[P-EM13] 太陽地球系結合過程の研究基盤形成

[PEM13-09] Horizontal temperature gradients in the polar upper mesosphere and lower thermosphere above Tromsoe, Norway

*野澤 悟徳¹、川原 琢也²、津田 卓雄³、藤原 均⁴、斎藤 徳人⁵、和田 智之⁵、小川 泰信⁶、高橋 透⁶、三好 勉信⁷、Hall Chris⁸、Brekke Asgeir⁸ (1.名古屋大学宇宙地球環境研究所、2.信州大学工学部、3.電気通信大学情報理工学研究科、4.成蹊大学理工学部、5.理化学研究所光量子工学研究領域、6.国立極地研究所、7.九州大学大学院理学研究院地球惑星科学部門、8.ノルウェー北極大学UiT)

キーワード：空間温度勾配、極域MLT領域、ナトリウムライダー、EISCAT、トロムソ

Based on about 2700 hours of temperature data obtained with the Tromsoe sodium LIDAR, we have investigated horizontal temperature differences (i.e. temperature gradient) in the polar MLT region between October and March. The sodium LIDAR operated at the EISCAT Tromsoe site (69.6 deg. N, 19.2 deg. E) has a capability of simultaneous five-beam observations; i.e. temperature and sodium density data are obtained simultaneously with good time and altitude resolutions (3 min/500m). In addition to vertical observations, the sodium LIDAR observed volumes of four different directions with azimuth and elevation of (0 deg., 77.5 deg.), (90 deg., 77.5 deg.), (180 deg., 77.5 deg.), and (270 deg., 77.5 deg.) between October 2013 and March 2017, while the elevation angle of 60 degree was set between October 2012 and March 2013, and between October 2017 and March 2018. These configurations allow us to derive horizontal temperature difference between about 80 and 107 km.

We have analyzed (so far) about 184 nights of temperature data sets. The horizontal temperature gradient is found to be in range from about 0.5 K/km to -0.5 K/km for northward and eastward directions, and on average (nighly mean) in range from about 0.05 K/km to -0.05 K/km. We will report temporal and altitude variations of the tempetarure gradient, changes of nightly mean temperature gradients in accordance with SSWs, and comparison with GAIA calculations.