[A-AS13] ミクロスケール気象現象解明にむけた稠密観測・予報の新展開

[AAS13-12] スキャン型Kaバンドドップラーレーダとステレオ写真測量による山岳上の積乱雲発生過程の観測

★招待講演

*三隅 良平¹、櫻井 南海子¹、前坂 剛¹、鈴木 真一¹、清水 慎吾¹、岩波 越¹ (1.防災科学技術研究所)

It is known that convective storms are frequently initiated over mountains in warm and humid environment. According to previous studies, shallow cumuli initiated over heated mountains develop into a deep convective storm. However, the transition process from shallow to deep convection is not well understood due to a lack of observation data. In order to elucidate this problem, we observed convective clouds initiated over mountains in Kanto, Japan on 18 August 2011 using a 35 GHz scanning Doppler radar and a pair of digital cameras. The first cloud observed over the mountains reached the 6 km level, while the maximum echo-top height was about 1 km lower than the cloud top. The maximum radar reflectivity in the cloud was about 10 dBZ found around the 2 to 3 km levels. The reason why the echo-top altitude was lower than the cloud-top height was considered to be due to the mixing with surrounding dry air. After such shallow cumuli appeared three times repeatedly, a deep convective cloud developed. These results are consistent with a "pre-conditioning" hypothesis, that shallow cumuli moisten midlevel air and produce favorable condition for development of deep convective storms.