テイキドウ エイセイ ト チジョウ GPS ジュシンキモウ ノ TEC データ デ カンソク サレタ SED ノ コウド コウゾウ

低軌道衛星搭載GPS 受信機と地上GPS 受信機網の電離圏全電子数(Total Electron Content; TEC)データを用いて,地磁気擾じょうらん乱時に北半球電離圏において赤道異常帯から北西方向へ高電子密度領域が細長く伸びる現象,Storm-enhanced density(SED)の電子密度高度構造の解明を行った.本研究では北米大陸でSED が発生していた2 つの事例に対し,Gravity Recovery and Climate Experiment(GRACE)衛星搭載のGPS 受信機による高度500?20000 km のTEC データ(GRACE-TEC)と,地上-GPS 衛星間TEC データを用いて,SED の観測を行った.その結果,2 つのSED を観測し,GRACE-TEC データでは,地上-GPS 衛星間TEC データよりも3-5° 程度高い緯度でSED が観測されることが明らかになった.これは,SED の低緯度側では高度500 km以上にあるプラズマは高度500 km 以下にあるプラズマの? 程度であるが,SED の高緯度側では高度500 km 以上にあるプラズマは高度500 km 以下にあるプラズマの1.1-2.7 倍であり,SED 内部において,高緯度ほど高い高度にプラズマ密度が増加しているためである.このような緯度-高度構造は,SED 内部の増加した東向き電場によるE×B ドリフトによるものと解釈される.The altitudinal structure of Storm-enhanced density (SED) was studied using the Total Electron Content (TEC) data of the GPS receiver on the Gravity Recovery and Climate Experiment (GRACE) satellite and the ground-based GPS receivers. The GRACETEC-data are derived from the GPS receiver on the GRACE satellite. A SED is a high-electron density phenomenon that extends from the Equatorial Ionization Anomaly (EIA) toward the north-west in the northern hemisphere during geomagnetic disturbed time. TwoSEDs were observed as TEC variations in the GRACE-TEC data and in the ground-GPS TEC data. The ground-GPS TEC data is the TEC data between the ground GPS receiver and the GPS satellites. The SED observed in the GRACE-TEC data appeared at higher latitudes than that in the ground-GPS TEC data. We concluded detected that the altitudinal structure of the SED would be different between at lower than at higher latitudes due to the effects of the eastward E×B drift

Analysis of the altitudinal structure of Storm-enhanced density using Total Electron Content data of space-borne and ground-based GPS receivers

The altitudinal structure of Storm-enhanced density (SED) was studied using the Total Electron Content (TEC) data of the GPS receiver on the Gravity Recovery and Climate Experiment (GRACE) satellite and the ground-based GPS receivers. The GRACETEC-data are derived from the GPS receiver on the GRACE satellite. A SED is a high-electron density phenomenon that extends from the Equatorial Ionization Anomaly (EIA) toward the north-west in the northern hemisphere during geomagnetic disturbed time. TwoSEDs were observed as TEC variations in the GRACE-TEC data and in the ground-GPS TEC data. The ground-GPS TEC data is the TEC data between the ground GPS receiver and the GPS satellites. The SED observed in the GRACE-TEC data appeared at higher latitudes than that in the ground-GPS TEC data. We concluded detected that the altitudinal structure of the SED would be different between at lower than at higher latitudes due to the effects of the eastward E×B drift