Abstract:

Based on the conventional observation data，Doppler radar data and automatic meteorological station data，a squall line case
occurred in the north of Shaanxi on May 16，2009 was analyzed． The result show that an unstable stratification with warm and humid air
at the low level and cold and dry air at the upper level was a favorable condition for the storm，and the cold downdraft at the rearward
of the storm was obvious． The storm had a structure of double convergence center on the divergence field，which could intensify the surface
depression and the vertical updraft． The squall line had obvious meso － scale characteristics with meso － scale convergence line at
low level identified from Doppler radial velocity chart，and the squall line was well correlation with dewpoint front，meso － scale depression
and convergence line of wind field．

Key words: squall line, meso － scale, radar radial velocity

摘要：

使用常规探测资料、多普勒雷达资料以及自动观测站资料，对2009 年5 月16 日陕西北部一次飑线过程进行分析，发现有利的环境条件是低层暖湿，高层干冷的不稳定层结，后方冷下沉气流表现明显; 散度场具有双辐合结构，并且中层辐散强于低层辐合，从而促进地面低值系统发展，进一步加强垂直上升运动。飑线过程中尺度特征明显，雷达径向速度图上可以识别出中低空的中尺度辐合线，同时地面上与露点锋、中低压以及风场辐合线等中尺度系统关系密切。

关键词: 飑线, 中尺度, 雷达径向速度