Establishment of a multiple-Doppler radar wind retrieval system and its application to the analysis of mesoscale convective systems

A multiple-Doppler radar wind retrieval system is established by using a three dimensional variation method. The system consists of two parts. One is to interpolate reflectivities and radial velocities of nine Doppler radars of the Korea Meteorological Administration (KMA) into one analysis domain. The other is to retrieve three dimensional winds by minimizing a cost function that includes the following costs and constraints: the observed radial velocity cost, background wind cost, continuity constraint and smoothness constraint. In order to verify the performance of the system, retrieved winds are compared with observed winds obtained from five wind profilers of KMA. The performance of the system depends on the relative position to the baselines between Doppler radars. However, the performance of the system is enhanced when the number of overlaps among the radial velocities increases. The system is applied to the analysis of the evolution of a mesoscale convective system (MCS) on the Changma front on 1 July 2005. The analysis result shows that a new convective cell is developed by the convergence of the low troposphere winds at the organizing stage. The analysis of the vertical vorticity reveals that, among the two vorticity generation terms to be calculated utilizing the retrieved winds, tilting or twisting source dominates the divergence source in most convective regions. The strong downdrafts associated with the storm are produced on the downdraft branch of a meridional direction secondary circulation across the Changma front.