2013年初夏湖北两次低涡暴雨对比分析

Comparative Analysis of Two Rainstorm Processes Caused by Low Vortex in Early Summer 2013 in Hubei

利用NCEP提供的高时空分辨率的GFS(Global Forecast System)0.5°×0.5°再分析资料和常规气象资料,对2013年初夏湖北两次低涡暴雨进行了对比分析。结果表明:(1)两次暴雨落区不同,5月暴雨由湖北西部向东北方向发展,主要位于湖北西部和中北部;而6月暴雨由湖北西南部向东发展,强降水主要位于湖北中部和东部。(2)两次暴雨落区不同是由于低涡移动的路径不同造成的,而低涡的移动路径受高低空配置的影响,不同的高低空配置导致这两次低涡暴雨的差异。(3)500 h Pa正的涡度平流使低涡移动发展,对低涡暴雨的发展和移动有很好的指导意义,而6月暴雨500 h Pa存在强正涡度平流中心,使低涡东移发展加强;另外,对流层低层温度平流对低涡的移动有引导作用。(4)边界层水汽辐合为低涡造成的强降水提供了充足的水汽条件。(5)中尺度云团对两次暴雨的影响机制不同,5月暴雨由于西部干区靠近,触发对流,使低涡西南部云团不断新生发展,在湖北中西部产生强降水;而6月暴雨由于东西向的云带向东北移动过程中,形成列车效应,在湖北中东部持续产生强降水。

Based on the automatic weather station data and the reanalysis data GFS( Global Forecast System) 0.5° ×0.5° with high spatial and temporal resolution from NCEP, two rainstorm processes occurred in 2013 were analyzed, which caused by low vortex. The result showed that:Firstly, the areas of the two heavy rains were different. The rain in May from west to the northeast direction, mainly located in western and north-central Hubei; And the heavy rain in June from the southwest to east, mainly located in the central and eastern Hubei. Secondly, the areas of these two heavy rains caused by different low vortex moving paths, and the low vortex moving paths depended on the configuration of the high and low allocation, which lead to the two differences of low vortex rainstorm. Thirdly, the positive vorticity advection at 500 h Pa make the low vortex develop and move, which had a good guide on vortex storm development. On June 6th to 7th, there was a strong positive vorticity advection center at 500 h Pa, which make the low vortex eastward development;besides, temperature advection in the lower troposphere had a guiding for the movement of the low vortex. Fourthly, water vapor convergence in boundary layer provided ample water vapor condition for the heavy rainfall. Finally, the mesoscale convective cloud clusters on the impact of the two rainfalls mechanism were different. The western arid region approaching the clouds triggered off convective activities, caused the cloud clusters in the southwest of the low vortex,which made the rain located in the Midwest Hubei in May; And the consistent heavy rainfall in the Mideast Hubei in June caused by' train effect',during the process of east-west cloud belt moving to north-east.