2010年冬季浙江两次强降雪过程的对比分析

利用NCEP1°×1°再分析资料,对浙江2010年冬季两次强降雪过程的环流形势和物理量场进行了分析和讨论.结果表明:两次过程都是北方冷空气与西南暖湿气流交汇所致,冷空气较强时,锋区迅速南压,降雪持续时间较短,暴雪产生在中低层切变线的风速辐合区中；而冷空气强度适中时,“冷垫”和静止锋长时间存在,降雪持续时间则较长,暴雪产生在低空急流的左前方；降雪区上空有明显的水汽通量辐合,水汽通量大值区的演变与降雪过程有较好的对应关系；低空辐合和高空辐散的配置是强降雪产生的有利动力条件,其强度越强,降雪也越强.

Contrast Analysis of Two Heavy Snowfall Events in Zhejiang

Based on the NCEP 1°×1° reanalyzed data, the circulation situation and physics fields of two heavy snowfall events in Zhejiang during the winter of 2010 were analyzed. The results have shown that: (1) The two heavy snowfalls are caused by the intersection of north cold air and southwest warm moist flow. The duration of snowfall is short when the cold air is strong, because the front zone moves southward quickly. The heavy snowfall occurred in the convergence area of wind velocity of shear lines in the middle and low levels. (2) The cold air of moderate intensity makes the cold layer and the stationary front exist for a long time. This is an important condition for long duration snowfall. The heavy snowfall occurred in the front of low level jet on the left side. (3) There is strong convergenc of vapor flux over snowfall region. The relationships between the variation of large value area of vapor flux and the snowfall process are significant. (4) It is the favorable dynamic condition for heavy snowfall that there are convergence in the lower level and divergence in the upper level. The intensity of snowfall increases with the intensity of lower level convergence and upper level divergence.