Diagnostic Analysis and Numerical Simulation of a Rainstorm in June 14—15,2002

A diagnostic analysis of a rainstorm process during June 14—15,2005 is performed based on the NCEP/NCAR reanalysis data,and the simulation of the process is conducted using the meso-scale MM5 model with the assimilation of cloud-derived wind data.The results show that the strengthening of a high-level jet stream and its momentum downward-spreading impelled the maintenance of the low-level jet,and the coupling of the high-and low-level jets provided a proper dynamical condition for the occurrence and development of the torrential rain process.The abundant and stable vapor supply to the rainstorm process mainly originated from the Indian Ocean.The effects of cloud-derived wind assimilation were examined in sensitive experiments;the wind,temperature,geopotential height fields are more significantly improved in the experiment with the cloud-derived wind assimilation of two time levels than those in that with one time level assimilation,thus the predicted physical variable and rainfall fields in the former are closer to the observed fields than in the latter.