Kaバンド雲レーダー等のマルチセンサーで捉えた積乱雲の生成・発達過程

Abstract

Suddenly-generated and rapidly-developed isolated cumulonimbus often cause flash flood and inundation disasters. For these disasters prediction, it is significant to analyze flow structure in a cumulonimbus cloud before raindrop generation. To investigate the initiation process, we conducted observation in Kobe City, on August 2018 using a Ka-band Doppler radar, X-band radars and some sensors. Developing cumulonimbus clouds and non-precipitating cumulus were observed by Ka-band radar, and the former has high Radar reflectivity (Zh) in the upper part. This implies that strong updraft lifted up the cloud particles and particle size grew up in the developing cell. In addition, we evaluated the effect of spatial resolution and direction on the radar observation by analyzing the vortex structure simulated by a Large Eddy Simulation model. The simulation result show that the vorticity can be observed irrespective of the direction if a cell has a circulation in a spatial scale larger than observation.