Cause Analysis of "2008.5.2" Strong Sandstorm in the Eastern of Hexi Corridor

Using the conventional detection,ground intension observation,vorticity relation system and T213L19 amount prediction product and FY-2c/2d infrared satellite cloud image data,the weather power diagnosis and mesoscale analysis are carried on causes of gale and strong sandstorm weather process in east of Hexi corridor on May 2,2008.The results show that the strong sand storm following ground cold front is primary cause of strong sandstorm occurring.Step and ladder short wave troughs of 500 hPa provides great criterion circulation background for development of sandstorm.Distortion field of 700 hPa is triggering system of gale and sandstorm.Development of ground thermal low pressure enlarges gradient of pressure and temperature before and after cold front,by which thermal instability condition is provided for convection development.Deep vertical circulation development condition is provided by secondary circulation of upper jet stream entrance region on the south side for deep convection development,which is basic power of sand storm occurring.The basic energy is provided by momentum flux caused by strong ground friction wind for the sand and dust rolling-up.The basic condition of form potential energy into kinetic energy is provided by strong instability stratification for convective development.The vertical helicity has good instruction significance for landing region of sandstorm.