闽北一次初春强降水的成因分析

Causes Analysis of a Heavy Precipitation in Early Spring in the North of Fujian Province

利用常规观测资料、NCEP 1°×1°再分析资料、新一代天气雷达资料,对2012年3月6日-7日福建省北部地区暴雨成因进行诊断分析。结果表明:此次降水过程在高空西风槽南下带来的冷空气与西南暖湿气流交汇的背景下产生,暴雨区位于低空西南急流北侧、低层切变南侧、地面冷锋附近;强降水落区位于层结不稳定的湿区中,低层辐合、高层辐散有利于对流发展;干冷空气的侵入时高层高值位涡库向北向下伸展,促使中低层气旋涡度发展,从而导致强降水的发生;雷达回波分析表明,低层暖平流、高层冷平流、区域上空辐合形势都有利于对流性降水的产生。

Basing on the conventional observational data, NCEP l^xl ~reanalysis data, the new generation weather radar data, the rainstorm occurred in the north of Fujian province at March 6-7,2012 was analyzed. It shows that the precipitation process occurs in the intersection of the southwest warm air and the cold air accompanied the upper westerly trough moving south. Heavy rain area is located in the north side of the low-level southwest jet, the south side of low-level wind shear, near to the surface cold front. The strong precipitation area is located in the stratification instability of the wet zone, where the low-level convergence and upper-level divergence are con- ducive to the development of convection. With the dry cold air intrusion, the high-level high value potential vor- tex stretches northward and downward, causing the development of the low-level vortex. And the radar echo anal- ysis shows that the low-level warm advections, the high-level cold advection, and the convergence situation over the region are all conducive to the generation of convective precipitation.