@inproceedings{oai:jaxa.repo.nii.ac.jp:00019824,
 author = {田口, 堅士 and 野口, 克行 and 齊藤, 昭則 and 大塚, 雄一 and 津川, 卓也 and 小山, 孝一郎 and Taguchi, Kenji and Noguchi, Katsuyuki and Saito, Akinori and Otsuka, Yuichi and Tsugawa, Takuya and Oyama, Koichiro},
 book = {大気圏シンポジウム第17回　平成14年度, Atmospheric Science Symposium the 17th 2002},
 month = {},
 note = {GPS衛星から送信される2周波の電波の伝搬遅延から、全電子数(Total Electron Content: TEC)が求まる。TECとは、衛星と受信機を結ぶ伝播経路上に含まれる電子の積分値であり、1m(sup 2)に含まれる電子の数で表される。このデータには各送信・受信機の持つバイアスが含まれている。このバイアスを最小2乗法で推定することにより、TECの絶対値を算出することができる。日本には現在、国土地理院により約1,000点の受信機(GEONET: GPS Earth Observation NETwork)が配置されており、30秒という高時間分解能、緯度・経度0.15度という高空間分解能でTECを求めることができる。本研究は絶対値TECの基本的な振る舞いを調べることを目的として、1999年5月〜2002年12月のTEC絶対値の経験的モデルを作成し、統計的解析を行った。地方時・太陽活動度・季節の各依存性を求めた。電離圏トップサイドの影響を見積もるためにNmF2との比較を行った。また、冬季夜間においてTEC絶対値の異常増加が観測された。この原因究明のため、IGS受信局との比較から考察を行っていく。GEONETの密なデータを利用した、絶対値TECの統計的解析は世界初の試みである。, Empirical models of the Total Electron Content (TEC) over Japan are developed with GPS-based observations to investigate fundamental behavior of absolute TEC. The network of about 1,000 GPS receivers, which are installed by the Geographical Survey Institute (GSI), realizes the dense mapping of TEC over Japan. Recently, many researches using TEC are made. TEC is practically used to evaluating the influence of the earth ionosphere in satellite communication. However, the statistical analysis and models of absolute TEC with GEONET was not made so far. Since absolute TEC is an integration value along the ray path, it differs from the behavior of maximum electron density of the F2 layer (NmF2), which is obtained with Ionosonde. TEC is influenced from compositions of bottomside of the ionosphere, neutral winds of topside of the ionosphere, and the plasmasphere. Therefore, more information is included in TEC than NmF2. However, the many features of TEC still remain to be studied. Statistical analyses of absolute TEC of Japan from May 1999 to December 2002 are performed. Dependence of the TEC variation is investigated on the local-time, season and 10.7-cm solar flux index (F 10.7). The contribution of topside of ionosphere is discussed in a comparison of NmF2. Seasonal anomaly and equinoctial asymmetry of electron density in the ionosphere observed with the Ionosonde and MU radar has been confirmed using TEC derived from the GPS data. However, the season to take the maximum of TEC and NmF2 differs slightly. Anomalous nighttime increase in a TEC was observed in winter. These increases appear mainly in high and mid-latitude and are discussed in a comparison of international GPS service (IGS) data., 資料番号: AA0045981027},
 pages = {102--105},
 publisher = {宇宙科学研究所, The Institute of Space and Astronautical Science (ISAS)},
 title = {GEONETを用いたTEC絶対値の統計的解析:(1)基本的様相と(2)異常現象},
 year = {2003}
}