[P-EM09_29AM2] VarSITI - Variability of the Sun and Its Terrestrial Impact

[PEM09-34] 高解像度GPS全電子数観測を利用した電離圏研究

*津川 卓也¹、西岡 未知¹、齊藤 昭則²、大塚 雄一³、石井 守¹ (1.情報通信研究機構、2.京都大学大学院理学研究科、3.名古屋大学太陽地球環境研究所)

キーワード：電離圏, GPS, 全電子数, 熱圏

Two-dimensional total electron content (TEC) observations using dense GPS receiver networks have been applied to studies of various ionospheric disturbances since mid-1990s. For the purpose of monitoring and researching the ionospheric disturbances, we have developed high-resolution TEC maps using dense GPS receiver networks. We have been collecting all the available GNSS receiver data in the world to expand the TEC observation area. These GNSS data are provided by IGS, UNAVCO, SOPAC, and other regional data centers. Currently, we are providing global and regional maps of absolute TEC, detrended TEC, and rate of TEC change index (ROTI). These data and quick-look maps are archived and available in DRAWING-TEC website (http://seg-web.nict.go.jp/GPS/DRAWING-TEC/). These high-resolution GPS-TEC maps have been applied to studies of various ionospheric disturbances. Sudden increase in TEC caused by solar flares were studied using global TEC observations. Regional TEC observations have revealed new characteristics of large- and medium-scale traveling ionospheric disturbances (LSTIDs and MSTIDs). Recently, clear concentric waves and short-period oscillations were observed after huge earthquakes/tsunamis and massive tornadoes, indicating that acoustic and/or gravity waves propagate upward from the lower atmosphere and reach the ionosphere. These GPS-TEC observations will contribute the next SCOSTEP program VarSITI, particularly to the ROSMIC (Role Of the Sun and the Middle atmosphere/thermosphere/ionosphere In Climate) project.