黔东南地形影响局地突发性暴雨的中尺度天气分析与数值试验

Mesoscale Synoptic Meteorology Analysis and Numerical Experiment of Local Sudden Rainstorm Affected by Topography in Southeast Part of Guizhou Province

基于FY-2E TBB资料、ERA5再分析资料和WRF v3.9.1.1模式对2015年5月27日贵州省雷山县一次突发性暴雨过程进行中尺度天气学分析和数值试验。结果表明:(1)低空西南急流、切变线与地面辐合线是本次山地突发性暴雨的直接影响系统。(2)TBB低值区与突发性暴雨落区有明显的对应关系,TBB值的减小对应着降水的增强,反之对应降水的减弱。(3)ERA5再分析资料作为初始场对于突发性暴雨的模拟效果优于FNL分析资料和ERA-Interim再分析资料。(4)地形通过改变山地动力、水汽等物理量场从而影响暴雨的落区和强度。地形的抬升作用造成水汽与不稳定能量在迎风坡堆积,使层结不稳定性增强,在强烈的上升运动作用下触发对流不稳定发展。(5)雷公山地形对于降水有显著的增幅作用,山脉高度升高后,雨带扩大,雨量增加;反之雨带西移,雨量减小。

Based on FY-2E TBB data,ERA5 reanalysis data and WRF v3.9.1.1 model,mesoscale synoptic meteorology analysis and numerical simulation are carried on for the sudden rainstorm in Leishan county on 27 May 2015.The results indicate that:(1)Southwest low-level jet,shear line and surface convergence line are the direct effect systems of this terrain sudden rainstorm.(2)There is an obvious correspondence between the low value area of TBB and the sudden rainstorm area,the decrease of TBB value indicates the increase of precipitation,otherwise it indicates the decrease of precipitation.(3)The simulation effect of ERA5 reanalysis data that is as the initial field for sudden rainstorm is better than that of FNL analysis data and ERA-Interim reanalysis data.(4)The area and intensity of rainstorm are influenced by the terrain through modulating the dynamic and water vapor field of mountain.The water vapor and unstable energy is accumulated on the windward slope through the uplifting effect of the terrain,which enhances the instability of the stratification and triggers the unstable development of convection under the action of strong ascending motion.(5)The topography of Mountain Leigong has a significant effect on sudden rainstorm:With the increasing of terrain height,rain belt expanded and rainfall increased;On the contrary,the rain belt moves west-ward and the rainfall decreases.