2012年12月20-23日巴州寒潮降雪天气的特征分析

利用常规观测资料、自动站、T639客观分析资料,结合天气学原理和天气动力学诊断分析方法,对2012年12月20-23日巴音郭楞蒙古自治州（以下简称巴州）的寒潮天气过程的成因和降雪天气特征进行分析,并给出巴州降雪天气概念模型。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,高空冷空气南压至40°N附近,造成巴州强降温、强降雪等寒潮天气,降雪阶段关键影响系统是700 hPa上的冷暖切变和风场辐合,水汽主要源自中低层西北方的经向和低层东南方的纬向输送;后续的冷凝降雪和阴雪阶段天气局地特征明显,水汽源自850 hPa至近地层局地的垂直输送。

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

Based on the data from conventional observation, automatic weather station and T639forecast products, in terms of the synoptic principles and dynamic diagnosis, the causation of coldwave and the weather characteristics of snowfall during December, 20th-23rd 2012 have beenanalyzed. The results are as follows. The cold wave occurred when the north European backup ridgebroken up southeastwards, leading transverse trough to turn into longitudal trough which movedsoutheastwards. Sharp front in the high atmosphere was at about 40°N which brought the strongdecline of temperature and snowfall. The influencing system during snowing was the shear linebetween cold air mass and warm air mass as well as the mesoscale wind convergence. Water vaporwas derived from northwest moving longitudinally and southeastwards moving atitudinally. There wasdistinct local characteristics of condensation snowing, and overcast and snowy moment when watervapor vertically moved in the local region. The results showed that the saturation of moistureconditions in boundary layer were very important for winter snowfall.