低纬高原地区2次强寒潮过程对比分析

COMPARATIVE ANALYSIS OF TWO STRONG COLD WAVE PROCESSES IN LOW LATITUDE PLATEAU AREA

通过对云南2次强寒潮过程进行对比分析,结果表明:横槽型和北脊南槽型是2次过程的主要中高纬环流形势;横槽型造成的降温范围更广,强度更强,持续时间更强,但降雪除了很大程度受制于冷空气外,还受到水汽和动力抬升条件的影响;北脊南槽型冷空气相对横槽型弱一些,但当配合强盛的南支槽,高原切变线,及高低空急流耦合作用下导致了暴雨强降雪天气; 2次强降雪过程云南西侧都有充沛的水汽输送,水汽通量的增大是云南强降雪的必备条件;中低层来自孟加拉湾的暖湿气流在云南南部形成能量积集区和强烈的水汽辐合区,在低层辐合、中高层辐散的耦合作用下,形成强烈的对流上升运动,为强降雨提供了动力和水汽条件;雨转雪相态变化过程中当地面出现"冷垫"一般指示降雪的出现。

Through the comparison and analysis of two strong cold wave processes in Yunnan, the results show that, the transverse groove type and the northern ridge south groove are the main middle and high latitude circula- tion situation of the two processes. Transverse groove cooling is wider, stronger intensity, duration, but in addi- tion to much snow is subject to the cold air outside, still under the influence of water vapor and power lifting con- dition, north ridge south trough the weak cold air relative transverse groove, but when cooperate with strong southern trough, the plateau shear line, and high and low air jet under coupling action led to the heavy rain heavy snow weather; There are abundant water vapor transmission on the western side of Yunnan, and the increase of water vapor flux is the necessary condition for strong snow in Yunnan. Warm moist air flows from the bay of Ben- gal in the lower formation energy product set in the south of Yunnan area and intense water vapor convergence zone, in the lower convergence and upper divergence, under the coupling effect of the formation of strong con- vective upward movement, the power and water vapor conditions for heavy rainfall; A ＂cold cushion＂ appears in the local area during the change of the snow.