NOTES AND An Observational Study of the Extremely Heavy Rain Event in Northern Vietnam during 30 October–1 November 2008
NOTES AND An Observational Study of the Extremely Heavy Rain Event in Northern Vietnam during 30 October–1 November 2008
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发表时间：
2011
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通讯作者：
P. Wu;Y. Fukutomi
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作者：
P. Wu;Y. Fukutomi
2008年10月30日至11月1日，越南北方发生特大暴雨。连续三天的特大暴雨导致越南首都河内及其周边地区发生了24年来最严重的一次渗血事件。日本气象厅气候数据同化系统（JCDAS）再分析数据的分析结果显示，南海上空形成了一股天气尺度的热带波扰动，并在印度支那半岛东部沿海向西北方向移动，给越南带来了特大暴雨。北方。在中纬度地区，地面高压带从蒙古西部向东南延伸到东海，导致其东南边缘沿着中国南部沿海出现持续的东北季风流。东北风切变与热带扰动共同作用，在越南北方产生了较强的低空风辐合。对热带扰动结构的分析表明，扰动的纬向风结构和气旋性涡度垂直延伸到300 hPa左右，最大扰动出现在800-600 hPa层，并随高度呈近似垂直分布。大气的一个显著特征是对流层上层的等效位温在500 hPa以上有很大的增加，在300-150 hPa层中有大于15 m s（cid：1）1的强南风。热带扰动与持续的亚洲冬季风共同作用，导致了这次极端降水事件。
An extraordinarily heavy rain event occurred in northern Vietnam from 30 October to 1 November 2008. The three consecutive days of extremely heavy rain resulted in the worst flooding event in Hanoi, the capital of Vietnam, and its environs in 24 years. Results from analysis of the Japan Meteorological Agency Climate Data Assimilation System (JCDAS) re-analysis data show that a synoptic-scale tropical wave disturbance formed over the South China Sea and traveled northwestward over the eastern coast of the Indochinese Peninsula, brought the extremely heavy rainfall to northern Vietnam. In the mid-latitudes, a belt of surface high extended southeastward from western Mongolia to the East China Sea, causing a persistent northeasterly monsoonal flow on its southeastern edge along the southern coast of China. The northeasterly flow worked together with the tropical disturbance, creating a strong low-level wind convergence in northern Vietnam. Examination of the structure of the tropical disturbance revealed that the meridional wind structure and cyclonic vorticity of the disturbance extended vertically to approximately 300 hPa, with the maximum fluctuations occurring at the 800–600 hPa layer and shows nearly vertical with height. A remarkable feature of the atmosphere is the large increases in the equivalent potential temperature in the upper troposphere higher than about 500 hPa, with strong southerly winds greater than 15 m s (cid:1) 1 in the 300–150 hPa layers for the three days in question. In conclusion, the tropical disturbance, which worked together with the persistent Asian winter monsoon, caused the extreme rainfall event.