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气象:2020,46(1):15-28
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集合预报对台风天鹅(2015)远距离暴雨的不确定性研究
何斌,楼茂园,李海军,范晓红,陆琛莉,潘士雄
(嘉兴市气象局,嘉兴 314050; 上海台风研究所,上海 200030; 浙江省气象学会,杭州 310008)
Research on Uncertainty of Ensemble Forecasts of the Far Distance Torrential Rainfall by Typhoon Goni (2015)
HE Bin,LOU Maoyuan,LI Haijun,FAN Xiaohong,LU Chenli,PAN Shixiong
(Jiaxing Meteorological Office of Zhejiang Province, Jiaxing 314050; Shanghai Typhoon Institute, CMA, Shanghai 200030; Zhejiang Meteorological Society, Hangzhou 310008)
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投稿时间:2018-08-22    修订日期:2019-04-10
中文摘要: 2015年8月23—24日期间台风天鹅引发华东中部沿海地区出现暴雨或大暴雨天气。基于欧洲中期天气预报中心的集合预报分析导致此次远距离暴雨预报不确定的关键原因,并利用集合敏感性分析方法研究影响此次暴雨过程的主要天气系统的敏感区域,此外对暴雨发生发展的热动力机制展开探讨,主要结论包括:集合预报对此次台风天鹅引起的远距离暴雨的可预报性明显偏低,仅在暴雨发生前24 h才做出较大调整。在不同起报时次下,当台风路径的系统性偏差最小时,台风降水集合预报也最接近实况,但是进一步的分析表明,台风路径误差与降水量级之间的对应关系并不确定。不同雨量成员组间中低层环流场的对比分析表明:高空槽的预报差异是集合预报不确定的主要原因,高空槽东移加深有利于增加暴雨区的斜压不稳定,也有利于增强对流层低层的水汽输送急流带。500 hPa高度场的敏感性分析表明无论是初始场还是预报场,暴雨区平均降雨量均与高空槽的东移和加深显著相关,且随着预报时次的临近,显著相关区域向低槽下游明显扩大。此外还发现高空槽的东移有利于增强(减弱)暴雨区左(右)侧低层冷空气的强度,使得台风右侧更多暖湿气流向暴雨区输送。
Abstract:A torrential rainfall caused by Typhoon Goni during 23-24 August 2015 influenced some coastal areas in East China. This paper utilizes the ECMWF ensemble forecasts to study the key reason for the forecast uncertainty of the far distance torrential rainfall and uses the ensemble sensitivity method to investigate the sensitivity areas of the primary weather system. Meanwhile, the thermodynamic formation mechanisms of the torrential rainfall are also discussed. It is indicated that the predictability of ensemble forecasts of the typhoon-induced far distance torrential rainfall was obviously low and the significant forecast adjustment occurred just 24 hours before the torrential rainfall. At initial time when the systematic track error was minimum, the ensemble precipitation forecast was mostly close to the observation. But further analysis shows that the correlation between the deviation of typhoon track and the precipitation level is uncertainty. The contrastive analysis of the mid- and lower-circulations between two ensemble groups at different precipitation levels indicates that the forecast difference of the upper trough is the main cause for the forecast uncertainty. The eastward movement and intensification of the upper trough not only increased the baroclinic instability in the torrential rainfall area, but also enhanced the circulation magnitude in the side of the typhoon facing the area. The sensitivity analysis on 500 hPa geopotential height shows that, whether on the initial field or on the forecast fields, the mean precipitation in the torrential rainfall area has notable correlation with the movement and intensification of the upper trough. With the increasing forecast time, the areas with significant correlation expand downstream of the upper trough. In addition it is found that the movement of the upper trough can enhance (reduce) the intensification of the cold air on the left (right) side of the torrential rainfall area and make more moisture air on the right side of the typhoon transported to the torrential rainfall area.
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基金项目:浙江省自然科学基金项目(LY19D050001)和中国气象局预报员专项(CMAYBY2017-030)共同资助
引用文本:
何斌,楼茂园,李海军,范晓红,陆琛莉,潘士雄,2020.集合预报对台风天鹅(2015)远距离暴雨的不确定性研究[J].气象,46(1):15-28.
HE Bin,LOU Maoyuan,LI Haijun,FAN Xiaohong,LU Chenli,PAN Shixiong,2020.Research on Uncertainty of Ensemble Forecasts of the Far Distance Torrential Rainfall by Typhoon Goni (2015)[J].Meteor Mon,46(1):15-28.