2009年湖北入梅首场暴雨的垂直螺旋度分析

Vertical Helicity Analysis on the First Rainstorm of the Rainy Season in Hubei in 2009

利用湖北省自动雨量站资料和NCEP1°×1°全球再分析资料,对湖北省2009年6月28～30日发生的暴雨天气过程进行垂直螺旋度分析。结果表明,整层强的垂直上升运动稳定维持情况下,垂直螺旋度时空演变特征能很好地反映强降水出现时段及其落区范围的大小;间隔6h的700hPa垂直螺旋度梯度大值区和∑θse(500+700+850)水平能量锋区叠加区的的分布对6h强降水的落区有很好的指示意义;大降水中心出现的区域有低层正与高层负垂直螺旋度的配置,在低层正垂直螺旋度略高于高层负值时,更有利于大暴雨中心产生。

The heavy rainfall event occured over Hubei Province from 28 to 30 June 2009 was studied with the NCEP 1.0x1.0 FNL operational global analysis data and automatic rainfall station data by means of vertical helicity analysis. The results indicated that there exists close relationship between vertical helicity and strong precipitation period and heavy rainfall area. The combination of the gradient large value areas of vertical helicity at 700 hPa level and the energy frontal zone of ∑θse（500＋700＋850） would provide with good indicative significance for the 6 hours heavy rainfall areas. The heavy precipitation was generated where exists the positive vertical helicity center at low-level and negative vertical helicity center at high-level,vertical in the lower level slightly higher than the negative helicity,the center is more conducive to produce heavy rain.