Liaoning Region Rainstorm Numerical Simulation Of Severe Convective Weather And Diagnostic Analysis

A heavy rain process occurred in Liaoning area during Aug. 5-6, 2003 is studied in this paper. Based on synoptic maps and radar data analysises, the north-China cyclone is regarded as the major influnce synoptic system for the heavy rain process. The short wave trough development caused the cold air moved southward, and the stationary subtropical high, as well as the low level jetstream carrying warm and moist air are the important factors for the cycloginisis and development of the north-China cyclone. The structure of the forward-tilted trough increases the atmospheric instability and caused the severe convective weather. Radar echoes are in mixing type. The zero velocity isoline well indicates the formation and development of the cyclone.For further investigating the causes of the cyclone development, a numerical simulation by using MM5 and a diagnostic analysis based on the outputs of the model have been done. The results showed that, the dry intrusion causes the cyclone increase;the secondary circulation plays a role of trigger mechanism; and the helicity distribution well corresponding to the precipitation.