非常规探测资料在天津沿海3次灾害暴雨过程中的差异性分析

Difference Analysis of Three Rainstorm Events by Non-conventional Observation Data in Tianjin Coastal Areas

综合利用常规观测资料,高时空分辨率的地面自动站资料、多普勒天气雷达、风廓线仪等多种非常规观测资料以及NCEP再分析资料,对2012年7月21日、7月26日和7月30日至8月1日天津沿海地区3次暴雨过程的影响系统及差异特征进行了对比分析,得到以下结论:①3次过程属于3种暴雨天气形势,7.21为低槽冷锋型暴雨,7.26为副高边缘型暴雨,7.30属于暖切变线型暴雨。②雷达反射率因子特征方面,7.21过程呈现带状-“人”字型-线状回波3个演变阶段,具有低质心高效率的结构特征;7.26过程单体移动具有明显的“列车效应”,且具有高质心、回波悬垂和有界弱回波区的结构特征;7.31过程为典型的层状云降水回波。径向速度方面,7.21和7.26过程分别呈现单涡式和双涡管式的气旋旋转结构。③风廓线特征方面,7.21过程近地面层东风急流对短时强降水的指示意义更明显,双切变线是7.21过程区别于一般降水过程的另一特征;7.26过程具有双层急流结构及扰动由近地面层-边界层-对流层低层的传播特征;7.31过程除短暂出现的边界层偏东急流之外,并无低空急流出现。

The conventional observation data,high spatial-temporal resolution non-conventional data such as auto-weather station(AWS),Doppler radar and wind profiler,NCEP reanalysis data were used to comparatively analyze three torrential rain events occurred in Tianjin on 21 July(7.21),26 July(7.26)and 31 July(7.31)of 2012.The results show that:Firstly,the three events were classified into three weather situations:7.21 was lower-level trough and surface cold front type;7.26 was subtropical high edge type while 7.31 was warm shear line type.Secondly,the 7.21 process radar echo had the characteristics of“band”shape,“herringbone”shape,“linear”shape and low centroid which was similar to tropical heavy rainfall;Besides the train effect and high centroid could be obviously seen in the radar echo imagery during 7.26 torrential rain,the echo overhang and bounded weak echo area could also be observed;The 7.31 was characterized in stratiform precipitation echo.Moreover,in terms of radial velocity,there was a single vortex in 7.21,and a double-vortex flow pattern in 7.26.Finally,the signatures of vertical airflows in wind profile were different:the boundary layer east jet has clearly implications in 7.21 and doubled low-level jets could be observation in 7.26,but there was no low-level jet in 7.31 except transient boundary layer east jet.The double shear line was a unique feature of 7.21 event.