A diagnose and mesoscale analysis of a torrential rain process in Jiangsu province

Based on black body temperature data of FY-2E meteorological satellite,Doppler radar images and NCEP reanalysis data,combining the intensive observation of automatic weather station data,a diagnose and mesoscale analysis of the torrential rain along Yangtze river basin in Jiangsu province on July 12-13,2010 was performed.The results show that the heavy rainfall occurred in the favorable and stable environmental conditions and had the feature of obvious mesoscale.Convergence at the low-level,divergence at the upper level and vertical helicity provided dynamic mechanism for the rainstorm process.Upward flow of vertical cell of ageostrophic wind and vertical velocity could trigger the instable energy to be released.A frequent activity of ten rain clusters directly brought about the torrential rain.And the mergered rain clusters called A and B played an important role in heavy rainfall process,and which led to larger rain area coverage,stronger rain intensity and longer life span.Three β-MCS continued to occur in Jiangsu one after another during the course of rainstorm.It deserves extra attention that the development of rain clusters was directly associated with central cold cover in which the temperature fell below-62 ℃,even lower than-72 ℃.The process of heavy rainfall appeared in the area of adverse wind and of the echo clusters merging.The surface mesoscale convergence system had close links with rain clusters and had good indication for rain clusters forecast.