1614号超强台风“莫兰蒂”在浙江沿海降水预报偏小的原因

通过对1614号超强台风“莫兰蒂”在浙江沿海降水预报偏小的原因进行回顾，同时基于美国NOAA HYSPLIT4模式，对“莫兰蒂”水汽来源进行轨迹聚类，针对不同路径来源的水汽在“莫兰蒂”浙江沿海降水中的贡献差异进行定量分析，结果表明:数值模式对“莫兰蒂”路径预报偏西、降水预报偏小，直接影响了主观预报服务中降水强度和落区的判断，而数值产品对中纬度环流作用和浙江沿海台风倒槽的预报出现偏差，同时对1616号台风“马勒卡”路径预报偏东，导致主观预报忽略了“莫兰蒂”与其他天气系统的相互作用，影响了对降水动力和水汽因子的判断，也是降水预报偏小的原因之一。“莫兰蒂”水汽输送有3支气流，分别来自东北、东南和偏南洋(海)面，后2支气流为主要水汽来源，浙北沿海以东南向水汽输送最重要，对水汽和降水贡献高达70%以上，表现出1616号台风“马勒卡”对“莫兰蒂”在浙北沿海降水的重要作用，而浙南沿海台风本体的偏南气流与“马勒卡”的东南气流的水汽输送作用相当。可见台风降水预报中，需要密切关注台风环流与其它天气系统以及双台风间的相互作用。 

REASONS FOR RAINFALL UNDERESTIMATION OF THE SUPER TYPHOON 1614 (MERANTI) AT COASTAL ZHEJIANG PROVINCE

Review was carried out in this paper to investigate the reasons for underestimated rainfall of the super typhoon Meranti (1614) in coastal Zhejiang province, and water vapor trajectory clustering was done as well by using the NOAA HYSPLIT4 model to investigate the quantitative contributions of water vapor to rainfalls from different channels. Results show that typhoon track deviations and rainfall underestimations by numerical models had direct impacts on the subjective forecasts of rainfall intensities and hitting areas. Moreover, numerical model forecast deviations, including weather patterns at mid-latitude, a typhoon reverse trough at coastal Zhejiang areas, and the eastward track offset of typhoon Malakas (1616), which led to the neglect of the interactions between Meranti and other weather systems in subject forecast and impacted the correct forecasts of rainfall dynamics and vapor conditions, should all be blamed for the rainfall underestimations. There were three water vapor trajectories for Meranti, from the northeast, southeast and south oceans (seas) respectively, with the latter two being the main sources. The southeast airflow was the most important for the rainfalls at the northern coast of Zhejiang, which took up more than 70% of the contributions to water vapors and rainfalls, implying the important role of typhoon Malakas for the rainfalls of typhoon Meranti. While at the southern coast of the province, the south airflow took almost as much role as the southeast airflow in water vapor transportation. Analysis implied that in routine services attentions should be paid to the interactions between typhoons and other weather systems as well as binary typhoon interactions.