利用NCEPGFS资料分析了2007年1月15—16日鄂东南地区降雪过程,对造成暴雪过程的天气系统发生、发展背景场进行分析。并利用中尺度数值天气模式WRF模拟了这次暴雪过程,探讨了其发生发展的机制。天气系统的背景分析表明,这次暴雪过程主要是受700hPa西南急流和地面冷空气的共同影响而产生的,降水过程与西南急流的变化密切联系。WRF模式较好地再现了此次暴雪的过程。模拟结果表明西南急流的减弱和移出,对应着降雪的开始和停止;在西南急流的左侧,由于低层涡度的增加,使低空辐合、高空辐散,在连续性原理和动力机制约束下导致上升运动的加强是该次暴雪的形成机制。模式结果说明,产生暴雪的上升运动要远小于产生暴雨的上升运动,且在暴雪过程中,中层为上升运动,近地层和高层伴随着下沉运动。
Using the Global Forecast System (GFS) analysis data from the National Centers for Environmental Prediction (NCEP) , the synoptic feature was analyzed for a snowstorm occurred in Southeast Hubei from January 15 to 16, 2007. The mesoscale model of Weather Research and Forecasting (WRF) was used to forecast this snowstorm and the mechanism of the snowstorm was analyzed. The large-scale circulation shows that the snowfall resulted from the southwest jet at 700 hPa in conjunction with cold air on the surface. Snowstorm processes were highly associated with the movement of the southwest jet. The WRF model can simulate well the snowstorm. The results show that the onset and end of the precipitation corresponded to the movement of the southwest jet. In the left side of southwesterly jet, it is the increased low level vorticity that caused low-level convergence and high -level divergence , then caused ascending motion to strengthen, therefore, the snowstorm occurred. Furthermore, the results showed the difference of the vertical motion between heavy rain and blizzard.