ST2.3 | Global magnetospheric dynamics in simulations and observations
EDI
Global magnetospheric dynamics in simulations and observations
Convener: Andrey Samsonov | Co-conveners: Yulia Bogdanova, Yann Pfau-KempfECSECS, David Sibeck, C.-Philippe Escoubet
Orals
| Tue, 25 Apr, 16:15–18:00 (CEST)
 
Room L1, Wed, 26 Apr, 08:30–10:15 (CEST)
 
Room L1
Posters on site
| Attendance Thu, 27 Apr, 10:45–12:30 (CEST)
 
Hall X4
Posters virtual
| Attendance Thu, 27 Apr, 10:45–12:30 (CEST)
 
vHall ST/PS
Orals |
Tue, 16:15
Posters on site |
Thu, 10:45
Posters virtual
Thu, 10:45
Large-scale dynamic processes in different magnetospheric regions, e.g., at the magnetopause, in the dayside magnetosphere, magnetotail, ring current, plasmasphere, and ionosphere, are closely interconnected therefore the magnetosphere should be considered as a global system. The state of the magnetosphere is controlled mainly by solar wind conditions. The interplanetary magnetic field (IMF) and solar wind plasma parameters control the energy input into the magnetosphere. Magnetic reconnection at the dayside magnetopause and in the tail current layer regulates energy transfer through the magnetosphere. Changes in the solar wind dynamic pressure and IMF move the magnetopause, causing global magnetospheric expansions and contractions. Variations in the solar wind velocity and IMF direction may also displace the magnetotail. Magnetic reconnection in the magnetotail injects thermal and energetic particles into the inner magnetosphere and downward along magnetic field lines into the ionosphere. On the other hand, the polar wind from the upper atmosphere may influence the nightside reconnection rate. Global magnetospheric dynamics can be studied by means of numerical simulations (MHD or kinetic), using empirical and semi-empirical models, or with the help of multipoint in situ spacecraft observations. Arrays of ground-based observatories and a fleet of various space missions can image magnetospheric and ionospheric phenomena globally, providing crucial information concerning the positions and dynamics of the magnetospheric plasma boundaries and the global distribution of ionospheric currents, convective flows, and particle precipitation. Past and future global imaging missions (e.g., TWINS, LEXI, SMILE) can complete this picture providing large-scale snapshots of some geospace regions. Accurate modelling of global magnetospheric processes is an essential condition for successful space weather predictions. We welcome any work presenting results on the global dynamics of the Earth’s magnetosphere as well as the magnetospheres of other planets.

Orals: Tue, 25 Apr | Room L1

Chairpersons: Andrey Samsonov, Yulia Bogdanova
16:15–16:20
5-minute convener introduction
16:20–16:30
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EGU23-9888
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ST2.3
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On-site presentation
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.

16:30–16:40
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EGU23-3924
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ST2.3
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On-site presentation
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.

16:40–16:50
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EGU23-3225
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ST2.3
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Highlight
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On-site presentation
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.

16:50–17:00
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EGU23-1863
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ST2.3
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ECS
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On-site presentation
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.

17:00–17:10
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EGU23-7399
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ST2.3
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ECS
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On-site presentation
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.

17:10–17:20
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EGU23-7204
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ST2.3
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On-site presentation
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.

17:20–17:30
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EGU23-6104
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ST2.3
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ECS
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Highlight
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On-site presentation
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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.

17:30–17:40
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EGU23-2354
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ST2.3
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ECS
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Highlight
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On-site presentation
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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.

17:40–17:50
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EGU23-16454
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ST2.3
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ECS
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Highlight
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On-site presentation
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.

17:50–18:00
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EGU23-1978
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ST2.3
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On-site presentation
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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.

Orals: Wed, 26 Apr | Room L1

Chairpersons: C.-Philippe Escoubet, David Sibeck, Yann Pfau-Kempf
08:30–08:40
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EGU23-9931
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ST2.3
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ECS
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On-site presentation
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.

08:40–08:50
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EGU23-5526
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ST2.3
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ECS
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solicited
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On-site presentation
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.

08:50–09:00
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EGU23-9418
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ST2.3
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On-site presentation
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.

09:00–09:10
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EGU23-8568
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ST2.3
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ECS
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On-site presentation
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.

09:10–09:20
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EGU23-8593
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On-site presentation
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.

09:20–09:30
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EGU23-1984
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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.

09:30–09:40
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EGU23-4032
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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.

09:40–09:50
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EGU23-11679
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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.

09:50–10:00
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EGU23-11423
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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.

10:00–10:10
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EGU23-16068
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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.

10:10–10:15
Discussion

Posters on site: Thu, 27 Apr, 10:45–12:30 | Hall X4

Chairpersons: Andrey Samsonov, Yulia Bogdanova
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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.

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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.

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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.

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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.

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EGU23-3234
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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.

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Interpretable Machine Learning Procedure Unravels Hidden Interplanetary Drivers of the Low Latitude Dayside Magnetopause 
Sheng Li and Yang-Yi Sun

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.

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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.

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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.

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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.

X4.248
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EGU23-10542
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ST2.3
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ECS
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.

X4.249
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EGU23-6613
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ST2.3
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ECS
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 J×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.

X4.250
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EGU23-10776
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ST2.3
The Effects of Magnetopause Motion and Substorm Stretching and Dipolarization on Magnetic Fields in the Inner Magnetosphere 
Syau-Yun Hsieh and David Sibeck

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.

X4.251
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EGU23-6875
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ST2.3
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ECS
|
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.

X4.252
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EGU23-1047
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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 RE 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.

X4.253
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EGU23-1196
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ST2.3
The Magnetospheric Driver of the Westward Traveling Surge: Plasma-Sheet Bubble Injections
(withdrawn)
Jian Yang, Dong Wei, Fei Zhang, Wenrui Wang, Weiqin Sun, Jun Cui, and Vassilis Angelopoulos
X4.254
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EGU23-6462
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ST2.3
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ECS
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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.

X4.255
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EGU23-7165
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ST2.3
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ECS
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.

X4.256
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EGU23-9233
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ST2.3
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ECS
Statistics of Magnetospheric Sawtooth Oscillations 
DiMarco Connor, 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: Connor, D., 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.

X4.257
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EGU23-12515
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ST2.3
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ECS
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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.

X4.258
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EGU23-17015
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ST2.3
Effect of solar wind dynamic pressure on the distribution of oxygen ions in the magnetosphere
(withdrawn)
Suiyan Fu, Quan Wang, Lun Xie, Qian Chen, and Hui Zhang
X4.259
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EGU23-7628
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ST2.3
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ECS
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.

X4.260
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EGU23-11389
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ST2.3
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ECS
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.

X4.261
|
EGU23-11674
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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.

X4.262
|
EGU23-13116
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ST2.3
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ECS
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.

X4.263
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EGU23-13581
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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.

Posters virtual: Thu, 27 Apr, 10:45–12:30 | vHall ST/PS

Chairpersons: Yann Pfau-Kempf, David Sibeck, C.-Philippe Escoubet
vSP.11
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EGU23-10258
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ST2.3
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ECS
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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.

vSP.12
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EGU23-3960
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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.