一次大暴雨雷达回波特征及数值模拟

利用NCEP再分析资料和天津多普勒雷达等资料,对2008年7月14—15日发生在河北唐山及天津一带的暴雨过程进行了分析,并通过MM5数值模拟阐述了雷达资料分析的正确性。结果表明:此次大暴雨发生在中低纬天气系统相互作用的背景下,700hPa高空槽、850hPa低涡及地面中尺度辐合线是引发此次暴雨主要影响系统;低空急流是暴雨主要的水汽来源;低空辐合高层辐散、锋面抬升是暴雨系统发展的动力机制;对流层中部冷空气活动引起的西南低空急流脉动与暴雨的增幅有密切关系;涡旋状和带状回波是主要降水回波。

Radar Features and Simulation Analysis of a Heavy Rainfall Event

Based on the NCEP 1°×1°reanalysis data and Tianjin Doppler data, the causes of the heavy rainfall happened in Tangshan and Tianjin between 14 and 15 July 2008 is analyzed, and the simulation with the PSU/NCAR MM5 model is made to verify the precision of the analysis. The results show that the heavy rainfall event occurred under the background of the interaction of mid- and low-latitude systems, caused by the upper trough on 700 hPa, low vortex on 850 hPa, and mesoscale convergence line in the boundary-layer. The vapor was delivered mainly by the low jet. The low-level convergence, upper-level divergence, and lifting motion near the front were dynamical mechanisms that make the low vortex developed. The pulsatory strengthening of the southwest jet stream caused by the cold air from the mid- 4 level was related to the amplifying of heavy rainfall. The major precipitation echoes of the heavy rainfall were eddy and band echoes.