[P-EM11] Space Weather and Space Climate

[PEM11-18] Space Weather at Mars as Probed by Topside Radar Sounding

★Invited Papers

*原田 裕己¹、中村 勇貴²、Sánchez-Cano Beatriz³、Lester Mark³、寺田 直樹⁴、Leblanc Francois⁵ (1.京都大学、2.東京大学、3.レスター大学、4.東北大学、5.LATMOS/CNRS)

キーワード：火星、宇宙天気、レーダー

Characterization and assessments of the radio environment at Mars have been increasingly important as human exploration of Mars becomes closer to reality. One of the key factors controlling the planetary radio environment is the ionosphere of the planet. The ionosphere of Mars may appear benign at first glance because its peak electron density and total electron content are roughly an order of magnitude lower than those of the terrestrial ionosphere. Meanwhile, recent observations by spaceborne remote and in-situ instruments indicate the presence of strong radio absorption and wide spatial scales of ionospheric irregularities, both of which can be enhanced during space weather events. However, their practical effects on radio communication have not yet been evaluated, and to do so, we would need observationally validated numerical models capable of reproducing the variability of the Martian ionosphere. The growing volume of observational data on the Martian space environment obtained by the recent Martian missions provides a great opportunity to explore the capability and limitation of new sophisticated numerical models. We present an initial effort of such a data-model comparison focusing on the radio absorption in the nightside ionosphere of Mars as well as a brief review of recent progress in observations of the spatiotemporal variability of the Martian ionosphere.