2009年6月皖南梅雨暴雨诊断分析和水汽后向轨迹模拟

利用常规天气图实况资料和NCEP每6 h 1次、2.5°×2.5°再分析资料及NOAA的GBL资料,对2009年6月28—30日安徽南部一次暴雨过程进行物理量诊断分析,同时使用HYSPLIT后向轨迹模式对水汽来源进行模拟。结果表明:高空辐散和低空辐合同时存在而导致的上升运动是此次暴雨的动力条件;来自孟加拉湾和南海充足的水汽来源是暴雨产生的前提条件;同时低空辐合产生切变诱发的不稳定能量释放,促使了大暴雨过程的产生。

Diagnostic analysis on Meiyu rainstorm and its simulation based on backward trajectory analysis method during June 2009 in the south of Anhui province

Based on the conventional observation data, the NCEP (2.5°×2.5°) reanalysis data and the GBL data from NOAA, a heavy rainstorm process on June 28-30, 2009 in the south of Anhui province was analyzed. Water vapor source was simulated by backward trajectory analysis method (Hysplit_4 dispersion model). The results indicate that divergence in upper level and convergence in lower level exist simultaneously, which leads to lifting motion. It becomes the dynamic conditions of this rainstorm. The adequate water vapor sources from the Bay of Bengal and the South China Sea are the premise conditions of forming rainstorm. At the same time, the convergence in lower level comes into being shear line, which makes the high instability energy released. These conditions accelerate the forming of rainstorm.