. This allows us to model the SYM-H dynamics via Kramers–Moyal analysis. We give evidence that a purely diffusive process is not representative of the observed dynamics and then a model based on jump-diffusion processes must be taken into account in order to reproduce correctly the dynamical features of the SYM-H index. In light of recent findings on auroral electrojet dynamics, high-latitude magnetospheric activity also shows a jump-diffusion character on small time scales. A discussion of the future perspective of a comprehensive model of both auroral activity and ring current dynamics based on the multivariate Kramers-Moyal analysis is addressed.

* This research has been carried out in the framework of the CAESAR 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 prototype of scientific data centre for Space Weather.

How to cite: Benella, S., Consolini, G., Stumpo, M., and Alberti, T.: A semi-empirical model for magnetic storm dynamics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7165, https://doi.org/10.5194/egusphere-egu23-7165, 2023.

EGU23-7204 | Orals | ST2.3

Magnetopause properties from global MHD numerical simulations, local Vlasov equilibrium models and in-situ observations 

Marius M. Echim, Gabriel Voitcu, Costel Munteanu, and Eliza Teodorescu

We derive the properties of the terrestrial magnetopause (MP) from two modelling approaches, one global-fluid/MHD, the other local-kinetic,  as well as from in-situ data analysis. We use global MHD simulations of the Earth’s magnetosphere (publicly available from NASA-CCMC) and local Vlasov equilibrium models (based on kinetic models for tangential discontinuities) to extract spatial profiles of the plasma and field across the Earth’s magnetopause. We use data from MMS spacecraft to probe in-situ the properties of the magnetopause. The experimental data also serve as a reference for comparing/validating the numerical simulations. The global MHD simulations use initial conditions in the solar wind extracted from OMNI database at time epoch when MMS crossed the magnetopause. The kinetic Vlasov model uses boundary conditions derived from the same in-situ MMS measurements upstream/downstream the MP. We find  the global MHD simulations generally locate the MP at distances of one Earth radius farther from the position observed by MMS. We also find an overestimation of  the  thickness of the MP by one order of magnitude, as well as of the plasma density in the vicinity of the magnetopause. The MP spatial scale derived from local Vlasov equilibrium is consistent with observations for three transition profiles (magnetic field, plasma density, plasma bulk velocity). The overestimation of the density in Vlasov equilibrium is reduced compared with global MHD solutions. We discuss our results in the context of future SMILE mission campaigns for observing the Earth’s magnetopause.

How to cite: Echim, M. M., Voitcu, G., Munteanu, C., and Teodorescu, E.: Magnetopause properties from global MHD numerical simulations, local Vlasov equilibrium models and in-situ observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7204, https://doi.org/10.5194/egusphere-egu23-7204, 2023.

EGU23-7399 | ECS | Orals | ST2.3

Global environmental constraints on magnetic reconnection at the magnetopause from in situ measurements 

Bayane Michotte de Welle, Nicolas Aunai, Benoit Lavraud, Vincent Génot, and Roch Smets

The location of magnetic reconnection at the Earth's magnetopause is a longstanding question in the field of magnetospheric physics. Various models  (Alexeev et al. 1998, Borovsky 2013, Trattner et al. 2007, etc) predicting the position of the X-line have been proposed. These models often rely on quantities whose global spatial distributions at the magnetopause are typically obtained through numerical simulations. In this study, we attempt to reconstruct these global distributions using only in-situ measurements. To do this, we have used statistical learning to automatically select in-situ data from four missions (Cluster, Doublestar, THEMIS, MMS). The 3D reconstruction of the magnetic field draping in the dayside magnetosheath (Michotte de Welle et al. 2022) reveals significant differences with the model of Kobel et Fluckiger 1994 for a certain range of IMF orientations. As this magnetostatic model is frequently used to predict magnetic shear at the magnetopause, we will examine the implications of these differences on the X-lines maximizing this quantity (Trattner et al. 2007). We will also extend this discussion to other relevant quantities such as current density and the Cassak-Shay reconnection rate, which can also be accessed using in-situ measurements.

How to cite: Michotte de Welle, B., Aunai, N., Lavraud, B., Génot, V., and Smets, R.: Global environmental constraints on magnetic reconnection at the magnetopause from in situ measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7399, https://doi.org/10.5194/egusphere-egu23-7399, 2023.

EGU23-7628 | ECS | Posters on site | ST2.3

Untangling the Interhemispheric Response to Solar Wind Drivers through Numerical Experiments 

Dogacan Ozturk, Hyomin Kim, Zhonghua Xu, and Ilya Kuzichev

With the increased availability of ground magnetic field measurements from the Northern and Southern hemispheres at higher latitudes, further insight could be gained into how the physical processes coupling magnetosphere and ionosphere vary with solar wind forcing. In this study, we report a solar wind dynamic pressure enhancement followed by an interplanetary magnetic field clock angle change on February 13, 2014. We use measurements from East Antarctica and West Greenland regions to investigate when and where the magnetic field signatures differ. Finally, we use the University of Michigan Space Weather Framework (SWMF) to conduct numerical simulations to explain the differences in the interhemispheric responses to the changes in solar wind dynamic pressure enhancement and IMF clock angle together and separately. 

 

This work is supported by NASA LWS Program and makes use of the NASA High-End Computing Capability.

How to cite: Ozturk, D., Kim, H., Xu, Z., and Kuzichev, I.: Untangling the Interhemispheric Response to Solar Wind Drivers through Numerical Experiments, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7628, https://doi.org/10.5194/egusphere-egu23-7628, 2023.

EGU23-8568 | ECS | Orals | ST2.3

Flapping of the magnetotail current sheet in a global 6D hybrid-Vlasov simulation. 

Ivan Zaitsev, Giulia Cozzani, Miro Palmu, Yann Pfau-Kempf, Urs Ganse, Markus Battarbee, Markku Alho, Hongyang Zhou, Maxime Grandin, Maxime Dubart, Jonas Suni, Maarja Bussov, Lucile Turc, Konstantinos Horaites, Konstantinos Papadakis, Evgenii Gordeev, Fasil Kebede, Vertti Tarvus, and Minna Palmroth

Flapping waves are large-scale oscillations of the Earth's magnetotail current layer propagating in a cross-tail direction. In the current study, we investigate the plasma sheet flapping waves observed in a global 6D hybrid-Vlasov simulation of the Earth’s magnetosphere obtained with the Vlasiator code. Applying the timing analysis for 4 virtual spacecraft located in the near tail around X=-14 Re (where Re=6371 km is the Earth radius), we find that the phase velocity of the waves is directed duskwards and has a magnitude comparable to the ion drift velocity in the current sheet centre. We analyse the spatio-temporal characteristics of the waves by the ad-hoc technique of current sheet extremum tracing and we find that the average period of the flapping waves is T~40 s, and the typical wavelength λ=1.6 Re. The necessity to develop a specific technique arises from the large inaccuracy of the timing analysis output for the different positions of the virtual spacecraft constellation. We clearly observe that the area of most intense growth of the flapping oscillations coincides with the vicinity of the ion diffusion region of magnetic reconnection. In order to clarify the origin of the flapping waves, we calculate the dispersion relation for the ion-kink instability, taking the parameters of different ion distributions observed nearby with the reconnection X-line at the different time steps. Notably, the ion distribution has a specific crescent-type shape revealing the meandering motion of ions in the reconnecting current sheet that we identify as ions carrying the non-adiabatic current which is required for the development of the current layer instabilities. The agreement between the predicted values of the frequency and wave vectors and those observed in the simulation gives us evidence that flapping waves in the global hybrid-Vlasov simulation arise due to the development of the ion kink instability in the reconnecting current layer.

How to cite: Zaitsev, I., Cozzani, G., Palmu, M., Pfau-Kempf, Y., Ganse, U., Battarbee, M., Alho, M., Zhou, H., Grandin, M., Dubart, M., Suni, J., Bussov, M., Turc, L., Horaites, K., Papadakis, K., Gordeev, E., Kebede, F., Tarvus, V., and Palmroth, M.: Flapping of the magnetotail current sheet in a global 6D hybrid-Vlasov simulation., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8568, https://doi.org/10.5194/egusphere-egu23-8568, 2023.

EGU23-8593 | Orals | ST2.3 | Highlight

How does the Ionosphere Drive the Magnetospheric Processes? 

Tuija Pulkkinen, Shannon Hill, Austin Brenner, Qusai Al Shidi, and Gabor Toth

Solar wind – magnetosphere – ionosphere interactions are often interpreted as the solar wind flow and interplanetary magnetic field driving the dynamic processes in the magnetosphere – ionosphere system. However, the atmosphere and the ionosphere host independent dynamic processes, which also influence the magnetospheric dynamics in as yet unquantified ways. In this study, we assess the ability of the global MHD simulations to predict geomagnetic indices, and the role the ionospheric conductance plays in the magnetosphere – ionosphere coupling processes. Specifically, we use the University of Michigan Space Weather Modeling Framework and its Geospace configuration in two different setups: one using the standard Ridley Ionosphere Model (setup similar to that operationally used by the NOAA Space Weather Prediction Center) and another using the  Conductance Model for Extreme Events (CMEE). Comparing the model results for subsolar magnetopause position, AL, Dst, and cross-polar cap potential (CPCP) indices with observed quantities allows us to assess the role of the ionospheric conductance model as well as the overall level of uncertainty within the model as function of the driving intensity. The comparisons are done using a large set of over 80 simulations of geomagnetic storms using both setups.

How to cite: Pulkkinen, T., Hill, S., Brenner, A., Al Shidi, Q., and Toth, G.: How does the Ionosphere Drive the Magnetospheric Processes?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8593, https://doi.org/10.5194/egusphere-egu23-8593, 2023.

EGU23-9233 | ECS | Posters on site | ST2.3

Statistics of Magnetospheric Sawtooth Oscillations 

Connor DiMarco, Tuija Pulkkinen, Sanjay Kumar, and Matti Ala-Lahti

Magnetospheric sawtooth events (STE) are periodic oscillations in Earth’s magnetic field and energetic particle fluxes, typically occurring during geomagnetic storms. While previous studies have helped to provide information about the characteristics of STEs and the conditions that lead to the onset of these events, very little research has been done in the past 10 years documenting STEs, and analyzing the inner magnetosphere magnetic configuration during sawtooth events. This information can help understand how storms and substorms affect ionosphere-thermosphere convection, and how low-latitude ionospheric disturbances are generated during substorms. This project uses observations from magnetospheric missions and ground-based magnetometer networks to study the sawtooth event processes. Using magnetic field measurements GOES and the auroral electrojet indices, we are able to identify and catalog sawtooth events. We present our methods for identifying sawtooth events and preliminary statistics of the event characteristics. Then using magnetic field measurements from the THEMIS, RBSP, and MMS missions, we will study the evolution of the ring current and its latitudinal and longitudinal variations during STEs. We will also assess the abilities of the empirical Tsyganenko field models to reproduce the magnetospheric conditions during sawtooth events.

How to cite: DiMarco, C., Pulkkinen, T., Kumar, S., and Ala-Lahti, M.: Statistics of Magnetospheric Sawtooth Oscillations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9233, https://doi.org/10.5194/egusphere-egu23-9233, 2023.

EGU23-9280 | Posters on site | ST2.3

Conformally-mapped planetary magnetosheath model 

Yasuhito Narita, Simon Toepfer, and Daniel Schmid

A high-precision model of steady-state plasma flow and magnetic field in the planetary magnetosheath region is proposed by introducing the concept of conformal mapping and transforming the Kobel-Flueckiger scalar potential (the exact solution of Laplace equation) from the parabolic boundaries (bow shock and magnetopause) into arbitrary shape of boundaries. While the statistically-confirmed bow shock and magnetopause models can often be extended to the complex plane by analytic contiuation, construction of conformal mapping in a general magnetosheath case turns out be a mathematical challenge. The reason for this is that the analytic continuation of the bow shock shape does not necessarily meet the analytic contination of the magnetopause shape in general. We overcome this problem and construct a numerical conformal mapping method for the magnetosheath with arbitrary bow shock and magnetopause shapes by (1) modeling shell-like envelopes that smoothly change vary between the two boundaries (the v-variables), (2) imposing the orthogonality condition to find normal directions to the envelopes (the u-variables), and (3) applying the u and v variables to the Kobel-Flueckiger potential. Our conformal mapping method serves as a reference model of magnetosheath, which is numerically inexpensive and is easily implemented. Analysis of in-situ measurement data and numerical simulations of the planetary magnetosheath region will significantly benefit from the conformal mapping method. Moreover, our method can be used to derive the upstream conditions (flow speed and magnetic field) using the magnetosheath data.

How to cite: Narita, Y., Toepfer, S., and Schmid, D.: Conformally-mapped planetary magnetosheath model, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9280, https://doi.org/10.5194/egusphere-egu23-9280, 2023.

EGU23-9418 | Orals | ST2.3 | Highlight

Cross-Scale Magnetotail Convection: from Individual Properties and Impacts to Systems Understanding 

Aleksandr Ukhorskiy, Robyn Millan, Viacheslav Merkin, Kareem Sorathia, Matina Gkioulidou, and Anthony Sciola

Coupling of the solar wind and Earth’s magnetosphere is strongest during intervals of the southward interplanetary magnetic field (IMF), when magnetic reconnection at the subsolar magnetopause, with subsequent reconnection in the distant magnetotail, sets off a global convection cycle that transfers magnetic flux from the dayside into the magnetotail and then back to the dayside magnetosphere. Plasma sheet convection from the distant reconnection line to the inner magnetosphere exhibits a wide range of coupled multi-scale processes. Non-monotonic features in the plasma sheet magnetic terrain, such as minima, tailward gradients, or bumps in the northward component of the magnetic field lead to instabilities and  energy from transfer from large scale (~100 Earth radii) to mesoscale (~Earth radii) structures and earthward plasma flows. These in turn generate a wide range of kinetic scale (~100 km) phenomena which energize particles beyond 100 keV and produce bursts of particle precipitation into the atmosphere. In this paper we explore the properties and the role of mesoscale convection in the transport and acceleration of energetic electrons and ions from the magnetotail to the inner magnetosphere, from direct injections of particles into the radiation belt and the ring current, to generation of velocity instabilities that provide the pathway for the energy cascade from global to kinetic processes. We employ test-particle simulations in our Conservative Hamiltonian Integrator of Magnetospheric Particles (CHIMP) one way coupled to a high-resolution magnetohydrodynamic (MHD) simulations of plasma convection in the magnetotail. For the latter we use the Grid Agnostic MHD for Extended Research Applications (GAMERA) global magnetospheric model. We then use new modeling results and understanding of individual properties and impacts on plasmasheet dynamics to discuss Heliophysics Systems Observatory capabilities that would enable a system-wide view of cross-scale convection in Earth’s magnetotail. 

How to cite: Ukhorskiy, A., Millan, R., Merkin, V., Sorathia, K., Gkioulidou, M., and Sciola, A.: Cross-Scale Magnetotail Convection: from Individual Properties and Impacts to Systems Understanding, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9418, https://doi.org/10.5194/egusphere-egu23-9418, 2023.

EGU23-9761 | ECS | Posters on site | ST2.3

Estimating the Subsolar Magnetopause Position from Soft X-ray Images using Lowpass Image Filter 

Hyangpyo Kim, Hyunju Connor, Jaewoong Jung, Brian Walsh, and David Sibeck

The Lunar Environment Heliospheric X-ray Imager (LEXI, lunar flatform) and Solar wind-Magnetosphere-Ionosphere Link Explorer (SMILE, high apogee Earth-orbiter) will take photos of the Earth’s dayside magnetopause and cusps in soft X-rays after their respective launch in 2024 and 2025 for understanding global magnetic reconnection modes under varying solar wind conditions. To support successful science closure, it is critical to develop techniques to extract magnetopause position from observed soft X-ray images. In this presentation, we introduce a new method that derives subsolar magnetopause position (SMP) as a function of a satellite location and a look direction that gives peak soft X-ray emission. Two assumptions are used in this method: 1. The look direction of maximum soft X-ray emission is the tangent to magnetopause, 2. the magnetopause near a subsolar point is nearly spherical and thus the SMP is equal to the radius of magnetopause curvature. We test this magnetopause tracing method by using the anticipated LEXI soft X-ray images under various solar wind conditions. First, we simulate synthetic soft X-ray images observed from various LEXI locations using the OpenGGCM global magnetosphere MHD model. Galactic background, particle background, and Poisson noises are considered in these images. Then, we apply a lowpass filter to the synthetic LEXI images for removing noises and obtaining accurate look angles of soft X-ray peaks. From filtered images, we calculate SMPs for various LEXI locations and solar wind fluxes, and estimate its accuracy by using the SMPs of OpenGGCM as ground truth. Our method estimates SMPs with an accuracy of <0.3RE and this accuracy improves as the solar wind density increases.

How to cite: Kim, H., Connor, H., Jung, J., Walsh, B., and Sibeck, D.: Estimating the Subsolar Magnetopause Position from Soft X-ray Images using Lowpass Image Filter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9761, https://doi.org/10.5194/egusphere-egu23-9761, 2023.

EGU23-9888 | Orals | ST2.3

Global Shock Dynamic and Ion Acceleration at Filamentary Structures Downstream of the Earth’ s Bow Shock. 

Harald Kucharek, Steven J Schwartz, Imogen Gingell, Charles Farrugia, and Karlheinz J Trattner

At the Earth’s bow shock, most of the solar wind’s kinetic energy is partitioned into wave energy, particle acceleration, and heating. Very recent publications provide strong evidence that current sheets at the shock ramp region and downstream may participate in the thermalization of the solar wind plasma. Their occurrence varies from single to multiple current sheets as well as filamentary structures.

We studied multiple bow shock crossings by the MMS spacecraft with its sophisticated instrumentation, characterizing and quantifying the occurrence of filamentary structures, current sheets, the associated magnetic field wave turbulence, and ion acceleration downstream of the shock. At some traversals the shock location is changing due to variable upstream solar wind conditions. During increasing Mach number/dynamic pressure we observe higher wave activity and broader distribution functions with suprathermal tails. Much less suprathermal ions downstream of the shock are observed at shock crossings during decreasing upstream Mach numbers. These MMS observation indicate that current sheets and field gradients are associated with ion acceleration. The associated turbulence is likely a mediator for energy partition. With increasing Mach numbers, the bow shock moves away from the Sun and compresses the magnetosheath that would favour reconnection of currents sheets, stronger electric field gradients and thus ion acceleration. At periods of decreasing upstream Mach numbers, the bow shock moves towards the Sun, becomes blunter, and the sheath region relaxes, making reconnecting current sheets less likely and smoothens field gradients resulting in less acceleration. Other possible acceleration mechanisms will also be discussed in the context of this presentation.

How to cite: Kucharek, H., Schwartz, S. J., Gingell, I., Farrugia, C., and Trattner, K. J.: Global Shock Dynamic and Ion Acceleration at Filamentary Structures Downstream of the Earth’ s Bow Shock., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9888, https://doi.org/10.5194/egusphere-egu23-9888, 2023.

EGU23-9931 | ECS | Orals | ST2.3

Detailed look at energy dynamics in Earth’s magnetosphere using simulation 

Austin Brenner, Tuija Pulkkinen, and Qusai Al Shidi

Energy transport into and throughout Earth's magnetosphere has direct consequences for human infrastructure in orbit and on the planets surface but studying the entire system in a comprehensive and quantifiable way has many challenges. In this work we use the Space Weather Modeling Framework (SWMF) in the Geospace configuration with the addition of the Conductance Model for Extreme Events (CMEE) to simulate a real storm event and take a thorough look at the energy content within regions of the magnetosphere. The magnetosphere outer boundary is defined using techniques published in Brenner et al. 2021 and is represented in the simulation domain as an iso-surface. Additional boundaries between the lobes and the closed field line plasma sheet are then determined in order to study the transport of energy between the different plasma regimes from the magnetosheath to the inner magnetosphere. The results are shown as time-series of integrated energy content within each region volume, and integrated energy flux between the regional interfaces. These volume energies and surface fluxes are compared with input solar wind conditions, storm phases, and empirical solar wind - magnetosphere coupling functions. Finally, the results are quantitatively assessed in terms of statistical parameters of the integrated quantities during each storm phase as well as statistical relationships such as correlation coefficients between energy from the sheath to the lobes and lobes to the closed field line region. 

How to cite: Brenner, A., Pulkkinen, T., and Al Shidi, Q.: Detailed look at energy dynamics in Earth’s magnetosphere using simulation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9931, https://doi.org/10.5194/egusphere-egu23-9931, 2023.

EGU23-10258 | ECS | Posters virtual | ST2.3 | Highlight

Earth’s magnetosphere dynamics during “forced breathing” due to solar wind periodic density structures 

Simone Di Matteo, Larry Kepko, Nicholeen Viall, Aaron Breneman, Alexa Halford, and Umberto Villante

In the solar wind density, we often observe periodic fluctuations on time scales ranging from a few minutes to a few hours which we refer to as Periodic Density Structures (PDSs). The PDSs belong to the class of “meso-scale structures” with radial length scales greater than or equal to the size of the Earth’s dayside magnetosphere. The periodic character of these transients (≈0.2-4.0 mHz) can determine periodic compressional fluctuations of the Earth’s magnetic field at similar frequencies (“forced breathing” mode). The corresponding time scales overlap with the frequency range of Pc5 Ultra Low Frequency (ULF) waves (≈1.7-6.7 mHz). The compressional “forced breathing” fluctuations are often global and impact the entire Earth’s magnetosphere system/dynamics.  Using a recently developed spectral analysis approach applied to magnetic field observations at satellites and ground stations, we were able to differentiate directly driven magnetic field oscillations from Pc5 ULF waves triggered by other sources. Here, we discuss clear examples of such a directly driven process also showing effects on radiation belt electron dynamics and loss.

How to cite: Di Matteo, S., Kepko, L., Viall, N., Breneman, A., Halford, A., and Villante, U.: Earth’s magnetosphere dynamics during “forced breathing” due to solar wind periodic density structures, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10258, https://doi.org/10.5194/egusphere-egu23-10258, 2023.

EGU23-10542 | ECS | Posters on site | ST2.3

Modeling of the Subsolar Magnetopause Motion Under Interplanetary Magnetic Field Southward Turning 

Qiuyu Xu, BinBin Tang, Tianran Sun, Xiaoxin Zhang, Fei Wei, Xiaocheng Guo, and Chi Wang

In this study, a new analytical model to describe the time-dependent subsolar magnetopause motion under interplanetary magnetic field (IMF) southward turning has been developed. This model, based on the scenario of magnetopause erosion due to magnetic reconnection, can be approximated by both linear and non-linear functions. The linear function is simplified under the assumption of constant magnetopause erosion under southward IMF, and the non-linear function is derived by assuming that the magnetopause erosion decays exponentially. In the limit of a short time, the non-linear function is essentially the same as the linear function. By comparing with global MHD simulations, the linear function performs well within the first ten minutes, and the error then increases with time. The non-linear function describes the magnetopause motion more accurately with respect to, and consistent with simulations for a time interval of $\sim 40$ minutes. This model has also been successfully applied to data-driven simulations of the 17 March 2015 geomagnetic storm event, suggesting the possible applicability of this model in reality. 

How to cite: Xu, Q., Tang, B., Sun, T., Zhang, X., Wei, F., Guo, X., and Wang, C.: Modeling of the Subsolar Magnetopause Motion Under Interplanetary Magnetic Field Southward Turning, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10542, https://doi.org/10.5194/egusphere-egu23-10542, 2023.

Increases in the solar wind dynamic pressure compress the magnetosphere, enhance magnetic field strengths and push the magnetopause inward.  Enhanced reconnection on the magnetopause, as might be expected during southward IMF conditions, launches rarefaction waves into the magnetosphere, decreases magnetic field strengths, and erodes the magnetopause inward.  Nightside magnetotail magnetic fields stretch tailward during erosion events and ultimately snap back to dipolar orientations at substorm onset.  The effects can be seen clearly in geosynchronous orbit.  We present a statistical survey of the effects of magnetopause motion and substorm stretching and dipolarization on magnetic fields deep inside both the dayside and nightside magnetosphere using observations from NOAA’s GOES satellites.

How to cite: Hsieh, S.-Y. and Sibeck, D.: The Effects of Magnetopause Motion and Substorm Stretching and Dipolarization on Magnetic Fields in the Inner Magnetosphere , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10776, https://doi.org/10.5194/egusphere-egu23-10776, 2023.

EGU23-11389 | ECS | Posters on site | ST2.3

The Magnetospheric Source of Theta Aurora Include Dayside and Nightside Multiple Reconnection Sites: SWMF Geospace Simulation Results 

Shannon Hill, Tuija Pulkkinen, Austin Brenner, Qusai Al Shidi, Agnit Mukhopadhyay, Anita Kullen, Harald Frey, Shasha Zou, and Michael Liemohn

We present simulation results of a transpolar auroral arc event that show the arc formation occurs on both open and closed field lines and is sourced from both dayside and nightside magnetospheric reconnection. The dayside and nightside precipitation sources magnetically connect across the polar cap in a flow channel to create the transpolar arc structure. We simulate the 15 May 2005 transpolar arc event observed by the IMAGE satellite with the University of Michigan Space Weather Modeling Framework (SWMF) Geospace configuration. We compare the IMAGE observations to the simulation produced ionospheric Joule heating to identify the transpolar arc features captured by the model. The features exist within an anti-sunward flow structure and coincide with the location of the R1/R2 current reversal. We map the magnetic field lines from the arc features to the magnetosphere, revealing both dayside and nightside source regions. We use four-field junction analysis to determine that the source regions are within potential simulation reconnection sites. We simulate other transpolar auroral arcs to assess the generality of our results.

How to cite: Hill, S., Pulkkinen, T., Brenner, A., Al Shidi, Q., Mukhopadhyay, A., Kullen, A., Frey, H., Zou, S., and Liemohn, M.: The Magnetospheric Source of Theta Aurora Include Dayside and Nightside Multiple Reconnection Sites: SWMF Geospace Simulation Results, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11389, https://doi.org/10.5194/egusphere-egu23-11389, 2023.

EGU23-11423 | Orals | ST2.3 | Highlight

What if… we could observe the aurora in both hemispheres. 

Alexa Halford, Mike Liemohn, Dan Welling, and Aaron Ridley and the MAAX Science Team

The aurora is a beautiful manifestation and tracer of the drivers and processes active in the interconnected geospace system. For decades we have stretched to find ways to use the aurora to gain a global view of our geospace system, most being ground-based. Ground-based measurements provide longevity in the northern hemisphere but are impacted by terrestrial weather and constrained by where there is accessible land. For a short few months, the Polar and IMAGE satellites periodically provided simultaneous images of the northern and southern aurora. From these few advantageous conjugate auroral zone observations, it was discovered that there are substantial asymmetries between the northern and southern hemispheres. Conjugate auroral features were found to exhibit different morphologies and are sometimes shifted by 10-20 ̊ in longitude. We have tried to gain insight through statistical studies of the aurora… but what questions could be answered if we observed the aurora in both hemispheres simultaneously? It has been 20+ years since NASA launched a space-based mission to image the aurora. Here we look to discuss a new mission idea focused on providing this genuinely global view, opening up pathways to answer large-scale system science questions. 

How to cite: Halford, A., Liemohn, M., Welling, D., and Ridley, A. and the MAAX Science Team: What if… we could observe the aurora in both hemispheres., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11423, https://doi.org/10.5194/egusphere-egu23-11423, 2023.

EGU23-11674 | Posters on site | ST2.3

Auroral dripping and its possible magnetospheric source 

Wenrui Wang, Jian Yang, and Fei Zhang

We have recently discovered a new auroral structure called "auroral dripping" with ground-based and magnetospheric conjugated observations. They are frequent drippings from higher latitudes toward the equator, with a duration of 10-20 minutes. Magnetospheric observations show increases in particle flux and magnetic field simultaneously. With the keograms and ewograms, we find that the auroral drippings are different from other periodic structures in the motion and the temporal periodicity. To investigate the possible magnetospheric source of this structure, we simulate the entire process with the Rice Convection Model coupled with an MHD code (RCM-MHD). After long-lasting low-entropy plasma is supplied from the tailward boundary, frequent drippings and the accompanying oscillations in the near-Earth plasma sheet are reproduced. Our preliminary results suggest that the continuous plasma injection is considered to be possible magnetospheric source of the auroral dripping.

How to cite: Wang, W., Yang, J., and Zhang, F.: Auroral dripping and its possible magnetospheric source, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11674, https://doi.org/10.5194/egusphere-egu23-11674, 2023.

EGU23-11679 | ECS | Orals | ST2.3 | Highlight

Expansion and Contraction of the Auroral Oval Area 

Anders Ohma, Karl Magnus Laundal, Jone Peter Reistad, Spencer Mark Hatch, Michael Madelaire, Sara Gasparini, Margot Decotte, and Simon James Walker

The aurora is a visible manifestation of Earth’s coupling to near-Earth space. The emitted light is produced by charged particles that precipitate into the upper atmosphere. These particles are usually located on closed magnetic field lines that connect directly between the northern and southern hemisphere. As a result, Earth’s aurora often appears in an oval shape surrounding the magnetic pole. Inside the oval, at high magnetic latitudes, is a region with open magnetic field lines that extend into the solar wind. This region of open magnetic flux is the polar cap and is a consequence of the Dungey cycle: Reconnection between the solar wind magnetic field and closed terrestrial field lines at the dayside magnetopause produces open field lines which are transported to the nightside where they are again closed by reconnection. A fundamental property of the magnetosphere-ionosphere system is that changes in the amount of open magnetic flux is equal to the net difference between the dayside and nightside reconnection rates. That is, the polar cap expands when dayside reconnection dominates and contracts when nightside reconnection dominates. This is known as the expanding/contracting polar cap paradigm, and has been studied extensively in the last few decades. The expansion and contraction of the aurora itself has received less attention. In this work, we use global auroral images to study the spatiotemporal evolution of the auroral oval. We investigate how the solar wind, open flux and auroral flux covary. Furthermore, we attempt to determine how well a pure fluid description of the auroral zone can explain the observed evolution.

How to cite: Ohma, A., Laundal, K. M., Reistad, J. P., Hatch, S. M., Madelaire, M., Gasparini, S., Decotte, M., and Walker, S. J.: Expansion and Contraction of the Auroral Oval Area, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11679, https://doi.org/10.5194/egusphere-egu23-11679, 2023.

EGU23-12353 | Posters on site | ST2.3 | Highlight

SMILE: a mission to image the solar wind-magnetosphere interaction 

C.-Philippe Escoubet, Graziella Branduardi-Raymont, and Chi Wang and the SMILE team

The interaction between the solar wind and the Earth's magnetosphere, and the geospace dynamics that result, 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 quantify the global effects of the drivers of such connections, including the conditions that prevail throughout geospace. 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 wind/magnetosheath plasma 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 at the beginning of 2025. SMILE science objectives as well as the latest scientific and technical developments jointly undertaken by ESA and CAS and the international instrument teams will be presented.

How to cite: Escoubet, C.-P., Branduardi-Raymont, G., and Wang, C. and the SMILE team: SMILE: a mission to image the solar wind-magnetosphere interaction, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12353, https://doi.org/10.5194/egusphere-egu23-12353, 2023.

EGU23-12515 | ECS | Posters on site | ST2.3

The effect of ionospheric conductance on reconnection estimates based on ionospheric observations 

Sara Gasparini, Spencer M. Hatch, Jone P. Reistad, Anders Ohma, and Karl M. Laundal

Ground magnetometer measurements are frequently used to study ionospheric electrodynamics. It is possible to relate and combine ground magnetometer measurements with ionospheric convection measurements through the  ionospheric Ohm’s law. It is therefore important to have knowledge of the auroral conductances in order to utilize both these sources of information together when describing the 2D ionospheric electrodynamics. However, auroral conductances are very difficult to evaluate. In this study we use a new data assimilation technique on an event study to investigate the effect of different methods to retrieve auroral conductances. We focus on the effect on estimates of nightside reconnection, based on ionospheric convection and optical observations of the open closed boundary. We show that different choices of conductance lead to differences in ionospheric convection velocities, and hence differences in estimates of the reconnection electric fields. 

How to cite: Gasparini, S., Hatch, S. M., Reistad, J. P., Ohma, A., and Laundal, K. M.: The effect of ionospheric conductance on reconnection estimates based on ionospheric observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12515, https://doi.org/10.5194/egusphere-egu23-12515, 2023.

EGU23-13116 | ECS | Posters on site | ST2.3

Curlometer technique and applications 

Xiangcheng Dong, Malcolm Dunlop, Chao Shen, Tieyan Wang, Patrick Robert, Jonathan Eastwood, Stein Haaland, Yanyan Yang, Xin Tan, Philippe Escoubet, Zhaojin Rong, Huishan Fu, and Johan De Keyser

We review the range of applications and use of the curlometer, initially developed to analyze electric current density using Cluster multi-spacecraft magnetic field data; but more recently adapted to other arrays of spacecraft flying in formation, such as MMS small-scale, 4-spacecraft configurations; THEMIS close constellations of 3-5 spacecraft, and Swarm 2-3 spacecraft configurations. The method (and associated methods based on spatial gradients) has been shown to be easily adaptable to other multi-point and multi-scale arrays. Although magnetic gradients require knowledge of spacecraft separations and the magnetic field, the structure of the electric current density (for example, its relative spatial scale), and any temporal evolution, limits measurement accuracy. Nevertheless, in many magnetospheric regions the curlometer is reliable (within certain limits), particularly under conditions of time stationarity, or with supporting information on morphology (for example, when the geometry of the large scale structure is expected). A number of large-scale regions have been investigated directly, such as: the cross-tail current sheet, ring current, the current layer at the magnetopause and field-aligned currents. In addition, the analysis can support investigations of transient and smaller scale current structures (e.g. reconnected flux tubes, boundary layer sub-structure, or dipolarisation fronts) and energy transfer processes. The method is able to provide estimates of single components of the vector current density, even if there are only two or three satellites flying in formation, within the current region, as can be the case when there is a highly irregular spacecraft configuration. The computation of magnetic field gradients and topology in general includes magnetic rotation analysis and various least squares approaches, as well as the curlometer, and indeed the combination with plasma measurements and the extension to larger arrays of spacecraft have recently been considered. We touch on these extensions and on new methodology accessing the properties of the underlying formulism.

How to cite: Dong, X., Dunlop, M., Shen, C., Wang, T., Robert, P., Eastwood, J., Haaland, S., Yang, Y., Tan, X., Escoubet, P., Rong, Z., Fu, H., and De Keyser, J.: Curlometer technique and applications, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13116, https://doi.org/10.5194/egusphere-egu23-13116, 2023.

EGU23-13581 | Posters on site | ST2.3

SciQLop:  a tool suite to facilitate multi-mission data browsing and analysis 

Alexis Jeandet, Nicolas Aunai, Vincent Génot, Patrick Boettcher, Benjamin Renard, Bayane Michotte de Welle, Nicolas André, Myriam Bouchemit, and Nicolas Dufourg

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 in development 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., Génot, V., Boettcher, P., Renard, B., Michotte de Welle, B., André, N., Bouchemit, M., and Dufourg, N.: SciQLop:  a tool suite to facilitate multi-mission data browsing and analysis, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13581, https://doi.org/10.5194/egusphere-egu23-13581, 2023.

EGU23-16068 | Orals | ST2.3 | Highlight

Magnetospheric Auroral Asymmetry eXplorer: observing the aurora to uncover how energy flows in space 

Michael Liemohn, Aaron Ridley, Daniel Welling, Alexa Halford, Thomas Immel, Hyunju Connor, Anna DeJong, Gerard Fasel, Christine Gabrielse, Katherine Garcia-Sage, Brian Harding, Elizabeth MacDonald, Tomoko Matsuo, Emma Spanswick, and Shasha Zou

The Magnetospheric Auroral Asymmetry Explorer (MAAX) mission makes a major leap forward in determining how magnetosphereionosphere electrodynamic coupling regulates multi-scale auroral energy flow through the near-Earth space environment. Recently proposed to NASA’s Heliophysics Small Explorer program, MAAX accomplishes this by: (1) Understanding how seasons and tilt of the magnetic field regulate energy flow from the solar wind through the system; (2) discovering how the formation, evolution, and interhemispheric asymmetries of nightside meso-scale auroral features are regulated by the auroral background conductance; (3) determining how the time-dependent magnetospheric energy flow controls multi-scale auroral dynamics. The solar wind energy enters the magnetosphere mainly through dayside reconnection and is stored in the magnetosphere, which later converts to plasma and neutral thermal and kinetic energies. Dynamic smaller-scale processes in the nightside magnetosphere map from the magnetosphere to the ionosphere, resulting in auroral structures that have fascinated people for millennia. 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 recent observations suggest this may not always be applicable. With auroral observations from one hemisphere, we can only understand some of the processes that control the flow of energy through the system. However, with observations in both with observations in both hemispheres we gain a deeper understanding into the dynamics of this integrated system. MAAX comprises two observatories in circular polar orbits at 20,850 km altitude for viewing of the auroral ovals in both hemispheres. Each observatory carries a single high-heritage UV imager to close the science objectives that operate poleward of +/-35° latitude. For the first year of the mission, the observatories are spaced at 90° to allow continuous coverage on one oval, then the other with a 6-hour duty cycle. This phase also allows for intervals in which both view the same hemisphere or both view the same longitude but different hemispheres. For the second year of the mission, the observatories are spaced at 180° to have simultaneous complete viewing of both the northern and southern auroral ovals with a 4.5 hr/1.5 hr on/off duty cycle. Discussed here is the science motivation of the mission concept and the numerical modeling trade studies to optimize the mission characteristics to achieve the proposed objectives.

How to cite: Liemohn, M., Ridley, A., Welling, D., Halford, A., Immel, T., Connor, H., DeJong, A., Fasel, G., Gabrielse, C., Garcia-Sage, K., Harding, B., MacDonald, E., Matsuo, T., Spanswick, E., and Zou, S.: Magnetospheric Auroral Asymmetry eXplorer: observing the aurora to uncover how energy flows in space, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16068, https://doi.org/10.5194/egusphere-egu23-16068, 2023.

EGU23-16454 | ECS | Orals | ST2.3 | Highlight

Magnetospheric Response to a Pressure Pulse in a Three-dimensional Hybrid-Vlasov Simulation 

Konstantinos Horaites and the Vlasiator Team

Vlasiator is a high-performance ion-kinetic code that is now conducting global 3D hybrid-Vlasov simulations of the outer magnetosphere.  We use Vlasiator to investigate the impact of a pressure pulse with southward-oriented magnetic field on the Earth's magnetosphere. The simulation driving parameters are comparable to conditions that have led to real geomagnetic storms. Our pressure pulse simulations reproduce many physical effects, namely the expansion of the auroral oval, the development of field-aligned currents, enhanced particle precipitation near the open/closed field line boundary, and compression of Earth's magnetopause. This demonstrates the effectiveness of the hybrid-Vlasov approach for moderate driving conditions. Our investigation of the time-dependent magnetopause compression motivates a generalization of the existing theory. Specifically, we find that accounting for the finite ramp time of the solar wind dynamic pressure improves the model's description of the magnetopause oscillations.

How to cite: Horaites, K. and the Vlasiator Team: Magnetospheric Response to a Pressure Pulse in a Three-dimensional Hybrid-Vlasov Simulation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16454, https://doi.org/10.5194/egusphere-egu23-16454, 2023.

EGU23-798 | ECS | Posters on site | ST2.4

Investigating the acceleration efficiency of VLF and ULF waves on different electron populations in the outer radiation belt through multi-point observations and modeling 

Afroditi Nasi, Christos Katsavrias, Sigiava Aminalragia-Giamini, Nour Dahmen, Antoine Brunet, Constantinos Papadimitriou, Ingmar Sandberg, Sébastien Bourdarie, Viviane Pierrard, Edith Botek, Fabien Darrouzet, Ondrej Santolik, Benjamin Grison, Ivana Kolmasova, David Pisa, Yoshizumi Miyoshi, Wen Li, Hugh Evans, and Ioannis A. Daglis and the Arase Team

During the second half of 2019, the Earth’s magnetosphere was impacted by a sequence of Corotating Interaction Regions (CIRs) during four consecutive solar rotations. Based on the solar wind properties, the CIRs can be divided in four groups, with the 3rd group, which arrived on August-September 2019, resulting in significant multi-MeV electron enhancements, up to ultra-relativistic energies of 9.9 MeV.

Each CIR group has a different effect on the outer radiation belt electron populations; we investigate them by exploiting combined measurements from the Van Allen Probes, THEMIS, and Arase satellites. We produce Phase Space Density (PSD) radial profiles and inspect their dependence on the values of the first and second adiabatic invariants (μ,K), ranging from seed to ultra-relativistic electrons and from near-equatorial to off equatorial mirroring populations, respectively.

Focusing on the 3rd CIR group, and in order to assess the relative contribution of radial diffusion and gyro-resonant acceleration, we perform numerical simulations of the radiation belt environment, combining several relevant models: EMERALD (NKUA), GEO model (NKUA), Salammbô (ONERA), VLF model (IAP), Plasmaspheric model (BIRA-IASB), FARWEST (ONERA). We further compare the temporal evolution of the simulated electron PSD with the above observations.

This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870437 for the SafeSpace project.

How to cite: Nasi, A., Katsavrias, C., Aminalragia-Giamini, S., Dahmen, N., Brunet, A., Papadimitriou, C., Sandberg, I., Bourdarie, S., Pierrard, V., Botek, E., Darrouzet, F., Santolik, O., Grison, B., Kolmasova, I., Pisa, D., Miyoshi, Y., Li, W., Evans, H., and Daglis, I. A. and the Arase Team: Investigating the acceleration efficiency of VLF and ULF waves on different electron populations in the outer radiation belt through multi-point observations and modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-798, https://doi.org/10.5194/egusphere-egu23-798, 2023.

Atmospheric precipitation of radiation belt electrons plays an important role in the magnetosphere-ionosphere-atmosphere coupling system, which can trigger chemical and electric effects in the upper atmosphere and meanwhile generate aurorae of various types. In the regime of the quasi-linear theory, it is commonly accepted that the population of trapped electrons is no smaller than the precipitated population. However, such a concept has been proved to break down due to the nonlinear wave-particle interactions, which can drive the superfast electron precipitation. Therefore, on basis of the long-term MEPED datasets of POES satellites, we perform a comprehensive analysis of the spatiotemporal characteristics and geomagnetic dependence of superfast radiation belt electron precipitation. Our results demonstrate that superfast atmospheric precipitation of energetic electrons occurs with a non-negligible percentage with respect to the overall electron precipitation observations, and has the geomagnetic dependence similar to that of whistler-mode chorus waves.

How to cite: Guo, D., Xiang, Z., and Ni, B.: A statistical study of superfast atmospheric precipitation of radiation belt electrons observed by POES satellites, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3069, https://doi.org/10.5194/egusphere-egu23-3069, 2023.

EGU23-3134 | ECS | Posters on site | ST2.4

Simultaneous observations of whistler mode waves by the DEMETER spacecraft and the Kannuslehto station 

Kristyna Drastichova, František Němec, Jyrki Manninen, and Michel Parrot

We use conjugate observations of magnetospheric whistler mode electromagnetic waves at frequencies up to 16 kHz to determine their typical spatial scales and propagation to the ground. For this purpose, we use data obtained by the DEMETER spacecraft at an altitude of about 700 km and by the ground-based Kannuslehto station in Finland. The overlap between the two data sets corresponds to more than 500 DEMETER half-orbits between November 2006 and March 2008. Two different approaches are used. First, specific wave events observed simultaneously by both the spacecraft and the ground station are analyzed in detail. Second, the correlations of the power spectral densities of measured signals are calculated as a function of the frequency and geomagnetic longitude/L-shell separation. These are used to determine typical longitudinal/L-shell correlation lengths and to discuss wave propagation to the ground.

How to cite: Drastichova, K., Němec, F., Manninen, J., and Parrot, M.: Simultaneous observations of whistler mode waves by the DEMETER spacecraft and the Kannuslehto station, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3134, https://doi.org/10.5194/egusphere-egu23-3134, 2023.

EGU23-3188 | Orals | ST2.4

Line radiation events: Properties, generation, and propagation 

Frantisek Nemec, Ondřej Santolík, Jyrki Manninen, George B. Hospodarsky, and William S. Kurth

Whistler-mode waves propagating in the Earth’s inner magnetosphere sometimes appear as a set of nearly constant frequency elements separated by a fixed frequency. Such events are typically called line radiation, and they can have two distinct origins. First, events with narrow spectral lines and the frequency spacing corresponding to the base power system frequency (50/100 or 60/120 Hz) are generated by electromagnetic radiation from electric power systems on the ground (power line harmonic radiation, PLHR). Second, waves with broader spectral lines, whose frequency spacing does not correspond to the power system frequency, are believed to be generated by plasma instabilities in the magnetosphere (magnetospheric line radiation, MLR).

Frequencies of line radiation events are typically on the order of a few kHz, while their frequency spacing is on the order of a hundred Hz. Relevant spacecraft observations at larger radial distances are thus very sparse due to the typically low frequency resolution of available measurements, not sufficient to distinguish the line structure. We use high-resolution multicomponent wave measurements performed by the EMFISIS instrument on board the Van Allen Probes during the burst mode to fill this observational gap. We systematically identify the line radiation events and analyze their occurrence and properties. Detailed wave propagation analysis allows us to reveal wave propagation throughout the magnetosphere. We further show that the frequency spacing of MLR events appears to be related to an electrostatic wave observed at the corresponding frequency (≈100 Hz). Finally, conjugate observations performed by the Kannuslehto station in Finland are used to estimate the spatial extent of the events.

How to cite: Nemec, F., Santolík, O., Manninen, J., Hospodarsky, G. B., and Kurth, W. S.: Line radiation events: Properties, generation, and propagation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3188, https://doi.org/10.5194/egusphere-egu23-3188, 2023.

Whistler-Mode Chorus (WMC) waves are an important contributor to the dynamics of the magnetosphere, not only for their prevalence in measured observations of near-Earth space but also for their dominant role in transporting energy and particles throughout it. It is therefore of key importance to space weather modelling that we understand how WMC waves are generated, how they subsequently evolve and how they interact with the particle populations that they transport. There are also fundamental physics question to answer as WMC waves display nonlinear phenomena rarely seen in other fields, including their ability to raise and lower their frequency repeatedly and rapidly leading to rising and falling tone waves respectively. Are the interactions between the wave and the particles driving such phenomena, and if so to what degree are they doing so?

 

In this talk, we revisit the nonlinear evolution of WMC waves from a theoretical perspective.  Wave-particle interactions are shown to be a key driver of the modulational instabilities that lead to element and subelement formation which are well represented by an extension of the well-known Nonlinear Schrodinger equation. Simulations of this yields power spectrum reminiscent of the rising and falling tone emissions observed in mission data from the Van Allen probes, THEMIS, MMS and Cluster and determines that that wave-particle interactions are the primary cause of this effect. As a result, this nonlinear theory indicates regimes in which these frequency sweeps can be enhanced or dampened, and suggests why the WMC band gap at half the gyrofrequency exists.

How to cite: Ratliff, D. and Allanson, O.: Nonlinear wave-particle interactions in Whistler-Mode Chorus waves: modulation as a route to rising and falling tones, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3375, https://doi.org/10.5194/egusphere-egu23-3375, 2023.

EGU23-3445 | Orals | ST2.4

Global modeling of the mesoscale buildup of the ring current and its role in magnetosphere-ionosphere coupling 

Kareem Sorathia, Adam Michael, Anthony Sciola, Shanshan Bao, Dong Lin, Slava Merkin, Sasha Ukhorskiy, Constanze Roedig, and Jeffrey Garretson

During geomagnetically active periods plasma is transported from the magnetotail into the inner magnetosphere to become the ring current. The transpot of plasma into the ring current occurs at different spatial and temporal scales, from global quasi-steady convection to bursty bulk flows (BBFs), with typical cross-tail extents of 1-3 Earth radii. During its enhancement, the ring current plays a critical role in magnetosphere-ionosphere coupling. Ring current ions build up plasma pressure in the inner magnetosphere and will drive field-aligned currents which must close in the ionosphere, while electrons will lead to diffuse precipitation and enhanced ionospheric conductance which shape the ionospheric path of current closure. Current closure in the ionosphere will couple to the thermospheric neutral population, via Joule heating, and alter the dynamics of the plasmasphere, via the penetration electric field in the inner magnetosphere. 

Understanding the relative role of convection at different spatial scales in both the buildup of the ring current and its broader effects on geospace coupling is an area of active interest and one of the core science questions of the Center for Geospace Storms. In this talk I will describe how addressing this question has informed the development of the Multiscale Atmosphere Geospace Environment (MAGE) model and highlight several recent modeling studies which illustrate the central role of mesoscale processes.

How to cite: Sorathia, K., Michael, A., Sciola, A., Bao, S., Lin, D., Merkin, S., Ukhorskiy, S., Roedig, C., and Garretson, J.: Global modeling of the mesoscale buildup of the ring current and its role in magnetosphere-ionosphere coupling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3445, https://doi.org/10.5194/egusphere-egu23-3445, 2023.

EGU23-3482 | Orals | ST2.4

The controlling effect of the cold plasma density over the acceleration and loss of ultra‐relativistic electrons 

Yuri Shprits, Hayley Allison, Alexander Drozdov, and Dedong Wang

Novel analysis of phase space densities at multiple energies allows for differentiation between various acceleration mechanisms at ultra‐relativistic energies. This method allows us to trace how particles are being accelerated at different energies and show how long it takes for acceleration to reach particular energy. This method clearly demonstrates the importance of local acceleration and also demonstrates the importance of outward radial diffusion in transporting electrons to GEO.

Acceleration to such high energies occurs only when cold plasma in the trough region is extremely depleted, down to the values typical for the plasma sheet. We perform event and statistical analysis of these depletions and show that the ultra‐relativistic energies are reached for each such depletion that is accompanied by the intensification of ~2MeV. VERB‐2D simulations are then used to explain these observations. There is also a clear difference between the loss mechanisms at MeV and multi‐MeV energies due to EMIC waves that can very efficiently scatter ultra‐relativistic electrons but leave MeV electrons unaffected.

Modelling and observations clearly show that cold plasma has a controlling effect over the ultra‐ relativistic electrons that are 10^6‐10^7 times more energetic. We also present how the new understanding gained from the Van Allen Probes mission can be used to produce the most accurate data assimilative forecast. Under the recently funded EU Horizon 2020 Project Prediction of Adverse effects of Geomagnetic storms and Energetic Radiation (PAGER) we study how ensemble forecasting from the Sun can produce long‐term probabilistic forecasts of the radiation environment in the inner magnetosphere.

How to cite: Shprits, Y., Allison, H., Drozdov, A., and Wang, D.: The controlling effect of the cold plasma density over the acceleration and loss of ultra‐relativistic electrons, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3482, https://doi.org/10.5194/egusphere-egu23-3482, 2023.

EGU23-4064 | ECS | Orals | ST2.4

Archimedean Spiral Distribution of Electrons in Earth Inner Magnetosphere 

Weiqin Sun, Jian Yang, Wenrui Wang, and Jun Cui

We present an analytic theory to demonstrate that electrons with an initially asymmetric spatial distribution would form an Archimedean spiral distribution in the inner magnetosphere. Such evolution is a result of the gradient/curvature drift, whose angular velocity decreases with radial distance. It has been known for a long time that spectrograms of energetic electrons in Earth's inner radiation belt exhibit time-varying organized peaks and valleys. Recent observations from Van Allen Probes have shown that such regular patterns are ubiquitous and are referred to as “zebra stripes”. Our theory can predict zebra stripes accurately. We also use the Rice Convection Model (RCM) to simulate zebra stripes. For the simplest situation with the dipolar magnetic field model, the analytic theory perfectly matches with the RCM simulation. In a realistic simulation, the RCM reproduces the time-dependent structures and evolution of the zebra stripes, which are in good consistency with Van Allen Probes observations.

How to cite: Sun, W., Yang, J., Wang, W., and Cui, J.: Archimedean Spiral Distribution of Electrons in Earth Inner Magnetosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4064, https://doi.org/10.5194/egusphere-egu23-4064, 2023.

EGU23-4471 | Orals | ST2.4

Quantifying the Contribution of Nonlinear Resonant Effects to Diffusion Rates 

Dmitri Vainchtein, Anton Artemyev, Didier Mourenas, and Xiaojia Zhang

The wave-particle resonant interaction is a key process controlling energetic electron flux dynamics in the Earth’s radiation belts. All existing radiation belt codes are Fokker-Planck models relying on the quasi-linear diffusion theory to describe the impact of wave-particle interactions. However, in the outer radiation belt, spacecraft often detect waves sufficiently intense to interact resonantly with electrons in the nonlinear regime.

We propose an approach to (1) estimate the contribution of such nonlinear resonant interactions, and (2) include them into diffusion-based radiation belt models. Using statistics of chorus wave-packet amplitudes and sizes (number of wave periods within one packet), we provide a rescaling factor for the quasi-linear diffusion rates to account for the contribution of nonlinear interactions in long-term electron flux dynamics. Such nonlinear effects may speed up 0.1-1 MeV electron diffusive acceleration by a factor of x2-3 during disturbed periods.

How to cite: Vainchtein, D., Artemyev, A., Mourenas, D., and Zhang, X.: Quantifying the Contribution of Nonlinear Resonant Effects to Diffusion Rates, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4471, https://doi.org/10.5194/egusphere-egu23-4471, 2023.

Space plasmas are often characterized by non-thermal particle distributions that are generally characterized by a high-energy tail that follows a power law for large velocity arguments. For modelling purposes, these are often described by kappa-type distributions (Livadiotis, 2017). Over the past few decades, the kappa distribution has been adopted in interpretations of observations in various space plasma contexts including the solar wind (Chotoo et al., 2000), planetary magnetospheres (Collier and Hamilton, 1995), the outer heliosphere (Decker and Krimigis, 2003) and the inner heliosheath (Livadiotis and McComas, 2012) and also in theoretical models (Hellberg et al., 2009). An abundance of data from the Cassini and Voyager missions has established in Saturn's magnetosphere the coexistence of non-thermal electron populations (of different characteristics). Schippers et al. (2008) analysed the radial distribution of electron populations in Saturn's magnetosphere by using an ad hoc two-kappa model, thus establishing the relevance of multi-kappa models with respect to electron populations in Saturn's magnetosphere. This coexistence of electron clouds (at distinct temperatures) is a key element in our work.

Electrostatic Solitary Waves (ESWs), generally associated with bipolar electric field waveforms observed alongside propagating density disturbances, are known to occur in Saturn's magnetosphere (Pickett et al., 2015). In this study, we have relied on a multi-fluid plasma model to investigate the significance of suprathermal electron populations in determining the characteristics of different types of solitary wave solutions. Our investigation reveals that the spectral index (i.e. the  parameter value related to the cold electron population mainly) is crucial in explaining the difference among different types of nonlinear structures. A comparison with spacecraft observations suggests that our theoretical estimations may be relevant in the interpretation of ESW observations in Saturn's magnetosphere.

References

Chotoo, K., Schwadron, N.A., Mason, G.M., Zurbuchen, T.H., Gloeckler, G., Posner, A., Fisk, L.A., Galvin, A.B., Hamilton, D.C., Collier, M.R., 2000. J. Geophys. Res. Space Phys. 105, 23107–23122. https://doi.org/10.1029/1998JA000015

 

Collier, M.R., Hamilton, D.C., 1995. Geophys. Res. Lett. 22, 303–306. https://doi.org/10.1029/94GL02997

 

Decker, R.B., Krimigis, S.M., 2003. Adv. Space Res. 32, 597–602. https://doi.org/10.1016/S0273-1177(03)00356-9

 

Hellberg, M.A., Mace, R.L., Baluku, T.K., Kourakis, I. and Saini, N.S., 2009. Physics of Plasmas, 16(9), p.094701

 

Livadiotis, G., 2017. Kappa Distributions - Theory and Applications in Plasmas (Elsevier).

 

Livadiotis, G., McComas, D.J., 2012. Astrophys. J. 749, 11. https://doi.org/10.1088/0004-637X/749/1/11

 

Pickett, J.S., Kurth, W.S., Gurnett, D.A., Huff, R.L., Faden, J.B., Averkamp, T.F., Píša, D. and Jones, G.H., 2015. Journal of Geophysical Research: Space Physics120(8), pp.6569-6580.

 

Schippers, P., Blanc, M., André, N., Dandouras, I., Lewis, G.R., Gilbert, L.K., Persoon, A.M., Krupp, N., Gurnett, D.A., Coates, A.J., Krimigis, S.M., Young, D.T., Dougherty, M.K., 2008. J. Geophys. Res. Space Phys. 113, https://doi.org/10.1029/2008JA013098

 

 

How to cite: Varghese, S. S. and Kourakis, I.: On the role of suprathermal electrons on the characteristics of electrostatic solitary waves in Saturn’s magnetosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4797, https://doi.org/10.5194/egusphere-egu23-4797, 2023.

EGU23-5059 | ECS | Orals | ST2.4

Nightside plasmaspheric plume-to-core migration of whistler-mode hiss waves 

Zhiyong Wu, Zhenpeng Su, Jerry Goldstein, Nigang Liu, Zhaoguo He, Huinan Zheng, and Yuming Wang

Whistler-mode hiss waves play an important role in the radiation belt electron depletion. Whether the hiss waves with significant differences in amplitude and propagation direction within the plasmaspheric core and plume are related to each other remains unclear. We here show that the plasmaspheric plume facilitates the energy conversion from energetic electrons to hiss waves and then guides hiss waves into the plasmaspheric core. Three ground and space missions captured the initial formation and subsequent rotation of the plasmaspheric plume in the noon-dusk-midnight sector following a strong substorm. The observed hiss waves in the nightside plasmaspheric plume and core propagated oppositely but highly correlated with each other at a time lag of 4-10 s. The linear instability of energetic electrons in the plasmaspheric plume qualitatively explains the frequency-dependence of hiss waves, and the ray-tracing modeling reproduces the propagation direction and timing of hiss waves.

How to cite: Wu, Z., Su, Z., Goldstein, J., Liu, N., He, Z., Zheng, H., and Wang, Y.: Nightside plasmaspheric plume-to-core migration of whistler-mode hiss waves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5059, https://doi.org/10.5194/egusphere-egu23-5059, 2023.

EGU23-7338 | ECS | Posters on site | ST2.4

A number density/temperature description of the Earth’s outer radiation belt 

Dovile Rasinskaite

Substorms can inject electrons of energies ranging from 10s to 100s keV (often called source and seed populations) into the magnetosphere which can be accelerated to relativistic energies and be harmful to space-based infrastructure. Here we present a number density/temperature description of the Earths outer radiation belt obtained by using omni-directional flux and energy measurements from the HOPE and MagEIS instruments from the Van Allen Probe mission. This dataset provides a comprehensive statistical study of the whole Van Allen probe era. Values of number density and temperature are extracted by fitting energy and phase space density in log space to find the distribution function. Zeroth and second moments are taken respectively of the distribution function to find the number density and temperature. A number density/ temperature description is advantageous over an energy/flux description as it allows to differentiate between the transport and heating of electrons. The shape and variation of plasma distributions is also discussed, and general statistical properties presented. The relative importance of transport and heating is also discussed. We will explore the classification of substorm injections (i.e., is the injection a heating or transport of electrons, or a combination of both) and this technique can be extended across more energy ranges. 

How to cite: Rasinskaite, D.: A number density/temperature description of the Earth’s outer radiation belt, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7338, https://doi.org/10.5194/egusphere-egu23-7338, 2023.

EGU23-7524 | Orals | ST2.4

An Empirical Model of Whistler Mode Waves in the Radiation Belt Region 

Ondrej Santolik, Ivana Kolmasova, Ulrich Taubenschuss, Marie Turcicova, and Miroslav Hanzelka

Whistler mode waves interact with different magnetospheric particle populations in the inner magnetosphere and significantly influence particle fluxes in the Earth's radiation belts. Using recently acquired large databases of spacecraft measurements from the Van Allen Probes and Cluster missions we construct new empirical models of whistler mode waves in the inner magnetosphere. We pay special attention to the off-equatorial region, which is often under-sampled in the currently existing models, and to the inter-calibration of data from different spacecraft missions. We take into account the effects of instrumental noise and other artifacts which influence the quality of data at the input of the modeling procedure. Our results show that dawn chorus occurs most often around noon, while its peak average amplitudes are observed during the local night. We also show that off-equatorial plasmaspheric hiss has a strong obliquely propagating component. We further confirm the influence of low plasma density regions on the intensity of chorus.

How to cite: Santolik, O., Kolmasova, I., Taubenschuss, U., Turcicova, M., and Hanzelka, M.: An Empirical Model of Whistler Mode Waves in the Radiation Belt Region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7524, https://doi.org/10.5194/egusphere-egu23-7524, 2023.

EGU23-7785 | Orals | ST2.4

The Angular Distribution of Whistler-Mode Chorus Wave Vector Directions from Van Allen Probes and MMS Observations 

David P. Hartley, Ivar Christopher, Lunjin Chen, Ondrej Santolik, Craig Kletzing, Matthew Argall, and Narges Ahmadi

The dynamics of Earth's outer electron radiation belt is, in part, driven by interactions with whistler-mode chorus waves.  Chorus can cause rapid acceleration of electrons up to relativistic energies, as well as drive precipitation of particles into the atmosphere causing both microbursts and diffuse aurora.  Chorus can propagate in such a way that it crosses the plasmapause boundary and may contribute to the possible sources of plasmaspheric hiss, which itself can cause atmospheric losses of particles and the formation of the slot region between the inner and outer radiation belts.  The direction of the wave vector relative to the background magnetic field is a key parameter for quantifying these processes, since it determines the propagation trajectory of the wave, and is required for calculating the resonance condition of the wave-particle interaction.

The orientation of the wave vector is investigated using both survey mode data and high-resolution burst mode observations from the EMFISIS Waves instrument on the Van Allen Probes spacecraft.  Spatial coverage beyond the Van Allen Probes orbit is provided by burst-mode observations from the FIELDS instrument suite on Magnetospheric Multiscale (MMS).  The polar and azimuthal wave vector angles are considered using both spectral analysis, where the frequency-time structure can be resolved, and instantaneous values, which can be used to identify variations within individual chorus subpackets.  We compare the results from each of these different timescales.  Near strong plasma density gradients, such as those which occur on the boundaries of plasmaspheric plumes, we identify that the wave vector becomes more oblique than the general case where no density gradients are present.  The obliquity of the wave vector is shown to directly relate to both the magnitude of the density gradient, and its proximity to the spacecraft.  

How to cite: Hartley, D. P., Christopher, I., Chen, L., Santolik, O., Kletzing, C., Argall, M., and Ahmadi, N.: The Angular Distribution of Whistler-Mode Chorus Wave Vector Directions from Van Allen Probes and MMS Observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7785, https://doi.org/10.5194/egusphere-egu23-7785, 2023.

EGU23-8042 | ECS | Posters on site | ST2.4

Impact of interplanetary shocks on the radiation belt environment measured by a low altitude satellite 

Stefan Gohl and František Němec

We use electron flux data measured by the Energetic Particle Telescope (EPT) onboard the Proba-V satellite in a Low Earth Orbit (LEO) to investigate the radiation belt response to the interplanetary shock arrival. Altogether, as many as 31 interplanetary shocks selected from the OMNI data during 2013-2018 are investigated. While the radiation belt fluxes are nearly unaffected by the shock arrival in some cases, other events reveal a sudden drop of energetic electron fluxes spanning over a broad range of L-shells. Electron flux changes at various L-shells and energies are evaluated and compared with the solar wind dynamic pressure change across the shock front, magnetopause location, and z-component of the interplanetary magnetic field. The aim is to identify parameters governing the radiation belt response to the interplanetary shock passage and to understand the strikingly different responses to the seemingly similar solar wind variations.

How to cite: Gohl, S. and Němec, F.: Impact of interplanetary shocks on the radiation belt environment measured by a low altitude satellite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8042, https://doi.org/10.5194/egusphere-egu23-8042, 2023.

EGU23-8693 | Orals | ST2.4

Observations and Analysis of Deep Penetrations of MeV Electrons from REPT PHA Data 

Xinlin Li, Declan O'Brien, and Daniel Baker

The Relativistic Electron and Proton Telescope (REPT), consisting of a stack of nine aligned silicon detectors onboard Van Allen Probes, has contributed a great number of discoveries based its nominal data. However, the REPT Pulse Height Analysis (PHA) data set, which was taken every 12 milliseconds (ms), including the pulse height that is proportional to the energy deposit of each individual particle from all nine REPT detectors, has been seldom-tapped. Here we show that this data set actually provides higher energy resolution particle measurements than the typical binned data from REPT. Geant4 simulations are used to extend and improve the electron detecting capabilities of REPT using the PHA data. After replicating the nominal characteristics of REPT in the Geant4 toolbox, new channels for REPT, going from 12 electron channels to 47 and lowering the minimum energy to ~1 MeV, have been formulated. The deep storm-time penetration of MeV electrons into the slot region (2<L<3) and inner belt (L<2) has been investigated. Clear dynamic variations of MeV electrons in these regions are revealed and substantiated by quantitative analysis. This is only an example of how the REPT PHA data will enable us to quantitatively address many more various science questions.

How to cite: Li, X., O'Brien, D., and Baker, D.: Observations and Analysis of Deep Penetrations of MeV Electrons from REPT PHA Data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8693, https://doi.org/10.5194/egusphere-egu23-8693, 2023.

EGU23-8906 | ECS | Orals | ST2.4

Impact of the solar activity on the non-linearity of the statistical dependency between solar wind and the inner magnetosphere 

Sanni Hoilijoki, Veera Lipsanen, Adnane Osmane, Milla Kalliokoski, Harriet George, Lucile Turc, and Emilia Kilpua

Solar wind variations and transients are the main driver of the dynamics of the Earth’s magnetosphere. Interplanetary coronal mass ejections (ICME) cause the largest variations in the near-Earth space, but significant geomagnetic activity can also be driven by high-speed streams (HSSs) and stream interaction regions (SIRs). Solar wind – magnetosphere interactions drive fluctuations in the inner magnetosphere and impact the electrons in the outer radiation belt. Ultra low frequency (ULF) waves in the Pc5 range (2-7mHz) can accelerate electrons in the inner magnetosphere via drift resonance and cause changes in the electron flux up to several orders of magnitude. The different solar wind structures, ICMEs and HSSs/SIRs have been found to have different impact on the ULF waves and electrons in the inner magnetosphere. In this study we use mutual information from information theory to study the statistical dependency of the ULF waves and radiation belt electrons on the solar wind parameters and fluctuations over the solar cycle 23. Unlike Pearson correlation coefficient mutual information can also be used to investigate non-linear statistical dependencies between different parameters. We calculate correlation coefficients separately for each year and find that the non-linearity between the solar wind parameters and some magnetospheric parameters is higher during solar maximum when most of the geomagnetic activity is driven by ICMEs, while the non-linearity decreases during the declining phase, as larger portion of the geomagnetic activity is driven by HSSs and SIRs. To investigate further if the change of the ratio of ICMEs and HSSs is the possible cause of the changes in the non-linearity during the solar cycle, we calculate the correlation coefficients separately during ICMEs, HSSs/SIRs and quiet solar wind.

How to cite: Hoilijoki, S., Lipsanen, V., Osmane, A., Kalliokoski, M., George, H., Turc, L., and Kilpua, E.: Impact of the solar activity on the non-linearity of the statistical dependency between solar wind and the inner magnetosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8906, https://doi.org/10.5194/egusphere-egu23-8906, 2023.

EGU23-8925 | ECS | Orals | ST2.4

Radiation belt particle diffusion, drift and advection via cyclotron interactions 

Oliver Allanson, Jacob Bortnik, Donglai Ma, Adnane Osmane, and Jay Albert

There is a growing body of observational, theoretical and experimental evidence to indicate that a proper description of radiation belt charged particle transport will require new mathematical models, i.e. new partial differential equations. One leading candidate is to extend the ‘standard diffusion equation’ to a more general Fokker-Planck equation in order to include advection coefficients. Ideally, these advection (first-order transport) coefficients should be parameterized by plasma and VLF/ELF electromagnetic wave parameters in a similar manner to that used for the diffusion coefficients. To the authors' knowledge, this goal has not yet been achieved - at least not to obtain an equation that can be/has been implemented into operational global scale numerical models.

In general, advection coefficients are in fact a combination of both ‘drift coefficients’ and derivatives of the diffusion coefficients. In the standard quasilinear formalism, this combination produces advection coefficients that are identically zero because of specific constraints imposed via the Hamiltonian structure, with a derivation often attributed to Landau/Lichtenberg & Lieberman [1].

In this paper [2] we present a new theory that incorporates and builds upon the ‘weak turbulence/quasilinear results’ of [3,4] and demonstrates the breaking of the ‘Landau-Lichtenberg-Liebermann condition’ for the case of high wave amplitudes, or equivalently small timescales.

We therefore obtain:
(i) the standard quasilinear results for small wave amplitudes and long timescales;
(ii) and non-zero advection coefficients - as well as diffusion coefficients - that are valid for short timescales (high wave amplitudes).

These limiting timescales are determined by the electromagnetic wave amplitude. This also demonstrates that one can use what may be considered ‘quasilinear methods’ to obtain interesting new results for ‘nonlinear/high-amplitude’ waves in radiation belt modelling. We verify the results using high-performance test-particle experiments.

References

[1] A.J. Lichtenberg, and M.A. Lieberman, “Regular and Chaotic Dynamics”, 2nd Ed., Springer, 1991

[2] O. Allanson et al (in prep)

[3] D.S. Lemons, PoP, 19, 012306, 2012

[4] O. Allanson, T. Elsden, C. Watt, and T. Neukirch, Frontiers Aston. Space Sci., 8:805699, 2022

How to cite: Allanson, O., Bortnik, J., Ma, D., Osmane, A., and Albert, J.: Radiation belt particle diffusion, drift and advection via cyclotron interactions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8925, https://doi.org/10.5194/egusphere-egu23-8925, 2023.

EGU23-9976 | ECS | Orals | ST2.4

Using pitch angle index to quantify anisotropies in the outer radiation belt 

Ashley Greeley, Shrikanth Kanekal, and Quintin Schiller

Changes in pitch angle distributions can be a useful indicator of various changes in the radiation belts. Many methods of observing pitch angle distributions are qualitative. We present a method of studying pitch angle distributions that allows for a quantitative analysis of pitch angle distributions over time and energy channels, which allows for closer monitoring of spatial and temporal changes in the radiation belts. We use Van Allen Probes data from both spacecraft in fit pitch angle distributions with the form J0sinnα, tracking ‘n’ over time. We use this method of tracking pitch angle distributions to establish a connection between very localized wave particle interactions and particle scattering.

How to cite: Greeley, A., Kanekal, S., and Schiller, Q.: Using pitch angle index to quantify anisotropies in the outer radiation belt, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9976, https://doi.org/10.5194/egusphere-egu23-9976, 2023.

EGU23-10180 | Orals | ST2.4

Characteristic Times for Radiation Belt Drift Phase Mixing 

Solène Lejosne and Jay M. Albert

One of the key assumptions of radiation belt modeling based on a three-dimensional Fokker-Planck equation is that trapped particle fluxes do not depend on the drift phase (i.e., the azimuthal angle, or magnetic local time, MLT). It is usually considered that MLT-dependent structures (such as particle injection signatures and subsequent drift echoes) are rapidly smoothed out by drift phase mixing. Yet, the characteristic times for radiation belt drift phase mixing are not well known.

In this presentation, we show the existence of a naturally occurring phase mixing process in the presence of field fluctuations. This process complements the observational phase mixing due to the finite resolution of the measuring instrument.

We present a first quantification for the characteristic time of natural phase mixing and we discuss the implications in terms of radiation belt modeling.

How to cite: Lejosne, S. and Albert, J. M.: Characteristic Times for Radiation Belt Drift Phase Mixing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10180, https://doi.org/10.5194/egusphere-egu23-10180, 2023.

EGU23-10216 | Orals | ST2.4

Study of Ion Injection into the Inner Magnetosphere Using an Implicit Particle in Cell Simulation Driven by A Global MHD simulation 

Mostafa El Alaoui, Giovanni Lapenta, Liutauras Rusaitis, and Raymond Walker

Observations and magnetohydrodynamic simulations show that not all plasma injections from reconnection in the tail reach the inner magnetosphere to populate the ring current. We have used a self-consistent three-dimension particle-in-cell (PIC) simulation one way coupled to a global magnetohydrodynamic (MHD) simulation of the solar wind-magnetosphere-ionosphere system to investigate the population of the ring current during storm time substorms. This model includes a large fraction of the inner magnetosphere and the near-Earth tail. It allows us to study of the injection of particles from the tail and the interaction of the particles with plasma waves. The calculation begins with electrons and ions propagating earthward from the tail reconnection region. The particle distributions that enter the inner magnetosphere (R < 10 RE) from the magnetotail have a suprathermal component which acts as a seed population for the ring current. We imposed a steady southward IMF with a magnitude of 8 nT at the upstream boundary of the MHD simulation domain for more than three hours. The solar wind number density was 6 cm-3, the thermal pressure was 16 pPa, and the velocity was 530 km/s in the X direction toward Earth.  After we ran the MHD simulation, we chose an interval to examine during which there were several earthward flow channels and dipolarization fronts. Then, we used the output from this time to populate a large PIC simulation domain in the inner magnetosphere. In GSM coordinates, this domain extends over -22 RE <X < 12.5 RE, -13 RE < Y <13 RE, -5 RE < Z < 5 RE. The mass ratio was 256 with realistic ions and more massive electrons. In an initial simulation, we ran the code for 16,000 cycles and found that a ring current developed. We will discuss the reasons why some particles from the tail reach the inner magnetosphere, and some do not by examining how the particles are accelerated and lost.    

How to cite: El Alaoui, M., Lapenta, G., Rusaitis, L., and Walker, R.: Study of Ion Injection into the Inner Magnetosphere Using an Implicit Particle in Cell Simulation Driven by A Global MHD simulation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10216, https://doi.org/10.5194/egusphere-egu23-10216, 2023.

EGU23-10513 | ECS | Posters virtual | ST2.4

EMIC wave induced proton precipitation during the 27-28 May 2017 storm:Comparison of BATSRUS+RAM-SCB simulations with ground/space based observations 

Shreedevi Porunakatu Radhakrishna, Yiqun Yu, Yoshizumi Miyoshi, Xingbin Tian, Minghui Zhu, Sandeep Kumar, Satoko Nakamura, Chae-Woo Jun, Masafumi Shoji, Kazuo Shiokawa, Vania Jordanova, Tomoaki Hori, Kazushi Asamura, Iku Shinohara, Shoichiro Yokota, Satoshi Kasahara, Kunihiro Keika, Ayako Matsuoka, Martin Connors, and Akira Kadokura

Recent studies have shown that the ion precipitation induced by EMIC waves can contribute significantly to the total energy flux deposited into the ionosphere and severely affect the magnetosphere-ionosphere coupling. During the geomagnetic storm of 27-28 May 2017, the ARASE and the RBSPa satellites observed typical signatures of EMIC waves in the inner magnetosphere. The DMSP and MetOp satellites observed enhanced proton precipitation during the main phase of the storm. In order to understand the evolution of proton precipitation into the ionosphere, its correspondence to the time and location of excitation of the EMIC waves and its relation to the source and distribution of proton temperature anisotropy, we conducted two simulations of the BATSRUS+RAMSCBE model with and without EMIC waves included. Simulation results suggest that the H- and He-band EMIC waves are excited within regions of strong temperature anisotropy of protons in the vicinity of the plasmapause. In regions where the Arase/RBSPa satellite measurements recorded EMIC wave activity, an increase in the simulated growth rates of H- and He-band EMIC waves is observed indicating that the model is able to capture the EMIC wave activity. The RAM-SCBE simulation with EMIC waves reproduces the precipitating fluxes in the premidnight sector fairly well, and is found to be in good agreement with the DMSP and MetOp satellite observations. The results suggest that the EMIC wave scattering of ring current ions gives rise to the proton precipitation in the premidnight sector at subauroral latitudes during the main phase of the 27 May 2017 storm.

How to cite: Porunakatu Radhakrishna, S., Yu, Y., Miyoshi, Y., Tian, X., Zhu, M., Kumar, S., Nakamura, S., Jun, C.-W., Shoji, M., Shiokawa, K., Jordanova, V., Hori, T., Asamura, K., Shinohara, I., Yokota, S., Kasahara, S., Keika, K., Matsuoka, A., Connors, M., and Kadokura, A.: EMIC wave induced proton precipitation during the 27-28 May 2017 storm:Comparison of BATSRUS+RAM-SCB simulations with ground/space based observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10513, https://doi.org/10.5194/egusphere-egu23-10513, 2023.

EGU23-10543 | ECS | Posters on site | ST2.4

Outer radiation belt electron flux and phase space density changes during sheath regions of coronal mass ejections from Van Allen Probes and GPS data 

Milla Kalliokoski, Michael Henderson, Steven Morley, Emilia Kilpua, Adnane Osmane, Leonid Olifer, Drew Turner, Allison Jaynes, Harriet George, Sanni Hoilijoki, Lucile Turc, and Minna Palmroth

Turbulent and compressed sheath regions ahead of interplanetary coronal mass ejections are key drivers of dramatic changes in the electron fluxes in the Earth’s outer radiation belt. They are also associated with elevated wave activity in the inner magnetosphere. These changes in electron fluxes can occur on timescales of tens of minutes that are not readily captured by a two-satellite mission such as the Van Allen Probes due to long revisit times. The recently released Global Positioning System (GPS) data set, on the other hand, provides a larger number of measurements at a given location within a given amount of time, owing to the many satellites in the constellation. In our statistical study on the impact of sheath regions on the outer radiation belt, we investigated events in 2012-2018 at timescales of 6 hours (Van Allen Probes data) and 30 minutes (GPS data). The study showed that the flux response to sheaths as reported from Van Allen Probes observations is reproduced by GPS data.  We highlight that the shorter timescale allowed by GPS data further confirms that the energy and L-shell dependent flux changes are associated with the sheaths rather than the following ejecta. Additionally, we studied the electron phase space density, which is a key quantity for identifying non-adiabatic electron dynamics. This showed that electrons are effectively accelerated only during geoeffective sheaths (SYM-H < -30 nT). Outer belt losses are common for all sheaths, and the lost electrons are replenished during the early ejecta.

How to cite: Kalliokoski, M., Henderson, M., Morley, S., Kilpua, E., Osmane, A., Olifer, L., Turner, D., Jaynes, A., George, H., Hoilijoki, S., Turc, L., and Palmroth, M.: Outer radiation belt electron flux and phase space density changes during sheath regions of coronal mass ejections from Van Allen Probes and GPS data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10543, https://doi.org/10.5194/egusphere-egu23-10543, 2023.

EGU23-10778 | ECS | Posters virtual | ST2.4

Plasma pressure distribution of ions and electrons in the inner magnetosphere during CIR driven storms observed during Arase satellite era 

Sandeep Kumar, Yoshizumi Miyoshi, Vania Koleva Jordanova, Lynn M Kistler, Inchun Park, Porunakatu Radhakrishna Shreedevi, Kazushi Asamura, Shoichiro Yokota, Satoshi Kasahara, Yoichi Kazama, Shiang -Yu Wang, Sunny W. Y. Tam, Takefumi Mitani, Nana Higashio, Kunihiro Keika, Tomo Hori, Chae-Woo Jun, Ayako Matsuoka, Shun Imajo, and Iku Shinohara

Geomagnetic storms are the main component of space weather. Enhancement of the ring current is a typical feature of the geomagnetic storm and a global decrease in the H component of the geomagnetic field is observed during the main phase of the geomagnetic storm.  The ring current represents a diamagnetic current driven by the plasma pressure in the inner magnetosphere. The plasma pressure is mainly dominated by protons in an energy range of a few to a few hundred keVs during quiet times. The O+ contribution is also important, and sometimes dominates more than H+ during intense geomagnetic storms. However, electron contribution to the ring current is not studied well. Recently, we showed that the electron pressure also contributes to the depression of ground magnetic field during the November 2017 CIR-driven storm by comparing Ring current Atmosphere interactions Model with Self Consistent magnetic field (RAM-SCB) simulation, Arase in-situ plasma/particle data, and ground-based magnetometer data [Kumar et al., 2021]. Arase satellite observed 26 geomagnetic storms driven by Corotating Interaction Regions (CIR) during 2017-2021. In this study, we examine statistically the spatial and temporal distribution of ions (H+, He+, O+) and electrons pressure as a function of magnetic local time, L shell and wide range of energies during prestorm, main phase, early recovery and late recovery phase for 26 CIR storms using in situ plasma/particle data obtained by Arase. The results indicate that the electrons (20-50 keV) contribution to the ring current pressure is non-negligible.

How to cite: Kumar, S., Miyoshi, Y., Jordanova, V. K., Kistler, L. M., Park, I., Shreedevi, P. R., Asamura, K., Yokota, S., Kasahara, S., Kazama, Y., Wang, S.-Y., Tam, S. W. Y., Mitani, T., Higashio, N., Keika, K., Hori, T., Jun, C.-W., Matsuoka, A., Imajo, S., and Shinohara, I.: Plasma pressure distribution of ions and electrons in the inner magnetosphere during CIR driven storms observed during Arase satellite era, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10778, https://doi.org/10.5194/egusphere-egu23-10778, 2023.

The polar wind, consisting of low-energy ions and electrons, is an outflow along the open magnetic field lines from the polar cap ionosphere to the magnetosphere. Previous studies found that both solar radiation and solar wind electromagnetic energy are the two main energy sources for the polar wind. The polar rain, being field-aligned precipitating electrons from the solar wind to the polar cap, may provide additional energies for the polar wind. This scenario is complicated as simulation studies show that polar rain changes the electric potential structures over the polar cap ionosphere. It is unclear how the polar rain affects the polar wind ion outflow. In this study, we show a positive correlation between the polar wind and the polar rain. Meanwhile, the polar wind is generally diminished in regions with strong Earth’s magnetic field, suggesting the B modulates the penetration depth of the polar rain through the magnetic mirror force and thus the energy dissipation of the polar rain. Therefore, the polar rain can be an additional energy source for the polar wind although the polar rain has generally smaller energies and intensities than the particle precipitations in the auroral regions.

How to cite: Li, K.: The effects of the polar rain on the polar wind ion outflow from the nightside ionosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11056, https://doi.org/10.5194/egusphere-egu23-11056, 2023.

EGU23-11084 | ECS | Posters on site | ST2.4

A Missing Dusk-side Loss Process in the Electron Ring Current 

Bernhard Haas, Yuri Y. Shprits, Michael Wutzig, Dedong Wang, and Mátyás Szabó-Roberts

The Earth’s magnetic field traps charged particles which are transported longitudinally around Earth, generating a near-circular current, known as the ring current. While the ring current has been measured on the ground and space for many decades, the enhancement of the ring current during geomagnetic storms is still not well understood, due to many processes contributing to its dynamics on different time scales. The low energy part of the ring current of 10-50 keV is responsible for surface charging effects on spacecraft, potentially causing satellite anomalies.

Here, we show that existing ring current models systematically overestimate the in-situ satellite measurements of the Earth’s night side electron ring current during geomagnetic storms. By analyzing electron drift trajectories during the storm onset, we show that this systematic overestimation of flux can be explained through a missing loss process which operates in the pre-midnight sector. Quantifying this loss reveals that the theoretical upper limit of strong diffusion has to be reached in a broad region of space in order to reproduce the observed flux. We include this missing loss process and show that predictions of electron flux can be significantly improved. Identifying missing loss processes in ring current models is vital to accurately predict storm time dynamics and the associated hazards, that result from a delicate balance of source and loss processes.

How to cite: Haas, B., Shprits, Y. Y., Wutzig, M., Wang, D., and Szabó-Roberts, M.: A Missing Dusk-side Loss Process in the Electron Ring Current, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11084, https://doi.org/10.5194/egusphere-egu23-11084, 2023.

EGU23-12704 | ECS | Posters on site | ST2.4

Studying the South Atlantic Anomaly temporal evolutionfrom 1998 to 2022 using the SEM-2 proton flux 

François Ginisty, Frédéric Wrobel, Robert Ecoffet, Mioara Mandea, Alain Michez, Nicolas Balcon, Marine Ruffenach, and Julien Mekki

The SEM-2 (Space Environment Monitor-2) instrument embedded on the NOAA-15 Low Earth Orbit satellite provides measurements of trapped protons in the Van Allen inner belt from 1998 to nowadays. This continuous amount of measurements enables us to study the temporal evolution of the dynamics of the South Atlantic Anomaly (SAA) over more than two solar cycles.
In particular, we study the temporal evolution of the area of the SAA. We observe that the area of the SAA is anti-correlated with the solar activity. Two physical process explain this anticorrelation.
First, the more the Sun is active the more it disables the cosmic rays to reach the Earth Magnetosphere and to fill the inner radiation belt with protons. Then, when the Sun in more active, the upper atmosphere is warmer and therefore absorbs more protons from the radiation belt.
Then, we investigate the protons flux centroid of the SAA. The temporal evolution of its position, latitude and, longitude is studied over the same time interval (1998-2022). We notice the latitude of the centroid is also anti-correlated with the solar activity whereas the longitude seems absolutely
independent. Some explanations are given for these observations.
The temporal evolution of the position of the centroid shows a drift of the SAA. Indeed from 1998 to 2022 the SAA drifted of about 7 degrees West.
The SEM-2 instrument measures flux for protons of different energies (16, 36, 70 and, 140 MeV). For each energy, the SAA dynamic has a similar trend but with different values. These differences are investigated and the results discussed.

How to cite: Ginisty, F., Wrobel, F., Ecoffet, R., Mandea, M., Michez, A., Balcon, N., Ruffenach, M., and Mekki, J.: Studying the South Atlantic Anomaly temporal evolutionfrom 1998 to 2022 using the SEM-2 proton flux, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12704, https://doi.org/10.5194/egusphere-egu23-12704, 2023.

EGU23-13125 | ECS | Posters on site | ST2.4

Investigating Solar Wind Drivers of Ultrarelativistic Electron Enhancements in the Outer Radiation Belt 

Matyas Szabo-Roberts, Yuri Shprits, and Hayley Allison

A distinct population of ultrarelativistic electrons has been observed in the outer radiation belt after several geomagnetic storms, and recent modeling results indicate that an existing seed population, and depletions in plasmasphere electron density, are a necessary condition for the appearance of this electron population. In order to similarly deepen our understanding of the solar wind drivers behind the appearance of these electrons with extreme energy, we catalog storms corresponding to ultrarelativistic enhancements by origin, and begin to establish necessary and sufficient solar wind conditions for these enhancement events. To do so, we perform superposed epoch analysis on a 6 year period from 2012 to 2018, using solar wind data from the Omniweb service, as well as electron flux and electron density data products from the Van Allen Probes mission. We also provide an overview of further modeling objectives and open questions for continued investigation of this electron population.

How to cite: Szabo-Roberts, M., Shprits, Y., and Allison, H.: Investigating Solar Wind Drivers of Ultrarelativistic Electron Enhancements in the Outer Radiation Belt, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13125, https://doi.org/10.5194/egusphere-egu23-13125, 2023.

EGU23-13189 | ECS | Posters virtual | ST2.4

Impact of Interplanetary Coronal Mass Ejections and High Speed Streams on the dynamic variations of the electron population in the outer Van Allen belt 

Adamantia Dimitrakoula, Alexandra Triantopoulou, Afroditi Nasi, Christos Katsavrias, Ioannis A. Daglis, and Ingmar Sandberg

The outer Van Allen radiation belt stands out for its intense variability, due to the complex mechanisms that take place due to the Sun – Earth coupling. One fundamentally important effect is the acceleration of seed electrons to relativistic and ultra – relativistic energies, through different mechanisms, namely radial diffusion and local acceleration.

In our work, we examine 46 events from the Van Allen Probes era (2012 – 2018), which we categorize according to the interplanetary driver of the geomagnetic disturbance. In particular, we study 16 events caused by Interplanetary Coronal Mass Ejections (ICMEs) and 30 events caused by High Speed Streams (HSS), following Stream Interaction Regions (SIRs), for which we calculate the electron Phase Space Density (PSD) for distinct values of the first adiabatic invariant (μ = 100, 1000, 5000 MeV/G) corresponding to seed, relativistic and ultra – relativistic electrons in the outer radiation belt. Furthermore, we perform a Superposed Epoch Analysis (SEA) of the geomagnetic disturbance events, which lead to either enhancements or depletions of the electron PSD, taking into consideration the parameters of solar wind activity, the state of the magnetosphere and the values of the second adiabatic invariant (K = 0.03, 0.09, 0.15 G1/2RE). We discuss the effects of the drivers on the variability of the outer radiation belt and how the different electron populations are affected, by comparing the time and radial profiles of the PSD. Our results lead to a clear difference between the two drivers, as far as it concerns the acceleration mechanisms.

How to cite: Dimitrakoula, A., Triantopoulou, A., Nasi, A., Katsavrias, C., Daglis, I. A., and Sandberg, I.: Impact of Interplanetary Coronal Mass Ejections and High Speed Streams on the dynamic variations of the electron population in the outer Van Allen belt, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13189, https://doi.org/10.5194/egusphere-egu23-13189, 2023.

EGU23-14289 | Posters on site | ST2.4

Developing Chorus Wave Model Using Van Allen Probe and Arase Data 

Dedong Wang, Yuri Shprits, Ting Feng, Thea Lepage, Ingo Michaelis, Yoshizumi Miyoshi, Yoshiya Kasahara, Atsushi Kumamoto, Shoya Matsud, Ayako Matsuoka, Satoko Nakamura, Iku Shinohara, and Fuminori Tsuchiiya

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 intercalibration, 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: Wang, D., Shprits, Y., Feng, T., Lepage, T., Michaelis, I., Miyoshi, Y., Kasahara, Y., Kumamoto, A., Matsud, S., Matsuoka, A., Nakamura, S., Shinohara, I., and Tsuchiiya, F.: Developing Chorus Wave Model Using Van Allen Probe and Arase Data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14289, https://doi.org/10.5194/egusphere-egu23-14289, 2023.

EGU23-15611 | Orals | ST2.4

Observations of Off-Equatorial ULF Waves and Simulations of their effects on Radial Diffusion in the Radiation Belts 

Theodore Sarris, Xinlin Li, Hong Zhao, Kostis Papadakis, Wenlong Liu, Weichao Tu, Vassilis Angelopoulos, Karl-Heinz Glassmeier, Yoshizumi Miyoshi, Ayako Matsuoka, Iku Shinohara, and Shun Imajo

Magnetospheric ultra-low frequency (ULF) waves are known to cause radial diffusion and transport of hundreds-keV to few-MeV electrons in the radiation belts, as the range of drift frequencies of such electrons overlaps with the frequencies of the waves, leading to resonant interactions. Numerous expressions have been derived to quantitatively describe radial diffusion, so that they can be incorporated in global models of radiation belt electrons; however, most expressions of the radial diffusion rates are derived only for equatorially mirroring electrons, and are based on estimates of the power of ULF waves that are obtained either from spacecraft close to the equatorial plane or from the ground. Recent studies using the Van Allen Probes and Arase have shown that the wave power in magnetic fluctuations is significantly enhanced away from the magnetic equator, consistent with models simulating the natural modes of oscillation of magnetospheric field lines. This has significant implications for the estimation of radial diffusion rates, as higher pitch angle electrons will experience considerably higher ULF wave fluctuations than equatorial electrons. In this talk, we present recent results on the distribution of the magnetic field wave power as a function of magnetic latitude in different local time sectors and under different solar and geomagnetic conditions. Furthermore, using analytic functions of wave amplitudes in 3D test particle simulations, we simulate the change in L over time for particles of different pitch angles; this change in L can be translated to novel analytic diffusion coefficients with pitch-angle, L and energy dependence. In this talk we discuss the potential implications for the radial diffusion rates as currently estimated.

How to cite: Sarris, T., Li, X., Zhao, H., Papadakis, K., Liu, W., Tu, W., Angelopoulos, V., Glassmeier, K.-H., Miyoshi, Y., Matsuoka, A., Shinohara, I., and Imajo, S.: Observations of Off-Equatorial ULF Waves and Simulations of their effects on Radial Diffusion in the Radiation Belts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15611, https://doi.org/10.5194/egusphere-egu23-15611, 2023.

EGU23-15928 | Posters on site | ST2.4

Proton precipitation from EMIC waves at high latitudes: A casestudy from 29 March 2021 

Patrizia Francia, Marcello DE Lauretis, Mirko Piersanti, Giulia D'Angelo, and Alexandra Parmentier

Electron precipitation driven by electromagnetic ion cyclotron (EMIC) waves in the Pc1 range (0.1–5Hz) has been suggested as a significant loss mechanism for outer radiation belt fluxes of electrons in the 1–5 MeV energy range. Moreover, EMIC waves have been also observed to cause significant precipitation of ring current protons during geomagnetic storms.
In this study we report the concurrent observations of electromagnetic ion cyclotron Pc1 waves in both ionospheric F-region and at ground. Key event on March 29, 2021 shows that high latitude ground magnetometers in Antarctica and CSES LEO satellite detected concurrent Pc1 wave and energetic proton precipitation. In the ionospheric F-layer above the Auroral zone, the CSES satellites observed transverse Pc1 waves and localized plasma density enhancement, which is occasionally surrounded by wide/shallow depletion. This might indicate that EMIC wave-induced proton precipitation contributes to the energy transfer from the magnetosphere to the ionosphere and to the ionization of the F-layer.

How to cite: Francia, P., DE Lauretis, M., Piersanti, M., D'Angelo, G., and Parmentier, A.: Proton precipitation from EMIC waves at high latitudes: A casestudy from 29 March 2021, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15928, https://doi.org/10.5194/egusphere-egu23-15928, 2023.

EGU23-15979 | ECS | Posters on site | ST2.4

Auroral oval identification based on Swarm magnetometer data 

Margot Decotte, Spencer Hatch, Karl Laundal, and Jone Reistad

Following the work done with the DMSP spectrometer data to derive the auroral occurrence probability in all covered MLat-MLT sectors above 50 degrees MLat (Decotte et al. 2023), here we use the Swarm magnetometer data to extract the probability to detect magnetic field perturbations in the East--West direction. We derive the integrated spectral density from the magnetic field data in a given frequency band, and we define a minimum power threshold above which fluctuations would indicate field-aligned currents. We obtain MLat-MLT distributions of magnetic field fluctuations for various geomagnetic conditions. We find strong similarities between the preferred region of magnetic perturbations and the Xiong and Lühr auroral boundaries (2014), suggesting that the auroral oval morphology could be investigated through magnetic field spectral power estimates. We compare the magnetic field fluctuation probability with the auroral occurrence probability (DMSP particle data) and we find a recurrent dawn-dusk asymmetric pattern in both distributions.  

How to cite: Decotte, M., Hatch, S., Laundal, K., and Reistad, J.: Auroral oval identification based on Swarm magnetometer data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15979, https://doi.org/10.5194/egusphere-egu23-15979, 2023.

EGU23-16056 | ECS | Posters on site | ST2.4

VLF banded structured events observed in the 5–39 kHz frequency range in Finland 

Liliana Macotela, Jyrki Manninen, and Martin Fullekrug

Analysis of very low frequency (VLF) radio waves provides us the remarkable possibility of investigating the response of both the lower ionosphere and magnetosphere to a diversity of transient and long-term physical phenomena originating on Earth (e.g., atmospheric waves) or in space (e.g., CMEs). In this work, broadband VLF data measured at Kannuslehto, in northern Finland, is used to characterize a new type of VLF emissions displaying a strip-like structure observed in the 5–39 kHz frequency range. Analyzing campaigns from 2006 to 2022, we found that this emission can be observed either in the high VLF frequency ranges or spanning from low to high frequency ranges. We also found that the events last usually less than 1 hour, occur during evening hours, and during quiet geomagnetic conditions. We discuss the seasonal dependence of this kind of events by analyzing a complete year during 2022. We also discuss whether their origin might be due to plasma instabilities in the magnetosphere, as in the case of auroral hiss.

How to cite: Macotela, L., Manninen, J., and Fullekrug, M.: VLF banded structured events observed in the 5–39 kHz frequency range in Finland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16056, https://doi.org/10.5194/egusphere-egu23-16056, 2023.

EGU23-16202 | ECS | Posters virtual | ST2.4

Observation of VLF transmitter induced electron precipitation of up to 400keV 

Coralie Neubüser, Roberto Battiston, Francesco Maria Follega, William Jerome Burger, Mirko Piersanti, and Dario Recchiuti

Ground-based very low frequency (VLF; 10-30kHz) transmitters have been found in previous studies to emit whistler waves that can re- sonate with high-energy particles (>100keV) in the radiation belt, causing energetic electron precipitation via pitch angle scattering. In the attempt to find a similar mechanism responsible for electron precipitation due to EM waves emitted during seismic events, we ha- ve analysed three years of data (2019-2021) from the China Seismo- Electromagnetic Satellite (CSES) and the NOAA POES satellites. We found enhanced electron fluxes due to the 19.8kHz waves of the NWC transmitter in Australia at L-shell values of about 1.5 and 1.8 at energies up to 400keV in the data of the CSES and NOAA POES-19 sa- tellite, respectively. The enhanced fluxes can be followed along the drift shells from Australia eastwards, and are observed to be lost in the the South Atlantic Anomaly (SAA) due to the interaction with the atmosphere. The high energy resolution of the HEPP-L detector on board CSES of 11keV from 0.1 to 3MeV allows a detailed study of the signal and we will present the expected energy-dispersed wisp struc- ture in L-shell. Finally, we will present our latest results on the identification of isolated electron bursts and the assignment to dif- ferent VLF transmitters, which includes the correlation of VLF wave measurements from ground and space-based instruments to determined on/off periods of the transmitters.

How to cite: Neubüser, C., Battiston, R., Follega, F. M., Burger, W. J., Piersanti, M., and Recchiuti, D.: Observation of VLF transmitter induced electron precipitation of up to 400keV, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16202, https://doi.org/10.5194/egusphere-egu23-16202, 2023.

EGU23-17001 | Orals | ST2.4

A new mechanism for early time plasmaspheric refilling 

Raluca Ilie, Jianghuai Liu, Michael Liemohn, and Joseph Borovky

We present a robust assessment of the formation and evolution of the cold H+ population produced via charge-exchange processes between ring current ions and exospheric neutral hydrogen in the inner magnetosphere, inferred via numerical simulations of the near-Earth plasma using a drift kinetic model of the ring current-plasmasphere system.

We evaluate the flow of mass and energy through the inner magnetospheric system and show that the production and evolution of the cold H+ population can be primarily driven by the plasma sheet conditions and dynamics and has the potential to reshape the plasmasphere and enhance the early-stage plasmaspheric refilling. We present evidence that the plasma sheet heavy ion composition is the primary controlling factor in the formation of the cold H+ via charge exchange with the geocorona, while the neutral density plays a much smaller role.

How to cite: Ilie, R., Liu, J., Liemohn, M., and Borovky, J.: A new mechanism for early time plasmaspheric refilling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17001, https://doi.org/10.5194/egusphere-egu23-17001, 2023.

EGU23-17213 | Orals | ST2.4

New pathways for EMIC wave propagation within the ionosphere: SWARM observations and modelling 

Robert Rankin, Dmytro Sydorenko, and Ian R Mann

Electromagnetic ion cyclotron (EMIC) waves are important because of their essential role in reducing the amount of radiation in the Earth's radiation belts under geomagnetic storm conditions. In this presentation, we show results from a new simulation model of EMIC waves and compare them with SWARM satellite data and ground-based observations [I. P. Pakhotin et al., Geophys. Res. Lett., 2022, doi:10.1029/2022GL098249]. The EMIC wave model is a first-of-a-kind in accounting for wave propagation in the magnetosphere and a realistic ionosphere specified using the IRI and MSIS empirical models. The inclusion of a realistic ionosphere in the model enables new pathways to the upper atmosphere to be identified, which is crucial for understanding the waves detected on the ground. We show using a model-data comparison that EMIC wave energy is reflected at different locations in the ionosphere toward the equator to form standing waves. This is a new resonance phenomenoncreated by interference of waves that produces an amplitude peak in the upper atmosphere at lower latitudes, far from the location of the initial source. Understanding such pathways is crucial for correctly diagnosing the location of EMIC wave populations in space, and assessing their role in radiation belt loss.

How to cite: Rankin, R., Sydorenko, D., and Mann, I. R.: New pathways for EMIC wave propagation within the ionosphere: SWARM observations and modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17213, https://doi.org/10.5194/egusphere-egu23-17213, 2023.

EGU23-17286 | ECS | Orals | ST2.4

Nonlinear Scattering of Relativistic Electrons by Oblique EMIC Waves 

Miroslav Hanzelka, Wen Li, Qianli Ma, and Luisa Capannolo

Electrons in the Earth’s outer radiation belt can experience rapid energization and pitch angle scattering through interactions with naturally generated electromagnetic waves. Cyclotron resonant interactions with large amplitude electromagnetic ion cyclotron (EMIC) emissions cause scattering and major atmospheric losses of relativistic electrons in the sub-MeV and MeV energy range. While theory and simulations in the past focused mostly on parallel propagating waves, in-situ spacecraft observations of EMIC waves commonly show quasi-parallel or moderately oblique propagation.

Here we present the results of test-particle analysis of electron interaction with helium band and hydrogen band EMIC waves parametrized by wave normal angle (WNA) and wave amplitude. It is shown that nonlinear phase trapping and the associated transport of electrons to low-pitch angles become efficient only at very large amplitudes (> 1% of the background magnetic field), especially in the helium band frequency range, making the nonlinear effects less important than in the whistler-electron interaction case. Harmonic resonant interactions with oblique waves further increase the probability of detrapping, pushing the pitch angle evolution closer to pure diffusion. We also analyze the pitch angle behavior near the loss cone and study the evolution of phase space density (PSD) through the Liouville mapping method. Despite the significant advection effects caused by force-bunching of resonant electrons at low pitch angles, the PSD in the loss cone exhibits behavior similar to strong diffusion. We argue that this is expected to be the case for any bursty precipitation caused by cyclotron resonant interactions.

The wave normal angle has only minor impact on the precipitation rate in the energy range affected by the off-equatorial fundamental resonance, except for the case of very oblique waves (WNA > 70 deg). However, since oblique EMIC waves are elliptically polarized and interact with both co-streaming and counter-streaming electrons, they can enhance the changes in the pitch angle of mirrored (trapped) relativistic electrons. The scattering efficiency for counter-streaming electrons strongly depends on the wave ellipticity, and in turn, on wave frequency, wave normal angle, and ion composition. Our simulation results support the need for accurate wave normal angle and amplitude distribution to quantify the relativistic electron precipitation to the Earth’s atmosphere.

How to cite: Hanzelka, M., Li, W., Ma, Q., and Capannolo, L.: Nonlinear Scattering of Relativistic Electrons by Oblique EMIC Waves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17286, https://doi.org/10.5194/egusphere-egu23-17286, 2023.

ST3 – Ionosphere and Thermosphere

On 21 June 2020, an annular solar eclipse pass over Africa, Europe, and Asia.  When the moon’s shadow sweeps, the solar radiation is blocked out and leads to weak photochemical effects and other variations on the ionosphere.  The ion/electron temperature, density, and the ion vertical drift velocity measured by multi-satellites have been estimated and analyzed.  EFI (Electric Field Instrument) onboard Swarm with a circular orbit of 88° inclination and 530 km altitude provides the data of electron temperature and density.  IVM (ion velocity meter) onboard FORMOSAT-7/COSMIC-2 (F7/C2) with a circular orbit of 24° inclination and 550 km altitude supplies information on the ion temperature, density, and ion vertical drift velocity.  IVM onboard Ionospheric Connection Explorer (ICON) with a circular orbit of 27° inclination and 579 km altitude offers the same parameters as F7/C2.  On the event day, a total of 9 paths of those satellites passed through the greatest eclipse path, 6 from F7/C2, 2 from ICON, and 1 from Swarm.  Referencing one-month data of each satellite path, both ion and electron temperature decrease about 500K after the maximum contact.  Three of the four solar eclipse signatures in the ion density are observed, including pre-ascensions, major depressions, and sunset ascensions.  Moreover, the ion drift velocity tends to be downward around the maximum contact.  Detailed results will be presented and discussed.

How to cite: Kao, T.-H. and Liu, J.-Y.: Swarm, FORMOSAT-7/COSMIC-2, and ICON ionospheric observations during the annular solar eclipse on 21 June 2020, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-596, https://doi.org/10.5194/egusphere-egu23-596, 2023.

EGU23-597 | ECS | Posters on site | ST3.1

Hemispheric Asymmetries in the Ionospheric Total Electron Content during 1999-2019 

Yu-Chi Chang and Jann-Yenq Liu

This paper studies the hemispheric asymmetry of the total electron content (TEC) by means of the Global Ionosphere Map (GIM), which has been routinely publishing every 2 hours by the Center for Orbit Determination in Europe (CODE) during 1999-2019.  The study period including the solar cycles 23 and 24 allows us globally uniformly examine the ionospheric asymmetry phenomenon of the GIM TEC in the different solar activities.  At each time point, summations of the GIM TEC at low-, mid-, and high-latitude in the northern and southern hemispheres are computed.  Results reveal the maximum summations of the GIM TEC occurring in April or November and the minimum summations of the GIM TEC occurring in July, which indicates the extreme TEC values in each year are not at the equinox or solstice.  We compare the sums of the two hemispheres in various local times, months, and solar activities.  By computing the annual magnitude of the asymmetry phenomenon, it is found that the asymmetric phenomenon is more prominent during the low solar activity, although its fluctuation is proportional to the F10.7 index.  We further study the asymmetry phenomenon in various latitudes and find the latitudes with prominent signatures.

How to cite: Chang, Y.-C. and Liu, J.-Y.: Hemispheric Asymmetries in the Ionospheric Total Electron Content during 1999-2019, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-597, https://doi.org/10.5194/egusphere-egu23-597, 2023.

EGU23-685 | ECS | Posters on site | ST3.1

Ground and Ionospheric Signatures of Solar Wind-Magnetosphere Interaction at Mid-Latitudes 

Ezgi Gülay, Zerefşan Kaymaz, and Emine Ceren Kalafatoğlu Eyigüler

As we enter the increasing solar activity epoch, the space weather phenomena and predictions become crucially important to avoid the effects on our lives and technology which is becoming more space-dependent every day. One of the key issues in space weather is to determine the worldwide signatures of the solar wind-magnetosphere-ionosphere coupling. While the response of the high and low latitude regions on Earth to the space weather phenomena is well established, the signatures at the mid-latitudes comparatively are less explored. Being farther from both the auroral and the equatorial latitudes, mid-latitude signatures of the solar wind-magnetosphere interaction can be more complex and may not be so straightforward. In this study, the effects of the geomagnetic activity are investigated using observational tools which are unique to its geographical region, north-west Turkey. Dynasonde radar measurements (Dynasonde at ITU Campus, 41°N, 29°E), magnetotelluric measurements of ground electric field (Magnetotelluric station at Bozcaada, 39.5°N, 26°E), and geomagnetic field variations (Geomagnetic observatory at Iznik, 40.43°N, 29.72°E) are combined to obtain a global perspective of the space weather effects in this mid-latitude region. Magnetically active periods were determined using Dst index and the variations in the corresponding ionospheric electron density and the geomagnetically induced currents (GICs) were analyzed based on the case studies as well as statistical tools.  More than 20 indicators such as differences in the fields, extreme values, averages, and storm durations were analyzed and their relations to magnetic storms as well as solar wind and interplanetary magnetic field (IMF) connections were studied.  GICs were investigated based on the variations in the horizontal magnetic field. The dependence on the magnetic storm phases was revealed. One of the most intriguing results from both case studies and statistical analysis is that stronger GICs were found in our region during the recovery phase of the geomagnetic storms. The electron density variations indicated both positive and negative effects during the storms.  The magnitudes of the variations for both GICs and electron density variations were determined.  While the case studies indicate close relations with geomagnetic indices, solar wind, and IMF variations, statistical results resulted in small correlation coefficients.  This emphasizes and further indicates the importance of the statistical indicator that is used in the correlation analysis. In this presentation, solar wind-magnetosphere connection to the ionosphere and to the ground will be discussed in view of our findings.  It is believed that these results will improve our understanding of the cause-and-effect of the space weather phenomena at mid-latitudes while at the same time, it will give support to global space weather modeling studies.

How to cite: Gülay, E., Kaymaz, Z., and Kalafatoğlu Eyigüler, E. C.: Ground and Ionospheric Signatures of Solar Wind-Magnetosphere Interaction at Mid-Latitudes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-685, https://doi.org/10.5194/egusphere-egu23-685, 2023.

To study ionospheric climate and to study its long-term changes and trends we need solar activity proxies, because long and homogeneous data series of solar ionizing flux are not available. Also models like IRI are based on solar proxies. To select the optimum solar activity proxies, we use yearly average foF2 data of six ionospheric stations from middle latitudes of four continents over 1976-2014 and six solar activity proxies, F10.7, sunspot numbers, F30, Mg II, He II and solar Lyman-α flux. The highest percentage of total variance of yearly foF2 is described equally by F30 and Mg II. However, when we divide period 1976-2014 into two parts, 1976-1995 and 1996-2014, F30 is the only proxy which reveals the same dependence of foF2 on solar proxy. Moreover, F30 is available since March 1957 whereas Mg II only since November 1978. Thus for long-term studies of yearly foF2 at middle latitudes F30 is the most suitable solar activity proxy.

Change of the dependence of foF2 on solar activity proxies from 1976-1995 to 1996-2014 appears to be of solar origin; it is related to changes of interdependences among solar proxies between the first and second periods.

How to cite: Laštovička, J.: F30 is the most suitable solar activity proxies for foF2 at middle latitudes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2039, https://doi.org/10.5194/egusphere-egu23-2039, 2023.

EGU23-2325 | Orals | ST3.1

Dual boundary coordinates in polar magnetosphere-ionosphere studies 

Angeline Burrell, Gareth Chisham, and Kate Zawdie

The high latitude ionosphere, which coincides with the Arctic and Antarctic regions, is a complex region that is strongly coupled with the magnetosphere, neutral atmosphere, and the solar wind.  The high latitude ionosphere may be divided into two regions based on the portion of the magnetosphere to which the ionosphere is connected.  The most poleward region, the polar cap, is the area characterized by open magnetic field lines that connect directly to the interplanetary magnetic field (IMF) instead of closing in the opposite hemisphere.  Within the polar cap, ionospheric plasma moves anti-sunward and HF propagation paths between a transmitter and receiver may occur through reflection in either the E region or F region of the ionosphere. Just equatorward of the polar cap is the auroral oval, a region that experiences high amounts of particle precipitation and energy transfer between the magnetosphere and ionosphere along closed magnetic field lines.  The equatorward edge of the auroral oval marks the beginning of the mid-latitudes.  Defining high latitude coordinates relative to these physically significant boundaries has implications for statistical studies, modeling applications, and research combining magnetospheric and ionospheric data.  This study explores the impact of using single or multiple boundaries on such high latitude research efforts, and presents a tool to aid this research.

How to cite: Burrell, A., Chisham, G., and Zawdie, K.: Dual boundary coordinates in polar magnetosphere-ionosphere studies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2325, https://doi.org/10.5194/egusphere-egu23-2325, 2023.

EGU23-2700 | Orals | ST3.1

Rapidly changing ionospheric structures inferred the by International LOFAR Telescope 

Alan Wood, Gareth Dorrian, Ben Boyde, Richard Fallows, and Maaijke Mevius

The Low Frequency Array (LOFAR) is designed to observe the early universe at radio wavelengths. When radio waves from a distant astronomical source traverse the ionosphere, structures in the plasma affect the signal. The high temporal resolution available (~10 ms), the large range of frequencies observed (10-80 MHz & 120-240 MHz) and the large number of receiving stations (currently 52 across Europe) mean that LOFAR can observe the effects of the midlatitude ionosphere in an unprecedented level of detail.

The observational programme LT16_002 began in September 2021 and observations from the first 15 months of this programme are used to investigate ionospheric structures. A variety of patterns in the received signal intensity have been observed. Some of these appear to be similar to features reported previously, such as Spectral Caustics seen in solar observations (Koval et al., 2017) using the Nançay Decametric Array, as well as observations inferred from LOFAR of Travelling Ionospheric Disturbances (TIDs) at large- and medium-scales (Fallows et al., 2020), small scale TIDs (Boyde et al., 2022) and sporadic E (Wood et al., 2022). Other structures appear to be previously unreported. Collectively, we refer to these structures as Radio Alteration Features (RAFs).

In order to investigate the occurrence and origin of RAFs, 1092 hours of observations from LT16_002 were analysed. If the intensity of the received signal rose to 20% above the median value for the observation in a given hour then, within this study, this hour was classified as containing a RAF. RAFs were observed in 382 hours of observations. RAFs are primarily a night-time phenomenon and are more common in summer. They do not appear to have a statistically-significant relationship to geomagnetic activity as measured by a variety of geomagnetic indices, but there is some evidence that they are more common during times of enhanced solar activity or when a CME encounters the Earth.

Work on a measure of the strength of the RAFs is underway using the amplitude scintillation index S4. New observations from LT16_002 mean that the database is continually expanding. Comparisons of the climatology of RAFs to the climatology of other features, such as TIDs, is planned to give an insight into the driving processes. The latest developments in this work will be reported.

References

Boyde, B., Wood, A. G., Dorrian, G. D., Fallows, R. A., Themens, D. R., et al. (2022). Lensing from small-scale travelling ionospheric disturbances observed using LOFAR. J. Space Weather Space Clim. 12, 34. https://doi.org/10.1051/swsc/2022030.

Fallows, R. A., et al. (2020), A LOFAR Observation of Ionospheric Scintillation from Simultaneous Medium- and Large-scale Travelling Ionospheric Disturbances, J. Space Weather Space Clim. doi.org/10.1051/swsc/2020010.

Koval, A., et al. (2017), Traveling ionospheric disturbances as huge natural lenses: Solar radio emission focusing effect, J. Geophys. Res. Space Physics, 122, 9092–9101, doi:10.1002/2017JA024080.

Wood, A. G., Dorrian, G. D., Boyde, B. and Fallows, R. A. (2022), Terrestrial drivers of rapidly changing plasma structures observed with the International LOFAR Telescope, 3rd URSI AT-AP-RASC.

How to cite: Wood, A., Dorrian, G., Boyde, B., Fallows, R., and Mevius, M.: Rapidly changing ionospheric structures inferred the by International LOFAR Telescope, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2700, https://doi.org/10.5194/egusphere-egu23-2700, 2023.

EGU23-3716 | ECS | Orals | ST3.1

Modeling the ionospheric delayed response to solar rotation period changes in EUV radiation 

Rajesh Vaishnav, Christoph Jacobi, Erik Schmölter, Hanna Dühnen, Jens Berdermann, and Mihail Codrescu

The thermosphere-ionosphere system changes significantly on various temporal scales due to the forcings from solar and geomagnetic processes, and the lower atmosphere. The 27-day variation caused by solar rotation is one of the most important modulating factors in the ionosphere. A robust feature in this context is the ionospheric lag of about 1-2 days in ionospheric parameters such as total electron content (TEC) and F2 layer peak electron density with respect to solar variations at the 27-day solar rotation period. Here, the ionospheric TEC provided by the International GNSS Service (IGS) and the Coupled Thermosphere Ionosphere Plasmasphere electrodynamics (CTIPe) model were used to understand the delayed ionospheric response and the underlying physics. The O/N2 measurements from the imaging ultraviolet spectrograph Global-Scale Observations of the Limb and Disk (GOLD), the Global Ultraviolet Imager (GUVI), were also analyzed during the 2019-2021 period of low solar activity. The comparative study shows that the model successfully reproduces the delayed response of the ionosphere during low solar activity. The observed and modeled O/N2 ratio was found to be positively correlated with the solar EUV proxy (GOLD QEUV), with a lag of about 2 days, indicating a contribution to the ionospheric lag in TEC.
Furthermore, the CTIPe model simulations show 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., Berdermann, J., and Codrescu, M.: Modeling the ionospheric delayed response to solar rotation period changes in EUV radiation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3716, https://doi.org/10.5194/egusphere-egu23-3716, 2023.

EGU23-3911 | Posters virtual | ST3.1

Atmospheric gravity waves generated by solar wind high-speed stream Alfvén waves 

Paul Prikryl, David R. Themens, Jaroslav Chum, Shibaji Chakraborty, Robert G. Gillies, and James M. Weygand

Solar wind Alfvén waves in high-speed streams from coronal holes modulate dayside ionospheric convection and currents, including auroral electrojets [1]. They generate large- to medium-scale atmospheric gravity waves (AGWs) propagating globally from sources in the lower thermosphere both upward and downward [2,3]. In the upper atmosphere, the AGWs drive traveling ionospheric disturbances (TIDs) observed by the Super Dual Auroral Radar Network (SuperDARN), Poker Flat Incoherent Scatter Radar (PFISR), and the GNSS total electron content (TEC) mapping technique. The horizontal equivalent ionospheric currents are estimated from the ground-based magnetometer data using an inversion technique. In the lower atmosphere, the equatorward propagating AGWs with attenuated amplitudes can be amplified upon over-reflection in the troposphere. They can release conditional symmetric instability leading to slantwise convection, latent heat release and intensification of extratropical cyclones [4,5], which in turn are a source of AGWs/TIDs. Southeastward propagating TIDs that originate from cold fronts of intensifying extratropical cyclones are observed in the detrended TEC maps, and by the multipoint and multifrequency continuous Doppler sounders in Czechia. Ray tracing AGWs in a model atmosphere supports the observations.

[1] Prikryl P., et al., Ann. Geophys., 40, 619–639, 2022. doi.org/10.5194/angeo-40-619-2022
[2] Mayr H.G., et al., Space Sci. Rev. 54, 297–375, 1990. doi:10.1007/BF00177800
[3] Prikryl, P., et al., Ann. Geophys. 23, 401–417, 2005. doi.org/10.5194/angeo-23-401-2005
[4] Prikryl P., et al., Ann. Geophys. 27, 31–57, 2009. doi:10.5194/angeo-27-31-2009
[5] Prikryl P., et al., J. Atmos. Sol.-Terr. Phys. 171, 94–10, 2018. doi:10.1016/j.jastp.2017.07.023

How to cite: Prikryl, P., Themens, D. R., Chum, J., Chakraborty, S., Gillies, R. G., and Weygand, J. M.: Atmospheric gravity waves generated by solar wind high-speed stream Alfvén waves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3911, https://doi.org/10.5194/egusphere-egu23-3911, 2023.

EGU23-5590 | Posters on site | ST3.1

Exploration of the divergent effects of CMEs on low Earth orbiting satellites – current status of the project ESPRIT 

Sandro Krauss, Sofia Kroisz, Lukas Drescher, Manuel Scherf, Helmut Lammer, Manuela Temmer, and Andreas Strasser

With a view to the rising solar cycle 25 (maximum expected to be 2025/26) the solar activity level will steadily increase, which implies that the Earth’s atmosphere is expanding, and higher drag forces are acting on near-Earth satellites. To avoid earlier re-entries of satellite missions it is mandatory to monitor and at best accurately forecast extreme space weather conditions. We investigated different kinds of coronal mass ejections (CMEs) which had divergent effects on the trajectories of low Earth orbiting satellites. A special focus is given to the interaction of sequentially occurring CME events (e.g., 2021/11/03). So called multiple events lead to multiple field compressions and a capable to increase the severity of the impact on the near-Earth environment. 

Furthermore, we investigated the predominant chemical composition of Earth atmosphere based on satellite observation from the TIMED satellite (SEE, SABER). Additionally, we explored identified diverging behavior of various CMEs by simulating the events with the Kompot code, a 1D first-principles hydrodynamic upper atmosphere model. We found that for some of the selected events the atmospheric exobase and density profile shows some significant expansion mainly based on the increased XUV flux from the Sun. However, we also found that the sole effect of the incident XUV flux might only partially explain NO production, and the structure of the upper atmosphere. 

How to cite: Krauss, S., Kroisz, S., Drescher, L., Scherf, M., Lammer, H., Temmer, M., and Strasser, A.: Exploration of the divergent effects of CMEs on low Earth orbiting satellites – current status of the project ESPRIT, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5590, https://doi.org/10.5194/egusphere-egu23-5590, 2023.

EGU23-6633 | ECS | Posters on site | ST3.1

Topside ionosphere effective plasma scale height characterization through CSES-01 satellite Langmuir Probes observations 

Michael Pezzopane, Alessio Pignalberi, Igino Coco, Giuseppe Consolini, Giulia D'Angelo, Paola De Michelis, Fabio Giannattasio, Mirko Piersanti, and Roberta Tozzi

The topside ionosphere embraces the region extending from the F2-layer electron density peak to the overlying plasmasphere. In this region the electron density monotonically decreases at a vertical rate driven by the plasma scale height, which in turn depends on both the plasma chemical composition and the physical state. Since an accurate and thorough knowledge of the plasma chemical and physical properties at these altitudes is not available with the required spatial and temporal coverage, an effective plasma scale height is usually inferred from topside electron density measurements and used for empirical modelling purposes.

In this work, we aim at characterizing the effective plasma scale height (H0) above the F2-layer peak  through in-situ electron density (Ne) observations by Langmuir Probes (LPs) on-board the China Seismo-Electromagnetic Satellite (CSES-01). Additional information is given by the International Reference Ionosphere (IRI) model. CSES-01 is a sun-synchronous satellite flying with an orbital inclination of 97.4°, an altitude of ~500 km, and descending and ascending nodes are at ~14 local time (LT) and ~02 LT, respectively. Calibrated CSES-01 LPs Ne data recorded in the years 2019-2021 provides the information in the topside ionosphere, while IRI provides the Ne values at the F2-layer peak (NmF2) for the same time, latitude, and longitude sounded by CSES-01. These two Ne set of values are used as anchor points to infer H0 through the topside representation given by the NeQuick model. By exploiting the CSES-01 dataset for the years 2019-2021 we deduced the global H0 behavior for daytime (~14 LT) and nighttime (~02 LT) conditions, for low solar activity conditions. Results obtained with CSES-01 observations are compared and validated with corresponding ones provided by COSMIC-1 radio occultation measurements for similar diurnal and solar activity conditions.

How to cite: Pezzopane, M., Pignalberi, A., Coco, I., Consolini, G., D'Angelo, G., De Michelis, P., Giannattasio, F., Piersanti, M., and Tozzi, R.: Topside ionosphere effective plasma scale height characterization through CSES-01 satellite Langmuir Probes observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6633, https://doi.org/10.5194/egusphere-egu23-6633, 2023.

EGU23-6707 | Posters on site | ST3.1

Multiinstrumental observations of traveling ionospheric disturbances over Europe 

Dalia Buresova, Sergii V. Panasenko, Kateryna D. Aksonova, Oleksandr V. Bogomaz, Taras G. Zhivolup, and Alexander V. Koloskov

The paper presents results of the analysis of the TID activity and changes in the regular ionospheric variability observed over central and eastern Europe during geomagnetically quiet days, and during CME and CIR/HSSS-related storms. We analyzed main ionospheric parameters retrieved from manually scaled ionograms obtained at several central and eastern European locations and incoherent scatter radar data (Kharkiv, Ukraina). Large scale traveling ionospheric disturbance (LSTIDs) are thought to be mostly originated in the auroral zone in consequence of increased geomagnetic activity. Although there have been numerous studies of TIDs, current knowledge is often based on observing only limited set of parameters and two-dimensional characteristics (for example, total electron content by GNSS receivers or airglow brightness by all-sky imagers). Incoherent scatter technique enables simultaneous studies of altitudinal characteristics of TIDs in several parameters like electron density, electron and ion temperature and plasma drift, thus providing important information needed to investigate TIDs, their propagation and consider probable association of TIDs with their sources. This technique also yields all components of wave vector, provided that the radar has the ability to operate in multi-beam mode. In order to obtain quantitative information on the likeliness and morphology of the passage of LSTIDs over Europe at about 40 events were examined lasting between 8 and 24 hours each. In this paper we focused mainly on a couple of geomagnetic disturbances (depending on the incoherent scatter radar data availability). Most of the observed storm-related TIDs had periods of 60-180 min (LSTIDs). During the analyzed storms we also observed extraordinary spreads and plasma bubbles at the F region heights.

How to cite: Buresova, D., Panasenko, S. V., D. Aksonova, K., Bogomaz, O. V., Zhivolup, T. G., and Koloskov, A. V.: Multiinstrumental observations of traveling ionospheric disturbances over Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6707, https://doi.org/10.5194/egusphere-egu23-6707, 2023.

EGU23-8308 | Posters on site | ST3.1

Doppler shifted auroral Lyman-alpha spectra observed by DMSP/SSUSI 

Kan Liou, Larry Paxton, Yongliang Zhang, and Robert Schaefer

Proton auroras are produced by energetic protons that precipitate, undergo charged exchange, and subsequently emit hydrogen lines before they are ionized again. When viewed from space, the spectral shape of proton auroras is expected to shift to longer wavelengths (red shift) due to the Doppler effect. Reports on space-based observations of Doppler shift of hydrogen Lyman-alpha spectral line associated with auroral proton precipitation are still rare. The Special Sensor Ultraviolet Spectrographic Imager (SSUSI) on board the Defense Meteorological Satellite Program (DMSP) series is a line scanning imaging spectrograph covering the far ultraviolet (FUV) spectrum from ~112 to 185 nm with 160 spectral bins. Under the spectragraph mode, SSUSI is supposed to be able to provide information about proton auroral precipitation. Here we present results from our first attempt to extract Doppler shift of Lyman-alpha spectral line of Hydrogen from the SSUSI data. We show red-shifted Lyman-alpha spectra observed by SSUSI whenever the DMSP satellite traverses the auroral oval, especially during geomagnetic active time. In general, a larger red shift appears in the nightside than dayside oval crossing and in the equatorward than poleward half of the oval. These are generally consistent with in situ auroral particle observations reported previously. Thus DMSP/SSUSI provides an alternative means to monitoring the energetic of proton precipitation.

How to cite: Liou, K., Paxton, L., Zhang, Y., and Schaefer, R.: Doppler shifted auroral Lyman-alpha spectra observed by DMSP/SSUSI, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8308, https://doi.org/10.5194/egusphere-egu23-8308, 2023.

EGU23-8852 | ECS | Orals | ST3.1

Global ionospheric response to a periodic sequence of HSS/CIR events during the 2007-2008 solar minimum 

Catalin Negrea, Costel Munteanu, and Marius Echim

We describe the global ionospheric impact of high-speed solar wind streams/corotating interaction regions (HSS/CIR), using a series of ten such events identified between December 1st 2007 and April 29th 2008. In the frequency domain they are characterized by the main spectral peaks corresponding to 27, 13.5, 9 and 6.75 days. The spectra of solar wind magnetic field, speed and proton density, as well as those of the geomagnetic indices AE and SYM-H are solely dominated by these features. By contrast, the ionospheric NmF2 and to a lesser extent the hmF2 spectra have a much more complex structure, with secondary peaks adding to or replacing the main ones. We argue that this is evidence of the nonlinear nature of the magnetosphere-ionosphere coupling, highlighted particularly in the NmF2 ionospheric response. Additionally, we show that hmF2 is more closely correlated than NmF2 to all parameters describing the solar wind and geomagnetic activity. Finally, the ionospheric response shows higher correlation with Bz than any other solar wind parameter, and higher with SYM-H than AE, indicating that for the low-frequency part of the spectrum, high-latitude Joule heating and particle precipitation play a secondary role to that of prompt penetration electric fields in dictating the ionospheric response to geomagnetic activity, in the case of this sequence of HSS/CIR events.

Results are also included in the paper:

Negrea et al. 2021 -  Global Ionospheric Response to a Periodic Sequence of HSS/CIR Events During the 2007–2008 Solar Minimum (https://doi.org/10.1029/2020JA029071).

How to cite: Negrea, C., Munteanu, C., and Echim, M.: Global ionospheric response to a periodic sequence of HSS/CIR events during the 2007-2008 solar minimum, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8852, https://doi.org/10.5194/egusphere-egu23-8852, 2023.

EGU23-9013 | Posters on site | ST3.1

PITHIA-NRF offers Trans-national access to European upper atmosphere research facilities 

Ingemar Häggström and Maria Mihalikova

One of the objectives of the PITHIA-NRF project is to provide effective and convenient access to the best European research facilities for observations of the upper atmosphere. The individual PITHIA-NRF nodes provide access to key experimental and data processing facilities for studies and modeling of physical processes acting in the Earth’s plasmasphere, ionosphere and thermosphere. The facilities connected to the nodes are geographically distributed over Europe, as well as internationally, and their expertise and dedication span over a wide range of topics within the research area. This variety of expertise and techniques, all with the purpose of studying specific parts of the ionosphere-thermosphere-plasmasphere (ITP), allows for common ground and a platform for a better understanding of the many different complex couplings and interactions within ITP as well as between ITP and the magnetospheric/space environment.

The access to the nodes is organised through the Trans-National Access (TNA) programme and provides an opportunity for researchers and other users to execute and carry out their own projects at one of the twelve PITHIA-NRF research facilities. Users can request either physical access (a one-week visit at the node with support at the site) or remote access (one-month access from a distance with weekly support). Users with granted projects will learn how to work with the facilities during the complete access cycle, from setting up a campaign to the collection, analysis and finally exploitation of data with the help of tools and services provided by PITHIA-NRF via the e-science centre. There is also a possibility of virtual access - typically referring to access to data and digital tools. There are no restrictions to the number of simultaneous users, and no selective process is needed for this type of Access. PITHIA-NRF e-science centre is currently under development, and it will be offering more and more tools with time. Access to the TNA programme can be requested by scientific users from academia, Small and Medium Enterprises, large companies and public organizations by proposing a scientific project and applying through the PITHIA-NRF website: https://pithia-nrf.eu/

How to cite: Häggström, I. and Mihalikova, M.: PITHIA-NRF offers Trans-national access to European upper atmosphere research facilities, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9013, https://doi.org/10.5194/egusphere-egu23-9013, 2023.

EGU23-9536 | Orals | ST3.1 | Highlight

Magnetic storms during the space age: Occurrence and relation to varying solar activity 

Kalevi Mursula, Timo Qvick, Lauri Holappa, and Timo Asikainen

We review here the occurrence of magnetic storms during the space age (1957 - 2021), as observed by two storm indices, the Dst index and the Dxt index. We study the solar sources of storms, describe the dramatic changes in the different types of storms during the space age, and explain these changes in terms of the long-term change of solar activity and solar magnetic fields during the decline of the Modern Grand Maximum.

We find 2526/2743 magnetic storms in the Dxt/Dst index, out of which 45% are weak (-50 nT <  Dxt/Dst ≤ -30 nT), 40% moderate (-100 nT < Dxt/Dst ≤ -50 nT), 12% intense (200 nT < Dxt/Dst ≤ -100 nT) and 3% major (Dxt/Dst ≤ -200 nT) storms. Occurrence of storms in space age follows the slow decrease of sunspot activity and the related change in solar magnetic structure. We quantify the sunspot - CME storm relation in the five cycles of space age. We explain how the varying solar activity changes the structure of the heliospheric current sheet (HCS) and how this affects the HSS/CIR storms.

Space age started with a record number of storms in 1957 - 1960, with roughly one storm per week. Solar polar fields attained their maximum in cycle 22, which led to an exceptionally thin HCS, and a space age record of large HSS/CIR storms in 1990s. In the minimum of cycle 23, for the only time in space age, CME storm occurrence reduced below that predicted by sunspots. Weak sunspot activity since cycle 23 has weakened solar polar fields and widened the HCS, which has decreased the occurrence of large and moderate HSS/CIR storms. Moreover, because of the wide HCS, the Earth has spent 50% of its time in slow solar wind since cycle 23. The wide HCS has also made large and moderate HSS/CIR storms to occur in the early declining phase in recent cycles, while in the more active cycles 20-22 they occurred in the late declining phase.

How to cite: Mursula, K., Qvick, T., Holappa, L., and Asikainen, T.: Magnetic storms during the space age: Occurrence and relation to varying solar activity, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9536, https://doi.org/10.5194/egusphere-egu23-9536, 2023.

EGU23-10080 | ECS | Posters on site | ST3.1

Three-dimensional modeling of barium cloud's expansion in the E and F regions: Applying for BROR mission. 

Yoshihiro Yokoyama and Tima Sergienko

The chemical release at an ionospheric altitude allows us to investigate the plasma processes in the ionosphere-magnetosphere system. The numerical models of the expansion of the artificial plasma clouds produced by the chemical release have been developed. Previous works revealed that, for a barium release with no directional velocity in the uniform background, the neutral barium cloud expands radially, while the ionized barium (Ba+) cloud produced by photoionization of the neutral cloud expands into an elliptic structure along the direction of the magnetic field. And they also revealed that the background ionospheric and initial release conditions primarily affect the cloud’s behavior. Barium Release Optical and Radio rocket (BROR) mission plans to conduct several barium releases at different ionospheric altitudes between 120 and 180 km, which are much lower than past experiments, aiming to study small-scale processes and structure in the auroral ionosphere by means of an active modification of the ionosphere. Since the atmospheric composition of ion and neutral spices and their parameters vary significantly around the BROR target region, i.e., from the E region to the bottom of the F region, we took into these altitudinal differences in our model. We revealed that the altitudinal difference contributes significantly to the Ba+ cloud’s expansion, especially with no background and release velocity, producing a teardrop shape. We also found that the Ba+ cloud at lower altitudes expands slowly, confining to a relatively small area due to the higher collision frequency. In comparison, the Ba+ cloud at a higher altitude stretches faster along the magnetic field and ends up with larger radii due to the lower collision frequency and higher diffusion rate. In this presentation, we show numerical results for the different release conditions at several altitudes in the E and F region and discuss the effects of different release conditions at various altitudes.

How to cite: Yokoyama, Y. and Sergienko, T.: Three-dimensional modeling of barium cloud's expansion in the E and F regions: Applying for BROR mission., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10080, https://doi.org/10.5194/egusphere-egu23-10080, 2023.

EGU23-10750 | Orals | ST3.1

Study the July 7-8 2022 geomagnetic storm event using the MAGE simulation 

Qian Wu, Wenbin Wang, Dong Lin, Liying Qian, Chaosong Huang, and Yongliang Zhang

The recent July 7-8 2022 event presents a good opportunity to examine many aspects of the geomagnetic event with a new model and available satellite missions.   We will focus on the penetrating electric field.    Using a state of art magnetosphere and ionosphere coupled model called MAGE (Multiscale Atmosphere-Geospace Environment) ,   we are able to simulate fast reactions of the ionosphere to the dynamic inputs from the magnetosphere.     We have used this model to study some winter events.   The July 7-8 summer event presents different ionosphere conditions in the northern hemisphere.   Taking advantage of the availability of the COSMIC 2 ionosphere data,  we will also examine the negative phase during this event. 

 
 

How to cite: Wu, Q., Wang, W., Lin, D., Qian, L., Huang, C., and Zhang, Y.: Study the July 7-8 2022 geomagnetic storm event using the MAGE simulation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10750, https://doi.org/10.5194/egusphere-egu23-10750, 2023.

EGU23-13577 | ECS | Posters on site | ST3.1

Using convoluted distributions to infer auroral brightness during sunlit conditions 

Jens Christian Hessen, Jone Peter Reistad, and Karl Magnus Laundal

Sunlight makes it difficult to measure the aurora. We use data obtained by the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) onboard the Defense Meteorological Satellite Program’s (DMSP) F16-19 satellites to quantify the auroral intensities during sunlit conditions. We use Environmental Disk Radiance (EDR) Aurora data product from the SSUSI-team, where the dayglow is already subtracted. The error in the dayglow-subtraction is proportional to the strength of the dayglow and represents an uncertainty in the observations. We characterize the auroral intensity and the dayglow part of the signal by combining multiple observations during similar solar illumination, and magnetic local time/latitude. By fitting convolutions of symmetric (dayglow-error) and fat-tailed distributions (aurora) on data from many years, it might be possible to separate the signal from the aurora. By comparing this to the regular methods of estimating auroral intensity (mean/median) we will assess the usefulness and importance of this method. We examine the validity of our method by evaluating the fits of the convoluted distributions.

How to cite: Hessen, J. C., Reistad, J. P., and Laundal, K. M.: Using convoluted distributions to infer auroral brightness during sunlit conditions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13577, https://doi.org/10.5194/egusphere-egu23-13577, 2023.

EGU23-15390 | ECS | Orals | ST3.1

Modelling of Storm-Time Relative Total Electron Content using a Fully Connected Neural Network 

Marjolijn Adolfs, Mainul Hoque, and Yuri Shprits

During geomagnetic storms the total electron content (TEC) can dramatically change compared to quiet-time conditions. Therefore, it is still a challenging task for ionospheric models to predict accurately during storm times. In this work, the relative TEC with respect to the preceding 27-day median TEC is predicted, during storm time for the European region (with longitudes 30°W–50°E and latitudes 32.5°N–70°N) using machine learning techniques. A fully connected neural network (NN) is proposed that uses the 27-day median TEC (referred to as median TEC), latitude, longitude, universal time, storm time, solar radio flux index F10.7, global storm index SYM-H and geomagnetic activity index Hp30 as inputs and the output of the network is the relative TEC. The model was trained with storm-time relative TEC data, computed with UQRG global ionosphere maps (GIMs), from the time period of 1998 until 2019 (2015 is excluded) and contains 365 storms. The model was tested with unseen storm data from 33 storm events during 2015 and 2020. The storm-time relative TEC model’s predictions showed the seasonal behavior of the storms including positive and negative storm phases during winter and summer, respectively, and a mixture of both phases was seen during equinoxes. The relative TEC was converted to the actual TEC, using the median TEC, and was compared to the Neustrelitz TEC model (NTCM) and a NN-based quiet-time TEC model. The storm model outperforms the NTCM by 1.87 TEC units (TECU) and the quiet-time model by 1.34 TECU during storm time.

How to cite: Adolfs, M., Hoque, M., and Shprits, Y.: Modelling of Storm-Time Relative Total Electron Content using a Fully Connected Neural Network, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15390, https://doi.org/10.5194/egusphere-egu23-15390, 2023.

EGU23-16331 | ECS | Posters on site | ST3.1

Total Electron Content evolution during the 27 February 2014 storm over the Iberian Peninsula and Northern Africa 

Saioa A. Campuzano, Yenca Migoya-Orué, Sandro M. Radicella, Fernando Delgado-Gómez, Miguel Herraiz, and Gracia Rodríguez-Caderot

In this work Total Electron Content (TEC) during the moderate geomagnetic storm of 27 February 2014 over the Iberian Peninsula and Northern Africa is analysed. The data used are coming from GNSS derived TEC and ROTI from several receiver stations from Spain, Portugal and Morocco. Maps of TEC are developed to study its evolution before, during and some days after the main phase of the storm. This study shows that before the storm, i.e. during quiet geomagnetic conditions, a northern crest of the Equatorial Ionosphere Anomaly (EIA) is located in Western North Africa with low gradients and values of TEC. During the main period of the storm, this northern crest of the EIA is also located in the Western North Africa with larger gradients that affect the southern part of the Iberian Peninsula. These gradients are present both in latitude and longitude. They are observed exclusively over this region but not seen in the rest of Southern Europe. In addition, increased values of ROTI from GNSS stations located in Southern Spain are also found during the storm, but not observed northwards and eastwards of that region. Since the Iberian Peninsula is located in a mid-latitude area not expected to be influenced by the EIA, these findings seem to indicate that the Southern part of the Peninsula could be influenced by the EIA during disturbed geomagnetic conditions.

How to cite: Campuzano, S. A., Migoya-Orué, Y., Radicella, S. M., Delgado-Gómez, F., Herraiz, M., and Rodríguez-Caderot, G.: Total Electron Content evolution during the 27 February 2014 storm over the Iberian Peninsula and Northern Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16331, https://doi.org/10.5194/egusphere-egu23-16331, 2023.

A FORMOSAT-5 satellite was launched on 25 August 2017 CST into a 98.28° inclination sun-synchronous circular orbit at 720 km altitude along the 1030/2230 local time sectors.  The orbital coverage provides a great opportunity to survey terrestrial ionosphere from equatorial to polar region every two days.  Advanced Ionospheric Probe (AIP) is a piggyback science payload developed by National Central University for the FORMOSAT-5 satellite to measure ionospheric plasma concentrations, velocities, and temperatures.  It is also capable of measuring ionospheric plasma density irregularities at a sample rate up to 8,192 Hz over a wide range of spatial scales.  In this poster, global ion density distributions measured by FORMOSAT-5/AIP in the pre-midnight sector can be averaged monthly and seasonally from in-situ measurement since November 2017.  Equatorial wave-4 patterns, plasma depletion bays, and mid-latitude plasma density enhancement are clearly observed from the distributions and varied with season and solar cycle.  It is adversely indicated that FORMOSAT-5/AIP can provide high quality data to identify long-term ionospheric ion density variations.

How to cite: Chao, C.-K.: Global Ion Density Distributions Observed by Advanced Ionospheric Probe Onboard FORMOSAT-5 Satellite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17033, https://doi.org/10.5194/egusphere-egu23-17033, 2023.

EGU23-17588 | Orals | ST3.1

NASA’s Geospace Dynamics Constellation (GDC) mission: a multi-spacecraft mission to explore the ionosphere-thermosphere 

Douglas Rowland, Katherine Garcia-Sage, Larry Kepko, Jared Bell, Laila Andersson, Phillip Andersson, Mark Moldwin, Daniel Gershman, and Mehdi Benna

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 conegurations 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 poster presents GDC's current status, measurement capabilities, sampling scheme, and model development efforts and show how GDC will et into the larger Heliophysics ecosystem, by 1) obtaining critically needed scientiec 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.

How to cite: Rowland, D., Garcia-Sage, K., Kepko, L., Bell, J., Andersson, L., Andersson, P., Moldwin, M., Gershman, D., and Benna, M.: NASA’s Geospace Dynamics Constellation (GDC) mission: a multi-spacecraft mission to explore the ionosphere-thermosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17588, https://doi.org/10.5194/egusphere-egu23-17588, 2023.

EGU23-1919 | ECS | Orals | ST3.3

Kinetic Modeling of Ion Outflows with Observations from the VISIONS-1 Sounding Rocket 

Robert Albarran and Matthew Zettergren

Plasma escape from the high-latitude ionosphere (ion outflow) serves as a significant source of heavy plasma to magnetospheric plasma sheet and ring current regions. Outflows alter mass density and reconnection rates, hence global responses of the magnetosphere. The VISIONS-1 (VISualizing Ion Outflow via Neutral atom imaging during a Substorm) sounding rocket was launched on Feb. 7, 2013 at 8:21 UTC from Poker Flat, Alaska, into an auroral substorm with the objective of identifying the drivers and dynamics of nightside ion outflow at altitudes where it is initiated, below 1000 km. Energetic ion data from the VISIONS-1 polar cap boundary crossing show evidence of an ion "pressure cooker'' effect whereby ions energized via transverse heating in the topside ionosphere travel upward and are impeded by a parallel potential structure at higher altitudes.

A new fully kinetic model is constructed from first principles which traces large numbers of individual O+ ion macro-particles along curved magnetic field lines, using a guiding-center approximation, in order to facilitate calculation of ion distribution functions and moments. Particle forces in a three-dimensional global Cartesian coordinate system include mirror and parallel electric field forces, a self-consistent ambipolar electric field, and a parameterized source of ion cyclotron resonance (ICR) wave heating, thought to be central to the transverse energization of ions. The model is initiated with a steady-state ion density altitude profile and Maxwellian velocity distribution and multiple particle trajectories are advanced via a direct simulation Monte Carlo (DSMC) scheme. This document outlines the design and implementation of the kinetic outflow model and shows applications of simulated outflows representative of conditions observed during the VISIONS-1 campaign. This project provides quantitative means to interpret VISIONS-1 data and related remote sensing approaches to studying ion outflows and serves to advance our understanding of the drivers and particle dynamics in the auroral ionosphere and to improve data analysis for future sounding rocket and satellite missions.

How to cite: Albarran, R. and Zettergren, M.: Kinetic Modeling of Ion Outflows with Observations from the VISIONS-1 Sounding Rocket, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1919, https://doi.org/10.5194/egusphere-egu23-1919, 2023.

EGU23-2276 | Posters on site | ST3.3

The balance between turbulent and convection-driven plasma vorticity in the Earth’s ionosphere 

Gareth Chisham and Mervyn Freeman

Measurements of ionospheric flow vorticity can be used for studying ionospheric plasma transport processes, such as convection and turbulence, over a wide range of spatial scales. Here, we present the spatial variation across the northern hemisphere high-latitude ionosphere of probability density functions (PDFs) of ionospheric vorticity as measured by the Super Dual Auroral Radar Network (SuperDARN) over a six-year interval (2000-2005 inclusive). These PDFs are subdivided for different polarities of the By component of the Interplanetary Magnetic Field (IMF), which allows the separation of the observed PDFs into two distinct components. These components relate to: (1) The large-scale ionospheric convection flow driven by magnetic reconnection, and (2) Meso- and small-scale processes such as turbulence. The convection vorticity PDFs are single-sided and well fit by Weibull distributions, whereas the turbulence vorticity PDFs are double-sided and symmetric, and are well fit by q-exponential distributions. Both the observed model distributions can be understood in the framework of solutions of the stationary Fokker-Planck equation for different environmental plasma conditions.

How to cite: Chisham, G. and Freeman, M.: The balance between turbulent and convection-driven plasma vorticity in the Earth’s ionosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2276, https://doi.org/10.5194/egusphere-egu23-2276, 2023.

EGU23-2408 | Posters on site | ST3.3 | Highlight

DRivers and Impacts of Ionospheric Variability with EISCAT_3D (DRIIVE) 

Andrew Kavanagh and the DRIIVE Collaboration

EISCAT_3D provides an unprecedented opportunity to study key processes in the auroral latitude ionosphere across multiple scales.

DRIIVE exploits the unique capabilities of EISCAT_3D to identify the key atmospheric and space weather drivers of variability in the ionosphere-thermosphere system, and to determine the impact of small-scale processes on thermospheric density and the satellite orbital environment.

The project will identify the effects of lower atmosphere forcing and changes to local composition, while measuring energy input from space weather processes.  Findings on the impact of small-scale changes will be fed into the next generation of large-scale models, working closely with stakeholders across the space and atmosphere communities. DRIIVE involves 24 scientists from 19 UK institutes, partnering with international colleagues from 9 other countries.

This poster provides an overview of the project science, key data sets and techniques that will be applied to advance our understanding of multi-scale processes in the ionosphere.

How to cite: Kavanagh, A. and the DRIIVE Collaboration: DRivers and Impacts of Ionospheric Variability with EISCAT_3D (DRIIVE), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2408, https://doi.org/10.5194/egusphere-egu23-2408, 2023.

EGU23-2504 | ECS | Posters on site | ST3.3

The impact of solar flare induced ionospheric disturbances on 27-day signatures in the T/I-system: preliminary results 

Erik Schmölter, Hanna Dühnen, and Jens Berdermann

Changes in solar activity are dominant drivers of long- and short-term variations in the upper atmosphere, which can affect each other through complex processes. Regular signatures in the ionosphere are caused, for example, by the 27-day solar rotation period and may be described with a delay of 1 to 2 days in addition to the respective amplitude. Such signatures and the associated delayed response of the ionosphere are influenced by several long-term variations (e.g., seasonal variations or 11-year solar cycle) as described in preceding studies. Here, we present the influence of solar flares on the ionospheric 27-day signatures providing a first insight into the interactions with short-term perturbations. Therefore, we present the response of different thermospheric and ionospheric parameters during X-class solar flare influenced 27-day signatures. We show in particular how the occurrence of solar flares can change accumulation processes and the resulting delay. The observed changes are especially dependent on the phase of the 27-day period in which the solar flares occur. The longest delays are observed for solar flares occurring during the ascending phase of the 27-day solar rotation period. The results are discussed in respect to preceding studies. Finally, we provide an outlook on a possible extension of the analysis by including M-class solar flares as well as additional space weather data sets and modeling results.

How to cite: Schmölter, E., Dühnen, H., and Berdermann, J.: The impact of solar flare induced ionospheric disturbances on 27-day signatures in the T/I-system: preliminary results, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2504, https://doi.org/10.5194/egusphere-egu23-2504, 2023.

EGU23-2899 | Orals | ST3.3 | Highlight

Understanding storm-time multi-scale ionospheric structures at mid-latitudes 

Ercha Aa, Shun-Rong Zhang, Philip Erickson, Anthea Coster, and Larisa Goncharenko

The storm-time mid-latitude ionosphere is an important interface in the global geospace dynamic system, which is characterized by energy and momentum ingests at the auroral/polar latitudes. This interface is affected by these high-latitude processes while being adjacent to expanded low-latitude electrodynamic/dynamic disturbances.  In particular, the mid-latitude and subauroral ionosphere can exhibit far more complicated multi-scale density/flow structures and disturbances than might otherwise be expected during geospace storms, such as large-scale and medium-scale traveling ionospheric disturbances (TIDs), storm-enhanced density (SED) plume, and subauroral polarization stream (SAPS). This presentation will describe some recent storm-time observations of these multi-scale ionospheric structures as well as discuss the underlying magnetosphere-ionosphere-thermosphere drivers. These observations provide some new scenarios to advance the current understanding of mid-latitude and subauroral dynamic processes at both large-scale and meso-scale levels.

How to cite: Aa, E., Zhang, S.-R., Erickson, P., Coster, A., and Goncharenko, L.: Understanding storm-time multi-scale ionospheric structures at mid-latitudes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2899, https://doi.org/10.5194/egusphere-egu23-2899, 2023.

EGU23-3306 | ECS | Posters on site | ST3.3

Can Throat Auroras Create Polar Cap Patches? 

Duan Zhang, Qinghe Zhang, Kjellmar Oksavik, Tong Xu, Zanyang Xing, Larry Lyons, Desheng Han, Hongbo Zhang, Yuzhang Ma, Zejun Hu, Jianjun Liu, Yong Wang, and Xiangyu Wang

Throat auroras and polar cap patches are common phenomena in the polar ionosphere. An observation campaign was organized, with all-sky imagers at Yellow River Station in Ny-Ålesund in Svalbard, the EISCAT Svalbard Radar, and coordinated low-altitude spacecraft observations. During periods of radial interplanetary magnetic field (IMF), observations showed that poleward moving throat auroras were linked to poleward moving ionization patches. Throat auroras are produced by soft-electron precipitation associated with dayside magnetic reconnection. The red line intensity of throat auroras is found to be correlated with dayside reconnection events. Dense plasma from lower latitudes was transported poleward by enhanced convection associated with the throat auroras to form electron density patches. This is potentially a new patch formation mechanism that is associated with throat auroras and magnetic reconnection for radial IMF. Moreover, the patches were found to E × B drift in the anti-sunward direction.

How to cite: Zhang, D., Zhang, Q., Oksavik, K., Xu, T., Xing, Z., Lyons, L., Han, D., Zhang, H., Ma, Y., Hu, Z., Liu, J., Wang, Y., and Wang, X.: Can Throat Auroras Create Polar Cap Patches?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3306, https://doi.org/10.5194/egusphere-egu23-3306, 2023.

EGU23-3387 | ECS | Posters on site | ST3.3

Spatio-Temporal Scales of Plasma Density in Topside Ionosphere 

Jaroslav Urbar, Luca Spogli, Antonio Cicone, Lasse Clausen, Yaqi Jin, Alan Wood, Elizabeth Donegan-Lawley, Lucilla Alfonsi, Claudio Cesaroni, Daria Kotova, Per Høeg, and Wojciech Miloch

Non-linear couplings of the Earth’s ionosphere with the geospace environment occur in a largely varying range of spatial and temporal scales. As some radio remote sensing techniques like GNSS measurements suffer from artificial radio frequency interference (RFI) at the smallest scales representing ionospheric scintillation, is it advantageous to have ionospheric scales observations based on in-situ measurements.

We investigated the variability of the in-situ plasma density and magnetic field measured by Swarm satellites creating the climatology of their scales by leveraging the Fast Iterative Filtering (FIF) technique.

FIF is able to provide a very fine time-frequency representation decomposing any non-stationary, nonlinear signals, into oscillating modes, called intrinsic mode components or functions (IMCs or IMFs), characterized by their specific frequency.

The results are obtained by time-integrating the instantaneous time-frequency representations, provided through the so-called “IMFogram”. These IMFograms have the potential to show the greater details of the scale sizes and their variations, illustrating the time development of the multi-scale processes during various disturbances of geospace.

How to cite: Urbar, J., Spogli, L., Cicone, A., Clausen, L., Jin, Y., Wood, A., Donegan-Lawley, E., Alfonsi, L., Cesaroni, C., Kotova, D., Høeg, P., and Miloch, W.: Spatio-Temporal Scales of Plasma Density in Topside Ionosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3387, https://doi.org/10.5194/egusphere-egu23-3387, 2023.

EGU23-4832 | ECS | Orals | ST3.3

Reaction of the Upper Atmosphere to the 27-d Solar Cycle - Comparison of CTIPe and TIE-GCM Simulations to Observations 

Hanna Dühnen, Rajesh Vaishnav, Erik Schmölter, and Christoph Jacobi

Solar EUV radiation is the dominant driver for upper atmosphere ionization. Ionospheric variations that affect radio signal propagation and thus affect technical systems such as satellite-based positioning systems. One significant time scale for the solar variability is the solar 27-day rotation period that causes a corresponding response in ionospheric observables like the height-dependent electron density (Ne) or the integrated total electron content (TEC). To enhance our understanding of the processes within the ionosphere we investigate a combination of observations and physical models, namely the Coupled Thermosphere Ionosphere Plasmasphere electrodynamics (CTIPe) model and the Thermosphere Ionosphere Electrodynamics General Circulation Model (TIE-GCM), are analyzed to identify differences in Ne, TEC data and ionized oxygen (O+ and O2+). Furthermore, the model results are compared to ground-based ionosonde Ne measurements with regard to the spatial and temporal response of the ionosphere to the 27-day solar rotation period. Modeled Ne correlates strongly with the observed Ne at mid-latitudes, but at low-latitudes the modeled TEC distribution follows the geomagnetic coordinates more strictly when compared to the observational data. Local TEC and F2 layer peak Ne are well represented by CTIPe, whereas TIE-GCM represents the global TEC and F2 layer peak height well.

How to cite: Dühnen, H., Vaishnav, R., Schmölter, E., and Jacobi, C.: Reaction of the Upper Atmosphere to the 27-d Solar Cycle - Comparison of CTIPe and TIE-GCM Simulations to Observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4832, https://doi.org/10.5194/egusphere-egu23-4832, 2023.

EGU23-7259 | Orals | ST3.3 | Highlight

Small scale ionospheric disturbances as seen by the LOFAR 

Maaijke Mevius and Kasia Beser

The LOFAR radio telescope consists of a large network of stations distributed across Europe, with a dense core in the east of the Netherlands. Each station consists of multiple antenna fields operating at frequencies between 20 and 80MHz and 110 and 240MHz. At these frequencies the ionosphere has a major impact on the astronomical observations, that needs to be corrected for.  This ionospheric calibration, at first order mainly a phase effect, provides valuable information about the ionospheric density variations above the telescope. We report on the use of the calibration solutions to extract the ionospheric information on structure, dominant direction and variability. In particular, we investigated the data recorded with the Dutch array, consisting of a core of 48 stations all within a 3 km diameter circle and another 14 remote stations with baselines up to 100 km, operating between 110 and 170 MHz.  The different baselines give access to different scales in the ionosphere. Furthermore, we present, for the same data, an imaging technique that allows direct imaging of larger scale gradients in the ionosphere.

How to cite: Mevius, M. and Beser, K.: Small scale ionospheric disturbances as seen by the LOFAR, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7259, https://doi.org/10.5194/egusphere-egu23-7259, 2023.

EGU23-8233 | Posters on site | ST3.3

Variations of the ionospheric total electron content over Portugal Continental and Azores 

Joana Pereira, Anna Morozova, Teresa Barata, and Tatiana Barlyaeva

The total electron content (TEC) variations over the Portuguese Mainland (Lisbon) and the Islands (Azores) are studied during the declining phase of the 24th solar cycle (December 2014 – November 2018). The two main goals of this study are (1) to understand main features of the TEC variability during quiet and disturbed days for the Portuguese territory and (2) to find similarities and differences in such features between the Continental (Iberian Peninsula area) and Oceanic (Azores area) parts.

Also, two methods to analyse TEC variations are used: TEC variations relative to a “quiet day” variation and the principal component analysis (PCA). Comparison of these methods and suggestions for the use of PCA to study TEC are made.

How to cite: Pereira, J., Morozova, A., Barata, T., and Barlyaeva, T.: Variations of the ionospheric total electron content over Portugal Continental and Azores, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8233, https://doi.org/10.5194/egusphere-egu23-8233, 2023.

Ionospheric irregularities are structures or fluctuations of plasma density having different scale sizes. These irregularities can disrupt radio waves and produce errors in space-based or ground-based technologies, which depend on the GNSS/ GPS signals. Post-sunset ionospheric plasma irregularities are a common characteristic of the equatorial ionosphere. These irregularities, associated with plasma bubbles, are defined as strong density depletions relative to the background plasma as determined by in situ measurements. 
Finding a system parameter's probability distribution function (PDF) can lead us to understand the system's underlying physics. In this study, we investigate the probability distribution of the integrated power of post-sunset plasma density irregularities in the equatorial ionosphere measured with the Langmuir probes on Swarm C in four different frequency bands between 0-1 Hz for the entire Swarm mission. We find evidence of  "heavy tail" distribution in the PDFs, indicating the system's complexity and self-organized criticality. Moreover, we study the relation between Integrated power and different geomagnetic indices, e.g. F10.7 and sunspot number, to find the potential drivers of severe events. While we find no obvious driver of individual events, we find a strong solar cycle dependence in their occurrence.

How to cite: Ghadjari, H., Knudsen, D., and Skone, S.: Probability distribution of integrated power of equatorial ionosphere plasma density fluctuations measured by the Swarm Langmuir probes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8677, https://doi.org/10.5194/egusphere-egu23-8677, 2023.

EGU23-10171 | Orals | ST3.3

Inferred Ionospheric irregularity scales from amplitude scintillation 

Karim Meziane, Abdelhaq M. Hamza, and Tayyil P. Jayachandran

The analysis of the structure function of a GNSS signal amplitude measured on the ground has revealed that ionospheric scintillation could be considered a proxy for ionospheric turbulence. More precisely, and in a recent report, the existence of a linear range with respect to the time lag in the structure function has been highlighted. In this context, the inertial-range analog has been determined from the analysis of a large set of scintillation events collected over several days from Pond Inlet located in the northern polar region and from Sao Paolo located at 23.2 degrees South of the Equator. At high latitude, we found that the mean value of the first-order scaling exponent is H = 0.55 ± 0.07, while a low altitude H is typically larger with H = 0.84 ±.11. This result clearly indicates that the long-time lag positive correlation remains persistent in the low latitude region. At high latitude however, both negative and positive long time lag correlation can occur. In addition, the obtained results clearly show that the inertial range analog is significantly smaller at high latitude, particularly the upper bound time lags at which the structure function deviates from linearity. This distinction may pinpoint to a difference in the ionospheric irregularity drift speed.   

How to cite: Meziane, K., Hamza, A. M., and Jayachandran, T. P.: Inferred Ionospheric irregularity scales from amplitude scintillation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10171, https://doi.org/10.5194/egusphere-egu23-10171, 2023.

EGU23-11628 | Orals | ST3.3

The regular solar wind impact on the high-latitude electron density in time scales of days and weeks 

Claudia Borries, Fredy Davies, Pelin Iochem, Samira Tasnim, and Joachim Vogt

Global changes in the state of the ionosphere-thermosphere system depend to a large extent on the energy input from the solar wind and magnetosphere, which occurs in the high-latitude regions. On the one hand energy is deposited in the form of Joule heating causing changes in the thermosphere composition and circulation. On the other hand, imposed electric fields change plasma transport. Joule heating is closely related to changes in the solar wind dynamic pressure, because it can cause a compression of the magnetosphere driving currents in the magnetosphere, and the currents transfer electromagnetic energy into the ionosphere. The enhancement of plasma convection in the polar ionosphere is related to the intensification of the convection electric field, which is driven by the solar wind sweeping across the open magnetic field lines of the polar magnetosphere. These changes are most significant during storm conditions, caused e.g. by coronal mass ejections and corotating interaction regions. The storm related energy release in the high-latitude ionosphere is impacting the thermosphere-ionosphere system on a global scale.

However, the solar wind impact causes a regular every day variability of the polar ionosphere, too. We are investigating how the solar wind variability in time scales of days and weeks is reflected in the ionosphere variability at Tromso, which is located in Scandinavia at 70°N, 19°E. We use cross correlation analysis of total electron content with solar wind merging electric field and dynamic pressure data. It can be shown that in timescales of days and weeks, the magnitude of correlation between TEC and solar wind reaches similar values to the correlation of TEC and F10.7. However, the results show that the correlation between TEC and solar wind parameters depends strongly on local time, season and solar cycle. There is a clear annual cycle in the variability of the correlation coefficient, with higher correlation values in winter than in summer. The positive correlation in winter close to local midnight hours is related to precipitation effects increasing the electron densities. During summer in solar maximum condition, clear negative correlation values are retrieved. These are considered to be caused by increased convection.

How to cite: Borries, C., Davies, F., Iochem, P., Tasnim, S., and Vogt, J.: The regular solar wind impact on the high-latitude electron density in time scales of days and weeks, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11628, https://doi.org/10.5194/egusphere-egu23-11628, 2023.

EGU23-12464 | ECS | Orals | ST3.3

Large Scale Temporal and Spatial Characteristics of E-region Plasma Irregularities Measured by SIMONe Norway 

Devin Huyghebaert, Jorge L. Chau, Andres Spicher, Magnus F. Ivarsen, Matthias Clahsen, Ralph Latteck, and Juha Vierinen

Recently it has been shown that the SIMONe meteor radar network located in northern Norway is capable of measuring ionospheric E-region coherent scatter with spatial and temporal resolutions on the order of 1.5 km and 2 s (Huyghebaert et al, 2022).  These measurements are further studied, where the coherent scatter measurements are used as a tracer for large scale ionospheric phenomena, such as plasma density enhancements and ionospheric electric fields.  By applying 2D Fourier analysis to range-time-intensity data, we perform a multi-scale spatial and temporal investigation to determine the change in range over time of the large scale ionospheric structures (> 1 km) which are compared with the line-of-sight velocities of the small scale structures (< 10 m) determined from the Doppler shift of the coherent scatter.  The spectral characteristics of the structures are also investigated. This aids in characterizing the source of the structures and provides crucial information about how energy is redistributed from large to small scales in the E-region ionosphere.  Four different events are examined from June and July of 2022.

Huyghebaert D, Clahsen M, Chau JL, Renkwitz T, Latteck R, Johnsen MG and Vierinen J (2022) Multiple E-Region Radar Propagation Modes Measured by the VHF SIMONe Norway System During Active Ionospheric Conditions. Front. Astron. Space Sci. 9:886037. doi: 10.3389/fspas.2022.886037

How to cite: Huyghebaert, D., Chau, J. L., Spicher, A., Ivarsen, M. F., Clahsen, M., Latteck, R., and Vierinen, J.: Large Scale Temporal and Spatial Characteristics of E-region Plasma Irregularities Measured by SIMONe Norway, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12464, https://doi.org/10.5194/egusphere-egu23-12464, 2023.

EGU23-14686 | Orals | ST3.3

Turbulence Properties of Kilometer-scale Equatorial Irregularities as Deduced from Swarm Satellites LP Observations 

Stephan C. Buchert, Sharon Aol, Luca Sorriso-Valvo, and Edward Jurua

The ESA Swarm satellites have since year 2014 provided measurements of electron density at a frequency of 2 Hz and at times also 16 Hz corresponding to about 500 m along the satellite paths. Spectral indices, structure functions and scaling exponents of these 16 Hz density estimates were analyzed to study the F-region ionospheric irregularities at altitudes between about 425 and 510 km. The data were obtained during the period from October 2014 to October 2022.The Power Spectral Densities (PSDs) observed followed to a very good approximation a power law. The values of spectral indices p obtained showed a peak centered at around -2.5, located at the Equatorial Ionization Anomaly (EIA) belts. The largest contribution to the spectra came from in the South American-Antlantic-African longitudes and it was generally low in the Asian-Pacific region. The angle between the Swarm satellite orbital path and the magnetic field (∠(B, v)) was examined. The highest percentage of occurrence of ionospheric irregularities and the peak in spectral index was obtained for ∠(B, v) between 0° and about 40°. Over this range of angles PSD spectra steepened with increasing ∠(B, v) (p becomes increasingly negative), consistent with local anisotropic turbulence at scales of a few km. The probability distributions of density differences (structure functions) are non-Gaussian at all orders, similar to many other observations in space plasma. The scaling exponent function is non-linearly concave, which is usually taken as a sign of intermittency.

How to cite: Buchert, S. C., Aol, S., Sorriso-Valvo, L., and Jurua, E.: Turbulence Properties of Kilometer-scale Equatorial Irregularities as Deduced from Swarm Satellites LP Observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14686, https://doi.org/10.5194/egusphere-egu23-14686, 2023.

EGU23-16036 | ECS | Posters on site | ST3.3

Exploring Characteristics of Turbulent Density Fluctuations in the Arctic Ionosphere with Multi-Point Measurements 

Theresa Rexer, Andres Spicher, Juha Vierinen, and Andreas Kvammen

Turbulence studies look at how energy is transferred between temporal and spatial scales (or wavenumber) by analyzing the power spectral density or structure function of a measured turbulent environment.
In the high-latitude ionosphere, the spatio-temporal characteristics of turbulent density fluctuations are not well understood. 
Currently, these are generally measured in-situ, using data from satellites or rockets that provide instantaneous measurements along the track.
However, to obtain a complete description of the fluctuating fields, time-series of volumetric measurements are needed.
In this work, we develop tools to characterize the statistical properties of ionospheric density fluctuations using multi-point measurements that are applicable to incoherent scatter radars such as the upcoming EISCAT_3D.
We utilize data from the AMISR radars in Resolute Bay, Canada, and compute the structure functions of ionospheric electron density fluctuations under various seasonal and geophysical conditions. We examine the nature of the fluctuations associated with multiple polar patches in more detail, shedding light on how energy is redistributed across the scales. 
With the upcoming EISCAT_3D radar, this project aims to investigate and resolve outstanding issues about the structuring of auroral dynamics and the physics involved in creating density irregularities. 

How to cite: Rexer, T., Spicher, A., Vierinen, J., and Kvammen, A.: Exploring Characteristics of Turbulent Density Fluctuations in the Arctic Ionosphere with Multi-Point Measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16036, https://doi.org/10.5194/egusphere-egu23-16036, 2023.

EGU23-16041 | ECS | Posters on site | ST3.3

Modeling of ionospheric irregularities in the Arctic region based on empirical orthogonal function method 

Yaqi Jin, Lasse Clausen, and Wojciech Miloch

The polar ionosphere is often highly structured with significant plasma irregularities, influencing the Global Navigation Satellite System (GNSS) service that relies on trans-ionospheric radio waves. Due to the practical usage, there is a high demand for modeling and forecasting of ionospheric irregularities. In this study, we develop a climatological model based on the long-term dataset (2010-2021) of rate of change of the total electron content (TEC) index (ROTI) maps from the International GNSS Service (IGS). The IGS ROTI maps are daily averaged in magnetic coordinates. In order to develop a climatological model, the ROTI maps are decomposed into a few base functions and coefficients using the empirical orthogonal function (EOF) method. The EOF method converges very quickly, and the first four EOFs could reflect the majority (96%) of the total data variability. Furthermore, the first four EOF base functions reflect different drivers of ionospheric irregularities. For example, the first EOF reflects the averaged ROTI activity and the impact of the solar radiation characterized by F10.7; the 2nd EOF base function reflects the impact of interplanetary magnetic field (IMF) Bz and electric field; the 3rd and 4th EOF base functions reflect the dawn-dusk asymmetry in the auroral oval and polar cap, and therefore related to the IMF By. To build an empirical model, we fit the EOF coefficients using geophysical proxies from four different categories (namely, solar radiation, magnetic indices, IMF, and solar wind coupling function) based on linear regression. The preliminary data-model comparison shows satisfactory results with a good correlation coefficient and adequate errors.

How to cite: Jin, Y., Clausen, L., and Miloch, W.: Modeling of ionospheric irregularities in the Arctic region based on empirical orthogonal function method, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16041, https://doi.org/10.5194/egusphere-egu23-16041, 2023.

EGU23-17309 | Posters virtual | ST3.3

ectron Aurora and polar rain dependencies on Solar Wind Drivers 

Simon Bouriat, Simon Wing, and Mathieu Barthélémy

Data analysis was performed using 17 years of DMSP SSJ/4/5 data to characterize the relations between the solar wind drivers and the electron low-energy fluxes measured on both magnetic poles (magnetic latitude above 55°). Inputs are solar wind velocity, density, dynamic pressure and Bz of the interplanetary magnetic field. Median of electron energy flux for each MLAT-MLT pair have been computed for given values of solar wind drivers. Results highlight that high velocity, density or pressure implies higher energy flux overall, higher polar rain energy fluxes, and wider nightside oval. There seems to be a positive correlation between polar rain and solar wind density as opposed to what Riehl & Hardy (1986) found. As a function of Bz, the oval width as a “U” shape and the polar cap activity a “V” shape, with their minimum at Bz around zero. 

Riehl, K. B., & Hardy, D. A. (1986). Average characteristics of the polar rain and their relationship to the solar wind and the interplanetary magnetic field. Journal of Geophysical Research: Space Physics, 91 (A2), 1557-1571. Retrieved from https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/JA091iA02p01557 doi: https://doi.org/10.1029/JA091iA02p01557

How to cite: Bouriat, S., Wing, S., and Barthélémy, M.: ectron Aurora and polar rain dependencies on Solar Wind Drivers, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17309, https://doi.org/10.5194/egusphere-egu23-17309, 2023.

EGU23-1590 | ECS | Posters virtual | ST3.4

3D reconstruction of CTIDs induced by hurricane Matthew on 7 October 2016 

Changzhi Zhai, Yutian Chen, and Shunrong Zhang

The temporal as well as vertical and horizontal variations of the concentric traveling ionospheric disturbances (CTIDs) caused by hurricane Matthew on 7 October 2016 were reconstructed using 3-dimensional computerized ionospheric tomography (3DCIT) technology, based upon the GNSS data from the dense receiver network over North America. The frequency range of disturbances was determined by spectrum analysis, and a Butterworth band-pass filter was used to de-trend the total electron content (TEC) sequences in order to determine TIDs. A remarkable CTID segment was detected at a distance of 1000 – 1500 km from the hurricane eye at ~5:40 – 6:10 UT on 7 October 2016, moving westward with the horizontal phase velocity of ~153.4 m/s, the period of ~30 min and the horizontal wavelength of ~276.1 km. The positive and negative wavefronts dominated the CITD at different times during the event. From 4:00 to 8:00 UT, the altitudinal variation of the CTIDs in electron density exhibited clear downward phase progression predominately in the range of 150 – 400 km altitudes, however, the percentage electron density disturbances were larger below 250 km. The inverted cone-like geometry of CTID wavefronts was presented. The vertical phase velocities of the CTIDs ~1100 km away from the hurricane eye in the northwest direction near 88°W, 34°N were ~203.7 – 277.8 m/s, and at the same location, the horizontal phase velocities at 300 km altitude were ~149.1 – 181.5 m/s, slightly larger than those at 200 km altitude (~145.1 – 178.5 m/s). 

How to cite: Zhai, C., Chen, Y., and Zhang, S.: 3D reconstruction of CTIDs induced by hurricane Matthew on 7 October 2016, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1590, https://doi.org/10.5194/egusphere-egu23-1590, 2023.

EGU23-2431 | Posters on site | ST3.4

Equatorial Electrojet and Counter Electrojet caused by the 15 January 2022 Tonga Volcanic Eruption 

Guan Le, Guiping Liu, Endawoke Yizengaw, and Christoph Englert

We present space and ground-based multi-instrument observations demonstrating the impact of the 2022 Tonga volcanic eruption on dayside equatorial electrodynamics. A strong counter electrojet (CEJ) was observed by Swarm and ground-based magnetometers on 15 January after the Tonga eruption and during the recovery phase of a moderate geomagnetic storm. Swarm also observed an enhanced equatorial electrojet (EEJ) preceding the CEJ in the previous orbit. The observed EEJ and CEJ exhibited complex spatiotemporal variations. We combine them with the Ionospheric Connection Explorer (ICON) neutral wind measurements to disentangle the potential mechanisms. Our analysis indicates that the geomagnetic storm had minimal impact; instead, a large-scale atmospheric disturbance propagating eastward from the Tonga eruption site was the most likely driver for the observed intensiYcation and directional reversal of the equatorial electrojet. The CEJ was associated with strong eastward zonal winds in the E-region ionosphere, as a direct response to the lower atmosphere forcing.

How to cite: Le, G., Liu, G., Yizengaw, E., and Englert, C.: Equatorial Electrojet and Counter Electrojet caused by the 15 January 2022 Tonga Volcanic Eruption, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2431, https://doi.org/10.5194/egusphere-egu23-2431, 2023.

EGU23-2511 | Posters on site | ST3.4

Why does the October effect not occur at night? 

Vivien Wendt, Helen Schneider, Daniela Banys, Marc Hansen, and Mark Clilverd

Radar waves with very low frequency (VLF) are reflected at the lower edge of the ionosphere, in the D-region. The D-region (60 - 90km) is influenced by the solar zenith angle and space weather from above as well as by dynamical and chemical processes in the mesosphere. During October there is a well-known sharp decrease of the daytime VLF amplitude between transmitter and receiver combinations whose great circle paths lie mainly in polar latitudes. Until now we do not know what causes the October effect. Space weather phenomena can be ruled out as a cause since their time scales are either too short or too long. The solar zenith angle, strongly influencing the seasonal variation of the VLF amplitude can also be ruled out as a similar behavior is not observed in spring. Thus, there is a strong assumption that neutral dynamical processes in the mesosphere play a major role. We assume and confirm that a regional warming in the lower mesosphere, occurring simultaneously and with similar characteristics as the October effect, plays a major role in the formation process of the October effect. The VLF reflection height is about 15km higher during nighttime than during daytime. This difference in combination with the location of the regional warming explains, why the October effect can not be observed during nighttime.

How to cite: Wendt, V., Schneider, H., Banys, D., Hansen, M., and Clilverd, M.: Why does the October effect not occur at night?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2511, https://doi.org/10.5194/egusphere-egu23-2511, 2023.

EGU23-2624 | ECS | Posters on site | ST3.4

The Impact of Sudden Stratospheric Warmings and Elevated Stratopause Events on the VLF signal in high latitudes 

Helen Schneider, Vivien Wendt, Daniela Banys, Marc Hansen, and Mark Clilverd

Sudden Stratospheric Warmings (SSW) and Elevated Stratopause (ES) events are atmospheric wave driven winter phenomena, which lead to significant changes in atmospheric dynamics and temperatures. SSWs are characterized by a sudden warming in the stratosphere by up to 90K and a mesospheric cooling by up to 30K. At the same time the background wind decelerates and can even revers which modifies the vertical mass transport. Occasionally SSW are followed by an ES where the stratopause at 50-60 km vanishes and subsequently reforms in elevated altitude ranges of 70-85 km. This leads to a temperature increase of up to 50 K in mesospheric heights. The temperature increase during an ES is accompanied by strongly enhanced positive zonal winds and a downward directed mass transport, which leads to changes in neutral chemistry.
Very low frequency (VLF) signals transmission, which is used for long distance communication, is generally conducted from a transmitter station to a receiver station within the so-called wave guide. This is the region between the Earth surface and the bottom side of the ionosphere (~60-90 km), which is behaving as a reflection boundary. Any changes in D-region ionization are able to modify the propagation of the VLF signal.
The above described significant changes in wind, temperature and neutral composition during SSW/ES events occur within the VLF reflection heights and likely influence the VLF propagation.

For the identification of SSW/ES induced perturbations of the VLF signal we need to remove the typical seasonal variation and outliers caused by noise, technical adjustments or solar events.  For this purpose, a quiet time curve is required, which represents the seasonal VLF signal variation under undisturbed conditions, for each link respectively. We developed the quiet time winter curve with a polynomial fit of the wintertime composite. In preparation for the composite, the VLF data needed to be leveled due to artificial amplitude steps with technical origin in the timeseries. The leveling was done with help of the Pruned Exact Linear Time method. Additionally, outliers have been removed using the Median Absolute Deviation, a method from robust statistics.

The developed quiet time winter curve allows us to determine VLF signal perturbations, which we analyze to examine the impact of SSW/ES events on the VLF signal. Furthermore, by studying different links in high latitudes, we want to investigate if there occur longitudinally differences in the VLF signal perturbation as the ES events vary strongly with longitude.

How to cite: Schneider, H., Wendt, V., Banys, D., Hansen, M., and Clilverd, M.: The Impact of Sudden Stratospheric Warmings and Elevated Stratopause Events on the VLF signal in high latitudes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2624, https://doi.org/10.5194/egusphere-egu23-2624, 2023.

EGU23-2886 | Orals | ST3.4 | Highlight

Atmosphere-ionosphere coupling following the Tonga eruption: global multi-scale ionospheric effects 

Shun-Rong Zhang, Ercha Aa, Juha Vierinen, Phil Erickson, Larisa Goncharenko, Anthea Coster, Wenbin Wang, and Liying Qian

The submarine volcanic eruption at Tonga on 15 January 2022 was a devastated geohazardous rated as VEI (Volcanic Explosivity Index) 5-6, which was the most powerful since the 1883 Krakatoa VEI 6 eruption. The release of enormous amounts of energy into the atmosphere triggered significant geophysical disturbances. In this presentation, we provide various upper atmospheric observations to demonstrate local, regional, and global ionospheric disturbances, including TID global propagation with the most intense, persistent, and consistent wave mode at 300-350 m/s phase speed , EIA deformation and x-cross pattern of EIA crest evolution, equatorial irregularities and bubbles, substantial plasma density depletion. Timing of these and many other observed ionospheric responses was consistent with the Lamb wave arrival, despite of other waves including acoustic and gravity waves as well as tsunami waves were also present in specific regions.  The eruption-excited atmospheric waves produced not only TID global propagation but also modulated the wind dynamos in both E and F regions, driving electrodynamic changes closely associated with EIA and EPBs phenomena at equatorial and low latitudes. These results suggested a new vertical coupling channel through which the intense atmospheric surface disturbance processes can produce far-reaching and long-lasting geospace impacts.

How to cite: Zhang, S.-R., Aa, E., Vierinen, J., Erickson, P., Goncharenko, L., Coster, A., Wang, W., and Qian, L.: Atmosphere-ionosphere coupling following the Tonga eruption: global multi-scale ionospheric effects, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2886, https://doi.org/10.5194/egusphere-egu23-2886, 2023.

EGU23-3289 | Orals | ST3.4

Atmospheric and ionospheric disturbances in Europe induced by Hunga eruption on 15 January 2022 

Jaroslav Chum, Tereza Šindelárová, Petra Koucká Knížová, Kateřina Podolská, Jan Rusz, Michael Danielides, and Carsten Schmidt

The massive explosive eruption of the Hunga Tonga volcano on 15 January generated atmospheric waves that were comparable with those generated by the Krakatoa 1883 eruption. The waves were recorded around the globe and affected also the ionosphere. We focus on observation of atmospheric waves in the troposphere and ionosphere in Europe. The tropospheric waves are studied using a large aperture array of microbarometers and the ionospheric disturbances are detected using continuous Doppler sounding. It is shown that long-period infrasound (periods longer than ~50 s) is observed simultaneously in the troposphere and ionosphere about an hour after the arrival of the first pressure pulse (Lamb wave) in the troposphere. Data analysis confirms propagation approximately along the shorter great circle path both for the infrasound and the Lamb wave. It is suggested that the infrasound propagated into the ionosphere probably due to imperfect refraction in the lower thermosphere. The observation of infrasound in the ionosphere at such large distances from the source (over 16 000 km) is rare and differs from ionospheric infrasound detected at large distances from the epicenters of strong earthquakes, because in the latter case the infrasound is generated locally by seismic waves. An unusually large traveling ionospheric disturbance (TID) observed in Europe and associated with the pressure wave from the Hunga Tonga eruption is also discussed. In addition, a probable observation of wave in the mesopause region approximately 25 min after the arrival of pressure pulse in the troposphere using a 23.4 kHz signal from a transmitter 557 km away is shown.

How to cite: Chum, J., Šindelárová, T., Koucká Knížová, P., Podolská, K., Rusz, J., Danielides, M., and Schmidt, C.: Atmospheric and ionospheric disturbances in Europe induced by Hunga eruption on 15 January 2022, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3289, https://doi.org/10.5194/egusphere-egu23-3289, 2023.

EGU23-3722 | ECS | Posters virtual | ST3.4

Diagnostic Analysis of the Physical Processes Underlying theLong-Duration O/N2 Depletion During the Recovery Phase ofthe 8 June 2019 Geomagnetic Storm 

Tingting Yu, Wenbin Wang, Zhipeng Ren, Xuguang Cai, Libo Liu, Maosheng He, Nicholas Pedatella, and Changzhi Zhai

A thermospheric O and N2 column density ratio (ΣO/N2) depletion with long-duration (>16 hr) was observed by the Global-scale Observations of the Limb and Disk at the Atlantic longitudes (75W–20W) and middle latitudes (20N–50N) during the recovery phase of the 8 June 2019 geomagnetic storm. The National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) simulations reproduced the ΣO/N2 depletion patterns with a similar magnitude, and indicated that the composition recovery at middle latitudes began several hours after the beginning of the recovery phase of the geomagnetic storm. The TIEGCM simulations enable quantitative analysis of the physical mechanisms driving the middle-latitude composition changes during the storm recovery phase. This analysis indicates that vertical advection and molecular diffusion dominated the initial recovery of composition perturbations at middle latitudes. Horizontal advection was also a main driver in the initial recovery of composition, but its contribution decreased rapidly. In the late recovery phase, the composition recovery was mainly determined by horizontal advection. In comparison, vertical advection and molecular diffusion played a much less important role.

How to cite: Yu, T., Wang, W., Ren, Z., Cai, X., Liu, L., He, M., Pedatella, N., and Zhai, C.: Diagnostic Analysis of the Physical Processes Underlying theLong-Duration O/N2 Depletion During the Recovery Phase ofthe 8 June 2019 Geomagnetic Storm, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3722, https://doi.org/10.5194/egusphere-egu23-3722, 2023.

EGU23-4278 | ECS | Orals | ST3.4

Improved field-aligned current and radial current estimates at low and middle latitudes deduced by the Swarm dual-spacecraft 

Fengjue Wang, Hermann Luehr, Chao Xiong, Jaeheung Park, and Yunliang Zhou

The Swarm satellite constellation provides an excellent opportunity to explore ionospheric current systems. In this study we performed a detailed analysis of the ionospheric radial current (IRC) and inter-hemispheric field-aligned current (IHFAC) estimates at equatorial and low latitudes derived from the single-satellite and dual-spacecraft (dual-SC) approaches. We found that the diurnal variations of average IHFACs from both approaches agree qualitatively with each other for all seasons. But the amplitudes of single-satellite results reach only about 70% of those from the dual-SC. This difference is attributed to the fact that only the magnetic field By component is utilized in the single-satellite approach, while both Bx and By components are considered in the dual-SC approach. Above the magnetic equator, the IRCs derived from single-satellite approach show spurious tidal signatures, caused by equatorial electrojet (EEJ) contributions to the dBy component. The EEJ does not contaminate dual-satellite results. Further, we improved the IHFACs from the dual-satellite approach by considering the local influence of the ambient magnetic field on current densities and normalize them to their ionospheric E-region footprints. Then we extend the analysis to ±60° MLat; the middle latitude IHFACs show features different from those at low latitudes. They are dominated by longitudinal wave-1 and wave-2 patterns. A superposition of these tidal components reflects confinement of the IHFAC modulation to daytime and the western hemisphere. The tidal signatures at middle latitudes are better organized in universal time than in local time. The strongest IHFACs appear at 18-19 UT, near noon in the American sector. This is related to the overlap with the South Atlantic Anomaly.

How to cite: Wang, F., Luehr, H., Xiong, C., Park, J., and Zhou, Y.: Improved field-aligned current and radial current estimates at low and middle latitudes deduced by the Swarm dual-spacecraft, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4278, https://doi.org/10.5194/egusphere-egu23-4278, 2023.

EGU23-4285 | ECS | Posters virtual | ST3.4

Dayside neutral wind vertical shear at low F region altitude observed by the ICON satellite 

yuyang Huang and Chao Xiong

The Michelson Interferometer for Global High-Resolution Thermospheric Imaging (MIGHTI) onboard the Ionospheric Connection Explorer (ICON) mission measures the neutral winds from 88 km to 310 km altitudes, which provides a good opportunity to investigate the vertical distribution of neutral winds, especially their vertical shears. Based on over two years data from MIGHTI/ICON, we focused on the wind vertical shears at the low F region (from 88 km to 245 km) in this study. As the green line of MIGHTI works only on the dayside, only the dayside from 0600 to 1800 local time (LT) has been considered. As a result, there were 206 and 96 orbits were identified with clear vertical shears for the meridian and zonal wind components, respectively. Interestingly, such wind vertical shears occurred not only during magnetically disturbed periods, as there were 75.73% and 78.12% orbits with vertical shears identified in the meridional and zonal wind with Kp less than 2. Dependences of the wind vertical shears on local time (LT), geographic latitude (Glat) and longitude (Glon) have been further checked, and we found that the wind vertical shears have different trends for the LT dependence, e.g., the mean altitude of meridional (zonal) wind reversed from southward to northward (westward to eastward)  is higher at dawn, and then slowly decreases toward dusk; or the mean altitude of wind reversal is higher at dusk and slowly increases towards dusk. Such two kinds of altitude trends of the wind vertical shears were also found for the dependence on Glat, but not on Glon. The mean altitudes of wind reversal are around 160 km for most of the Glon sectors, with only a slight decrease or increase at the sector where the magnetic equator is far away from the geographic equator, indicating that the ion drag should also play a role in causing the wind vertical shears. The relation between the wind vertical shears at E (England et al., 2022) and low F region altitudes have been further investigated. From the orbits with wind vertical shears at low F region identified, there were about 90% orbits with also wind vertical shears simultaneously observed at the E region, but the altitude trends can be the same or opposite for the vertical shears at the two regions, even for the same orbit. Such a relation suggests that the causes for wind vertical shears at the E and low F region altitudes could be different.

How to cite: Huang, Y. and Xiong, C.: Dayside neutral wind vertical shear at low F region altitude observed by the ICON satellite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4285, https://doi.org/10.5194/egusphere-egu23-4285, 2023.

EGU23-4606 | Orals | ST3.4

Coordinated Observations of Migrating Tides by Multiple Meteor Radars in the Equatorial Mesosphere and Lower Thermosphere 

Wen Yi, Jianyuan Wang, Xianghui Xue, Robert Vincent, Paulo Batista, Toshitaka Tsuda, and Nicholas Mitchell

We present the migrating tidal winds decomposed jointly from multiple meteor radars in four longitudinal sectors situated in the equatorial mesosphere and lower thermosphere. The radars are located in Cariri, Brazil (7.4°S, 36.5°W), Kototabang, Indonesia (0.2°S, 100.3°E), Ascension Island, United Kingdom (7.9° S, 14.4°W), and Darwin, Australia (12.3°S, 130.8°E). Harmonic analysis was used to obtain amplitudes and phases for diurnal and semidiurnal solar migrating tides between 82 and 98 km altitude during the period 2005–2008. To verify the reliability of the tidal components calculated by the four meteor radar wind measurements, we also present a similar analysis for the Whole Atmosphere Community Climate Model winds, which suggests that the migrating tides are well observed by the four different radars. The tides include the important tidal components of diurnal westward-propagating zonal wavenumber 1 and semidiurnal westward-propagating zonal wavenumber 2. In addition, the results based on observations were compared with the Climatological Tidal Model of the Thermosphere (CTMT). In general, in terms of climatic features, our results for the major components of migrating tides are qualitatively consistent with the CTMT models derived from satellite data. In addition, the tidal amplitudes are unusually stronger in January–February 2006. This result is probably because tides were enhanced by the 2006 Northern Hemisphere stratospheric sudden warming event.

How to cite: Yi, W., Wang, J., Xue, X., Vincent, R., Batista, P., Tsuda, T., and Mitchell, N.: Coordinated Observations of Migrating Tides by Multiple Meteor Radars in the Equatorial Mesosphere and Lower Thermosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4606, https://doi.org/10.5194/egusphere-egu23-4606, 2023.

EGU23-4633 | Posters virtual | ST3.4

Responses of the middle and upper atmospheric wind to geomagnetic activities 

Guoying Jiang, Jinfang Liu, Jiyao Xu, and Yajun Zhu

Responses of the middle and upper atmospheric (80-100 km ) wind to geomagnetic activities have been investigated using neutral wind data from 2012 to 2018 years, which were observed by Mohe, Beijing and Wuhan Meteor radars. Daily averaged wind data for geomagnetic quiet condition (Kp<=2 ) and geomagnetic disturb condition (Kp>=4) were chosen for comparison, and the variation characteristics of wind during geomagnetic disturbances were obtained. The observations show that the influence of geomagnetic activity on zonal wind varied with seasons and latitudes. For zonal wind, the effect of geomagnetic activity at higher latitudes tended to be more westerly wind in the upper mesosphere and more easterly wind in the lower thermosphere, and the differences between disturbed and quiet conditions were on the order of 3 m/s; while for the lower latitudes, it tended to be more easterly wind in the 80-100 km region, and the influence were about 5 m/s. In spring, the three stations had similar tendencies, and had no latitude differences. But the easterly wind in the middle atmosphere became stronger with the decrease of latitude in summer/winter. The effect of geomagnetic activities on the meridional wind had seasonal differences. The influence of geomagnetic activities in spring and winter was stronger than that in summer and autumn. In winter, the effect of geomagnetic activity on the meridional wind in middle and low latitudes was stronger than that in higher latitudes. According to the calculation results, the influence on zonal wind was about 5 m/s to 10 m/s, and on meridional wind was about 3 m/s to 5 m/s. The impact of geomagnetic activities on MLT wind can penetrate down to about 80 km. At this height, the influence on zonal wind was the strongest in spring, reaching 8 m/s, and on meridional wind was the strongest in spring/winter, reaching 5 m/s.

How to cite: Jiang, G., Liu, J., Xu, J., and Zhu, Y.: Responses of the middle and upper atmospheric wind to geomagnetic activities, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4633, https://doi.org/10.5194/egusphere-egu23-4633, 2023.

We report a world record of lidar profiling of metallic Ca+ ions up to 300 km in the midlatitude nighttime ionosphere during geomagnetic quiet time. Ca+ measurements (∼80–300 km) were made over Beijing (40.42°N, 116.02°E) with an Optical-Parametric-Oscillator-based lidar from March 2020 through June 2021. Main Ca+ layers (80–100 km) persist through all nights, and high-density sporadic Ca+ layers (∼100–120 km) frequently occur in summer. Thermosphere-ionosphere Ca+ (TICa+) layers (∼110–300 km) are likely formed via Ca+ uplifting from these sporadic layers. The lidar observations capture the complete evolution of TICa+ layers from onset to ending, revealing intriguing features. Concurrent ionosonde measurements show strong sporadic E layers developed before TICa+ and spread F onset. Neutral winds can partially account for observed vertical transport but enhanced electric fields are required to explain the results. Such lidar observations promise new insights into E- and F-region coupling and plasma inhomogeneities.

How to cite: Jiao, J.: Meteoric Ca Ion Transport From ∼80 to 300 km in the Midlatitude Nighttime Ionosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4640, https://doi.org/10.5194/egusphere-egu23-4640, 2023.

EGU23-5770 | Orals | ST3.4

Low Latitude Ionosphere Observed by the Sanya Incoherent Scatter Radar 

Xinan Yue, Weixing Wan, Baiqi Ning, Feng Ding, Junyi Wang, Yihui Cai, Ning Zhang, Mingyuan Li, Yonghui Wang, Xu Zhou, and Zhongqiu Wang

Sanya (18.3°N, 109.6°E) Incoherent Scatter Radar (SYISR) is a newly built ISR in low latitude China. The unique features of SYISR include a single-channel directly connected T/R unit and antenna, a radar array monitoring and calibration network, environmental adaptability design and open architecture. Since 2022, we have run SYISR almost continuously. In this presentation, at first we will generally describe the technical details of SYISR. Then we will show the ionospheric observations made by SYISR, including equatorial bubble, ion line and plasma line results, and derivation of low latitude neutral wind and ionospheric electric field. At the end, we will introduce the development status of the SYISR Tristatic System.

How to cite: Yue, X., Wan, W., Ning, B., Ding, F., Wang, J., Cai, Y., Zhang, N., Li, M., Wang, Y., Zhou, X., and Wang, Z.: Low Latitude Ionosphere Observed by the Sanya Incoherent Scatter Radar, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5770, https://doi.org/10.5194/egusphere-egu23-5770, 2023.

Global-scale waves, such as tides and traveling planetary waves, are an important part of the meteorology of the mesosphere and lower thermosphere (MLT) region. The amplitude and phase of these waves can be determined by analyzing longitude-time data given at a certain height and latitude. The standard technique is the least-squares Fourier method. However, it has difficulties in resolving the temporal variability of the wave activity. Tides and traveling planetary waves are known to show considerable temporal variability in the MLT region. In this presentation, a simple method to derive Fourier-wavelet spectra, which can resolve temporal variability of wave activity, is introduced. The technique enables to obtain a 'wavelet-like' spectrum, separately for eastward- and westward-propagating global-scale waves with different zonal wavenumbers. Application examples are presented using data from whole atmsophere models. The results suggest that the technique is capable of capturing bursts of global-scale wave activity in the MLT region during sudden stratospheric warming events.

How to cite: Yamazaki, Y.: A simple method to derive Fourier-wavelet spectra for studying global-scale waves in the mesosphere and lower thermosphere region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6030, https://doi.org/10.5194/egusphere-egu23-6030, 2023.

EGU23-6372 | ECS | Orals | ST3.4

Numerical simulations of metallic ion density perturbations in sporadic E layers caused by gravity waves 

Lihui Qiu, Yosuke Yamazaki, Tao Yu, Erich Becker, Yasunobu Miyoshi, Yifan Qi, Tarique A Siddiqui, Claudia Stolle, Wuhu Feng, Jin Wang, and Yu Liang

The ionospheric sporadic E (Es) layer is a thin and dense metallic ion layer that occasionally appears at altitudes between 95 and 125 km. The layer-forming process is controlled by the vertical wind shear that is closely linked to the atmospheric tides forced by solar radiation. The diurnal, semidiurnal, terdiurnal and quarterdiurnal variations in the Es layer occurrence rate have been revealed by observations. However, how the gravity wave affects the Es layer has not been well revealed. Using the 1-D Es layer model driven by neutral winds from the HIAMCM model (High Altitude Mechanistic general Circulation Model), this work simulated the physical process of the Es layer evolution modulated by gravity waves. The results show the short-period metallic ion density disturbance (1.5-3h) caused by gravity waves. The sporadic E layer can be destroyed or enhanced by gravity waves.

How to cite: Qiu, L., Yamazaki, Y., Yu, T., Becker, E., Miyoshi, Y., Qi, Y., Siddiqui, T. A., Stolle, C., Feng, W., Wang, J., and Liang, Y.: Numerical simulations of metallic ion density perturbations in sporadic E layers caused by gravity waves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6372, https://doi.org/10.5194/egusphere-egu23-6372, 2023.

EGU23-6455 | Posters on site | ST3.4

Planetary-scale MLT waves diagnosed through multi-station methods 

Maosheng He

Most experimental investigations on planetary-scale waves in the mesosphere lower thermosphere (MLT) region are based on single-station or -satellite spectral analysis methods, which are subject to intrinsic spectral aliasing/ambiguity. To conquer the aliasing, the author developed and implemented dual- and multi-station spectral methods in a series of recent works. These methods were implemented on meteor radar observations and surface magnetometer observations. A variety of waves were discovered or investigated in terms of seasonal variations and responses to sudden stratospheric warming events, including lunar and solar tides (migrating and non-migrating), Rossby wave normal modes, quasi-two-day waves, ultra-fast Kelvin waves, and secondary waves of wave-wave nonlinear interactions between the previous waves. The current paper uses synthetic data to illustrate the three methods and reviews comparatively these methods and results in plain language.

How to cite: He, M.: Planetary-scale MLT waves diagnosed through multi-station methods, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6455, https://doi.org/10.5194/egusphere-egu23-6455, 2023.

EGU23-8276 | Orals | ST3.4

Observations and modelling of fast vertical sub-auroral plasma uplift during geomagnetic storms 

Dimitry Pokhotelov, Florian Günzkofer, Larisa Goncharenko, and Philip J. Erickson

During geomagnetic storms, ionospheric plasma is transported across high latitudes by the enhanced solar wind – magnetosphere coupling. The anti-sunward plasma convection results in polar cap plasma anomalies, such as the tongue of ionisation (TOI). Fast plasma uplifts at sub-auroral latitudes, due to the vertical coupling via electric fields and/or thermospheric neutral winds, are generally responsible for these long-lasting TOI anomalies. Particularly in the North American sector, TOI anomalies, as well as associated electric drifts, have been detected in observations using global positioning system signals (total electron content), in-situ satellite measurements, and altitude-resolved profiles from ground-based incoherent scatter radars. Recent modelling developments have enabled simulations of the TOI anomalies, even under extreme geomagnetic storm conditions. In this study, rare direct observations of plasma uplifts by the Millstone Hill incoherent scatter radar (288.5°E, 42.6°N) during the geomagnetic storm of November 2004 are analysed and compared to first-principles numerical simulations. These indicate that enhanced convection electric fields are the primary source of plasma uplifts, at least during the storm's main phase, and that the choice of plasma convection model is crucial for accurate modelling results.

 

How to cite: Pokhotelov, D., Günzkofer, F., Goncharenko, L., and Erickson, P. J.: Observations and modelling of fast vertical sub-auroral plasma uplift during geomagnetic storms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8276, https://doi.org/10.5194/egusphere-egu23-8276, 2023.

EGU23-8368 | ECS | Orals | ST3.4

Short-term Variability of the Non-migrating Tide DE3 (from SABER, TIDI, and MIGHTI) and its Impact on the Ionosphere 

Manbharat Dhadly, McArthur Jones, and Douglas Drob

This investigation is focused on resolving daily diurnal eastward propagating tide with zonal number 3 (DE3) (3,3) Hough mode variations and their potential impact on the ionosphere, using TIMED/TIDI and SABER, ICON/MIGHTI, COSMIC-2 Global Ionospheric Specification (GIS), and TIME-GCM. A Hough mode fitting approach was used to estimate (3,3) amplitudes and phases from observations, while Fourier decomposition was utilized for TIME-GCM and COSMIC-2/GIS to validate and probe potential ionospheric impacts. In 2020-2021, TIDI, SABER, and MIGHTI (3,3) daily tidal estimates were in good agreement, with correlation coefficients ranging from 0.73-0.83. In 2010, mean daily (3,3) amplitude variability in TIDI and SABER reached ~5 m/s and ~2 K, respectively, but could increase by a factor of 2 or more over a week. Furthermore, strong increases in DE3 from days to weeks correspond with similar increases in F-region ionospheric wave-4 amplitudes from both models and observations which signify the lower atmospheric meteorology impact on the ionosphere.

How to cite: Dhadly, M., Jones, M., and Drob, D.: Short-term Variability of the Non-migrating Tide DE3 (from SABER, TIDI, and MIGHTI) and its Impact on the Ionosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8368, https://doi.org/10.5194/egusphere-egu23-8368, 2023.

High-rate radio occultation (RO) in COSMIC2 (FORMOSAT7) enables us to investigate the continuous variability of the ionosphere at a Spatio-temporal resolution which was unthinkable a few decades ago. We present unique characteristics of ionospheric wavenumber structures observed using COSMIC2 RO data, not reported before. Altitude-longitude maps of normalized electron density of local time ionosphere in the Equatorial Ionization Anomaly (EIA) region, indicate wavenumber structures with vertically tilted phase fronts. The longitudinal extent of a tilted wavenumber 4 (WN4) phase front approximates its zonal wavelength in the local-time ionosphere, i.e., ~900 in longitudes. WN4 filtered component indicates a more significant tilt (when visible), with a larger longitudinal extent of a wavenumber structure in the vertical plane. High latitudinal resolution investigation of wavenumber structure presents a significant difference in the characteristics of wavenumber structures at different geomagnetic latitudes within the EIA region. During the daytime WN4 structure in the EIA crest region is out of phase with respect to that in the EIA trough region. However, the two were observed to be in phase with each other during the nighttime. These characteristics also vary with altitude. Above 400 km WN4 structure in the EIA crest and trough region is seen to be in phase with each other at all local times. CREST. These results highlight that, while the direct role of non-migrating tides, which provides the vertical tilt to the wavenumber structure, maybe the dominant mechanism, however, electrodynamical transport of plasma in the EIA region driven by eastward zonal electric field during the daytime also plays a significant role in the formation of wavenumber structure. During the nighttime, in the absence of the fountain effect, wavenumber structures are driven by the direct forcing of non-migrating tides within the EIA region. The results will be presented and discussed in light of existing knowledge of the formation of wavenumber structures and the impact of non-migrating tides on the local-time ionosphere.

How to cite: Joshi, L. M.: Characteristics of ionospheric wavenumber structures in COSMIC-2 RO observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8943, https://doi.org/10.5194/egusphere-egu23-8943, 2023.

EGU23-9189 | ECS | Orals | ST3.4

Combined measurements with the EISCAT radar and the Nordic Meteor Radar Cluster to determine AGW-TID wave parameters 

Florian Günzkofer, Dimitry Pokhotelov, Gunter Stober, Ingrid Mann, Sharon L. Vadas, Erich Becker, Anders Tjulin, Njål Gulbrandsen, Johan Kero, Alexander Kozlovsky, Mark Lester, Nicholas Mitchell, Satonori Nozawa, Masaki Tsutsumi, and Claudia Borries

Atmospheric Gravity Waves (AGWs) forced in the lower atmosphere are known to have a significant impact on the mesosphere and lower thermosphere (MLT) region. In the ionosphere, they can generate Medium-Scale Traveling Ionospheric Disturbances (MSTIDs). These disturbances roughly occur on time scales of 15−80 min and are therefore often parametrized rather than directly resolved in ionosphere models. The energy and momentum transport by AGW-TIDs strongly depends on their wave parameters. Measurements of AGW-TIDs in the MLT region and determination of the wave parameters (vertical and horizontal wavelength, wave period and propagation direction) are therefore an essential step to improve ionosphere modelling. However, measurements that provide a good resolution in the vertical dimension (≲ 10 km) and time (≲ 10 min) as well as a large enough coverage in the horizontal dimension (≳ 300 × 300 km) are difficult at MLT altitudes. We show, that combined measurements of the EISCAT VHF incoherent scatter radar and the Nordic Meteor Radar Cluster allow to determine the wave parameters of AGW-TIDs across the whole MLT region. Fourier filter methods are used to separate wave modes by wavelength, period and propagation direction. The extracted wave modes are fitted with wave functions in time-altitude and horizontal cross sections which gives the wave parameters. The coverage regions of the two applied instruments are separated only by approximately 10 km in altitude, which allows to identify a single wave mode in both measurements. We present the developed techniques on the example of a strongly pronounced AGW-TID measured on July 7, 2020. As a first application, two measurement campaigns have been conducted in early September and mid-October 2022 to study possible changes in AGW-TID parameters due to the MLT fall transition occurring around equinox. Another possible application of our method is to infer thermospheric neutral winds from the observed waves. We demonstrate this process under the assumption of the anelastic dissipative gravity wave dispersion relation.

How to cite: Günzkofer, F., Pokhotelov, D., Stober, G., Mann, I., Vadas, S. L., Becker, E., Tjulin, A., Gulbrandsen, N., Kero, J., Kozlovsky, A., Lester, M., Mitchell, N., Nozawa, S., Tsutsumi, M., and Borries, C.: Combined measurements with the EISCAT radar and the Nordic Meteor Radar Cluster to determine AGW-TID wave parameters, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9189, https://doi.org/10.5194/egusphere-egu23-9189, 2023.

EGU23-10168 | Orals | ST3.4

The Atmospheric Waves Experiment 

Pierre-Dominique Pautet, Michael John Taylor, Yucheng Zhao, Jeffrey Forbes, David Fritts, Stephen Eckermann, Han-Li Liu, Jonathan Snively, Diego Janches, Burt Lamborn, Harri Latvakovski, and Erik Syrstad

The Atmospheric Waves Experiment (AWE) is a new NASA mission aimed at investigating the effects of tropospheric weather on space weather. An Advanced Mesospheric Temperature Mapper (AMTM) airglow imager will be deployed on the International Space Station (ISS) in December 2023. This proven instrument will map the nighttime mesospheric temperature at the altitude of the hydroxyl (OH) layer (~87 km) during two years, providing 2D gravity wave (GW) fields over a 600 km field-of-view, every second.

Four state-of-the-art models will also help achieving the three science objectives:

  • Quantify the seasonal and regional variabilities and influences of GWs near the mesopause,
  • Identify the dominant dynamical processes controlling GWs observed near the mesopause,
  • Estimate the wider role of GWs in the Ionosphere-Thermosphere-Mesosphere (ITM).

This presentation will give an overview of the AWE mission and describe the future data levels using synthetic images.

How to cite: Pautet, P.-D., Taylor, M. J., Zhao, Y., Forbes, J., Fritts, D., Eckermann, S., Liu, H.-L., Snively, J., Janches, D., Lamborn, B., Latvakovski, H., and Syrstad, E.: The Atmospheric Waves Experiment, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10168, https://doi.org/10.5194/egusphere-egu23-10168, 2023.

EGU23-10426 | Orals | ST3.4

Statistical study on plasma velocities in bottom-side ionosphere over low latitude Hainan station: Digisonde measurement 

Guojun Wang, Jiankui Shi, Zheng Wang, Zhengwei Cheng, Xiao Wang, and Sheping Shang

In this paper, the data measured with Digisonde at the low-latitude Hainan station from 2003 to 2016 are statistically analyzed to specify the diurnal average variations of the bottom-side F region ionospheric plasma velocity vector V. This is the first comprehensive analysis of Digisonde measurements of low latitude F region plasma velocities in the East Asian sector that use a database covering more than one solar cycle. The vector components VN, VE, and VZ are analyzed for two levels of solar flux and two levels of geomagnetic activity, respectively. The diurnal variations of the average VZ show three positive peaks near the prereversal enhancement (PRE) period, pre-midnight, and before sunrise, respectively, and a prominent valley in the early morning. The averaged VZ significantly increased with solar flux in the period of PRE during equinoxes, but it was only slightly affected by Kp. The VE component was westward in daytime and eastward in nighttime. The average eastward VE increased significantly with solar flux but decreased with Kp, whereas the average westward VE exhibited only a small variation with solar flux and Kp. The average VN was almost southward independent of solar flux and Kp. The plasma velocities over the Hainan station were mainly caused by the electric field and neutral wind. Our results show that the features of the vertical and meridional velocities over the Hainan station in the morning associated with the formation of the equatorial ionization anomaly (EIA).

How to cite: Wang, G., Shi, J., Wang, Z., Cheng, Z., Wang, X., and Shang, S.: Statistical study on plasma velocities in bottom-side ionosphere over low latitude Hainan station: Digisonde measurement, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10426, https://doi.org/10.5194/egusphere-egu23-10426, 2023.

EGU23-10463 | ECS | Orals | ST3.4

Longitudinal Structures of Zonal Wind in the Thermosphere by the ICON/MIGHTI and the Main Wave Sources 

Dan Li, Hong Gao, Jiyao Xu, Yajun Zhu, Qiuyu Xu, Yangkun Liu, and Hongshan Liu

In this study, the neutral wind observations from the Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) instrument onboard Ionospheric CONnections (ICON) are used to investigate the longitudinal structure of zonal wind between 100 and 300 km during daytime. The four-peaked structure is prominent in June and August, and transforms to the three-peaked structure with altitude in October. The longitudinal wavenumber 1-4 patterns (WN1-WN4) are extracted, then the altitude-month distributions of WN1-WN4 and their contributions to the longitudinal structure are compared. The amplitudes of WN3 and WN4 show seasonal dependence, and the amplitude of WN4 exhibits obvious vertical propagation from the mesosphere and lower thermosphere (MLT) to the upper thermosphere in summer and autumn. WN1 is an important contributor to the longitudinal structure, WN4 is the primary contributor in the lower altitude ranges in summer and autumn at three latitudes. The contributions of WN3 (WN1) increase holistically with latitude in summer (spring, autumn, and winter). And the main wave sources of WN1-WN4 are matched further in different seasons in the 100-106 km and 210-300 km altitude regions. The main wave sources of WN1 and WN2 have complex variations with altitude, latitude, and season, while WN3 (WN4) is clearly influenced by DE2 (DE3 and SE2).

How to cite: Li, D., Gao, H., Xu, J., Zhu, Y., Xu, Q., Liu, Y., and Liu, H.: Longitudinal Structures of Zonal Wind in the Thermosphere by the ICON/MIGHTI and the Main Wave Sources, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10463, https://doi.org/10.5194/egusphere-egu23-10463, 2023.

The seasonal and interannual variations of global tides of neutral winds in the mesosphere and lower thermosphere (MLT) are investigated based on the neutral horizontal wind data measured by TIMED Doppler interferometer (TIDI). The particular focus is on how the seasonal variation of tidal amplitude varies in response to solar cycle (SC) and to the quasi-biennial oscillation in winds in the lower stratosphere (SQBO). We find that the responses of seasonal variations of tides to SQBO and SC are comparable in magnitude to those of their corresponding annual means. Further, we show that the response patterns of seasonal variations of tides to SQBO and SC are not always similar to those of their corresponding annual means, which indicates that the tidal responses differ at different times of the year. In addition, we reveal that migrating tides show strong terannual oscillations (TAO) especially in meridional wind, whereas nonmigrating tides do not show obvious TAO.

How to cite: Liu, Y., Xu, J., Smith, A., and Liu, X.: Seasonal and Interannual Variations of Global Tides of Neutral Winds in the Mesosphere and Lower Thermosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10550, https://doi.org/10.5194/egusphere-egu23-10550, 2023.

EGU23-10573 | Posters virtual | ST3.4

Automatic Spread F Detection and classification at Hainan Station of Chinese Meridian Project 

Zheng Wang, Pengdong Gao, Guojun Wang, and Jiankui Shi

The spread F phenomenon (SF), i.e., the spread characteristics on F trace in ionogram, is considered to be caused by ionospheric disturbances. The SF image features are considered to be corresponding to different physical mechanism. According to the URSI handbook of ionogram interpretation and reduction, depending on the shape of diffusion on ionogram, the SF all over the world could be divided into 4 types: FSF/RSF/MSF/BSF. However, we have found at low latitude, BSF is rare and strong RSF (SSF) is a major type. For the ionogram data obtained from Hainan Station (19.5°N, 109.1°E, magnetic 11°N), the Deep Learning technique is used for the image characteristics, making a model for automatic SF detection and classification at this station. No matter what the ionogram data formats or the ionosonde models, the model could automatic classify the SF as FSF/RSF/MSF/SSF for the first time.

How to cite: Wang, Z., Gao, P., Wang, G., and Shi, J.: Automatic Spread F Detection and classification at Hainan Station of Chinese Meridian Project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10573, https://doi.org/10.5194/egusphere-egu23-10573, 2023.

EGU23-11009 | Orals | ST3.4

Interannual Variability of Tidal Dynamics in the Tropical MLT 

Valery Yudin, Larisa Goncharenko, Svetlana Karol, Ruth Lieberman, Joe McInerney, Nicholas Pedatella, and Valery Yudin

The impact of the stratospheric Quasi-Biennial Oscillations (QBO) and Semi-Annual Oscillations (SAO) and physics of gravity waves (GW) on the dynamics and transport in the Mesosphere and Lower Thermosphere (MLT) has been examined in simulations of two Whole Atmosphere Models (WAM and WACCM-X) during the last decade. In the low-latitude MLT the year-to-year variations of the diurnal tide amplitudes and mean flow of whole atmosphere simulations constrained below 40 km by reanalysis data are in the good agreement with the observed interannual variability. The Mar-Apr diurnal tide amplitudes simulated by models display the observed enhancements (~50-100%) of amplitudes during the westerly QBO years. The observed influence of QBO and SAO on the tidal dynamics in the MLT is well captured by simulations that are capable to reproduce the global and regional tidal variability deduced from the space-borne and ground-based measurements of temperature and winds. Comparisons between simulations and observations, along with the model sensitivity studies highlight needs to quantify and constrain impact of mesoscale GW dynamics and physics in whole atmosphere predictions.

How to cite: Yudin, V., Goncharenko, L., Karol, S., Lieberman, R., McInerney, J., Pedatella, N., and Yudin, V.: Interannual Variability of Tidal Dynamics in the Tropical MLT, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11009, https://doi.org/10.5194/egusphere-egu23-11009, 2023.

EGU23-11357 | ECS | Posters virtual | ST3.4

Lidar Observations of Thermosphere-Ionosphere Na (TINa) Layers at two nearby stations in North China 

Fang Wu, Guotao Yang, and Jing Jiao

The metal layers in the Earth’s upper atmosphere have received growing attention in recent years because of the discovery of the Thermosphere-Ionosphere metal (TIMt) Layers by lidar. In the reports of lidar detection TIMt Layers, the highest metal atom layer is Thermosphere-Ionosphere Na (TINa) Layers observed at Yanqing station (40.42°N, 116.02°E, Xun et al., 2019), while the Ca+ Ions Transport From ∼80 to 300 km were also observed at Yanqing station (Jiao et al., 2022). According to their morphological characteristics and occurrence frequency, and referring to the previous reports, the TINa layers observed at mid-latitude can be mainly classified into the following four types: lower thermosphere sporadic Na layers, dawn thermosphere-ionosphere Na layers, midnight thermosphere-ionosphere Na layers and mid-latitude thermosphere-ionosphere Na layers (Mid-TINa). Moreover, there are rare reports of the small scale horizontal distributions of TiNa layers. In 2014, another Na lidar was developed at Pingquan station(41.0°N, 118.7°E), which is about 250 km away from Yanqing station. By analysis data of these two lidar, the occurrence frequency, distribution, and morphological characteristics of four types TINa layers are studied.

How to cite: Wu, F., Yang, G., and Jiao, J.: Lidar Observations of Thermosphere-Ionosphere Na (TINa) Layers at two nearby stations in North China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11357, https://doi.org/10.5194/egusphere-egu23-11357, 2023.

Ionospheric perturbations during the Sudden Stratosphere Warming (SSW) events reflect the lower atmosphere-ionosphere coupling and thus become a research hot-spot. Nevertheless, most previous related studies focused on the low latitude. Comparatively, ionospheric perturbations in the middle and high latitudes during the Arctic SSW events are relatively less studied. The current work analyzed the ionosphere perturbations in the American southern middle latitude during the Arctic SSW with total electron content and NmF2. Unexpected strong connection between the major Arctic SSW and the ionospheric variations in the American southern middle latitude were detected. Upper thermosphere circulation anomaly and the enhanced semi-diurnal lunitidal influence during the SSW may be crucial to such connection.

How to cite: Liu, J. and Zhang, D.: Ionospheric perturbations in the American southern middle latitude during the Sudden Stratosphere Warming events, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12121, https://doi.org/10.5194/egusphere-egu23-12121, 2023.

EGU23-12894 | ECS | Orals | ST3.4

Altitude extension of NCAR-TIEGCM (TIEGCM‑X) and evaluation 

Yihui Cai, Xinan Yue, Wenbin Wang, Shun‑Rong Zhang, Huixin Liu, Dong Lin, Haonan Wu, Jia Yue, Sean L. Bruinsma, Feng Ding, Zhipeng Ren, and Libo Liu

The upper boundary height of the traditional community general circulation model of the ionosphere‑thermosphere system is too low to be applied to the topside ionosphere/thermosphere study. In this study, the National Center for Atmospheric Research Thermosphere‑Ionosphere‑Electrodynamics General Circulation Model (NCAR‑TIEGCM) was successfully extended upward by four scale heights from 400–600 km to 700–1200 km depending on solar activity, named TIEGCM‑X. The topside ionosphere and thermosphere simulated by TIEGCM‑X agree well with the observations derived from a topside sounder and satellite drag data. In addition, the neutral density, temperature, and electron density simulated by TIEGCM‑X are morphologically consistent with the NCAR‑TIEGCM simulations before extension. The latitude‑altitude distribution of the equatorial ionization anomaly derived from TIEGCM‑X is more reasonable. During geomagnetic storm events, the thermospheric responses of TIEGCM‑X are similar to TIEGCM. However, the ionospheric storm effects in TIEGCM-X are stronger than those in TIEGCM and are even opposites at some middle and low latitudes due to the presence of more closed magnetic field lines. DMSP observations prove that the ionospheric storm effect of TIEGCM-X is more reasonable. The well‑validated TIEGCM‑X has significant potential applications in ionospheric/thermospheric studies, such as the responses to storms, low‑latitude dynamics, and data assimilation.

How to cite: Cai, Y., Yue, X., Wang, W., Zhang, S., Liu, H., Lin, D., Wu, H., Yue, J., Bruinsma, S. L., Ding, F., Ren, Z., and Liu, L.: Altitude extension of NCAR-TIEGCM (TIEGCM‑X) and evaluation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12894, https://doi.org/10.5194/egusphere-egu23-12894, 2023.

EGU23-12901 | Posters virtual | ST3.4

Variations of tidal waves in the Mesosphere and Lower Thermosphere over China region 

Na Li, Jinsong Chen, Xiaobin Wang, Zhimei Tang, and Zonghua Ding

Wind observations by Meteor radars from the year of 2009 to 2018 are utilized to knowledge the climatological characteristics at Mohe (53.1N), Beijing (40.3N), Wuhan (30.5N), Kunming (25.6N) and Sanya (18N). The tidal components with the period of 24h (diurnal), 12h (semidiurnal) are derived by the decomposition of observations using harmonic fitting method. The results show that the magnitude of diurnal tidal amplitude in the zonal and meridional winds increases with decreasing latitude, especially for the meridional wind. Annual and semi-annual changes dominate the main features. However, large difference of annual and semi-annual changes between the zonal and meridional could be seen clearly. Moreover, the diurnal tidal amplitude in the zonal wind at Mohe shows opposite changes above 90km and below 88 km, which is that the amplitude displays large value below 88km during February and March, while small value is prevailing above 90km during this time. When the diurnal amplitude above 90km is large accompanying with small value below 88 km. For the semidiurnal tide, the annual variation is clearly found for the zonal and meridional winds in their amplitudes at all stations. Meanwhile, the magnitude of semidiurnal tidal amplitude decreases with decreasing latitude, and that of meridional amplitude is larger than that of zonal amplitude. At all stations, the zonal diurnal tidal amplitude at Wuhan is largest above 88km in Spring and 94 km in Summer, that at Kunming is largest below 92 km in autumn and winter. The meridional diurnal amplitude at Sanya is biggest above 88 km in four seasons, and that at Kunming is biggest below 86 km in four seasons. For all seasons, the amplitudes in the zonal and meridional winds at Mohe are smallest. For the zonal wind, semidiurnal tidal amplitude at Beijing is largest at 82 – 94 km in Spring, 82 – 96 km in Summer, above 92 km in Autumn. Meantime, the semidiurnal tidal amplitude at Mohe is larger above 94 km and below 82 in Spring, above 96 km and 82 km in Summer, below 90 km in Autumn and at all heights in Winter. Simultaneously, the semidiurnal tidal amplitude at Sanya is smallest in Spring, Summer, Autumn and above 98 km in Winter. However, the variation of meridional semidiurnal tidal amplitude becomes complicated.

How to cite: Li, N., Chen, J., Wang, X., Tang, Z., and Ding, Z.: Variations of tidal waves in the Mesosphere and Lower Thermosphere over China region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12901, https://doi.org/10.5194/egusphere-egu23-12901, 2023.

EGU23-14172 | Posters on site | ST3.4

Search for dependence of ionospheric parameters on meteorological local storms 

Katerina Potuznikova, Petra Koucka Knizova, Jaroslav Chum, and Jacek Kerum

In our recent studies, we analysed coherency between the dynamics of tropospheric low-pressure areas on side and stratospheric and ionospheric variability on the other side. We have identified different types of atmospheric frontal movements in the troposphere associated with particular types of echo detected up to the F2 ionospheric layer on the digisonde measurements (ionograms, drifts) and Continuous Doppler sounder spectrograms. We found that, in addition to synoptic patterns of continental scale, disturbances in the ionosphere are caused by fast-moving midlatitudes frontal cyclones.

Another type of tropospheric situation, which especially in the summer causes observable changes in ionosphere parameters, are local storms caused by thermal convection possibly supported by local orography. The response of these storms in the ionosphere is significant despite the fact that they are meteorological phenomena of the subsynoptic scale (horizontal range of the unit km) and their duration does not exceed several hours).

In the present paper we focus on cases of meteorological storms that occurred in the period from 2014 to 2022 during low geomagnetic and solar activity. The selection of storm events was made based on measurements of both aerological data and surface meteorological data. Automatic detection of spread in hight and frequency in ionograms recorded by the DPS-4D digisonde is performed using convolutional neural network coded in python with help of the tensorflow library.

How to cite: Potuznikova, K., Koucka Knizova, P., Chum, J., and Kerum, J.: Search for dependence of ionospheric parameters on meteorological local storms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14172, https://doi.org/10.5194/egusphere-egu23-14172, 2023.

EGU23-15306 | ECS | Posters virtual | ST3.4

Significant extension of the mesospheric Na layer bottom observed by a full-diurnal-cycle lidar 

Yuan Xia, Jing Jiao, Satonori Nozawa, Xuewu Cheng, Jihong Wang, Chunhua Shi, Lifang Du, Yajuan Li, Haoran Zheng, Faquan Li, and Guotao Yang

Based on the full-diurnal-cycle sodium (Na) lidar observations at Beijing (40.41°N, 116.01°E), we report pronounced downward extensions of the Na layer bottomside to below 75 km near mid-December, 2014. Considerable Na atoms were observed even as low as ~72 km, where Na atoms is short-lived. More interestingly, an unprecedented Na density of ~2500 atoms/cm3 around 75 km was observed on December 17, 2014. Such high Na atoms concentration was two orders of magnitude larger than that normally observed at the similar altitude region. Liberation of Na atoms from its reservoir (e.g., NaHCO3) near the Na layer bottom via neutral chemical reactions, which are accelerated by the largely increased temperature and concentrations of atomic H and O, is suggested to be the critical production mechanism of the enhanced Na layer below 75 km. The diurnal lidar measurements of the Na layer, zonal wind results from a nearby meteor radar, global satellite observations as well as reanalysis data presented here reveal the close correlation between the variation of Na layer bottom and planetary scale atmospheric processes. The longitudinal distributions of geopotential amplitudes of PW show that there exists unusual development of the amplitude of PW2, and the stratosphere near the lidar location is dominated by PW2 trough in mid-December. The out-of-phase temperature anomalies in the upper stratosphere and upper mesosphere are likely due to the modulation of GW filtering by stratosphere wind. The strong eastward wind in the upper stratosphere provides a favorable condition for the vertical propagation of westward GWs. Westward forcing could induce a poleward flow and drive downward circulation in the mesosphere, leading to adiabatic heating. Furthermore, the bottom enhancement on December 17, 2014 was also accompanied by clear wavy signatures in the main layer. The unprecedented Na density of ~2500 cm-3 near 75 km observed on December 17, 2014 is also greatly contributed by the adiabatic vertical motion of air parcel forced by the superposition of tide and GW.

These results provide a clear observational evidence for the Na layer bottom response to the planetary-scale atmospheric perturbations in addition to tide and GW through affecting the chemical balance. These results also have implications for the response of the metal layer to vertical coupling between the lower atmosphere and the mesosphere.

How to cite: Xia, Y., Jiao, J., Nozawa, S., Cheng, X., Wang, J., Shi, C., Du, L., Li, Y., Zheng, H., Li, F., and Yang, G.: Significant extension of the mesospheric Na layer bottom observed by a full-diurnal-cycle lidar, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15306, https://doi.org/10.5194/egusphere-egu23-15306, 2023.

EGU23-16212 | Posters virtual | ST3.4

First Simultaneous Lidar Observations of Thermosphere-Ionosphere Sporadic Ni and Na (TISNi and TISNa) Layers (∼105–120 km) Over Beijing (40.42°N, 116.02°E) 

Fuju Wu, Xinzhao Chu, Lifang Du, Jing Jiao, Haoran Zheng, Yuchang Xun, Wuhu Feng, John M. C. Plane, and Guotao Yang

We report the first simultaneous lidar observations of thermosphere-ionosphere sporadic nickel and Na (TISNi and TISNa) layers in altitudes ∼105–120 km over Yanqing (40.42°N, 116.02°E), Beijing. From two years of data spanning April 2019 to April 2020 and July 2020 to June 2021, TISNi layers in May and June possess high densities with a maximum of 818 cm −3 on 17 May 2021, exceeding the density of main layer peak (∼85 km) by ∼4 times. They correlate with strong sporadic E layers observed nearby. TISNa layers occur at similar altitudes as TISNi with spatial-temporal correlation coefficients of ∼1. The enrichment of Ni in TISNi is evident as the [TISNi]/[TISNa] column abundance ratios are ∼1, about 10 times the main layer [Ni]/[Na] ratios. These results are largely explained by neutralization of converged Ni + and Na + ions via recombination with electrons. Calculations show direct recombination dominating over dissociative recombination above ∼105 km.

How to cite: Wu, F., Chu, X., Du, L., Jiao, J., Zheng, H., Xun, Y., Feng, W., Plane, J. M. C., and Yang, G.: First Simultaneous Lidar Observations of Thermosphere-Ionosphere Sporadic Ni and Na (TISNi and TISNa) Layers (∼105–120 km) Over Beijing (40.42°N, 116.02°E), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16212, https://doi.org/10.5194/egusphere-egu23-16212, 2023.

EGU23-16536 | Orals | ST3.4

Tonga eruption-induced disturbances in lithosphere, atmosphere, and ionosphere and their coupling 

Yang-Yi Sun, Chieh-Hung Chen, Xuemin Zhang, Yongxin Gao, and Jann-Yenq Liu

The explosive eruption of the Tonga underwater volcano (20.53°S, 175.38°W) occurred at ~04:15 UT on 15 January 2022. In this study, the networks of ground-based barometers, magnetometers, and global navigation satellite system (GNSS) receivers recorded disturbances that traveled away from the eruption with acoustic speeds in the atmosphere and ionosphere. The primary disturbances with periods of several hours in the magnetic fields and total electron content (TEC) observations reveal the electrodynamics changes in the upper atmosphere and the coupling of E- and F-region dynamo. The atmospheric Lamb wave propagating upward caused the secondary waves in the ionosphere and seeds irregularities following the leading front of the primary disturbances. The global radio occultation technique onboard the FORMOSAT‐7/COSMIC2 (F7/C2) mission sounds the ionosphere in the vertical direction, which shows the large-scale disturbances with scale > 200 km in the ionospheric F region and irregularities. On the other hand, the co-located instruments, including a seismometer, atmospheric electric field meter, wind profile radar, magnetometer, and GNSS receiver, monitored perturbations in the lithosphere, atmosphere, and ionosphere simultaneously at a certain location (29°N, 103°E) that is ~ten thousands of kilometers northwest away from the eruption. The primary phenomena of the eruption-associated disturbances are the long-period changes (period of ~ 2 hr) in the ionospheric TEC and the magnetic field in the upper atmosphere (above 100 km altitude), indicating the interactions of the ionospheric electrodynamics. The secondary phenomena included wind disturbances in the troposphere, which contribute to short-period changes (up to ten minutes) in air pressure, ground vibrations, and atmospheric electric field. The near-surface disturbances propagating upward further triggered short-period variations in the geomagnetic field and TEC. The primary changes in ionospheric electrodynamics, wind disturbance in the lower atmosphere, its upward propagation, and the resonance reveal the complex coupling phenomena due to the eruption and enrich our understanding of the geosphere coupling.

How to cite: Sun, Y.-Y., Chen, C.-H., Zhang, X., Gao, Y., and Liu, J.-Y.: Tonga eruption-induced disturbances in lithosphere, atmosphere, and ionosphere and their coupling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16536, https://doi.org/10.5194/egusphere-egu23-16536, 2023.

The polar mesospheric clouds (PMCs) obtained from Aeronomy of Ice in the Mesosphere (AIM)/Cloud Imaging and Particle Size (CIPS) and Himawari-8/Advanced Himawari Imager (AHI) observations are analyzed for the multi-year climatology and interannual variations. The PMCs dependence on mesospheric temperature and water vapor (H2O) are further investigated with data from Microwave Limb Sounder (MLS). Our analysis shows that PMCs onset date and occurrence rate are strongly dependent on the atmospheric environment, i.e. underlying seasonal behavior of temperature and water vapor. Upper-mesospheric dehydration by PMCs is evident in MLS water vapor observations, The spatial patterns of the depleted water vapor resemble the PMCs distribution over the Arctic and Antarctic region during the days after summer solstice. Year-to-year variabilities of the PMCs occurrence rate and onset date are highly correlated with the mesospheric temperature and H2O variations, particularly in the southern hemisphere (SH). The global increase of mesospheric H2O during the last decade may explain the increased PMCs occurrence in the northern hemisphere (NH). Although mesospheric temperature and H2O exhibits a strong 11-year variation, little solar cycle signature is found in the PMCs occurrence during 2005-2021.

How to cite: Lee, J. and Wu, D.: The Sensitivity of Polar Mesospheric Clouds to Mesospheric Temperature and Water Vapor, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-907, https://doi.org/10.5194/egusphere-egu23-907, 2023.

EGU23-1177 | ECS | Orals | ST3.5

Simultaneous observations of mesospheric bore and front over the Himalaya 

Subarna Mondal, Amitava Guharay, Sumanta Sarkhel, M. V. Sunil Krishna, and Martin G. Mlynczak

Interesting observational evidence of interaction between a mesospheric bore and a mesospheric front is found in O(1S) 557.7 nm airglow images over the western Himalayan region on 25 April 2022. The event is unique as it is the first report of a mesospheric bore interacting with a typical mesospheric front. The vertical profiles of temperature and Brunt Vaisala frequency indicate presence of a strong mesospheric inversion layer (MIL) which acts as a stable thermal duct for the propagation of the mesospheric bore. Analysis suggests that local chemical heating plays a significant role in sustaining a strong MIL/thermal duct. The bore front shows an anti-clockwise rotation, which is attributed to the differential phase speed of different regions of the bore due to variations in duct depth. The bore propagation above is observed to push the underlying OH layer downward, resulting in a maximum horizontal slope of the peak height of the OH volume emission rate (VER) on 25 April 2022. The results highlight the bore-front interaction, mesospheric background condition for bore propagation, and its effect on the altitudinal shift of adjacent airglow emission layers.

How to cite: Mondal, S., Guharay, A., Sarkhel, S., Krishna, M. V. S., and Mlynczak, M. G.: Simultaneous observations of mesospheric bore and front over the Himalaya, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1177, https://doi.org/10.5194/egusphere-egu23-1177, 2023.

Tektites are a naturally occurring form of cosmic impact ejecta, produced in ~ 2 or 3% of impact events from melted and mixed silicate sediments that are launched into space where they devolatilize and quench to solid glass.  Australasian tektites (AAT) make up the largest and most recent of the known tektite strewnfields, covering ~1/4 of Earth’s surface with 30 to 60 billion tons of melt glass.  In southeast Asia, the Indochinite sub-family of these glassy objects appear mainly as fractured and sometimes contorted fragments of formerly hollow spheroid predecessors.  Surface textures, bulk and detailed morphometrics of Indochinite fragment-form tektites record a tortured history that is not consistent with mere hypersonic atmospheric reentry into a standard atmospheric column.  The tektites show rapid bulk reheating and surface effects consistent with high-voltage arcing disruption.  The overall region where these fragment-form tektites fell has a surface that was laterized within hours of their arrival, pulsed with heat and moisture to the point of degrading the rocks and soil the tektites lie within.  Clear ablation signatures on symmetric ablated spheroid AAT of Australia and the Central Indian Ocean basin indicate their source as the N. American Great Lakes region.  The Marine Isotope Stage MIS20 epoch (deep ice age) of the event and Michigan Basin geology suggest several thousand cubic km of disrupted Laurentide Ice Sheet may have been injected across the exosphere via oblique ricochet impact, lingering as degenerate byproducts for a day or more.  High-potential E-field and regional disruption of the atmospheric column from exosphere to surface over southeast Asia is indicated.

How to cite: Harris, T.: Impact ejecta glass records atmospheric columnar disruption and strong E-field, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4027, https://doi.org/10.5194/egusphere-egu23-4027, 2023.

EGU23-4415 | ECS | Orals | ST3.5

On the Correlation between the sodium in the MLT and meteor radiant distribution 

Yanlin Li, Tai-Yin Huang, Julio Urbina, Fabio Vargas, and Wuhu Feng

The sodium layer in the mesosphere and lower thermosphere (MLT) region is originated from meteoroid mass deposits produced by its ablation. Understanding the correlation between the meteoroid material input and the concentration of the sodium layer is essential for many investigations that use sodium as a tracer to study the dynamics in the MLT. A new numerical sodium chemistry model has been developed to study such correlation, and the results are cross-compared to the meteoroid material input inferred from the recently revealed sporadic meteor radiant distribution derived from the data gathered by the Arecibo Observatory. The sodium chemistry model is computationally efficient, runs in high-time resolution, and the sodium-bearing species are equally treated in the continuity equation devoid of making any steady-state approximation. This work will also present the seasonal and latitudinal distribution of meteoroid injection rates derived from the aforementioned sporadic meteor radiant distribution.Our simulation results agreed with the general feature of the measurements obtained from the Colorado State University Lidar (CSU) and the Andes Lidar Observatory (ALO) but with variations three times smaller.

How to cite: Li, Y., Huang, T.-Y., Urbina, J., Vargas, F., and Feng, W.: On the Correlation between the sodium in the MLT and meteor radiant distribution, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4415, https://doi.org/10.5194/egusphere-egu23-4415, 2023.

EGU23-4518 | Posters on site | ST3.5

Understanding the Coupled OH Meinel and O2 Atmospheric Band Nightglow Emissions 

Konstantinos S. Kalogerakis

Nightglow emission signatures observed from space- and ground-based instruments are commonly used as proxies for atmospheric composition, especially for the altitude region around 100 km that cannot be easily studied in situ. Monitoring the intensity and temporal evolution of such proxies by remote sensing is often the method of choice to study a plethora of phenomena in this region of the atmosphere. Thus, the quantitative details relevant to the production and deactivation of excited atomic and molecular precursors responsible for prominent nightglow emissions are required to study atmospheric composition, radiative and energy balance, wave propagation and dissipation, as well as transport dynamics. Significant gaps and uncertainties exist in the understanding of the above processes and, as our recent studies on nightglow emissions revealed, substantial revisions of the relevant atmospheric models are warranted.

We will present a progress report on our efforts to advance the understanding of key mesospheric nightglow emissions by investigating the recently established coupling between the OH Meinel and the O2 Atmospheric band emissions, mediated by collisions of O atoms with vibrationally excited OH.

This work is supported by the U.S. National Science Foundation (NSF) under Grants AGS-2009960 and AGS-2113888.

How to cite: Kalogerakis, K. S.: Understanding the Coupled OH Meinel and O2 Atmospheric Band Nightglow Emissions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4518, https://doi.org/10.5194/egusphere-egu23-4518, 2023.

EGU23-5246 | Posters on site | ST3.5

Scientific Highlights from ROMIC 

Franz-Josef Lübken

The German Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung, BMBF) has launched a research initiative in 2013/2014 called ROMIC (Role of the Middle Atmosphere in Climate). The second phase of this project extends until 2024. The aim of ROMIC is to improve our understanding of long term variations in the stratosphere, mesosphere, and lower thermosphere and to investigate their potential role for
climate changes in the troposphere. This includes to study coupling mechanisms between various layers and the relative importance of anthropogenic and natural forcing, e.\ g., by the Sun. Scientists at a total of 13 research institutes in Germany are involved and cover a large range of experimental and theoretical topics relevant for ROMIC. Most projects are linked to international activities and cooperations. Some scientific highlightsfrom the research projects within ROMIC will be presented.

How to cite: Lübken, F.-J.: Scientific Highlights from ROMIC, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5246, https://doi.org/10.5194/egusphere-egu23-5246, 2023.

EGU23-5587 | Orals | ST3.5

Empirical modelling of SSUSI-derived auroral ionization rates 

Stefan Bender, Patrick Espy, and Larry Paxton

Solar, auroral, and radiation belt electrons enter the atmosphere at polar regions leading to ionization and affecting its chemistry. Climate models with interactive chemistry in the upper atmosphere, such as WACCM-X or EDITh, usually parametrize this ionization and calculate the related changes in chemistry based on satellite particle measurements. Widely used particle data are derived from the POES and GOES satellite measurements which provide electron and proton spectra. These satellites provide in-situ measurements of the particle populations at the satellite altitude, but require interpolation and modelling to infer the actual input into the upper atmosphere.

Here we use the electron energy and flux data products from the Special Sensor Ultraviolet Spectrographic Imager (SSUSI) instruments on board the Defense Meteorological Satellite Program (DMSP) satellites. This formation of currently three operating satellites observes both auroral zones in the far UV from (115--180 nm) with a 3000 km wide swath and 10 x 10 km (nadir) pixel resolution during each orbit. From the N2 LBH emissions, the precipitating electron energies and fluxes are inferred in the range from 2 keV to 20 keV. We use these observed electron energies and fluxes to calculate auroral ionization rates in the lower thermosphere (≈ 90–150 km), which have been validated previously against ground-based electron density measurements
from EISCAT. We present an empirical model of these ionization rates derived for the entire satellite operating time and sorted according to magnetic local time and geomagnetic latitude. The model is based on geomagnetic and solar flux indices, and the coefficients indicate where certain drivers have the largest influence. The model will be particularly targeted for use in climate models that include the upper atmosphere, such as the aforementioned WACCM-X or EDITh models, and we present an initial comparison to current implementations for ionization rates used in high-top whole-atmosphere models. Further applications include the derived conductances in the auroral region, as well as modelling and forecasting E-region disturbances related to Space Weather.

How to cite: Bender, S., Espy, P., and Paxton, L.: Empirical modelling of SSUSI-derived auroral ionization rates, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5587, https://doi.org/10.5194/egusphere-egu23-5587, 2023.

EGU23-7129 | Orals | ST3.5

The role of stratified turbulence in the cold summer mesopause region 

Victor Avsarkisov and Federico Conte

The primary physical mechanism behind the formation of the summer mesopause at middle and high latitudes is related to atmospheric gravity waves. An insight into this extreme thermal phenomenon can be gained from investigating the mesoscale energy spectrum. In this work, we decompose the frequency spectrum into divergent and rotational parts and find that their energy contributions are equipartitioned at high frequencies. This mesoscale energy equipartition indicates the effect of stratified turbulence. Analysis of the power spectra of observed and simulated horizontal winds at middle latitudes reveals the role of stratified turbulence in the formation of the summer mesopause region.

How to cite: Avsarkisov, V. and Conte, F.: The role of stratified turbulence in the cold summer mesopause region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7129, https://doi.org/10.5194/egusphere-egu23-7129, 2023.

Atmospheric gravity waves transport energy and momentum through the atmosphere and can travel large horizontal and vertical distances from the troposphere to the mesosphere and higher. They contribute to atmospheric dynamics and among others drive the meridional pole-to-pole circulation in the mesosphere. Thus, knowing about gravity waves, their spatio-temporal characteristics, their interaction with other waves and the atmospheric background is attracting more and more attention in order to further improve climate and even meteorological models.

In the upper mesosphere / lower thermosphere (UMLT) region around an altitude of 80km to 100km, OH airglow can be utilized for passive remote sensing and continuous nightly observations of atmospheric dynamics, especially of gravity waves. The OH airglow layer is a chemiluminescent layer with a strong emission in the short wave infrared spectral range (at about 1500nm) and is located at an altitude of about 86-87km with a layer halfwidth of about 4km. The OH airglow intensity is modulated by traversing atmospheric gravity waves which lead amongst others to a vertical transport of atomic oxygen. Observing the OH airglow with short-wave infrared imagers allows characterizing gravity waves. From these observations the horizontal wave parameters (horizontal wavelength, horizontal direction of propagation, etc.) can be derived.

In this study we present measurements of two ground-based FAIM (Fast Airglow IMager) systems, which are cameras sensitive in the short-wave infrared region observing the OH airglow layer with a high temporal resolution. The cameras are located at Oberpfaffenhofen, Germany and Otlica, Slovenia, about 300km apart from each other and are pointing to the same volume at about 87km located in the Alpine Region above Northern Italy. We developed a novel tomographic algorithm to allow for a three-dimensional reconstruction of the airglow layer by combining images from the two viewing angles. In order to solve the highly underdetermined equation system, prior knowledge of the OH airglow layer vertical profile is needed e.g. from multi-year observations of SABER on the TIMED satellite on a statistical basis, or Gaussian and Chapman basis functions. This allows us, among others, to derive the vertical wavelength of the waves, their three-dimensional propagation direction, and their three-dimensional structure. From that knowledge, further wave parameters but also the horizontal wind along the wave propagation can be estimated via the wave’s dispersion relation.

We will explain the tomographic reconstruction method, its capabilities and limits and will present a detailed case study showing a 3D-reconstructed gravity wave and the derivation of its parameters.

This work received funding from the Bavarian State Ministry of the Environment and Consumer Protection.

How to cite: Hannawald, P., Noll, S., Wüst, S., and Bittner, M.: 3D reconstruction of atmospheric gravity waves and derivation of vertical wave parameters with tomography applied to data from two ground-based cameras observing OH airglow, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7554, https://doi.org/10.5194/egusphere-egu23-7554, 2023.

EGU23-8477 | Posters on site | ST3.5

X-shooter-based climatologies of intensity, solar cycle effect, and residual variability for 298 OH lines 

Stefan Noll, Carsten Schmidt, Wolfgang Kausch, Michael Bittner, and Stefan Kimeswenger

The line emission from the various roto-vibrational bands of the OH radical is an important tracer of the chemistry and dynamics in the Earth's nocturnal mesopause region between about 80 and 100 km. As most studies have focused either on a few bright lines or integrated emission from relatively wide wavelength windows, there is still a lack of knowledge with respect to the variability of faint lines from high rotational levels as well as the change of the variability patterns depending on the line parameters, which influence the effective emission height. Thanks to a large data set of about 90,000 near-infrared X-shooter spectra taken at Cerro Paranal in Chile within a time interval of 10 years, we have been able to derive line-specific climatologies of intensity, solar cycle effect, and residual variability for local time and day of year based on a set of 298 OH lines. Our analysis of the derived climatologies involves different decomposition techniques, the study of the variance depending on the time scale of the perturbation, and the calculation of correlations for the line dependence of different properties. The considered effective line emission heights originate from the investigation of the propagation of a strong quasi-2-day wave in 2017 using the X-shooter and space-based SABER data. Our results for the entire X-shooter data set reveal the importance of the mixing of thermalised and non-thermalised rotational populations for the amplitude of a perturbation as well as a shift of the climatological variability patterns with local time depending on the emission height. The latter implies a strong influence of the migrating diurnal tide and causes significant line-dependent differences in the effective solar cycle effect, which mainly depends on the solar forcing in the austral winter.

How to cite: Noll, S., Schmidt, C., Kausch, W., Bittner, M., and Kimeswenger, S.: X-shooter-based climatologies of intensity, solar cycle effect, and residual variability for 298 OH lines, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8477, https://doi.org/10.5194/egusphere-egu23-8477, 2023.

EGU23-8579 | ECS | Posters on site | ST3.5

Long-term study of the summer wind variability in the mesosphere and lower thermosphere over nearly two decades at middle and high latitudes 

Juliana Jaen, Toralf Renkwitz, Jorge Chau, Huixin Liu, Christoph Jacobi, Masaki Tsutsumi, and Njål Gulbrandsen

Winds at the mesosphere and lower thermosphere have been measured by partial reflection radars and specular meteor radars for almost two decades (2004-2022) over Germany and Norway (i.e., middle and high latitudes, respectively). Continuous wind measurements during the mentioned period are important to understand their long-term behavior. The zonal mean wind climatology displays an eastward wind during the winter months and a westward summer jet below ~85km at middle latitudes (~90km at high latitudes). Above the mentioned height, an eastward wind jet is observed. In the meridional wind component, the southward summer wind displays amplitudes between 4 and 5 times less intense than the westward jet. We studied the intensity of the summer wind components, the long-term variability and the possible connection to external forcing (i.e. El Niño-Southern Oscillation, and quasi-biennial oscillation, solar activity and geomagnetic activity). Analyzing the summer winds for low and high geomagnetic activity classified with the Ap index, there is a significant difference between both cases suggesting disturbances in the wind due to high geomagnetic activity. The long-term study shows significant trends at middle latitudes in the monthly summer values of the westward summer jet. As a consequence of the increase in the westward wind, a decrease in the southward component is observed at the same latitudes. While at high latitudes the eastward jet shows a decreasing velocity during July.

How to cite: Jaen, J., Renkwitz, T., Chau, J., Liu, H., Jacobi, C., Tsutsumi, M., and Gulbrandsen, N.: Long-term study of the summer wind variability in the mesosphere and lower thermosphere over nearly two decades at middle and high latitudes, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8579, https://doi.org/10.5194/egusphere-egu23-8579, 2023.

EGU23-11006 | ECS | Orals | ST3.5 | Highlight

One year of MLT dynamics over central and northern Peru from SIMONe systems 

Federico Conte, Jorge Chau, Erdal Yiğit, José Suclupe, Karim Kuyeng, and Rodolfo Rodríguez

One year of Spread spectrum Interferometric Multistatic meteor radar Observing Network (SIMONe) measurements are analyzed and compared for the first time between two low-latitude locations in Peru: Jicamarca (12°S, 77°W) and Piura (5°S, 80°W). Investigation of the mean horizontal winds and tides reveals that mesosphere and lower thermosphere (MLT) planetary-scale dynamics are similar between these two locations, although differences can be seen in some tidal components, e.g., the diurnal tide. On the other hand, monthly median values of the 4-hour, 4-km momentum fluxes indicate that the mesoscale dynamics differ significantly between Jicamarca and Piura. These differences are particularly evident during the (southern hemisphere’s) summertime in the zonal component, where a strong acceleration of the background wind by westward-propagating gravity waves (GWs) is observed at all altitudes (80-100 km) only over Piura. The latter finding observationally confirms the previous studies based on model simulations indicating that the directions of the GW drag and the background wind coincide in the low-latitude MLT [Yiğit & Medvedev, 2017].

How to cite: Conte, F., Chau, J., Yiğit, E., Suclupe, J., Kuyeng, K., and Rodríguez, R.: One year of MLT dynamics over central and northern Peru from SIMONe systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11006, https://doi.org/10.5194/egusphere-egu23-11006, 2023.

EGU23-13908 | ECS | Orals | ST3.5 | Highlight

Energetic Particle Precipitation reflected in the Global Secondary Ozone Distribution 

Jia Jia, Lisa E. Murberg, Tiril Løvset, Yvan J. Orsolini, Patrick J. Espy, Jude Salinas, Jae N. Lee, Dong Wu, and Jiarong Zhang

The secondary ozone layer is a global peak in ozone abundance in the upper mesosphere-lower thermosphere (UMLT) around 90-95 km. The effect of energetic particle precipitation (EPP) from geomagnetic processes on this UMLT ozone has not been well studied. In this research we investigated how the secondary ozone response to EPP from the Microwave Limb Sounder (MLS) and the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Aura and TIMED satellites, respectively. In addition, the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension and specified dynamics (SD-WACCM-X) was used to characterize the residual circulation during EPP events. By comparing ozone and circulation changes under High- and low-Ap conditions, we report regions of secondary ozone enhancement or deficit across low, mid and high latitudes as a result of circulation and transport changes induced by EPP.

How to cite: Jia, J., Murberg, L. E., Løvset, T., Orsolini, Y. J., Espy, P. J., Salinas, J., Lee, J. N., Wu, D., and Zhang, J.: Energetic Particle Precipitation reflected in the Global Secondary Ozone Distribution, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13908, https://doi.org/10.5194/egusphere-egu23-13908, 2023.

EGU23-13994 | Posters on site | ST3.5

The impact of extreme solar events on the atmosphere 

Thomas Reddmann, Monali Borthakur, Miriam Sinnhuber, Ilya Usoskin, Jan Maik Wissing, and Jan Maik Wissing

Besides the well-known 11 year solar cycle, the Sun occasionally produces strong eruptions on the Sun‘s surface and in the corona. They can first be seen as flare events in electromagnetic spectrum down to X ray wavelengths. Within these strong eruptions, particles in the solar plasma, mainly protons, are accelerated to high energies that hit the Earth within hours after the event. In addition, plasma clouds can be accelerated and ejected into the interplanetary space and, provided they are directed to the Earth, can cause severe geomagnetic disturbances. This results in a further energetic particle precipitation event a few days after the primary solar eruption. The strength of these events spans orders of magnitude, with the strongest having dramatic impact on the ionosphere and the middle atmosphere affecting even human activities. Here we study the chemical impact and dynamical of solar events on the middle atmosphere which are on the very extreme side but still within the range of a one per millennia event.

We first derive a reference example of an extreme solar event from historical records of solar proton events and from analyzed distributions of energy spectra for geomagnetic storms. We then take ionization rates calculated from strong observed events and scale them to represent the extreme events. Finally, we combine the solar proton event with the geomagnetic storm as both events typically impact different parts of the atmosphere. The ionization rates for the extreme event are then used in simulations in the KASIMA and EMAC model which both include energetic particle induced chemistry.In order to represent different dynamical situations in the middle atmosphere which are important for the vertical coupling between the mesosphere-lower thermosphere (MLT) region and the stratosphere we select specific periods of the ERA-Interim dataset with a special focus on sudden stratospheric warmings (SSW) and apply the event for those situations. The simplified production efficiency of NOx and HOx in the models is further compared to an ion chemistry model where the extreme ionization rates are applied. The case of a SSW which shows an elevated stratosphere synchronized with the extreme event is studied in detail as a kind of worst case scenario.

How to cite: Reddmann, T., Borthakur, M., Sinnhuber, M., Usoskin, I., Wissing, J. M., and Wissing, J. M.: The impact of extreme solar events on the atmosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13994, https://doi.org/10.5194/egusphere-egu23-13994, 2023.

Based on the hourly output from the 2000–2014 simulations of the National Center for Atmospheric Research’s vertically extended version of the Whole Atmosphere Community Climate Model in specified dynamics configuration, we examine the roles of planetary waves, gravity waves and atmospheric tides in driving the mean meridional circulation in the lower thermosphere and its response to the sudden stratospheric warming phenomenon with an elevated stratopause in the northern hemisphere. Sandwiched between the two summer-to-winter overturning circulations in the mesosphere and the upper thermosphere, the climatological lower thermosphere mean meridional circulation is a narrow gyre that is characterized by upwelling in the middle winter latitudes, equatorward flow near 120 km, and downwelling in the middle and high summer latitudes. Following the onset of the sudden stratospheric warmings, this gyre reverses its climatological direction, resulting in a “chimney-like” feature of un-interrupted polar descent from the altitude of 150 km down to the upper mesosphere. This reversal is driven by the westward-propagating planetary waves, which exert a brief but significant westward forcing between 70 and 125 km, exceeding gravity wave and tidal forcings in that altitude range. The attendant polar descent potentially leads to a short-lived enhanced transport of nitric oxide into the mesosphere (with excess in the order of 1. parts per million), while carbon dioxide is decreased.

How to cite: Orsolini, Y., Zhang, J., and Limpasuvan, V.: Abrupt Change in the Lower Thermospheric Mean Meridional Circulation during Sudden Stratospheric Warmings and its Impact on Trace Species, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14077, https://doi.org/10.5194/egusphere-egu23-14077, 2023.

EGU23-14102 | Posters on site | ST3.5 | Highlight

Dynamics and variability of the MLT represented by UA-ICON 

Claudia Stolle, Markus Kunze, Tarique Siddiqui, Chistoph Zülicke, Mozhgan Amiramjadi, Yosuke Yamazaki, Gerd Baumgarten, Sebastian Borchert, and Hauke Schmidt

The variability of the upper atmosphere is largely influenced by dynamical forcing from the lower and middle atmosphere. The Mesosphere and Lower Thermosphere (MLT) is the transition region between the middle atmosphere and the upper atmosphere, and it determines dynamical forcing to the upper atmosphere from below. It is thus of high importance to know, describe, and understand the dynamical processes within the MLT to quantify dynamics. Therein, General Circulation Models (GCMs) have been a significant tool to explain MLT processes.

However, developing the right parameterizations that allow to accurately model near-to-realistic states of the MLT by GCMs is challenging, which is reflected in a large diversity of results from different models in comparison to observations, e.g., of winds and temperatures at the MLT.

In recent years, the community model ICON (Icosahedral Nonhydrostatic Weather and Climate Model) has been expanded into altitudes up to 150 km, named the UA (Upper Atmosphere) branch. UA-ICON is increasingly being applied to model and to understand MLT processes and how they are controlled by the lower and middle atmosphere.

We present newly developed capabilities of UA-ICON. Examples are mesospheric cooling during stratospheric warming events, low summer mesopause temperatures through appropriate specification of gravity wave parameterizations and runs of high spatial resolution. Results are discussed in comparison with observations and with predictions by other GCMs.

How to cite: Stolle, C., Kunze, M., Siddiqui, T., Zülicke, C., Amiramjadi, M., Yamazaki, Y., Baumgarten, G., Borchert, S., and Schmidt, H.: Dynamics and variability of the MLT represented by UA-ICON, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14102, https://doi.org/10.5194/egusphere-egu23-14102, 2023.

EGU23-16759 | ECS | Posters virtual | ST3.5

Ionospheric Hole in the MLT Regions after Submarine Volcanic Eruptions 

Sovit Khadka, Cesar Valladares, and Andrew Gerrard

A gigantic submarine volcano erupted near Tonga Island on 15 January 2022 generating a tsunami and related atmospheric and oceanic waves across the globe. This violent volcano triggered extreme disturbances just above the volcanic center that reached near Earth’s stratosphere. This geophysical event generated acoustic-gravity waves to propagate upward and induce significant global perturbations and holes in the mesosphere and lower thermosphere (MLT) regions. Here, we study the MLT region’s response to the Tonga-induced perturbations using ground-based Global Positioning System (GPS)-total electron content (TEC) data from GPS receivers spread in the South American continent. The possible propagation mechanism of the Tonga-related ionospheric holes and perturbations mediated by neutral wind-driven dynamo fields, vertical drifts, and the contribution of geomagnetic conditions will also be discussed. 

How to cite: Khadka, S., Valladares, C., and Gerrard, A.: Ionospheric Hole in the MLT Regions after Submarine Volcanic Eruptions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16759, https://doi.org/10.5194/egusphere-egu23-16759, 2023.

EGU23-16826 | Orals | ST3.5 | Highlight

First light from the MATS satellite 

Ole Martin Christensen, Jörg Gumbel, Linda Megner, Donal Murtagh, Björn Linder, Jonas Hedin, Nickolay Ivchenko, and Jacek Stegman

Global three-dimensional data are a key to understanding gravity waves in the mesosphere and lower thermosphere. MATS is a small Swedish satellite that aims at providing such fields using tomographic measurements of oxygen A-band airglow and noctilucent clouds. MATS was successfully launched from Mahia, New Zealand, on November 4, 2022. Data collection started in December 2022, and MATS is projected to have collected over 3 million images of the MLT region by April 2023.

This presentation will provide an overview over first results from the MATS data. This includes analysis of in-flight performance of the instruments, an overview of data availability, and some examples of possible usage of the data. We will discuss data quality as well as possible biases and uncertainties that need to be considered when using this new and unique dataset for mesospheric studies.

How to cite: Christensen, O. M., Gumbel, J., Megner, L., Murtagh, D., Linder, B., Hedin, J., Ivchenko, N., and Stegman, J.: First light from the MATS satellite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16826, https://doi.org/10.5194/egusphere-egu23-16826, 2023.

EGU23-1198 | Posters on site | ST3.6

Aspect Angle of Plasma Irregularities in the Ionosphere Measured by Using the Radar Imaging of VHF Arrayed Radar 

Jenn-Shyong Chen, Chien-Ya Wang, and Yen-Hsyang Chu

Multireceiver and multifrequency radar imaging techniques, implemented in the 46.5 MHz MU radar in Japan (34.85°N and 136.10°E), were employed to investigate the aspect sensitivity of field-aligned plasma irregularities (FAIs) in the mid-latitude ionospheric E region. Aspect sensitivity of refractive irregularities in the atmosphere describes the radar echo intensity varying with the radar beam direction. For the FAIs in the ionosphere, the radar echoes are generally strongest at the beam direction perpendicular to the geomagnetic field line, and decay rapidly with off-perpendicular angle along the geomagnetic field line. This feature relates partly with the values of electron-neutral collision frequency (νe), electron gyrofrequency (Ωe), ion-neutral collision frequency (νi), ion gyrofrequency (Ωi), the ratio νee, among others, and moreover, is also subjected to nonlinear coupling process of unstable waves in the plasma irregularities. In practical observation, the radar beam of the MU radar was directed to geographic north and at 51° zenith angle, which was normal to the geomagnetic field line around 100-110 km height (range: ~160-175 km along the beam direction). Five carrier frequencies and nineteen receivers were operated for radar imaging to retrieve the power distribution in the radar volume, and then the angular power distribution was used to estimate the aspect angle along the geomagnetic field line. Retrieval algorithms such as Fourier, Capon, and norm-constrained Capon (NC-Capon) were utilized, in which the NC-Capon was applied to FAIs for the first time and found to be more suitable for the present study. The aspect angles estimated by the NC-Capon algorithm ranged between 0.1° and 0.4° mostly, which are close to the previous measurements with the radar interferometry (RI) made for the lower mid-latitude sporadic E region and the equatorial electrojet irregularities.

How to cite: Chen, J.-S., Wang, C.-Y., and Chu, Y.-H.: Aspect Angle of Plasma Irregularities in the Ionosphere Measured by Using the Radar Imaging of VHF Arrayed Radar, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1198, https://doi.org/10.5194/egusphere-egu23-1198, 2023.

EGU23-1306 | ECS | Posters on site | ST3.6

Energy deposition of a Pc5 ULF wave in the polar ionosphere measured by EISCAT 

Charlotte M. van Hazendonk, Lisa Baddeley, and Karl M. Laundal

Ultra low frequency (ULF) waves can contribute significantly to energy and momentum transfer between the Solar Wind – magnetosphere – ionosphere system, however, the energy deposition by ULF waves is often not taken into account in the global energy budget. A case study of spatial and temporal energy deposition of a Pc5 (2 – 7 mHz) ULF wave during non-sunlit conditions is presented. Datasets from the EISCAT Tromsø VHF radar, magnetometers and DMSP satellites were utilized to estimate the wave characteristics and the height-dependent energy deposition rates. The equipartition of energy into the ionosphere through thermal, ion frictional and/or Joule heating are discussed. The goal of this study is to quantify how much energy is deposited by ULF waves in otherwise quiet conditions.

How to cite: van Hazendonk, C. M., Baddeley, L., and Laundal, K. M.: Energy deposition of a Pc5 ULF wave in the polar ionosphere measured by EISCAT, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1306, https://doi.org/10.5194/egusphere-egu23-1306, 2023.

EGU23-2156 | ECS | Orals | ST3.6

Development of a Helium Resonance Lidar for the Upper Thermosphere 

Christopher Geach, Bernd Kaifler, Hans Christian Büdenbender, Andreas Mezger, and Markus Rapp

Resonance lidars targeting fluorescence lines of metallic layers in the mesosphere and lower thermosphere have long been used to measure profiles of wind and temperature [1], most recently achieving a maximum altitude of 300 km [2], but the rapidly decreasing densities of these metallic species prevents measurements at higher altitudes.

An alternative, first proposed in 1997 [3], is an extension of this technique to metastable helium, which would increase the possible range of resonance lidar measurements to 1000 km or higher. Last year, for the first time, a helium resonance lidar system was realized at the German Aerospace Center (DLR) in southern Germany [4]. The initial measurements by this instrument, made last year between January and March, captured the first profiles of metastable helium density, extending to an altitude of 700 km.              

We present an overview of this lidar system; we report an update on its status, including the results of the second measurement campaign; and we discuss the potential for wind and temperature measurements given anticipated improvements to system performance.

 

[1] Fricke, K. & von Zahn, U. (1985) Mesopause temperatures derived from probing the hyperfine structure of the D2 resonance line of sodium by lidar. J. Atmos. Terrestrial Phys. 47, 499–512.

[2] Jiao, J., Chu, X., Jin, H., Wang, Z., Xun, Y., Du, L., et al. (2022). First lidar profiling of meteoric Ca+ ion transport from ∼80 to 300 km in the midlatitude nighttime ionosphere. Geophysical Research Letters, 49, e2022GL100537. https://doi.org/10.1029/2022GL100537

[3] Gerrard, A. J., Kane, T. J., Meisel, D. D., Thayer, J. P. & Kerr, R. B. (1997) Investigation of a resonance lidar for measurement of thermospheric metastable helium. J. Atmos. Sol. Terrestrial Phys. 59, 2023–2035

[4] Kaifler, B., Geach, C., Büdenbender, H.C. et al. (2022) Measurements of metastable helium in Earth’s atmosphere by resonance lidar. Nat Commun 13, 6042 https://doi.org/10.1038/s41467-022-33751-6 

How to cite: Geach, C., Kaifler, B., Büdenbender, H. C., Mezger, A., and Rapp, M.: Development of a Helium Resonance Lidar for the Upper Thermosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2156, https://doi.org/10.5194/egusphere-egu23-2156, 2023.

EGU23-3051 | Posters on site | ST3.6

A case study on multiple self-interactions of MSTID bands: New insights 

Sumanta Sarkhel, Dipjyoti Patgiri, Rahul Rathi, Virendra Yadav, Dibyendu Chakrabarty, Subarna Mondal, Mallepulla Venkata Sunil Krishna, Arun K. Upadhayaya, Chiranjeevi G. Vivek, Suresh Kannaujiya, and Surendra Sunda

In this study, we report a special event of nighttime southwestward propagating medium scale traveling ionospheric disturbances (MSTIDs) observed in O(1D) 630.0 nm airglow images from an all-sky imager at Hanle (32.7°N, 78.9°E; Mlat. ~24.1°N), Ladakh, India on a geomagnetically quiet (Ap = 7) night of 15 September 2018. The time sequence of airglow images unveiled two dynamic interactions between multiple dark bands of MSTID. Following the first interaction, one of the interacting bands decayed possibly due to the entrance of plasma from the ambient higher plasma density region. Shortly after this interaction, the other interacting dark band was involved in the second interaction with a third dark band which resulted in the co-alignment of the two interacting bands. Following this co-alignment, one of the bands started rotating prominently that led to further separation of these two co-aligned bands. These changes in the MSTID phase fronts (bands) are explained based on the development of the polarization electric fields arising out of the interactions. This investigation combines the all-sky 630.0 nm airglow imaging observations with TEC maps constructed, for the first time over the Indian sector, from 67 Global Navigation Satellite System (GNSS) measurements to capture the MSTID over this region. The investigation reveals a few important features of self-interactions of MSTID bands over the geomagnetic low-mid latitude transition region which is important to assess their impact over low latitudes. The highlights of these results will be discussed in the meeting.

How to cite: Sarkhel, S., Patgiri, D., Rathi, R., Yadav, V., Chakrabarty, D., Mondal, S., Sunil Krishna, M. V., K. Upadhayaya, A., G. Vivek, C., Kannaujiya, S., and Sunda, S.: A case study on multiple self-interactions of MSTID bands: New insights, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3051, https://doi.org/10.5194/egusphere-egu23-3051, 2023.

EGU23-5387 | ECS | Posters on site | ST3.6

Reconstruction of precipitated electron fluxes using auroral data 

Elisa Robert, Mathieu Barthelemy, Gael Cessateur, Angélique Woelffle, Hervé Lamy, Simon Bouriat, Magnar Gullikstad Johnsen, Urban Brändstörm, and Lionel Biree

Precipitations of auroral electrons characterize the relationship of the magnetosphere and the upper atmosphere, therefore state of near-Earth space depending on their localization and their intensity. One of the main gaps in both data and modelling is the monitoring of the precipitation of low-energy (0.02 – 35 keV) particles in the ionosphere. These particles are responsible of the surface charging on satellites, which lead to trigger electrostatic discharge (ESD) on components. This impact is the most recurrent in space and need to better understand. The method present here, allows an alternative to particle detectors that do not have access to this area.

From optical data, it can be very interesting to reconstruct low energy electron flux in the aurora region. Therefore, the interpretation of the auroral intensities is made using the Transsolo code, a kinetic code which use as input the electron flux and the solar EUV flux on the dayside. It calculates the transport of the suprathermal electrons along a line of sight or a vertical and the subsequent auroral emissions. A optimization method is worked to trying to retrieve electron flux from optical measurements.

The study present here is based on ALIS network data which provides very useful data (Brandstorm, 2003). Tomographic data of the volume emission rate are built from ALIS measurements (Gustavsson, 2000). From tomographic data and transsolo simulations, we adapt the optimization method to reconstruct energetic particles flux. We focus on measurements of the event of 05 March 2008 at 18:41:30 UT and 18:42:40 UT acquired by 5 stations and centred above Skibotn city. Results are presented in the form of maps of mean energy and total energy (corresponding to the energy flux) depending on geographic coordinates. 

How to cite: Robert, E., Barthelemy, M., Cessateur, G., Woelffle, A., Lamy, H., Bouriat, S., Johnsen, M. G., Brändstörm, U., and Biree, L.: Reconstruction of precipitated electron fluxes using auroral data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5387, https://doi.org/10.5194/egusphere-egu23-5387, 2023.

EGU23-6622 | ECS | Posters on site | ST3.6

Impact of individual meteors on the midlatitude ionosphere during the Leonids and Geminids meteor showers, 2019 

Veronika Barta, Csilla Szárnya, Daniel Kouba, Petra Koucka Knizova, Katerina Podolska, Antal Igaz, and Zbysek Mosna

The impact of individual meteors on the lower ionosphere (90-150 km height) has been investigated during wintertime meteor showers using measurements of two DPS-4D Digisondes installed at Sopron (47.63°, 16.72°) and at Pruhonice (50°, 14.5°). The optical measurements of meteors have been performed by a zenith camera installed next to the digisonde at Sopron. It provided the opportunity to compare high cadence ionograms measured during meteor showers parallel with the optical data to determine the plasma trails of individual meteors. Campaign measurements with two ionograms/minute have been performed at Sopron station during the Leonid (16-18 November) and Geminid (10-15 December) meteor showers in 2019. Furthermore, skymaps (1/min) detected by the Digisonde at Sopron during the campaign were also investigated.

In the 20-25% of the observed meteors faint, short-lived (20-120 sec) Es layers were detected on the ionograms during and after (< 2 min) the optical record, which are typical signal of individual meteor trails on the ionogram based on previous studies. There was no observed Es activity at the same height on the ionograms detected before and after these events. Furthermore, the direction of the echo can be also defined on the ionograms of the DPS-4D Digisonde thanks to the multi-beam observation technique. The direction of the detected Es layers agreed well with the optical observations in most of the cases. The maximum frequency of the observed faint layers (foEs) varied between 1,6 and 4,5 MHz, while their height was between 85 and 136 km. Points on the skymaps were also detected at the time of the faint Es layers in 40 % of the cases. The height and direction of the observed points agreed with these parameters of the plasma traces on the ionograms.

Comparing the ionograms with the closest ionosonde observation at Pruhonice station at the same time, we could conclude that the detected faint Es layers were local plasma irregularities, no Es activity at the same height was observed there. This strengthens the hypothesis that the observed trails on the ionograms represents the echo of the optically recorded meteors.

 

How to cite: Barta, V., Szárnya, C., Kouba, D., Koucka Knizova, P., Podolska, K., Igaz, A., and Mosna, Z.: Impact of individual meteors on the midlatitude ionosphere during the Leonids and Geminids meteor showers, 2019, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6622, https://doi.org/10.5194/egusphere-egu23-6622, 2023.

EGU23-7029 | ECS | Orals | ST3.6

Investigation of the Physical Processes Involved in GNSS Amplitude Scintillations at High Latitude: A Case Study 

Giulia D'Angelo, Mirko Piersanti, Alessio Pignalberi, Igino Coco, Paola De Michelis, Roberta Tozzi, Michael Pezzopane, Lucilla Alfonsi, Pierre Cilliers, and Pietro Ubertini

The storm onset on 7 September 2017, triggered several variations in the ionospheric electron density, causing severe phase fluctuations at polar latitudes in both hemispheres. In addition, although quite rare at high latitudes, clear amplitude scintillations were recorded by two Global Navigation Satellite System receivers during the main phase of the storm. This work attempted to investigate the physical mechanisms triggering the observed amplitude scintillations, with the aim of identifying the conditions favouring such events. We investigated the ionospheric background and other conditions that prevailed when the irregularities formed and moved, following a multi-observations approach. Specifically, we combined information from scintillation parameters and recorded by multi-constellation (GPS, GLONASS and Galileo) receivers located at Concordia station (75.10°S, 123.35°E) and SANAE IV base (71.67°S, 2.84°W), with measurements acquired by the Special Sensor Ultraviolet Spectrographic Imager on board the Defense Meteorological Satellite Program satellites, the Super Dual Auroral Radar Network, the Swarm constellation and ground-based magnetometers. Besides confirming the high degree of complexity of the ionospheric dynamics, our multi-instrument observation identified the physical conditions that likely favour the occurrence of amplitude scintillations at high latitudes. Results suggest that the necessary conditions for the observation of this type of scintillation in high-latitude regions are high levels of ionization and a strong variability of plasma dynamics. Both of these conditions are typically featured during high solar activity.

How to cite: D'Angelo, G., Piersanti, M., Pignalberi, A., Coco, I., De Michelis, P., Tozzi, R., Pezzopane, M., Alfonsi, L., Cilliers, P., and Ubertini, P.: Investigation of the Physical Processes Involved in GNSS Amplitude Scintillations at High Latitude: A Case Study, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7029, https://doi.org/10.5194/egusphere-egu23-7029, 2023.

BRAMS (Belgian RAdio Meteor Stations) is a network using forward scatter of radio waves on ionized meteor trails to study meteoroids. It is made of a dedicated transmitter and of 44 receiving stations located in or near Belgium. The transmitter emits a circularly polarized CW radio wave with no modulation at a frequency of 49.97 MHz and with a power of 130 W. Each receiving station uses a 3-element zenith pointing Yagi antenna. The first stations used analog ICOM-R75 receivers and a PC. Since 2018, new improved stations have been installed using digital RSP2 receivers, a GPSDO and a Raspberry Pi, providing better dynamic, sensitivity and stability. 
Recently, several methods have been developed to reconstruct trajectories from meteor echoes recorded at several BRAMS stations. These methods rely on time delays between meteor echoes, pre-t0 phase measurements, and sometimes information from a radio interferometer, or a combination of all the methods. This has opened the possibility to use the BRAMS network to determine the Mesosphere and Lower Thermosphere (MLT) wind speeds using data coming from a large number of meteor echoes.
In this work, we will present the status of the BRAMS network and discuss how BRAMS data can be used to determine MLT wind speeds.  Using a forward scatter system with a very large number of stations allows to increase the number of detections, to increase the altitudinal coverage, and to relax the homogeneity assumption.  Simulations will be considered to estimate the impact of the meteoroid trajectory reconstruction uncertainties (in particular the uncertainty on altitude of the specular reflection point) on the wind speeds retrieval.  We will discuss which temporal and spatial resolutions of the MLT wind field measurements can be achieved.  We will finally discuss several upcoming upgrades of the network and their potential impact on this work.  

How to cite: Lamy, H. and Balis, J.: Mesosphere and Lower Thermosphere wind speed determination using data from the radio forward scatter BRAMS network, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7032, https://doi.org/10.5194/egusphere-egu23-7032, 2023.

EGU23-7183 | Orals | ST3.6 | Highlight

EISCAT and EISCAT_3D 

Axel Steuwer, Anders Tjulin, Ingemar Haggstrom, and Maria Mihalikova

EISCAT Scientific Association is an international non-profit scientific organisation that operates radar infrastructure in Northern Europe to enable research on the ionosphere and the upper atmosphere. Our radars are all located above the Arctic Circle and all radar sites can work together, which provides scientists a unique opportunity to study e.g. the Aurora, Space Weather as well as being able to track Space Debris.

EISCAT is currently constructing the next generation incoherent scatter radar system called EISCAT_3D. This system, EISCAT_3D, is based on phased-array radar technology which allows rapid electronic steering of the beam and thus fast volumetric scanning. In this presentation, we will give an overview of the status of EISCAT and EISCAT_3D, and outline the opportunities ahead. 

How to cite: Steuwer, A., Tjulin, A., Haggstrom, I., and Mihalikova, M.: EISCAT and EISCAT_3D, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7183, https://doi.org/10.5194/egusphere-egu23-7183, 2023.

EGU23-7835 | ECS | Posters on site | ST3.6

Extraction of solar forcing signatures in ground magnetometer data from sub-auroral regions 

Veronika Haberle, Aurélie Marchaudon, Aude Chambodut, and Pierre-Louis Blelly

In order to monitor space weather events and their impacts, ground magnetic field data has proven to be a long-lasting and powerful source of information. For the determination of the impact of solar events it is essential to extract their signatures from the magnetic field signal. However, as the geomagnetic field is a superposition of sources that cover a broad amplitude and frequency spectrum, it is not trivial to isolate storm signatures. The major source is the intrinsically produced magnetic field that changes within years and is called the secular variation. In sub-auroral regions, it is well known that during times of minimum solar forcing the solar quiet current system induces smooth daily variations with strong dependency on season and local time.
In this work we apply signal filtering techniques on time-series magnetic data from ground observatories in sub-auroral regions to extract the various sources. We then use these filter outputs to inspect their dependency and sensitivity to solar forcing. Additionally, statistical parameters are sought after to determine storm signatures.

How to cite: Haberle, V., Marchaudon, A., Chambodut, A., and Blelly, P.-L.: Extraction of solar forcing signatures in ground magnetometer data from sub-auroral regions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7835, https://doi.org/10.5194/egusphere-egu23-7835, 2023.

EGU23-8758 | ECS | Orals | ST3.6

Utilizing optical flow technique to understand plasma convection 

Bea Gallardo-Lacourt, Lindsay Goodwin, D. Megan Gillies, Larry Kepko, Emma Spanswick, Pablo Reyes, and Eric Donovan

Plasma convection is a fundamental process of mass and energy transport within our solar system. In Earth’s magnetosphere, convection models often underestimate, or even fail to identify the contributions of dynamic ionospheric mesoscale (10s-100s km) structures that are responsible for significant energy transfer within the magnetosphere-ionosphere coupled system. The most used convection model relies on data from radars, which operates on spatial scales of approximately 50 km, with a temporal resolution of 2 minutes. In contrast, modern red-line all-sky cameras have a spatial resolution on the order of 1 km and temporal resolution of 3 s. These cameras respond to low energy precipitating electrons, which makes them sensitive tracers of magnetospheric convection, and sensitive to mesoscale structures that may be missed by radars. In recent years, the deployment of new cameras has expanded the coverage to include most of the auroral oval and polar cap above the North American continent. Despite their potential for monitoring and studying ionospheric convection, currently only rudimentary techniques have been applied to measure the motion of these optical structures. In this work, we show initial results of optical flow calculations to analyze the motion of optical structures observed with the new red-line all-sky cameras. Optical flow calculations represent the apparent motion of objects in consecutive frames. The result of this technique provides two-dimensional flow fields, which has enabled us to enhance our understanding of ionospheric electric fields. Finally, perform a validation analysis by comparing the optical flow calculations and incoherent scatter radar measurements.

How to cite: Gallardo-Lacourt, B., Goodwin, L., Gillies, D. M., Kepko, L., Spanswick, E., Reyes, P., and Donovan, E.: Utilizing optical flow technique to understand plasma convection, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8758, https://doi.org/10.5194/egusphere-egu23-8758, 2023.

EGU23-9293 | ECS | Posters on site | ST3.6

HSS/CIR driven storm effects on the ionosphere-thermosphere system 

Gopika Prasannakumara Pillai Geethakumari, Anita Aikio, Lei Cai, Heikki Vanhamaki, Marcus Pedersen, Anthea J. Coster, Aurelie Marchaudon, Pierre-Louis Blelly, Veronika Haberele, Astrid Maute, Nada Ellahouny, Ilkka Virtanen, Johannes Norberg, Shin Oyama, Alexander Kozlovsky, and Maxime Grandin

Solar wind interactions with the Earth’s magnetosphere cause geomagnetic storms and thereby induce ionospheric storms. This study investigates the spatio-temporal evolution of the ionospheric Total Electron Content (TEC) during a moderate but long duration storm driven by solar wind high-speed streams (HSSs) and associated co-rotating interaction region (CIR) during 14-21 March 2016. The storm starts with a strong storm sudden commencement (SSC) with a peak close to 19 UT on 14 March 2016. The GNSS/TEC maps are obtained from the Madrigal database. The associated field-aligned currents (FACs) from AMPERE, ionospheric convection maps from SuperDARN, and the O/N2 ratio from TIMED/GUVI are also studied for understanding the physics behind the different features observed in TEC during the storm.

The study predominantly focuses on the changes of TEC at high and middle latitudes. The storm induced changes in the TEC were extracted by removing the quiet time background (mean of five quietest days of the month) from the TEC maps. During the initial phase, TEC enhancements and depletions are found mainly at high latitudes within the auroral oval and close to the cusp, plausibly associated with auroral precipitation and variations in the upward and downward field-aligned currents (FACs). After the onset of the main phase, the TEC is enhanced at mid-latitudes and auroral ovals with a maximum of ~10 TECU. Meanwhile, a significant decrease in TEC is observed in the polar cap region. During the main phase, we observe the evolution of a storm-enhanced-density (SED) plume and a transient enhancement of TEC in the polar cap. Later during the storm, a strong TEC depletion at high and middle latitudes is found on the dayside and in the evening sector. The depletion of O/N2 ratio, triggered by Joule heating and atmospheric upwelling, could be a plausible reason for the TEC depletion. The possible physical mechanisms associated with the observed TEC variations will be discussed. 

How to cite: Prasannakumara Pillai Geethakumari, G., Aikio, A., Cai, L., Vanhamaki, H., Pedersen, M., J. Coster, A., Marchaudon, A., Blelly, P.-L., Haberele, V., Maute, A., Ellahouny, N., Virtanen, I., Norberg, J., Oyama, S., Kozlovsky, A., and Grandin, M.: HSS/CIR driven storm effects on the ionosphere-thermosphere system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9293, https://doi.org/10.5194/egusphere-egu23-9293, 2023.

EGU23-9724 | ECS | Orals | ST3.6

A new algorithm to separate meteor trail echoes from ionospheric radar scatter 

Magnus Ivarsen, Glenn Hussey, Jean-Pierre St-Maurice, Adam Lozinsky, Draven Galeschuk, Brian Pitzel, and Kathryn McWilliams

Coherent scatter echoes from meteors entering Earth’s atmosphere and those from the ionospheric E-region overlap: echoes of both types are seen at altitudes between 95 km -105 km. The physical origin of plasma irregularities produced by disintegrating meteors naturally differ from that of ionospheric turbulence, and there is a need to distinguish between the two types of echoes. We present a novel algorithm to automatically sort through arbitrarily large datasets of radar echoes with accurate location data, classifying each echo as either meteoric or ionospheric in origin. The algorithm establishes a definition of clustering, in both time and space. We use data from ICEBEAR 3D, an experimental coherent scatter radar in Saskatchewan, Canada. We discuss the two classes of scatter echoes, and present statistical results from 2020, 2021. In future experiments, our proposed algorithm can be applied to both coherent and incoherent radar scatter, provided they come with 3D location information.

How to cite: Ivarsen, M., Hussey, G., St-Maurice, J.-P., Lozinsky, A., Galeschuk, D., Pitzel, B., and McWilliams, K.: A new algorithm to separate meteor trail echoes from ionospheric radar scatter, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9724, https://doi.org/10.5194/egusphere-egu23-9724, 2023.

EGU23-9788 | Posters on site | ST3.6

Neutral Hydrogen in the Terrestrial Thermosphere and Exosphere: Ground-Based Observations 

Edwin Mierkiewicz, Brandon Myers, Susan Nossal, and L. Matthew Haffner

The exosphere is the interface between the Earth's neutral atmosphere and interplanetary space. Our understanding of this important interface, through observations of its mean state and its response to external forcing, will provide important constraints as we seek to develop a complete picture of our complicated space-atmosphere system. This talk will highlight the application of ground-based, high-throughput interference spectroscopy to the study of this important interface. Observations are made throughout the night; the base of the Earth's shadow is used as a first-order probe of the exosphere's altitude structure. Major areas of scientific focus include: (1) high resolution observations of the geocoronal hydrogen Balmer α line profile and its relation to excitation mechanisms, effective temperature, and exospheric physics; (2) retrieval of geocoronal hydrogen parameters such as the hydrogen column abundance [H], the hydrogen density profile H(z), and the photochemically initiated hydrogen flux φ(H); and (3) observations of the geocoronal hydrogen column emission intensity for the investigation of natural variability. Recent work from two unique spectrometers located in Wisconsin and Chile will be reported, with results highlighting each of these three areas of focus. Special emphasis will be placed on high spectral resolution line profile observations of the Balmer α emission line and the forward-model analysis of these data using the lyao_rt radiative transport code of Bishop [1999]. For example, an observed decrease in effective temperature with increasing shadow altitude is found to be a persistent feature for nights in which a wide range of shadow altitudes are sampled. This result will be interpreted in the context of the lyao_rt code. This work is supported by National Science Foundation award AGS-2050077. 

How to cite: Mierkiewicz, E., Myers, B., Nossal, S., and Haffner, L. M.: Neutral Hydrogen in the Terrestrial Thermosphere and Exosphere: Ground-Based Observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9788, https://doi.org/10.5194/egusphere-egu23-9788, 2023.

EGU23-9958 | ECS | Orals | ST3.6

Modelling the Response of Riometers to Medium Energy Electron Precipitation 

Reihaneh Ghaffari, Christopher Cully, Robert Gillies, Emma Spanswick, and Daniel Marsh

Precipitating energetic particles can penetrate into the low-altitude ionosphere and alter the ionization rate. Enhanced ionization in the D-region caused by energetic particle precipitation (EPP) affects cosmic radio signal absorption in the ionosphere. This impact is monitored by a Canadian network of wide-beam passive radio receivers, or riometers, to study precipitation-induced variations in the D-region ionosphere remotely. 

In this study, we examine the relationship between the background ionospheric profiles and absorption during a precipitation event observed by one of the POES satellites in conjunction with the Gillam riometer station (56N, 95W). We use different chemistry models to model the D-region ionosphere and investigate the effect of changing the chemistry model in an absorption event. We compare modelled absorption with ground-based measurements to discuss possible reasons for any discrepancy.

How to cite: Ghaffari, R., Cully, C., Gillies, R., Spanswick, E., and Marsh, D.: Modelling the Response of Riometers to Medium Energy Electron Precipitation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9958, https://doi.org/10.5194/egusphere-egu23-9958, 2023.

EGU23-10103 | Posters on site | ST3.6

The highly advanced ICEBEAR-3D E-region coherent imaging radar 

Glenn Hussey, Adam Lozinsky, Brian Pitzel, Magnus Ivarsen, Draven Galsechuk, Devin Huyghebaert, Kathryn McWilliams, and Jean-Pierre St. Maurice

ICEBEAR (Ionospheric Continuous-wave E-region Bistatic Experimental Auroral Radar) employs advanced software defined radio (SDR) and aperture synthesis radar imaging to produce unambiguous high resolution (1--2~km) 3-dimensional (range, azimuth, elevation) coherent E-region observations.  ICEBEAR-3D operates in the VHF at 49.5~MHz observing the auroral zone of the ionosphere from western Canada (58N, 106W geographic).  The receiver antenna array was re-configuration in 2019 to a non-uniform co-planar T-shaped double interferometer layout to complete the ICEBEAR design and allow for unambiguous, highly detailed, high-resolution coherent radar E-region observations.  We present the antenna array re-configuration; the novel and advanced synthesis aperture radar imaging technique; a low elevation angle accuracy and reliability solution; validations and calibrations of ICEBEAR-3D using celestial radio sources (Cygnus A) and interferometer closure angles; as well as some initial E-region and meteor trail observations and analysis.

How to cite: Hussey, G., Lozinsky, A., Pitzel, B., Ivarsen, M., Galsechuk, D., Huyghebaert, D., McWilliams, K., and St. Maurice, J.-P.: The highly advanced ICEBEAR-3D E-region coherent imaging radar, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10103, https://doi.org/10.5194/egusphere-egu23-10103, 2023.

EGU23-11994 | ECS | Posters on site | ST3.6

The response of field-aligned and horizontal ionospheric currents to HSS/SIR driven storms and comparison to ICME driven storms 

Marcus Pedersen, Heikki Vanhamäki, and Anita Aikio

The time delay from an interplanetary driver arriving at the magnetopause to the response in the ionospheric and field-aligned currents (FAC) has never been quantified separately for different types of storm drivers. The development and evolution of the total FAC during storms driven by high speed streams and associated stream interaction regions (HSS/SIR) are different compared to these driven by the sheath and magnetic clouds of interplanetary coronal mass ejections (ICME), as shown in Pedersen et al. (2021, 2022). The main differences are that the FACs in HSS/SIR storms maximize earlier in the storm main phase and are less intense than during ICME storms. Likewise, differences in response times is possible. The delay time for HSS/SIR driven storms is investigated using cross correlation analysis between the total FAC and SME index and the Newell coupling function (NCF), and is compared to sheath and MC driven storms. It is found that the total FAC and SME index lag the NCF by 40 ± 10 min during storms driven by HSS/SIR and sheaths, and by 60 ± 10 min for MCs. Additionally, the total FAC best correlate with the NCF when using solar wind data averaged over the preceding 60 min for sheath, 100 min for HSS/SIR and 120 min for MC driven storms.

How to cite: Pedersen, M., Vanhamäki, H., and Aikio, A.: The response of field-aligned and horizontal ionospheric currents to HSS/SIR driven storms and comparison to ICME driven storms, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11994, https://doi.org/10.5194/egusphere-egu23-11994, 2023.

EGU23-12698 | ECS | Orals | ST3.6 | Highlight

Study of D region ionosphere using incoherent scatter radar measurements 

Neethal Thomas, Antti Kero, and Ilkka Virtanen

Within the recently started "HPC-approach to Ionospheric Situational Awareness (HISSA)" project, we will re-analyze a comprehensive set of existing European incoherent scatter radar (EISCAT) measurements from Tromso VHF radar carried out since 1990. Our special focus is to extract, for the first time, the spectral information of these experiments for the benefit of better understanding the potential long-term changes in the polar D-region ionosphere. Backscattered spectral parameters are estimated by fitting a theoretical autocorrelation function (ACF) to the observed data by using a Markov chain Monte Carlo (MCMC) inversion approach. The methodology and some preliminary results of the neutral temperature, electron density, and plasma drift velocity at D region altitudes will be presented. The temperature estimates from EISCAT VHF measurements are compared with the simultaneous LIDAR temperature measurements from Tromso. The challenges of D-region temperature estimates from incoherent scatter radar spectral parameters, which is a function of ion-to-neutral collision frequency and ion mass will be discussed in detail.

How to cite: Thomas, N., Kero, A., and Virtanen, I.: Study of D region ionosphere using incoherent scatter radar measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12698, https://doi.org/10.5194/egusphere-egu23-12698, 2023.

EGU23-12835 | Orals | ST3.6

PLIP: An imaging Polarimeter for the Auroral line Emissions 

Gaël Cessateur, Herve Lamy, Léo Bosse, Mathieu Barthelemy, Jean Lilensten, Magnar G. Johnsen, Frederique Auriol, Maxime Catalfamo, and Olivier Pujol

The measurements of the polarization of auroral emission lines in the Earth’s atmosphere is of particular interest for the understanding of the upper atmosphere but also for potential space weather applications. Emissions from the oxygen red line at 630 nm has been observed polarized since 2008 and the origin of the polarization is likely due to the imbalance of Zeeman sublevels, which comes from the magnetospheric electrons precipitating with a pitch angle distribution more or less aligned with the local magnetic field. The polarization of the blue line at 427.8 nm from N2+, and the green light at 557.7 nm from the atomic oxygen have been also observed but their origin remains unknown. Those observations were carried out using multi-wavelength sensitive photo-polarimeters with a narrow field of view, of about 2°. Here we will present a new instrument, the Polar Lights Imaging Polarimeter (PLIP), using 4 high-resolution monochrome cooled CMOS cameras with very low read-out noise, and a FOV of approximately 44° x 30°. Those cameras are designed for faint deep sky objects, and paired with some 24mm lenses opened at F/2.8. We added up some linear polarization filters oriented at 0°, 45°, 90° and 135° to infer the DoLP and AoLP. Filter wheels have been added with narrow interference filters (with a FWHM of about 3 nm) centered on the blue (427.8 nm), green (557.7 nm) and red (630.0 nm) emission lines. Since the polarization can also be induced from Mie and Rayleigh scattering of the light pollution from nearby sources, a radiative transfer code POMEROL is used to infer the polarization from the auroral spectral lines only. Some preliminary results will be presented from an observation campaign in Norway perfomed in November 2022 and January 2023.

 

How to cite: Cessateur, G., Lamy, H., Bosse, L., Barthelemy, M., Lilensten, J., Johnsen, M. G., Auriol, F., Catalfamo, M., and Pujol, O.: PLIP: An imaging Polarimeter for the Auroral line Emissions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12835, https://doi.org/10.5194/egusphere-egu23-12835, 2023.

EGU23-13647 | Posters on site | ST3.6

Quasi exhaustive synthetic spectra of the aurora and spectrometers measurements 

Mathieu Barthelemy, Elisa Robert, and Thierry Sequies

Studying the auroral emission is of strong importance since they are created in an atmospheric layer (80-300 km) where in situ measurements are complicated. They represent a good proxy of the particle precipitations into atmosphere.

The spectrum of the aurora is complex made of both atomic and molecular lines. The intensities of these emissions vary with the activity, especially the particle precipitations.

Transsolo is the kinetic code which solve the transport equation of the electrons along a vertical or a magnetic field line. It allows to obtain the particles fluxes at different energies, angles and altitudes. From this, the code is able to calculate the related emissions.

The emission modules have recently been updated by including the vibrational structures of the molecular bands. Several atomic lines have also been added. We can consider that we include more than 95% of the full emission spectra. From this, it is now possible to obtain some almost complete synthetic spectra of the aurora parametrized by the mean energy of the particle fluxes at the top of the atmosphere and the total precipitated energy.

Recently Robert et al. show that it is possible to reconstruct the energetic precipitation from the N2+ 427 nm line. However, it remains clear that multiplying the number of considered lines, will allow to get more accurate measurements of these particle fluxes. Moreover, a large number of auroral monitoring instruments are done with filters with variable widths. Such synthetic spectra can help to identify the possible perturbation of the measurements due to wavelength coincidences. For example, the green line at 557 nm is in coincidence with several O2+ and N2 bands in a +/- 5 nm range. Calculating the relative ratio of these lines in different conditions is then crucial.

In parallel, we are developing a series of calibrated high sensitivity spectrometers to validate the data and enhance the quality of particle precipitation reconstructions.

In this presentation, we will detail the links between these instruments and these synthetic spectra.

How to cite: Barthelemy, M., Robert, E., and Sequies, T.: Quasi exhaustive synthetic spectra of the aurora and spectrometers measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13647, https://doi.org/10.5194/egusphere-egu23-13647, 2023.

EGU23-14173 | Posters on site | ST3.6

E3D-BRITE: EISCAT_3D-based reconstruction of ionosphere-thermosphere electrodynamics 

Spencer Mark Hatch, Jone Peter Reistad, Karl Magnus Laundal, Ilkka Virtanen, Heikki Vanhamäki, Matthew Zettergren, and Kjellmar Oksavik

In many experimental studies of ionosphere-thermosphere (IT) coupling and ionospheric electrodynamics, the limitations of existing observational data sets require one to represent the three-dimensional IT system as an infinitely thin, two-dimensional sheet. This 2D representation of the coupled IT system cannot however represent some of its most basic properties, such as the existence of different ionospheric layers. On the other hand, observing systems that are capable of probing the altitudinal structure of relevant quantities, such as plasma density and drift, often can only provide information within a very narrow overhead volume. This limitation typically requires one to assume that these quantities have no horizontal gradients. Measurements from the upcoming EISCAT_3D incoherent scatter radar therefore present an unprecedented opportunity to probe the 3D IT system in three dimensions and on relatively short time scales (of order minutes). Here we present a data assimilation technique, EISCAT_3D-based reconstruction of ionosphere-thermosphere electrodynamics (E3D-BRITE), for routine estimation of all three components of the ionospheric current density and their uncertainties. We illustrate the technique using synthetic EISCAT_3D measurements of the plasma density and ion drift. We describe how the E3D-BRITE technique can also be used to simultaneously estimate the neutral wind and the perpendicular electric field. The technique relies on a 3D generalization of curl-free and divergence-free Cartesian elementary current systems. We also discuss the limitations imposed on this technique by the geometry of the three EISCAT_3D sites in Skibotn, Karesuvanto, and Kaiseniemi.

How to cite: Hatch, S. M., Reistad, J. P., Laundal, K. M., Virtanen, I., Vanhamäki, H., Zettergren, M., and Oksavik, K.: E3D-BRITE: EISCAT_3D-based reconstruction of ionosphere-thermosphere electrodynamics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14173, https://doi.org/10.5194/egusphere-egu23-14173, 2023.

EGU23-14830 | ECS | Posters on site | ST3.6

Data reduction of plasma lines in Incoherent Scatter Radar spectrum 

Mini Gupta, Patrick Guio, and Juha Vierinen

In the ionosphere, a sustained population of suprathermal electrons is generated due to photoionization or electron precipitation. At resonance, the phase velocity of the electrons matches the Langmuir phase velocity observed by the Incoherent Scatter Radar (ISR). As a result, the scattered power in the plasma line spectrum is enhanced, thus making it possible to detect them. Plasma lines can be used to improve the accuracy of the estimates of electron density and temperature, study features in the electron velocity distribution of the suprathermal electrons and provide an independent method to calculate ionospheric currents.  

We analyzed the data collected with the EISCAT Tromsø UHF radar on 27 January 2022. We present a novel technique of data reduction to detect plasma lines and extract parameters. We use the method developed by Ivchenko (2017) to determine the times with enhanced plasma lines. For those times, we model the spectrum with a Gaussian function, where the plasma line intensity, frequency and bandwidth correspond to the amplitude, mean and variance, respectively. We observe photoelectron-enhanced plasma lines between 09:16:15 LT – 13:56:15 LT. All the detected plasma lines are field-aligned, except for 11:29:30 LT - 12:51:30 LT, when they are also detected in the vertical direction (i.e. at 11.67° to the magnetic field). The detection of the plasma lines is accompanied by an increase in the electron density estimates from the ion line. 

How to cite: Gupta, M., Guio, P., and Vierinen, J.: Data reduction of plasma lines in Incoherent Scatter Radar spectrum, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14830, https://doi.org/10.5194/egusphere-egu23-14830, 2023.

EGU23-15004 | ECS | Posters on site | ST3.6

First evidence of polarized emissions in pulsating aurorae 

Leo Bosse, Gaël Cessateur, Hervé Lamy, Jean Lilensten, Nicolas Gillet, Colette Brogniez, Olivier Pujol, Sylvain Rochat, Stéphane Curaba, Alain Delboulbé, and Magnar G. Johnsen

In the last decade, several instruments have been developped to measure the auroral light polarisation. However, its study has faced the issue of anthropic light pollution and scattering in the lower atmosphere (Bosse et al., 2020). To overcome this challenge, several methods were used, and until now, the most succesfull was the use of a polarised radiative transfer model (Bosse et al., 2022) to identify the light pollution contribution. However during the past year a new look at the data revealed that pulsating aurorae are polarised, and that this polarisation carries a lot of information. The main advantage of using pulsating aurorae is that the variations in the light polarisation are very fast, of the order of a few seconds. This allows us to dismiss any potential source of polarisation that are not synched with the pulsation of the aurora.

These polarisation patterns are seen in the green atomic oxygen line at 557.7 nm, the 1st N2+ negative band at 391.4 nm (purple) and 427.8 nm (blue).

There are no clear explanations on the origin of this auroral polarisation, or its relation to the local state of the upper atmosphere. An hypothesis is that this polarisation can be either created directly at the radiative de-excitation or may occur when the non-polarised emission crosses the ionospheric currents.

We will present how these new findings confirm the ionospheric origin of the polarisation observed from the ground, as well as some of the potentialities these observations and models offer in the frame of space weather, aerosol and light pollution study.

How to cite: Bosse, L., Cessateur, G., Lamy, H., Lilensten, J., Gillet, N., Brogniez, C., Pujol, O., Rochat, S., Curaba, S., Delboulbé, A., and Johnsen, M. G.: First evidence of polarized emissions in pulsating aurorae, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15004, https://doi.org/10.5194/egusphere-egu23-15004, 2023.

EGU23-15257 | Orals | ST3.6

The height of green 557.7 nm and blue 427.8 nm aurora 

Daniel Whiter, Noora Partamies, Björn Gustavsson, and Kirsti Kauristie

An estimate of the height of the aurora is often required for the derivation or interpretation of other auroral or ionospheric parameters, such as horizontal spatial scales, velocities, neutral temperatures, or electron precipitation energies. We have performed a large statistical study of the peak emission height of coincident green 557.7 nm and blue 427.8 nm aurora using a network of ground-based all-sky cameras stationed in northern Finland and Sweden. We have obtained almost 58000 simultaneous measurements of both emissions between 2000 and 2007, and found that both emissions typically peak at about 114 km, but the distribution of peak emission heights is more skewed for blue aurora than for green aurora.

During low-energy electron precipitation (< 4 keV), when the two emissions peak above about 110 km, it is more likely for the blue emission to peak above the green emission than vice-versa. Modelling has shown that this is because the dominant mechanism producing the O(1S) upper state of the green line is energy transfer from N2. The rate of that process depends on the product of the N2 and O number densities, which both decrease to higher altitude. The blue line is produced through electron impact ionisation of N2, and so depends on the N2 number density only, and consequently peaks below the green emission.

During high-energy electron precipitation the two emissions typically peak at very similar altitude. In those circumstances, where the emissions peak below the peak in O number density, energy transfer from N2 must not be the dominant production mechanism of O(1S). Dissociative recombination of O2+ seems most likely to be the dominant mechanism, but modelling cannot fully reproduce observations and there may be an additional mechanism which is currently unaccounted for.

The observations are best reproduced using a Maxwellian shaped electron precipitation spectrum at low energies, but a Gaussian shaped electron precipitation spectrum at high energies.

How to cite: Whiter, D., Partamies, N., Gustavsson, B., and Kauristie, K.: The height of green 557.7 nm and blue 427.8 nm aurora, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15257, https://doi.org/10.5194/egusphere-egu23-15257, 2023.

EGU23-16488 | Posters on site | ST3.6

Space Weather Effects On Plasmasphere, Ionosphere and Thermosphere Systems during November 2021 Geomagnetic Storm, as probed in the Northern Hemisphere 

Mauro Regi, Loredana Perrone, Alfredo Del Corpo, Luca Spogli, Dario Sabbagh, Claudio Cesaroni, Laura Alfonsi, Paolo Bagiacchi, Lili Cafarella, Giuseppina Carnevale, Marcello De Lauretis, Domenico Di Mauro, Pierluigi Di Pietro, Patrizia Francia, Balázs Heilig, Stefania Lepidi, Carlo Marcocci, Fabrizio Masci, Adriano Nardi, and Alessandro Piscini and the Mauro Regi

On 4 November 2021 it was detected the most intense geomagnetic storm that occurred so far during the rising phase of solar cycle 25 (Kp=8-). This work summarizes the state of the solar wind before and during the geomagnetic storm, the response of the plasmasphere-ionosphere-thermosphere system in the European sector and, for a comparison, the ionosphere-thermosphere response of the American sector. The plasmasphere dynamics was investigated through field line resonances detected at the European quasi-Meridional Magnetometer Array. The ionosphere was investigated through the combined use of ionospheric parameters (foF2, hmF2) from ionosondes and Total Electron Content (TEC) obtained from Global Navigation Satellite System receivers at four locations in the European sector and three locations in the American sectors. Aeronomic parameters were retrieved by using an original method based on the observed electron concentration in the ionospheric F region. The behavior of foF2 and TEC data is also discussed, speculating about the possible interconnection between the topside ionosphere and the plasmasphere at the investigated European sites. Experimental results can be summarized as it follows: a) The plasmasphere, originally in a state of saturation, was eroded up to two Earth’s radii, and only partially recovered after the main phase of the storm, and a possible formation of a drainage plume is also observed; b) The ionospheric parameters showed phases characterized by negative and positive variations, with longitudinal and latitudinal dependence of storm features in the European sector; c) Negative storm signature in electron concentration at the F2 region is also observed in the American sector. This result is mainly attributable to the neutral composition and temperature variations.

How to cite: Regi, M., Perrone, L., Del Corpo, A., Spogli, L., Sabbagh, D., Cesaroni, C., Alfonsi, L., Bagiacchi, P., Cafarella, L., Carnevale, G., De Lauretis, M., Di Mauro, D., Di Pietro, P., Francia, P., Heilig, B., Lepidi, S., Marcocci, C., Masci, F., Nardi, A., and Piscini, A. and the Mauro Regi: Space Weather Effects On Plasmasphere, Ionosphere and Thermosphere Systems during November 2021 Geomagnetic Storm, as probed in the Northern Hemisphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16488, https://doi.org/10.5194/egusphere-egu23-16488, 2023.

EGU23-17159 | Posters on site | ST3.6

Ground truth validation of the CMIP energetic particle precipitation forcing 

Antti Kero, Neethal Thomas, Ilkka Virtanen, Pekka Verronen, Max van de Kamp, and Hilde Nesse

The forcing component of energetic particle precipitation (EPP) is recently added into the IPCC's official Coupled Model Intercomparison Project (CMIP) climate modelling. According to these simulations, the impact of inclusion of the medium energy electrons to the ozone variability was estimated to be 12-24% in the mesosphere and 5-7% in the stratosphere.
However, to obtain a continuous particle forcing required for these multi-decadal simulations, the precipitating particle flux spectrum was parameterised by the magnetic Ap index to match statistically to the POES satellite's MEPED particle detector data. This rather simple approach has several uncertainties, but the most critical one is that the existing satellite-borne particle detectors, including the MEPED instrument, struggle to separate the loss cone populations from trapped particles, leading to biases in EPP forcing especially in the relativistic energies.
In this presentation, we evaluate various EPP forcing models proposed for the future CMIP climate models against the EISCAT VHF data. This can be regarded as a ground-thruth approach for the mesospheric ionisation essential for the atmospheric consequences of the EPP.

How to cite: Kero, A., Thomas, N., Virtanen, I., Verronen, P., van de Kamp, M., and Nesse, H.: Ground truth validation of the CMIP energetic particle precipitation forcing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17159, https://doi.org/10.5194/egusphere-egu23-17159, 2023.

ST4 – Space Weather and Space Climate

The Space Weather Empirical Ensemble Package (SWEEP) is a 3-year project that, very recently, delivered a suite of software tools to the UK Met Office to improve their space weather forecasting capabilities. Part of this package was Automated CME Characterisation (ACMEC) software to automatically detect, and characterise, CMEs in near real-time (NRT) coronagraph data. ACMEC ingests STEREO COR2 beacon data, and SOHO LASCO C2/C3 NRT data, and given the availability of clean data, provides estimates of the CME’s 3D trajectory, angular extent, and speed. It also provides estimates of uncertainties in these values, enabling an ensemble forecast at Earth. We present example case studies to show the efficiacy of ACMEC, and reflect on the challenges faced, and lessons learned during the development stages. Future perspectives are given, including new missions, and the realisation that the development of machine learning methods are required for such complicated tasks in the next 10 years. 

How to cite: Morgan, H., Bunting, K., Gandhi, H., and Williams, T.: Automated detection and characterision of CMEs in near real-time coronagraph data: lessons and challenges arising from the SWEEP project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1121, https://doi.org/10.5194/egusphere-egu23-1121, 2023.

EGU23-2226 | ECS | Orals | ST4.1

Predicting CMEs Using ELEvoHI With STEREO-HI Beacon Data 

Maike Bauer, Tanja Amerstorfer, Andreas J. Weiss, Jackie A. Davies, Christian Möstl, Ute V. Amerstorfer, Martin A. Reiss, and Richard A. Harrison

Coronal mass ejections (CMEs) are the main drivers of geomagnetic storms at Earth and are capable of impacting power grids on the planet’s surface as well as satellites in orbit. Developing models to accurately predict the arrival time and speed of CMEs is a necessary step towards ensuring that we are capable of providing advance warning to mitigate potential severe space weather effects. We use the Ellipse Evolution model based on Heliospheric Imager observations (ELEvoHl) to predict the arrival of CMEs at Earth using data from STEREO-A’s heliospheric imagers. The HI instruments provide both real-time, lower-quality beacon data as well as higher- quality science data which is downlinked to Earth with some delay. Issuing alerts for approaching CMEs before they arrive at Earth necessitates the utilization of real-time data. HI data for each event and data type is compiled into a time-elongation plot (Jmap) in which every CME’s trajectory is tracked manually. We predict the arrival time and speed of 10 Earth-directed CMEs from 2010 to 2020 using both science and beacon data with the ELEvoHI model and compare the results in terms of accuracy across both data types. We find that predictions made using beacon data are generally worse than those made using science data and give an outlook on possible future perspectives for improving the real-time prediction of CMEs.

How to cite: Bauer, M., Amerstorfer, T., Weiss, A. J., Davies, J. A., Möstl, C., Amerstorfer, U. V., Reiss, M. A., and Harrison, R. A.: Predicting CMEs Using ELEvoHI With STEREO-HI Beacon Data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2226, https://doi.org/10.5194/egusphere-egu23-2226, 2023.

EGU23-2636 | Posters on site | ST4.1

CME real time prediction using HI beacon data confined by a Solar Orbiter arrival 

Tanja Amerstorfer, Maike Bauer, Christian Möstl, Ronan Laker, Timothy S. Horbury, Mateja Dumbovic, Helen O'Brien, Edward J. Fauchon-Jones, Jackie A. Davies, Richard A. Harrison, and David Barnes

On March 7, 2022 at 22:49 UT, a coronal mass ejection impacted Solar Orbiter, located almost exactly on the Sun-Earth line at a heliocentric distance of 0.49 AU. This exceptionally advantageous spacecraft location yielded the opportunity of constraining the ensemble of our CME propagation model, ELEvoHI, in a way that only the most accurate ensemble members at Solar Orbiter (in terms of predicted arrival time) contributed to the prediction for L1. ELEvoHI is based on STEREO's heliospheric imager data that is available in real time only in a reduced quality, i.e. lower spacial and time resolution compared to science data. However, considering the arrival at Solar Orbiter it was possible to precisely predict the arrival of the CME sheath at L1 in real time. These results emphasize the benefit of having (a) spacecraft situated between the Sun and Earth as an early warning system for Earth-directed CMEs.

How to cite: Amerstorfer, T., Bauer, M., Möstl, C., Laker, R., Horbury, T. S., Dumbovic, M., O'Brien, H., Fauchon-Jones, E. J., Davies, J. A., Harrison, R. A., and Barnes, D.: CME real time prediction using HI beacon data confined by a Solar Orbiter arrival, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2636, https://doi.org/10.5194/egusphere-egu23-2636, 2023.

EGU23-4005 | Orals | ST4.1

Physics-informed Machine Learning prediction of ambient solar wind speed 

Enrico Camporeale and Andong Hu

Forecasting the ambient solar wind several days in advance still proves extremely difficult. In fact, state-of-the-art models (either physics-based or based on machine learning) do not consistently outperform simple baseline predictions based on 1-day persistence or 27-day recurrence. In turn, our inability to precisely forecast the ambient solar wind impacts both the accuracy and the lead-time of every Geospace and Magnetosphere-Ionosphere-Thermosphere model used for space weather purposes.

Here, we present preliminary results about a physics-informed machine learning model that aims to predict the ambient solar wind up to 5 days ahead, by combining Global Oscillation Network Group (GONG) observations and a simplified solar wind propagation model, known as HUX (Heliospheric Upwind eXtrapolation). In essence the model learns a coronal model in a completely data-driven fashion, by using ACE observations as its target.

How to cite: Camporeale, E. and Hu, A.: Physics-informed Machine Learning prediction of ambient solar wind speed, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4005, https://doi.org/10.5194/egusphere-egu23-4005, 2023.

EGU23-5512 | Orals | ST4.1

Space Weather Roadmap update for iSWAT Clusters H1+H2 

Manuela Temmer, Camilla Scolini, Ian G. Richardson, Stephan G. Heinemann, Evangelos Paouris, Angelos Vourlidas, and Mario M. Bisi and the iSWAT Cluster H1+H2 Writing teams

The COSPAR iSWAT (international Space Weather Action Teams) initiative is a global hub for collaborations addressing challenges across the field of space weather. We present the COSPAR Space Weather Roadmap update for the iSWAT clusters H1+H2 covering interplanetary space and its characteristics, with focus on large-scale corotating and transient structures impacting Earth. We review the physical background of different solar wind streams together with coronal mass ejections and the considerable efforts that have been made to model these phenomena. We outline the limitations coming from observations with rather large uncertainties, making reliable predictions of the structures impacting Earth difficult. Moreover, in the wake of the upcoming solar cycle 25, the increased complexity of interplanetary space with enhanced solar activity poses a challenge to models. The current paper presents the efforts and progress achieved in recent years, identifies open questions, and gives an outlook for the next 5-10 years.

How to cite: Temmer, M., Scolini, C., Richardson, I. G., Heinemann, S. G., Paouris, E., Vourlidas, A., and Bisi, M. M. and the iSWAT Cluster H1+H2 Writing teams: Space Weather Roadmap update for iSWAT Clusters H1+H2, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5512, https://doi.org/10.5194/egusphere-egu23-5512, 2023.

EGU23-6142 | ECS | Orals | ST4.1

Bottlenecks in space weather model validation: Where do we stand and how do we move forward? 

Martin Reiss, Karin Muglach, Barbara Perri, Richard Mullinix, and Chiu Wiegand

The rate at which we develop and update solar and heliospheric models has outpaced the rate at which we build our data and validation infrastructure. As a consequence, we end up with a bottleneck in advancing heliospheric modeling. The validation practices that rely only on selected events and time intervals, the usage of individually developed metrics, and a slow iterative process between developers and end-users all contribute to this bottleneck. These validation practices make a complete assessment of the "state-of-the-art" in space weather modeling difficult or even impossible. Here we present the activities of the Ambient Solar Wind Validation Team embedded in the COSPAR ISWAT initiative. Our mission is to provide the science community with an assessment of the state-of-the-art in solar wind modeling at Earth and other planetary environments. To this end, we are developing an open online platform hosted at NASA's CCMC for validating large-scale solar wind models by comparing their solutions with measurements from space explorers. The new online platform will allow the space weather community to test the quality of state-of-the-art solar wind models with unified metrics providing an unbiased assessment of progress over time. In this contribution, we will give a status update on our team effort, showcase the first version of the online platform, and outline future perspectives.

How to cite: Reiss, M., Muglach, K., Perri, B., Mullinix, R., and Wiegand, C.: Bottlenecks in space weather model validation: Where do we stand and how do we move forward?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6142, https://doi.org/10.5194/egusphere-egu23-6142, 2023.

EGU23-7764 | Posters on site | ST4.1

Short term forecast of CME flux rope signatures using 3DCORE 

Ute Amerstorfer, Hannah Rüdisser, Andreas Weiss, Christian Möstl, Tanja Amerstorfer, and Maike Bauer

The 3D coronal rope ejection (3DCORE) model has proven to work quite well for fitting 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. For the fitting part an approximate Bayesian computation sequential Monte Carlo algorithm is utilized, which allows us to generate estimates on the uncertainty of model parameters using only a single in situ observation.
In the present study, we test the ability of 3DCORE to perform short term forecasts of an ICME’s magnetic field. Therefore, we use only the first couple of hours of an in situ observation to which 3DCORE fits a magnetic field and predicts the rest of the flux rope structure.

How to cite: Amerstorfer, U., Rüdisser, H., Weiss, A., Möstl, C., Amerstorfer, T., and Bauer, M.: Short term forecast of CME flux rope signatures using 3DCORE, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7764, https://doi.org/10.5194/egusphere-egu23-7764, 2023.

EGU23-8215 | Orals | ST4.1

Space Weather with Uncertainty Quantification: A New Sequence of Data-driven Models of the Solar Atmosphere and Inner Heliosphere 

Nikolai V. Pogorelov, Charles N. Arge, Jon Linker, Lisa Upton, Brian Van Straalen, Ronald Caplan, Phillip Colella, Cooper Downs, Christopher Gebhard, Dinesha Vasanta Hegde, Carl Henney, Shaela Jones-Mecholsky, Tae Kim, Miko Stulajter, Talwinder Singh, James Turtle, and Mehmet Yalim

To address Objective II of the National Space Weather Strategy and Action Plan 'Develop and Disseminate Accurate and Timely Space Weather Characterization and Forecasts' and US Congress PROSWIFT Act 116–181, our team is developing a new set of open-source software that would ensure substantial improvements of Space Weather (SWx) predictions. On the one hand, the focus is on the development of data-driven models. On the other hand, each individual component of our software will have higher accuracy with a dramatically improved performance. This is done by the application of new computational technologies and enhanced data sources. The development of such software paves way for improved SWx predictions accompanied with an appropriate uncertainty quantification. This will make it possible to forecast hazardous SWx effects on the space-borne and ground-based technological systems, and on human health. Our models involve (1) a new, open-source solar magnetic flux model (OFT), which evolves information to the back side of the Sun and its poles, and updates the model flux with new observations using data assimilation methods; (2) a new potential field solver (POT3D) associated with the Wang-Sheeley-Arge coronal model, and (3) a new adaptive, 4-th order of accuracy solver (HelioCubed) for the Reynolds-averaged MHD equations implemented on mapped multiblock grids (cubed spheres). We describe the software and results obtained with it, including the appication of machine learning to modeling coronal mass ejections, which makes it possible to improve SWx predictions by decreasing the time-of-arrival mismatch.  The test show that our software is formally more accurate and performs much faster than its predecessors used for SWx predictions.

How to cite: Pogorelov, N. V., Arge, C. N., Linker, J., Upton, L., Van Straalen, B., Caplan, R., Colella, P., Downs, C., Gebhard, C., Hegde, D. V., Henney, C., Jones-Mecholsky, S., Kim, T., Stulajter, M., Singh, T., Turtle, J., and Yalim, M.: Space Weather with Uncertainty Quantification: A New Sequence of Data-driven Models of the Solar Atmosphere and Inner Heliosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8215, https://doi.org/10.5194/egusphere-egu23-8215, 2023.

EGU23-8877 | ECS | Orals | ST4.1

Understanding our capabilities in observing and modelling Coronal Mass Ejections 

Christine Verbeke, M. Leila Mays, and Marilena Mierla and the International Team 480 from the International Space Science Institute: Understanding Our Capabilities In Observing And Modeling Coronal Mass Ejections

Coronal Mass Ejections (CMEs) are large-scale eruptions of plasma and magnetic fields from the Sun. They are considered to be the main drivers of strong space weather events at Earth. Multiple models have been developed over the past decades to be able to predict the propagation of CMEs and their arrival time at Earth. Such models require input from observations, which can be used to fit the CME to an appropriate structure.

When determining input parameters for CME propagation models, it is common procedure to derive kinematic parameters from remote-sensing data. The resulting parameters can be used as inputs for the CME propagation models to obtain an arrival prediction time of the CME f.e. at Earth. However, when fitting the CME structure to obtain the needed parameters for simulations, different geometric structures and also different parts of the CME structure can be fitted. These aspects, together with the fact that 3D reconstructions strongly depend on the subjectivity and judgement of the scientist performing them, may lead to uncertainties in the fitted parameters. Up to now, no large study has tried to map these uncertainties and to evaluate how they affect the modelling of CMEs. Furthermore, when using these determined parameters as inputs into CME propagation models, they spread throughout the modelling domain and influence the final results of the simulation and the predicted arrival time of the modelled CME.

Fitting a large set of CMEs within a selected period of time, we aim to investigate the uncertainties in the CME fittings in detail. Each event is fitted multiple times by different scientists. We discuss statistics on uncertainties of the fittings. We also present some first results of the impact of these uncertainties on CME propagation modelling.

Acknowledgements: This work has been partly supported by the International Space Science Institute (ISSI) in the framework of International Team 480 entitled: Understanding Our Capabilities In Observing And Modeling Coronal Mass Ejections'.

How to cite: Verbeke, C., Mays, M. L., and Mierla, M. and the International Team 480 from the International Space Science Institute: Understanding Our Capabilities In Observing And Modeling Coronal Mass Ejections: Understanding our capabilities in observing and modelling Coronal Mass Ejections, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8877, https://doi.org/10.5194/egusphere-egu23-8877, 2023.

Our new magnetohydrodynamics (MHD) simulation model of the solar corona and solar wind and its new capabilities are presented. This model covers the range of heliocentric distance from 2.5 solar radii (Rs) up to 1 AU and beyond. Starting the simulation from 2.5 Rs, our Sun-to-Earth MHD model can utilize straightforwardly the information on the coronal mass ejection (CME) and its associated magnetic flux rope at their earliest phase.

This model is constructed by introducing the characteristic-based boundary treatment to our existing H3DMHD model [e.g. Wu+ (2015) JGR 121:1839]. The characteristic-based boundary treatment [e.g. Nakagawa+ (1987) A&Ap 197:354; Wu & Wang (1987) CMAME 64:267] can treat the temporal variations of MHD variables on the sub-sonic/Alfvenic boundary surface in a mathematically and physically consistent manner and enhances the computational robustness. In tailoring a set of characteristic equations for this new model, we assume that the coronal magnetic field is open to the interplanetary space and the solar coronal plasma is flowing outward everywhere at 2.5 Rs. Without the characteristic-based boundary treatment, we often fail to obtain the quasi-steady state of the solar corona and solar wind.

This new model can introduce various types of the numerical perturbation mimicking the CME initiation to the quasi-steady state of the trans-sonic/Alfvenic solar wind. For example, an outward-moving and expanding CME structure can be introduced as the time-dependent boundary values by calculating the MHD variables of the CME structures on the 2.5-Rs intersection. In the present model, the characteristic-based boundary treatment is not used for the boundary grids the CME is passing through, for simplicity; although, it is possible to construct a new set of characteristic equations incorporating with the CME model.

In this presentation, the details of the characteristic-based boundary treatment for the middle of the corona (hence, named CharM) are provided. The results of test simulations with various choices of parameters for the background steady trans-sonic/Alfvenic solar wind and the CME perturbations are compared to assess the dynamics of the CME evolution in the earliest period of the Sun-to-Earth disturbance propagation.

How to cite: Hayashi, K., Wu, C.-C., Liou, K., and Chen, J.: A new time-dependent three-dimensional magnetohydrodynamics (MHD) simulation model for the trans-sonic/Alfvenic solar wind from 2.5Rs, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9206, https://doi.org/10.5194/egusphere-egu23-9206, 2023.

EGU23-9811 | Orals | ST4.1

An Efficient, Time-Dependent High Speed Stream Model and Application to Solar Wind Forecasts 

Christina Kay, Teresa Nieves-Chinchilla, Stefan Hofmeiseter, and Erika Palmerio

Predicting space weather effects of the solar wind requires knowing the location and properties of any embedded high speed streams (HSSs) or stream interactions regions that form as the fast solar wind catches up to slow preceding wind. Additionally, this information is critical for understanding how a coronal mass ejection (CME) interacts with the solar wind during its propagation. We present the Mostly Empirical Operation Wind with a High Speed Stream (MEOW-HiSS) model, which runs nearly instantaneously. This model is derived from MHD simulations of an idealized HSS emanating from a circular coronal hole (CH). We split the MHD HSS radial profiles into small regions well-described by simple functions (e.g. flat, linear, exponential, sinusoidal) that can be constrained using the MHD values. We then determine how the region boundaries and the constraining values change with CH area and the distance of the HSS front. MEOW-HiSS requires the CH area and front distance and produces the corresponding radial profile with an error less than 10\% for most parameters. MEOW-HiSS produces profiles at subsequent times with almost no loss in accuracy. We also compare MEOW-HiSS results to four HSS observed in situ at 1 au. We present a method for determining MEOW-HiSS inputs from EUV images and use these values to hindcast the observed cases. We find average accuracies of 2.8 cm^-3 in the number density, 56.7 km/s in the radial velocity, 2.2 nT in the absolute radial magnetic field, 1.6 nT in the absolute longitudinal magnetic field, and 7x10^4 K in the temperature.

How to cite: Kay, C., Nieves-Chinchilla, T., Hofmeiseter, S., and Palmerio, E.: An Efficient, Time-Dependent High Speed Stream Model and Application to Solar Wind Forecasts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9811, https://doi.org/10.5194/egusphere-egu23-9811, 2023.

EGU23-10131 | ECS | Posters virtual | ST4.1

Analyzing the September 5, 2022, CME from a Space Weather perspective: Was this a “Carrington-type” event? 

Evangelos Paouris, Athanasios Kouloumvakos, Angelos Vourlidas, and Athanasios Papaioannou

The Coronal Mass Ejection of September 5, 2022, was the most extreme CME event ever observed and measured in-situ by spacecraft inside the corona (0.06 AU for Parker Solar Probe) and from multi-viewpoints ranging from 0.71 AU (Solar Orbiter) to ~1.0 AU (STEREO-A and SOHO). In this work, we evaluate the space weather significance of this event by examining the source region characteristics and its evolution as a function of time via a magnetic complexity index. We also examine the kinematics and energetics of the associated CME. It was a very fast and massive event, with a speed greater than 2200 km/s, and a mass of 2×1016 grams. These characteristics place this event in the top 1% of all the CMEs observed by SOHO/LASCO since 1996. It is therefore natural to ask “what if this CME was an Earth-directed one?”.

To answer this question, we put the CME and flare properties in the context of similar previous extreme events (the July 23, 2012, and March 7, 2012 eruptions) including the solar energetic particle (SEP) event characteristics. We find that, if this event was magnetically well-connected to Earth, it could have resulted in a ground level enhancement (GLE) event. We estimate the transit time and likely Dst values if this were an Earth-directed event.

How to cite: Paouris, E., Kouloumvakos, A., Vourlidas, A., and Papaioannou, A.: Analyzing the September 5, 2022, CME from a Space Weather perspective: Was this a “Carrington-type” event?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10131, https://doi.org/10.5194/egusphere-egu23-10131, 2023.

EGU23-11553 | ECS | Posters on site | ST4.1

The UNIGRAZ ESA H-ESC tool “STEREO+CH” – upgrade and preparation for cycle 25 

Daniel Milosic and Manuela Temmer

We present the ESA service STEREO+CH which forecasts the solar wind speed for Earth, based on persistence modeling from STEREO in situ measurements combined with multi-viewpoint EUV observational data. By comparing the fractional areas of coronal holes (CHs) extracted from EUV data of STEREO and SoHO/ SDO, we add an uncertainty level derived from changes in the CH areas, and apply those changes to the predicted solar wind speed profile at Earth (see Temmer, Hinterreiter, and Reiss, 2018). In principle, the service was developed to work with in situ and EUV data from the location behind Earth (e.g., future Vigil mission) providing a lead time of solar wind speed forecast for a couple of days. As STEREO-A will switch its location to ahead of Earth, we perform additional statistical studies and upgrade the service by adding co-latitude information of the CHs and dynamic thresholding for CH extraction to keep the performance level up. With that we make the ESA service ready for solar cycle 25.

How to cite: Milosic, D. and Temmer, M.: The UNIGRAZ ESA H-ESC tool “STEREO+CH” – upgrade and preparation for cycle 25, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11553, https://doi.org/10.5194/egusphere-egu23-11553, 2023.

EGU23-14274 | Orals | ST4.1

The HEliospheric pioNeer for sOlar and interplanetary threats defeNce (HENON) mission 

Monica Laurenza, Maria Federica Marcucci, Gaetano Zimbardo, Simone Landi, Daniele Paglialunga, Valerio Di Tana, Lorenzo Provinciali, Stefano Cicalò, Rami Vainio, Jussi Lehti, Zdeněk Němeček, Lubomir Prech, Jana Safrankova, Jonathan Eastwood, Patrick Brown, Roger Walker, Piers Jiggens, and Silvia Natalucci and the HENON Team

The HEliospheric pioNeer for sOlar and interplanetary threats defeNce (HENON) is a new mission concept conceived to address the widely recognized need to make a leap forward in the Space Weather (SWE) forecasting and science. The HENON baseline foresees one 12U CubeSat orbiting along a Distant Retrograde Orbit (DRO) of the Sun-Earth system, so that the HENON CubeSat will stay for a long period of time very far upstream of the Earth (well beyond L1 at least ~ 0.1 AU). HENON will embark a state of the art radiation monitor, which will provide high-resolution measurements of energetic particle spectra, making HENON the first mission ever providing a real time monitoring of the particle radiation environment in the deep space. This will enable the insight into the near-Earth spatial variations of SEP events giving rise to better boundary conditions for forecasting and nowcasting tools. The HENON mission also aims to embark payloads tailored for SWE observations, in order to pave the way for a significant improvement (several hours) of the forecasting horizons of geo-effective interplanetary structures (ICMEs, HSSs). HENON has important technological objectives including demonstration of the capability of the CubeSat technologies in deep space to reach both scientific and operational goals through the first ever operation in unexplored DRO orbits, thus paving the way for a future fleet of such CubeSats equally spaced along the DRO, which could provide continuous near real-time measurements for space weather forecasting. HENON is in the A/B study phase that is being developed in the framework of the ESA General Support Technology Program (GSTP). HENON is funded by the Italian Space Agency as part of the ALCOR programme.

How to cite: Laurenza, M., Marcucci, M. F., Zimbardo, G., Landi, S., Paglialunga, D., Di Tana, V., Provinciali, L., Cicalò, S., Vainio, R., Lehti, J., Němeček, Z., Prech, L., Safrankova, J., Eastwood, J., Brown, P., Walker, R., Jiggens, P., and Natalucci, S. and the HENON Team: The HEliospheric pioNeer for sOlar and interplanetary threats defeNce (HENON) mission, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14274, https://doi.org/10.5194/egusphere-egu23-14274, 2023.

EGU23-15416 | Posters on site | ST4.1

The phase relation of solar wind parameters with a solar activity proxy 

Raffaele Reda, Luca Giovannelli, and Tommaso Alberti

Manifestations of the solar magnetic activity in several forms, such as coronal mass ejections (CMEs), energetic particles and solar wind slow or high speed streams, strongly affect the terrestrial and circumterrestrial electromagnetic environments. Such phenomena primary affect the Earth's magnetosphere, which is perturbed and compressed, but subsequently they can have cascading effects on all the underlying systems, down to the upper atmosphere and the planetary surface. Because of the impact on the human activities too, it is of paramount importance to try to predict the time windows in which high speed solar wind is expected to occur. We study here the phase relation of a proxy of the solar activity, the Ca II K index, with solar wind parameters, such as speed and dynamic pressure. An unexpected relation between the parameters is found once the phases of the signals are considered, opening to the possibility to predict at least the expected mean solar wind conditions from the mentioned solar activity proxy. In this respect, it is essential to take into account for the presence of transients, which are responsible for the observed changes in the phase of the solar wind parameters. The method allows at least to predict the phase of the solar cycle in which high speed solar wind streams have the greatest probability of occurrence, as well as how their amplitudes are related to the solar cycle's one.

How to cite: Reda, R., Giovannelli, L., and Alberti, T.: The phase relation of solar wind parameters with a solar activity proxy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15416, https://doi.org/10.5194/egusphere-egu23-15416, 2023.

EGU23-15961 | ECS | Posters on site | ST4.1

A revised Database of CME characteristics from in-situ and remote observations 

Ronish Mugatwala, Gregoire Francisco, Simone Chierichini, Gianluca Napoletano, Raffaello Foldes, Dario Del Moro, Robertus Erdelyi, Luca Giovannelli, Giancarlo de Gasperis, and Enrico Camporeale

One of the goals of Space Weather studies is to achieve a better understanding of impulsive phenomena, such as
Coronal Mass Ejections (CMEs), in order to improve our ability to forecast them and reduce the risk to our
technologically driven society. To do this, it is crucial to assess the application of theoretical models or even to
create models that are entirely data-driven. The quality and availability of suitable data are of paramount
importance. We have already merged public data about CMEs from both in-situ and remote instrumentation in
order to build a database (DB) of CME properties. To evaluate the accuracy of such a DB and confirm the
relationship between in-situ and remote observations, we have employed the drag-based model (DBM). DBM is an
analytical model that assumes the aerodynamic drag caused by the surrounding solar wind to be the primary factor
in the interplanetary propagation of CMEs. Here, we explore the parameter space for the drag parameter and solar
wind speed using a Monte Carlo approach to analyse how well the DBM described the propagation of CMEs. With
this method, we validate and/or correct the initial hypotheses about solar wind speed, and also yield additional
information about CMEs. Using a data-driven approach, this procedure allows us to present a homogeneous,
reliable, and robust dataset for the investigation of CME propagation.

How to cite: Mugatwala, R., Francisco, G., Chierichini, S., Napoletano, G., Foldes, R., Del Moro, D., Erdelyi, R., Giovannelli, L., de Gasperis, G., and Camporeale, E.: A revised Database of CME characteristics from in-situ and remote observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15961, https://doi.org/10.5194/egusphere-egu23-15961, 2023.

EGU23-17086 | ECS | Posters on site | ST4.1

Statistical analysis of CME-flare relationship in Solar Cycle 24 

Luca Giovannelli, Francesco Berrilli, and Dario Del Moro

The prediction of both solar flares and coronal mass ejections is of paramount importance for the impact of space weather on our technology-based society. We revise the statistics of CME-flare relationship on Solar Cycle 24  using the GOES database and a CME database recently released. The latter was developed using  the Drag-Based Model (DBM) to assess the quality of such a database, distinguishing accelerated and decelerated CMEs. Furthermore we exploit the R* and D parameters based on the magnetic flux measured in the proximity of the Polarity Inversion Lines in active regions to classify flaring regions in different classes. Finally we study the CME-flare relationship for those classes for Solar Cycle 24.

How to cite: Giovannelli, L., Berrilli, F., and Del Moro, D.: Statistical analysis of CME-flare relationship in Solar Cycle 24, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17086, https://doi.org/10.5194/egusphere-egu23-17086, 2023.

EGU23-793 | ECS | Posters on site | ST4.2

Toward last-minute warning of local aurora activity and large dB/dt in Kiruna 

Arnau Busom Vidal, Masatoshi Yamauchi, and Urban Brändström

In spaceweather warning, last-minute (< 10 min) warning of the local ionospheric and geomagnetic activities using local measurements is as important as midterm (about 1 hour using Sun-Earth L1 monitor) and long term (> day using solar data) warning. We the first step, we developed warning system for different levels auroral activities using all-sly camera data only: one is sudden and significant intensification of auroral arc with expanding motion (we call it "Local-Arc-Breaking"), and the other is activated local aurora which is often (submitted to Geoscientific Instrumentation, Methods and Data Systems: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-331/).

We now combined geomagnetic data to this warning. We used 1-sec geomagnetic (B) data to drive dB/dt, and took its average every minute to further separate the activity level of the aurora, from previous three levels (using only aurora) to seven levels. Here, the highest level (dB/dt > 5 nT/s) means potential risk of hazard by high geomagnetic induced current (GIC).

We then obtained probability of having higher level of the activity within the following 15 minutes. Particular interest is the probability of Local-Arc-Breaking from precursors (four different levels) and large dB/dt (> 5 nT/s) event. Since the rise time of big activities (both aurora and dB/dt) is very short, nearly half the case of such occurrence is within one minutes, and 10 minute is sufficient. For the data we used winter 2021/2022 season data (from November 2021 to April 2022). The data is limited because we have different camera before. 

Out of four possible precursors, three precursors give 50-70% probability of the Local-Arc-Breaking within 10 minutes. Once the auroral activity level reaches the Local-Arc-Breaking, and if dB/dt exceed 2 nT/s, we expect large dB/dt > 5 nT/s with 20% (with large uncertainty for the last one). This opens up a possibility of using auroral data in improving the prediction of the GIG events.

How to cite: Busom Vidal, A., Yamauchi, M., and Brändström, U.: Toward last-minute warning of local aurora activity and large dB/dt in Kiruna, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-793, https://doi.org/10.5194/egusphere-egu23-793, 2023.

EGU23-1377 | ECS | Orals | ST4.2

Analysis of the geoelectric field in Sweden over solar cycles 23 and 24: spatial and temporal variability during strong GICs events 

Vanina Lanabere, Andrew Dimmock, Lisa Rosenqvist, Liisa Juusola, and Ari Viljanen

Extreme space weather events can produce geomagnetically induced currents (GICs) that flow along long conductor systems such as power grids and pipelines. GICs can interrupt the operation of these systems by damaging transformers and increasing the rate of pipeline corrosion. GICs depend on the enhancement of the geoelectric field, where the magnitude, geographic location, and occurrence depend on the solar wind-magnetospheric-ionospheric coupling processes and the ground conductivity. Thus, countries at high latitudes are potentially more vulnerable to GICs due to higher geomagnetic activity.

Magnetic field measurements (e.g. dB/dt) have been used for a long time as a proxy for GICs with some success. However, studying the behaviour of the geoelectric field is required to fully understand the GIC response during extreme space weather events. In this study, the geoelectric field was computed using data from the IMAGE network and a 1D conductivity model (SMAP) across Sweden. A 19-year statistical analysis of the daily maximum magnitude of the geoelectric field (E) has been performed for solar cycles 23 and 24. We examine the temporal and spatial distribution of the geoelectric field in Sweden to determine the importance of including the ground conductivity when assessing the strongest events and their implications to GICs.

 We found that the daily maximum E is more frequently registered in the dusk sector related to the eastward convection electrojet and a second relative maximum is observed in the dawn sector related to westward convection electrojet. The stronger E values are related to well-known extreme space weather events. However, these events produce different responses at different latitudes due to the changes in ground conductivity and ionospheric response. Therefore, the strongest geoelectric fields at different geographical locations are not all driven by the same events.

How to cite: Lanabere, V., Dimmock, A., Rosenqvist, L., Juusola, L., and Viljanen, A.: Analysis of the geoelectric field in Sweden over solar cycles 23 and 24: spatial and temporal variability during strong GICs events, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1377, https://doi.org/10.5194/egusphere-egu23-1377, 2023.

EGU23-2048 | Posters on site | ST4.2 | Highlight

Forecasting High-Latitude Ionospheric Convection Using the BAS Reanalysis of SuperDARN Data 

Mai Mai Lam, Robert Shore, Gareth Chisham, Mervyn Freeman, Adrian Grocott, Maria-Theresia Walach, and Lauren Orr

Forecasting of the effects of thermospheric drag on satellites will be improved significantly with more accurate modelling of space weather effects on the high-latitude ionosphere, in particular the Joule heating arising from electric field variability. This is the largest uncertainty in orbit prediction for satellites and space debris. We use a regression analysis to build a forecast model of the ionospheric convection E×B drift velocity which is driven by relatively few solar and solar wind variables. The model is developed using a solar cycle’s worth (1997 to 2008 inclusive) of 5-minute resolution reanalysis data derived from Super Dual Auroral Radar Network (SuperDARN) line-of-sight observations of the convection velocity across the high-latitude northern hemisphere ionosphere. At key stages of development of the forecast model, we use the Priestley skill score to see how well the model reproduces the reanalysis dataset. The final forecast model is driven by four variables: (1) the interplanetary magnetic field component By, (2) the solar wind coupling parameter epsilon ε, (3) a trigonometric function of day of year, (4) the monthly f10.7 index. The forecast model can reproduce the reanalysis plasma velocities, with a characteristic skill score of 0.7. The forecast and reanalysis data compare best around the solar maximum of 2001. The forecast skill is lower around solar minimum, due to occasional limitations in the geographical and temporal coverage of the SuperDARN instrumentation. In addition, this may also indicate the need to modify our model of driving processes around the minimum of the solar cycle.

How to cite: Lam, M. M., Shore, R., Chisham, G., Freeman, M., Grocott, A., Walach, M.-T., and Orr, L.: Forecasting High-Latitude Ionospheric Convection Using the BAS Reanalysis of SuperDARN Data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2048, https://doi.org/10.5194/egusphere-egu23-2048, 2023.

EGU23-2728 | ECS | Orals | ST4.2

The path from scientific to operational flare forecasting: a deep learning approach 

Sabrina Guastavino, Francesco Marchetti, Federico Benvenuto, Cristina Campi, Anna Maria Massone, and Michele Piana

In our view, machine/deep learning for flare forecasting is still more a promise for future scenarios than the reference framework for current operational facilities. This delay from the application of AI methods in research settings to their use for real-time forecasting is probably due to the persistence of technical open issues involving, by instance, the optimization strategy of the training phase, the quantitative assessment of the prediction performances, the reduction of the computational burden. This talk proposes a video-based deep learning approach to flare forecasting in which the optimization of the network’s parameters is realized by means of a probabilistic score-oriented loss function, the training procedure accounts for the part of the solar cycle progression when the prediction is requested, and the prediction performances are assessed by means of value-weighted skill scores that give greater importance to the values of the prediction than to its quality. The talk will also show the operational potentialities of this approach and discuss how feature selection may reduce the information redundancy, thus increasing the computational efficiency.

How to cite: Guastavino, S., Marchetti, F., Benvenuto, F., Campi, C., Massone, A. M., and Piana, M.: The path from scientific to operational flare forecasting: a deep learning approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2728, https://doi.org/10.5194/egusphere-egu23-2728, 2023.

EGU23-3356 | Orals | ST4.2

Running web-based model chains via ESA’s Virtual Space Weather Modelling Centre 

Stefaan Poedts and the VSWMC-P3 team

The ESA Virtual Space Weather Modelling Centre (VSWMC) project was defined as a long term project including different successive parts. Parts 1 and 2 were completed in the first 4-5 years and designed and developed a system that enables models and other components to be installed locally or geographically distributed and to be coupled and run remotely from the central system. A first, limited version went operational in May 2019 under the H-ESC umbrella on the ESA SSA SWE Portal. It is similar to CCMC but interactive (no runs on demand) and the models are geographically distributed and coupled over the internet. The goal of the ESA project "Virtual Space Weather Modelling Centre - Part 3" (2019-2022) was to further develop the Virtual Space Weather Modelling Centre, building on the Part 2 prototype system and focusing on the interaction with the ESA SSA SWE system. The objectives and scope of this new project include maintaining the current operational system, the efficient integration of 11 new models and many new model couplings, including daily automated end-to-end (Sun to Earth) simulations, the further development and wider use of the coupling toolkit  and front-end GUI, making the operational system more robust and user-friendly.

The 11 new models that have been integrated are Wind-Predict (a global coronal model from CEA, France), the Coupled Thermosphere/Ionosphere Plasmasphere (CTIP) model, Multi-VP (another global coronal model form IRAP/CNRS, France), the BIRA Plasma sphere Model of electron density and temperatures inside and outside the plasmasphere coupled with the ionosphere (BPIM, Belgium), the SNRB  (also named SNB3GEO) model for electron fluxes at geostationary orbit (covering the GOES 15 energy channels >800keV and >2MeV) and the SNGI geomagnetic indices Kp and Dst models (University of Sheffield, UK), the SPARX Solar Energetic Particles transport model (University of Central Lancashire, UK), Spenvis DICTAT tool for s/c internal charging analysis (BISA, Belgium), the Gorgon magnetosphere model (ICL, UK), and the Drag Temperature Model (DTM) and operations-focused whole atmosphere model MCM being developed in the H2020 project SWAMI. Many new couplings have also been implemented which can be used interactively. Moreover, daily runs are implemented of several model chains covering the whole Sun-to-Earth domain. The results of these daily runs are made available to all VSWMC users. We will provide an overview of the state-of-the-art, including the new available model couplings and daily model chain runs, and demonstrate the system.

How to cite: Poedts, S. and the VSWMC-P3 team: Running web-based model chains via ESA’s Virtual Space Weather Modelling Centre, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3356, https://doi.org/10.5194/egusphere-egu23-3356, 2023.

EGU23-3447 | Posters on site | ST4.2

Reproducing storm-time densities with Kp, Hpo and TIMED/SABER CO2 cooling power 

Sean Bruinsma and Sophie Laurens

A major application of semi-empirical thermosphere specification models is in the computation of the atmospheric drag force in the orbit determination and prediction of spacecraft as well as debris. The models provide low spatial and temporal resolution average (climatological) predictions of temperature, total and partial densities of the main constituents as a function of location (altitude, latitude, longitude, local solar time), solar and geomagnetic activity, and season.

 

The research DTM2020 thermosphere model uses a new driver for geomagnetic activity, the hourly Hp60 index (https://doi.org/10.5880/Hpo.0001) instead of the three-hourly Kp. However, thermosphere cooling due to enhanced C02 and NO production in particular during storms is not explicitly taken into account in the semi-empirical models. In this study, we will use density observations of CHAMP, GOCE, GRACE, and Swarm, the Kp and Hpo indices, and the TIMED/SABER measured CO2 and NO cooling power per profile and per day, for selected geomagnetic storms. We will investigate the benefits of Hpo vs Kp, and if it is possible to reproduce storm density more precisely in semi-empirical thermosphere models by adding observed cooling power as model driver.

How to cite: Bruinsma, S. and Laurens, S.: Reproducing storm-time densities with Kp, Hpo and TIMED/SABER CO2 cooling power, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3447, https://doi.org/10.5194/egusphere-egu23-3447, 2023.

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. We recently showed [1,2] that the Hilbert transform of the sunspot record can be used to map the variable cycle length onto a regular 'clock' where each cycle has the same duration in Hilbert analytic phase.  Extreme geomagnetic storms rarely occur within the quiet part of the cycle which is a fixed interval of analytic phase on the clock; there is a clear active-quiet switch-off and quiet-active switch-on of activity. Some of the most extreme geomagnetic storms have occurred just at the switch-on time, rather than at solar maximum, so that determining when this will occur could provide guidance on planning and preparedness which necessarily must balance resilience against cost. Here [3] we show how the times of the switch-on/off can be determined directly from the sunspot time-series, without requiring a Hilbert transform.  We propose a method- charting- that can be used to combine observations, and both historical and current reports of societal impacts, to improve our understanding of space weather risk.

[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, S. W. McIntosh, R. J. Leamon, N. W. Watkins, The Sun's magnetic (Hale) cycle and 27 day recurrences in the aa geomagnetic index. Ap. J. (2021) doi: 10.3847/1538-4357/ac069e

[3] S. C. Chapman, Charting the Solar Cycle, Front. Astron. Space Sci. - Space Physics, in press (2022) doi: 10.3389/fspas.2022.1037096

How to cite: Chapman, S.: Charting the solar cycle variation of the climate of space weather and its impacts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4010, https://doi.org/10.5194/egusphere-egu23-4010, 2023.

EGU23-4113 | ECS | Posters virtual | ST4.2

Evaluation of total electron content derived from the spaceborne receivers of GRACE/GRACE-FO missions 

Yuhao Zheng, Chao Xiong, Haicheng Jiang, Fan Yin, Claudia Stolle, and Guram Kervalishvili

The Gravity Recovery and Climate Experiment (GRACE) and its follow-on mission GRACE-FO are gravity satellites jointly developed by the National Aeronautics and Space Administration (NASA) and German Aerospace Center (DLR), which are composed of two satellites. Such tandem satellite missions provide us with a good opportunity to evaluate the ionospheric total electron content (TEC) derived from their onboard global positioning system (GPS) receivers. In addition, the K-band ranging system (KBR) between two satellites provides also the in-situ electron density (Ne) at the satellite orbits, which can help further to evaluate the reliability of TEC. By combing the observations from GRACE and GRACE-FO, 20 years of data (from 2002 to 2022) have been accumulated to analyze the solar cycle dependence of TEC and Ne at the topside ionosphere. Our results show that the TEC from the tandem satellites is generally the same, but slight differences can still be found, showing solar cycle and local time dependences. In addition, we found that the TEC differences between the tandem satellites of GRACE are somehow smaller than that of GRACE-FO, and the consistency between the TEC and inter-satellite electron density results of GRACE is also better.

How to cite: Zheng, Y., Xiong, C., Jiang, H., Yin, F., Stolle, C., and Kervalishvili, G.: Evaluation of total electron content derived from the spaceborne receivers of GRACE/GRACE-FO missions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4113, https://doi.org/10.5194/egusphere-egu23-4113, 2023.

EGU23-4467 | ECS | Orals | ST4.2

Thermospheric mass density variations based on GRACE-FO during the ascending phase of solar cycle 25 

Bowen Wang, Xiangguang Meng, Yueqiang Sun, Benjamin Männel, and Jens Wickert

High-resolution thermospheric mass density (TMD) measurements from Low Earth Orbit (LEO) Satellites are valuable to accurately estimate the short-term atmosphere abrupt disturbances, triggered by magnetospheric forcing. A good characterization of TMD variation ahead of the arrival geomagnetic storms can benefit LEO operations and crucial for both orbit propagation and collision avoidance. In this contribution, we will reveal the most probable feature of TMD variation during the initial stage of solar cycle 25, at the same time, we proved Wygant function as a better geomagnetic events indicator.

In this study, GRACE-FO 10s accelerometer-derived TMD measurements were employed and normalized at altitude of 505km by the NRLMSISE-00 (Naval Research Laboratory Mass Spectrometer and Incoherent Scatter Radar Exosphere 2000) empirical atmosphere model to investigate the status of solar cycle 25 between September 1 and December 31, 2020. With the high-inclination orbit global coverage, three magnetic latitude regions were separated and divided into day and nighttime using magnetic local times (MLT). 4-month enhancing disturbances observations suggest solar activities will shift from its relatively quiet condition to a much more active behavior, which reveal unexpected dependencies on the temporal and spatial characteries. Our detailed analysis shows that (1) TMD spreads from high latitudes to low latitudes and as same as time lag, (2) TMD enhancement in the Southern hemisphere is more intense than in the Northern one, reaching peak value around 15:00 MLT; geomagnetic activities cause TMD to increase up to 0.86×10-13 kg/m3 at night side, 3.4×10-13 kg/m3 at day side, and (3) the TMD enhancement was symmetric in both N- and S- hemispheres before the equinox. In general, thermospheric mass density analysis reveals the significant impact of solar and geomagnetic activities, providing the most relevant and probable characteristic of the TMD disturbances driven by solar wind.

Additionally, we try to use different geomagnetic indices for a complete description of geomagnetic storms and their phases. The S10.7 index is used as a proxy for solar irradiation. These indicators show high correlation with the TMD variation during recurrent geomagnetic activities. What’s more, the cross-correlation analysis reflects a high correlation of to the Wygant function EWAV found both at three latitude bins.

Even thought our study is considered a minor to moderate geomagnetic storm of the upcoming solar cycle 25 maximum, the high-speed stream injection into the thermosphere still caused thermosphere expansion that significantly enhanced the neutral density in the LEO environment. Therefore, all these findings provide a possibility to improve our understanding of LEO orbital drag.

How to cite: Wang, B., Meng, X., Sun, Y., Männel, B., and Wickert, J.: Thermospheric mass density variations based on GRACE-FO during the ascending phase of solar cycle 25, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4467, https://doi.org/10.5194/egusphere-egu23-4467, 2023.

EGU23-5010 | ECS | Orals | ST4.2

Automatic Detection of Interplanetary Coronal Mass Ejections in Solar Wind in Situ Data 

Hannah Theresa Rüdisser, Andreas Windisch, Ute V. Amerstorfer, Tanja Amerstorfer, Christian Möstl, Rachel L. Bailey, and Martin A. Reiss

Interplanetary coronal mass ejections (ICMEs) are one of the main drivers for space weather disturbances. In the past, different approaches have been used to automatically detect events in existing time series resulting from solar wind in situ observations. However, accurate and fast detection still remains a challenge when facing the large amount of data from different instruments. For the automatic detection of ICMEs we recently published a deep learning pipeline which has been trained, validated and tested on Wind, STEREO-A and STEREO-B data. We shortly present results of this work and talk about our current attempt to extend its application to a real time scenario in order to investigate its eligibility for functioning as an early warning system.

How to cite: Rüdisser, H. T., Windisch, A., Amerstorfer, U. V., Amerstorfer, T., Möstl, C., Bailey, R. L., and Reiss, M. A.: Automatic Detection of Interplanetary Coronal Mass Ejections in Solar Wind in Situ Data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5010, https://doi.org/10.5194/egusphere-egu23-5010, 2023.

EGU23-5613 | ECS | Orals | ST4.2

Forecasting ICME induced Satellite Orbit Decays 

Lukas Drescher, Sofia Kroisz, Sandro Krauss, Manuela Temmer, Barbara Suesser-Rechberger, and Andreas Strasser

Geomagnetic storms are capable of triggering thermospheric density variations which in turn have an influence on the trajectory of low Earth orbiting satellites (LEO). The strongest of these disturbances of the thermosphere are caused by interplanetary coronal mass ejections (ICMEs). Due to increases in the neutral mass density during such ICME induced geomagnetic storms the altitude of satellites will decrease. Therefore, ICME induced orbit decays are important for long-term orbit prediction as well as short-term as the prominent example of the so called ‘Starlink’ event of February 2022 showed where 40 satellites reentered the atmosphere.

In order to calculate the ICME induced orbit decay we calculated the thermospheric neutral mass density through the deceleration due to drag. This is done either with an observation approach using the high orbiting global navigation satellite system (GNSS) or calibrated data from onboard accelerometers. We then relate the solar wind plasma and magnetic field measurements taken at L1 from the ACE (Advanced Composition Explorer) and the DSCOVR (Deep Space Climate Observatory) satellites to the calculated ICME induced orbit decays. 299 ICMEs occurred during the operation of the GRACE (Gravity Recovery And Climate Experiment) satellite which orbits at an altitude of around 490 km. Analysis of the ICME induced orbit decays and the interplanetary magnetic field at L1 show a strong correlation as well as a time delay between the ICME and the associated thermospheric response of around 15 hours on average. This correlation is implemented in the real time forecasting tool SODA (Satellite Orbit DecAy). Because the ICME induced orbit decay strongly depends on the altitude we additionally processed data from the CHAMP (CHAllenging Minisatellite Payload) satellite mission to cover the range of 400 km altitude. The GRACE focused forecast algorithm SODA is part of the project SWEETS and ESPRIT, which will be implemented in the ESA Space Safety Program (Ionospheric Weather Expert Service Center) in 2023.

How to cite: Drescher, L., Kroisz, S., Krauss, S., Temmer, M., Suesser-Rechberger, B., and Strasser, A.: Forecasting ICME induced Satellite Orbit Decays, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5613, https://doi.org/10.5194/egusphere-egu23-5613, 2023.

Geomagnetic activity is driven by the variable solar wind and is often used as an indirect measure for energetic particle precipitation (EPP) from space into Earth’s atmosphere. A growing number of studies has shown that geomagnetic activity via EPP can intensify the wintertime polar vortex in the stratosphere by forming ozone-depleting nitrogen and hydrogen oxides through different chemical reactions, which then influence the atmosphere’s radiative balance and dynamics. The polar vortex variations also influence the ground weather and project onto the variability of the Northern Annular Mode (NAM), which describes the prevailing pressure pattern in the Northern hemisphere and is the most important factor influencing the winter weather, e.g., in Northern Europe. A stronger (weaker) vortex is associated to positive (negative) NAM phase and tends to cause warmer and wetter (colder and drier) winter weather in Scandinavia and Northern Eurasia. Recent studies have also shown that the EPP influence on the polar vortex and NAM is strongly dependent on the phase of the Quasi-Biennial Oscillation (QBO) of stratospheric equatorial zonal winds.  When QBO-winds at 30 hPa pressure level are easterly the EPP influence on the polar vortex and NAM is stronger.

It is known that prevailing weather conditions have a huge effect on wintertime electricity consumption, e.g., in these Northern European regions, notably in Finland and Scandinavian countries. During cold weather more electricity is consumed for heating purposes while the opposite is true during milder winter weather.

The EPP-related influence on winter time climate variability implies a new and so far unexplored connection by which space weather and space climate affects the modern technological society. In this study we consider this question for the first time and quantify the influence of geomagnetic activity on the inter-annual variations of wintertime electricity consumption in Finland from 1980s until present also taking into account of the phase of the QBO. We first demonstrate that the wintertime electricity consumption in Finland depends strongly on Finland’s average temperature. We then show that geomagnetic activity has a strong influence on Finland’s wintertime average temperature via the polar vortex and NAM variability. We then show that during easterly QBO phase the geomagnetic activity has a clear and statistically significant influence on the wintertime electricity consumption in Finland and can explain a large fraction of its inter-annual variability. During westerly QBO phase such influence is not observed.

How to cite: Juntunen, V. and Asikainen, T.: Influence of geomagnetic activity on the wintertime electricity consumption in Finland via Northern Annular Mode, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6389, https://doi.org/10.5194/egusphere-egu23-6389, 2023.

EGU23-7023 | Orals | ST4.2

Multiscale properties of the ionospheric electric field in the auroral region from a one-year survey with CSES-01. 

Emanuele Papini, Mirko Piersanti, Piero Diego, Giuseppe Consolini, Giulia D'Angelo, Dario Recchiuti, and Zeren Zhima

We present the results of a study of the electric field properties in the auroral oval (AO) region. We exploit more than one year of electric field measurements taken by the EFD instrument onboard the China-Seismo-Electromagnetic Satellite 01 (CSES-01) spacecraft, orbiting sun-synchronously at around 500 km of altitude inside the Earth ionosphere. To exploit the high temporal resolution of EFD, we devise a new technique that allows to detect the crossing of the AO by CSES-01 using electric field measurements only. This new technique combines a median-weighted local variance measure and Iterative Filtering to automatically isolate high levels of electromagnetic activity caused by, e.g., particle precipitation and Field Aligned Currents (FAC) at auroral latitudes. We validate this new method on few selected orbits against other standard proxies, such as the SWARM single-FAC product and the auroral radiance emission measured by SSUSI onboard the DMSP constellation. Furthermore, we identify ~3 000 orbits (on a dataset of ~10 000) of high geomagnetic activity where CSES either crossed the AO boundary or the polar cap region and characterize the multiscale (down to characteristic electron scales) statistical properties of the electric field. This work represents the first systematic study of the Auroral electric field, with many potential applications to space-weather studies, thanks to the large amount of continuous observations of the ionosphere carried out by CSES-01. 

How to cite: Papini, E., Piersanti, M., Diego, P., Consolini, G., D'Angelo, G., Recchiuti, D., and Zhima, Z.: Multiscale properties of the ionospheric electric field in the auroral region from a one-year survey with CSES-01., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7023, https://doi.org/10.5194/egusphere-egu23-7023, 2023.

EGU23-7754 | ECS | Orals | ST4.2

ROBUST – a radio burst identification algorithm using the e-CALLISTO station at University of Graz 

Lukas Höfig, Manuela Temmer, Florian Koller, Lukas Drescher, and Christian Monstein

The primary condition to produce eruptive solar flare events and solar energetic particles is the opening of magnetic field lines into interplanetary space. In that respect, real-time radio spectra cover important observational information with substantial lead time for space weather warnings. For Space Weather forecasting an objective detection of radio type III and type II bursts is key. We present an algorithm using multiple e-CALLISTO radio stations to detect a) type III bursts, distinguishing between confined and eruptive flares and b) type II bursts, identifying shocks produced by fast coronal mass ejections. We present statistical results for the detection rates and an outlook of the implementation of the algorithm to the e-CALLISTO station at the University of Graz in Austria as well as to the entire international network.

How to cite: Höfig, L., Temmer, M., Koller, F., Drescher, L., and Monstein, C.: ROBUST – a radio burst identification algorithm using the e-CALLISTO station at University of Graz, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7754, https://doi.org/10.5194/egusphere-egu23-7754, 2023.

EGU23-8128 | Orals | ST4.2 | Highlight

Prediction of Adverse effects of Geomagnetic storms and Energetic Radiation (PAGER) 

Stefano Bianco, Yuri Shprits, Ruggero Vasile, Michael Wutzig, Dedong Wang, Melanie Burns, Bernhard Haas, 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

An update on our project aiming to provide space weather predictions that will be initiated from observations on the Sun and to predict radiation in space and its effects on satellite infrastructure. Real-time predictions and a historical record of the dynamics of the cold plasma density and ring current allow for evaluation of surface charging, and predictions of the relativistic electron fluxes will allow for the evaluation of deep dielectric charging. The project aims to provide a 1-2 day probabilistic forecast of ring current and radiation belt environments, which will allow satellite operators to respond to predictions that present a significant threat. As a backbone of the project, we use the most advanced codes that currently exist and adapt existing codes to perform ensemble simulations and uncertainty quantifications. This project includes a number of innovative tools 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 geomagnetic Kp index and plasma density. The developed codes may be used in the future for realistic modelling of extreme space weather events. The PAGER consortium is made up of leading academic and industry experts in space weather research, space physics, empirical data modelling, and space environment effects on spacecraft from Europe and the US.

How to cite: Bianco, S., Shprits, Y., Vasile, R., Wutzig, M., Wang, D., Burns, M., Haas, B., 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), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8128, https://doi.org/10.5194/egusphere-egu23-8128, 2023.

EGU23-8880 | Posters on site | ST4.2

Ground and space data products provided by GFZ to the ESA Space Weather Service Network 

Guram Kervalishvili, Jan Rauberg, Jürgen Matzka, and Monika Korte

The Space Weather (SWE) Service Network of the European Space Agency’s (ESA’s) Space Safety Programme provides timely and reliable space weather information to end users allowing the mitigation and prevention of the impact of hazards from space on the communication and navigation systems, power grids, and aviation, etc. The SWE Service Network consists of 5 Expert Service Centres (ESCs), Solar Weather, Space Radiation, Ionospheric Weather, Geomagnetic Conditions, and Heliospheric Weather, which are distributed and established across Europe providing coverage of space weather phenomena and impacts on ground and space-based infrastructure. Note that a free registration at the ESA's SWE portal is necessary to get access to the protected applications or products.

Here, we give an overview of 18 products that currently are provided by GFZ in the Ionospheric Weather ESC (I-ESC) and Geomagnetic Conditions ESC (G-ESC). These products are derived from the Low Earth Orbiting (LEO) satellite and ground-based observations. In I-ESC, the following Swarm mission products are provided: Rate Of the change of TEC (ROT), Total Electron Content (TEC), in-situ electron density (Ne), Ionospheric Bubble Index (IBI), Rate Of the change of TEC Index (ROTI). And in G-ESC: the location and intensity level of the Polar Electrojet (PEJ), Field-Aligned Currents (FACs), and Vector Magnetic Field (MAG) components. The following global geomagnetic indices are provided in G-ESC, nowcast Kp (three-hourly), Hp60 (one-hourly and open-ended), Hp30 (half-hourly and open-ended) indices, most recent definitive Kp index, Kp, Ap, Hp60, ap60, Hp30, ap30 indices on tabular form, Kp and Ap (since 1932), Hp60, ap60, Hp30 and ap30 (since 1995) indices archive.

How to cite: Kervalishvili, G., Rauberg, J., Matzka, J., and Korte, M.: Ground and space data products provided by GFZ to the ESA Space Weather Service Network, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8880, https://doi.org/10.5194/egusphere-egu23-8880, 2023.

EGU23-9081 | Orals | ST4.2 | Highlight

A cross-discipline approach to examine the physical links between Weather in Space and the Lower Atmosphere 

Matthew Taylor, Rune Floberghagen, Anja Strømme, Michael Rast, Lisa Baddeley, Michel Blanc, Eric Donovan, Eelco Doornbos, Roger Haagmans, Kirsti Kauristie, Larry Kepko, Steve Milan, Hermann Opgenoorth, Noora Partamies, Tim Stockdale, and Claudia Stolle

Earth’s atmosphere provides the background for the “sea of plasmas” surrounding Earth via its Ionosphere and the upper and middle Atmosphere, providing an interface layer through which a broad diversity of solar-terrestrial energy transfer processes takes place. Developing an integrative understanding of global geospace energy transfer processes affecting this layer is a major scientific challenge with important societal implications. The disciplines covering this interaction have a large, diverse and active international community, with significant expertise and heritage in the European Space Agency and Europe. Several ESA directorates have activities directly connected with this topic, and an ESA Heliophysics Working group has been appointed by several ESA Directors, under the direction of the ESA Director General, to work on optimizing synergies and to act as a focus for discussion, inside ESA, of the scientific interests of the Heliophysics community.

Very recently, a Forum at the International Space Science Institute was set up, involving some of the above WG, to look towards developing a deeper understanding of the solar-terrestrial interactions between the Ionosphere and the upper- and middle atmosphere, thus possibly enabling the detection of signatures by natural and anthropogenic hazards.

This presentation will provide a brief introduction to ongoing internal ESA cross discipline approaches, and then note some of the outcomes of this recent ISSI forum to set out a pathway to address this intriguing topic.

How to cite: Taylor, M., Floberghagen, R., Strømme, A., Rast, M., Baddeley, L., Blanc, M., Donovan, E., Doornbos, E., Haagmans, R., Kauristie, K., Kepko, L., Milan, S., Opgenoorth, H., Partamies, N., Stockdale, T., and Stolle, C.: A cross-discipline approach to examine the physical links between Weather in Space and the Lower Atmosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9081, https://doi.org/10.5194/egusphere-egu23-9081, 2023.

EGU23-9382 | ECS | Posters on site | ST4.2

Comparing extreme event statistics in Dst, SYM-H and SMR geomagnetic indices. 

Aisling Bergin, Sandra Chapman, Nicholas Watkins, Nicholas Moloney, and Jesper Gjerloev

Extreme space weather events are rare, and quantifying their likelihood is challenging, often relying on geomagnetic indices obtained from ground-based magnetometer observations that span multiple solar cycles. The Dst index ring-current monitor, derived from an hourly average over four low-latitude stations, is a benchmark for extreme space weather events, and has been extensively studied statistically. We apply extreme value theory (EVT) to two geomagnetic ring current indices: SMR, (derived from up to 120 stations) and SYM-H (derived from 6 stations). EVT analysis reveals a divergence between the return level found for Dst, and those for SMR and SYM-H, that increases non-linearly with return period. For return periods below 10 years, hourly averaged SMR and SYM-H have return levels similar to Dst, but at return periods of 50 and 100 years, they respectively exceed that of Dst by about 10% and 15% (SYM-H) and about 7% and 12% (SMR). One minute resolution SMR and SYM-H return levels progressively exceed that of Dst; their 5, 10, 50 and 100 year return levels exceed that of Dst by about 10%, 12%, 20% and 25% respectively. Our results suggest that for more extreme events, these geomagnetic indices are not directly interchangeable, instead they contain different, complimentary information and should be used together in any detailed analysis. Such an analysis may improve the correlation between return levels and the impact of severe geomagnetic storms 

How to cite: Bergin, A., Chapman, S., Watkins, N., Moloney, N., and Gjerloev, J.: Comparing extreme event statistics in Dst, SYM-H and SMR geomagnetic indices., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9382, https://doi.org/10.5194/egusphere-egu23-9382, 2023.

EGU23-10055 | ECS | Posters on site | ST4.2

Neural network model of Electron density in the Topside ionosphere (NET) 

Artem Smirnov, Yuri Shprits, Hermann Lühr, Fabricio Prol, and Chao Xiong

The ionosphere is an ionized part of the upper atmosphere, where the number of electrons in is large enough to affect the propagation of electromagnetic signals, including those of the GNSS systems. Therefore, knowing electron density values in the ionosphere is crucial for both industrial and scientific applications. Here, we employ the radio occultation profiles collected by the CHAMP, GRACE, and COSMIC missions, to model the electron density in the topside ionosphere. We assume a linear decay of scale height with altitude and create a model of 4 parameters, namely the F2-peak density and height (NmF2 and hmF2) and the slope and gradient of scale height in the topside (H0 and dHs/dh). The resulting model (NET) is based on feedforward neural networks and takes as input the geographic and geomagnetic position, the solar flux and geomagnetic indices. The resulting density reconstructions are validated on more than a hundred million in-situ measurements from CHAMP, CNOFS and Swarm satellites, as well as on the GRACE/KBR data, and the developed model is compared to several topside options of the Internation Reference Ionosphere (IRI) model. The NET model yields highly accurate reconstructions of electron density in the topside ionosphere and gives unbiased predictions for all seasonal and solar activity conditions.

How to cite: Smirnov, A., Shprits, Y., Lühr, H., Prol, F., and Xiong, C.: Neural network model of Electron density in the Topside ionosphere (NET), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10055, https://doi.org/10.5194/egusphere-egu23-10055, 2023.

EGU23-11294 | Posters on site | ST4.2

Forecasting extreme geomagnetic storms using different statistical models 

Ting Wang, Matthew Parry, Craig Rodger, Jessica Allen, and Tanja Petersen

Extreme geomagnetic storm events could cause hazardous damage to the technological infrastructure that increasingly underpins modern society. Being able to forecast the next extreme geomagnetic storm is thus crucial to navigating risks in the 21st century. There have been quite a number of studies on using extreme value theory to forecast future extreme geomagnetic storms. However, to the best of our knowledge, each study selects one model and one estimation method. In this study, we demonstrate that different estimation methods for the same extreme value model and different extreme value models can produce very different estimates of return levels when applied to the same dataset. We propose to use the average of the estimated return levels from different models and different estimation methods to produce more robust and reliable forecasts.

We apply this method to the geomagnetic field data measured in every minute in the period between 1994 and 2019 at Eyrewell, Canterbury, New Zealand. We focus on the horizontal components, and estimate the return levels of the ramp change in the horizontal component. The resulting return levels for the ramp change in the horizontal component using different types of models and different estimation methods show the importance of using model-averaged forecasts.

In this presentation, we also demonstrate forecasts of future geomagnetic storms using counting processes applied to the wavelet spectrum. 

How to cite: Wang, T., Parry, M., Rodger, C., Allen, J., and Petersen, T.: Forecasting extreme geomagnetic storms using different statistical models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11294, https://doi.org/10.5194/egusphere-egu23-11294, 2023.

The Sub-Auroral Polarization Streams (SAPS) are one of the most outstanding phenomena in the subauroral ionosphere. Its position can be a measure for nowcasting the intensity/size of the global ionospheric convection. In the current study, the latitudinal distribution of SAPS is discussed based on the over ten years of observation achieved by the SuperDARN Hokkaido Pair of radars, which are located at the lowest geomagnetic latitudes among the SuperDARN radars. Previous statistical studies showed that the latitudinal position of the SAPS structure could be predicted on average as a function of magnetic local time and the Dst geomagnetic index. The multi-event study shows, however, that the latitude of the SAPS structure does not always follow the empirical relationship, which could determine the latitude of the SAPS structure as a function of the Dst index and magnetic local time. For example, a detailed analysis of the 8 Sep 2017 event indicates that the SAPS position is located at a significantly lower geomagnetic latitude than the statistically expected position, even if the magnetic local time and Dst geomagnetic activity effects are considered. Possible reasons for such an unusual position, including the history of the IMF and the solar wind parameters and occurrence of substorms, are investigated.

How to cite: Nishitani, N. and Hori, T.: Attempt to nowcast the latitudinal position of the SAPS structure using the SuperDARN Hokkaido Pair of radars, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11533, https://doi.org/10.5194/egusphere-egu23-11533, 2023.

EGU23-11740 | Orals | ST4.2 | Highlight

Developing geomagnetically induced current forecasting capability across Europe 

Gemma Richardson, Ciarán Beggan, Guanren Wang, Ewelina Florczak, and Ellen Clarke

Space weather poses a hazard to grounded electrical infrastructure such as power transmission networks, through the induction of geomagnetically induced currents (GIC). Modelling GIC in real-time, as well as historical events and extreme event scenarios is of great importance for understanding and mitigating the effects on power networks. We have constructed a model of the interconnected European power networks using open-source data, to provide estimates of GIC across the whole continent, with the goal of creating a real-time operational warning system.

In recent years there have also been improvements in forecasting the ground geomagnetic field from L1 solar wind measurements using magnetohydrodynamic (MHD) models, and the development of models which forecast the solar wind itself days ahead of time. As part of the EUHFORIA2.0 Horizon 2020 project we have coupled models for the full Sun-to-Earth system to generate forecasts of geomagnetic fields, geoelectric fields and ultimately GIC across Europe.

How to cite: Richardson, G., Beggan, C., Wang, G., Florczak, E., and Clarke, E.: Developing geomagnetically induced current forecasting capability across Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11740, https://doi.org/10.5194/egusphere-egu23-11740, 2023.

EGU23-11771 | Orals | ST4.2 | Highlight

From research to the operation of solar wind forecasting with SafeSpace Helio1D: lessons learned and ways forward 

Rungployphan Kieokaew, Rui Pinto, Mikel Indurain, Evangelia Samara, Benoit Lavraud, Antoine Brunet, Stefaan Poedts, Vincent Génot, Alexis Rouillard, Sébastien Bourdarie, and Ioannis Daglis

Our current capability of space weather prediction in the Earth's radiation belts is limited to only an hour in advance using solar wind monitoring at the Lagrangian L1 point. To mitigate the impacts of space weather on telecommunication satellites, advancing the lead time of the prediction is a critical task. We develop a prototype pipeline called "Helio1D" to forecast ambient solar wind conditions (speed, density, temperature, tangential magnetic field) at L1 with a lead time of 4 days. This pipeline predicts Corotating Interaction Regions (CIRs) in which their compressed stream interfaces and high-speed streams can increase high-energy fluxes in the radiation belts. The Helio1D pipeline connects the Multi-VP model, which provides real-time solar wind emergence at 0.14 AU, and the 1D MHD model. Using the long-term data from Multi-VP, we benchmark the Helio1D pipeline for solar wind speed against the observation data in 2004 - 2013 and 2017 - 2018. We developed a framework based on the Fast Dynamic Time Warping technique that allows us to continuously compare time-series outputs containing CIRs to observations to measure the pipeline's performance. In particular, we use this framework to calibrate and improve the pipeline's performance for operational forecasting. Since the 1D MHD model is computationally inexpensive, we provide daily ensemble forecasting of 21 members, including several targets around the Earth to account for the uncertainties. This pipeline can be used to feed real-time, daily solar wind forecasting to predict the dynamics of the inner magnetosphere and the radiation belts. In this presentation, we will share the lessons from this research-to-operation project and discuss ways to effectively implement operational space weather pipelines.  

How to cite: Kieokaew, R., Pinto, R., Indurain, M., Samara, E., Lavraud, B., Brunet, A., Poedts, S., Génot, V., Rouillard, A., Bourdarie, S., and Daglis, I.: From research to the operation of solar wind forecasting with SafeSpace Helio1D: lessons learned and ways forward, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11771, https://doi.org/10.5194/egusphere-egu23-11771, 2023.

EGU23-14687 | ECS | Orals | ST4.2

Satellite Data Intercalibrationof Ring Current Observations 

Marina García Peñaranda, Yuri Shprits, and Angelica M. Castillo Tibocha

The Earth’s ring current is a complex, dynamic system that plays an important role in geomagnetic storms. This ring-shaped current environment changes its structure and intensity on different time scales as a result from the incoming solar wind.  The different particle populations display very different behaviors, making it extremely hard to develop physics-based forecasting models for this environment.

Satellite data provides electron point measurements that can be used to study the different physical processes occurring in the Earth’s magnetospheric ring current. However, in order to fully understand the particle dynamics and injection processes in this region, high temporal and spatial data resolutions are required.

We tackle this issue by using a combination of electron-flux observations from different satellite missions and instruments in order to improve the global resolution of this dynamic environment by intercalibrating POES, GOES, THEMIS and RBSP. To illustrate a use for this combined data set, we present a global reconstruction of the ring current population and a comparison of the observed electron flux environment with a re-analysis of the ring current region.

How to cite: García Peñaranda, M., Shprits, Y., and M. Castillo Tibocha, A.: Satellite Data Intercalibrationof Ring Current Observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14687, https://doi.org/10.5194/egusphere-egu23-14687, 2023.

EGU23-15816 | Orals | ST4.2

An update on the UK ground level neutron monitor implementation phase. 

Michael Aspinall, Jim Wild, Stephen Croft, Malcolm Joyce, Tilly Alton, Lee Packer, Steve Bradnam, Tony Turner, and Cory Binnersley

The global network of neutron monitors comprises predominantly of the monitor standardised by Carmichael in 1964, the NM-64.  The design of these existing monitors and their instrumentation have changed very little over the last sixty years.  For example, their neutron detectors rely on gas filled proportional counters that are either filled with highly toxic boron trifluoride (BF3) or helium-3 (3He) in an arrangement not optimised for this detector type.  We have designed a new neutron monitor optimised for fully modernised, 1” diameter, gas-filled 3He detectors.  Our new design is optimised for cost savings, compactness and efficient use of 3He.  Benchmarked against a 6-NM-64, our design has a 71% smaller footprint, 83% smaller volume, and is 55% lighter.  It is estimated to be ~50% cheaper, excluding cost reductions associated with the shipping, installation, housing, maintenance and operation of a more compact instrument.  It is suited for unattended operation in relatively remote locations and designed to produce comparable results to a 6-counter NM-64 typically used in the existing global network.  We provide a progress update and latest validation results relating to the implementation of the new design at the UK Metrological Office’s Camborne observatory near Cornwall.  Funded by UK Research & Innovation (UKRI), this research is part of the Space Weather Instrumentation, Measurement, Modelling and Risk (SWIMMR) programme.

How to cite: Aspinall, M., Wild, J., Croft, S., Joyce, M., Alton, T., Packer, L., Bradnam, S., Turner, T., and Binnersley, C.: An update on the UK ground level neutron monitor implementation phase., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15816, https://doi.org/10.5194/egusphere-egu23-15816, 2023.

EGU23-16351 | Orals | ST4.2 | Highlight

Pre-operational Space Weather Services at the DLR Institute for Solar-Terrestrial Physics 

Martin Kriegel, Paul David, Youssef Tagargouste, Dmytro Vasylyev, David Wenzel, and Jens Berdermann

In times of highly precise and increasingly autonomous GNSS applications, the influence of space weather on their system performance is increasingly becoming the focus of current research and development. The complex monitoring and research of space weather in its variety of phenomena and with its effects, for example in satellite technology, aerospace, telecommunications and navigation, is an increasingly important mission.

The DLR Institute for Solar-Terrestrial Physics in Neustrelitz is investigating the influence of space weather on both critical systems and services such as GNSS or RF communications, as well as ground- and space-based infrastructures such as power grids or satellites. Of outstanding importance is the efficient implementation of the interfacing between the increasing scientific expertise and the most diverse user requirements from the national and international public and private sectors, academia and industry.

As an essential core component of this interface, the working group "Pre-operational Services" develops and operates the "Ionosphere Monitoring and Prediction Center (IMPC)" in cooperation with the "German Remote Sensing Data Center" of the DLR. With its special combination of scientific know-how on GNSS based remote sensing and modelling of the ionopshere, instrumentation (e.g. high rate GNSS receiver network, Global Ionospheric Flare Detection System (GIFDS), Callisto) and the use of state-of-the-art data processing technologies, the IMPC contributes significantly to monitoring the impact of space weather on today's technologies in near-real time and to avoiding or reducing it through the application of a wide range of products and services.
This contributionwill present IMPC's pre-operational services and their incorporation into relevant national and international networks (e.g. NOAA-SWPC RTSW, ESA S2P, PECASUS). Furthermore, the unique instrumentation, applied technology approaches and already developed and planned products and services will be presented.

How to cite: Kriegel, M., David, P., Tagargouste, Y., Vasylyev, D., Wenzel, D., and Berdermann, J.: Pre-operational Space Weather Services at the DLR Institute for Solar-Terrestrial Physics, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16351, https://doi.org/10.5194/egusphere-egu23-16351, 2023.

EGU23-16532 | Orals | ST4.2 | Highlight

Predicting Outer Van Allen Belt Dynamics with the Prototype SafeSpace Service 

Ioannis A. Daglis and Afroditi Nasi and the SafeSpace Team

The European SafeSpace project has implemented a synergistical approach to improve space weather forecasting capabilities from the current lead times of a few hours to 2-4 days. We have combined the solar wind acceleration model MULTI-VP with the heliospheric propagation models Helio1D and EUHFORIA to compute the evolution of the solar wind from the surface of the Sun to the Earth orbit. The forecasted solar wind conditions are then fed into the ONERA Geoffectiveness Neural Network, to forecast the level of geomagnetic activity with the Kp index as the chosen proxy. The Kp index is used as the input parameter for the IASB plasmasphere model and for the Salammbô radiation belts code. The plasma density is used to estimate VLF wave amplitude and then VLF diffusion coefficients, while the predicted solar wind parameters are used to estimate the ULF diffusion coefficients through the NKUA EMERALD model. Plasmaspheric density and VLF/ULF diffusion coefficients are used by the Salammbô radiation belts code to deliver a detailed flux map of energetic electrons. Finally, particle radiation indicators are also provided as a prototype space weather service of use to spacecraft operators and space industry, accessible at http://www.safespace-service.eu. The performance of the prototype service has been evaluated in collaboration with space industry stakeholders. The work leading to this paper has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870437 for the SafeSpace (Radiation Belt Environmental Indicators for the Safety of Space Assets) project.

How to cite: Daglis, I. A. and Nasi, A. and the SafeSpace Team: Predicting Outer Van Allen Belt Dynamics with the Prototype SafeSpace Service, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16532, https://doi.org/10.5194/egusphere-egu23-16532, 2023.

EGU23-17050 | Orals | ST4.2 | Highlight

Forecasting and analysis of solar particle radiation storms: A state-of-the-art solution provided by the HESPERIA SEP Real-Time Forecasting products 

Olga Malandraki, Michalis Karavolos, Dimitris Kokkinis, Nikolaos Milas, Norma Crosby, Mark Dierckxsens, Marlon Nunez, and Patrick Kuehl

For human spaceflight beyond low-Earth orbit, particularly outside the Earth's magnetosphere, it is essential to provide accurate predictions of Solar Energetic Particle (SEP) occurrences. SEPs with energies ranging from tens of keV to a few GeV, are a significant component in the description of the space environment. SEP events feature a wide range of energy spectrum profiles and can last for a few hours to several days or even weeks. As well as posing a threat to modern technology that heavily relies on spacecraft and posing a major radiation hazard to astronauts, they can also constitute a threat to avionics and commercial aircraft in extreme circumstances. The SEP Real-Time Forecasting HESPERIA products have been developed under the HESPERIA H2020 project (Project Coordinator: Dr. Olga Malandraki) and since 2015 provide significant results concerning the prediction of SEP events. More specifically, the HESPERIA UMASEP-500 product makes real-time predictions of the occurrence of >500 MeV proton events and Ground Level Enhancement (GLE) events based on the analysis of soft X-ray and high energy differential proton fluxes measured by the GOES satellite network. The HESPERIA REleASE product, based on the Relativistic Electron Alert System for Exploration (REleASE) forecasting scheme, generates 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. Lastly, the HESPERIA REleASE Alert is a notification system based on the forecasts produced by the HESPERIA REleASE product and informs about the expected radiation impact in real-time using an illustration and a distribution system for registered users. The real-time and highly accurate forecasts as well as the timely performance offered by the HESPERIA products have attracted the attention of various space organizations (e.g. NASA/CCMC, SRAG) and also led to the selection and integration of them into the ESA Space Weather (SWE) Service Network (https://swe.ssa.esa.int/noa-hesperia-federated). The integration process, based on the strict guidelines posed by ESA, has determined the current form of the HESPERIA products using state-of-the-art technologies and paradigms concerning both the graphical user interface and the mechanisms to provide the forecasting results to the end users with a high-quality experience. We will present the HESPERIA products as provided through the ESA SWE Service Network under the Space Radiation Expert Service Centre (R-ESC). Moreover, solar radiation storms successfully predicted during Solar cycle 25 will also be presented and discussed. (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: Malandraki, O., Karavolos, M., Kokkinis, D., Milas, N., Crosby, N., Dierckxsens, M., Nunez, M., and Kuehl, P.: Forecasting and analysis of solar particle radiation storms: A state-of-the-art solution provided by the HESPERIA SEP Real-Time Forecasting products, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17050, https://doi.org/10.5194/egusphere-egu23-17050, 2023.

EGU23-17272 | Orals | ST4.2

STEP-F and SphinX particle and X-ray detector as sensitive actuators for radiation environment of near-Earth space 

Oleksiy Dudnik, Oleksandr Yakovlev, Mirosław Kowaliński, Piotr Podgórski, and Janusz Sylwester

The state of geomagnetic environment as observed at the ground level is characterized by numerous indices, derived from measurements from numerous magnetic observatories scattered over many longitudes and latitudes. In support, patrol measurements of geomagnetic field components are carried out in near-Earth space using onboard magnetometers that constantly cross geomagnetic field thanks to the orbital motion of the spacecraft. In the same way, high-energy charged particle fluxes trapped by the Earth's magnetic field are monitored along the satellite orbit. In the geomagnetic radiation belts’ environment, the distribution of proton fluxes is mostly less variable, while electron fluxes experience strong variations associated even with weak fluctuations of well-known indices: mid-latitude Kp, and equatorial Dst (related to weak geomagnetic storms). During very strong geomagnetic storms an additional electron radiation belt appears in a slot between outer and inner Van Allen belts. However, even during the period of minimum solar activity when small variations of the geomagnetic field prevail, noticeable changes in electron fluxes are being recorded, including recently discovered presence of additional electron radiation belt at by L=1.6 McIllwain surface.

In present research, we used data collected by the two instruments placed next to each other aboard the low Earth (h ≈ 550 km) near polar (φ ≈ 82.50) orbit CORONAS-Photon satellite. We studied responses of the Satellite Telescope of Electrons and Protons (STEP-F) and the Solar photometer in X-rays (SphinX) in May 2009, a period which was characterized by a very weak solar and geomagnetic activity. As geomagnetic indicators we used Kp, Dst-, and SYM-H indices. For SphinX measurements, we extracted 5-second data in the highest energy bin sensitive to detection of charged particles. For STEP-F we analysed 2-second data records in the upper silicon position-sensitive detector while the satellite crossed all three electron radiation belts present in the magnetosphere. We demonstrate variable, belt-dependent high amplitude responses due to energetic electron presence in all three belts as well as specific time-dependent features due to presence of directed particle streams. Examples will be provided and discussed.

How to cite: Dudnik, O., Yakovlev, O., Kowaliński, M., Podgórski, P., and Sylwester, J.: STEP-F and SphinX particle and X-ray detector as sensitive actuators for radiation environment of near-Earth space, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17272, https://doi.org/10.5194/egusphere-egu23-17272, 2023.

EGU23-185 | Orals | GI6.8

Space weather during extreme SEPs: new assessment of worst case scenario 

Alexander Mishev, Sanja Panovska, and Ilya Usoskin

An important topic in the field of space physics is the quantification of the cosmic-ray-induced effects in the atmosphere and the corresponding space weather effects. Space weather effects, specifically the exposure to radiation at aviation altitudes, represent an important threat. Here, we focus on a specific class of events due to solar energetic particles (SEPs), viz. events that can be registered at ground level: ground-level enhancements and more particularly extreme events with cosmogenic imprints,i.e. that have been registered by 14C records.

Naturally, for assessment of space weather effects during extreme SEP events, it is necessary to possess precise information on their spectra. Here we present results and application of an analysis of SEPs using neutron monitor (NM) records, that is derivation of their spectra, and application of numerical models. Using reconstructed spectra during the strongest directly recorded event, that is GLE # 5, occurred on 23 February 1956, and employing a convenient rescaling,  we assessed the space weather effect during the strongest indirectly reconstructed historical extreme SEP event, that is, 774 AD. Subseqeuntly, employing a state-of-the-art reconstruction of the magnetic field we study the worst-case scenario representing a combination of a geomagnetic excursion, that is the Laschamp excursion ca. 42 kyr ago and a 774 AD-like event. The possible implications are discussed.

How to cite: Mishev, A., Panovska, S., and Usoskin, I.: Space weather during extreme SEPs: new assessment of worst case scenario, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-185, https://doi.org/10.5194/egusphere-egu23-185, 2023.

EGU23-287 | ECS | Orals | GI6.8

A New Open-Source Geomagnetosphere Propagation Tool (OTSO) and its Applications 

Nicholas Larsen, Alexander Mishev, and Ilya Usoskin

We present a new open-source tool for magnetospheric computations, that is modelling of cosmic ray propagation in the geomagnetosphere, named "Oulu - Open-source geomagneToSphere prOpagation tool" (OTSO). A tool of this nature is required to interpret experiments and study phenomena within the cosmic ray research field.  Here, we demonstrate several applications of OTSO, namely the computation of asymptotic directions of selected cosmic ray stations, effective rigidity cut-off across the globe at various conditions within the design, and general properties, including the magnetospheric models employed. OTSO was applied to the investigation of several ground-level enhancement events after which comparison and validation of OTSO with older widely used tools such as MAGNETOCOSMICS was performed, and good agreement was achieved. The necessary background for the analysis of two notable ground-level enhancements was produced using OTSO and their spectral and angular characteristics show good agreement with prior studies and spacecraft data. This validation of OTSO's current abilities reveals its usefulness to the cosmic ray research field and its open-source nature further allows for the tool to be developed beyond its current capabilities by users to meet the needs of the research community.

How to cite: Larsen, N., Mishev, A., and Usoskin, I.: A New Open-Source Geomagnetosphere Propagation Tool (OTSO) and its Applications, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-287, https://doi.org/10.5194/egusphere-egu23-287, 2023.

EGU23-3095 | Posters on site | GI6.8

Effects of heterogeneous soil moisture distributions in cosmic-ray neutron sensing - the case of irrigation monitoring 

Heye Bogena, Cosimo Brogi, Markus Köhli, Harrie-Jan Hendricks Franssen, Olga Dombrowski, and Johan Alexander Huisman

Soil moisture (SM) sensors are widely used to monitor soil water dynamics and support irrigation management with the aim of achieving better yields while reducing water consumption. Unfortunately, due to the small measuring volume of point-scale sensors, their soil moisture readings are often not representative for heterogeneous agricultural fields. Therefore, in such cases, sensors with larger sensing volume are needed to address spatially variable SM. A suitable technique is the cosmic ray neutron sensor (CRNS) as it integrates SM over a large volume with a radius of ~130-210 m and a penetration depth of ~15-85 cm. The CRNS method is based on the inverse relationship between measured environmental neutron density and the presence of hydrogen pools (e.g., SM) in the instrument surroundings. However, the ability of CRNS to accurately monitor areas with complex SM heterogeneities (e.g., small irrigated fields) and the influence of detector design were not yet investigated. In this study, we used the neutron transport model URANOS to simulate the effect of SM variations on a CRNS placed in the centre of squared irrigated fields (0.5 to 8 ha dimensions). For this, SM in the irrigated field and in the surrounding was altered between 0.05 and 0.50 cm3 cm-3 (500 simulations in total). In addition, we investigated the effect of employing high-density polyethylene (HDPE) moderators with different thickness (5 to 35 mm) as well as a 25 mm HDPE moderator with an additional gadolinium oxide thermal shielding. Results showed that, in heterogeneous SM scenarios, the 2 e-folding lengths footprint (R86) can become smaller or larger than what previous studies showed in homogeneous SM distributions. In addition, a thin HDPE moderator will result in relatively smaller R86 whereas thicker moderators and the addition of a thermal shielding will result in relatively larger R86. However, we found that a relatively small footprint is not directly related to a better monitoring of SM nearby the instrument. In fact, in all the investigated field dimensions, the 25mm HDPE moderator with gadolinium shielding showed the largest values of R86 but also the largest variations of detected neutrons with changing SM. In addition, such moderator showed the highest chances of detecting irrigation events that increase SM by 0.05 or 0.10 cm3 cm-3 in the irrigated area. Generally, detection was uncertain only for SM variations of 0.05 cm3 cm-3 in fields of 0.5 ha when initial SM was 0.02 cm3 cm-3 or higher. Although the results of this study suggest the feasibility of monitoring and informing irrigation with CRNS, we found that SM variations outside the irrigated field have a considerable influence on CRNS measurements. Especially in fields of 0.5 and 1 ha dimension, it can be impossible to distinguish whether a relative change in detected neutrons is due to irrigation or to SM variations in the surroundings. These results are relevant for irrigation monitoring and the combination of neutron transport simulations and real-world installations has the potential to establish CRNS as a decision support system for irrigation management.

How to cite: Bogena, H., Brogi, C., Köhli, M., Hendricks Franssen, H.-J., Dombrowski, O., and Huisman, J. A.: Effects of heterogeneous soil moisture distributions in cosmic-ray neutron sensing - the case of irrigation monitoring, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3095, https://doi.org/10.5194/egusphere-egu23-3095, 2023.

EGU23-4506 | Orals | GI6.8

ORCA (Observatorio de Rayos Cósmicos Antártico), current status and future perspectives 

Juan José Blanco, Juan Ignacio García Tejedor, Sindulfo Ayuso de Gregorio, Óscar García Población, Alejandro López-Comazzi, Diego Sanz Martín, Ivan Vrublevskyy, Laura Gonzalvo Ballano, and Alberto Regadío

ORCA (2.37 GV) is a suit of two neutron monitors and a muon telescope. It was installed at Juan Carlos I Antarctic Base on January 2019 being in operation since. Because the low level of the solar activity, only a few of solar events have been detected. The GLE 73 and three Forbush decreases. A new ORCA like detector (ICaRO, 11.5 GV) is being installed at 2200 m a.s.l in Izaña Atmospheric Observatory (Tenerife Island, Spain). On the other hand, CaLMa neutron monitor (6.95 GV) will be updated with a muon telescope made by eight 1 m2 scintillators arranged in two layers of four scintillators at some point during the next two years. These three detector will measure muons and neutrons from cosmic ray interaction with atmosphere at three different locations allowing to study the solar activity from a new perspective

How to cite: Blanco, J. J., García Tejedor, J. I., Ayuso de Gregorio, S., García Población, Ó., López-Comazzi, A., Sanz Martín, D., Vrublevskyy, I., Gonzalvo Ballano, L., and Regadío, A.: ORCA (Observatorio de Rayos Cósmicos Antártico), current status and future perspectives, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4506, https://doi.org/10.5194/egusphere-egu23-4506, 2023.

EGU23-6045 | Posters on site | GI6.8

The concentration of cosmogenic radionuclide 7Be from the perspective of space weather and long-term trends in the stratospheric temperature and wind 

Kateřina Podolská, Michal Kozubek, Miroslav Hýža, and Tereza Šindelářová

Cosmogenic radionuclide Beryllium 7Be concentration is primarily determined by the solar activity level and space weather conditions. The 7Be is generated by cosmic ray reactions in the stratosphere and in the upper troposphere, binds to atmospheric aerosols and is transported horizontally and vertically by wind and gravity. The highest values of cosmic radiation are observed during the solar minima because, at that time the penetrability of the Earth’s and Sun magnetosphere is greatest.

The concentrations of the radionuclide 7Be are reliable indicators of various atmospheric processes. In our work, we try to contribute to better understanding of the dynamics of processes by associating them with long-term trends of stratospheric temperature dynamics. We investigate the coupling of concentrations of the cosmogenic radionuclide 7Be in the longitudinal view during the years 1986–2022 (time series of activity concentration of 7Be in aerosols evaluated by the corresponding activity in aerosols on a weekly basis at the National Radiation Protection Institute Monitoring Section in Prague) to space weather parameters (Kp planetary index, disturbance storm time Dst, proton density, proton flux), and stratospheric dynamics parameters (temperature, zonal component of wind, O3). On short timescales the intensity of cosmic radiation decreases by few percent in several days. On a longer timescale the intensity of galactic cosmic rays is strongly influenced by the degree of solar activity and by variations in the geomagnetic field. This corresponds with findings that the zonal wind climatology differences were largest in the decades of 2000–2010 than between others observed decades.

How to cite: Podolská, K., Kozubek, M., Hýža, M., and Šindelářová, T.: The concentration of cosmogenic radionuclide 7Be from the perspective of space weather and long-term trends in the stratospheric temperature and wind, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6045, https://doi.org/10.5194/egusphere-egu23-6045, 2023.

EGU23-6789 | Posters on site | GI6.8

Sensitivity of the Cosmic Ray Neutron Sensor (CRNS) to Seasonal Biomass Dynamics in Cherry and Olive Orchards 

Samir K. Al-Mashharawi, Marcel M. El Hajj, Kasper Johansen, Matthew F. McCabe, and Susan Steele-Dunne

Biomass estimation is important in many applications, such as carbon sequestration and precision agriculture. Developing a reliable method for biomass estimation from satellite, airborne and near-surface remote sensing sensors is an ongoing task due to the large uncertainty in current methods, which are often related to sensor limitations. Indeed, signals from optical sensors and synthetic aperture radar at high and medium frequencies suffer from saturation issues at high biomass levels. The Cosmic-Ray Neutron Sensor (CRNS) is a new non-invasive near-surface sensor used primarily to estimate soil water content (SWC), but it has also shown potential for retrieving other hydrological and environmental parameters such as biomass water equivalent and snow depth. The CRNS detects and counts the number of neutrons controlled by hydrogen atoms in the soil, air just above the ground, and vegetation. Biomass attenuates the intensity of cosmic ray neutrons, hence the ability to estimate biomass from a CRNS. Recent studies have used CRNS measurements to estimate biomass changes in crop areas and forest stands, while the use of CRNSs in orchards is limited. The objective of this study is to explore the potential of two CRNSs to estimate the biomass variation in irrigated cherry and olive tree orchards. The olive tree orchard is located in an arid region in northern Saudi Arabia (plantation density of 1667 trees/hectare) with an average tree height of 3 m and canopy diameter of 2 m. The cherry field is located in southern France (plantation density of 260 trees/hectare) with an average tree height of 3.5 m and canopy diameter of 5.5 m. Several soil moisture probes recording soil water content (SWC) at 15-min intervals at both sites were installed at different depths within the CRNS footprint. SWC measurements were used to assess the variations in the sensitivity of CRNS to soil moisture with increasing biomass. Tree parameters (height, canopy width, canopy length, leaf area index, and diameter at breast height) were measured in situ to estimate biomass using allometric equations. In addition, repetitive Light Detection and Ranging (LiDAR) scanning was performed over the cherry field to detect canopy volume changes over time. The results showed that the CRNS is sensitive to SWC variation, and this sensitivity is controlled by biomass evolution, indicating that CNRS measurements can also be used to estimate biomass. The sensitivity of CRNS neutron counts to SWC in the early season (before blooming) was twice as high as that during the mid- and late growing seasons (maximum leaf cover). The Cornish Pasdy model­, which models the measured neutron counts as a function of SWC and biomass contribution, was calibrated and then inverted to estimate the biomass in the cherry and olive tree orchards. 

How to cite: Al-Mashharawi, S. K., El Hajj, M. M., Johansen, K., McCabe, M. F., and Steele-Dunne, S.: Sensitivity of the Cosmic Ray Neutron Sensor (CRNS) to Seasonal Biomass Dynamics in Cherry and Olive Orchards, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6789, https://doi.org/10.5194/egusphere-egu23-6789, 2023.

EGU23-11071 | ECS | Posters on site | GI6.8

Updated heliospheric modulation potential of cosmic rays and station-specific scaling factors for 1964-2021 

Pauli Väisänen, Ilya Usoskin, Riikka Kähkönen, Sergey Koldobskiy, and Kalevi Mursula

Galactic cosmic rays (GCR) are energetic particles originating from galactic or extra-galactic sources. When they arrive inside our heliosphere, they are modulated by the magnetic irregularities in the solar wind flow from the Sun, deflecting and slowing down the GCR particles. The level of this modulation varies according to solar activity, especially the 11-year solar cycle. The heliospheric modulation potential, denoted by ϕ, describes the average energy loss of particle in MV and quantifies the level of modulation. It can be determined using ground-based neutron monitor (NM) measurements of GCRs by multiple stations. Here we use the most recent version of the NM yield function and a RMSE-minimization method to compute a new and more accurate version of the modulation potential ϕ and station-specific scaling factors κ, which can be used to scale the level of count rates to the theoretical NM count rate given by the model. The new version offers daily resolution of ϕ and can be conveniently updated with new measurements, stations, or updates to datasets whenever they might occur. The scaling factors and their variation can be used to scale the data for physical analyses or to identify outliers, errors or physical phenomena which do not match with the model.

How to cite: Väisänen, P., Usoskin, I., Kähkönen, R., Koldobskiy, S., and Mursula, K.: Updated heliospheric modulation potential of cosmic rays and station-specific scaling factors for 1964-2021, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11071, https://doi.org/10.5194/egusphere-egu23-11071, 2023.

EGU23-11326 | ECS | Posters on site | GI6.8

Monitoring soil moisture in the deeper vadose zone: A new approach using groundwater observation wells and cosmic ray neutrons 

Daniel Rasche, Jannis Weimar, Martin Schrön, Markus Köhli, Markus Morgner, Andreas Güntner, and Theresa Blume

Monitoring soil moisture at depths greater than one meter is generally challenging and often highly invasive as it requires opening large soil pits. As a result, this deeper vadose zone is often not monitored at all. On top of that, conventional soil moisture sensors usually have only a small measurement volume. On the other hand, soil moisture estimates derived from above-ground Cosmic-Ray Neutron Sensing (CRNS) are a representative average over an area of several hectares but only of the upper half meter of the soil. To this day, it is commonly believed that cosmic radiation cannot be used to monitor soil water content below this depth. As a consequence, large parts of the root-zone and deeper unsaturated zone have remained outside the observational window of the method. The estimation of soil moisture in greater depths typically requires additional invasive measurements, other active geophysical methods, or mathematical models which extrapolate surface soil moisture observations.

Against this background, we investigated the possibility of using passive detection of cosmogenic neutrons in existing monitoring infrastructure (e.g. groundwater wells). We hypothesized that this method provides a larger measurement volume than traditional techniques based on active neutron probes while requiring less safety restrictions.

Our neutron transport simulations demonstrated that this downhole-CRNS technique would be sensitive enough to detect changes of water content in depths down to 5 meters and above, depending on the temporal resolution of measurements. The simulations also revealed a large measurement radius of several tens of cm depending on the soil moisture content and soil bulk density.

From the theoretical results we derived a functional relationship between soil moisture and detectable neutrons and tested it in a groundwater observation well. Additional installations of supporting soil moisture sensors have been used to validate the model predictions as well as the neutron signals monitored by the CRNS detector. The study demonstrated the general applicability of downhole Cosmic-Ray Neutron Sensing for the estimation of soil moisture in greater depths and at temporal resolution of two days.

How to cite: Rasche, D., Weimar, J., Schrön, M., Köhli, M., Morgner, M., Güntner, A., and Blume, T.: Monitoring soil moisture in the deeper vadose zone: A new approach using groundwater observation wells and cosmic ray neutrons, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11326, https://doi.org/10.5194/egusphere-egu23-11326, 2023.

EGU23-11905 | Posters virtual | GI6.8

SEVAN European particle detector network for the atmospheric, solar and space weather studies 

Tigran Karapetyan, Ashot Chilingarian, and Balabek Sargsyan

Experiments during recent years with SEVAN detectors on mountain tops in Armenia, Slovakia, and Bulgaria reveal the broad potential of SEVAN detectors; The SEVAN detector on Lomnicky Stit (Slovakia) measured the largest thunderstorm ground enhancements (TGE), with particle fluxes exceeding the background 100-times. With muon and gamma ray fluxes, the maximum values of the potential difference in thunderclouds were measured, equal to 350 MV at Mt. Aragats, and 500 MV at the sharp peak of Lomnicky Stit. In Nov 2019, SEVAN detectors were installed at DESY (Hamburg and Zeuthen sites). Fluxes of electrons, photons, and muons and weather parameters are continuously monitored at all sites (at different latitudes, longitudes, and altitudes). To fully exploit the scientific potential of the SEVAN detectors, in 2023 is planned to install a new detector in the Umwelt-Forschungs-Station (UFS, Schneefernerhaus, 2650 m asl) near the top of the Zugspitze (2962 m), a site with a long history of atmospheric research. The new SEVAN module will be compact (SEVAN-light), and will enable the energy spectra measurements in the range from 0.3 to 50 MeV, allowing unambiguously separating Radon progeny gamma radiation from runaway electron-photon avalanches.

How to cite: Karapetyan, T., Chilingarian, A., and Sargsyan, B.: SEVAN European particle detector network for the atmospheric, solar and space weather studies, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11905, https://doi.org/10.5194/egusphere-egu23-11905, 2023.

Neutron monitor counting rates show, among others, a  $\sim$ 1.6--2.2-year period. This period has been associated with a solar origin affecting the cosmic ray propagation conditions through the heliosphere. The duration of this period varies from one Solar Cycle to another.
\cite{Comazzi_Blanco_2022} found the duration of the $\sim$ 1.6--2.2-year period ($\tau$) is linearly related to the averaged sunspot number ($SSN_a$) in each Solar Cycle.
In this piece of research, we have analyzed this relationship. This equation shows that shorter $\sim$1.6--2.2-year periods occur during stronger cycles when $SSN_a$ is higher. Drawing on this relationship given by $SSN_a = (-130 \pm 10) \: \tau + (330 \pm 30)$, we computed $\tau$ for the cycles previous to the existence of neutron monitors (Solar Cycles 7--19). 
By means of the Huancayo neutron monitor spectrum we checked the validity of this equation along the Solar Cycle 19. 
Once the previous relationship is checked, $\tau$ for the current Solar Cycle 25 is computed giving $\sim$ 2.22 years.

An internal mechanism of the solar dynamo called Rossby waves could produce these variations in the solar magnetic field  and, indirectly, in neutron monitor counting rates.
The harmonic of fast Rossby waves with $m=1$ and $n=8$ fit with the detected periodicity and the variation of the solar magnetic field strength from weaker to stronger Solar Cycles could explain the different periods detected in each cycle.
Finally, a solar magnetic field strength of $\sim$ 7--25 kG in the tachocline have been estimated based on the detected periodicities using the dispersion relation for fast Rossby waves. 

How to cite: López-Comazzi, A. and Blanco-Ávalos, J. J.: Study of the relationship between Sunspot number and the duration of the $\sim$1.6--2.2-year period in neutron monitor counting rates, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11981, https://doi.org/10.5194/egusphere-egu23-11981, 2023.

EGU23-12576 | ECS | Posters on site | GI6.8

Cosmic rays on snow: A combined analysis of fractional snow cover derived from Sentinel-2, MODIS and Cosmic Ray Neutron Sensors across Europe 

Nora Krebs, Paul Schattan, Sascha Oswald, Martin Schrön, Martin Rutzinger, and Johann Stötter

Epithermal neutrons from cosmic ray showers are slowed by hydrogen atoms in snow. The drop in the fast neutron abundance in the atmosphere can be measured with above-ground Cosmic Ray Neutron Sensing (CRNS), allowing for an estimation of the Snow Water Equivalent (SWE). SWE is an important variable that has a substantial role in hydrological modelling and forecasts. However, up to now, SWE is conventionally measured at point-scale, which holds only little information about the average SWE in areas of heterogeneous terrain and where snow drift is a predominant process. CRNS offers the prospect of closing this gap by sensing neutrons within a footprint of 10–20 hectares. Currently, further investigations are needed to reduce the uncertainties in the signal conversion from neutron counts to SWE. In this study, we compare the daily signals of 65 CRNS stations across Europe with the corresponding Fractional Snow Cover (FSC) products from Sentinel-2 and MODIS (Moderate-resolution Imaging Spectroradiometer) with a 20 m and 500 m spatial resolution, respectively. By analysing the FSC products, we were able to identify characteristic ranges of neutron counts at snow presence (winter signals) and absence (summer signals). Comparing these ranges and their overlap among stations, we were able to distinguish typical signal properties of lowland, pre-Alpine and Alpine sites. We found that altitude-related properties, such as soil and vegetation characteristics govern the general neutron level at the study sites. Snowfall typically leads to a major drop in the neutron count rate that is superimposed on the summer neutron count level. High-altitude stations are generally characterized by low ranges of count rates in summer and by high ranges in winter, while low-altitude stations show a reversed trend. Our results demonstrate that the suitability of a station for SWE measurements with CRNS depends highly on the site-specific hydrogen pool fluctuations that can be linked to altitude. Especially in heterogeneous mountain terrain with low soil formation, the advantages of CRNS come into play and can provide a spatial average of SWE with low uncertainties.

How to cite: Krebs, N., Schattan, P., Oswald, S., Schrön, M., Rutzinger, M., and Stötter, J.: Cosmic rays on snow: A combined analysis of fractional snow cover derived from Sentinel-2, MODIS and Cosmic Ray Neutron Sensors across Europe, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12576, https://doi.org/10.5194/egusphere-egu23-12576, 2023.