呼和浩特市连续两日短时强降水天气对比分析

Comparative Analysis on Continuous Two-Day Short Time Strong Precipitation in Huhhot

利用常规观测和非常规监测资料从环流背景及发生条件等方面对比分析了2012年7月25-26日呼和浩特市连续两日出现的短时强降水天气。结果表明:(1)两次降水过程都是在东高西低的环境场产生,西太平洋副热带高压与贝加尔湖低涡稳定维持,使冷暖空气长时间交汇;(2)两次降水过程都是由中低纬系统、上下游系统、高低层系统以及多种尺度系统共同作用及配置产生的,中小尺度天气系统是引起两次降水过程的主要原因,但主要影响系统位置及产生因子的特征又有所不同;(3)前一次降水过程整层湿度条件好,且整层均在暖区,对流相对较弱;后一次存在明显上干冷下暖湿的对流不稳定层结结构,对流相对较强;(4)两次降水过程都是层状云和对流云混合降水,但前一次降水过程层状云水平及垂直尺度相对较大,后一次主要是对流云降水;(5)反射率因子、垂直累积液态水含量及对流高度分析降水过程,前一次降水过程都比后一次弱,前一次存在明显的低空急流,反射率因子范围广、呈片状、东北移动并向南扩,后一次反射率因子范围小、呈带状、东移南扩且明显存在列车效应;(6)受地形辐合抬升作用,两次降水过程都发生在呼和浩特市中部及大青山南侧、蛮汉山西侧。

Short time strong precipitation that appears in Huhhot in continuous two days from 25 to 26 July 2012 was analyzed from circulation background and happening condition and etc by using conventional observation data and non-conventional materials. The results showthat:( 1) These two processes occur in the circulation of‘high east and lowwest'. West Pacific subtropical high and Baikal loware stable maintained,which is favorable for the cold and warm air meets for a long time.( 2) The joint action and configuration of the middle-lowlatitude weather system,the up-down stream system,high-lowlevel and multi-scale system have contribute to this event,among these the meso-small scale system is the main reason of strong precipitation,but the location of main influence system and characteristics of producing factors are different.( 3) The whole level humidity condition is better and located in warm region,but convection is relatively weak in the first day; in a while in the second day,convective instability stratification structure appears because of atmospheric stratification of dry and cold in the up and warm and humid in the low,so the convection is comparably strong.( 4) These two days' strong precipitation is both the stratiform clouds and convective clouds induced comprehensive precipitation,but the horizontal and vertical scale of first event is larger; in a while convective precipitation happens mainly in the second.( 5) From radar data,the reflectivity factor,vertical integrated liquid water content and echo top of the first day are weaker than the second day; there exists a lowlevel jet seen from radical velocity chart; strong reflectivity area appears wide and flake shape can be seen from reflectivity factor,moves toward northeast and expand southward in the first day; while appears narrowrange and band shape,moves eastward and expands southward,appears a obvious train effect in the second day.( 6) These two days precipitation occurs in the central of Huhhot region which located in the south of Daqing mountain and in the west of Manhan Mountain,so the topography induced updraft motion plays critical role in the process.