受墨西哥湾流影响的“大气河”对欧洲西岸冬季极端降水的次季节-季节预报技巧的影响  

The Impact of Atmospheric Rivers Influenced by the Gulf Stream on Sub-Seasonal-to-Seasonal Forecast Skill of Extreme Rainfall on Western Europe in Winter

作　　者：吴一非 贾英来 韩子清 冀蕊 张杰 谢晓敏 Wu Yifei;Jia Yinglai;Han Ziqing;Ji Rui;Zhang Jie;Xie Xiaomin(Quanzhou Meteorological Bureau,Quanzhou 362000,China;College of Oceanic and Atmospheric Sciences,Ocean University of China,Qingdao 266100,China)

机构地区：[1]泉州市气象局,福建泉州362000 [2]中国海洋大学海洋与大气学院,山东青岛266100

出　　处：《中国海洋大学学报（自然科学版）》2023年第4期135-144,共10页Periodical of Ocean University of China

基　　金：国家自然科学基金项目(41975065);泰山学者攀登计划项目资助。

摘　　要：在冬季,欧洲西岸的强降水多由大气河(Atmospheric river,AR)而引起,而大气河又受到墨西哥湾流(Gulf stream,GS)区域海洋锋面变化的调制作用,因此GS区域海洋锋面的低频变化可能对欧洲西岸强降水在次季节-季节(Sub-seasonal to seasonal,S2S)时间尺度上的预报技巧存在影响。本文基于欧洲气象中心发布的S2S预报数据集,结合ERA5的再分析数据,考察了GS区域海表面温度(Sea surface temperature,SST)、AR及欧洲西岸强降水的S2S预报效果,发现相较其他区域而言,在GS锋面处SST的预报值偏高,预报技巧偏低,受此影响,海洋锋面处海面风速预报值偏大,从而增强洋面蒸发,导致向大气输送更多的热量和水汽,促进更多AR的发生。受AR发生频率预报结果的影响,西欧沿岸南部(北部)AR发生频率预报值偏高(偏低),从而导致南部(北部)预报的强降水增多(减少),AR引起的降水占总降水的比值也增加(减少)。In winter,the extreme rainfall on Western Europe is largely impacted by atmospheric rivers(AR),which is known to be modulated by the Gulf Stream(GS) ocean front.Therefore,the low-frequency changes of the GS front may have influences on the forecast skill of extreme rainfall on Western Europe on the sub-seasonal to seasonal(S2S) time scale.Based on the hindcast output from the European Centre for Medium-Range Weather Forecasts(ECMWF) model in S2S datasets,along with OISST and ERA5 as observation data,we examined the S2S forecast skill of the sea surface temperature(SST),AR occurrence frequency and extreme rainfall in north Atlantic and Western Europe region.It is found that compared with other regions,the forecast SST along the GS front is much higher than observations.Influenced by the highly biased SST forecast results,the wind velocity along the GS front is also forecasted higher,leading to increased heat flux and water vapor from ocean to atmosphere.This heating and moistening in S2S forecast results generate more ARs neat the GS region and then influenced Western Europe upon land falling process of ARs.Thus the higher bias of SST along the GS front results in increased(decreased) extreme rain in southern(northern) coast of Western Europe,which increased(decreased) AR occurrence frequency in the south(north).The AR-related precipitation is also increased(decreased) relative to total precipitation in the north and south Western Europe.

关 键 词：湾流延伸体区域 海洋锋 强降水 大气河 欧洲西岸 

分 类 号：P47[天文地球—大气科学及气象学]