单多普勒天气雷达反演降水粒子垂直速度Ⅱ：实例分析

The precipitation particles’ vertical velocity retrieval with single Doppler weather radar. Part Ⅱ： Case analysis

中文关键词:  单多普勒天气雷达  改进的体积速度处理（VVP）方法  垂直速度  强对流  “桑美”台风

英文关键词:Single Doppler weather radar  Modified VVP method  Vertical velocity  Severe convection  Typhoon Saomai (2006)

中文摘要:

      垂直速度的反演一直是多普勒雷达风场反演的关键问题和难点，在对单多普勒雷达体积速度处理（VVP）法反演垂直速度进行敏感性分析和改进求解方程的基础上，对其反演三维风场和适用的风速条件做了模拟检验，并在强对流天气和台风实例中反演与验证。分析结果表明，改进的反演算法对径向风速的误差并不敏感，在高低仰角上的精度相同，观测误差越小或风速越大时，反演精度越高。对广州一次强对流过程的反演结果表明，改进的反演算法可以反演出对流单体中降水粒子垂直运动的变化。在中尺度气旋中，粒子垂直速度大值区的分布与气旋外围风切变的位置相符；在气旋的消散阶段下落速度增大，因而可通过粒子的垂直速度变化判断雨强的变化。对2006年超强台风“桑美”的反演结果显示，能够反演出台风中心的下沉气流以及外围交替出现的上升与下沉气流，在台风中心处下沉速度的大值区位于7—8 km高度，低层与高层的值相对较小。反演效果表明，改进后的反演方法较准确地反映了降水粒子的垂直运动，使多普勒雷达资料可揭示更多的三维风场细节，有助于改进强对流天气过程的风场结构分析和降雨落区的预测。

英文摘要:

      A key problem in the 3-dimensional wind retrieval by using Doppler radar radial velocity is the vertical velocity retrieval, in this paper the Modified Volume Velocity Processing (MVVP) method on which the vertical wind velocity retrieval is based is analyzed and the solving equations are improved. The MVVP method is examined by using the simulative data to determine the appropriate velocity range, and it is applied in the severe convection and the typhoon cases. The results show that MVVP method is not sensitive to random errors in the radial velocity. The accuracy of retrieval is the same at the different elevations. Furthermore, the performance of retrieval is good in the cases with small random error or the large wind velocity. The retrieval results of a severe convection occurred at the Guangzhou station demonstrate that the vertical velocity of precipitation particles in a convective cell can be exactly obtained by the MVVP method. It indicates that the fall velocity increases during the dissipation process of the mesoscale cyclone and the distribution of precipitation particles tends to fast fall, which is consisted with the wind shear around the mesoscale cycle. Thus the change of rain can be estimated according to the fall velocity of precipitation particles. For Typhoon Saomai (2006), the downdraft in the typhoon eye and the updraft-downdraft alternatively in the eye-wall can be retrieved. In the eye area, the strongest downdraft is located at the height of 7-8 km. In the contrary, vertical velocities are smaller at the upper and lower levels. The performance of the MVVP method shows that the vertical movement of particles can be retrieved exactly, which is helpful to reveal the details of severe weather, and to improve the precipitation location forecast.