2012年12月20-23日巴州寒潮降雪天气的特征分析

Characteristic analysis of the cold wave and snowfall in 20-23 December 2012 in Bayingolin Mongol Autonomous Prefecture

摘要:

利用常规观测资料、自动站、T639网格零场资料，采用天气学原理和天气动力学诊断分析方法，对2012年12月20-23日巴州寒潮天气过程的成因和降雪天气特征进行分析，并给出降雪天气概念模型。结果表明：这次寒潮降雪过程是北欧阻塞高压向东南衰退，导致脊前横槽转成竖槽东南移，使高空锋区南压至4０癗附近，造成巴州强降温、强降雪等寒潮天气，在连续降雪时段700hpa上主要影响系统是700hpa冷暖切变线和辐合风场，水汽主要源自中低层西北方的径向和低层东南方的维向输送；后面的冷凝降雪和阴雪天气局地特征明显，水汽来源于850hpa至近地层局地的垂直输送，与巴州冬季降雪从近地层到低层空气湿度近似饱和条件有直接关系。

Abstract:

Based on the conventional observation data, automatic weather station and T639 forecast products，in terms of the synoptic principle and dynamic diagnosis，the causation of cold wave and the character of snow during 20-23 December 2012 has been analyzed。 The results are as follows：The cold wave occurred when the North European backup ridge broken up southeastwards， leading transverse trough to erect trough which moved southeastwards。Sharp edge of high temperature was about 4０癗 which brought the strong decline of temperature and snowfall。The influencing system during snowing was the shear line between cold air mass and warm air mass as well as the mesoscale wind convergence。Water vapor was derived from northwestwards which radial moved and southeastwards which latitudinal moved。There was distinct local character tail condensation snowing and overcast and snowy moment which water vapor derived from the local vertical moving。The results showed that the saturation of moisture conditions in boundary layer were very important for winter snowfall .