抄録
This research aims to investigate the growth stage of cumulus cloud before the occurrence of Guerilla-heavy rainfall (GHR) using the rapid scan observation of Himawari-8, which has fine temporal and spatial resolutions. For our goal, we utilized Rapid Development Cumulus Area (RDCA) index for earlier detection of first echo aloft (baby-rain cell). As our research focuses on the development of small-scale cloud, we eliminated parallax problem in Himawari-8 observation. We overlaid 16 cases of brightness temperature (TB; Band 13) of Himawari-8 and composite radar observational data. Based on the distance between cloud and rain cell centers in two images, we retrieved the linear equation to solve the parallax effect. The correctness of relocated cloud was confirmed by comparing the estimated top heights of cloud and precipitation. The displacement vector of TB was applied to solve parallax effect for Band 03 visible channel and RDCA index. In this research, we modified the usage of RDCA index from lightning prediction to the baby-rain cell prediction of GHR. The original RDCA index, ranging from 0.1 to 0.9 was used to detect the early signal in cloud development process to predict the occurrence of baby-rain cell. By analyzing some case studies we confirmed that detailed RDCA index can predict the occurrence of baby-rain cell of GHR.
