Microphysical process simulation of a snowstorm freezing rain in the middle and lower reaches of the Yangtze River,China

Based on NCEP(1°×1°) reanalysis data and conventional observation data,the snowstorm freezing rain process from 25 to 29 in January 2008 was simulated by WRF model in the middle and lower reaches of the Yangtze River.The results indicate that the evolution characteristics of the upper and lower air circulation and precipitation belt distribution in this process can be simulated well by WRF model.The transportation of warm moist air by middle level southwest jet and persistent diffusion of low level cold air provide the temperature stratification conditions for snowstorm and freezing rain.The analysis on the cloud microphysical process indicates that there is multiple cloud systems precipitation in this process.The strong inversion layer especially 0 ℃ layer from 600 hPa to 850 hPa makes snow and ice phase particles melt into super-cooling water,which results in the large range freezing rain.At the same time,it is the important condition for the large range snowstorm freezing rain formation.