Comparative Analysis of Two Regional Cold Wave Synoptic Process in Sichuan

Using the NCEP 1°×1° 6h reanalysis data and observation data,this paper research the synoptic characteristics of the two regional cold wave events by synoptic principle and dynamic diagnosis in Sichuan. The results showed that: (1) the two process are the type of Central Asia transversal trough cold wave(N-type),In the early stage,meridional circulation strengthens at the middle and high latitudes,explosively development of Ural blocking high,the cold air behind trough and the warm air before Southern Branch Trough meet over Sichuan Basin, causing the cold wave synoptic process. (2) Two cold wave synoptic process occurred with higher - than - normal temperature before the process,help the falling of temperature. (3) The southwest lower-level jet,which transports moisture to the Sichuan Basin,continuous precipitation is one of the causes of strong cooling. (4) The cold advection from 850hPa is the key factor of the cold wave,there is a good correspondence between the mobile path and intensity center of cold advection and the process cooling area.