ST2.1 | Open Session on the Magnetosphere
Orals |
Mon, 08:30
Posters on site
Mon, 16:15
EDI
Open Session on the Magnetosphere
Convener: Yulia Bogdanova | Co-conveners: Andrey Samsonov, C.-Philippe Escoubet, Lucile Turc, Yann Pfau-Kempf, Tianran Sun, David Sibeck
Orals
| Mon, 15 Apr, 08:30–12:30 (CEST), 14:00–15:45 (CEST)
 
Room L1
Posters on site
| Attendance Mon, 15 Apr, 16:15–18:00 (CEST) | Display Mon, 15 Apr, 14:00–18:00
 
Hall X3
Orals |
Mon, 08:30
Posters on site
Mon, 16:15
The session combines presentations submitted to two sessions, Open Session on the Magnetosphere and Global magnetospheric dynamics in simulations and observations. The Open Session on the Magnetosphere traditionally invites presentations on all aspects of the Earth’s magnetospheric physics, including the magnetosphere and its boundary layers, magnetosheath, bow shock and foreshock as well as solar wind-magnetosphere-ionosphere coupling. This session welcomes contributions on various aspects of magnetospheric observations, remote sensing of the magnetosphere’s processes, modelling and theoretical research. The presentations related to the current and planned space missions and to the value-added data services are also encouraged. This session is suitable for any contribution which does not fit more naturally into one of the specialised sessions and for contributions of wide community interest.

The Global magnetospheric dynamics session is dedicated to global large-scale magnetospheric dynamics in simulations and observations. The magnetospheric state is mainly controlled by solar wind conditions. However, solar wind properties change when plasma moves through the bow shock and magnetosheath, therefore the magnetic reconnection rate at the dayside magnetopause depends on parameters in the surrounding magnetosheath and magnetosphere. While global magnetospheric dynamics is understood in terms of the Dungey cycle, several open questions remain, including understanding of different magnetospheric regimes and their drivers, ionospheric feedback, and role of Kelvin-Helmholz instability in the energy transfer from the solar wind into the magnetosphere. Global magnetospheric dynamics can be studied by means of sophisticated numerical simulations, with empirical and semi-empirical models, or using multipoint in situ spacecraft observations. Arrays of ground-based observatories and a fleet of 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. Global imaging missions (e.g., TWINS, LEXI, SMILE, EZIE, GEO-X) can complete this picture providing large-scale snapshots of geospace regions. This session welcomes any work presenting results on the global dynamics of the Earth’s magnetosphere as well as the magnetospheres of other planets.

Orals: Mon, 15 Apr | Room L1

Chairpersons: Yulia Bogdanova, Yann Pfau-Kempf
08:30–08:35
5-minute convener introduction
08:35–08:45
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EGU24-2835
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On-site presentation
Conformal mapping for the magnetosheath modeling problems 
Yasuhito Narita, Daniel Schmid, and Henry Holzkamp

Determining the plasma flow and magnetic field in the terrestrial and planetary magnetosheath region is a challenge both in theoretical and observational studies in space plasma physics. We are motivated by the discovery of the Kobel-Flückiger exact solution for the Laplace equation to the scalar shielding potential for the parabolic geometry of the magnetosheath, and develop a novel algorithm of the conformal mapping to exactly transform the Kobel-Flückiger scalar potential onto a user-specified, arbitrary geometry of the magnetosheath. The algorithm starts with the outer and innter boundary models (e.g., bow shock and magnetopause locations in the case of planetary magnetospheres). The shell variable v is constructed by smoothly interpolating between the two boundaries, and the connector variable u (connecting between the two boundaries in an orthogonal fashion to the shell variable) is determined by evaluating the gradient of the shell variable along the shell segment under the Cauchy-Riemann relations. The conformal mapping method is computationally by far inexpensive, and retains the exactness character of the steady-state magnetosheath solution. The method has a wide range of applications such as validating the numerical simulations, planning the space (planetary and heliospheric) missions, and even estimating the solar wind condition from the magnetosheath data.

How to cite: Narita, Y., Schmid, D., and Holzkamp, H.: Conformal mapping for the magnetosheath modeling problems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2835, https://doi.org/10.5194/egusphere-egu24-2835, 2024.

08:45–08:55
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EGU24-2051
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On-site presentation
3D Structure of the Magnetosheath Jets: Global Hybrid-Kinetic Simulations. 
Shahab Fatemi, Maria Hamrin, Eva Krämer, Herbert Gunell, Gabriella Nordin, Tomas Karlsson, and Oleksandr Goncharov

Over the past 25 years, several spacecraft have observed localized, high-pressure regions that sporadically appear in Earth’s magnetosheath, known as the “magnetosheath jets”. Despite previous analyses, the nature of these transient events remains elusive, marked by a range of uncertainties. These uncertainties mainly stem from the fact that oversimplified assumptions have been made in earlier analyses, where the jets are often portrayed as basic cylinder-like structures. This simplification is primarily because of two reasons: First, spacecraft observations in specific magnetosheath locations couldn't comprehensively cover and explore large spatial areas, providing only a limited perspective on the jets. Second, previous models used to study magnetosheath jets were either two-dimensional (2D) spatial models or three-dimensional (3D) with reduced scales of the Earth's magnetosphere to minimize computational complexity when dealing with Earth.

In this study, we use Amitis, a high-performance, three-dimensional (3D in both configuration and velocity spaces), time-dependent hybrid-kinetic plasma model (kinetic ions, fluid electrons) that runs in parallel on Graphics Processing Units (GPUs). We present, for the first time, the global kinetic interaction between the solar wind and the entire magnetosphere of Earth using its true scales. Achieving this level of accuracy in kinetic modeling of the solar wind plasma interaction with Earth has been a long-standing challenge. Our 3D, time-dependent hybrid-kinetic simulations dispel the notion that the magnetosheath jets are simple cylinders. Instead, our simulations show that the magnetosheath jets exhibit complex and interconnected structures with dynamic 3D characteristics. As they move through the magnetosheath, they wrinkle, fold, merge, and split in complex ways before a subset reaches the magnetopause. Our findings are pivotal in advancing our understanding of magnetosheath jets and their significance in coupling between the solar wind and Earth's magnetosphere.

How to cite: Fatemi, S., Hamrin, M., Krämer, E., Gunell, H., Nordin, G., Karlsson, T., and Goncharov, O.: 3D Structure of the Magnetosheath Jets: Global Hybrid-Kinetic Simulations., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2051, https://doi.org/10.5194/egusphere-egu24-2051, 2024.

08:55–09:05
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EGU24-2677
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On-site presentation
Electron Scale Coherent Structure as Micro Accelerator in the Earth’s Magnetosheath 
Zikang Xie, Qiu-Gang Zong, Chao Yue, Xu-Zhi Zhou, Zhi-Yang Liu, Jian-Sen He, Yi-Xin Hao, Chung-Sang Ng, Hui Zhang, Shu-Tao Yao, Craig J. Pollock, Guan Le, Robert E. Ergun, and Per-Arne Lindqvist

Turbulent energy dissipation is a fundamental process in plasma physics that has not been settled. It is generally believed that the turbulent energy is dissipated at electron scales leading to electron energization in magnetized plasmas. Here, we propose a micro accelerator which could transform electrons from isotropic distribution to trapped, and then to stream (Strahl) distribution. From the MMS observations of an electron-scale coherent structure in the dayside magnetosheath, we identify an electron flux enhancement region in this structure collocated with an increase of magnetic field strength, which is also closely associated with a non-zero parallel electric field. We propose a trapping model considering a field-aligned electric potential together with the mirror force. The results are consistent with the observed electron fluxes from ~50 eV to ~200 eV. It further demonstrates that bidirectional electron jets can be formed by the hourglass-like magnetic configuration of the structure.

How to cite: Xie, Z., Zong, Q.-G., Yue, C., Zhou, X.-Z., Liu, Z.-Y., He, J.-S., Hao, Y.-X., Ng, C.-S., Zhang, H., Yao, S.-T., Pollock, C. J., Le, G., Ergun, R. E., and Lindqvist, P.-A.: Electron Scale Coherent Structure as Micro Accelerator in the Earth’s Magnetosheath, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2677, https://doi.org/10.5194/egusphere-egu24-2677, 2024.

09:05–09:25
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EGU24-4304
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solicited
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Highlight
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On-site presentation
Predictability of Magnetopause Location 
Zdenek Nemecek and Jana Safrankova

Understanding the dynamics and predictability of magnetopause location is crucial for space weather forecasting and the safeguarding of critical technological infrastructure. The first part of the talk surveys previous effort in development of magnetopause models that gradually involve more and more driving parameters, starting from solar wind dynamic pressure, interplanetary magnetic field (IMF) magnitude and orientation, tilt angle of the Earth dipole and/or IMF cone angle. We show that, in spite of different forms of the magnetopause surface and different functions used for quantification of effects of driving parameters, their ability of prediction of magnetopause location is nearly identical in a statistical sense. Following this survey, we discuss main contributors to the uncertainty of this prediction like variations of upstream parameters or effects of other parameters not included in the present models and suggest a possible way for development of a new, more precise, model. The last part of the talk discusses effects of foreshock and magnetosheath transients that are unpredictable but that can result in extreme magnetopause displacements.

How to cite: Nemecek, Z. and Safrankova, J.: Predictability of Magnetopause Location, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4304, https://doi.org/10.5194/egusphere-egu24-4304, 2024.

09:25–09:35
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EGU24-4337
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ECS
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Highlight
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On-site presentation
A time-dependent three-dimensional magnetopause model based on quasi-elastodynamic theory 
Yaxin Gu, Yi Wang, Fengsi Wei, Xueshang Feng, Andrey Samsonov, Xiaojian Song, Yalan Chen, Boyi Wang, Pingbing Zuo, and Chaowei Jiang

The interaction between the solar wind and the Earth’s magnetosphere is one of the most important research topics in space weather and space plasma physics. The finding of the exact magnetopause position significantly enhances our knowledge of magnetospheric response to solar wind variations. While numerous magnetopause models have been constructed in the past decades, a substantial portion of them remains time-independent models, posing limitations in elucidating the dynamic movement of the magnetopause under varying solar wind conditions. This study pioneers the establishment of a time-dependent three-dimensional magnetopause model grounded in the quasi-elastodynamic pressure theory, named the POS (Position, Overall oscillation and Surface wave like-structure) model. In contrast to the existing time-dependent magnetopause models (except for numerical simulations), the POS model transcends the one-dimensional framework, providing a real-time depiction of magnetopause position and shape alterations. The model's validity is substantiated through comparisons with satellite observation. Based on an extensive dataset of satellite magnetopause crossings (exceeding 40,000 magnetopause crossing events), the POS model exhibits superior predictive accuracy (as evaluated by root-mean-square error) compared to six widely employed magnetopause models. Remarkably, the POS model demonstrates heightened efficacy under highly disturbed solar wind conditions as well as in high-latitude and flank region of magnetopause and it possesses characteristics as predictive accuracy, concise formulation, and fast computational speed. The introduction of a time-dependent three-dimensional dynamic magnetopause model not only advances our comprehension of the physical processes in space plasma and enhances our predictive capabilities for space weather on the Earth but also provides valuable insights into the dynamic processes in the magnetospheres of other planets. 

How to cite: Gu, Y., Wang, Y., Wei, F., Feng, X., Samsonov, A., Song, X., Chen, Y., Wang, B., Zuo, P., and Jiang, C.: A time-dependent three-dimensional magnetopause model based on quasi-elastodynamic theory, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4337, https://doi.org/10.5194/egusphere-egu24-4337, 2024.

09:35–09:45
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EGU24-1530
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ECS
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On-site presentation
Modeling soft X-ray emissions at the dayside magnetopause 
Qiuyu Xu, Dimitra Koutroumpa, Ronan Modolo, Tianran Sun, Hyunju Connor, and Steve Sembay

In this study, we simulate the Solar Wind Charge Exchange (SWCX) soft X-ray emissions at dayside magnetopause by using magnetohydrodynamic (MHD) and Test-Particle (TP) models. Due to the single fluid description, the MHD model is unable to resolve the particle kinetic effects or distinguish the magnetospheric plasma and the solar wind plasma. We investigate these effects with the TP model. As the TP model does not self-compute magnetic and electric field, the magnetic and electric field data obtained from OpenGGCM and PPMLR MHD model are used as the input to TP model. The soft X-ray emissivity maps simulated from pure OpenGGCM and PPMLR MHD approaches and from TP-OpenGGCM and TP-PPMLR MHD approaches are presented and compared. The results indicate that the TP model can well resolve the kinetic effects and the individual spectral characteristics, and it does not require a masking method in the magnetosphere. Therefore the TP model is a complementary approach for simulating the X-ray emissions in the dayside magnetosheath and cusps.

How to cite: Xu, Q., Koutroumpa, D., Modolo, R., Sun, T., Connor, H., and Sembay, S.: Modeling soft X-ray emissions at the dayside magnetopause, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1530, https://doi.org/10.5194/egusphere-egu24-1530, 2024.

09:45–09:55
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EGU24-17183
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ECS
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On-site presentation
Evolution of Atmospheric Oxygen Escape on Earth since the Paleoproterozoic Era 
Maria Luisa Alonso Tagle, Romain Maggiolo, Herbert Gunell, Gael Cessateur, Johan De Keyser, Iannis Dandouras, Aline Vidotto, Caue Borlina, Claire Nicholson, Giovanni Lapenta, Viviane Pierrard, and Ann Carine Vandaele

Understanding atmospheric escape over geological timescales is essential to constrain the planet’s ability to retain its atmosphere and thus sustain life. Atmospheric particles are energized through solar radiation and plasma interactions between the solar wind, the Earth’s magnetosphere, and ionosphere, escaping through various mechanisms.

For Earth, several missions provided measurements of the oxygen escape rate. However, measurements are for current solar and planetary conditions that strongly differ from the past conditions (e.g. stronger solar wind, higher solar EUV radiation). The main challenge to estimate the past escape rate is to extrapolate current measurements to the past solar system environment.

Since the Great Oxidation Event, 2.45 Gyr. ago, there is a significant amount of oxygen in the atmosphere. The goal of this study is to assess the stability of oxygen on Earth concerning atmospheric escape. We developed a semi-empirical model, which considers seven different escape mechanisms to estimate the net oxygen escape on Earth since this event. We use models available in the literature to describe the past solar wind and solar radiation, the Earth’s magnetic moment history, and the Earth’s exosphere evolution due to the change of solar EUV radiation while considering a constant atmospheric composition. The escape rate is calculated for these previous conditions considering a physical scaling and/or empirical formulas per mechanism.

We estimate that the total oxygen loss during the last 2.45 Gyr., reaches almost 30% of the current atmospheric oxygen content. Oxygen escape is dominated by polar processes, polar wind and cusp escape, contributing over 90% of the total loss. Polar wind is the leading erosion mechanism before ~1.5 Gyr. while escape from the polar cusp dominates at present.

How to cite: Alonso Tagle, M. L., Maggiolo, R., Gunell, H., Cessateur, G., De Keyser, J., Dandouras, I., Vidotto, A., Borlina, C., Nicholson, C., Lapenta, G., Pierrard, V., and Vandaele, A. C.: Evolution of Atmospheric Oxygen Escape on Earth since the Paleoproterozoic Era, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17183, https://doi.org/10.5194/egusphere-egu24-17183, 2024.

09:55–10:05
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EGU24-712
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Highlight
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On-site presentation
Metals in Earth’s Magnetosphere: From Ionosphere or Moon?  
Mei-Yun Lin and Andrew Poppe

Recent observations by the Geotail and Cluster missions in the magnetosphere have revealed the presence of singly charged metallic ions, such as Mg+ and Fe+. However, the origins and transport mechanisms of these metallic ions are unknown. Metallic ions are prevalent in the Earth's lower atmosphere, primarily produced from the ablation of meteoroids and the formation of metal layers. Similarly, metallic ions are also common in the vicinity of the Moon's surface, where they are created from the ionization of the lunar exosphere, a thin neutral atmosphere that surrounds the Moon. To deepen our understanding of the sources of the metallic ions in the magnetosphere, this study develops different strategies to evaluate the contributions of metallic ion outflow from the ionosphere and the Moon across different solar and geomagnetic conditions. 

 

To estimate the metallic ion outflow from the ionosphere, we utilize a physics-based model, PWOM, which solves the transport of ionospheric outflow for all the relevant ion species, such as H+, He+, N+, O+, and molecular ions. As metallic ions are mainly produced via charge exchange between molecular ions and metal atoms in the ionosphere, the abundance of metallic ion outflow is represented by the densities of molecular ions with adjusted ratios. In addition, the metallic ion upflow will be further accelerated to outflow in the high-altitude ionosphere via the energization of wave-particle interaction. This vertical transport of metallic ions is further tracked by PWOM and shows a strong connection with the wave energy input.

 

On the other hand, metallic ion outflow from the Moon is inferred from LADEE and ARTEMIS observational data. These pickup ions are generated through charge exchange or electron impact from the metallic neutrals, which are primarily produced through either charged particle sputtering or micrometeoroid impact vaporization of the lunar surface. The abundances of metallic neutrals are derived from information on sputter yields and observed ion fluxes. Once the densities of neutral metal species are obtained, the metallic pickup ion fluxes are further calculated based on the relevant ionization cross sections with incoming electron and ion fluxes to the lunar exosphere. We use in-situ ARTEMIS observations of ion and electron fluxes to properly calculate these ionization rates. 

 

This study will be the first to compare the contributions of ionospheric outflow and lunar pickup ions to the magnetosphere. Moreover, by utilizing observational data from ARTEMIS, the variations of sources of metallic ions will be analyzed as the Moon passes through the upstream solar wind, magnetosheath, and magnetotail. The differences between the outflow of metallic ions from the ionosphere and the Moon can be used as a tracer to better understand the transport and energization processes of heavy ion plasma in the magnetosphere. 

How to cite: Lin, M.-Y. and Poppe, A.: Metals in Earth’s Magnetosphere: From Ionosphere or Moon? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-712, https://doi.org/10.5194/egusphere-egu24-712, 2024.

10:05–10:15
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EGU24-4775
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Highlight
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On-site presentation
First results from the radiation belt monitors onboard the 6U CubeSat X-Ray Observatory NinjaSat 
Yo Kato and the NinjaSat Team

NinjaSat, a 6U CubeSat-sized (30 cm x 20 cm x 10 cm) X-ray observation satellite, was launched into a low Earth orbit at an altitude of 550 km in November 2023. NinjaSat is equipped with two 1U CubeSat-sized (10 cm x 10 cm x 10 cm) gas X-ray detectors (GMC) as primary detectors for astronomical observations of bright X-ray sources such as neutron stars and black holes. Initial operations of NinjaSat have been underway since January 2024.

NinjaSat is also equipped with two radiation belt monitors (RBM) as sub-detectors to protect the GMCs from discharges in the gas cells potentially caused by excessive amount of incident charged particles. NinjaSat RBM uses a 9 mm x 9 mm Si-PIN photodiode to detect any increase in the count rate of either protons or electrons by exploiting the difference in the sensor's response to protons and electrons, and sends alert signals to GMCs which help ramping down high voltage applied to gas cells in the region of high charged particle rates. NinjaSat RBM is approximately 6% of the size of a 1U CubeSat in volume and weighs only 70 grams. Because NinjaSat RBM uses inexpensive, commercially available sensors and operates on an internal board independent of the primary detectors, it can be installed on other small satellites which need to monitor surrounding charged particle environment with relatively few development resources.

Since NinjaSat will operate in a sun-synchronous orbit, a global map of charged particles can be obtained. We will present the development of NinjaSat RBM and the first results of charged particle maps in the radiation belt obtained during the initial operational period of NinjaSat.

How to cite: Kato, Y. and the NinjaSat Team: First results from the radiation belt monitors onboard the 6U CubeSat X-Ray Observatory NinjaSat, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4775, https://doi.org/10.5194/egusphere-egu24-4775, 2024.

Coffee break
Chairpersons: C.-Philippe Escoubet, Yulia Bogdanova
10:45–11:05
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EGU24-11903
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solicited
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Highlight
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On-site presentation
The ESA M7 candidate mission Plasma Observatory. 
Maria Federica Marcucci and Alessandro Retinò and the Plasma Observatory team

Particle energization and transport of energy are key open problems of space plasma physics. Their comprehension has implications on research fields that span from space weather to the understanding of the farthest astrophysical plasmas. The Magnetospheric System is the complex and highly dynamic plasma environment where the strongest energization and energy transport occurs in near-Earth space.  Previous multi-point observations from missions such as ESA/Cluster and NASA/MMS have greatly improved our understanding of plasma processes and evidenced the fundamental role of cross-scales coupling. Simultaneous measurements at both large, fluid and small, kinetic scales are required to resolve scale coupling and ultimately fully understand plasma energization and energy transport processes. Such measurements are currently not available. Here we present the Plasma Observatory (PO) multi-scale mission concept tailored to study plasma energization and energy transport in the Earth's Magnetospheric System through simultaneous measurements at both fluid and ion scales. These are the scales at which the largest amount of electromagnetic energy is converted into energized particles and energy is transported. PO baseline mission includes one mothercraft (MSC) and six identical smallsat daughtercraft (DSC) in two nested tetrahedra formation with MSC at the common vertex for both tetrahedra. PO orbit is an HEO 8x18 RE orbit, covering all the key regions of the Magnetospheric System including the foreshock, the bow shock, the magnetosheath, the magnetopause, the magnetotail current sheet, and the transition region. Along the orbit, the separations between the spacecraft range from fluid (5000 km) to ion (30 km) scales. The MSC payload provides a complete characterization of electromagnetic fields and particles in a single point with time resolution sufficient to resolve kinetic physics at sub-ion scales (for both protons and heavy ions). The DSCs have identical payload, simpler than the MSC payload, yet giving a full characterization of the plasma at the ion and fluid scales. PO is the next logical step after Cluster and MMS and will allow us to resolve for the first time scale coupling in  the Earth's Magnetospheric System, leading to transformative advances in the field of space plasma physics. Plasma Observatory  is one of the three ESA M7 candidates, which have been selected in November 2023 for a competitive Phase A with a mission selection planned in 2026 and launch in 2037.

How to cite: Marcucci, M. F. and Retinò, A. and the Plasma Observatory team: The ESA M7 candidate mission Plasma Observatory., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11903, https://doi.org/10.5194/egusphere-egu24-11903, 2024.

11:05–11:15
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EGU24-14405
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Highlight
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On-site presentation
Global-Scale Magnetosphere Convection Driven by Dayside Magnetic Reconnection 
Lei Dai, Minghui Zhu, Yong Ren, Walter Gonzalez, Chi Wang, David Sibeck, Andrey Samsonov, Philippe Escoubet, Binbin Tang, Jiaojiao Zhang, and Graziella Branduardi-Raymont

Plasma convection on a global scale is a fundamental feature of planetary magnetosphere. The Dungey cycle explains that steady-state convection within the closed part of the magnetosphere relies on magnetic reconnection in the nightside magnetospheric tail. Nevertheless, time-dependent models of the Dungey cycle suggest an alternative scenario where magnetospheric convection can be solely driven by dayside magnetic reconnection. In this study, we provide direct evidence supporting the scenario of dayside-driven magnetosphere convection. The driving process is closely connected to the evolution of Region 1 and Region 2 field-aligned currents. Our global simulations demonstrate that intensified magnetospheric convection and field-aligned currents progress from the dayside to the nightside within 10-20 minutes, following a southward turning of the interplanetary magnetic field. Observational data within this short timescale also reveal enhancements in both magnetosphere convection and the ionosphere's two-cell convection. These findings provide insights into the mechanisms driving planetary magnetosphere convection, with implications for the upcoming Solar-Wind-Magnetosphere-Ionosphere Link Explorer (SMILE) mission.

How to cite: Dai, L., Zhu, M., Ren, Y., Gonzalez, W., Wang, C., Sibeck, D., Samsonov, A., Escoubet, P., Tang, B., Zhang, J., and Branduardi-Raymont, G.: Global-Scale Magnetosphere Convection Driven by Dayside Magnetic Reconnection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14405, https://doi.org/10.5194/egusphere-egu24-14405, 2024.

11:15–11:25
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EGU24-16125
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On-site presentation
Kelvin-Helmholtz Instability associated with reconnection and Ultra Low Frequency Waves at the ground 
Elena Kronberg, Jamie Gorman, Katariina Nykyri, Artem Smirnov, Jesper Gjerloev, Elena Grigorenko, Xuanye Ma, Karlheinz Trattner, and Matt Friel

The Kelvin-Helmholtz instability (KHI) and its effects related to the transfer of energy and mass from the solar wind into the magnetic environment of the Earth remain an important focus of magnetospheric physics. One such effect is the generation of Pc4-Pc5 ultra low frequency (ULF) waves at the ground. On July 3, 2007 at ∼0500 magnetic local time the Cluster space mission encountered Pc4 frequency Kelvin-Helmholtz waves (KHWs). Typically, KHI is thought to occur during the northward polarity of the interplanetary magnetic field and at low latitudes, however, the event occurred during a period of the southward polarity  according to the OMNI data and THEMIS observations at the subsolar point and at the high latitude magnetopause. Several of the KHI vortices were associated with magnetic field reconnection. Global magnetohydrodynamic simulation of the event confirmed the generation of KHWs at the magnetopause. The observed KHWs associated with reconnection coincided with recorded ULF waves at the ground whose properties suggest that they were driven by those waves. 

How to cite: Kronberg, E., Gorman, J., Nykyri, K., Smirnov, A., Gjerloev, J., Grigorenko, E., Ma, X., Trattner, K., and Friel, M.: Kelvin-Helmholtz Instability associated with reconnection and Ultra Low Frequency Waves at the ground, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16125, https://doi.org/10.5194/egusphere-egu24-16125, 2024.

11:25–11:35
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EGU24-5073
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ECS
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On-site presentation
On the Prevalence of Lower-Hybrid Wave-Induced Electron-Scale Current Sheets related to Kelvin-Helmholtz Vortices during Southward IMF 
Kevin Alexander Blasl, Adriana Settino, Rumi Nakamura, Takuma Nakamura, Hiroshi Hasegawa, Zoltan Vörös, Martin Hosner, Evgeny Panov, Daniel Schmid, Martin Volwerk, Owen Wyn Roberts, and Yi-Hsin Liu

Numerous spacecraft missions, theories and numerical modelling have studied the Kelvin-Helmholtz instability (KHI) excited at the Earth’s magnetopause at different scales. Important insights into particle transport and mixing as well as energy conversion related to the KHI were obtained from these studies and linked to processes such as magnetic reconnection and plasma turbulence.

Recently, Blasl et al. (2022, 2023) and Nakamura et al. (2022 a, b) reported the first observations of the KHI during southward Interplanetary Magnetic Field (IMF) conditions from the Magnetospheric Multiscale (MMS) mission together with fully-kinetic Particle-In-Cell simulations designed for this event. The unprecedented resolution of the MMS mission together with large-scale kinetic simulation runs enabled a multi-scale study of the KHI. Their results showed the onset and evolution of secondary instabilities such as the Rayleigh-Taylor Instability responsible for globally deforming the vortex structures as well as the Lower-Hybrid Drift Instability (LHDI) leading to plasma mixing along the spine region of the vortices. Additionally, at 1 out of the 11 KH wave crossings they reported the observation of an electron-scale reconnecting current sheet at the interface between this mixing region and the magnetospheric plasma, as suggested by simulation results.

In this study, we revisit this previously reported MMS KH event during southward IMF and study the remaining 10 vortex structures in detail. Especially, we will characterize the signatures of LHDI-induced plasma mixing from both simulations and observations at different evolutionary stages and discuss the prevalence and signatures of small-scale current sheets at these vortex structures. First results suggest the coexistence of vortex structures at different evolutionary stages in this KH event, which will be discussed in detail. A short discussion on the influence of the IMF on this mechanism will be given at the end of the presentation.

How to cite: Blasl, K. A., Settino, A., Nakamura, R., Nakamura, T., Hasegawa, H., Vörös, Z., Hosner, M., Panov, E., Schmid, D., Volwerk, M., Roberts, O. W., and Liu, Y.-H.: On the Prevalence of Lower-Hybrid Wave-Induced Electron-Scale Current Sheets related to Kelvin-Helmholtz Vortices during Southward IMF, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5073, https://doi.org/10.5194/egusphere-egu24-5073, 2024.

11:35–11:45
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EGU24-16339
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ECS
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On-site presentation
A Radial Standing Pc5-6 Wave and Its Energy Coupling With Field Line Resonance Within the Dusk-Sector Magnetosphere 
Zhou Yi-Jia, He Fei, Zhang Xiao-Xin, Martin Archer, Lin Yu, Ma Han, Tian An-Min, Yao Zhong-Hua, Wei Yong, Ni Binbin, Liu Wenlong, Zong Qiu-Gang, and Pu Zu-Yin
Global ultra-low frequency (ULF) oscillations are believed to play a significant role in the mass,
energy, and momentum transport within the Earth's magnetosphere. In this letter, we observe a ∼1.2 mHz
radial standing wave in the dusk-sector magnetosphere accompanied by the field line resonance (FLR) on 16
July 2017. The frequency estimation from the simple box model also confirms the radial standing wave. The
essential characteristics of FLR are concurrently identified at the dusk-sector magnetosphere and the conjugated
ground location. Further, the radial standing wave dissipates energy into upper atmosphere to enhance the
local aurora by coupling itself to the FLR. The magnetospheric dominant 1.2/1.1 mHz ULF waves plausibly
correspond well with the discrete ∼1 mHz magnetosheath ion dynamic pressure/velocity oscillation, suggesting
this radial standing wave and FLR in the flank magnetosphere may be triggered by the solar-wind and/or
magnetosheath dynamic pressure/velocity fluctuations.

How to cite: Yi-Jia, Z., Fei, H., Xiao-Xin, Z., Archer, M., Yu, L., Han, M., An-Min, T., Zhong-Hua, Y., Yong, W., Binbin, N., Wenlong, L., Qiu-Gang, Z., and Zu-Yin, P.: A Radial Standing Pc5-6 Wave and Its Energy Coupling With Field Line Resonance Within the Dusk-Sector Magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16339, https://doi.org/10.5194/egusphere-egu24-16339, 2024.

11:45–11:55
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EGU24-2058
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Highlight
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On-site presentation
Magnetospheric Auroral Asymmetry eXplorer: observing the auroral to uncover how energy flows in space - A Phase A SMEX Mission concept 
Alexa Halford, Michael Liemohn, Aaron Ridley, Daniel Welling, Thomas Immel, Hyunju Connor, Anna DeJong, Gerard Fasel, Christine Gabrielse, Katherine Garcia-Sage, Brian Harding, Emma Spanswick, Shasha Zoe, and Elizabeth MacDonald

The Magnetospheric Auroral Asymmetry Explorer (MAAX) mission concept makes a significant leap in determining how magnetosphere-ionosphere electrodynamic coupling regulates multi-scale energy flow through the near-Earth space environment. Recently selected for a competitive Phase A mission concept study for NASA's Heliophysics Small Explorer program, MAAX accomplishes this by:

  • Understanding how seasons and tilt of the magnetic field regulate energy flow from the solar wind through the geospace system.
  • Discovering how the auroral background conductance governs the formation, evolution, and interhemispheric asymmetries of nightside meso-scale auroral features.
  • Determining how the time-dependent magnetospheric energy flow controls multi-scale auroral dynamics.

The solar wind energy enters the magnetosphere mainly through dayside reconnection. It is stored in the magnetospheric lobes, released in the tail, converted to plasma thermal and kinetic energies. The dynamic processes in the nightside magnetosphere map from the magnetosphere to the ionosphere, resulting in auroral structures. Observations of the aurora have been used as a window to probe and understand these dynamics even beyond the Earth system. The magnetic field lines in which the aurora occurs thread through both hemispheres. Traditionally, auroral observations from one hemisphere are assumed to be conjugate, while limited observations suggest this may not always be applicable. Thus, we can only understand some of the processes that control energy flow through the system from one hemisphere. With observations in both hemispheres, we gain a deeper understanding of the dynamics of this integrated system. MAAX comprises two observatories in circular polar orbits at 20,850 km altitude to view the two auroral ovals. Each satellite carries a high-heritage UV imager that operates poleward of +/-35° latitude. For the mission's 1st year, the observatories are spaced at 90° to allow continuous coverage of each oval with a 6-hour duty cycle. This phase also provides intervals in which both view the same hemisphere or the exact longitude but different hemispheres. For the 2nd year of the mission, the observatories are spaced at 180° to have simultaneous complete viewing of both auroral ovals with a 4.5 hr/1.5 hr on/off duty cycle. Discussed here are the scientific motivations of the mission concepts.

How to cite: Halford, A., Liemohn, M., Ridley, A., Welling, D., Immel, T., Connor, H., DeJong, A., Fasel, G., Gabrielse, C., Garcia-Sage, K., Harding, B., Spanswick, E., Zoe, S., and MacDonald, E.: Magnetospheric Auroral Asymmetry eXplorer: observing the auroral to uncover how energy flows in space - A Phase A SMEX Mission concept, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2058, https://doi.org/10.5194/egusphere-egu24-2058, 2024.

11:55–12:05
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EGU24-15192
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On-site presentation
Examining Interhemispheric Properties of the Cusp 
Kevin Pham, William Lotko, Ying Zou, Binzheng Zhang, Roger Varney, and Pauline Dredger

The magnetospheric cusp is a narrow region of geospace where the solar wind has direct access to the ionosphere and thermosphere. The low-altitude projection of the cusp is a site of concentrated energy dissipation, which leads to extraordinary thermospheric upwelling and prodigious outflows of ionospheric ions into the magnetosphere.  Although interhemispheric and seasonal differences in cusp morphology and properties are recognized, statistical empirical identifications and models do not properly capture important temporal and spatial features of the cusp.  We have analyzed cusp location, size and energization, and dynamics, using different identification methods applied to the Multiscale Atmosphere Geospace Environment (MAGE) global simulation model.  Interhemispheric differences are considered for a variety of seasonal and solar wind conditions.  Preliminary results indicate that under strong IMF By conditions, commonly used cusp identification methods do not agree and are associated with the direct-entry and Alfvenic cusps not being collated.  Furthermore, we find that the simulated cusp is not discernable in one hemisphere but is pronounced in the other hemisphere.  We explore under what conditions this occurs.

How to cite: Pham, K., Lotko, W., Zou, Y., Zhang, B., Varney, R., and Dredger, P.: Examining Interhemispheric Properties of the Cusp, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15192, https://doi.org/10.5194/egusphere-egu24-15192, 2024.

12:05–12:15
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EGU24-10383
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ECS
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Highlight
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On-site presentation
In Situ Observations of Interaction Between the Closed Magnetic Field of Earth’s Transpolar Auroral Arcs and the Interplanetary Magnetic Field 
Nawapat Kaweeyanun and Robert Fear

Transpolar arcs (TPAs) are extensions of auroral emission poleward beyond the main ovals, forming partial or complete bisections known as ‘theta’ auroras. A prominent hypothesis suggests that a TPA occurs through stagnation of magneto-plasma returning from Earth’s magnetotail under northward interplanetary magnetic field (IMF), resulting in a ‘wedge’ of closed magnetic field lines in the open polar cap on which particles resemble those in the nightside equatorial plasma sheet. It has been proposed that a TPA’s closed-field lines may reach sufficiently high latitude to magnetically reconnect with the IMF at the lobe magnetopause, leading to observed coincidence of the TPA and a cusp spot. Using conjugate data from Cluster, Imager for Magnetopause-to-Aurora Global Exploration (IMAGE), Special Sensor Ultraviolet Spectrographic Imager (SSUSI), and other instruments, we demonstrate at least one case study of potential first in situ detection of TPA-IMF magnetic reconnection with magneto-plasma and visual aurora evidence, and several further instances of particles on closed magnetic field lines near the lobe magnetopause. Pending affirmative analysis, the existence of TPA-IMF reconnection events will not only further support the ‘wedge’ TPA formation hypothesis, but also indicate that lobe reconnection can open topologically closed nightside magnetic field lines, introducing new polar cap dynamics under northward IMF.

How to cite: Kaweeyanun, N. and Fear, R.: In Situ Observations of Interaction Between the Closed Magnetic Field of Earth’s Transpolar Auroral Arcs and the Interplanetary Magnetic Field, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10383, https://doi.org/10.5194/egusphere-egu24-10383, 2024.

12:15–12:25
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EGU24-18105
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On-site presentation
Dual-lobe reconnection, horse-collar auroras, and cusp-aligned arcs
(withdrawn)
Steve Milan, Michaela Mooney, Gemma Bower, Larry Paxton, Sarah Vines, and Marc Hairston
12:25–12:30
Discussion
Lunch break
Chairpersons: Andrey Samsonov, Tianran Sun
14:00–14:20
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EGU24-6504
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solicited
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Highlight
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Virtual presentation
Cross-Scale Processes of Magnetic Reconnection 
Kyoung-joo Hwang, Rumi Nakamura, Jonathan Eastwood, Stephen Fuselier, Hiroshi Hasegawa, Takuma Nakamura, Benoit Lavraud, Kyunghwan Dokgo, Drew Turner, Robert Ergun, and Patricia Reiff

Various physical processes in association with magnetic reconnection occur over multiple scales from the microscopic to macroscopic scale lengths. This presentation reviews multi-scale and cross-scale aspects of magnetic reconnection revealed in the near-Earth space beyond the general global-scale features and magnetospheric circulation organized by the Dungey Cycle. Significant and novel advancements recently reported, in particular, since the launch of the Magnetospheric Multi-scale mission (MMS), are highlighted being categorized into different locations with different magnetic topologies. These potentially paradigm-shifting findings include shock and foreshock transient driven reconnection, magnetosheath turbulent reconnection, flow shear driven reconnection, multiple X-line structures generated in the dayside/flankside/nightside magnetospheric current sheets, development and evolution of reconnection-driven structures such as flux transfer events, flux ropes, and dipolarization fronts, and their interactions with ambient plasmas. We emphasize key aspects of kinetic processes leading to multi-scale structures and bringing large-scale impacts of magnetic reconnection as discovered in the geospace environment. These key features can be relevant and applicable to understanding other heliospheric and astrophysical systems.

How to cite: Hwang, K., Nakamura, R., Eastwood, J., Fuselier, S., Hasegawa, H., Nakamura, T., Lavraud, B., Dokgo, K., Turner, D., Ergun, R., and Reiff, P.: Cross-Scale Processes of Magnetic Reconnection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6504, https://doi.org/10.5194/egusphere-egu24-6504, 2024.

14:20–14:30
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EGU24-12236
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Highlight
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On-site presentation
A Particle-in-Cell Simulation of Ion and Electron Dynamics from Tail Reconnection to the Inner Magnetosphere 
Raymond Walker, Mostafa El-Alaoui, Liutauras Rusaitis, Giovanni Lapenta, Nicole Echterling, and David Schriver

We have used a PIC simulation combined with a global MHD simulation to model the interaction between magnetotail plasma from reconnection and inner magnetosphere region. The PIC simulation extended from the solar wind outside of the bow shock to beyond the reconnection region in the tail. The initial simulation was carried out with nominal solar wind parameters and southward IMF. A partial ring current and diamagnetic current formed in the PIC simulation.  Initially, the partial ring current formed by drift of the particles loaded into the PIC simulation. However, the PIC run lasted ~2 m and by the end of the calculation particles from tail reconnection had reached the inner magnetosphere and contributed to the partial ring current.  The sources of the particles to the inner magnetosphere are bursty bulk flows (BBFs) that originate from a complex pattern of reconnection in the near-Earth magnetotail at about XGSM=-25- to -30 RE. After the particles jet away from the initial reconnection site, they can undergo further acceleration at secondary reconnection sites. Electrons jet away from the reconnection much faster than the ions setting up an ambipolar electric field allowing the ions to catch up after 4-14 di (ion inertial lengths). The initial energy flux in the BBFs is mainly in the form of kinetic energy flux from the jetting particles, but as they move earthward the energy flux changes to enthalpy flux. The energy flux in the simulated ring current is primarily in the form of enthalpy flux. The power delivered from the tail reconnection in the simulation to the inner magnetosphere (~6X1011 W) is consistent with observations.

 

How to cite: Walker, R., El-Alaoui, M., Rusaitis, L., Lapenta, G., Echterling, N., and Schriver, D.: A Particle-in-Cell Simulation of Ion and Electron Dynamics from Tail Reconnection to the Inner Magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12236, https://doi.org/10.5194/egusphere-egu24-12236, 2024.

14:30–14:40
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EGU24-20221
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On-site presentation
Transformations of the Electromagnetic Field in Different Frames of Reference and the Applications 
Chao Shen and Yong Ji

The transformation of the electromagnetic fields in different frames of reference (wether inertial reference frames or non-inertial reference frames) is the problem frequently met during the electromagnetic measurements in space and the relative analysis. For example, to draw the values of the electromagnetic fields in spacecraft comoving reference frame from the electromagnetic fields measured in the spacecraft rotational reference frame with a reasonable accuracy. Another example is the calculation of the charge density based on the four-point electrostatic field observations of MMS; the present analysis is not very satisfactory and there is still no rigid evaluation on the method applied. However, it is not easy to find a plain and rigid evaluation on the transformation formulas used. In this research, a systematic theoretic investigation has been performed, the universal formulas for the transformation are given and further applied to two actual situations successfully. For space plasmas, the relative velocities of the structures are generally very low and always much less than the speed of light in vacuum, so that the Galillia transformations are applicable. In this study, the Galillia transformations of the electromagnetic fields, the electric potential and magnetic vector potential, and the charge density and current density in different reference frames (wether inertial reference frames or non-inertial reference frames) have been presented and the respective errors are given. The results can find wide applications in space physics. At first, the general formula for the rotational potential of the planets are obtained. Secondly, by using the yielded theoretical results, a strict verification on the deduction of the charge density based on MMS electrostatic fields measurements has been made. It is found that, the Poisson equation is valid because the Coulomb gauge can be used for low-speed motions, and it is enough to draw the charge density from the MMS electrostatic fields measurements with a first order relative error. 

How to cite: Shen, C. and Ji, Y.: Transformations of the Electromagnetic Field in Different Frames of Reference and the Applications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20221, https://doi.org/10.5194/egusphere-egu24-20221, 2024.

14:40–14:50
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EGU24-13795
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ECS
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On-site presentation
Mid-latitude Electric Field Response during Isolated Substorms: Effects of SCW Location and Shielding 
Moe Hayashi, Akimasa Yoshikawa, and Akiko Fujimoto

The substorm current wedge (SCW) characterizes the current system during substorms. The high-latitude electric field associated with the SCW penetrates toward mid- and low-latitudes. Various case studies have reported that the penetration electric field becomes stronger with the region-1 (R1) sense SCW, while the region-2 (R2) sense SCW shields the electric field. However, the statistical properties of the penetration electric field remain unclear. Moreover, the detailed relationship between the SCW's location and the electric field has been seldom examined. In this study, using substorms that occurred from 2010 to 2013, we evaluated the effects of shielding and statistically investigated its impact on the mid-latitude electric field using the following methods. We determined the temporal development of the SCW structure from the north-south and east-west components of the ground magnetic field and evaluated the effect of shielding, based on the magnitude of the R1/R2 SCW by AMPARE. We then analyzed the relation between these and the direction and magnitude of the electric field from Kyushu University’s FM-CW radar at midlatitude. The results show that, when the R1 SCW is more dominant, a westward electric field is observed in the center of the SCW and an eastward electric field is observed on the outside. The magnitude of those electric fields depends on the scale of the substorms. When the R2 SCW is comparable to the R1 SCW, these electric fields are shielded or overshielded, resulting in a smaller magnitude or opposite direction of the electric field. These findings suggest that the strength of the R2 SCW and the location of the SCW are the major contributors to the penetrating electric field.

How to cite: Hayashi, M., Yoshikawa, A., and Fujimoto, A.: Mid-latitude Electric Field Response during Isolated Substorms: Effects of SCW Location and Shielding, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13795, https://doi.org/10.5194/egusphere-egu24-13795, 2024.

14:50–15:00
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EGU24-13578
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ECS
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Highlight
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Virtual presentation
Evaluating the magnetic and plasma flux transport in the plasma sheet during geomagnetic storms using MMS 
Savvas Raptis, Slava Merkin, Shin Ohtani, and Matina Gkioulidou

During geomagnetic storms, the nightside of Earth’s magnetosphere experiences significant disturbances, featuring various phenomena that interact with one another. These include enhanced convection and particle injections influencing ring current development, alongside mesoscale structures like bursty bulk flows (BBFs) and dipolarization fronts, which play roles in plasma and magnetic flux transport within the plasma sheet. However, their specific functions during storms are not fully comprehended.

In our work, we evaluate the transport of magnetic and plasma flux in the plasma sheet region using data obtained from NASA’s Magnetosphere Multiscale (MMS) mission. Leveraging MMS's extensive measurements from the plasma sheet, a statistical analysis is conducted based on nearly 200,000 data points (at 4.5-second resolution) obtained from the Fast Plasma Investigator (FPI) during quiet and disturbed geomagnetic periods.

The statistical examination primarily focuses on how different properties describing convection in the plasma sheet vary across distinct phases of storms (main and recovery) and at various distances from Earth. Furthermore, we compare our results with these obtained by prior research from other missions. Additionally, we assess whether variations in instrumental capabilities, such as time resolution and energy range among different instruments on MMS, could influence the statistical outcomes

How to cite: Raptis, S., Merkin, S., Ohtani, S., and Gkioulidou, M.: Evaluating the magnetic and plasma flux transport in the plasma sheet during geomagnetic storms using MMS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13578, https://doi.org/10.5194/egusphere-egu24-13578, 2024.

15:00–15:10
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EGU24-16718
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ECS
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Virtual presentation
Remote, long-term auroral kilometric radiation observations as a geomagnetic indicator of substorm onset 
James Waters, Laurent Lamy, and John Coxon

Auroral kilometric radiation (AKR) is a cyclotron maser instability generated radio emission that occurs in the region above the auroral oval; the observed intensity increases with the growth rate of the instability, indicating an active source region and the presence of accelerated electrons, while the emission frequency is inversely proportional to the altitude of a source along a field line. Remote observations can thus provide a direct insight into the spatial development of the primary coupling region between the magnetosphere and ionosphere during energetic phenomena. During substorms in particular, the auroral acceleration region has been shown to increase in altitude and increase the low-frequency power of the AKR spectrum, particularly towards dusk (Morioka et al. 2007, Waters et al. 2022). However, AKR is beamed anisotropically, which makes it difficult to observe global variability of the emission when a spacecraft is not in an ideal position, namely at dayside local times.

With an automatic extraction of AKR observations from the Wind spacecraft, we have access to nearly 30 years of data from a variety of viewing positions. The latest 20 years of observations are made from the  dayside, near L1. To evaluate the efficacy of the AKR observations as an indicator of substorm dynamics and further constrain the visibility effects, we compare AKR bursts from Wind (Fogg, Jackman, Waters et al. 2022) to a published list of substorm events derived from the SuperMAG magnetometer network. We calculate the binary classification statistics in four local time sectors with more than 10 years of AKR observation. When evaluated over a 2 hour window, AKR bursts observed from the nightside and duskside have a good (> 0.6) recall of substorm events, while the duskside observations have a more favourable false alarm probability (< 0.4). Dayside observations have a high miss rate (~0.8), but a high specificity (> 0.9), thus exhibiting a reliable proxy for substorm activity. Observations from all local time sectors except the nightside have positive forecast skill as determined by the Heidke skill score. Occurrence distributions of AKR burst frequencies from each local time sector and event group highlight the components present in each local time sector. This work lays the foundations for further parameterisation of the visibility of AKR sources at different locations within the inner magnetosphere by Wind when observing from L1, where the effects of the frequency, magnetic local time and magnetic latitude of the source can be examined more finely. Such work is useful for providing context for past AKR observations, as well as for the interpretation of future radio observations (with the JUICE flyby of Earth, for example), observation scheduling or planning of future missions.

How to cite: Waters, J., Lamy, L., and Coxon, J.: Remote, long-term auroral kilometric radiation observations as a geomagnetic indicator of substorm onset, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16718, https://doi.org/10.5194/egusphere-egu24-16718, 2024.

15:10–15:20
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EGU24-4316
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Highlight
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On-site presentation
Exploring Magnetospheric Substorm Avalanche Dynamics: on Crackling Noise Nature  
Giuseppe Consolini and Paola De Michelis

The dynamics of the Earth's magnetosphere/ionosphere system is remarkably complex, particularly in response to changes of the solar wind and interplanetary conditions. This interplay between the Earth's magnetic field and the solar wind generates a highly complex dynamics. The interaction between the interplanetary medium and the Earth's magnetosphere triggers significant changes within the magnetosphere/ionosphere system. These alterations can lead to various phenomena, including magnetospheric substorms, which exhibit an avalanche dynamics and scale-free energy dissipation. This complex behavior resembles crackling noise phenomena observed in certain physical systems. By examining the scaling properties of auroral electrojet AL-index bursts during these substorms, we have identified similarities with crackling noise in front propagation models. Furthermore, our investigation has unveiled a scaling function describing the avalanche profile of the AL-index, shedding light on the underlying mechanisms governing these bursty dynamics. These findings significantly contribute to our understanding of magnetospheric plasma sheet dynamics and the mechanisms behind the magnetospheric substorms. By linking the scale-free characteristics of these bursts to crackling noise behavior, we gain valuable insights into the underlying physics governing these complex phenomena within Earth's magnetosphere/ionosphere system.

How to cite: Consolini, G. and De Michelis, P.: Exploring Magnetospheric Substorm Avalanche Dynamics: on Crackling Noise Nature , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4316, https://doi.org/10.5194/egusphere-egu24-4316, 2024.

15:20–15:30
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EGU24-1994
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ECS
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On-site presentation
Flapping Motion Configurations of Geomagnetotail Current Sheet 
Peng Shao and Chao Shen

We explore the geometry of the flapping motion of geomagnetotail current sheet with the magnetic measurements of the Cluster (constellation) using a newly developed technique. The principal curvatures and directions of the surfaces of the flapping current sheet are successfully deduced by the normal field analysis (NFA). Results show that the directions with the minimum curvature of surfaces of flapping motion are approximately along the Sun-Earth line, while the ones with maximum curvature are mostly in the dawn-dusk plane. It is confirmed that the tail flapping motion is a wave arising in the Y-Z plane, but not bend along the Sun-Earth line. Furthermore, our calculations reveal that the maximum curvature radius of the flapping current sheet's surface along the X-axis is on the order of several dozen Earth radii. This implies that the flapping motion extends spatially over a range from several to a dozen Earth radii along the Sun-Earth direction.

How to cite: Shao, P. and Shen, C.: Flapping Motion Configurations of Geomagnetotail Current Sheet, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1994, https://doi.org/10.5194/egusphere-egu24-1994, 2024.

15:30–15:40
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EGU24-17375
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ECS
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On-site presentation
Impact of Interplanetary Coronal Mass Ejections (ICME) on the geomagnetic tail from THEMIS observations 
Soboh Alqeeq, Dominique Fontaine, Olivier Le Contel, Mojtaba Akhavan-Tafti, Emanuele Cazzola, and Tsige Atilaw

We focus on a well-defined interplanetary coronal mass ejection (ICME) with a dynamic pressure Pdyn > 20 nPa, in December 2015. ACE observations and OMNI data allowed to identify ahead of Earth the expected features with shock and sheath regions preceding a magnetic cloud. This ICME triggered a storm in the magnetosphere with a storm sudden commencement (SSC) phase (SYM‐H ~ +50 nT) followed by a growth phase (SYM‐H < −150 nT at the minimum) and a long recovery phase lasting several days.

We investigate the global impact of this ICME on the Earth's magnetotail from observations by the NASA mission THEMIS. Indeed we estimate the total pressure exerted on the magnetotail current sheet. We find that the current sheet is compressed to ~ >2nP in the main phase, i.e. 4 times more than in the quiet phase before the event. In contrast, the pressure gradually decreases in the recovery phase and approximately comes back towards quiet phase values. According to the tracking of magnetic field lines using the Tsyganenko T96 magnetic field model, the current sheet appears stretched right from the SSC phase, and even more than during the main phase, before returning progressively to a shape comparable to the quiet phase. We quantify and discuss these effects to provide a more precise description of the magnetospheric geomagnetic activity during solar events.

How to cite: Alqeeq, S., Fontaine, D., Le Contel, O., Akhavan-Tafti, M., Cazzola, E., and Atilaw, T.: Impact of Interplanetary Coronal Mass Ejections (ICME) on the geomagnetic tail from THEMIS observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17375, https://doi.org/10.5194/egusphere-egu24-17375, 2024.

15:40–15:45
Discussion

Posters on site: Mon, 15 Apr, 16:15–18:00 | Hall X3

Display time: Mon, 15 Apr, 14:00–18:00
Chairpersons: Yulia Bogdanova, Andrey Samsonov
X3.18
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EGU24-21617
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ECS
Supervised Machine Learning Algorithm to Classify Interplanetary Directional Discontinuities 
Daniel Dumitru, Costel Munteanu, Catalin Negrea, and Marius Echim

Directional discontinuities (DDs) are defined as abrupt changes of the magnetic field orientation. We use observations from ESA’s Cluster mission to compile a database of 4216 events identified in January-April 2007 and 5194 events from January-April 2008. Localized time-scale images depicting angular changes are created for each event, and a preliminary classification algorithm is designed to distinguish between: simple - isolated events, and complex - multiple overlapping events. In 2007, 1806 events are pre-classified as simple, and 2410 as complex; in 2008, 1997 events are simple, and 3197 are complex.  A supervised machine learning approach is used to recognize and predict these events. Two models are trained: one for 2007, which is used to predict the results in 2008, and vice versa for 2008. To validate our results, we investigate the discontinuity occurrence rate as a function of spacecraft location. When the spacecraft is in the solar wind, we find an occurrence rate of similar to 2 DDs per hour and a 50/50% ratio of simple/complex events. When the spacecraft is in the Earth's magnetosheath, we find that the total occurrence rate remains around 2 DDs/hr, but the ratio of simple/complex events changes to similar to 25/75%. This implies that about half of the simple events observed in the solar wind are classified as complex when observed in the magnetosheath. This demonstrates that our classification scheme can provide meaningful insights, and thus be relevant for future studies on interplanetary discontinuities. Parts of this research were published in AGU Earth and Space Science: Dumitru and Munteanu (2023), https://doi.org/10.1029/2023EA002960.



How to cite: Dumitru, D., Munteanu, C., Negrea, C., and Echim, M.: Supervised Machine Learning Algorithm to Classify Interplanetary Directional Discontinuities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21617, https://doi.org/10.5194/egusphere-egu24-21617, 2024.

X3.19
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EGU24-9845
On the influence of solar wind turbulence on the Earth's foreshock dynamics 
Francesco Pucci, Etienne Behar, Pierre Henri, Cyril Simon Wedlund, Luis Preisser, Giulio Ballerini, and Francesco Califano

We present the results of two numerical simulations of the interaction between the solar wind and a planetary Earth-like magnetosphere. We use the hybrid particle-in-cell (PIC) code Menura, which allows for injecting a turbulent solar wind [1]. The two numerical simulations we present only differ one from the other on the nature of the solar wind, which is laminar in one case and turbulent in the other. Even though we poorly resolve ion scales because of computational constraints, we observe the development of a foreshock in the quasi-parallel shock region formed by kinetic effects due to the presence of reflected particles. 

We focus our analysis on the spatial properties of the reflected ion beams and compare them in the case of laminar and turbulent solar wind. In the laminar case, we observe the presence of fast modes excited by reflected particles and find homogeneous density and temperature of the ion beam in the foreshock region. Instead, in the turbulent case,  we find that fluctuations in the foreshock are not simple fast waves but result from the interaction between solar wind turbulence and reflected particles. We also observe that density and temperature are modulated in space in contrast with the laminar case. We argue that this modulation arises from the complex shape of the magnetic field, in which field line random walk and perpendicular diffusion are enhanced with respect to the laminar case.   


[1] Behar, E., Fatemi, S., Henri, P., & Holmström, M. (2022, May). Menura: a code for simulating the interaction between a turbulent solar wind and solar system bodies. In Annales Geophysicae (Vol. 40, No. 3, pp. 281-297). Copernicus GmbH.

How to cite: Pucci, F., Behar, E., Henri, P., Wedlund, C. S., Preisser, L., Ballerini, G., and Califano, F.: On the influence of solar wind turbulence on the Earth's foreshock dynamics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9845, https://doi.org/10.5194/egusphere-egu24-9845, 2024.

X3.20
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EGU24-16333
Probing the link between interplanetary magnetic field directional changes and bow shock geometry using simultaneous Cluster-MMS observations 
Costel Munteanu, Eliza Teodorescu, Marius Echim, Gabriel Voitcu, Maximilian Teodorescu, Cătălin Negrea, and Daniel Dumitru

We compiled a catalogue of 117 simultaneous Cluster-MMS magnetosheath crossings in 2017-2021 (http://www.spacescience.ro/projects/twister). The catalogue includes estimates of bow shock orientation for each event. Assuming that the bow shock normal direction does not change significantly during the magnetosheath crossing duration, we estimate the time evolution of θBn as the angle between the 1-minute time-resolution OMNI interplanetary magnetic field (IMF) and the estimated bow shock normal, and we calculate percentages of quasi-perpendicular (45°< θBn <135°) versus quasi-parallel (0°< θBn <45° or 135°< θBn <180°) bow shock orientations for each magnetosheath crossing. Ideally, if 45°< θBn <135° for the entire set of magnetosheath observations, that crossing would be considered “purely” quasi-perpendicular. Instead, we find that most magnetosheath crossings in our catalogue can be classified as “mixed”, i.e.  the bow shock orientation changes from quasi-perpendicular to quasi-parallel during the event. The assumption that the bow shock normal remains constant, implies that all changes of θBn characterising the mixed events are due to changes of IMF direction. To quantify this, we identify and catalogue IMF directional discontinuities during each event, using the algorithm described in Dumitru and Munteanu (2023) (https://doi.org/10.1029/2023EA002960). We present the results of the discontinuity detection algorithm and we probe the effect/role of IMF directional changes on our estimations of bow shock orientation.

How to cite: Munteanu, C., Teodorescu, E., Echim, M., Voitcu, G., Teodorescu, M., Negrea, C., and Dumitru, D.: Probing the link between interplanetary magnetic field directional changes and bow shock geometry using simultaneous Cluster-MMS observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16333, https://doi.org/10.5194/egusphere-egu24-16333, 2024.

X3.21
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EGU24-8171
Foreshock fluctuation and its behaviors 
Gilbert Pi, Zdenek Nemecek, and Jana Safrankova

The foreshock region is a turbulent area that forms before a quasi-parallel shock. It is caused by the interaction between reflected particles from the bow shock and oncoming waves in the solar wind. Typically, the foreshock is located on the dawn side. However, when the interplanetary magnetic field (IMF) points in a radial or anti-radial direction, the foreshock region will move to the nose of the bow shock, covering almost the entire dayside magnetospheric system. This change triggers various phenomena in the magnetospheric system, such as magnetopause expansion and the generation of foreshock transients like sHFA. Our previous studies have shown that foreshocks behave differently depending on different upstream cone angles. The fluctuation is enhanced when approaching the bow shock with an IMF near the Parker spiral structure, but for radial IMF, it remains almost constant. In this study, we investigate the frequency, polarization, and amplitude of fluctuations for different cone angles to uncover the underlying mechanisms.

How to cite: Pi, G., Nemecek, Z., and Safrankova, J.: Foreshock fluctuation and its behaviors, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8171, https://doi.org/10.5194/egusphere-egu24-8171, 2024.

X3.22
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EGU24-8779
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ECS
Comparing L1 to near-Earth data for magnetosheath jet studies 
Georg Blüthner, Manuela Temmer, and Florian Koller

This study explores large-scale solar wind structures and differences in observations between measurement points at L1 and near Earth. Specifically, we focus on coronal mass ejections (CMEs) and stream interaction regions (SIR) together with their distinct substructures. Our study is based on existing CME/SIR lists of events defined by Koller et al. [2022] in OMNI data. For the given time ranges, we compare timing and appearance for the structures in the solar wind plasma and magnetic field parameters as probed by ACE/Wind, OMNI, and THEMIS. Our approach involves creating a database of identified structures, especially those observed by multiple spacecraft, facilitating statistical analysis. Matrix profiles will be employed to unveil recurring patterns and relationships among the substructures measured at different locations. This research will contribute to a more comprehensive understanding of solar wind dynamics and magnetospheric responses to the specific structures which is especially important for magnetosheath jets which are short-lived pressure enhancements.

How to cite: Blüthner, G., Temmer, M., and Koller, F.: Comparing L1 to near-Earth data for magnetosheath jet studies, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8779, https://doi.org/10.5194/egusphere-egu24-8779, 2024.

X3.23
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EGU24-8704
Connection of the magnetosheath jet-like structures with the foreshock and impact on the magnetopause 
Oleksandr Goncharov, Niki Xirogiannopoulou, Kostiantyn Grygorov, Jana Safrankova, and Zdenek Nemecek

Plasma structures with enhanced dynamic pressure, density or speed are often observed in Earth’s magnetosheath. These structures, known as jets and fast plasmoids, can be registered in the magnetosheath, downstream of both the quasi-perpendicular and quasi-parallel bow shocks Using measurements by the Magnetospheric Multiscale (MMS) spacecraft, Goncharov et al., (2020) showed similarities in the plasma properties of the jets and fast plasmoids. On the other hand, they pointed out that the different magnetic fields inside the structures suggest that the formation mechanisms are not the same. Hybrid simulations by Preisser et al., (2020) have shown differences in the mechanisms of jet and embedded plasmoid formation. Previous studies established that foreshock structures can be a source of the jets (Raptis et al., 2022). Xirogiannopoulou et al. (2023) found that the subsolar foreshock contains several types of structures with enhanced density or/and magnetic field magnitude, like plasmoids, SLAMS and mixed structures. Following the results of Xirogiannopoulou et al. (2023) and Goncharov et al., (2020), we compare our MMS measurements with THEMIS observations. Based on our comparative analysis, we discuss features of jet-like structures, their properties, occurrence, evolution, relation to the foreshock, and impact on the magnetopause.

How to cite: Goncharov, O., Xirogiannopoulou, N., Grygorov, K., Safrankova, J., and Nemecek, Z.: Connection of the magnetosheath jet-like structures with the foreshock and impact on the magnetopause, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8704, https://doi.org/10.5194/egusphere-egu24-8704, 2024.

X3.24
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EGU24-8592
Anomalous flows in the magnetosheath and their relation to the magnetopause motion 
Kostiantyn Grygorov, Oleksandr Goncharov, Jana Šafránková, Zdeněk Němeček, and Jiří Šimůnek

The magnetopause (MP) is a critical boundary dividing the space controlled by the Earth's magnetic field from the solar wind and interplanetary magnetic field (IMF). Its position is mainly influenced by the solar wind dynamic pressure and the north-south IMF component (Bz), which are included in various empirical MP models. However, different transient phenomena, such as hot flow anomalies (HFAs) and magnetosheath jets/plasmoids, generated at the bow shock, can significantly impact the MP, redirecting the plasma flow sunward and triggering a rapid displacement of the local MP in this direction.

We present our preliminary results of case and statistical studies of such transient events, aiming to estimate the contribution of their effect on velocity of MP motion. We also discuss the influence of these structures on the local MP shape and orientation. The statistics reveals favorable upstream solar wind conditions and accompanying local magnetosheath parameters.

How to cite: Grygorov, K., Goncharov, O., Šafránková, J., Němeček, Z., and Šimůnek, J.: Anomalous flows in the magnetosheath and their relation to the magnetopause motion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8592, https://doi.org/10.5194/egusphere-egu24-8592, 2024.

X3.25
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EGU24-6237
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Highlight
SMILE: a new view on the dynamic magnetosphere 
C.-Philippe Escoubet and the The SMILE team

How the solar wind and the Earth's magnetosphere interact, involving kinetic, fluid and global scales processes, is one of the key questions in space plasma physics. In situ instruments on a fleet of solar wind and magnetospheric constellation missions now provide the most detailed observations of Sun-Earth connections over multiple scales, from the smallest of a few kilometres up to the largest of a few 10s of Earth radii. However, we are still unable to fully quantify the global effects of the drivers of such connections, including the conditions that prevail throughout geospace due to the limitations of point measurements. This information is the key missing link for developing a complete understanding of how the Sun gives rise to and controls Earth's plasma environment and space weather. This is where SMILE (Solar wind Magnetosphere Ionosphere Link Explorer) comes in.

SMILE is a novel self-standing mission dedicated to observing the solar wind - magnetosphere coupling via simultaneous in situ solar ion and magnetic field measurements, soft X-ray imaging of the magnetosheath, magnetopause and polar cusps, and UV imaging of the northern hemisphere auroral oval. Remote sensing of the magnetosheath and cusps with soft X-ray imaging is made possible thanks to solar wind charge exchange (SWCX) X-ray emissions known to occur in the vicinity of the Earth's magnetosphere. SMILE is a joint mission between ESA and the Chinese Academy of Sciences (CAS) due for launch in the middle of 2025. SMILE science objectives as well as the latest scientific and technical developments, jointly undertaken by ESA, CAS and the international instrument teams, will be presented. SMILE will be complemented by ground-based observatories, in particular the newly funded Canada Space Agency SMILE Imaging Science project, as well as by theory and simulation investigations. This presentation will be dedicated to Graziella Branduardi-Raymont, SMILE mission Co-proposer and mission Co-PI, who passed away on 3rd November 2023.

How to cite: Escoubet, C.-P. and the The SMILE team: SMILE: a new view on the dynamic magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6237, https://doi.org/10.5194/egusphere-egu24-6237, 2024.

X3.26
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EGU24-13469
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Highlight
The Special Issue on Modeling and Data Analysis Methods for the SMILE mission 
Tianran Sun, Hyunju Connor, and Andrey Samsonov

The SMILE (Solar wind Magnetosphere Ionosphere Link Explorer) mission (http://www.nssc.cas.cn/smile/) is a scientific space mission, jointly supported by the European Space Agency (ESA) and the Chinese Academy of Sciences (CAS). SMILE aims to study the solar wind-magnetosphere coupling in a novel approach: global imaging of the Earth’s magnetosheath and cusps in the soft X-ray band. At the same time, it also provides UV imaging of the northern auroral regions, completing the detection of solar wind–magnetosphere–ionosphere coupling in a global way. The time frame for launch is in 2025. This talk summarizes the recent progress of SMILE Modeling Working Group (MWG), specifically a special issue on Earth and Planetary Physics (EPP) with 23 articles to provide the international space science community with works regarding the modeling and data analysis methods developed during the pre-studies of the SMILE mission. We categorize the articles into the following topics and give some brief comments: (1) instrument descriptions of the Soft X-ray Imager (SXI), (2) modeling of the X-ray signals, (3) data processing of the images, (4) tracing the boundary locations from the simulated images, (5) physical phenomenon related to the scientific goals of SMILE-SXI, (6) modeling of the aurora, and (7) ground-based support for SMILE.

How to cite: Sun, T., Connor, H., and Samsonov, A.: The Special Issue on Modeling and Data Analysis Methods for the SMILE mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13469, https://doi.org/10.5194/egusphere-egu24-13469, 2024.

X3.27
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EGU24-1778
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ECS
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Studying the Earth's magnetopause at High Latitudes With CLUSTER 
Niklas Grimmich, Ferdinand Plaschke, C. Philippe Escoubet, Martin O. Archer, Rumi Nakamura, David G. Sibeck, and O. Dragos Constantinescu

The boundary between the interplanetary magnetic field and the terrestrial magnetic field is the magnetopause. This magnetopause is influenced by dynamic changes in the solar wind, i.e. different solar wind conditions lead to a change in the shape and location of the magnetopause. The interaction between the solar wind and the magnetosphere can be studied from in-situ spacecraft observations. Many studies focus on the equatorial plane, as this is where recent spacecraft constellations such as THEMIS or MMS operate. However, to fully capture the interaction, it is important to study the high latitude regions as well. The Cluster spacecraft allow us to collect a database of high-latitude magnetopause crossings and study magnetopause motion in this region, as well as deviations from established magnetopause models. We use multi-spacecraft analysis tools to investigate the direction of magnetopause motion in the high latitudes and compare the occurrence of crossings at different locations with the result in the equatorial plane. Our results will be useful for the interpretation of plasma measurements from the upcoming SMILE mission, as this spacecraft will also fly frequently through the high-latitude magnetopause.

How to cite: Grimmich, N., Plaschke, F., Escoubet, C. P., Archer, M. O., Nakamura, R., Sibeck, D. G., and Constantinescu, O. D.: Studying the Earth's magnetopause at High Latitudes With CLUSTER, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1778, https://doi.org/10.5194/egusphere-egu24-1778, 2024.

X3.28
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EGU24-8777
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ECS
A New Method of Estimating the Magnetopause Speed of Motion 
Mrittika Ghosh, Jana Šafránková, and Zdeněk Němeček

The magnetopause is the boundary where the solar wind and magnetosphere pressures balance each other. Once the upstream solar wind conditions change, the magnetopause moves to a new position and changes its shape accordingly. Previous studies usually calculate the speed of magnetopause motion from parameters of two crossings that were close in location and time. However, such events are relatively rare. A new hypothesis suggests application of the ion speed in the magnetopause layers to estimate the speed of magnetopause motion. As a boundary that plasma cannot pass through, the ion speed in the magnetopause should be related to the magnetopause speed. Our study aims to check whether this hypothesis is correct or not by using numerous magnetopause crossings recorded by the THEMIS mission. The magnetopause speed will be first calculated using the traditional method and compared with the results estimated using the new method.

How to cite: Ghosh, M., Šafránková, J., and Němeček, Z.: A New Method of Estimating the Magnetopause Speed of Motion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8777, https://doi.org/10.5194/egusphere-egu24-8777, 2024.

X3.29
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EGU24-2428
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ECS
Pc 4 Cavity mode wave frequency variation associated with inward motion of the magnetopause during interplanetary shock compression 
Dianjun Zhang, Wenlong Liu, Zhao Zhang, Xinlin Li, Theodore Sarris, Jerry Goldstein, and Rezvov Dmitry

A cavity mode wave, referring to a trapped or radially standing fast mode wave between different magnetospheric boundaries, has been developed in theory and reported in observation studies. In this study, we present an interplanetary shock (IPS)-induced cavity mode wave event observed outside the plasmasphere on 31 August 2017 with multispacecraft measurements. The phase delay of 90 degrees between the azimuthal electric field and compressional magnetic field indicates that the fast-mode wave triggered by the IPS is a standing wave, presumably radially trapped in the cavity between the magnetopause and plasmapause. Taking advantage of the location of VAP-B spacecraft right outside the plasmapause and the AARI ground-based high-latitude array mapped in the noon sector, it is suggested that the observed compressional wave associates to cavity mode with its inner boundary at the plasmapause and its outer boundary at the magnetopause. The peak frequency of the wavelet spectrum of the compressional magnetic field increases from 10.5 to 12.5 mHz, which is consistent with the theoretically calculated cavity eigenfrequencies before and after the IPS. We also provide the first evidence that the peak frequency of the cavity mode increases due to the inward motion of the magnetopause during IPS compression.

How to cite: Zhang, D., Liu, W., Zhang, Z., Li, X., Sarris, T., Goldstein, J., and Dmitry, R.: Pc 4 Cavity mode wave frequency variation associated with inward motion of the magnetopause during interplanetary shock compression, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2428, https://doi.org/10.5194/egusphere-egu24-2428, 2024.

X3.30
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EGU24-18081
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ECS
Signature of Alfvénic and compressive waves in corotating Solar Wind high-speed streams on low-frequency geomagnetic activity at high latitudes 
Giuseppina Carnevale, Mauro Regi, Patrizia Francia, Stefania Lepidi, and Domenico Di Mauro

In the Solar Wind (SW), when a fast stream overtakes a slower one, it forms a corotating high-speed stream (HSS) with an upstream corotating interaction region (CIR) and a downstream rarefaction region (RR). The SW speed and the interplanetary magnetic field (IMF) exhibit wide fluctuations within CIRs and HSSs, that may have effects on the geomagnetic activity. Our study aims to investigate the effects of Alfvénic and compressive low-frequency fluctuations within SW corotating streams at 1 AU on geomagnetic activity in the low-frequency range (Pc5, 1-7 mHz), as observed at high-latitude geomagnetic observatories in both hemispheres. We analyzed several corotating streams, which were analyzed together with the corresponding geomagnetic field data recorded at ground observatories at high latitudes. For each observatory, we estimated a long-term geomagnetic power background in correspondence with quiet geomagnetic activity periods (low Kp index); then, we re-scaled the power to the background to better highlight the geomagnetic variations during the selected events. For SW data, we rotated the IMF and SW velocity components at 1AU into the Mean ElectroMagnetic Field Aligned (MEMFA) reference frame to identify fluctuation along two main directions: one aligned and one orthogonal to the ambient magnetic field. We compared the re-scaled geomagnetic field power with SW parameters, such as the power of IMF and SW velocity along the two directions, as well as with two quadratic invariants used to describe MHD turbulence: the normalized cross-helicity and the normalized residual energy. This combined method helps distinguish between compressive and Alfvénic fluctuations, providing insights into their impact on low-frequency geomagnetic variations.

How to cite: Carnevale, G., Regi, M., Francia, P., Lepidi, S., and Di Mauro, D.: Signature of Alfvénic and compressive waves in corotating Solar Wind high-speed streams on low-frequency geomagnetic activity at high latitudes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18081, https://doi.org/10.5194/egusphere-egu24-18081, 2024.

X3.31
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EGU24-10841
Solar wind-driven Alfvénic energy flow in the dayside magnetosphere 
Andreas Keiling

There is ample evidence for significant Alfvénic activity in the dayside magnetosphere. One reported aspect has been the relationship between the IMF/solar wind parameters and the global Alfvénic Poynting flux in the coupled system. In this investigation, we add to the body of knowledge by presenting the dynamics of Alfvén waves as a global phenomenon as it occurs at the entry point to the dayside auroral acceleration region. In particular, we show how the global Alfven wave power and morphology evolves during geomagnetic storm developments, from storm sudden commencement to the end of storm recovery. To investigate this, we used data from the Polar satellite. By comparing our results with observations from low-altitude satellites, we demonstrate the dissipation of Alfvénic power in the dayside. During storms, the transfer of energy from the solar wind into geospace is largely increased, leading to enhanced energy transfer and deposition within the magnetosphere and ionosphere. Here, we are aiming to understand the wave aspect during storm evolution.

How to cite: Keiling, A.: Solar wind-driven Alfvénic energy flow in the dayside magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10841, https://doi.org/10.5194/egusphere-egu24-10841, 2024.

X3.32
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EGU24-16135
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ECS
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Highlight
Vlasiator in 6D: magnetosphere-ionosphere coupling upgrades and automatic global flux rope identification 
Yann Pfau-Kempf and the Vlasiator team

We present recent and upcoming upgrades to the coupled ionosphere model now included in the global hybrid-Vlasov magnetospheric simulation Vlasiator. The handling of the magnetic field at the boundary has been corrected. The model used to obtain the parameterized precipitating electron fluxes is being upgraded to a more modern and flexible approach, and that new model is applied to obtain the precipitating proton fluxes from their velocity distribution function at the coupling radius in the hybrid-Vlasov domain.

Benefiting from the development of efficient runtime tracing of the magnetic field at the highest resolution, magnetic connectivity information is available at every point in the simulation, at every step. This information allows fast identification of the major domains of the near-Earth environment. Using magnetic field connectivity information we also introduce a novel approach to automatically and comprehensively detect magnetic flux rope structures of any scale and spatial orientation in the whole simulation domain.

How to cite: Pfau-Kempf, Y. and the Vlasiator team: Vlasiator in 6D: magnetosphere-ionosphere coupling upgrades and automatic global flux rope identification, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16135, https://doi.org/10.5194/egusphere-egu24-16135, 2024.

X3.33
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EGU24-13633
Observations of solar wind-magnetosphere-ionosphere coupling and its impact on equatorial ionospheric electrodynamics during the March and April 2023 geomagnetic storms 
Guan Le, Guiping Liu, and Endawoke Yizengaw

The low-latitude ionosphere is effectively shielded from the high latitude convection electric field during geomagnetic quiet times because region-2 field-aligned currents associated with the partial ring current act to oppose the convection electric field associated with region-1 field-aligned currents. However, the low-latitude ionosphere can be directly coupled to the enhanced magnetospheric electric field through prompt penetration of convection electric field during periods of strong solar wind-magnetosphere interaction. The mechanisms that lead to the generation of prompt penetration electric field during enhanced solar wind-magnetosphere-ionosphere coupling are complex and not fully understood. We study the evolution of field-aligned currents and the equatorial electrojet during the March and April 2023 geomagnetic storm to understand the processes involving solar wind disturbances interacting with the magnetosphere and coupling into the polar ionosphere, and how the low-latitude ionosphere responded to the enhanced magnetosphere-ionosphere coupling. We will present the observations in the solar wind-magnetosphere-ionosphere system, in particular, field-aligned currents at high latitude ionosphere by Swarm and the equatorial electrojet by Swarm and ground-based magnetometers.

 

How to cite: Le, G., Liu, G., and Yizengaw, E.: Observations of solar wind-magnetosphere-ionosphere coupling and its impact on equatorial ionospheric electrodynamics during the March and April 2023 geomagnetic storms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13633, https://doi.org/10.5194/egusphere-egu24-13633, 2024.

X3.34
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EGU24-5892
A Statistical and Multiscale study of Kelvin-Helmholtz events under different IMF orientations  
Adriana Settino, Rumi Nakamura, Yuri Khotyaintsev, Daniel B. Graham, Kevin-Alexander Blasl, Takuma Nakamura, and Denise Perrone

The Kelvin-Helmholtz instability (KHI) is a shear-driven phenomenon frequently observed at the Earth's low-latitude magnetopause when the velocity shear is super Alfvénic. KHI represents a way for plasmas to give rise to a turbulent scenario and to convert the energy due to the large-scale motion of the shear flow into heat. Indeed, the evolution of the KHI is characterized by the nonlinear coupling of different modes, which tends to generate smaller and smaller vortices along the shear layer. Both kinetic simulations and in situ measurements, focusing on the kinetic effects during the nonlinear phase of the instability, have shown the generation of strong current sheets between well-developed vortices, and temperature anisotropy and agyrotropy at both ion and electron scales, in accordance with the multi-scale nature of the phenomenon.

Moreover, KHI is thought to play a crucial role in the transport of solar wind plasma into the magnetosphere and to efficiently contribute to the formation of the low latitude boundary layer. Although the instability threshold is equally satisfied during both northward and southward interplanetary magnetic field (IMF) conditions, in-situ measurements show that KHI privileges the northward orientation. We investigate this different behavior by analyzing the kinetic features at both boundaries and inside the KH structures. Thus, we statistically investigate several KHI crossings observed by the Magnetospheric Multiscale mission for different IMF orientations. Our statistical study can provide a better understanding about the global dynamics of the near Earth's environment and gives an important contribution to the solar wind-magnetosphere coupling mechanism.

How to cite: Settino, A., Nakamura, R., Khotyaintsev, Y., Graham, D. B., Blasl, K.-A., Nakamura, T., and Perrone, D.: A Statistical and Multiscale study of Kelvin-Helmholtz events under different IMF orientations , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5892, https://doi.org/10.5194/egusphere-egu24-5892, 2024.

X3.35
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EGU24-1968
Reproducing the magnetospheric response to southward turnings in MHD simulations 
Andrey Samsonov, Stephen Milan, Tianran Sun, Natalia Buzulukova, Jacobo Varela, and Colin Forsyth

State-of-the-art numerical models have been developed to reproduce magnetospheric dynamics in response to solar wind variations. However, we do not understand how accurate the predictions of the models would be in different solar wind and magnetospheric conditions. In this study, we consider the two relatively simple cases with southward interplanetary magnetic field turnings which have been simulated by several MHD models (SWMF, LFM, PPMLR-MHD, PLUTO). We compare numerical results with observations in terms of global magnetospheric characteristics such as the polar cap open flux and the indices of magnetospheric activity. Our purpose is to understand why some models can make better predictions. To answer this question we also compare the results of the same MHD model with different numerical resolutions and ionospheric conductances and show that both resolution and conductance are important for accurate predictions. By comparing simulations with observations, we can figure out the optimal parameters in the models which should be used in the future.

How to cite: Samsonov, A., Milan, S., Sun, T., Buzulukova, N., Varela, J., and Forsyth, C.: Reproducing the magnetospheric response to southward turnings in MHD simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1968, https://doi.org/10.5194/egusphere-egu24-1968, 2024.

X3.36
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EGU24-11173
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ECS
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Highlight
Unusual shrinkage and reshaping of Earth’s magnetosphere under a strong northward interplanetary magnetic field 
Xiangyu Wang, Qinghe Zhang, Chi Wang, Yongliang Zhang, Binbin Tang, Zanyang Xing, Kjellmar Oksavik, Larry R. Lyons, Michael Lockwood, Qiugang Zong, Guojun Li, Jing Liu, Yuzhang Ma, and Yong Wang

Open magnetic flux in the polar cap almost completely disappeared and the Earth's magnetotail was compressed into a calabash shape during the 9th April 2015 coronal mass ejection, according to magnetohydrodynamic simulations and observations from DMSP and THEMIS.The Earth's magnetosphere is the region of space where plasma behavior is dominated by the geomagnetic field. It has a long tail typically extending hundreds of Earth radii (R-E) with plentiful open magnetic fluxes threading the magnetopause associated with magnetic reconnection and momentum transfer from the solar wind. The open-flux is greatly reduced when the interplanetary magnetic field points northward, but the extent of the magnetotail remains unknown. Here we report direct observations of an almost complete disappearance of the open-flux polar cap characterized by merging poleward edges of a conjugate horse-collar aurora (HCA) in both hemispheres' polar ionosphere. The conjugate HCA is generated by particle precipitation due to Kelvin-Helmholtz instability in the dawn and dusk cold dense plasma sheets (CDPS). These CDPS are consist of solar wind plasma captured by a continuous dual-lobe magnetic reconnections, which is further squeezed into the central magnetotail, resulting in a short "calabash-shaped" magnetotail.

How to cite: Wang, X., Zhang, Q., Wang, C., Zhang, Y., Tang, B., Xing, Z., Oksavik, K., Lyons, L. R., Lockwood, M., Zong, Q., Li, G., Liu, J., Ma, Y., and Wang, Y.: Unusual shrinkage and reshaping of Earth’s magnetosphere under a strong northward interplanetary magnetic field, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11173, https://doi.org/10.5194/egusphere-egu24-11173, 2024.

X3.37
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EGU24-5292
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ECS
A Statistical Study of the Properties of and Geomagnetic Responses to Large, Rapid Southward Turnings of the Interplanetary Magnetic Field 
Chiara Lazzeri, Colin Forsyth, Andrei Samsonov, Graziella Branduardi-Raymont, and Yulia Bogdanova

The interplanetary magnetic field (IMF) north-south component, Bz, plays a crucial role in the interaction between the solar wind and the Earth's magnetosphere. We analyse 98 intervals in which Bz changed from > 3 nT to < -3 nT in 5 min and for which these rapid southward turnings (STs) were surrounded by consistently northward or southward IMF.
This analysis is performed separately for events in proximity of interplanetary coronal mass ejections (ICMEs) and corotating interaction regions (CIRs). We find that IMF magnitude, solar wind dynamic pressure and proton density (but also flow speed and plasma pressure in ICME-associated events) are enhanced above their median values. We analyse the maximum responses of the SML, SMU, SYM-H and PC magnetospheric indices and their timescales, but also the occurrence of geomagnetic phenomena. We find that magnetic storms followed 46.94% of events, with the strongest storms (with median SYM-H -120 nT) following ICME turnings. STs were followed by either substorms (60.20%) or enhanced convection (37.76%). While SML has similar average minima (~ -460 nT) and timescales (~ 56 min) for substorm and convection events, SMU has noticeable differences. PCN is found to have peaks (3.8 mV/m) around 30 minutes after the turning, and larger ones (4.9 mV/m) later. Stronger solar wind driving and magnetospheric responses are observed in ICME turnings. 
Examining the correlation between the geomagnetic and solar wind parameters around STs, reveals a more direct link between solar wind driving and geomagnetic response for STs than at other times.

How to cite: Lazzeri, C., Forsyth, C., Samsonov, A., Branduardi-Raymont, G., and Bogdanova, Y.: A Statistical Study of the Properties of and Geomagnetic Responses to Large, Rapid Southward Turnings of the Interplanetary Magnetic Field, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5292, https://doi.org/10.5194/egusphere-egu24-5292, 2024.

X3.38
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EGU24-15889
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Highlight
Wave storms in the Earth's magnetosphere
(withdrawn)
Lucile Turc, Mirja Ojuva, Sanni Hoilijoki, Adnane Osmane, and Emilia Kilpua
X3.39
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EGU24-13267
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Highlight
Analysis of Cluster data with the publicly available GRMB (Geospace Region and Magnetospheric Boundary) dataset 
Benjamin Grison, Fabien Darrouzet, Romain Maggiolo, Mykhaylo Hayosh, and Matthew Taylor

The Cluster mission consists of 4 identical spacecraft, each carrying 11 scientific experiments. The spacecraft were launched in July and August 2000 into near polar inclined, 19x4 RE elliptic orbits. All four spacecraft are still in operation 23 years later. The magnetosphere environment is highly dynamic and its regions cannot be accessed by the orbital information alone. The purpose of this study is to develop a comprehensive dataset, providing information on Geospace Region and Magnetospheric Boundaries (GRMB) crossed by each of the four Cluster spacecraft, and to deliver it to the Cluster Science Archive (CSA).

The GRMB dataset provides a classification useful for the scientific community. Therefore, the methodology does not define what is a bow shock or what is a magnetopause. The goal is to have labeled regions that contain the bow-shocks or magnetopauses. And then each user can apply its own definition on the appropriate label subset.

The GRMB list contains two kinds of items:

  • Regions: Magnetosphere, Magnetosheath, Lobe, Solar wind / Foreshock, Plasmasheet, Plasmasphere

  • Transition regions: Bow shock TR, Magnetopause TR, Polar regions, Plasmasheet TR, Plasmapause TR

Transition regions can include properties matching several regions. For example, a bow shock TR can include short periods of solar wind or magnetosheath. Solar wind and magnetosheath should not include bow shock crossings.

The GRMB dataset is based on more than 40 data products available at CSA, taken from 7 instrument suites. The methodology relies on the visual identification of the boundaries between two consecutive GRMB items.

The methodology, the criteria applied for the boundary identification, and the dataset validation are presented. The dataset is not yet fully completed but the Cluster location is already available for more than 5 years per spacecraft.

The visualization of the regions, and their physical properties, crossed by the Cluster spacecraft during several years, illustrates the scientific interest of this dataset.

How to cite: Grison, B., Darrouzet, F., Maggiolo, R., Hayosh, M., and Taylor, M.: Analysis of Cluster data with the publicly available GRMB (Geospace Region and Magnetospheric Boundary) dataset, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13267, https://doi.org/10.5194/egusphere-egu24-13267, 2024.

X3.40
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EGU24-17645
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Highlight
Unveiling plasma energization and energy transport in the Earth’s Magnetospheric System through multi-scale observations: the science of the Plasma Observatory mission 
Alessandro Retinò and Maria Federica Marcucci and the Plasma Observatory Team

Energetic plasma is everywhere in the Universe. We observe plasma energization and energy transport in a variety of cosmic plasmas, such as planetary magnetospheres, stellar coronae, supernova remnant shocks, accretion disks, and astrophysical jets. The Earth’s Magnetospheric System is a key example of a complex and highly dynamic cosmic plasma environment where massive energy transport and plasma energization occur and can be directly studied through in situ spacecraft measurements. Despite the large amount of available in situ observations, however, we still do not fully understand how plasma energization and energy transport work. This is essential for understanding how our planet works, including space weather science, and is also important for the comprehension of distant astrophysical plasma environments. In situ observations, theory and simulations suggest that the key physical processes driving energization and energy transport occur where plasma on fluid scales couple to the smaller ion kinetic scales, at which the largest amount of electromagnetic energy is converted into energized particles. Remote observations currently cannot access these scales, and existing multi-point in situ observations do not have a sufficient number of observation points. Plasma Observatory will be the first mission having the capability to resolve scale coupling in the Earth’s Magnetospheric System through measurements of fields and particles at seven points in space, covering simultaneously ion and fluid scales in the Key Science Regions where the strongest plasma energization and energy transport occurs: the foreshock, bow shock, magnetosheath, magnetopause, magnetotail current sheet, and transition region. By resolving scale coupling in fundamental plasma processes such as shocks, magnetic reconnection, waves and turbulent fluctuations, plasma jets, field-aligned currents and plasma instabilities, these measurements will allow us to answer the two Plasma Observatory science questions (Q1) How are particles energized in space plasmas ? and (Q2) Which processes dominate energy transport and drive coupling between the different regions of the Earth’s Magnetospheric System? Plasma Observatory will also address important additional science targets such effects of ionospheric processes on the Magnetospheric System (e.g. ion outflows), outer radiation belts processes, solar wind physics and space weather science, which will increase  the scientific return of the PO mission. Going beyond the limitations of current ESA/Cluster and NASA/MMS four-point constellations, which can only resolve plasma processes at individual scales, Plasma Observatory will  transform our understanding of the plasma environment of our planet with a major impact on the understanding of astrophysical plasmas too.

How to cite: Retinò, A. and Marcucci, M. F. and the Plasma Observatory Team: Unveiling plasma energization and energy transport in the Earth’s Magnetospheric System through multi-scale observations: the science of the Plasma Observatory mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17645, https://doi.org/10.5194/egusphere-egu24-17645, 2024.

X3.41
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EGU24-8122
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ECS
Capabilities of the wave telescope for multi-scale spacecraft configurations using a Vlasiator simulation 
Leonard Schulz, Ferdinand Plaschke, Karl-Heinz Glassmeier, Uwe Motschmann, Yasuhito Narita, Minna Palmroth, Owen Roberts, and Lucile Turc

We present an analysis of the wave properties in Earth's foreshock and dayside magnetosphere in a Vlasiator global magnetospheric simulation, using the wave telescope analysis technique. Vlasiator is a Hybrid-Vlasov plasma simulation and treats electrons as a fluid while protons are described by distribution functions. In anticipation of future multi-scale spacecraft space plasma missions such as HelioSwarm or the proposed Plasma Observatory, artificial spacecraft constellations consisting of more than 4 satellites have been used to measure the electromagnetic field and plasma properties in the Vlasiator run. Using the wave telescope analysis technique - originally developed for the 4-spacecraft Cluster mission - power spectra in k-space are estimated, enabling the determination of properties of waves and transient phenomena from those multi-scale spacecraft data. We test different spacecraft configurations probing regions mainly in the foreshock and consider conversion to the plasma rest frame, dispersion analysis as well as spectrum filtering to account for the spatial Nyquist limit in k-space spectra.

How to cite: Schulz, L., Plaschke, F., Glassmeier, K.-H., Motschmann, U., Narita, Y., Palmroth, M., Roberts, O., and Turc, L.: Capabilities of the wave telescope for multi-scale spacecraft configurations using a Vlasiator simulation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8122, https://doi.org/10.5194/egusphere-egu24-8122, 2024.

X3.42
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EGU24-15083
Constellation of N Spacecraft : the Aliasing Problem 
Gérard M. Chanteur

Constellations of N spacecraft allow to separate spatial and temporal variations of the electromagnetic field in space as demonstrated by achievements of CLUSTER and MMS missions. Future missions in preparation, involving more than four spacecraft, will offer new opportunities beside proper technological progress in sensors and electronic design : the genuine and promising aspect is the number of spacecraft larger than four. Four spacecraft is the minimal configuration to estimate gradients and to do spatial filtering in three dimensions. More than four spacecraft gives additional degrees of freedom by weighting the constellation ; a numerical weight is attributed to each spacecraft for computing gradients or doing spatial filtering. It has been early recognized that spatial filtering by a constellation of spacecraft is limited by spatial aliasing ; theoretical considerations, for example dispersion relations, allow to discriminate aliased energy peaks. Discriminating aliased energy peaks with more than four space spacecraft is possible just by changing the weighting of the constellation as will be shown for the simplest case N=5. First the aliasing equation is reminded, then the fundamental cell is defined and visualized, and it is shown that aliased peaks are moving when changing the weighting. Meanwhile non-aliased peaks are unaffected.

How to cite: Chanteur, G. M.: Constellation of N Spacecraft : the Aliasing Problem, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15083, https://doi.org/10.5194/egusphere-egu24-15083, 2024.

X3.43
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EGU24-4965
The wedge-like ion spectral structures in the inner magnetosphere 
Jie Ren, Qiugang Zong, Xuzhi Zhou, and Chao Yue

Energetic ions from the plasma sheet will be freshly injected into the inner magnetosphere during geomagnetic activities, and exhibit some spectral features named after the shapes of energy bands in the energy-time spectrograms such as the “nose-like” structure,“trunk-like” structure, and ion spectral gap. Using the ion observations from Van Allen Probes launched in 2012, my work revealed the existence of a new ion structures, which is the wedge-like structure of O+, He+, and H+ ions in the inner magnetosphere. The wedge-like structures have the energy range of eV-keV and can penetrate into deep regions (even L<2). Via the conjugate observations of different spacecraft and simulations, we found that the wedge-like and nose-like spectral signatures are merely the manifestations of one single structure along different spacecraft trajectories, which are associated with the intermittent substorm injections in the nightside magnetosphere. The comparisons between observations and simulations of the wedge-like structures can help find out the shortcomings of the empirical convection electric models and improve them.

How to cite: Ren, J., Zong, Q., Zhou, X., and Yue, C.: The wedge-like ion spectral structures in the inner magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4965, https://doi.org/10.5194/egusphere-egu24-4965, 2024.

X3.44
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EGU24-3490
Multi-case study of particle distribution functions associated with ion cyclotron waves at ballooning-interchange heads 
Evgeny V. Panov, Wolfgang Baumjohann, Martin Hosner, Rumi Nakamura, and Victor A. Sergeev

Recent THEMIS and MMS spacecraft observations confirmed the kinetic simulations showing that the kinetic Ballooning/Interchange Instability (BICI) may lead to off-equator electromagnetic ion-cyclotron waves.  The ion-cyclotron waves appeared to ripple the growing ballooning-interchange heads and to erode and thin the magnetotail current sheet at ion scales. As this wave activity may be important for initiating magnetic reconnection in the magnetotail, we aim at collecting a number of high-resolution MMS ion observations with clear signatures of the electromagnetic ion-cyclotron waves, and at investigating the particle behavior caused by the waves. Particularly, we analyze the properties of the electromagnetic ion cyclotron waves and search for signatures of wave interaction with resonant particles using partial ion distribution functions and their moments.

How to cite: Panov, E. V., Baumjohann, W., Hosner, M., Nakamura, R., and Sergeev, V. A.: Multi-case study of particle distribution functions associated with ion cyclotron waves at ballooning-interchange heads, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3490, https://doi.org/10.5194/egusphere-egu24-3490, 2024.

X3.45
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EGU24-6258
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ECS
Statistical Survey of Ion Cyclotron Wave Signatures around Earth’s Magnetotail Dipolarizations 
Martin Hosner, Rumi Nakamura, Evgeny Panov, and Daniel Schmid

In the Earth’s Magnetotail fast earthward plasma flows (so-called Bursty Bulk Flows) with a duration of several minutes and velocities of several hundreds of km/s are regularly observed in in-situ measurements. These flows are frequently accompanied by embedded co-moving, and more dipolar-shaped, magnetic flux bundles. The leading edge of such flux bundles is called a Dipolarization Front (DF). Such Earthward moving flux bundles and DFs can be formed by magnetic reconnection in the Magnetotail, as well as by the Ballooning/Interchange Instability (BICI). For the latter mechanism, simulations of the BICI suggest that, away from the central plasma sheet, the BICI heads are accompanied by electromagnetic ion cyclotron waves, and such wave signatures were indeed observed by the MMS and THEMIS spacecraft between the neutral sheet and the magnetospheric lobes.

In the present study we use years of data from NASA’s Magnetospheric Multiscale Mission (MMS) to compile a database of several hundred events. We analyze this database with the goal of a statistical description of such flux bundles with respect to ion cyclotron wave occurrence, and compare them to several parameters, such as magnetic field and plasma conditions, to further enhance the understanding of the large-scale context and origin of magnetotail dipolarizations.

How to cite: Hosner, M., Nakamura, R., Panov, E., and Schmid, D.: Statistical Survey of Ion Cyclotron Wave Signatures around Earth’s Magnetotail Dipolarizations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6258, https://doi.org/10.5194/egusphere-egu24-6258, 2024.

X3.46
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EGU24-8525
Observations of Electron Secondary Reconnection in Magnetic Reconnection Front 
Liu Chengming

Magnetic reconnectio­n, a fundamental plasma process transforming magnetic field energy into particle energy, is ubiquitous in space and responsible for many explosive phenomena, such as solar flares and gamma ray bursts. Recent numerical theories have predicted that reconnection fronts far from the primary reconnection region can host secondary reconnection in three-dimensional scenarios, different from the conventional two-dimensional diagram where only one X-line stands to sustain reconnection. In this study, we provide direct observational evidence for ongoing secondary reconnection in the reconnection front, via using the unprecedently high-cadence data from NASA’s MMS mission. The secondary reconnection is identified by the presence of X-line, super-Alfvénic electron jet, and non-ideal energy dissipation. Different from the primary ion-electron reconnection, the secondary reconnection is electron-only, with its X-line quasi-perpendicular to the primary X-line. Hence reconnection, when evolving from local to global scales, becomes essentially three-dimensional with different patterns developed. These results provide crucial insights into understanding cross-scale energy transport driven by reconnection in space plasmas.

How to cite: Chengming, L.: Observations of Electron Secondary Reconnection in Magnetic Reconnection Front, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8525, https://doi.org/10.5194/egusphere-egu24-8525, 2024.

X3.47
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EGU24-16113
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ECS
Finding reconnection lines and flux rope axes via local coordinates in global ion-kinetic magnetospheric simulations 
Markku Alho, Giulia Cozzani, Ivan Zaitsev, Fasil Tesema Kebede, Urs Ganse, Markus Battarbee, Maarja Bussov, Maxime Dubart, Sanni Hoilijoki, Leo Kotipalo, Konstantinos Papadakis, Yann Pfau-Kempf, Jonas Suni, Vertti Tarvus, Abiyot Workayehu, Hongyang Zhou, and Minna Palmroth

Magnetic reconnection is a crucially important process for energy transfer in plasma physics, the substorm cycle of Earth's magnetosphere and solar flares being prime examples. While 2D models have been widely applied to study reconnection, investigating reconnection in 3D is still in many aspects an open problem. Finding sites of magnetic reconnection in a 3D setting is not a trivial task, with several approaches from topological skeletons to Lorentz transformations proposed to tackle the issue. This work presents a complementary method by noting that the magnetic field structures near reconnection lines exhibit two-dimensional features that can be identified in a suitably chosen local coordinate system. We present applications of this method, with two approaches, to a hybrid-Vlasov Vlasiator simulation of the Earth's magnetosphere, showing the complex magnetic topologies created by reconnection. We also overview the dimensionalities of magnetic field structures in the simulation to support the use of such coordinate systems.

How to cite: Alho, M., Cozzani, G., Zaitsev, I., Kebede, F. T., Ganse, U., Battarbee, M., Bussov, M., Dubart, M., Hoilijoki, S., Kotipalo, L., Papadakis, K., Pfau-Kempf, Y., Suni, J., Tarvus, V., Workayehu, A., Zhou, H., and Palmroth, M.: Finding reconnection lines and flux rope axes via local coordinates in global ion-kinetic magnetospheric simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16113, https://doi.org/10.5194/egusphere-egu24-16113, 2024.

X3.48
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EGU24-84
Contribution of patchy reconnection to the ion to electron temperature ratio in the Earth’s magnetotail
(withdrawn)
Chuxin Chen and Chih-Ping Wang
X3.49
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EGU24-9641
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ECS
Energy conversion in a compressed magnetospheric separatrix: Observations and simulations 
Mohammed Baraka, Olivier Le Contel, Patrick Canu, Soboh Alqeeq, Mojtaba Akhavan-Tafti, Alessandro Retino, Thomas Chust, Sergio Toledo-Redondo, Jeremy Dargent, Arnaud Beck, Giulia Cozzani, and Cecilia Norgren and the MMS Team

Magnetic reconnection is a fundamental process that is ubiquitous in the universe. It converts magnetic field energy into heating and acceleration of plasma. On the dayside of the Earth’s magnetosphere, it is responsible for the dominant transport of plasma, momentum, and energy across the magnetopause from the solar wind into the Earth’s magnetosphere. The present study reports on a magnetic reconnection event with a guide field (BM=0.5 B) detected by the Magnetospheric Multiscale mission (MMS) on October 21, 2015, around 04:39:24 UT. The MMS traversed the compressed magnetospheric separatrix and the reconnection jet far from the diffusion regions and in specific conditions: observing magnetospheric cold ions and a large magnetosheath density of up to 150 p/cc. We investigate the generalized Ohm’s law and the energy conversion process in the spacecraft frame (J.E) and in the fluid frame (J.E`) associated with the separatrix crossing under such conditions. We further validate and compare our results using 2D fully kinetic simulation.

How to cite: Baraka, M., Le Contel, O., Canu, P., Alqeeq, S., Akhavan-Tafti, M., Retino, A., Chust, T., Toledo-Redondo, S., Dargent, J., Beck, A., Cozzani, G., and Norgren, C. and the MMS Team: Energy conversion in a compressed magnetospheric separatrix: Observations and simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9641, https://doi.org/10.5194/egusphere-egu24-9641, 2024.

X3.50
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EGU24-5222
Observational investigation of Hall effect in asymmetric magnetic reconnection  
Yongcun Zhang

Using MMS observation, we do a series of studies to investigate Hall effect in multiple reconnection cases at dayside magnetopause. The studies show the following interesting results. First, the hexapolar Hall magnetic field was observed in collisionless magnetic reconnection for the first time. And the associated electric field and electron dynamic display the different features from previous study. Second, it was found that the middle polar of hexapolar Hall magnetic field can play the role of guide field. Thus, hexapolar Hall magnetic field can make antiparallel reconnection to bear the features of guide field reconnection. Furthermore, the coexistence of hexapolar Hall magnetic field and magnetic flux rope provides the first evidence that the Hall effect in quasi-antiparallel magnetic reconnection can generate the core field inside a magnetic flux rope. Finally, for three reconnection events at the magnetopause, the quadrupolar Hall magnetic fields in them display their respective properties on the intensity asymmetry and the distributing location. The analyses indicate that the different density asymmetry inside the Hall region, but not the asymptotic density asymmetry, is an exact indicator that explains the different observed Hall patterns. This series of studies offer a new insight into the role of Hall effect in collisionless magnetic reconnection, and how the Hall effect works with the evolution of asymmetry during reconnection. 

How to cite: Zhang, Y.: Observational investigation of Hall effect in asymmetric magnetic reconnection , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5222, https://doi.org/10.5194/egusphere-egu24-5222, 2024.

X3.51
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EGU24-13917
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ECS
Hall Nature Ahead of Dipolarization Fronts in the Earth's Magnetotail 
Lei Wang and Can Huang

Dipolarization front (DF), a common magnetic structure at the leading edge of fast plasma jets in the Earth's magnetotail, plays an important role in magnetic energy release and may even modify the magnetotail energy budgets. To date, the physical process within the structure has been well studied. However, the effect of the structure on the background plasma sheet remains elusive. Using recent high-quality data from the Magnetospheric Multiscale (MMS) mission, we statistically investigate this issue. Ahead of the DF, we find a bipolar By structure, which is consistent with the local Hall current system. The main carriers of the current system are also studied. Our research advances the understanding of the interaction between the DF and ambient undisturbed plasma environment.

How to cite: Wang, L. and Huang, C.: Hall Nature Ahead of Dipolarization Fronts in the Earth's Magnetotail, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13917, https://doi.org/10.5194/egusphere-egu24-13917, 2024.