Comparison Analysis of Two Warm Sector Torrential Rain Weathers on the East Side of Tibetan Plateau

Two warm sector torrential rain processes in 12 ~ 13 Aug,2010(“8 · 12 ”) and 16 ~ 17 Aug,2012(“8·16”) between the east side of Tibetan Plateau and the Sichuan Basin are analysed based on the conventional observation data,precipitation data of automatic weather stations and NCEP 1°×1° reanalysis data. The similar and different features of weather conditions are compared. The results indicate that there is no cold air but warm low pressure near the surface and West Pacific subtropical high at 500 h Pa before the two torrential rains occur and also in the process,the atmospheric were have unstable stratification and high energy. Two processes have the same trigger mechanisms,which includes the diabatic heating at complex terrain,the warm advection in the lower in the Sichuan Basin and orography dynamic lifting. Meanwhile,the main difference between two warm sector processes is the southeast wind in the lower. In the “8 ·16 ”process the southeast wind comes from the northeastern of Typhoon KAITAK,which have longer influence time and more northward than “8 · 12 ”process. The warm advection in the lower,orography dynamic lifting and torrential rain have the same Characteristics of the southeast wind. Analyzing those two processes,it is found the key point to the warm sector torrential rain systems between the east side of Tibetan Plateau and the Sichuan Basin lie in the building,enhancement and maintaining of the southeast wind in the lower.