ST2.7

EDI
Global magnetospheric dynamics in simulations and observations

Large-scale dynamic processes in different magnetospheric regions, e.g., at the magnetopause, in the dayside magnetosphere, magnetotail, ring current, plasmasphere, ionosphere, are generally interconnected therefore the magnetosphere should be considered as a global system. The state of the magnetosphere is controlled mainly by solar wind conditions. The interplanetary magnetic field (IMF) and solar wind plasma parameters regulate the energy input into the magnetosphere. Magnetic reconnection at the dayside magnetopause and in the tail current layer regulate energy transfer through the magnetosphere. Changes in the solar wind dynamic pressure and IMF move the magnetopause, causing global magnetospheric expansions and contractions. Variations in the solar wind velocity and IMF direction may also displace the magnetotail. Processes within the magnetotail inject thermal and energetic particles into the inner magnetosphere and downward along magnetic field lines into the ionosphere. On the other hand, the polar wind from the upper atmosphere may influence nightside reconnection rates. Global magnetospheric dynamics can be studied by means of numerical simulations (MHD or kinetic), using empirical and semi-empirical models, or with the help of multipoint in situ spacecraft observations. Arrays of ground-based observatories and individual well-situated 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. Accurate modelling of global magnetospheric processes is an essential condition for successful space weather predictions. We welcome any work presenting results on the global dynamics of the Earth’s magnetosphere as well the magnetospheres of other planets and for instance modeling activities undertaken for the preparation of the future Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) mission.

Convener: Andrey Samsonov | Co-conveners: Yulia Bogdanova, C.-Philippe Escoubet, David Sibeck
Presentations
| Thu, 26 May, 15:10–18:27 (CEST)
 
Room L1, Fri, 27 May, 08:30–09:05 (CEST)
 
Room L1

Session assets

Session materials

Presentations: Thu, 26 May | Room L1

Chairpersons: Andrey Samsonov, Zdenek Němeček, Yulia Bogdanova
15:10–15:15
15:15–15:22
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EGU22-801
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Highlight
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Presentation form not yet defined
C.-Philippe Escoubet, Chi Wang, and Graziella Branduardi-Raymont and the SMILE team

The interaction between the solar wind and the Earth's magnetosphere, and the geospace dynamics that result, is one of the key questions in space plasma physics. In situ instruments on a fleet of solar wind and magnetospheric constellation missions now provide the most detailed observations of Sun-Earth connections over multiple scales, from the smallest of a few kilometres up to the largest of a few 10s of Earth radii. However, we are still unable to quantify the global effects of the drivers of such connections, including the conditions that prevail throughout geospace. This information is the key missing link for developing a complete understanding of how the Sun gives rise to and controls Earth's plasma environment and space weather. This is where SMILE (Solar wind Magnetosphere Ionosphere Link Explorer) comes in.
SMILE is a novel self-standing mission dedicated to observing the solar wind - magnetosphere coupling via simultaneous in situ solar wind/magnetosheath plasma and magnetic field measurements, soft X-ray imaging of the magnetosheath, magnetopause and polar cusps, and UV imaging of the Northern hemisphere auroral oval. Remote sensing of the magnetosheath and cusps with soft X-ray imaging is made possible thanks to solar wind charge exchange (SWCX) X-ray emissions known to occur in the vicinity of the Earth's magnetosphere. SMILE is a joint mission between ESA and the Chinese Academy of Sciences (CAS) due for launch at the end of 2024. SMILE science objectives as well as the latest technical developments jointly undertaken by ESA and CAS and the international instrument teams will be presented.

How to cite: Escoubet, C.-P., Wang, C., and Branduardi-Raymont, G. and the SMILE team: Imaging the magnetosphere with the SMILE Mission, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-801, https://doi.org/10.5194/egusphere-egu22-801, 2022.

15:22–15:29
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EGU22-5654
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ECS
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Highlight
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On-site presentation
Bayane Michotte de Welle, Nicolas Aunai, Gautier Nguyen, Benoit Lavraud, Vincent Genot, Roch Smets, and Alexis Jeandet

Understanding where the magnetic reconnection occurs at the Earth’s magnetopause is one of the important remaining questions about this phenomena. Since the last decades various models predicting the position of the X-line have been made. These models largely depend on the orientation of the magnetic field in the magnetosheath close to the magnetopause, such as the Maximum Magnetic Shear model (Trattner et al 2007). Therefore understanding how it  is structured as a function of the solar wind and interplanetary magnetic field is of pivotal importance. Machine learning was used to collect around 45 million measurements in the magnetosheath at 5s resolution in all available Cluster, MMS, Double Star, THEMIS dataset, and to build detailed maps of the field structure in that region as a function of the IMF orientation. It allowed us to reconstruct for the first time the three dimensional magnetic field draping in the dayside magnetosheath from in-situ data only. Our results reveal how the frozen-in condition constrains the draping around the magnetopause. A comparison of the draping obtained with in-situ data with the one from a widely used magnetostatic model (Kobel et al 1994) was made. Differences of up to 180° were found for cone angle between 12.5° and 45°, for which the consequences regarding the position of the X-line will be discussed. 

 

How to cite: Michotte de Welle, B., Aunai, N., Nguyen, G., Lavraud, B., Genot, V., Smets, R., and Jeandet, A.: Global three-dimensional draping of magnetic field in Earth's magnetosheath from in-situ measurements, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5654, https://doi.org/10.5194/egusphere-egu22-5654, 2022.

15:29–15:36
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EGU22-7248
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On-site presentation
Ferdinand Plaschke, Florian Koller, Luis Federico Preisser Renteria, Adrian T. LaMoury, Heli Hietala, Manuela Temmer, and Owen Wyn Roberts

Plasma jets in the magnetosheath are identified as strong local enhancements in dynamic pressure. Being created at the bow shock, they are able to traverse the entire magnetosheath and impact the magnetopause. There, they can severely indent the boundary, set up waves on it, and trigger magnetic reconnection. They are a key yet heavily underexplored element in the solar wind – magnetosphere coupling. Jets are mostly (but not exclusively) observed downstream of the quasi-parallel shock. Consequently, they have been observed significantly more often under low interplanetary magnetic field cone angle conditions.

In this study, we revisit the occurrence of jets, this time taking into account the whole space of parameters of solar wind input conditions. We answer the question where in this space jet occurrences cluster and how the emerging patterns change when the solar wind input becomes significantly different in nature, e.g., under the influence of coronal mass ejections or stream interaction regions.

How to cite: Plaschke, F., Koller, F., Preisser Renteria, L. F., LaMoury, A. T., Hietala, H., Temmer, M., and Roberts, O. W.: Magnetosheath jet occurrence in solar wind parameter space, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7248, https://doi.org/10.5194/egusphere-egu22-7248, 2022.

15:36–15:43
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EGU22-11573
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On-site presentation
Marius Echim, Mirela Voiculescu, Costel Munteanu, Gabriel Voitcu, Eliza Teodorescu, Simona Condurache-Bota, Emilian Bujor Dănilă, and Cătălin Negrea

We analize magnetosheath Cluster data from 2007 and 2008, included in FP7 STORM database (http://www.storm-fp7.eu). We identify magnetosheath jets based on a procedure that searches for significant departures of the local dynamic pressure from an average value.  The latter  is estimated from a running window spanning 20 minutes of data. The selection criterion is applied on Cluster 3 dataset and identifies 955 magnetosheath jets, with a notable difference between 2007 and 2008 (352 versus 603 events). The statistical analysis of the plasma bulk velocity, density, temperature, plasma beta, magnetic field and radial distance of the jets provides interesting elements for understanding their dynamics. There is evidence for deceleration of jets with decreasing distance from the Earth; interestingly, this trend manifests more clearly for jets detected in 2008. More jets are found in the dawn than in the dusk flank, for 2007 and 2008.  A comparison with the plasma parameters of the driver, the IMF Bz and the solar wind dynamic pressure from OMNI database, indicate there is no preference in terms of Bz polarity. The distribution of jet magnetic field, temperature (parallel, perpendicular), dynamic pressure, plasma beta and total speed is symetric when organized as a function of IMF Bz, with one exception, the jet perpendicular temperature and plasma beta. An increased solar wind dynamic pressure seems to correlate to higher values of the jet density but not velocity. We discuss these results in the context of previous similar magnetosheath jet analysis performed on MMS and THEMIS data.

How to cite: Echim, M., Voiculescu, M., Munteanu, C., Voitcu, G., Teodorescu, E., Condurache-Bota, S., Bujor Dănilă, E., and Negrea, C.: Magnetosheath jets and their dynamical properties derived from an analysis of Cluster data at solar minimum (2007,2008), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11573, https://doi.org/10.5194/egusphere-egu22-11573, 2022.

15:43–15:50
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EGU22-1359
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Highlight
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Presentation form not yet defined
Zdenek Nemecek, Jana Safrankova, Kostiantyn Grygorov, Gilbert Pi, Maryam Aghabozorgi Nafchi, Frantisek Nemec, and Jiri Simunek

Comparison of observed magnetopause locations with model predictions can serve as a proof of our understanding of the interaction between solar wind and Earth magnetic field. Since the corresponding upstream conditions are usually derived from observation at L1, our knowledge on solar wind propagation and evolution on short scales are tested as well. We have collected about 40 000 of magnetopause crossings observed by THEMIS spacecraft in course of 2007–2019 years and compared the observed magnetopause position with prediction of several empirical magnetopause models using OMNI upstream parameters (mostly derived from ACE observations) and Wind magnetic field and plasma measurements propagated by our two-step propagation routine. The difference between observed and predicted magnetopause radial distance, Robs – Rmod was used for quantification of the model-observation agreement. We have found that the distribution of Robs – Rmod can be well fitted by the Gaussian distribution with FWHM ≈1.2 Re for all models and both upstream monitors. Nevertheless, the tails of the distributions are enhanced for all models and Robs – Rmod larger than 2 Re are rather frequent. A detailed analysis of such events leads to suggestions for improvement of investigated models or for a building of a new empirical model of the equatorial magnetopause.

How to cite: Nemecek, Z., Safrankova, J., Grygorov, K., Pi, G., Aghabozorgi Nafchi, M., Nemec, F., and Simunek, J.: Extreme magnetopause locations and their sources, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1359, https://doi.org/10.5194/egusphere-egu22-1359, 2022.

15:50–15:57
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EGU22-1366
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ECS
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On-site presentation
Maryam Aghabozorgi Nafchi, Frantisek Nemec, Gilbert Pi, Zdenek Nemecek, and Jana Safrankova

Empirical magnetopause models generally aim to predict its location as a function of upstream solar wind parameters. Many such models have been developed to date, typically based on the fitting of individual magnetopause crossings identified in spacecraft data by prescribed empirical functions deemed to reasonably characterize magnetopause shape and position dependences on selected control parameters. We use a unique list of more than 60,000 magnetopause crossings identified in THEMIS A-E, Magion, Geotail, and Interball spacecraft data to evaluate the performance of some of the most popular such models (Formisano et al., 1979; Petrinec and Russell, 1996; Shue et al., 1997; Lin et al., 2010). Differences between observed and model magnetopause locations are investigated as a function of solar wind dynamic pressure, interplanetary magnetic field magnitude, clock angle, and cone angle. A particular attention is paid to the magnetopause shape. This is studied both in terms of the level of the tail flaring, assuming a rotational symmetry around the aberrated x-axis, and in terms of asymmetries present in the real configuration. We show that although the Lin et al. (2010) model performs arguably the best, some systematic deviations are still present.

How to cite: Aghabozorgi Nafchi, M., Nemec, F., Pi, G., Nemecek, Z., and Safrankova, J.: On the accuracy of selected empirical magnetopause models, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1366, https://doi.org/10.5194/egusphere-egu22-1366, 2022.

15:57–16:04
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EGU22-1733
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ECS
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Presentation form not yet defined
Kostiantyn Grygorov, Zdenek Nemecek, Jana Safrankova, and Jiri Simunek

The magnetopause would be located at a point where the total pressure on the solar wind/magnetosheath side is equal to its magnetospheric counterpart. The upstream pressure is a sum of plasma thermal pressure and magnetic pressure whereas the magnetic pressure would strongly dominate on the magnetospheric side because the density of magnetospheric plasma is typically very low. Statistics of over ten years of THEMIS subsolar magnetopause (YGSM<5 RE) observations reveals that about 2 % of magnetopause crossings exhibit notably higher magnetic field in the magnetosheath than within the magnetosphere and thus the pressure balance is apparently violated. On the other hand, long series of multiple crossings suggest that the magnetopause is close to its equilibrium position and upstream and downstream pressures should be about equal. Interestingly, such crossings were found under both polarities of IMF BZ. In the paper, we study possible sources and mechanisms keeping the pressure balance. We discuss namely the upstream solar wind conditions and state of the outer magnetosphere. Comparison of these unusual magnetopause crossings with the rest of them shows that the cold plasma population coming to the magnetopause from the plasmasphere during periods of geomagnetic storms plays an important role in setting the pressure balance in the magnetopause region.

How to cite: Grygorov, K., Nemecek, Z., Safrankova, J., and Simunek, J.: Pressure balance at the subsolar magnetopause: Statistical study, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1733, https://doi.org/10.5194/egusphere-egu22-1733, 2022.

16:04–16:11
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EGU22-1765
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ECS
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Virtual presentation
Ravindra Desai, Jonathan Eastwood, Joseph Eggington, Jeremy Chittenden, and Richard Horne

Fluxes in the outer radiation belt can vary by orders of magnitude in response to solar wind driving conditions. Magnetopause shadowing, where electron and proton drift paths intersect the magnetopause boundary, is a fundamental loss process which operates on sub-day timescales and can result in rapid loss across the outer radiation belt. Accurate characterisation of this is therefore required to fully account for outer radiation belt dynamics and to avoid unrealistic fluxes impacting long-term forecasts. In this paper we utilise particle simulations of the radiation belts integrated within evolving global MHD simulations, to provide high-resolution high-fidelity simulations of the phenomenon of magnetopause shadowing. We model a variety of magnetopause compression scenarios corresponding to extreme cases of interplanetary shock impacts, and gradual increases in solar wind dynamic pressure. We thus constrain how time-dependent topological variation of the magnetospheric fields results in a complex interplay of open and closed particle drift paths, and examine the role of the electric field in modulating escaping particles trajectories as well as corresponding prompt injections into the inner magnetosphere.

How to cite: Desai, R., Eastwood, J., Eggington, J., Chittenden, J., and Horne, R.: Magnetospheric compressions, magnetopause shadowing and the last-closed-drift-shell, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1765, https://doi.org/10.5194/egusphere-egu22-1765, 2022.

16:11–16:18
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EGU22-3166
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On-site presentation
Stephen Fuselier, Craig Kletzing, Steven Petrinec, Karlheinz Trattner, Don George, Scott Bounds, Rhyan Sawyer, John Bonnell, James Burch, Barbara Giles, and Robert Strangeway

Magnetospheric Multiscale (MMS) observations during an extended crossing of the Earth’s dayside magnetopause show evidence of multiple reconnection at the boundary. This crossing occurred when the IMF was southward and had a significant BY component. Approximately two hours after this crossing, the Twin Rocket Investigation of Cusp Electrodynamics-2 (TRICE-2) rockets were launched into the northern hemisphere cusp and observed overlapping cusp ion injections. These overlapping injections are also evidence of multiple reconnection at the magnetopause. While the observations more than 2 hours apart do not constitute a conjunction between the spacecraft and the rockets, the IMF conditions during the magnetopause crossing and the cusp traversal were very similar. Therefore, had the magnetopause crossings and cusp traversals occurred at the same time, the observations would have been similar. This talk describes these observations and shows the link between multiple reconnection at the magnetopause and overlapping cusp ion injections. In addition, the global consequences on the magnetosphere from this link are discussed.

How to cite: Fuselier, S., Kletzing, C., Petrinec, S., Trattner, K., George, D., Bounds, S., Sawyer, R., Bonnell, J., Burch, J., Giles, B., and Strangeway, R.: Multiple Reconnection X-lines at the Magnetopause and Overlapping Cusp Ion Injections, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3166, https://doi.org/10.5194/egusphere-egu22-3166, 2022.

16:18–16:25
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EGU22-3465
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ECS
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On-site presentation
Kevin Alexander Blasl, Takuma Nakamura, Ferdinand Plaschke, Rumi Nakamura, Hiroshi Hasegawa, Julia E. Stawarz, Yi-Hsin Liu, Sarah A. Peery, Justin C. Holmes, Martin Hosner, Daniel Schmid, Owen Wyn Roberts, and Martin Volwerk

The mass and energy transfer across Earth’s magnetopause is caused by a variety of different plasma processes. One of these processes is the Kelvin-Helmholtz instability (KHI), excited by the velocity shear between the fast-flowing magnetosheath plasma and the relatively stagnant magnetosphere. It has been frequently observed during periods of northward interplanetary magnetic field (IMF), however much less is known about its behaviour during southward IMF conditions.

We present the first Magnetospheric Multiscale (MMS) observations of KH waves and vortices at the dusk-flank magnetopause during southward IMF conditions on September 23, 2017. The instability criterion for the KHI was fulfilled during this event. The boundary normal vectors, obtained by using multi-point methods, are consistent with the predicted structures of the KH waves. We further performed a series of realistic 2D and 3D fully kinetic PIC simulations based on the plasma parameters observed during this MMS event. A comparison to results from these simulations demonstrated quantitative consistencies with the MMS data in many aspects such as the flow and total pressure variations in the KH waves, and the signatures of the non-linearly rolled up KH vortices including the Low Density Faster Than Sheath (LDFTS) plasma.

The simulations further showed that secondary instabilities are excited at the edges of the primary KHI. The Rayleigh-Taylor instability (RTI) can lead to the penetration of high-density arms into the magnetospheric side and disturb the structures of the vortex layer, leading to irregular variations of the surface waves. This can be an important factor in explaining the lower observational probability of KH waves during southward IMF than northward IMF. In the non-linear growth stage of the primary KHI, the lower-hybrid drift instability (LHDI) is excited at the vortex edges leading to efficient plasma mixing across the magnetopause.

The high-time resolution of MMS measurements demonstrated the occurrence of kinetic-scale plasma waves mainly on the low-density side of the edges of the KH waves. Given quantitative consistencies with the simulations, these waves can be interpreted as being generated by the LHDI. These observed waves form due to the strong density gradient between the two sides of the boundary layer and can lead to a flattening of the edge layers.


In this presentation, we will show the consistencies between MMS observations and 2D and 3D simulation runs focusing on the large-scale surface waves (KHI, RTI) and the small-scale fluctuations (LHDI) and outline the multi-scale properties of the observed KH waves during southward IMF.

How to cite: Blasl, K. A., Nakamura, T., Plaschke, F., Nakamura, R., Hasegawa, H., Stawarz, J. E., Liu, Y.-H., Peery, S. A., Holmes, J. C., Hosner, M., Schmid, D., Roberts, O. W., and Volwerk, M.: Multi-scale observations and evolution of the magnetopause Kelvin-Helmholtz waves during southward IMF, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3465, https://doi.org/10.5194/egusphere-egu22-3465, 2022.

16:25–16:32
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EGU22-9701
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Highlight
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On-site presentation
Martin Archer, Joseph Eggington, Michael Hartinger, Michael Heyns, Ferdinand Plaschke, Lutz Rasaetter, Xueling Shi, David Southwood, and Andrew Wright

Surface waves on Earth’s magnetopause act as an efficient mechanism of filtering, accumulating, and guiding the turbulent disturbances present in the solar wind into terrestrial space, thereby playing a key role in controlling global magnetospheric dynamics. However, it is difficult to directly measure these processes since orbiting spacecraft often only provide sparse observation points. It would, therefore, be desirable to be able to remote sense magnetopause surface modes via ionospheric radar or networks of ground magnetometers. The Alfvénic signatures of localised, tailward propagating magnetopause surface waves in ionospheric and ground magnetometer data are somewhat established. However, those associated with the global-scale compressional surface eigenmodes – the lowest frequency and largest-scale normal mode of the magnetospheric system – remain poorly understood. In this presentation we discuss how high-resolution global magnetosphere simulations coupled to an ionosphere model may be able to predict the qualitative features expected in ground-based instruments. Finally, we compare the results of our simulation to simple theory and reported potential observations.

How to cite: Archer, M., Eggington, J., Hartinger, M., Heyns, M., Plaschke, F., Rasaetter, L., Shi, X., Southwood, D., and Wright, A.: What are the ionospheric and ground magnetic signatures of global magnetopause surface modes?, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9701, https://doi.org/10.5194/egusphere-egu22-9701, 2022.

16:32–16:39
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EGU22-5653
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ECS
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On-site presentation
Hongyang Zhou, Lucile Turc, Vertti Tarvus, Yann Pfau-Kempf, Markus Battarbee, Maxime Dubart, Urs Ganse, Markku Alho, Maxime Grandin, Harriet George, Jonas Suni, Maarja Bussov, Konstantinos Papadakis, Talgat Manglayev, Kosta Horaites, Ivan Zaitsev, Giulia Cozzani, and Minna Palmroth

Ultra-low frequency (ULF) waves in the Pc5 range, with periods between 150 – 600 s, play a key role in the dynamics of Earth’s magnetosphere, in particular through their interaction with radiation belt electrons. One important source of magnetospheric Pc5 waves are fluctuations of the upstream solar wind parameters in the same frequency range. Pressure variations in the solar wind are thought to result in a forced breathing of the magnetosphere, as the magnetosphere would expand and compress in response to the changing upstream conditions, which drives ULF waves inside the magnetosphere. The details of the interaction of these solar wind variations with the Earth’s bow shock and magnetosheath, their impact on the magnetosheath plasma properties and how the fluctuations would change before reaching the magnetopause, remain however unclear. In this study, we investigate the influence of externally-driven variations across near-Earth space using global 2D simulations performed with the hybrid-Vlasov model Vlasiator. The new time-varying boundary setup in Vlasiator allows us to set Pc5 periodic density pulses coming from the upstream. The density pulses cause the breathing motion of the bow shock, create clear stripes of variations inside the magnetosheath, and modulate the electromagnetic ion cyclotron (EMIC) and mirror modes. We characterize the spatial-temporal variations of waves on the simulation plane within the magnetosheath and discuss the potential impact on the near-Earth environment.

How to cite: Zhou, H., Turc, L., Tarvus, V., Pfau-Kempf, Y., Battarbee, M., Dubart, M., Ganse, U., Alho, M., Grandin, M., George, H., Suni, J., Bussov, M., Papadakis, K., Manglayev, T., Horaites, K., Zaitsev, I., Cozzani, G., and Palmroth, M.: Magnetospheric Responses to Solar Wind Pc5 Density Fluctuations: Results from 2D Hybrid Vlasov Simulation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5653, https://doi.org/10.5194/egusphere-egu22-5653, 2022.

Coffee break
Chairpersons: Andrey Samsonov, C.-Philippe Escoubet
17:00–17:10
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EGU22-2588
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ECS
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solicited
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Presentation form not yet defined
Imaging the Geospace Via Data-Based Empirical Reconstruction of Magnetospheric Events
(withdrawn)
Varvara Andreeva and Nikolai Tsyganenko
17:10–17:17
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EGU22-2939
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Highlight
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Presentation form not yet defined
Steve Milan, Jenny Carter, Harneet Sangha, Gemma Bower, and Brian Anderson

We quantify the contributions of different convection states to the magnetic flux through-put of the magnetosphere during 2010. To do this we provide a continuous classification of convection state for the duration of 2010 based upon observations of the solar wind and interplanetary magnetic field, geomagnetic indices, and field-aligned currents measured by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE). Convection states are defined as 1) quiet and 2) weak activity, substorm 3) growth, 4) expansion, and 5) recovery phases, 6) substorm driven phase (when relatively steady magnetospheric convection occurs), 7) recovery bays (when recovery phase is accompanied by a negative excursion of the AL electrojet index), and 8) periods of multiple intensifications (storm-time periods when continuous short-period AL activity occur). The magnetosphere is quiet for 46% of the time, when very little convection takes place. The majority of convection occurs during growth and driven phases (21% and 38%, respectively, of open magnetic flux accumulation by dayside reconnection). We discuss these results in the context of the expanding/contracting polar cap model of convection, and describe a framework within which isolated substorms and disturbances during periods of more continuous solar wind-magnetosphere driving can be understood.

How to cite: Milan, S., Carter, J., Sangha, H., Bower, G., and Anderson, B.: Magnetospheric flux throughput in the Dungey cycle: identification of convection state during 2010, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2939, https://doi.org/10.5194/egusphere-egu22-2939, 2022.

17:17–17:24
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EGU22-10242
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ECS
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Presentation form not yet defined
Shannon Hill, Tuija Pulkkinen, Qusai Al Shidi, Austin Brenner, Agnit Mukhopadhyay, Shasha Zou, and Michael Liehmon

We present the first coupled MHD-ring current simulation results that produce the global transpolar auroral arc phenomenon. We examine a unique observation of a midnight transpolar auroral arc that is produced during compressed magnetosphere conditions and persistent into an extended interval of southward IMF and substorm onset. The IMAGE satellite FUV-WIC camera observed the transpolar auroral arc in the southern hemisphere on 15 May 2005. The IMAGE observations show that the transpolar auroral arc originates at 24 MLT and stretches sunward across the polar cap to form a theta aurora with dusk-dawn motion that does not correspond with IMF By sign reversal or continuous magnitude decrease. Even though the theta aurora is typically a northern IMF phenomenon, the IMAGE observations show that the theta aurora persisted for almost an hour under disturbed geomagnetic conditions with peak AL below -1500 nT and Dst around -100 nT. We use the University of Michigan Space Weather Modeling Framework (SWMF) global geospace simulation to study the ionospheric conditions and magnetotail configuration throughout the observation period. Our SWMF simulation results show good agreement with the observed SYM-H and AL indices during the event interval. In the simulation, we identify peaks in Joule heating, precipitation, and anti-sunward flows in the region where the theta aurora is observed. We also demonstrate the temporal evolution of the open-closed field line boundary with respect to the observed theta aurora location, which suggests that the theta aurora is a closed field line phenomenon. We analyze the open-closed field line boundary mapping into the magnetotail and search for causes of precipitation within the simulation as well as analyze the hemispheric conjugacy of the event.

How to cite: Hill, S., Pulkkinen, T., Al Shidi, Q., Brenner, A., Mukhopadhyay, A., Zou, S., and Liehmon, M.: Magnetospheric Source of a Transpolar Auroral Arc: Coupled SWMF Simulation results, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10242, https://doi.org/10.5194/egusphere-egu22-10242, 2022.

17:24–17:31
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EGU22-3173
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Presentation form not yet defined
Joachim Raeder, Beket Tulegenov, William D. Cramer, Banafsheh Ferdousi, Timothy Fuller-Rowell, Naomi Maruyama, and Robert J. Strangeway

It is well known that the polar cap, delineated by the Open
Closed field line Bound ary (OCB), responds to changes in the
Interplanetary Magnetic Field (IMF). In general, the boundary
moves equatorward when the IMF turns southward and contracts
poleward when the IMF turns northward. However, observations of
the OCB are spotty and limited in local time, making more
detailed studies of its IMF dependence difficult. Here, we
simulate five solar storm periods with the coupled
OpenGGCM-RCM-CTIM model to estimate the location and dynamics of
the OCB. For these events, polar cap boundary location
observations are also obtained from Defense-Meteorological
Satellite Pro- gram (DMSP) precipitation spectrograms and
compared with the model output. There is a large scatter in the
DMSP observations and in the model output. However, we generally
find good agreement between the model and the observations. On
average, the model overestimates the latitude of the open-closed
field line boundary by 1.61◦. Additional analysis of the
simulated polar cap boundary dynamics across all local times
shows that the MLT of the largest polar cap expansion closely
correlates with the IMF clock angle; that the strongest
correlation occurs when the IMF is southward; that during strong
southward IMF the polar cap shifts sunward; and that the polar
cap rapidly contracts at all local times when the IMF turns
northward.

How to cite: Raeder, J., Tulegenov, B., Cramer, W. D., Ferdousi, B., Fuller-Rowell, T., Maruyama, N., and Strangeway, R. J.: Polar Cap Boundary Reaction to Geomagnetic Storms, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3173, https://doi.org/10.5194/egusphere-egu22-3173, 2022.

17:31–17:38
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EGU22-3196
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Highlight
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Presentation form not yet defined
Gabor Toth, Xiantong Wang, and Yuxi Chen

The Magnetohydrodynamic with Embedded Particle-In-Cell (MHD-EPIC) model has been developed and applied successfully to Earth, Mercury, Mars and Ganymede magnetosphere simulations. While MHD-EPIC is many orders of magnitude faster than a fully kinetic global model, it can become prohibitively slow if the potential region of interest where kinetic phenomena, such as magnetic reconnection, can occur is large. This is due to the fact that the PIC domain in MHD-EPIC is restricted to a set of static Cartesian boxes. For example, a very large PIC box would be needed to accommodate the flapping motion of the magnetotail current sheet during a geomagnetic storm simulation. To tackle this problem, we have developed a new MHD with Adaptively Embedded Particle-In-Cell (MHD-AEPIC) model. MHD-AEPIC inherits all numerical algorithms from MHD-EPIC and incorporates a new adaptive PIC model, the Flexible Kinetic Simulator (FLEKS). FLEKS allows the PIC cells to be activated and deactivated during a simulation. The coupling between the MHD model and the adaptive PIC grid has been developed and implemented into the Space Weather Modeling Framework. We have also developed physics-based criteria to identify potential reconnection sites, which makes the adaptation fully automatic. In this work, we apply the new MHD-AEPIC model to a geomagnetic storm simulation and demonstrate how adaptation makes this simulation feasible. We compare MHD-AEPIC, Hall MHD and ideal MHD simulation results with each other and with observations ranging from electron scales to global scales. In particular, we demonstrate that MHD-AEPIC is capable of reproducing electron-scale physics in a global simulation.

How to cite: Toth, G., Wang, X., and Chen, Y.: Magnetosphere simulations with ideal MHD, Hall MHD and the MHD with Adaptively Embedded Particle-in-Cell (MHD-AEPIC) models, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3196, https://doi.org/10.5194/egusphere-egu22-3196, 2022.

17:38–17:45
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EGU22-5549
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ECS
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On-site presentation
Austin Brenner, Tuija Pulkkinen, Gabor Toth, Qusai Al Shidi, and Mike Liemohn

The solar wind couples with Earth’s magnetosphere driving plasma dynamics which can create magnetic perturbations at Earth’s surface impacting life on the ground. One classic way of understanding this process is via the Dungey cycle where magnetic flux is injected into the magnetosphere on the dayside via a dayside reconnection site. This flux is then transported downstream and is released from the magnetosphere via a tail reconnection site, bringing high hydrodynamic energy plasma earthward which becomes trapped in the ring current, leading to intense sustained magnetic perturbation.

In this work, we take a closer look at this process using 3D MHD results from the Space Weather Modeling Framework. Building off previous work by Brenner et al. 2021, the magnetopause surface is identified in the simulation domain to a fixed downstream tail distance. This 3D volume is then split into regions based on magnetic topology and L shell location. From here two methods are used to describe the magnetic perturbation resulting from each region. The first is using the Biot-Savart law that integrates current density vectors weighted by position and direction. The second uses the virial theorem which employs the scalar product of momentum with the position vector integrated over the magnetosphere. The latter formulation is advantageous since it directly relates the magnetic perturbation with stress terms at the magnetopause boundary and volume integrated energy density in the magnetosphere.

Results from the Biot Savart integration and virial theorem are compared with observations of ground based magnetic perturbations to study the effects of energy transport within the system during a simulated storm event.

How to cite: Brenner, A., Pulkkinen, T., Toth, G., Al Shidi, Q., and Liemohn, M.: Using the Virial Theorem to Analyze Effects of Energy Dynamics in the Magnetosphere, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5549, https://doi.org/10.5194/egusphere-egu22-5549, 2022.

17:45–17:52
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EGU22-3573
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Highlight
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Virtual presentation
Minna Palmroth, Urs Ganse, Yann Pfau-Kempf, Markku Alho, Jonas Suni, Maxime Grandin, Lucile Turc, Markus Battarbee, Andreas Johlander, Vertti Tarvus, Hongyang Zhou, Maarja Bussov, Maxime Dubart, Harriet George, Konstantinos Horaites, Talgat Manglayev, Konstantinos Papadakis, Rumi Nakamura, and Tuija Pulkkinen

Among the most unpredictable phenomena within the near-Earth space are substorms, periods of energy loading and explosive release within the magnetospheric tail. Substorms are global, as energy is extracted from the solar wind via dayside reconnection, while the tail energy release takes place in a vast domain within a few tens of seconds. Due to the scarcity of space-borne observations, it has been difficult to conclusively separate between the onset scenarios that include magnetic reconnection and various ion-kinetic instabilities, which occur at mesoscales, and small scales. Another decades-long investigation concerns the flapping of the plasma sheet, occurring within a large area favouring the substorm growth phase, although it has been observed at other times as well. Mechanisms to explain the flapping are presently unknown. Modelling efforts have failed to explain the substorm onset either because all the required physics has not been included in the simulation, or the simulation does not cover the entire domain, thus possibly missing important drivers. Vlasiator is a  model describing the global magnetosphere accurately at ion-kinetic scales, including the ion-kinetic effects that are absent in the fluid descriptions. Unlike many other kinetic simulations, Vlasiator extends the simulation domain to global scales and accurately represents the Earth’s unscaled magnetosphere from the dayside to the tail, in six dimensions including the 3D real space and 3D velocity space without noise that is present in the alternative PIC method. We present the first global 6D simulation encompassing the entire near-Earth space to simulate ion-kinetic magnetospheric dynamics self-consistently. We determine reconnection, ion-kinetic instabilities, plasma sheet flapping, and bursty bulk flows in the simulation domain, and show how they all contribute to the whole and work in concert in developing the substorm onset. Our results help to understand spacecraft measurements and the overall substorm process, which will significantly improve understanding space physics and eventually space weather. Our results can also be used in strategies to design a mission, which will finally and conclusively capture the substorm onset with in situ measurements.

How to cite: Palmroth, M., Ganse, U., Pfau-Kempf, Y., Alho, M., Suni, J., Grandin, M., Turc, L., Battarbee, M., Johlander, A., Tarvus, V., Zhou, H., Bussov, M., Dubart, M., George, H., Horaites, K., Manglayev, T., Papadakis, K., Nakamura, R., and Pulkkinen, T.: Substorm onset and current sheet flapping in a 6D global ion-kinetic simulation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3573, https://doi.org/10.5194/egusphere-egu22-3573, 2022.

17:52–17:59
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EGU22-3429
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ECS
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Presentation form not yet defined
Maxime Dubart, Markus Battarbee, Urs Ganse, Felix Spanier, Jonas Suni, Andreas Johlander, Markku Alho, Maarja Bussov, Giulia Cozzani, Harriet George, Maxime Grandin, Talgat Manglayev, Kostis Papadakis, Yann Pfau-Kempf, Vertti Tarvus, Lucile Turc, Ivan Zaitsev, Hongyang Zhou, and Minna Palmroth

Numerical simulations play a central role in modern sciences. The trade-off between the accuracy of the physical processes described and the cost of computational resources is often the main limiting factor in these simulations. In global hybrid-Vlasov simulations, such as Vlasiator, lowering the spatial resolution in order to save on resources can lead to key processes being unresolved. A previous study has shown how insufficient resolution of the proton cyclotron instabilities leads to a misrepresentation of ion dynamics. This leads to larger temperature anisotropy and loss-cone shaped velocity distribution functions. In this study, we present a numerical model to introduce pitch-angle diffusion in velocity space, at a spatial resolution where this process was previously not correctly resolved. We test two different methods to enable pitch-angle diffusion in the 3D cartesian velocity space of Vlasiator. We show that we are successfully able to isotropise loss-cone shaped velocity distribution functions, and that this method could be applied to large simulations in order to save computational resources and still correctly model the Earth's magnetosheath.

How to cite: Dubart, M., Battarbee, M., Ganse, U., Spanier, F., Suni, J., Johlander, A., Alho, M., Bussov, M., Cozzani, G., George, H., Grandin, M., Manglayev, T., Papadakis, K., Pfau-Kempf, Y., Tarvus, V., Turc, L., Zaitsev, I., Zhou, H., and Palmroth, M.: Subgrid modelling of pitch-angle diffusion for ion-scale waves in a global hybrid-Vlasov simulation, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3429, https://doi.org/10.5194/egusphere-egu22-3429, 2022.

17:59–18:06
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EGU22-7611
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ECS
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Highlight
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Virtual presentation
Maxime Grandin, Thijs Luttikhuis, Markku Alho, Markus Battarbee, Maarja Bussov, Giulia Cozzani, Maxime Dubart, Urs Ganse, Harriet George, Konstantinos Horaites, Talgat Manglayev, Konstantinos Papadakis, Yann Pfau-Kempf, Jonas Suni, Vertti Tarvus, Lucile Turc, Ivan Zaitsev, Hongyang Zhou, and Minna Palmroth

The precipitation of charged particles from the magnetosphere into the ionosphere is one of the crucial coupling mechanisms between these two regions of geospace. While precipitating particle fluxes have been measured by numerous spacecraft missions over the past decades, it often remains difficult to obtain global precipitation patterns with a good time resolution during a substorm. Numerical simulations can contribute to bridge this gap and help improve the understanding of mechanisms leading to particle precipitation at high latitudes through the global view they offer on the near-Earth space system. We present the first results on proton precipitation within a 3-dimensional simulation of the Vlasiator hybrid-Vlasov model. The run is driven by southward interplanetary magnetic field conditions with steady solar wind parameters. We analyse the large-scale proton precipitation pattern in both hemispheres and discuss its dynamics in relation to the processes taking place in the magnetotail.

How to cite: Grandin, M., Luttikhuis, T., Alho, M., Battarbee, M., Bussov, M., Cozzani, G., Dubart, M., Ganse, U., George, H., Horaites, K., Manglayev, T., Papadakis, K., Pfau-Kempf, Y., Suni, J., Tarvus, V., Turc, L., Zaitsev, I., Zhou, H., and Palmroth, M.: Proton precipitation in a hybrid-Vlasov simulation with southward interplanetary magnetic field driving: First 3D results, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7611, https://doi.org/10.5194/egusphere-egu22-7611, 2022.

18:06–18:13
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EGU22-1177
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ECS
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On-site presentation
Laura Fryer, Robert Fear, Imogen Gingell, John Coxon, Minna Palmroth, Sanni Hoilijoki, Pekka Janhunen, and Anita Kullen

We investigate the dynamic coupling between the solar wind and Earth’s magnetosphere during northward IMF conditions. The high latitude lobe regions of the magnetosphere during such conditions are generally characterised as containing cool, very low energy plasma populations. However, when the solar wind is directed northward, hot plasma populations can sometimes be observed within the lobes, and transpolar arcs (auroral features which extend from the nightside into the polar cap) can also be present. We discuss three cases in which the Cluster spacecraft observed uncharacteristically energetic plasma populations in the lobe, with the footprint of the spacecraft intersecting a transpolar arc (Fryer et al., 2021). These observations reveal that both the hot plasma populations, and therefore transpolar arcs, are likely to form on closed field lines and are consistent with a mechanism in which magnetotail reconnection builds up closed field lines within the magnetotail, which then become “stuck” in the lobe (Milan et al., 2005).

Under certain northward IMF conditions, we find that the Grand Unified Magnetosphere-Ionosphere Coupling Simulation (GUMICS) model reproduces a similar large, closed field line region in the magnetotail. We find similarities between the structures seen within the simulation runs, the results of the in-situ observational study, and the Milan et al. (2005) magnetotail reconnection model, but also note some key differences in the configuration of the magnetotail reproduced in the simulations, compared with the remote and in situ observations. Finally, we note that the SMILE spacecraft will be ideally positioned to observe the coupling between the solar wind and Earth’s magnetosphere during northward IMF conditions, through both high latitude in situ observations and imaging of the auroral response.

How to cite: Fryer, L., Fear, R., Gingell, I., Coxon, J., Palmroth, M., Hoilijoki, S., Janhunen, P., and Kullen, A.: Observations and simulations of northward IMF magnetotail structure, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1177, https://doi.org/10.5194/egusphere-egu22-1177, 2022.

18:13–18:20
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EGU22-6954
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Presentation form not yet defined
Reham Elhawary, Karl Laundal, Jone Reistad, Anders Ohma, Spencer Hatch, and Sara Gasparini

Substorms that occur under northward interplanetary magnetic field (IMF) conditions can elucidate the relationship between the dayside and nightside dynamics of the ionosphere. We investigate the relationship between the dayside and the nightside dynamics in response to northward IMF substorms. While the dynamics of the dayside ionosphere are directly related to the interaction between the solar wind interplanetary magnetic field (IMF) and the earth’s magnetic field, the dynamics in the nightside are strongly controlled by magnetotail activity like substorms. Under southward IMF conditions, both reconnection on the dayside and substorms on the nightside increase Dungey convection, making it difficult to distinguish the separate contributions of dayside and nightside processes to large-scale dynamics. Under northward IMF conditions, on the other hand, it is easier to distinguish between dayside and nightside processes, since northward IMF does not increase Dungey flows. We present a superposed epoch analysis of the equivalent current and magnetic perturbations above 60 deg magnetic latitude (mlat) from ground-based magnetometer stations based on 280 northward IMF substorms. We also investigate whether the dayside current pattern is influenced by the substorm onset.

How to cite: Elhawary, R., Laundal, K., Reistad, J., Ohma, A., Hatch, S., and Gasparini, S.: The relationship between dayside and nightside Dynamics under northward interplanetary magnetic field substorms, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6954, https://doi.org/10.5194/egusphere-egu22-6954, 2022.

18:20–18:27
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EGU22-7637
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ECS
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On-site presentation
Sara Gasparini, Karl M. Laundal, Jone P. Reistad, Anders Ohma, Spencer Hatch, and Reham Elhawary

The solar wind’s embedded interplanetary magnetic field (IMF) impinging on the Earth’s magnetosphere has an impact on the terrestrial environment. The primary mechanism which allows for direct interaction between the solar wind and the terrestrial environment is magnetic reconnection on the Earth’s dayside between the IMF and the Earth’s magnetic field. Changes in the IMF result in a change of magnetic reconnection rates at the Earth’s dayside leading to changes in the auroral oval morphology/topology. The auroral oval is rather dynamic, and its variability is currently not well understood. We hypothesise that much of this variability is due to variations in ionospheric convection. We interpret its temporal and morphological variability in terms of ionospheric convection and dayside and nightside reconnection rates, (i.e., the "expanding/contracting polar cap" paradigm). Dayside reconnection is responsible for opening magnetic flux on the dayside and initiating ionospheric flows whereas nightside reconnection is ensuring closure of open magnetic field lines. In this study we infer convection patterns with SuperDARN (Super Dual Auroral Radar Network) measurements and ground-based magnetometers data (SuperMAG) using a new data assimilation technique. We combine convection flows with auroral precipitation patterns and solar wind parameters to understand the behavior of the auroral oval and the physical mechanisms that drive its dynamical changes. By examining both the dynamic evolution of the ionospheric convection and the corresponding dynamics of the colocated auroral forms seen in global UV images, we investigate to what extent convection can be associated with the changes observed in the large scale auroral boundaries in selected events. 

How to cite: Gasparini, S., Laundal, K. M., Reistad, J. P., Ohma, A., Hatch, S., and Elhawary, R.: The role of ionospheric convection in shaping the auroral oval, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7637, https://doi.org/10.5194/egusphere-egu22-7637, 2022.

Presentations: Fri, 27 May | Room L1

Chairpersons: C.-Philippe Escoubet, Andrey Samsonov
08:30–08:37
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EGU22-12309
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On-site presentation
Adrian Grocott and Maria-Theresia Walach

We use an 18 year database of Super Dual Auroral Radar Network (SuperDARN) data to investigate the morphology of the large-scale ionospheric convection pattern. In particular, we look statistically at the location of the foci of the dawn and dusk convection cells which, according to the theoretical picture of Cowley and Lockwood (1992), are expected to move towards the dayside (nightside) when the Dungey cycle is dominated by magnetopause (magnetotail) reconnection. We use concurrent observations of the solar wind and interplanetary magnetic field to provide a proxy for the level of magnetopause reconnection and ground magnetic indices such as AL to provide an indication of the expected level of magnetotail reconnection. We find that, on average, the cell foci do move as predicted by the theory, but the presence of significant variability is consistent with additional factors being involved in governing the convection morphology at any given instant.

Cowley, S. W. H., and M. Lockwood (1992), Excitation and decay of solar wind-driven flows in the magnetosphere-ionosphere system, Ann. Geophysicae, 10, 103-115.

How to cite: Grocott, A. and Walach, M.-T.: Morphology of the ionospheric convection pattern during time-dependent solar wind and magnetospheric driving, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12309, https://doi.org/10.5194/egusphere-egu22-12309, 2022.