鲁西北持续性暴雨非地转湿Q矢量分析

Ageostrophic wet Q-vector analysis of a persistent torrential rainfall event in the northwest of Shandong Province

利用常规观测资料、NECP/NCAR提供的1°×1°FNL全球再分析资料,对2012年鲁西北一次持续性暴雨进行了湿Q矢量方法诊断分析。结果表明:此次持续暴雨出现在有利的环流背景下,降水区域集中并有明显的中尺度特征,湿Q矢量方法是分析强降水落区很好的工具;925~850 h Pa湿Q矢量散度与强降水落区有较好的对应关系,但暴雨并不总是出现在湿Q矢量散度负值区中心,有时出现在湿Q矢量散度梯度大的负值区一侧;700 h Pa湿Q矢量涡度正值中心与散度负值重叠的区域是中尺度低值系统发展有利的区域,与未来6~12 h暴雨落区有很好的对应;湿Q矢量锋生函数差值预报强降水落区明显优于锋生函数。

Based on conventional observation data and 1°×1°FNL global reanalysis data from NECP/NCAR, the wet Q -vector method is applied to diagnose a persistent torrential rainfall event in the northwest of Shandong Province in 2012. The results are as follows. The torrential rainfall event appears under favorable circulations and the precipitation area is concentrated and has obvious mesoscale features. The wet Q -vector method serves as a powerful tool to analyze heavy precipitation area. The wet Q -vector divergence field is correlated well to heavy precipitation area from 925 hPa to 850 hPa, while the torrential rain does not always appear in the negative center of wet Q -vector divergence. It sometimes appears in the negative area of wet Q -vector divergence with high gradient. The superposition area of the the positive center of wet Q -vector vorticity and the negative center of divergence at 700 hPa is advantageous for developing mesoscale system of low value, which corresponds well to the torrential rainfall area in the next 6 to 12 hours. The function of frontogenesis difference using the wet Q -vector is superior to the function of frontogenesis in forecasting where the torrential rain will take place.