EGU22-3573, updated on 08 Jan 2024
https://doi.org/10.5194/egusphere-egu22-3573
EGU General Assembly 2022
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Substorm onset and current sheet flapping in a 6D global ion-kinetic simulation

Minna Palmroth1,2, Urs Ganse1, Yann Pfau-Kempf1, Markku Alho1, Jonas Suni1, Maxime Grandin1, Lucile Turc1, Markus Battarbee1, Andreas Johlander3, Vertti Tarvus1, Hongyang Zhou1, Maarja Bussov1, Maxime Dubart1, Harriet George1, Konstantinos Horaites1, Talgat Manglayev1, Konstantinos Papadakis1, Rumi Nakamura4, and Tuija Pulkkinen5
Minna Palmroth et al.
  • 1University of Helsinki, also at: Finnish Meteorological Institute, Helsinki, Finland (minna.palmroth@helsinki.fi)
  • 2Finnish Meteorological Institute, Space and Earth Observation Center, Helsinki, Finland
  • 3Swedish Institute of Space Physics, Uppsala, Sweden
  • 4Space Research Institute, Austrian Academy of Sciences, Graz, Austria
  • 5Department of Climate and Space Sciences and Engineering, University of Michigan, Michigan, USA

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.