非常规资料在天津沿海一次灾害暴雨过程中的应用

Application of Unconventional Data in the Severe Rain Event in Tianjin Coastal Areas

利用风廓线雷达、微波辐射计、FY卫星亮温(TBB)及多普勒天气雷达探测等非常规资料,对2012年7月25日发生在天津沿海的一次特大暴雨过程进行分析和研究。结果表明:1)中尺度对流系统是造成暴雨的主要影响系统,地面中尺度辐合导致雷达回波列车效应从而产生区域性特大暴雨,强降水过程中50~55 dBZ强回波超过0℃层到达6.5 km高度,表现出高质心结构,雷达回波多仰角出现逆风区,持续时间近3 h,气旋式辐合增强,使对流有很强的组织性;2)暴雨过程伴随多个中尺度对流云团的强烈发展,成熟的对流云团冷中心温度达-63℃,云团后部温度等值线梯度大,对流旺盛,是引发强降水的关键;3)云液态水含量跃增与地面降水增强有直接关系,高液态水含量集中在0.8~1.6 km高度,强降水前湿层深厚,降水发生后湿层厚度迅速减小;4)风廓线雷达有能力捕捉到对暴雨预报有指示意义的信号,暴雨开始前约1~2 h边界层急流和低空急流建立,且低空急流在强降水发生前达到最强,暴雨开始前约1 h有中层弱冷空气侵入,暴雨开始前10~20 min急流可触发边界层扰动和低空扰动。

Based on the data from wind profiler radar,microwave radiometer,FY satellite brightness temperature and Doppler weather radar detection,the torrential rain event happened on July 25,2012 in Tianjin coastal areas is analyzed and studied.The results are as follows.1)Mesoscale convective system is the main impact system for the torrential rain,surface mesoscale convergence leads to the radar echo train effect and results in a regional heavy rainstorm.Radar echo is characterized by high centroid structure during heavy rainfall,50-55 dBZ strong echo extends upwards over 0℃to reach 6.5 km.The duration of the inversion area at multi elevation last nearly 3 hours and cyclonic convergence enhancement.There is a strong organization of convection.2)The torrential rain is accompanied by the strong development of multiple mesoscale convective clouds,the cold center of the mature convective cloud mass reaches-63℃,the gradient of the contour of the rear of the cloud mass is large,exuberant convection is the key to strong precipitation.3)The liquid water content in the cloud at the lower atmosphere is directly related the precipitation on the ground,the high liquid water concentrating upon 0.8-1.6 km,wet layer is deep before strong precipitation on the ground and the thickness of the wet layer decreases rapidly after precipitation.4)The wind profiler radar has the ability to capture the indicative features of the rainstorm forecast.The establishment of boundary layer jet and low level jet appears 1-2 h ahead of the rainstorm.And the low level jet reaches the strongest before the rainstorm.The middle layer of weak cold air intrusion occurs 1 h ahead of the rainstorm,the jet can trigger boundary layer disturbance and low altitude disturbance 10-20 min ahead of the rainstorm.