Numerical Simulation and Stratification Structure Analysis of Freezing Rain Event in Guizhou in January 2008

Abstract

Severe freezing rain disaster has happened in Guizhou Province early 2008. The meso-scale maintenance mechanism of the stationary front related to the event is analyzed from the aspects of circulation,low er jet and moisture transportation. And as typical case,the third process which is the most devastating one in the event has been simulated through WRF model. The results consist with observations in circulation pattern,precipitation distribution and intensity. High resolution simulation clearly reflects stratification structure of stationary front and distribution characteristics of cloud substances over freezing rain area in Guizhou. The research shows that except the general three-layer structure(includes ice layer,warm layer and cold layer),the typical two-layer structure of freezing rain also appeared in central region of Guizhou. This means freezing rain may develop merely when a deep warm moist layer that has temperature exceed 0℃ in middle altitude overruns a colder layer,while solid particles in upper air hardly exist. Abundant liquid drops contain in warm layer fall through shallow colder layer forming supercooling raindrops,and freeze on contact with surface.