SIMULATION AND ANALYSIS OF MESO-B VORTEX OVER MIDDLE REACHES OF THE YANGTSE RIVER ON 22 JULY 1998

By using mesoscale model MMS,we have successfully simulated two meso-β vortexes responsible for the heavy rainfall nearby Wuhan on 22 July 1998.One of the two meso-β vortexes is centered at Lushan,and the other is at Huanggang. Both of them are in the lower troposphere. Although there are only 100 km between them,two meso-β vortexes have different structures and different causes. The low-level jet disturbance is the basic cause for Lushan meso-β vortex. Three hours after it occurred,Lushan vortex causes the formation of Huanggang vortex by its secondary circulation.