利用广州和深圳新一代多普勒天气雷达时间同步探测资料进行双多普勒雷达风场反演,分析了强热带风暴"风神"(0806)螺旋雨带的三维动力结构。螺旋雨带内部强回波区的低层有强辐合区,最大辐合超过-15×10-4 s-1;雨带的高层以辐散气流为主。雨带内部上升和下沉气流共存,最大上升气流为4 m/s,最大下沉气流超过-1 m/s。在沿着风暴中心的垂直剖面内,螺旋雨带外侧低层有较强的内流,气流从雨带外侧低层进入,最强内流位于1 km高度以下;雨带内侧有明显的外流。两支气流在雨带强回波区辐合,水汽在此处辐合抬升;这种动力结构对于强降水的维持具有重要作用。切向速度呈逆时针旋转,最大速度在3 km高度层,速度值随高度的增加逐渐减小。
The typhoon Fengshen(0806) landed in Kuiyong village,Shenzhen,Guangdong province,at 0530 BST 25 June 2008.It resulted in heavy rainfall in the province.The 3-D wind fields of a spiral rainband were retrieved from the data of dual Doppler radars.This spiral rainband was located to the west of the storm center and brought convective precipitation.Some strong reflectivity areas were shown to be at the low levels of the rainband region.Tilting outward from the inner edge to the outer edge of the rainband at the altitude of 2 km,a convergence zone with maximum value of-15×10-4 s-1 existed at these levels.There was a couple of mesoscale updraft and downdraft in the rainband.The maximum updraft is 4 m/s and that of the downdraft less than –1 m/s.The updraft zone was corresponding to a strong reflectivity zone.In the vertical cross section from the storm center,there was inflow in the outer side of the rainband.The strongest inflow existed below the 1-km level.The inflow entered the rainband at the low levels from outside the rainband.On the other hand,there was outflow in the inner side of it.These flows converged at the low levels of the central rainband.The tangential component of the wind decreased with height and the maximum wind region was at the 3-km level.