2016年1月22—26日云南寒潮天气过程分析

Analysis of a strong cold wave weather process in Yunnan during January 22-26, 2016

利用常规气象观测资料、物理量场和历史资料等对2016年1月22—26日发生在云南的一次低温雨雪天气过程进行了综合分析,并选取1983年12月强寒潮过程与之相对比,进一步了解寒潮天气过程的成因及预报重点,结果表明:500hPa上中高纬度的横槽转竖,强冷平流与南支槽前的暖湿气流相交汇,配合700hPa切变线及地面冷锋的推动,形成了此次自东北向西南的低温雨雪天气;通过对比可以看出,冬季寒潮天气过程的环流形势大致相似,但强度不同;降温幅度与冷空气强度正相关,而极端低温和雨雪天气的分布情况则还需要考虑前期温度的高低、前期的降水情况以及后期的天空状况;此外,发现700hPa的0℃线可以作为判断滇中及其以东地区降水形态转换的指标。

Based on conventional meteorological data,physical quantity field and historical climate data,a strong cold wave process with snowfall weather in Yunnan on January 22-26,2016 was analyzed comprehensively,which was then compared with a strong cold wave process that occurred in December 1983 to understand the causes of a strong cold wave process and predictors.The results show that the snow and rain weather is formed by two factors.Firstly,the 500 hPa horizontal trough in the middle-high latitude zone moves eastward and turns vertically.Secondly,the strong cold advection meets the warm air before the south branch trough,coordinated by the promotion of a shear line in 700 hPa and surface cold front.The results from the contrastive analysis shows that:strong cold wave processes have similar circulation type but different intensity;the range of temperature drop has a positive correlation with the intensity of cold air while the extreme low temperature and the distribution of the snow and rain weather are closely related to the temperature values and precipitation before the weather process and the changes of weather situation after the weather process.Moreover,the temperature line with 0 ℃ and 700 hPa can serve as an index to determine the changes of precipitation in central and eastern parts of Yunnan.