多普勒雷达风场反演技术在西南涡暴雨过程中的应用

摘要

提利用多普勒天气雷达四维变分同化方法反演了2010和2013年重庆市两次西南涡内的局地强降水不同高度水平风场，分析了易发生局地强降水区域的局地环流特征。结果表明：风场反演能较准确地给出低空急流、低层辐合和局地气旋性涡旋的位置及演变情况，辐合线演变及低空急流的强度和移向对强降水有指示意义；局地气旋性涡旋越深厚，局地强降水的强度和范围越大；不同高度的气旋性涡旋耦合，可能有利于急流的加强和水汽输送。%Horizontal wind fields in different heights were retrieved for two local severe rainfall processes within the southwest vortexes which occurred in Chongqing in 2010 and 2013,respectively,using Doppler weather radar 4DVar (four-dimensional variation)assimilation technique.Local circulation patterns which are prone to local intense rainfalls are also analyzed.The results show that the position and evolution of low-level jet streams,low-level convergence lines and local cyclonic vortices can be accurately denoted by retrieved wind fields.The evolution of convergence lines and the intensity and transfer of low-level jet streams are indicative of heavy precipitation.The deeper the local cyclonic vortex is,the greater the inten-sity and extension of local intense rainfall become.Coupling in cyclonic vortexes of different heights can be prone to intensification of low-level jet stream and transportation of moisture.