厦门市2010年10月3日短时强降水成因分析

An analysis of the causes of short-time Severe Rainstorm in Xiamen in October 3rd 2010

2010年10月3日下午厦门地区出现了短时强降水天气，时雨量最高达54．8毫米。在秋季且中低层为偏北气流控制下，发生的短时强降水过程是十分罕见的。短时强降水是短时和短期预报的难点。本文利用常规资料、多普勒雷达资料、物理量诊断以及自动站资料等对本次强降水天气的成因进行分析，结果表明：厦门处于高空急流出口的左侧，有利于高层辐散的“抽吸作用”。500hPa高空槽东移，引导地面冷空气南下。700hPa显著降温区覆盖我省，与前期低层在副高控制下增温增湿的配合，增加了该区域的层结不稳定。广东西部到海南岛有热带低压活动。850hPa以下低层华南沿海维持一支较强的偏东气流，为暴雨的主要水汽通道。有两个重要的中尺度系统，一是低层存在干线，而干线附近是强对流天气最容易发生的地区，二是易激发强对流活动的地面辐合线。

a short-time severe rainstorm occurred in Xiamen area on October 3rd afternoon, which the maximum rainfall amount reach 54.8mm per hour. The weather process was uncommon in the condition of middle and low level northerlies in autumn. The severe rainstorm forecasting was very difficult in whether short-range or short-time weather forecasting. The routine data, Doppler data, diagnostic physical quantity and the automatic station data were used to analysis the cause of the precipitation process. The results showed： the Xiamen area was in the left side of the outlet of the upper level jet stream, which made for the pumping of the high-level divergence. The eastward shifting of upper level trough on 500hPa leaded the surface cold air down to the south. The notably temperature falling area in Fujian province on 700hPa, the warming and the humidification influenced by the subtropical anticyclone intensified the atmospheric instability. The water vapor channel of the heavy rain was set up by the activity of tropical depression in western Guangdong to Hainan province and the strong easterly airstream in south china costal region under 850hPa level. There were two mesoscale systems, one was the dry line in the low level, the other was the surface convergence line, where the severe convective weather both happened most easily.