Comparion Analysis on the Mesoscale Characteristics of Two Rainstorm Processes Caused by the Central Asian Vortex in the West of South Xinjiang

Based on the hourly precipitation from automatic stations,conventional observation data,TBB from FY-2D,NCEP reanalysis data,objective analysis fields from ECMWF with 0.25°× 0.25° and T639 with 0.28°× 0.28°spatial resoluition in the west of South Xinjiang,two rainstorm processes occurring on 21 to 23 May 2012 and 26 to 29 May 2013 in the west of South Xinjiang were comparatively analyzed by using statistics and filtering method.The results show that two rainstorm processes occurred under the influence of Central Asian vortex,and rainstaorm centers of them were same,but the ranges,duration and intensity were obviously different,which may be caused by the different mesoscale system.Two rainstorm processes were separately generated by meso-β system and meso-α system,and the measure of mesoscale system influencing was smaller,so the rainfall intensity was bigger and the duration was shorter,and vice versa.the uplifting and convergence in middle and low level,which were affected by the terrain,played an important role to rainstorm in the west of South Xinjiang.The surface convergence line was main meso-scale system of rainstorm in the west of South Xinjiang,and it triggered two heavy rains.The cold air got over the Pamir plateau into the basin,and met with the warm and wet air,which formed the strong convergence line,and it was in favor of convective precipitation.