2008年广东史上最强龙舟水的分析研究

The Analysis of the Strongest Dragon-boat Rain in GuangDong province in 2008

利用气象常规观测资料及NCEP/NCAR再分析资料,对形成2008年广东"龙舟水"期间4次强降雨的天气系统、强降水形成的物理机制以及中低纬度天气系统之间的相互作用和影响进行分析和诊断。结果表明,强降水过程大多发生在500 hPa西风槽活跃及850hPa低涡东移的环流背景下,西风槽与东移的低空低涡结合是暴雨产生的重要天气系统;印度洋越赤道气流、南海南部越赤道气流比常年偏强,使偏南季风异常活跃,其以2条路径输送水汽,为广东"龙舟水"期间强降水提供了充沛的水汽条件;副热带高压偏弱,偏东,有利于高空低压槽影响华南,带来大气运动的不稳定和引导冷空气的南下。

Using conventional observation data and NCEP/NCAR reanalysis data, physical mechanism affecting weather system and rain-formation, interaction and inter-impact between low and middle latitude weather system of four times heavyrain in Guangdong ＂Dragon-boat rain＂ peri- od of 2008 were analyzed and diagnosed. The results showed that several strong rain procedures mostly occurred in the background of 500 hPa westly trough actively and the 850 hPa low-eddy moving eastward. The combination of the low-level vorbex which shift eastward and the westerly trough is the major weather slfsterm which produced heavy rain. It was discovered that the Indian cross-equatorial flow, the South China Sea cross-equatorial flow was stronger, which made further south monsoon extremely active ,and the vapor was transported by two paths, which provid- ed the plentiful vapor condition for ＂Dragon-boat rain＂ period in Guangdong;The Subtropical High was weaker and leaning east which was conducive to high-altitude trough of low pressure over the South China, brought instability of atmospheric motion and guided southward of cold air.