一次强对流暴雨天气的环境条件及中尺度对流云团分析

利用常规观测资料、NCEP/NCAR再分析资料及逐时FY-2E红外卫星云图、自动站和本地WRF等资料,对2010年8月10日夜间宁夏东部强对流暴雨天气过程的大尺度环流背景、影响系统、环境条件、垂直风切变及中尺度特征进行综合分析。结果表明:此次过程是在有利的大尺度环流背景和环境条件下,伴随副高北抬、低空急流发展,在高原槽、低涡切变、地面冷锋和地面辐合线的共同作用下,激发中尺度天气系统在宁夏东部产生的;随着暴雨时段临近,暴雨区上空低空急流和垂直风切变增强,湿层加厚,中低层空气趋于饱和,近地面层持续东风,低层湿层上部维持逆温层,对流不稳定能量急剧释放;强对流暴雨出现在中尺度暴雨云团发展阶段的后期和成熟阶段的早期,在地面气旋式环流右前方、地面辐合线北侧、对流云团发展的前端、冷云中心略偏后的位置上;暴雨站点上空TBB和降水位相变化有一致性,降水峰值对应TBB峰值。

Environmental conditions and mesoscale convective cloud during a severe convective rainstorm process

The large scale circulation,influence system,environmental conditions,vertical wind shear and mesoscale characteristics during a severe convective storm process occurred in the east of Ningxia at night were analyzed by using the conventional observation data,NCEP/NCAR reanalyzed data,hourly FY-2E infrared cloud images,automatic weather station data and local mesoscale numerical weather prediction model WRF.The results showed the rainstorm event occurred under beneficial large scale circulation background and environmental conditions.During the rainstorm process,west pacific subtropical high moved toward north-west,low altitude jet developed,the combined action of plateau trough,low vortex with shear,ground cold front and ground convergence line excited mesoscale weather systems and then caused convective rainstorm in the east of Ningxia;Along with the approaching of rainstorm,low altitude jet and vertical wind shear developed,wet layer thickened,air in the middle and low altitude level was tending to saturated,east wind persisted at surface layer,inversion layer maintained over low level wet layer,convective unstable energy released rapidly;Severe convective rainstorm occurred at the end of developing stage and beginning of mature stage of mesoscale convective cloud,at the right-front of surface cyclonic circulation,the north side of ground convergence line,the front of mesoscale convective cloud and back of cold cloud center;At the weather stations where rainstorm occurred,the variation of TBB and precipitation was consistent,the peak value of precipitation was corresponding with the peak value of TBB.