Q矢量和湿位涡在梅雨期区域性暴雨中的诊断分析

Diagnosis analysis of regional rainstorm in Meiyu rain period using Q vector and moist potential vorticity

利用常规地面观测资料、区域自动站降水资料和NCEP再分析资料,根据Q矢量与湿位涡理论对2010年6月19—21日长江中下游暴雨过程进行诊断分析。结果表明:此次暴雨是由低层切变缓慢东移南压造成的;Q矢量绝对值大值区和Q矢量锋生函数大值区与强降水带相对应,值的变化也能反映出降水的增强与减弱,但Q矢量锋生函数中心与降水中心对应有时并不一致;Q矢量散度变化与雨带中心的加强减弱对应较好;强降水带处于MPV1正负值交界的等值线密集区,且其梯度的增大对应降水增强,梯度减小对应降水减弱。

Based on the conventional surface observation data, the precipitation data from automatic weather sta- tions and the NCEP reanalysis data, a rainstorm process on June 19-21,2010 in the middle and lower reaches of the Yangtze River was diagnosed by Q vector and moist potential vorticity theory. The results indicate that the lower level shear moves slowly southeastwards which causes the rainstorm. The region that has big absolute values of the Q vector and Q vector frontogenesis function is corresponding to the strong rain band and their values change with rainfall, while the big value center of Q vector frontogenesis function and the rainfall center are sometimes not con- sistent. The change of Q vector divergence coincides with that of rain band center. The strong rainfall band is situ- ated on the dense contour area with transition between positive and negative value of MPV1 and increasing gradient of MPVI is corresponding to rainfall enhancement, and vice versa.