Upper Atmosphere Cooling Investigated by Precipitating Particles

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04052
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17010:Space and planetary sciences-related
• Research Institution: National Institute of Polar Research
• Principal Investigator: Yasunobu Ogawa 国立極地研究所, 共同研究推進系, 教授 (00362210)
• Co-Investigator(Kenkyū-buntansha): 加藤 雄人 東北大学, 理学研究科, 教授 (60378982)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 超高層大気 / 降下粒子 / 電離圏 / 寒冷化

Outline of Final Research Achievements

In order to quantitatively understand various long-term variations in the polar upper atmosphere, we conducted (1) a detailed investigation of upper atmosphere ionization associated with electron precipitation to the earth and (2) investigations of long-term variations in polar ionospheric ion temperature based on European Incoherent Scatter (EISCAT) radar data.
Numerical simulation results show that (1) the maximum collision rate in the altitude range lower than 100 km becomes one order of the magnitude smaller depending on the effect of the mirror force on the electron precipitation. As for (2), the characteristics of ionospheric cooling can be estimated with higher accuracy using 43 years of EISCAT radar data, and differences in the characteristics of ionospheric cooling/warming depending on the season and altitude are also clarified.

Free Research Field

超高層物理学

Academic Significance and Societal Importance of the Research Achievements

（１）の研究成果については、波動粒子相互作用によるピッチ角散乱に起因する高エネルギー電子の降下による電離圏応答の精密なモデル化において、ミラーフォースの重要性を示唆するものである。（２）の研究成果については、下層大気から熱圏までを包括する全大気圏における気候変動の理解と将来予測に貢献する内容である。