Japan Geoscience Union Meeting 2019

Presentation information

[J] Oral

P (Space and Planetary Sciences ) » P-CG Complex & General

[P-CG25] Planetary Magnetosphere, Ionosphere, and Atmosphere

Tue. May 28, 2019 9:00 AM - 10:30 AM A05 (TOKYO BAY MAKUHARI HALL)

convener:Kanako Seki(Graduate School of Science, University of Tokyo), Takeshi Imamura(Graduate School of Frontier Sciences, The University of Tokyo), Hiroyuki Maezawa(Department of Physical Science Osaka Prefecture University), Naoki Terada(Graduate School of Science, Tohoku University), Chairperson:Masaki Nishino(名古屋大学宇宙地球環境研究所), Hiroyuki Maezawa(大阪府立大学大学院理学系研究科)

9:45 AM - 10:00 AM

[PCG25-02] Transport and energization of planetary ions in the magnetospheric flanks of Mercury

*Sae Aizawa1, Dominique Delcourt2, Naoki Terada1 (1.Graduate School of Science,Tohoku University, 2.LPC2E, CNRS)

Keywords:Non-adiabatic energization, Mercury's magnetosphere, FIPS/MESSENGER, Kelvin-Helmholtz instability

The transport and energization of planetary ions within Kelvin-Helmholtz (KH) vortices developing in the magnetospheric flanks of Mercury are investigated using both numerical methods and data analysis. Due to the presence of heavy ions of planetary origin (e.g., O+, Na+, and K+) and the complicated field structure present during the KH vortex development, the scale of electric field variations can be comparable to that of the ion gyromotion. Therefore, ions may experience non-adiabatic energization as they drift across the magnetopause. In this study, we focus on the effects of the spatial/temporal variations of the electric field along the ion path. We show that the intensification, rather than the change in orientation, is responsible for large non-adiabatic energization of heavy ions of planetary origin. This energization systematically occurs for ions with low initial energies in the direction perpendicular to the magnetic field. The energy gain is of the order of the energy corresponding to the maximum ExB drift speed. It is also found that the ion transport across the magnetopause is controlled by the orientation of the magnetosheath electric field. Analyzing data from MESSENGER allow us to compare the observational facts with our numerical results. We find that the counts of Na+-group detected by FIPS increase with the existence of KH waves, which is consistent with our numerical results. Although some differences in the energy distribution are expected in our numerical results, the data show no significant differences. This will be the subject of further studies using the newly developed BepiColombo instruments.