MESOSCALE CHARACTERISTICS AND CAUSES OF TROPICAL STORM FITOW(0114) HEAVY RAIN

With PSU/NCAR nonhydrostatic mesoscale model MM5,the rainfall process of tropical storm Fitow(0114) is simulated for 00UTC31 Aug. -00UTC2 Sept. 2001, Mesoscale dis-creting is performed on the results with filtering scheme. Analyses show that the MM5 model well reproduced the position and intensity of heavy rain. Mesoscale characteristics of heavy rain were well represented in rainfall time scale, rainfall area, stream field and divergence at lower and upper levels. The interaction between inverted typhoon trough and these mesoscale systems lead to heavy rain occurrence. The distribution of divergence fields at lower and upper levels can have a kind of indication for the rainfall. Heavy rain are affected by topography and coast in South China. Weak instability is favorable to the generation of heavy rain.