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

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.