[P-EM15] Study of coupling processes in solar-terrestrial system

[PEM15-08] Statistical study of high energy electron precipitation based on Arase satellite - EISCAT collaborative observation data

*Yasunobu Ogawa¹, Mizuki Fukizawa¹, Yoshizumi Miyoshi², Keisuke Hosokawa³, Shin-ichiro Oyama², Kazuo Shiokawa², Kanako Seki⁴, Satoshi Kurita⁵, Kazushi Asamura⁶, Satoshi Kasahara⁴, Takefumi Mitani⁶, Shoya Matsuda⁷, Yoshiya Kasahara⁷, Yuto Katoh⁸, Iku Shinohara⁶ (1.National Institute of Polar Research, 2.ISEE, Nagoya University, 3.The University of Electro-Communications, 4.University of Tokyo, 5.RISH, Kyoto University, 6.ISAS, Japan Aerospace Exploration Agency, 7.Kanazawa University, 8.Tohoku University)

Keywords:Ionosphere, EISCAT, ERG, Arase

We have conducted more than 150 collaborative observations (~600 hours in total) between the Arase (ERG) satellite and EISCAT radar since March 2017. The obtained collaborative observation data have been used to publish papers based on detailed data analysis on high-energy electron precipitation into the arctic ionosphere and molecular ion upflow from the arctic ionosphere. However, the overall characteristics of many collaborative events have not been systematically analyzed and summarized.
In this paper, we report statistical results of the relationship between wave and particle data observed by the Arase satellite and ionospheric electron density data obtained with the EISCAT Tromsø radar. Their results are summarized as follows:
(1) When the amplitude of the lower-band chorus (LBC) waves is above ~18 pT, magnetospheric electrons with energies above ~160 keV undergo pitch angle scattering, and become significantly ionized at altitudes between 65-100 km.
(2) The relationship between resonance energies of pitch angle scattering and electron density increases due to energetic electron precipitation suggests that pitch-angle scattering of energetic electrons by LBC waves propagating at higher latitudes (~20 deg) rather than in the magnetic equatorial plane occurs frequently.