[P-EM06] Mesosphere-Thermosphere-Ionosphere Coupling in the Earth's Atmosphere

[PEM06-16] 電離層E領域のCa+密度とF領域の中規模伝搬性電離圏擾乱の初同時観測

*江尻 省¹、津田 卓雄²、西山 尚典¹、阿保 真³、西岡 未知⁴、丸山 隆⁴、齊藤 昭則⁵、中村 卓司¹ (1.国立極地研究所、2.電気通信大学、3.首都大学東京大学院システムデザイン研究科、4.（独）情報通信研究機構、5.京都大学大学院理学研究科地球物理学教室)

キーワード：共鳴散乱ライダー, カルシウムイオン, 中規模伝搬性電離層擾乱, GPS-TEC, スポラディックE層

In the mesosphere and lower thermosphere region, there are permanent layers of metal atoms and ions, the source of which is vaporization of cosmic dust and meteoroids during their entry into the Earth's atmosphere. Some metal atom layers e.g. Na, K, Ca, and Fe layers, and only Ca⁺ (Calcium ion) can be observed by ground-based resonance scattering lidars. The National Institute of Polar Research (NIPR) is developing a new resonance scattering lidar system with a frequency-tunable laser. The lidar transmitter is based on injection-seeded, pulsed alexandrite laser for 768-788 nm and a second-harmonic generation (SHG) unit for 384-394 nm. The new lidar is able to measure density variations of minor constituents including Ca⁺ (393.477 nm). As a part of the development, observation tests are carried out at NIPR (35.7N, 139.4E) since 2013, and we got the first light from Ca⁺ layer on 21 August, 2014. The Ca⁺ density profiles were obtained for 〜5 hours (23:13 LT-28:28 LT) with temporal and height resolutions of 1 min and 15 m, respectively. During the night, high density and narrow Ca⁺ layer was observed. The layer descended from 〜107 km to 99 km with quasi-periodic density perturbations until 〜17 UT and then stayed at around 99 km until sunrise. At the same night, sporadic E (E_s) layer was observed with an ionosonde at Kokubunji by National Institute of Information and Communications Technology (NICT) (35.7N, 139.5E), also medium scale traveling ionospheric disturbances (MSTIDs) were observed with the dense GPS receiver network (GEONET). In this presentation, we compare these data in detail and discuss relationships between observed Ca+ density perturbations, E_s layer and MSTIDs