一次西南涡特大暴雨过程中MCS的演变特征

摘要

采用常规观测、地面自动观测、风廓线雷达及多普勒雷达资料,结合NCEP/NCAR 1°×1°再分析资料对2013年6月30日川渝特大暴雨过程中MCS的演变特征进行了分析,结果表明:①强降水及MCS均呈现增强—减弱再次增强的演变特征,在MCS的增强阶段有中气旋和强降水超级单体的活动.②MCS生成并维持于西南涡前部次级环流的上升支内,西南涡缓慢东移并持续增强,为MCS的长时间维持提供了有利的背景动力条件.③MCS的波动性演变特征与西南涡的持续增强特征并不一致,其波动性演变与中低层西南风或南风急流的变化、低空及地面暖湿入流的变化有关.中低层西南风或南风急流的增强、低空及地面暖湿入流的增强均有利于MCS的增强.%An analysis is made of the evolution characteristics of a MCS during a torrential rain in Sichuan and Chongqing,using the conventional observation,automatic ground station,wind profiler,Doppler radar,and NCEP/NCAR 1°× 1° reanalysis data.The results show that:(1) The torrential rainfall and MCS exhibited the evolution features of enhancing-reducing-enhancing again during the rain.Heavy precipitation supercells and mesoscale-γ cyclones appeared in the MCS enhancement phase.(2) The MCS was generated and maintained inside the ascending branch of the secondary circulation in front of Southwest Vortex,which moved eastward slowly and enhanced continuously and provided favorable background dynamic conditions for the long-term maintenance of the MCS.(3) The fluctuating evolution characteristics of the MCS are not consistent with the persistent enhancement characteristics of Southwest Vortex.The fluctuating evolution of the MCS was related to the changes of Southwest Jet or South Jet in the low and middle levels and the warm-wet inflows in the low level and on the ground.The enhancement of the Southwest Jet or South Jet in the lower and middle levels and the enhancement of the warm-wet inflows in the low-level and on the ground all provided favorable conditions for the enhancement of MCS.