卫星资料在一次极端短时强降水过程中的释用分析

Analysis and Explanation of Satellite Data during an Extreme Short-time Heavy Rainfall

利用FY2卫星云图及TBB资料、地面加密自动站资料及常规气象观测资料,详细分析了2016年7月24日天津沿岸极端短时强降水发生时的对流云团特征及TBB变化,结果表明:①500 hPa"北低南高"的环流形势稳定维持,垂直方向两段近乎垂直的低涡柱,副高加强西伸北抬,地面低压倒槽北顶,低空急流风速辐合,高空强烈辐散,利于上升运动的加强和维持,造成了此次极端短时强降水天气过程。②红外云图中,河北中部的对流云团A沿副高外围引导气流东移,并入天津中南部对流云团B,加强为对流云团C,700~925 hPa低空急流风速辐合,同时地面冷空气入侵,对C云团的发展起到促进作用,极端短时强降水发生在对流云团合并加强之后。水汽云图上云团边界非常明显,副高西北侧的大量水汽在低空急流及辐合气流的作用下,有一个明显变亮的过程。可见光云图上,白亮密实的中尺度对流云团不断发展、壮大。③TBB低值带与极端短时强降水发生的区域相对应,强降水落区位于TBB低值区内,即云团强烈发展的中心位置,此位置云团向上强烈发展,对流旺盛,对短时强降水的发生较为有利。强降水发生在对流发展最旺盛期后的能量释放过程中,相对TBB值最大变率在演变趋势上有一定的滞后性,强降水主要发生在TBB变率最大值之后。

Based on FY2 satellite cloud images and TBB data,intensified automatic surface observation data and conventional meteorological observation data,the characteristics of convective cloud cluster and TBB change in Tianjin coastal area on 24 July,2016 are analyzed in detail.The results show:(1)The stable circulation of lower in north and higher in south at 500 hPa,the two near vertically vortex column in the vertical direction,the subtropical high strengthening westward and extending northward,low pressure with an inverted trough lifting north,convergence of low-level jet wind speed and strong divergence in high altitude are beneficial to the strengthening and maintenance of the ascending motion,which causes the extreme short time heavy precipitation.(2)On infrared cloud image,the convective cloud cluster A in center Hebei moves eastward along steering flow of the subtropical high,merging into the cloud cluster B in central and southern Tianjin,strengthing to the convective cloud cluster C.The convergence of low-level jet wind speed at 700 to 925 hPa and the intrusion of cold air on the ground promote the development of cloud cluster C,extreme short-time strong rainfall occurs after convective cloud cluster with strengthening.The cloud boundary is very obvious on the water vapor map,and a large number of water vapor on the northwest side of the subtropical high has a significant brightening process under the action of the low level jet and the convergence airflow.On visible cloud image,white light and dense mesoscale convective cloud cluster develops and grows constantly.(3)With low TBB corresponding to the extreme short-time strong rainfall area,strong precipitation area is located in the low TBB value area,where the center position of the strong development of cloud cluster.The strong development of cloud indicates strong convection,which is favorable to the occurrence of short time heavy rainfall.Heavy rainfall occurs in the energy release process after the most vigorous development stage.The maximum TBB variability has a lagging trend in the evolution trend.Heavy rainfall mainly occurs after the maximum TBB variability.