陕西北部一次局地雷暴天气中尺度分析

Mesoscale Analysis of a Storm Weather in Northern Shaanxi

利用常规气象观测资料、多普勒雷达、FY-2D卫星云图,分析了2015年4月20日延安富县出现的一次局地冰雹天气过程。结果表明,综合高空850、700和500 h Pa的主要特征,850 h Pa自南向北侵入河套的湿舌,配合西侧风切变对应500 h Pa干冷空气,这种配合有利于河套上空不稳定层结的建立。而700 h Pa西北侧与东侧方向冷空气的不断侵入,有利于河套地区低层暖湿空气的抬升。陕北地区低层的湿区和大气不稳定层结状态的维持,地面低压发展以及辐合线的存在有利于低层暖湿空气的抬升。边界层辐合线、干线等中尺度抬升系统提供了对流风暴发生所需的能量和触发机制,为对流发生的中尺度环境分析提供依据。

Using conventional meteorological observation data,Doppler radar,FY-2D satellite cloud image,a storm weather process appeared in Fu County,Yanan City on Apr. 20,2015 was analyzed. By considering main characteristics of upper air 850,700,500 h Pa,850 h Pa cold air intrusion from south to north with west side wind shear and 500 h Pa cold air are conducive to the establishment of Hetao instability stratification over the sky. Constant intrusion of cold air from 700 h Pa northwest side and east side direction is conducive to the low layer of warm air rising in Hetao Area. Northern Shaanxi area low layer of wet zone and atmospheric instability stratification state maintenance and ground pressure development and convergence line is in favor of the uplift of the low layer warm and humid air. The boundary layer convergence line,trunk line provided the energy and trigger mechanism for the convective storm,also provided the basis for the analysis of mesoscale environment.