2016年1月重庆市大范围降雪天气过程成因分析

On Analysis of the Cause of the Extensive Snowfall Event in January 2016 in Chongqing

利用常规观测资料、地面加密观测资料及NCEP 1°×1°再分析资料,对2016年1月重庆地区大范围降雪天气过程的成因进行了分析,并探讨了降水相态的转换过程.结果表明:高层的横槽转竖和低层的切变线南下,引导强冷空气影响重庆,是此次降雪天气过程的主要成因,但上升运动和水汽辐合较弱,降雪量偏小.对流层低层的高湿区对应降雪落区,即重庆中西部、东南部地区.强冷空气造成大范围的降温,地面气温降至1℃以下,是雨转雪的主要条件.

Based on the conventional observational data,the dense surface observational data,and NCEP(1°×1°)reanalysis data,the Extensive Snowfall Event in January 2016 in Chongqing have been analyzed。The results show that the snowfall is mainly related to the strong cold air which influence Chongqing,when the high-level horizontal trough turn to longitudinal one and the low-level shear line move southward。Because the updrafts and vapor convergence are weak,the snowfall is weak.The snowfall area of this event is in the middle,western and southeastern Chongqing,which correspond to the high humidity area in the low-level.The strong cold air is main condition that causes rain to snow,when surface air temperature drops below 1℃.