最新型二偏波ドップラーレーダーを用いた降水量推定精度の向上

Abstract

降雨量推定精度向上を目指した偏波レーダーの研究は20年前から国内外で始められ，わが国では国土交通省釈迦岳レーダ雨量計として1992年に現業化されている。しかし，技術開発黎明期であったため，大幅な精度向上に至らなく，現業化への研究は終了した。この様な中，本研究は，国土交通省の現業レーダーの今後の偏波化を視野に入れ，最先端のCバンド偏波レーダの観測精度を，ディスドロメータによる雨滴粒径分布の観測情報を利用して検証し，偏波パラメータと雨滴粒径分布の関係，さらに偏波パラメータと降水強度の関係を通じてその有意性について検証した後，降水強度推定精度向上の可能性を示す。

Dual polarimetric radar has been developed and partly utilized in meteorology and hydrology in these twenty years because its potential ability in estimating drop size distribution (DSD) and in discriminating precipitation type. Meantime, Ministry of Infrastructure, Land and Transportation (MILT) in Japan put Shakadake operational C band Radar practical use in 1992. However, large improvement had not been realized because of its initial technical stage. Under these circumstances, this study investigates observation precision of the latest C band polarimetric radar for promoting replacement of Japanese operational radars into operational polarimetric Doppler radars. As results, this study shows ZHH, ZDR and KDP observed by the polarization radar well fit to non-parametrically computed ZHH, ZDR and KD using observed DSD, respectively. However, KDP has a little bias. Also, this study shows ""Radar observed ZDR～Dm of observed DSD” relation is consistent with observed DSD. Parameter from the polarization radar has high possibility to improve real-time rainfall estimation.