2008年广东“龙舟水”特点及诊断分析

文章对2008年5月28日至6月18日,广东省出现持续时间长、范围大、强度高的大暴雨降水过程进行分析。分析结果表明,形成这次＂龙舟水＂过程的原因如下：在欧亚中高纬度维持两槽一脊稳定的大环流形势,为暴雨的持续提供了冷空气,副高较弱位置偏东、偏南,暴雨持续期副高略有加强,使华南沿海地区暖湿气流加强;南支槽活跃,每次强降水过程均与西风槽、高空急流和低层切变线的南压过程配合;水汽源于孟加拉湾和南海且以孟加拉湾为主,水汽的辐合主要发生在华南沿海;华南沿海辐合上升为持续性＂龙舟水＂的产生提供了稳定的上升运动背景且主要出现在层结不稳定的条件下。

The Characteristics and Diagnostic Analysis of Guangdong Dragon-boat Rain in 2008

The article analyzes the long,wide-range,heavy rain precipitation which lasted in Guangdong Province from 28th of March to 18th of June in 2008.The results shows that the reason why the＂Dragon-boat Rain＂formed is as follows：the large circulation in Eurasia middle and high attitudes which kept the stability of the two troughs and one ridge provided cold air for the lasting of the heavy rain;by east and south in the weak position of the subtropical high,the heavy rain kept sub-high with a little strengthening,which reinforced the wet warm air in South China;southern trough was active and coordinated with the westerly trough,high-level jet flow and south-pressing process of low-level shear line in every heavy precipitation; the vapor came from Bay of Bengal（mainly）and South China Sea,and the convergence of vapor mainly occurred in south coast;the ascension of the convergence in south coast provided a steady ascension background for continuous dragon -boat rain and it mainly appeared unstable stratification.