“海高斯”减弱环流引发的大暴雨天气诊断分析

Diagnostic Analysis on the Heavy Rainstorm Weather Induced by "Higos" Weakened Circulation

2008年10月6日,福建省中南部沿海地区出现大范围强降水。利用常规气象资料和NCEP1°×1°6 h一次的分析资料进行诊断分析,以探讨此次大暴雨发生和维持的原因。结果表明,此次大暴雨天气过程主要是"海高斯"减弱后残留的低压系统在由500 hPa西风槽引导带来的低层弱冷空气的激发下形成的,低压东南侧的低空西南急流和西北侧的偏北风气流共同作用,使低压环流得到加强和维持。计算得出存在着有利于出现强降水的物理量场配置。风暴相对螺旋度分析表明,螺旋度分布和时间演变同强降水及其时间演变具有较好的对应关系,螺旋度的强度变化对于暴雨的演变有一定的指示意义。

The large range of heavy precipitation occurred in the central-southern coast of Fujian on October 6,2008.By using the conventional meteorological data and NCEP 1°×1° 6 h one time analysis data,we discussed the appearance and maintenance reasons of this heavy rainstorm.The results showed that this heavy rainstorm weather process was mainly formed by the low-pressure system which was remained after ＂Higos＂ weakened.The low-pressure system was stimulated by the weak cold air in the low layer which was brought by 500 hPa westerly trough.The low-altitude southwest jet stream in the southeast of low pressure co-acted with the northerly air current in the northwest.It made that the low-pressure circulation strengthened and kept.The calculation gained that the physical quantity field configuration was favorable for the appearance of the heavy precipitation.The analysis on the relative helicity of storm showed that the distribution and the time evolution of helicity had the good corresponding relationship with the distribution and the time evolution of heavy precipitation.The intensity change of helicity had the certain instruction significance on the evolution of rainstorm.