关键词: 雨夹雪转暴雪天气, 微物理过程

Abstract: Based on the nonhydrostatic mesoscale model MM5 with the Reisner graupel scheme in four nested domains, the rain and snow becoming heavy snow process on February 12 and 13, 2009 was simulated in Liaoning province, and microphysical process within cloud was analyzed, especially the source terms of rain, snow and graupel. The results indicate that the collisions between rain and snow and between rain and cloud water both are the main microphysical process forming rain. The increased rain mainly occurs under 700 hPa. Deposition growth of snow from 300 hPa to 200 hPa, the automatic transformation from ice crystal to snow and the collision between rain and snow under 900 hPa are the mainly microphysical process of increase of snow. The automatic transformation from ice crystal to snow is important to the increase and the maintenance of snowfall. At last, three levels cloud structures and the microphysical model are presented in this process.