川西高原东部两次连续强降雪过程对比分析  

Comparative Analysis of two Consecutive Heavy Snowfall Processes in the Eastern Part of the Western Sichuan Plateau

作　　者：武敬峰 刘静颖 张永莉[3] 

机构地区：[1]阿坝州松潘县气象局,四川松潘623300 [2]阿坝州马尔康市气象局,四川马尔康624000 [3]成都信息工程大学大气科学学院,四川成都610225

出　　处：《成都信息工程大学学报》2017年第6期651-661,共11页Journal of Chengdu University of Information Technology

基　　金：国家青年科学基金资助项目(4105077)

摘　　要：针对2016年2月21-23日和2017年2月21-22日川西高原东部连续强降雪过程进行分析,利用NCEP再分析资料、常规高空、地面、云图资料对环流背景场和物理量场分析研究,结果表明:降雪前期500 h Pa为高原槽或西风槽配合有高空锋区影响,700 h Pa在甘肃南部有切变南下,地面上为冷高压扩散到高原,后期为南北槽叠加形式。中低层水汽源地都在孟加拉湾,前期水汽通量强,比湿大,后期水汽通量弱,比湿小,但低层受偏东水汽通量与地形抬升关系,结合500 h Pa的弱水汽辐合使降雪持续。降雪时都出现了较强的垂直上升运动,这与地形抬升有一定关系,其上升高度与降雪强度之间存在关系。降雪前期湿位涡MPV1中高层都为正值,低层为负值区,到后期低层转为弱的正值区,而MPV2则正好相反;云图上3次降雪在01-02时开始,都有云团合并加强,黑体亮温梯度明显增加时出现降雪,且小时降雪量较大。According to the analysis of 21-February 2016 23 and February 2017 21-22 days in eastern Sichuan Plateau continuous heavy snowfall process,analysis of the circulation background and the physical quantity field research data analysis,the conventional surface and upper data,and NCEP satellite data were used.The results show that the front of the snow is a plateau trough or a westerly trough,and it has the influence of the high-altitude front zone. The southern part of the 700 h Pa is sheared southward in the south of Gansu,and the cold high pressure on the ground diffuses to the plateau,and the later is the superposition of the north and south trough. Low level moisture source in the bay of Bengal,early water vapor flux,high humidity,water vapor flux over late weak,small,but the low layer East water vapor flux and the topography,combined with water vapor convergence of 500 h Pa,makes continuous snowfall. When snow falls,there is a strong vertical upward movement,which is related to the elevation of terrain,and there is a relationship between the rising height and the intensity of snowfall. The wet snow is positive vorticity in high MPV1,low level negative area to the late low layer to weak positive region,and MPV2 is just the opposite.The satellite pictures of 3 snow begins at 1 to 2 o＇clock,and there are clouds with enhanced snowfall TBB gradient increasing obviously,and in the hour there is a large amount of snow.

关 键 词：气象学 高原气象学 连续性强降雪 地形强迫抬升 水汽通量 比湿 垂直速度 湿位涡 

分 类 号：P458.121[天文地球—大气科学及气象学]