Japan Geoscience Union Meeting 2018

Presentation information

[EE] Oral

P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM13] Study of coupling processes in solar-terrestrial system

Sun. May 20, 2018 10:45 AM - 12:15 PM 304 (3F International Conference Hall, Makuhari Messe)

convener:Mamoru Yamamoto(Research Institute for Sustainable Humanosphere, Kyoto University), Yasunobu Ogawa(National Institute of Polar Research), Satonori Nozawa(名古屋大学宇宙地球環境研究所, 共同), Akimasa Yoshikawa(Department of Earth and Planetary Sciences, Kyushu University), Chairperson:Ogawa Yasunobu, Nozawa Satonori

11:30 AM - 11:45 AM

[PEM13-08] Temperature variations in the D- and E-region polar ionosphere during stratospheric sudden Warming

*Yasunobu Ogawa1, Satonori Nozawa2, Masaki Tsutsumi1, Yoshihiro Tomikawa1, Chris Hall4, Ingemar Haggstrom 3 (1.National Institute of Polar Research, 2.ISEE, Nagoya University, 3.EISCAT HQ, 4.UiT The Arctic University of Norway)

Keywords:polar ionosphere, EISCAT, D-region ionosphere

We analyzed ion temperature and velocity observed by the European Incoherent Scatter (EISCAT) UHF radar at Tromsoe (69.6 deg N, 19.2 deg E) during a stratospheric sudden warming (SSW) that occurred in January-February, 2017. The zonal ion velocities at 85-100 km height reversed approximately 8 days earlier than the zonal wind reversal in the upper stratosphere and the ion temperature at 85-95 km decreased simultaneously with the zonal ion velocity reversal at the same altitude. We found that the time variations of ion temperature in the daytime are close to those of neutral temperature derived from the ambipolar diffusion coefficients obtained with the Nippon/Norway Tromsoe Meteor Radar (NTMR) data at the same altitude even when geomagnetic activity is moderate. This suggests that the D- and lower E-region ion temperature in the daytime is a good proxy for neutral temperature at the same altitude. We will explain the reliable ion temperature derivation in the D-region and its limitation, and also discuss relationship between ion temperature and vertical ion velocity variations at 85-95 km measured with the EISCAT UHF radar.