淮河流域大暴雨特征分析

利用实时观测资料和网格间距2.5°×2.5°、间隔6 h的NCEP/NCAR再分析资料,对2005年7月淮河流域大暴雨发生的大尺度背景、环境场条件以及触发和维持机制及天气动力学诊断分析.结果表明:高低空急流的优势配置,耦合形势的建立以及高空急流右侧的强辐散场的存在为暴雨的发生提供了有利的环境条件;暴雨区中上升运动和水汽辐合均大于周围区域,中低层为对流不稳定层结;暴雨区位于湿位涡和湿相对位涡负值中心附近偏暖湿气流一侧,对暴雨落区预报有一定的指示意义.

Characteristic Analysis of Heavy Rainstorm in Huaihe Basein

The large-scale background,environment field,triggering and maintaining mechanism and weather dynamics of heavy rainstorm in Huaihe Basein on July,2005 were diagnosed with the observation data and NCEP/NCAR 6 h reanalysis data with resolution 2.5°×2.5°.The results showed that erectness of coupling pattern between upper-layer jet and low jet and a divergence area, which came forth in right of upper-layer jet provide favorable surrounding conditions.The most intensive moisture convergence,the strongest ascending movement and the most instable convection stratification all occurred in the rainfall center.The rainstorm occurred at the warm and wet side of the negative value center of the moist potential vorticity (MPV) and relative MPV,which had certain indicative significance for the forecast of rainstorm areas.