中亚低涡造成新疆北部区域暴雨成因分析

Analysis on Rainstorm Caused by Central Asian Vortex in Northern Xinjiang

利用区域自动站、常规观测、EC细网格、卫星云图TBB及FNL资料,对新疆北部2013年6月20—21日区域性暴雨天气成因进行分析,并与前期南疆暴雨进行对比。结果表明,中亚低涡是该过程主要影响系统,暴雨由对流层中低层及地面中尺度系统直接造成,云图及自动站风场均监测到γ中尺度系统。受阿尔泰山脉西北段高东南段低及沙尔巴斯套北高南低的地形作用,中尺度低涡及850 hPa沿山前西北上的气旋性涡旋在暴雨区旋转、滞留、增强,使散度低层辐合、高层辐散结构与垂直上升运动在同一时次达最强,助推暴雨增幅。此次暴雨过程与南疆发生的暴雨存在一些差异。

Using conventional observation data, automatic weather station data, the high resolution model of ECMWF data, and FY-2E TBB data, 1 km and FNL data, the reason for regional rainstorm in Northern Xinjiang in 20--21 June 2013 was analyzed and compared with the early analysis of rainstorm that had hap- pened in Southern Xinjiang. The results showed that the Central Asian vortex was the main influencing system. The rainstorm was directly caused by in the middle and lower troposphere and the ground meso scale system. Meso-7 convection system was monitored by both the cloud image and the automatic station wind field. Affected by the terrain of the Altai Mountains and Sharbasitao, the mesoscale low vortex and the cyclonic vortex along the piedmont from the southeast to the northwest at 850 hPa rotated, stranded and enhanced, making the divergence structure of low-level convergence and high-level divergence formed and the strongest vertical upward movement at the same time enhanced rainstorm to increase. This heavy rain process was different from the heavy rain in Southern Xinjiang.