Extended Abstract

The mechanism analysis of cloud and moisture sources/sinksin the formation of torrential rainfallJinhai HE 1 , Shouting GAO 2 , and Luan XU 3Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing Universityof Information Science &Technology 1 , Laboratory of Cloud-Precipitation Physics andSevere Storms, Institute of Atmospheric Physics, Chinese Academy of Sciences 2 ,Department of Atmospheric Sciences, Nanjing University of Information Science&Technology 3Moisture and cloud s ources/sinks are the two main aspects that contribute totorrential rainfalls. While moistu re proc ess is most import ant associated wit hprecipitation, cloud sources/sinks s hould not be neglected. During rainfall,there are intense convective activities in the clouds. Convergence in the lowerlayer forces the ascending motion, and divergence occurs on top of clouds.This outward divergent flow can generate downdraf ts all around. Thedowndrafts encounter the warm moist air at the bottom of the clouds, unst ablestratification forms, then triggers new conv ections. All the convective cloud smay join together , resulting in more in tense rainfall. Thus, more attentionshould be paid on cloud process.In this study, surface rain rate formul ation with cloud sources/sinks is applied.By use of the dat a based on Jap an re gional spectral model, the cloudsources/sinks are analyzed in rainfall ev ents during Meiyu period. This termcan modify the surface rain rate calculated based on the moisture sink,especially when during the light rainfa ll event s. The inc lusion of clo udsources/sinks favors quantit ative calculation of the surface rain rate, and thisformulation has considerable potential in the quantit ative precipit ationestimation.-67-