Causation Analysis of Heavy Rain Process during 7—8 June 2006 in Sanming

Using data of the conventional observation,physical parameters,satellite cloud images and hourly precipitation,a heavy rain process occurring in Sanming area during 7—8 June,2006 was analyzed.The results have shown that the dynamic and thermodynamic conditions for the beginning and development of the heavy rain process were provided by a South China low-level jet.The main weather systems which brought about the heavy rain process were an upper-level trough,a South China low level vortex shear, and a surface stationary front.The positions where the heavy rain happened were:①between the 850hPa low-level vortex shear and the surface stationary front,②near the 850hPa moisture tongue area and dense isoline area of moisture flux,③near—10·10~(-5)g·hPa~(-1)·cm~(-2)·s~(-1) valued center of moisture flux divergence field at 700hPa,④the location of index K greater than 34℃,⑤the stronger flow ascending district in the vertical velocity field.The strength and location of the heavy rain were closely related to the mesoscale disturbances.The heavy rain process was caused by three easterly moving mesoscale rain clusters and three meso-βcloud clusters.