EGU21-9370
https://doi.org/10.5194/egusphere-egu21-9370
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Subgrid modelling of ion pitch-angle scattering for magnetosheath waves in a global hybrid-Vlasov simulation

Maxime Dubart1, Urs Ganse1, Adnane Osmane1, Andreas Johlander1, Markus Battarbee1, Markku Alho1, Maarja Bussov1, Harriet George1, Maxime Grandin1, Kostis Papadakis1, Yann Pfau-Kempf1, Jonas Suni1, Lucile Turc1, and Minna Palmroth1,2
Maxime Dubart et al.
  • 1University of Heslinki, Department of Physics, Helsinki, Finland (maxime.dubart@helsinki.fi)
  • 2Space and Earth Observation Centre, Finnish Meteorological Institute, Helsinki, Finland

Numerical simulations are widely used in modern space physics and are an essential tool to understand or discover new phenomena which cannot be observed using spacecraft measurements. However, numerical simulations are limited by the space grid resolution of the system and the computational costs of having a high spatial resolution. Therefore, some physics may be unresolved in part of the system due to its low spatial resolution. We have previously identified, using Vlasiator, that the proton cyclotron instability is not resolved for grid cell sizes larger than four times the inertial length in the solar wind, for waves in the downstream of the quasi-perpendicular shock in the magnetosheath of a global hybrid-Vlasov simulation. This leads to unphysically high perpendicular temperature and a dominance of the mirror mode waves. In this study, we use high-resolution simulations to measure and quantify how the proton cyclotron instability diffuses and isotropizes the velocity distribution functions. We investigate the process of pitch-angle scattering during the development of the instability and propose a method for the sub-grid modelling of the diffusion process of the instability at low resolution. This allows us to model the isotropization of the velocity distribution functions and to reduce the temperature anisotropy in the plasma while saving computational resources.

How to cite: Dubart, M., Ganse, U., Osmane, A., Johlander, A., Battarbee, M., Alho, M., Bussov, M., George, H., Grandin, M., Papadakis, K., Pfau-Kempf, Y., Suni, J., Turc, L., and Palmroth, M.: Subgrid modelling of ion pitch-angle scattering for magnetosheath waves in a global hybrid-Vlasov simulation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9370, https://doi.org/10.5194/egusphere-egu21-9370, 2021.

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