ST2.4 | Inner-magnetosphere Interactions and Coupling

ST2.4

EDI

The Earth's inner magnetosphere contains different charged particle populations, such as the Van Allen radiation belts, ring current particles, and plasmaspheric particles. Their energy range varies from eV to several MeV, and the interplay among the charged particles provides feedback mechanisms that couple all those populations together. Ring current particles can generate various waves, for example, EMIC waves and chorus waves, which play important roles in the dynamic evolution of the radiation belts through wave-particle interactions. Ring current electrons can be accelerated to relativistic radiation belt electrons. The plasmaspheric medium can also affect these processes. In addition, precipitation of ring current and radiation belt particles will influence the ionosphere, while up-flows of ionospheric particles can affect dynamics in the inner magnetosphere. Understanding these coupling processes is crucial.

While the dynamics of outer planets’ magnetospheres are driven by a unique combination of internal coupling processes, these systems have several fascinating similarities which make comparative studies particularly interesting. We invite a broad range of theoretical, modeling, and observational studies focusing on the dynamics of the inner magnetosphere of the Earth and outer planets, including the coupling of the inner magnetosphere and ionosphere and coupling between the solar wind disturbances and various magnetospheric processes. Contributions from all relevant fields, including theoretical studies, numerical modeling, and observations from satellite and ground-based missions are welcome. In particular, we encourage presentations using data from MMS, THEMIS, Van Allen Probes, Arase (ERG), Cluster, cube-sat missions, Juno, SuperDARN, magnetometer, optical imagers, IS-radars, and ground-based VLF measurements.

Co-organized by GI5/NP8
Convener: Dedong Wang | Co-conveners: Chao Yue, Hayley AllisonECSECS, Qiugang Zong
Orals
| Mon, 24 Apr, 08:30–12:25 (CEST)
 
Room 1.14
Posters on site
| Attendance Mon, 24 Apr, 14:00–15:45 (CEST)
 
Hall X4
Posters virtual
| Attendance Mon, 24 Apr, 14:00–15:45 (CEST)
 
vHall ST/PS
Orals |
Mon, 08:30
Mon, 14:00
Mon, 14:00

Orals: Mon, 24 Apr | Room 1.14

Chairpersons: Dedong Wang, Ondrej Santolik, Chao Yue
08:30–08:40
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EGU23-4064
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ST2.4
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ECS
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On-site presentation
Weiqin Sun, Jian Yang, Wenrui Wang, and Jun Cui

We present an analytic theory to demonstrate that electrons with an initially asymmetric spatial distribution would form an Archimedean spiral distribution in the inner magnetosphere. Such evolution is a result of the gradient/curvature drift, whose angular velocity decreases with radial distance. It has been known for a long time that spectrograms of energetic electrons in Earth's inner radiation belt exhibit time-varying organized peaks and valleys. Recent observations from Van Allen Probes have shown that such regular patterns are ubiquitous and are referred to as “zebra stripes”. Our theory can predict zebra stripes accurately. We also use the Rice Convection Model (RCM) to simulate zebra stripes. For the simplest situation with the dipolar magnetic field model, the analytic theory perfectly matches with the RCM simulation. In a realistic simulation, the RCM reproduces the time-dependent structures and evolution of the zebra stripes, which are in good consistency with Van Allen Probes observations.

How to cite: Sun, W., Yang, J., Wang, W., and Cui, J.: Archimedean Spiral Distribution of Electrons in Earth Inner Magnetosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4064, https://doi.org/10.5194/egusphere-egu23-4064, 2023.

08:40–08:50
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EGU23-9976
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ST2.4
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ECS
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On-site presentation
Ashley Greeley, Shrikanth Kanekal, and Quintin Schiller

Changes in pitch angle distributions can be a useful indicator of various changes in the radiation belts. Many methods of observing pitch angle distributions are qualitative. We present a method of studying pitch angle distributions that allows for a quantitative analysis of pitch angle distributions over time and energy channels, which allows for closer monitoring of spatial and temporal changes in the radiation belts. We use Van Allen Probes data from both spacecraft in fit pitch angle distributions with the form J0sinnα, tracking ‘n’ over time. We use this method of tracking pitch angle distributions to establish a connection between very localized wave particle interactions and particle scattering.

How to cite: Greeley, A., Kanekal, S., and Schiller, Q.: Using pitch angle index to quantify anisotropies in the outer radiation belt, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9976, https://doi.org/10.5194/egusphere-egu23-9976, 2023.

08:50–09:00
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EGU23-3482
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ST2.4
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On-site presentation
Yuri Shprits, Hayley Allison, Alexander Drozdov, and Dedong Wang

Novel analysis of phase space densities at multiple energies allows for differentiation between various acceleration mechanisms at ultra‐relativistic energies. This method allows us to trace how particles are being accelerated at different energies and show how long it takes for acceleration to reach particular energy. This method clearly demonstrates the importance of local acceleration and also demonstrates the importance of outward radial diffusion in transporting electrons to GEO.

Acceleration to such high energies occurs only when cold plasma in the trough region is extremely depleted, down to the values typical for the plasma sheet. We perform event and statistical analysis of these depletions and show that the ultra‐relativistic energies are reached for each such depletion that is accompanied by the intensification of ~2MeV. VERB‐2D simulations are then used to explain these observations. There is also a clear difference between the loss mechanisms at MeV and multi‐MeV energies due to EMIC waves that can very efficiently scatter ultra‐relativistic electrons but leave MeV electrons unaffected.

Modelling and observations clearly show that cold plasma has a controlling effect over the ultra‐ relativistic electrons that are 10^6‐10^7 times more energetic. We also present how the new understanding gained from the Van Allen Probes mission can be used to produce the most accurate data assimilative forecast. Under the recently funded EU Horizon 2020 Project Prediction of Adverse effects of Geomagnetic storms and Energetic Radiation (PAGER) we study how ensemble forecasting from the Sun can produce long‐term probabilistic forecasts of the radiation environment in the inner magnetosphere.

How to cite: Shprits, Y., Allison, H., Drozdov, A., and Wang, D.: The controlling effect of the cold plasma density over the acceleration and loss of ultra‐relativistic electrons, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3482, https://doi.org/10.5194/egusphere-egu23-3482, 2023.

09:00–09:10
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EGU23-17001
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ST2.4
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On-site presentation
Raluca Ilie, Jianghuai Liu, Michael Liemohn, and Joseph Borovky

We present a robust assessment of the formation and evolution of the cold H+ population produced via charge-exchange processes between ring current ions and exospheric neutral hydrogen in the inner magnetosphere, inferred via numerical simulations of the near-Earth plasma using a drift kinetic model of the ring current-plasmasphere system.

We evaluate the flow of mass and energy through the inner magnetospheric system and show that the production and evolution of the cold H+ population can be primarily driven by the plasma sheet conditions and dynamics and has the potential to reshape the plasmasphere and enhance the early-stage plasmaspheric refilling. We present evidence that the plasma sheet heavy ion composition is the primary controlling factor in the formation of the cold H+ via charge exchange with the geocorona, while the neutral density plays a much smaller role.

How to cite: Ilie, R., Liu, J., Liemohn, M., and Borovky, J.: A new mechanism for early time plasmaspheric refilling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17001, https://doi.org/10.5194/egusphere-egu23-17001, 2023.

09:10–09:20
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EGU23-5059
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ST2.4
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ECS
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On-site presentation
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Zhiyong Wu, Zhenpeng Su, Jerry Goldstein, Nigang Liu, Zhaoguo He, Huinan Zheng, and Yuming Wang

Whistler-mode hiss waves play an important role in the radiation belt electron depletion. Whether the hiss waves with significant differences in amplitude and propagation direction within the plasmaspheric core and plume are related to each other remains unclear. We here show that the plasmaspheric plume facilitates the energy conversion from energetic electrons to hiss waves and then guides hiss waves into the plasmaspheric core. Three ground and space missions captured the initial formation and subsequent rotation of the plasmaspheric plume in the noon-dusk-midnight sector following a strong substorm. The observed hiss waves in the nightside plasmaspheric plume and core propagated oppositely but highly correlated with each other at a time lag of 4-10 s. The linear instability of energetic electrons in the plasmaspheric plume qualitatively explains the frequency-dependence of hiss waves, and the ray-tracing modeling reproduces the propagation direction and timing of hiss waves.

How to cite: Wu, Z., Su, Z., Goldstein, J., Liu, N., He, Z., Zheng, H., and Wang, Y.: Nightside plasmaspheric plume-to-core migration of whistler-mode hiss waves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5059, https://doi.org/10.5194/egusphere-egu23-5059, 2023.

09:20–09:30
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EGU23-10180
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ST2.4
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On-site presentation
Solène Lejosne and Jay M. Albert

One of the key assumptions of radiation belt modeling based on a three-dimensional Fokker-Planck equation is that trapped particle fluxes do not depend on the drift phase (i.e., the azimuthal angle, or magnetic local time, MLT). It is usually considered that MLT-dependent structures (such as particle injection signatures and subsequent drift echoes) are rapidly smoothed out by drift phase mixing. Yet, the characteristic times for radiation belt drift phase mixing are not well known.

In this presentation, we show the existence of a naturally occurring phase mixing process in the presence of field fluctuations. This process complements the observational phase mixing due to the finite resolution of the measuring instrument.

We present a first quantification for the characteristic time of natural phase mixing and we discuss the implications in terms of radiation belt modeling.

How to cite: Lejosne, S. and Albert, J. M.: Characteristic Times for Radiation Belt Drift Phase Mixing, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10180, https://doi.org/10.5194/egusphere-egu23-10180, 2023.

09:30–09:40
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EGU23-10216
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ST2.4
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On-site presentation
Mostafa El Alaoui, Giovanni Lapenta, Liutauras Rusaitis, and Raymond Walker

Observations and magnetohydrodynamic simulations show that not all plasma injections from reconnection in the tail reach the inner magnetosphere to populate the ring current. We have used a self-consistent three-dimension particle-in-cell (PIC) simulation one way coupled to a global magnetohydrodynamic (MHD) simulation of the solar wind-magnetosphere-ionosphere system to investigate the population of the ring current during storm time substorms. This model includes a large fraction of the inner magnetosphere and the near-Earth tail. It allows us to study of the injection of particles from the tail and the interaction of the particles with plasma waves. The calculation begins with electrons and ions propagating earthward from the tail reconnection region. The particle distributions that enter the inner magnetosphere (R < 10 RE) from the magnetotail have a suprathermal component which acts as a seed population for the ring current. We imposed a steady southward IMF with a magnitude of 8 nT at the upstream boundary of the MHD simulation domain for more than three hours. The solar wind number density was 6 cm-3, the thermal pressure was 16 pPa, and the velocity was 530 km/s in the X direction toward Earth.  After we ran the MHD simulation, we chose an interval to examine during which there were several earthward flow channels and dipolarization fronts. Then, we used the output from this time to populate a large PIC simulation domain in the inner magnetosphere. In GSM coordinates, this domain extends over -22 RE <X < 12.5 RE, -13 RE < Y <13 RE, -5 RE < Z < 5 RE. The mass ratio was 256 with realistic ions and more massive electrons. In an initial simulation, we ran the code for 16,000 cycles and found that a ring current developed. We will discuss the reasons why some particles from the tail reach the inner magnetosphere, and some do not by examining how the particles are accelerated and lost.    

How to cite: El Alaoui, M., Lapenta, G., Rusaitis, L., and Walker, R.: Study of Ion Injection into the Inner Magnetosphere Using an Implicit Particle in Cell Simulation Driven by A Global MHD simulation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10216, https://doi.org/10.5194/egusphere-egu23-10216, 2023.

09:40–09:50
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EGU23-3445
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ST2.4
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On-site presentation
Kareem Sorathia, Adam Michael, Anthony Sciola, Shanshan Bao, Dong Lin, Slava Merkin, Sasha Ukhorskiy, Constanze Roedig, and Jeffrey Garretson

During geomagnetically active periods plasma is transported from the magnetotail into the inner magnetosphere to become the ring current. The transpot of plasma into the ring current occurs at different spatial and temporal scales, from global quasi-steady convection to bursty bulk flows (BBFs), with typical cross-tail extents of 1-3 Earth radii. During its enhancement, the ring current plays a critical role in magnetosphere-ionosphere coupling. Ring current ions build up plasma pressure in the inner magnetosphere and will drive field-aligned currents which must close in the ionosphere, while electrons will lead to diffuse precipitation and enhanced ionospheric conductance which shape the ionospheric path of current closure. Current closure in the ionosphere will couple to the thermospheric neutral population, via Joule heating, and alter the dynamics of the plasmasphere, via the penetration electric field in the inner magnetosphere. 

Understanding the relative role of convection at different spatial scales in both the buildup of the ring current and its broader effects on geospace coupling is an area of active interest and one of the core science questions of the Center for Geospace Storms. In this talk I will describe how addressing this question has informed the development of the Multiscale Atmosphere Geospace Environment (MAGE) model and highlight several recent modeling studies which illustrate the central role of mesoscale processes.

How to cite: Sorathia, K., Michael, A., Sciola, A., Bao, S., Lin, D., Merkin, S., Ukhorskiy, S., Roedig, C., and Garretson, J.: Global modeling of the mesoscale buildup of the ring current and its role in magnetosphere-ionosphere coupling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3445, https://doi.org/10.5194/egusphere-egu23-3445, 2023.

09:50–10:00
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EGU23-8906
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ST2.4
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ECS
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On-site presentation
Sanni Hoilijoki, Veera Lipsanen, Adnane Osmane, Milla Kalliokoski, Harriet George, Lucile Turc, and Emilia Kilpua

Solar wind variations and transients are the main driver of the dynamics of the Earth’s magnetosphere. Interplanetary coronal mass ejections (ICME) cause the largest variations in the near-Earth space, but significant geomagnetic activity can also be driven by high-speed streams (HSSs) and stream interaction regions (SIRs). Solar wind – magnetosphere interactions drive fluctuations in the inner magnetosphere and impact the electrons in the outer radiation belt. Ultra low frequency (ULF) waves in the Pc5 range (2-7mHz) can accelerate electrons in the inner magnetosphere via drift resonance and cause changes in the electron flux up to several orders of magnitude. The different solar wind structures, ICMEs and HSSs/SIRs have been found to have different impact on the ULF waves and electrons in the inner magnetosphere. In this study we use mutual information from information theory to study the statistical dependency of the ULF waves and radiation belt electrons on the solar wind parameters and fluctuations over the solar cycle 23. Unlike Pearson correlation coefficient mutual information can also be used to investigate non-linear statistical dependencies between different parameters. We calculate correlation coefficients separately for each year and find that the non-linearity between the solar wind parameters and some magnetospheric parameters is higher during solar maximum when most of the geomagnetic activity is driven by ICMEs, while the non-linearity decreases during the declining phase, as larger portion of the geomagnetic activity is driven by HSSs and SIRs. To investigate further if the change of the ratio of ICMEs and HSSs is the possible cause of the changes in the non-linearity during the solar cycle, we calculate the correlation coefficients separately during ICMEs, HSSs/SIRs and quiet solar wind.

How to cite: Hoilijoki, S., Lipsanen, V., Osmane, A., Kalliokoski, M., George, H., Turc, L., and Kilpua, E.: Impact of the solar activity on the non-linearity of the statistical dependency between solar wind and the inner magnetosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8906, https://doi.org/10.5194/egusphere-egu23-8906, 2023.

10:00–10:10
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EGU23-17213
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ST2.4
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On-site presentation
Robert Rankin, Dmytro Sydorenko, and Ian R Mann

Electromagnetic ion cyclotron (EMIC) waves are important because of their essential role in reducing the amount of radiation in the Earth's radiation belts under geomagnetic storm conditions. In this presentation, we show results from a new simulation model of EMIC waves and compare them with SWARM satellite data and ground-based observations [I. P. Pakhotin et al., Geophys. Res. Lett., 2022, doi:10.1029/2022GL098249]. The EMIC wave model is a first-of-a-kind in accounting for wave propagation in the magnetosphere and a realistic ionosphere specified using the IRI and MSIS empirical models. The inclusion of a realistic ionosphere in the model enables new pathways to the upper atmosphere to be identified, which is crucial for understanding the waves detected on the ground. We show using a model-data comparison that EMIC wave energy is reflected at different locations in the ionosphere toward the equator to form standing waves. This is a new resonance phenomenoncreated by interference of waves that produces an amplitude peak in the upper atmosphere at lower latitudes, far from the location of the initial source. Understanding such pathways is crucial for correctly diagnosing the location of EMIC wave populations in space, and assessing their role in radiation belt loss.

How to cite: Rankin, R., Sydorenko, D., and Mann, I. R.: New pathways for EMIC wave propagation within the ionosphere: SWARM observations and modelling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17213, https://doi.org/10.5194/egusphere-egu23-17213, 2023.

Coffee break
Chairpersons: Dedong Wang, Chao Yue, Qiugang Zong
10:45–10:55
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EGU23-4797
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ST2.4
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ECS
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On-site presentation
steffy Sara Varghese and Ioannis Kourakis

Space plasmas are often characterized by non-thermal particle distributions that are generally characterized by a high-energy tail that follows a power law for large velocity arguments. For modelling purposes, these are often described by kappa-type distributions (Livadiotis, 2017). Over the past few decades, the kappa distribution has been adopted in interpretations of observations in various space plasma contexts including the solar wind (Chotoo et al., 2000), planetary magnetospheres (Collier and Hamilton, 1995), the outer heliosphere (Decker and Krimigis, 2003) and the inner heliosheath (Livadiotis and McComas, 2012) and also in theoretical models (Hellberg et al., 2009). An abundance of data from the Cassini and Voyager missions has established in Saturn's magnetosphere the coexistence of non-thermal electron populations (of different characteristics). Schippers et al. (2008) analysed the radial distribution of electron populations in Saturn's magnetosphere by using an ad hoc two-kappa model, thus establishing the relevance of multi-kappa models with respect to electron populations in Saturn's magnetosphere. This coexistence of electron clouds (at distinct temperatures) is a key element in our work.

Electrostatic Solitary Waves (ESWs), generally associated with bipolar electric field waveforms observed alongside propagating density disturbances, are known to occur in Saturn's magnetosphere (Pickett et al., 2015). In this study, we have relied on a multi-fluid plasma model to investigate the significance of suprathermal electron populations in determining the characteristics of different types of solitary wave solutions. Our investigation reveals that the spectral index (i.e. the  parameter value related to the cold electron population mainly) is crucial in explaining the difference among different types of nonlinear structures. A comparison with spacecraft observations suggests that our theoretical estimations may be relevant in the interpretation of ESW observations in Saturn's magnetosphere.

References

Chotoo, K., Schwadron, N.A., Mason, G.M., Zurbuchen, T.H., Gloeckler, G., Posner, A., Fisk, L.A., Galvin, A.B., Hamilton, D.C., Collier, M.R., 2000. J. Geophys. Res. Space Phys. 105, 23107–23122. https://doi.org/10.1029/1998JA000015

 

Collier, M.R., Hamilton, D.C., 1995. Geophys. Res. Lett. 22, 303–306. https://doi.org/10.1029/94GL02997

 

Decker, R.B., Krimigis, S.M., 2003. Adv. Space Res. 32, 597–602. https://doi.org/10.1016/S0273-1177(03)00356-9

 

Hellberg, M.A., Mace, R.L., Baluku, T.K., Kourakis, I. and Saini, N.S., 2009. Physics of Plasmas, 16(9), p.094701

 

Livadiotis, G., 2017. Kappa Distributions - Theory and Applications in Plasmas (Elsevier).

 

Livadiotis, G., McComas, D.J., 2012. Astrophys. J. 749, 11. https://doi.org/10.1088/0004-637X/749/1/11

 

Pickett, J.S., Kurth, W.S., Gurnett, D.A., Huff, R.L., Faden, J.B., Averkamp, T.F., Píša, D. and Jones, G.H., 2015. Journal of Geophysical Research: Space Physics120(8), pp.6569-6580.

 

Schippers, P., Blanc, M., André, N., Dandouras, I., Lewis, G.R., Gilbert, L.K., Persoon, A.M., Krupp, N., Gurnett, D.A., Coates, A.J., Krimigis, S.M., Young, D.T., Dougherty, M.K., 2008. J. Geophys. Res. Space Phys. 113, https://doi.org/10.1029/2008JA013098

 

 

How to cite: Varghese, S. S. and Kourakis, I.: On the role of suprathermal electrons on the characteristics of electrostatic solitary waves in Saturn’s magnetosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4797, https://doi.org/10.5194/egusphere-egu23-4797, 2023.

10:55–11:05
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EGU23-8925
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ST2.4
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ECS
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On-site presentation
Oliver Allanson, Jacob Bortnik, Donglai Ma, Adnane Osmane, and Jay Albert

There is a growing body of observational, theoretical and experimental evidence to indicate that a proper description of radiation belt charged particle transport will require new mathematical models, i.e. new partial differential equations. One leading candidate is to extend the ‘standard diffusion equation’ to a more general Fokker-Planck equation in order to include advection coefficients. Ideally, these advection (first-order transport) coefficients should be parameterized by plasma and VLF/ELF electromagnetic wave parameters in a similar manner to that used for the diffusion coefficients. To the authors' knowledge, this goal has not yet been achieved - at least not to obtain an equation that can be/has been implemented into operational global scale numerical models.

In general, advection coefficients are in fact a combination of both ‘drift coefficients’ and derivatives of the diffusion coefficients. In the standard quasilinear formalism, this combination produces advection coefficients that are identically zero because of specific constraints imposed via the Hamiltonian structure, with a derivation often attributed to Landau/Lichtenberg & Lieberman [1].

In this paper [2] we present a new theory that incorporates and builds upon the ‘weak turbulence/quasilinear results’ of [3,4] and demonstrates the breaking of the ‘Landau-Lichtenberg-Liebermann condition’ for the case of high wave amplitudes, or equivalently small timescales.

We therefore obtain:
(i) the standard quasilinear results for small wave amplitudes and long timescales;
(ii) and non-zero advection coefficients - as well as diffusion coefficients - that are valid for short timescales (high wave amplitudes).

These limiting timescales are determined by the electromagnetic wave amplitude. This also demonstrates that one can use what may be considered ‘quasilinear methods’ to obtain interesting new results for ‘nonlinear/high-amplitude’ waves in radiation belt modelling. We verify the results using high-performance test-particle experiments.

References

[1] A.J. Lichtenberg, and M.A. Lieberman, “Regular and Chaotic Dynamics”, 2nd Ed., Springer, 1991

[2] O. Allanson et al (in prep)

[3] D.S. Lemons, PoP, 19, 012306, 2012

[4] O. Allanson, T. Elsden, C. Watt, and T. Neukirch, Frontiers Aston. Space Sci., 8:805699, 2022

How to cite: Allanson, O., Bortnik, J., Ma, D., Osmane, A., and Albert, J.: Radiation belt particle diffusion, drift and advection via cyclotron interactions, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8925, https://doi.org/10.5194/egusphere-egu23-8925, 2023.

11:05–11:15
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EGU23-7785
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ST2.4
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solicited
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On-site presentation
David P. Hartley, Ivar Christopher, Lunjin Chen, Ondrej Santolik, Craig Kletzing, Matthew Argall, and Narges Ahmadi

The dynamics of Earth's outer electron radiation belt is, in part, driven by interactions with whistler-mode chorus waves.  Chorus can cause rapid acceleration of electrons up to relativistic energies, as well as drive precipitation of particles into the atmosphere causing both microbursts and diffuse aurora.  Chorus can propagate in such a way that it crosses the plasmapause boundary and may contribute to the possible sources of plasmaspheric hiss, which itself can cause atmospheric losses of particles and the formation of the slot region between the inner and outer radiation belts.  The direction of the wave vector relative to the background magnetic field is a key parameter for quantifying these processes, since it determines the propagation trajectory of the wave, and is required for calculating the resonance condition of the wave-particle interaction.

The orientation of the wave vector is investigated using both survey mode data and high-resolution burst mode observations from the EMFISIS Waves instrument on the Van Allen Probes spacecraft.  Spatial coverage beyond the Van Allen Probes orbit is provided by burst-mode observations from the FIELDS instrument suite on Magnetospheric Multiscale (MMS).  The polar and azimuthal wave vector angles are considered using both spectral analysis, where the frequency-time structure can be resolved, and instantaneous values, which can be used to identify variations within individual chorus subpackets.  We compare the results from each of these different timescales.  Near strong plasma density gradients, such as those which occur on the boundaries of plasmaspheric plumes, we identify that the wave vector becomes more oblique than the general case where no density gradients are present.  The obliquity of the wave vector is shown to directly relate to both the magnitude of the density gradient, and its proximity to the spacecraft.  

How to cite: Hartley, D. P., Christopher, I., Chen, L., Santolik, O., Kletzing, C., Argall, M., and Ahmadi, N.: The Angular Distribution of Whistler-Mode Chorus Wave Vector Directions from Van Allen Probes and MMS Observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7785, https://doi.org/10.5194/egusphere-egu23-7785, 2023.

11:15–11:25
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EGU23-7524
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ST2.4
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On-site presentation
Ondrej Santolik, Ivana Kolmasova, Ulrich Taubenschuss, Marie Turcicova, and Miroslav Hanzelka

Whistler mode waves interact with different magnetospheric particle populations in the inner magnetosphere and significantly influence particle fluxes in the Earth's radiation belts. Using recently acquired large databases of spacecraft measurements from the Van Allen Probes and Cluster missions we construct new empirical models of whistler mode waves in the inner magnetosphere. We pay special attention to the off-equatorial region, which is often under-sampled in the currently existing models, and to the inter-calibration of data from different spacecraft missions. We take into account the effects of instrumental noise and other artifacts which influence the quality of data at the input of the modeling procedure. Our results show that dawn chorus occurs most often around noon, while its peak average amplitudes are observed during the local night. We also show that off-equatorial plasmaspheric hiss has a strong obliquely propagating component. We further confirm the influence of low plasma density regions on the intensity of chorus.

How to cite: Santolik, O., Kolmasova, I., Taubenschuss, U., Turcicova, M., and Hanzelka, M.: An Empirical Model of Whistler Mode Waves in the Radiation Belt Region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7524, https://doi.org/10.5194/egusphere-egu23-7524, 2023.

11:25–11:35
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EGU23-3188
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ST2.4
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On-site presentation
Frantisek Nemec, Ondřej Santolík, Jyrki Manninen, George B. Hospodarsky, and William S. Kurth

Whistler-mode waves propagating in the Earth’s inner magnetosphere sometimes appear as a set of nearly constant frequency elements separated by a fixed frequency. Such events are typically called line radiation, and they can have two distinct origins. First, events with narrow spectral lines and the frequency spacing corresponding to the base power system frequency (50/100 or 60/120 Hz) are generated by electromagnetic radiation from electric power systems on the ground (power line harmonic radiation, PLHR). Second, waves with broader spectral lines, whose frequency spacing does not correspond to the power system frequency, are believed to be generated by plasma instabilities in the magnetosphere (magnetospheric line radiation, MLR).

Frequencies of line radiation events are typically on the order of a few kHz, while their frequency spacing is on the order of a hundred Hz. Relevant spacecraft observations at larger radial distances are thus very sparse due to the typically low frequency resolution of available measurements, not sufficient to distinguish the line structure. We use high-resolution multicomponent wave measurements performed by the EMFISIS instrument on board the Van Allen Probes during the burst mode to fill this observational gap. We systematically identify the line radiation events and analyze their occurrence and properties. Detailed wave propagation analysis allows us to reveal wave propagation throughout the magnetosphere. We further show that the frequency spacing of MLR events appears to be related to an electrostatic wave observed at the corresponding frequency (≈100 Hz). Finally, conjugate observations performed by the Kannuslehto station in Finland are used to estimate the spatial extent of the events.

How to cite: Nemec, F., Santolík, O., Manninen, J., Hospodarsky, G. B., and Kurth, W. S.: Line radiation events: Properties, generation, and propagation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3188, https://doi.org/10.5194/egusphere-egu23-3188, 2023.

11:35–11:45
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EGU23-8693
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ST2.4
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On-site presentation
Xinlin Li, Declan O'Brien, and Daniel Baker

The Relativistic Electron and Proton Telescope (REPT), consisting of a stack of nine aligned silicon detectors onboard Van Allen Probes, has contributed a great number of discoveries based its nominal data. However, the REPT Pulse Height Analysis (PHA) data set, which was taken every 12 milliseconds (ms), including the pulse height that is proportional to the energy deposit of each individual particle from all nine REPT detectors, has been seldom-tapped. Here we show that this data set actually provides higher energy resolution particle measurements than the typical binned data from REPT. Geant4 simulations are used to extend and improve the electron detecting capabilities of REPT using the PHA data. After replicating the nominal characteristics of REPT in the Geant4 toolbox, new channels for REPT, going from 12 electron channels to 47 and lowering the minimum energy to ~1 MeV, have been formulated. The deep storm-time penetration of MeV electrons into the slot region (2<L<3) and inner belt (L<2) has been investigated. Clear dynamic variations of MeV electrons in these regions are revealed and substantiated by quantitative analysis. This is only an example of how the REPT PHA data will enable us to quantitatively address many more various science questions.

How to cite: Li, X., O'Brien, D., and Baker, D.: Observations and Analysis of Deep Penetrations of MeV Electrons from REPT PHA Data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8693, https://doi.org/10.5194/egusphere-egu23-8693, 2023.

11:45–11:55
|
EGU23-15611
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ST2.4
|
On-site presentation
Theodore Sarris, Xinlin Li, Hong Zhao, Kostis Papadakis, Wenlong Liu, Weichao Tu, Vassilis Angelopoulos, Karl-Heinz Glassmeier, Yoshizumi Miyoshi, Ayako Matsuoka, Iku Shinohara, and Shun Imajo

Magnetospheric ultra-low frequency (ULF) waves are known to cause radial diffusion and transport of hundreds-keV to few-MeV electrons in the radiation belts, as the range of drift frequencies of such electrons overlaps with the frequencies of the waves, leading to resonant interactions. Numerous expressions have been derived to quantitatively describe radial diffusion, so that they can be incorporated in global models of radiation belt electrons; however, most expressions of the radial diffusion rates are derived only for equatorially mirroring electrons, and are based on estimates of the power of ULF waves that are obtained either from spacecraft close to the equatorial plane or from the ground. Recent studies using the Van Allen Probes and Arase have shown that the wave power in magnetic fluctuations is significantly enhanced away from the magnetic equator, consistent with models simulating the natural modes of oscillation of magnetospheric field lines. This has significant implications for the estimation of radial diffusion rates, as higher pitch angle electrons will experience considerably higher ULF wave fluctuations than equatorial electrons. In this talk, we present recent results on the distribution of the magnetic field wave power as a function of magnetic latitude in different local time sectors and under different solar and geomagnetic conditions. Furthermore, using analytic functions of wave amplitudes in 3D test particle simulations, we simulate the change in L over time for particles of different pitch angles; this change in L can be translated to novel analytic diffusion coefficients with pitch-angle, L and energy dependence. In this talk we discuss the potential implications for the radial diffusion rates as currently estimated.

How to cite: Sarris, T., Li, X., Zhao, H., Papadakis, K., Liu, W., Tu, W., Angelopoulos, V., Glassmeier, K.-H., Miyoshi, Y., Matsuoka, A., Shinohara, I., and Imajo, S.: Observations of Off-Equatorial ULF Waves and Simulations of their effects on Radial Diffusion in the Radiation Belts, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15611, https://doi.org/10.5194/egusphere-egu23-15611, 2023.

11:55–12:05
|
EGU23-3375
|
ST2.4
|
ECS
|
On-site presentation
Daniel Ratliff and Oliver Allanson

Whistler-Mode Chorus (WMC) waves are an important contributor to the dynamics of the magnetosphere, not only for their prevalence in measured observations of near-Earth space but also for their dominant role in transporting energy and particles throughout it. It is therefore of key importance to space weather modelling that we understand how WMC waves are generated, how they subsequently evolve and how they interact with the particle populations that they transport. There are also fundamental physics question to answer as WMC waves display nonlinear phenomena rarely seen in other fields, including their ability to raise and lower their frequency repeatedly and rapidly leading to rising and falling tone waves respectively. Are the interactions between the wave and the particles driving such phenomena, and if so to what degree are they doing so?

 

In this talk, we revisit the nonlinear evolution of WMC waves from a theoretical perspective.  Wave-particle interactions are shown to be a key driver of the modulational instabilities that lead to element and subelement formation which are well represented by an extension of the well-known Nonlinear Schrodinger equation. Simulations of this yields power spectrum reminiscent of the rising and falling tone emissions observed in mission data from the Van Allen probes, THEMIS, MMS and Cluster and determines that that wave-particle interactions are the primary cause of this effect. As a result, this nonlinear theory indicates regimes in which these frequency sweeps can be enhanced or dampened, and suggests why the WMC band gap at half the gyrofrequency exists.

How to cite: Ratliff, D. and Allanson, O.: Nonlinear wave-particle interactions in Whistler-Mode Chorus waves: modulation as a route to rising and falling tones, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3375, https://doi.org/10.5194/egusphere-egu23-3375, 2023.

12:05–12:15
|
EGU23-4471
|
ST2.4
|
On-site presentation
Dmitri Vainchtein, Anton Artemyev, Didier Mourenas, and Xiaojia Zhang

The wave-particle resonant interaction is a key process controlling energetic electron flux dynamics in the Earth’s radiation belts. All existing radiation belt codes are Fokker-Planck models relying on the quasi-linear diffusion theory to describe the impact of wave-particle interactions. However, in the outer radiation belt, spacecraft often detect waves sufficiently intense to interact resonantly with electrons in the nonlinear regime.

We propose an approach to (1) estimate the contribution of such nonlinear resonant interactions, and (2) include them into diffusion-based radiation belt models. Using statistics of chorus wave-packet amplitudes and sizes (number of wave periods within one packet), we provide a rescaling factor for the quasi-linear diffusion rates to account for the contribution of nonlinear interactions in long-term electron flux dynamics. Such nonlinear effects may speed up 0.1-1 MeV electron diffusive acceleration by a factor of x2-3 during disturbed periods.

How to cite: Vainchtein, D., Artemyev, A., Mourenas, D., and Zhang, X.: Quantifying the Contribution of Nonlinear Resonant Effects to Diffusion Rates, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4471, https://doi.org/10.5194/egusphere-egu23-4471, 2023.

12:15–12:25
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EGU23-17286
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ST2.4
|
ECS
|
solicited
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Virtual presentation
|
Miroslav Hanzelka, Wen Li, Qianli Ma, and Luisa Capannolo

Electrons in the Earth’s outer radiation belt can experience rapid energization and pitch angle scattering through interactions with naturally generated electromagnetic waves. Cyclotron resonant interactions with large amplitude electromagnetic ion cyclotron (EMIC) emissions cause scattering and major atmospheric losses of relativistic electrons in the sub-MeV and MeV energy range. While theory and simulations in the past focused mostly on parallel propagating waves, in-situ spacecraft observations of EMIC waves commonly show quasi-parallel or moderately oblique propagation.

Here we present the results of test-particle analysis of electron interaction with helium band and hydrogen band EMIC waves parametrized by wave normal angle (WNA) and wave amplitude. It is shown that nonlinear phase trapping and the associated transport of electrons to low-pitch angles become efficient only at very large amplitudes (> 1% of the background magnetic field), especially in the helium band frequency range, making the nonlinear effects less important than in the whistler-electron interaction case. Harmonic resonant interactions with oblique waves further increase the probability of detrapping, pushing the pitch angle evolution closer to pure diffusion. We also analyze the pitch angle behavior near the loss cone and study the evolution of phase space density (PSD) through the Liouville mapping method. Despite the significant advection effects caused by force-bunching of resonant electrons at low pitch angles, the PSD in the loss cone exhibits behavior similar to strong diffusion. We argue that this is expected to be the case for any bursty precipitation caused by cyclotron resonant interactions.

The wave normal angle has only minor impact on the precipitation rate in the energy range affected by the off-equatorial fundamental resonance, except for the case of very oblique waves (WNA > 70 deg). However, since oblique EMIC waves are elliptically polarized and interact with both co-streaming and counter-streaming electrons, they can enhance the changes in the pitch angle of mirrored (trapped) relativistic electrons. The scattering efficiency for counter-streaming electrons strongly depends on the wave ellipticity, and in turn, on wave frequency, wave normal angle, and ion composition. Our simulation results support the need for accurate wave normal angle and amplitude distribution to quantify the relativistic electron precipitation to the Earth’s atmosphere.

How to cite: Hanzelka, M., Li, W., Ma, Q., and Capannolo, L.: Nonlinear Scattering of Relativistic Electrons by Oblique EMIC Waves, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17286, https://doi.org/10.5194/egusphere-egu23-17286, 2023.

Posters on site: Mon, 24 Apr, 14:00–15:45 | Hall X4

Chairpersons: Dedong Wang, Ondrej Santolik, Qiugang Zong
X4.205
|
EGU23-14289
|
ST2.4
Dedong Wang, Yuri Shprits, Ting Feng, Thea Lepage, Ingo Michaelis, Yoshizumi Miyoshi, Yoshiya Kasahara, Atsushi Kumamoto, Shoya Matsud, Ayako Matsuoka, Satoko Nakamura, Iku Shinohara, and Fuminori Tsuchiiya

Chorus waves play an important role in the dynamic evolution of energetic electrons in the Earth’s radiation belts and ring current. Due to the orbit limitation of Van Allen Probes, our previous chorus wave model developed using Van Allen Probe data is limited to low latitude. In this study, we extend the chorus wave model to higher latitudes by combining measurements from the Van Allen Probes and Arase satellite. As a first step, we intercalibrate chorus wave measurements by comparing statistical features of chorus wave observations from Van Allen Probes and Arase missions. We first investigate the measurements in the same latitude range during the two years of overlap between the Van Allen Probe data and the Arase data. We find that the statistical intensity of chorus waves from Van Allen Probes is stronger than those from Arase observations. After the intercalibration, we combine the chorus wave measurements from the two satellite missions and develop an analytical chorus wave model which covers all magnetic local time and extends to higher latitudes. This chorus wave model will be further used in radiation belt and ring current simulations.

How to cite: Wang, D., Shprits, Y., Feng, T., Lepage, T., Michaelis, I., Miyoshi, Y., Kasahara, Y., Kumamoto, A., Matsud, S., Matsuoka, A., Nakamura, S., Shinohara, I., and Tsuchiiya, F.: Developing Chorus Wave Model Using Van Allen Probe and Arase Data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14289, https://doi.org/10.5194/egusphere-egu23-14289, 2023.

X4.206
|
EGU23-3134
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ST2.4
|
ECS
Kristyna Drastichova, František Němec, Jyrki Manninen, and Michel Parrot

We use conjugate observations of magnetospheric whistler mode electromagnetic waves at frequencies up to 16 kHz to determine their typical spatial scales and propagation to the ground. For this purpose, we use data obtained by the DEMETER spacecraft at an altitude of about 700 km and by the ground-based Kannuslehto station in Finland. The overlap between the two data sets corresponds to more than 500 DEMETER half-orbits between November 2006 and March 2008. Two different approaches are used. First, specific wave events observed simultaneously by both the spacecraft and the ground station are analyzed in detail. Second, the correlations of the power spectral densities of measured signals are calculated as a function of the frequency and geomagnetic longitude/L-shell separation. These are used to determine typical longitudinal/L-shell correlation lengths and to discuss wave propagation to the ground.

How to cite: Drastichova, K., Němec, F., Manninen, J., and Parrot, M.: Simultaneous observations of whistler mode waves by the DEMETER spacecraft and the Kannuslehto station, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3134, https://doi.org/10.5194/egusphere-egu23-3134, 2023.

X4.207
|
EGU23-7338
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ST2.4
|
ECS
Dovile Rasinskaite

Substorms can inject electrons of energies ranging from 10s to 100s keV (often called source and seed populations) into the magnetosphere which can be accelerated to relativistic energies and be harmful to space-based infrastructure. Here we present a number density/temperature description of the Earths outer radiation belt obtained by using omni-directional flux and energy measurements from the HOPE and MagEIS instruments from the Van Allen Probe mission. This dataset provides a comprehensive statistical study of the whole Van Allen probe era. Values of number density and temperature are extracted by fitting energy and phase space density in log space to find the distribution function. Zeroth and second moments are taken respectively of the distribution function to find the number density and temperature. A number density/ temperature description is advantageous over an energy/flux description as it allows to differentiate between the transport and heating of electrons. The shape and variation of plasma distributions is also discussed, and general statistical properties presented. The relative importance of transport and heating is also discussed. We will explore the classification of substorm injections (i.e., is the injection a heating or transport of electrons, or a combination of both) and this technique can be extended across more energy ranges. 

How to cite: Rasinskaite, D.: A number density/temperature description of the Earth’s outer radiation belt, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7338, https://doi.org/10.5194/egusphere-egu23-7338, 2023.

X4.208
|
EGU23-17326
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ST2.4
|
ECS
Competition between source and loss processes of radiation belt seed, source, and relativistic electrons induced by a magnetic cloud event
(withdrawn)
Zhengyang Zou, Pingbing Zuo, Binbin Ni, Wentao Zhou, and Jiayun Wei
X4.209
|
EGU23-13125
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ST2.4
|
ECS
Matyas Szabo-Roberts, Yuri Shprits, and Hayley Allison

A distinct population of ultrarelativistic electrons has been observed in the outer radiation belt after several geomagnetic storms, and recent modeling results indicate that an existing seed population, and depletions in plasmasphere electron density, are a necessary condition for the appearance of this electron population. In order to similarly deepen our understanding of the solar wind drivers behind the appearance of these electrons with extreme energy, we catalog storms corresponding to ultrarelativistic enhancements by origin, and begin to establish necessary and sufficient solar wind conditions for these enhancement events. To do so, we perform superposed epoch analysis on a 6 year period from 2012 to 2018, using solar wind data from the Omniweb service, as well as electron flux and electron density data products from the Van Allen Probes mission. We also provide an overview of further modeling objectives and open questions for continued investigation of this electron population.

How to cite: Szabo-Roberts, M., Shprits, Y., and Allison, H.: Investigating Solar Wind Drivers of Ultrarelativistic Electron Enhancements in the Outer Radiation Belt, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13125, https://doi.org/10.5194/egusphere-egu23-13125, 2023.

X4.210
|
EGU23-10543
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ST2.4
|
ECS
Milla Kalliokoski, Michael Henderson, Steven Morley, Emilia Kilpua, Adnane Osmane, Leonid Olifer, Drew Turner, Allison Jaynes, Harriet George, Sanni Hoilijoki, Lucile Turc, and Minna Palmroth

Turbulent and compressed sheath regions ahead of interplanetary coronal mass ejections are key drivers of dramatic changes in the electron fluxes in the Earth’s outer radiation belt. They are also associated with elevated wave activity in the inner magnetosphere. These changes in electron fluxes can occur on timescales of tens of minutes that are not readily captured by a two-satellite mission such as the Van Allen Probes due to long revisit times. The recently released Global Positioning System (GPS) data set, on the other hand, provides a larger number of measurements at a given location within a given amount of time, owing to the many satellites in the constellation. In our statistical study on the impact of sheath regions on the outer radiation belt, we investigated events in 2012-2018 at timescales of 6 hours (Van Allen Probes data) and 30 minutes (GPS data). The study showed that the flux response to sheaths as reported from Van Allen Probes observations is reproduced by GPS data.  We highlight that the shorter timescale allowed by GPS data further confirms that the energy and L-shell dependent flux changes are associated with the sheaths rather than the following ejecta. Additionally, we studied the electron phase space density, which is a key quantity for identifying non-adiabatic electron dynamics. This showed that electrons are effectively accelerated only during geoeffective sheaths (SYM-H < -30 nT). Outer belt losses are common for all sheaths, and the lost electrons are replenished during the early ejecta.

How to cite: Kalliokoski, M., Henderson, M., Morley, S., Kilpua, E., Osmane, A., Olifer, L., Turner, D., Jaynes, A., George, H., Hoilijoki, S., Turc, L., and Palmroth, M.: Outer radiation belt electron flux and phase space density changes during sheath regions of coronal mass ejections from Van Allen Probes and GPS data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10543, https://doi.org/10.5194/egusphere-egu23-10543, 2023.

X4.211
|
EGU23-798
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ST2.4
|
ECS
|
Afroditi Nasi, Christos Katsavrias, Sigiava Aminalragia-Giamini, Nour Dahmen, Antoine Brunet, Constantinos Papadimitriou, Ingmar Sandberg, Sébastien Bourdarie, Viviane Pierrard, Edith Botek, Fabien Darrouzet, Ondrej Santolik, Benjamin Grison, Ivana Kolmasova, David Pisa, Yoshizumi Miyoshi, Wen Li, Hugh Evans, and Ioannis A. Daglis and the Arase Team

During the second half of 2019, the Earth’s magnetosphere was impacted by a sequence of Corotating Interaction Regions (CIRs) during four consecutive solar rotations. Based on the solar wind properties, the CIRs can be divided in four groups, with the 3rd group, which arrived on August-September 2019, resulting in significant multi-MeV electron enhancements, up to ultra-relativistic energies of 9.9 MeV.

Each CIR group has a different effect on the outer radiation belt electron populations; we investigate them by exploiting combined measurements from the Van Allen Probes, THEMIS, and Arase satellites. We produce Phase Space Density (PSD) radial profiles and inspect their dependence on the values of the first and second adiabatic invariants (μ,K), ranging from seed to ultra-relativistic electrons and from near-equatorial to off equatorial mirroring populations, respectively.

Focusing on the 3rd CIR group, and in order to assess the relative contribution of radial diffusion and gyro-resonant acceleration, we perform numerical simulations of the radiation belt environment, combining several relevant models: EMERALD (NKUA), GEO model (NKUA), Salammbô (ONERA), VLF model (IAP), Plasmaspheric model (BIRA-IASB), FARWEST (ONERA). We further compare the temporal evolution of the simulated electron PSD with the above observations.

This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 870437 for the SafeSpace project.

How to cite: Nasi, A., Katsavrias, C., Aminalragia-Giamini, S., Dahmen, N., Brunet, A., Papadimitriou, C., Sandberg, I., Bourdarie, S., Pierrard, V., Botek, E., Darrouzet, F., Santolik, O., Grison, B., Kolmasova, I., Pisa, D., Miyoshi, Y., Li, W., Evans, H., and Daglis, I. A. and the Arase Team: Investigating the acceleration efficiency of VLF and ULF waves on different electron populations in the outer radiation belt through multi-point observations and modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-798, https://doi.org/10.5194/egusphere-egu23-798, 2023.

X4.212
|
EGU23-8042
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ST2.4
|
ECS
Stefan Gohl and František Němec

We use electron flux data measured by the Energetic Particle Telescope (EPT) onboard the Proba-V satellite in a Low Earth Orbit (LEO) to investigate the radiation belt response to the interplanetary shock arrival. Altogether, as many as 31 interplanetary shocks selected from the OMNI data during 2013-2018 are investigated. While the radiation belt fluxes are nearly unaffected by the shock arrival in some cases, other events reveal a sudden drop of energetic electron fluxes spanning over a broad range of L-shells. Electron flux changes at various L-shells and energies are evaluated and compared with the solar wind dynamic pressure change across the shock front, magnetopause location, and z-component of the interplanetary magnetic field. The aim is to identify parameters governing the radiation belt response to the interplanetary shock passage and to understand the strikingly different responses to the seemingly similar solar wind variations.

How to cite: Gohl, S. and Němec, F.: Impact of interplanetary shocks on the radiation belt environment measured by a low altitude satellite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8042, https://doi.org/10.5194/egusphere-egu23-8042, 2023.

X4.213
|
EGU23-3069
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ST2.4
|
ECS
|
Deyu Guo, Zheng Xiang, and Binbin Ni

Atmospheric precipitation of radiation belt electrons plays an important role in the magnetosphere-ionosphere-atmosphere coupling system, which can trigger chemical and electric effects in the upper atmosphere and meanwhile generate aurorae of various types. In the regime of the quasi-linear theory, it is commonly accepted that the population of trapped electrons is no smaller than the precipitated population. However, such a concept has been proved to break down due to the nonlinear wave-particle interactions, which can drive the superfast electron precipitation. Therefore, on basis of the long-term MEPED datasets of POES satellites, we perform a comprehensive analysis of the spatiotemporal characteristics and geomagnetic dependence of superfast radiation belt electron precipitation. Our results demonstrate that superfast atmospheric precipitation of energetic electrons occurs with a non-negligible percentage with respect to the overall electron precipitation observations, and has the geomagnetic dependence similar to that of whistler-mode chorus waves.

How to cite: Guo, D., Xiang, Z., and Ni, B.: A statistical study of superfast atmospheric precipitation of radiation belt electrons observed by POES satellites, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3069, https://doi.org/10.5194/egusphere-egu23-3069, 2023.

X4.214
|
EGU23-12704
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ST2.4
|
ECS
François Ginisty, Frédéric Wrobel, Robert Ecoffet, Mioara Mandea, Alain Michez, Nicolas Balcon, Marine Ruffenach, and Julien Mekki

The SEM-2 (Space Environment Monitor-2) instrument embedded on the NOAA-15 Low Earth Orbit satellite provides measurements of trapped protons in the Van Allen inner belt from 1998 to nowadays. This continuous amount of measurements enables us to study the temporal evolution of the dynamics of the South Atlantic Anomaly (SAA) over more than two solar cycles.
In particular, we study the temporal evolution of the area of the SAA. We observe that the area of the SAA is anti-correlated with the solar activity. Two physical process explain this anticorrelation.
First, the more the Sun is active the more it disables the cosmic rays to reach the Earth Magnetosphere and to fill the inner radiation belt with protons. Then, when the Sun in more active, the upper atmosphere is warmer and therefore absorbs more protons from the radiation belt.
Then, we investigate the protons flux centroid of the SAA. The temporal evolution of its position, latitude and, longitude is studied over the same time interval (1998-2022). We notice the latitude of the centroid is also anti-correlated with the solar activity whereas the longitude seems absolutely
independent. Some explanations are given for these observations.
The temporal evolution of the position of the centroid shows a drift of the SAA. Indeed from 1998 to 2022 the SAA drifted of about 7 degrees West.
The SEM-2 instrument measures flux for protons of different energies (16, 36, 70 and, 140 MeV). For each energy, the SAA dynamic has a similar trend but with different values. These differences are investigated and the results discussed.

How to cite: Ginisty, F., Wrobel, F., Ecoffet, R., Mandea, M., Michez, A., Balcon, N., Ruffenach, M., and Mekki, J.: Studying the South Atlantic Anomaly temporal evolutionfrom 1998 to 2022 using the SEM-2 proton flux, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12704, https://doi.org/10.5194/egusphere-egu23-12704, 2023.

X4.215
|
EGU23-15928
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ST2.4
Patrizia Francia, Marcello DE Lauretis, Mirko Piersanti, Giulia D'Angelo, and Alexandra Parmentier

Electron precipitation driven by electromagnetic ion cyclotron (EMIC) waves in the Pc1 range (0.1–5Hz) has been suggested as a significant loss mechanism for outer radiation belt fluxes of electrons in the 1–5 MeV energy range. Moreover, EMIC waves have been also observed to cause significant precipitation of ring current protons during geomagnetic storms.
In this study we report the concurrent observations of electromagnetic ion cyclotron Pc1 waves in both ionospheric F-region and at ground. Key event on March 29, 2021 shows that high latitude ground magnetometers in Antarctica and CSES LEO satellite detected concurrent Pc1 wave and energetic proton precipitation. In the ionospheric F-layer above the Auroral zone, the CSES satellites observed transverse Pc1 waves and localized plasma density enhancement, which is occasionally surrounded by wide/shallow depletion. This might indicate that EMIC wave-induced proton precipitation contributes to the energy transfer from the magnetosphere to the ionosphere and to the ionization of the F-layer.

How to cite: Francia, P., DE Lauretis, M., Piersanti, M., D'Angelo, G., and Parmentier, A.: Proton precipitation from EMIC waves at high latitudes: A casestudy from 29 March 2021, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15928, https://doi.org/10.5194/egusphere-egu23-15928, 2023.

X4.216
|
EGU23-16056
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ST2.4
|
ECS
|
|
Liliana Macotela, Jyrki Manninen, and Martin Fullekrug

Analysis of very low frequency (VLF) radio waves provides us the remarkable possibility of investigating the response of both the lower ionosphere and magnetosphere to a diversity of transient and long-term physical phenomena originating on Earth (e.g., atmospheric waves) or in space (e.g., CMEs). In this work, broadband VLF data measured at Kannuslehto, in northern Finland, is used to characterize a new type of VLF emissions displaying a strip-like structure observed in the 5–39 kHz frequency range. Analyzing campaigns from 2006 to 2022, we found that this emission can be observed either in the high VLF frequency ranges or spanning from low to high frequency ranges. We also found that the events last usually less than 1 hour, occur during evening hours, and during quiet geomagnetic conditions. We discuss the seasonal dependence of this kind of events by analyzing a complete year during 2022. We also discuss whether their origin might be due to plasma instabilities in the magnetosphere, as in the case of auroral hiss.

How to cite: Macotela, L., Manninen, J., and Fullekrug, M.: VLF banded structured events observed in the 5–39 kHz frequency range in Finland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16056, https://doi.org/10.5194/egusphere-egu23-16056, 2023.

X4.217
|
EGU23-15979
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ST2.4
|
ECS
Margot Decotte, Spencer Hatch, Karl Laundal, and Jone Reistad

Following the work done with the DMSP spectrometer data to derive the auroral occurrence probability in all covered MLat-MLT sectors above 50 degrees MLat (Decotte et al. 2023), here we use the Swarm magnetometer data to extract the probability to detect magnetic field perturbations in the East--West direction. We derive the integrated spectral density from the magnetic field data in a given frequency band, and we define a minimum power threshold above which fluctuations would indicate field-aligned currents. We obtain MLat-MLT distributions of magnetic field fluctuations for various geomagnetic conditions. We find strong similarities between the preferred region of magnetic perturbations and the Xiong and Lühr auroral boundaries (2014), suggesting that the auroral oval morphology could be investigated through magnetic field spectral power estimates. We compare the magnetic field fluctuation probability with the auroral occurrence probability (DMSP particle data) and we find a recurrent dawn-dusk asymmetric pattern in both distributions.  

How to cite: Decotte, M., Hatch, S., Laundal, K., and Reistad, J.: Auroral oval identification based on Swarm magnetometer data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15979, https://doi.org/10.5194/egusphere-egu23-15979, 2023.

X4.218
|
EGU23-11056
|
ST2.4
Kun Li

The polar wind, consisting of low-energy ions and electrons, is an outflow along the open magnetic field lines from the polar cap ionosphere to the magnetosphere. Previous studies found that both solar radiation and solar wind electromagnetic energy are the two main energy sources for the polar wind. The polar rain, being field-aligned precipitating electrons from the solar wind to the polar cap, may provide additional energies for the polar wind. This scenario is complicated as simulation studies show that polar rain changes the electric potential structures over the polar cap ionosphere. It is unclear how the polar rain affects the polar wind ion outflow. In this study, we show a positive correlation between the polar wind and the polar rain. Meanwhile, the polar wind is generally diminished in regions with strong Earth’s magnetic field, suggesting the B modulates the penetration depth of the polar rain through the magnetic mirror force and thus the energy dissipation of the polar rain. Therefore, the polar rain can be an additional energy source for the polar wind although the polar rain has generally smaller energies and intensities than the particle precipitations in the auroral regions.

How to cite: Li, K.: The effects of the polar rain on the polar wind ion outflow from the nightside ionosphere, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11056, https://doi.org/10.5194/egusphere-egu23-11056, 2023.

X4.219
|
EGU23-11084
|
ST2.4
|
ECS
|
Bernhard Haas, Yuri Y. Shprits, Michael Wutzig, Dedong Wang, and Mátyás Szabó-Roberts

The Earth’s magnetic field traps charged particles which are transported longitudinally around Earth, generating a near-circular current, known as the ring current. While the ring current has been measured on the ground and space for many decades, the enhancement of the ring current during geomagnetic storms is still not well understood, due to many processes contributing to its dynamics on different time scales. The low energy part of the ring current of 10-50 keV is responsible for surface charging effects on spacecraft, potentially causing satellite anomalies.

Here, we show that existing ring current models systematically overestimate the in-situ satellite measurements of the Earth’s night side electron ring current during geomagnetic storms. By analyzing electron drift trajectories during the storm onset, we show that this systematic overestimation of flux can be explained through a missing loss process which operates in the pre-midnight sector. Quantifying this loss reveals that the theoretical upper limit of strong diffusion has to be reached in a broad region of space in order to reproduce the observed flux. We include this missing loss process and show that predictions of electron flux can be significantly improved. Identifying missing loss processes in ring current models is vital to accurately predict storm time dynamics and the associated hazards, that result from a delicate balance of source and loss processes.

How to cite: Haas, B., Shprits, Y. Y., Wutzig, M., Wang, D., and Szabó-Roberts, M.: A Missing Dusk-side Loss Process in the Electron Ring Current, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11084, https://doi.org/10.5194/egusphere-egu23-11084, 2023.

Posters virtual: Mon, 24 Apr, 14:00–15:45 | vHall ST/PS

Chairpersons: Chao Yue, Qiugang Zong, Dedong Wang
vSP.1
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EGU23-10513
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ST2.4
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ECS
Shreedevi Porunakatu Radhakrishna, Yiqun Yu, Yoshizumi Miyoshi, Xingbin Tian, Minghui Zhu, Sandeep Kumar, Satoko Nakamura, Chae-Woo Jun, Masafumi Shoji, Kazuo Shiokawa, Vania Jordanova, Tomoaki Hori, Kazushi Asamura, Iku Shinohara, Shoichiro Yokota, Satoshi Kasahara, Kunihiro Keika, Ayako Matsuoka, Martin Connors, and Akira Kadokura

Recent studies have shown that the ion precipitation induced by EMIC waves can contribute significantly to the total energy flux deposited into the ionosphere and severely affect the magnetosphere-ionosphere coupling. During the geomagnetic storm of 27-28 May 2017, the ARASE and the RBSPa satellites observed typical signatures of EMIC waves in the inner magnetosphere. The DMSP and MetOp satellites observed enhanced proton precipitation during the main phase of the storm. In order to understand the evolution of proton precipitation into the ionosphere, its correspondence to the time and location of excitation of the EMIC waves and its relation to the source and distribution of proton temperature anisotropy, we conducted two simulations of the BATSRUS+RAMSCBE model with and without EMIC waves included. Simulation results suggest that the H- and He-band EMIC waves are excited within regions of strong temperature anisotropy of protons in the vicinity of the plasmapause. In regions where the Arase/RBSPa satellite measurements recorded EMIC wave activity, an increase in the simulated growth rates of H- and He-band EMIC waves is observed indicating that the model is able to capture the EMIC wave activity. The RAM-SCBE simulation with EMIC waves reproduces the precipitating fluxes in the premidnight sector fairly well, and is found to be in good agreement with the DMSP and MetOp satellite observations. The results suggest that the EMIC wave scattering of ring current ions gives rise to the proton precipitation in the premidnight sector at subauroral latitudes during the main phase of the 27 May 2017 storm.

How to cite: Porunakatu Radhakrishna, S., Yu, Y., Miyoshi, Y., Tian, X., Zhu, M., Kumar, S., Nakamura, S., Jun, C.-W., Shoji, M., Shiokawa, K., Jordanova, V., Hori, T., Asamura, K., Shinohara, I., Yokota, S., Kasahara, S., Keika, K., Matsuoka, A., Connors, M., and Kadokura, A.: EMIC wave induced proton precipitation during the 27-28 May 2017 storm:Comparison of BATSRUS+RAM-SCB simulations with ground/space based observations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10513, https://doi.org/10.5194/egusphere-egu23-10513, 2023.

vSP.2
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EGU23-13189
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ST2.4
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ECS
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Adamantia Dimitrakoula, Alexandra Triantopoulou, Afroditi Nasi, Christos Katsavrias, Ioannis A. Daglis, and Ingmar Sandberg

The outer Van Allen radiation belt stands out for its intense variability, due to the complex mechanisms that take place due to the Sun – Earth coupling. One fundamentally important effect is the acceleration of seed electrons to relativistic and ultra – relativistic energies, through different mechanisms, namely radial diffusion and local acceleration.

In our work, we examine 46 events from the Van Allen Probes era (2012 – 2018), which we categorize according to the interplanetary driver of the geomagnetic disturbance. In particular, we study 16 events caused by Interplanetary Coronal Mass Ejections (ICMEs) and 30 events caused by High Speed Streams (HSS), following Stream Interaction Regions (SIRs), for which we calculate the electron Phase Space Density (PSD) for distinct values of the first adiabatic invariant (μ = 100, 1000, 5000 MeV/G) corresponding to seed, relativistic and ultra – relativistic electrons in the outer radiation belt. Furthermore, we perform a Superposed Epoch Analysis (SEA) of the geomagnetic disturbance events, which lead to either enhancements or depletions of the electron PSD, taking into consideration the parameters of solar wind activity, the state of the magnetosphere and the values of the second adiabatic invariant (K = 0.03, 0.09, 0.15 G1/2RE). We discuss the effects of the drivers on the variability of the outer radiation belt and how the different electron populations are affected, by comparing the time and radial profiles of the PSD. Our results lead to a clear difference between the two drivers, as far as it concerns the acceleration mechanisms.

How to cite: Dimitrakoula, A., Triantopoulou, A., Nasi, A., Katsavrias, C., Daglis, I. A., and Sandberg, I.: Impact of Interplanetary Coronal Mass Ejections and High Speed Streams on the dynamic variations of the electron population in the outer Van Allen belt, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13189, https://doi.org/10.5194/egusphere-egu23-13189, 2023.

vSP.3
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EGU23-10778
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ST2.4
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ECS
Sandeep Kumar, Yoshizumi Miyoshi, Vania Koleva Jordanova, Lynn M Kistler, Inchun Park, Porunakatu Radhakrishna Shreedevi, Kazushi Asamura, Shoichiro Yokota, Satoshi Kasahara, Yoichi Kazama, Shiang -Yu Wang, Sunny W. Y. Tam, Takefumi Mitani, Nana Higashio, Kunihiro Keika, Tomo Hori, Chae-Woo Jun, Ayako Matsuoka, Shun Imajo, and Iku Shinohara

Geomagnetic storms are the main component of space weather. Enhancement of the ring current is a typical feature of the geomagnetic storm and a global decrease in the H component of the geomagnetic field is observed during the main phase of the geomagnetic storm.  The ring current represents a diamagnetic current driven by the plasma pressure in the inner magnetosphere. The plasma pressure is mainly dominated by protons in an energy range of a few to a few hundred keVs during quiet times. The O+ contribution is also important, and sometimes dominates more than H+ during intense geomagnetic storms. However, electron contribution to the ring current is not studied well. Recently, we showed that the electron pressure also contributes to the depression of ground magnetic field during the November 2017 CIR-driven storm by comparing Ring current Atmosphere interactions Model with Self Consistent magnetic field (RAM-SCB) simulation, Arase in-situ plasma/particle data, and ground-based magnetometer data [Kumar et al., 2021]. Arase satellite observed 26 geomagnetic storms driven by Corotating Interaction Regions (CIR) during 2017-2021. In this study, we examine statistically the spatial and temporal distribution of ions (H+, He+, O+) and electrons pressure as a function of magnetic local time, L shell and wide range of energies during prestorm, main phase, early recovery and late recovery phase for 26 CIR storms using in situ plasma/particle data obtained by Arase. The results indicate that the electrons (20-50 keV) contribution to the ring current pressure is non-negligible.

How to cite: Kumar, S., Miyoshi, Y., Jordanova, V. K., Kistler, L. M., Park, I., Shreedevi, P. R., Asamura, K., Yokota, S., Kasahara, S., Kazama, Y., Wang, S.-Y., Tam, S. W. Y., Mitani, T., Higashio, N., Keika, K., Hori, T., Jun, C.-W., Matsuoka, A., Imajo, S., and Shinohara, I.: Plasma pressure distribution of ions and electrons in the inner magnetosphere during CIR driven storms observed during Arase satellite era, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10778, https://doi.org/10.5194/egusphere-egu23-10778, 2023.

vSP.4
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EGU23-16202
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ST2.4
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ECS
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Coralie Neubüser, Roberto Battiston, Francesco Maria Follega, William Jerome Burger, Mirko Piersanti, and Dario Recchiuti

Ground-based very low frequency (VLF; 10-30kHz) transmitters have been found in previous studies to emit whistler waves that can re- sonate with high-energy particles (>100keV) in the radiation belt, causing energetic electron precipitation via pitch angle scattering. In the attempt to find a similar mechanism responsible for electron precipitation due to EM waves emitted during seismic events, we ha- ve analysed three years of data (2019-2021) from the China Seismo- Electromagnetic Satellite (CSES) and the NOAA POES satellites. We found enhanced electron fluxes due to the 19.8kHz waves of the NWC transmitter in Australia at L-shell values of about 1.5 and 1.8 at energies up to 400keV in the data of the CSES and NOAA POES-19 sa- tellite, respectively. The enhanced fluxes can be followed along the drift shells from Australia eastwards, and are observed to be lost in the the South Atlantic Anomaly (SAA) due to the interaction with the atmosphere. The high energy resolution of the HEPP-L detector on board CSES of 11keV from 0.1 to 3MeV allows a detailed study of the signal and we will present the expected energy-dispersed wisp struc- ture in L-shell. Finally, we will present our latest results on the identification of isolated electron bursts and the assignment to dif- ferent VLF transmitters, which includes the correlation of VLF wave measurements from ground and space-based instruments to determined on/off periods of the transmitters.

How to cite: Neubüser, C., Battiston, R., Follega, F. M., Burger, W. J., Piersanti, M., and Recchiuti, D.: Observation of VLF transmitter induced electron precipitation of up to 400keV, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16202, https://doi.org/10.5194/egusphere-egu23-16202, 2023.