汉江流域2021年伏秋连汛降水季内差异特征及成因分析  

Analysis on the characteristics and causes of intraseasonal differences of the continuous rainfall in Hanjiang River Basin during the summer and autumn in 2021

作　　者：肖莺[1,2,3,4] 高雅琦 杜良敏 任永建[2,5] XIAO Ying;GAO Yaqi;DU Liangmin;REN Yongjian(Wuhan Regional Climate Center,Wuhan 430074,China;Key Laboratory of Tobacco Meteorology Research,Wuhan 430205,China;Three Gorges National Climatological Observatory,Yichang 443002,Hubei,China;Key laboratory of Basin Heavy Rainfall,CMA,Wuhan 430205,China;Hubei Meteorological Service Center,Wuhan 430205,China)

机构地区：[1]武汉区域气候中心,湖北武汉430074 [2]湖北省烟草气象研究重点实验室,湖北武汉430205 [3]三峡国家气候观象台,湖北宜昌443002 [4]中国气象局流域强降水重点开放实验室,湖北武汉430205 [5]湖北省气象服务中心,湖北武汉430205

出　　处：《干旱气象》2024年第4期563-575,共13页Journal of Arid Meteorology

基　　金：中国气象局创新发展专项(CXFZ2024J002);湖北省烟草公司科技项目(027Y2022-006);长江流域气象开放基金项目(CJLY2022Y07);湖北省自然科学基金项目(2023AFD097、2022CFD014);中国长江三峡电力股份有限公司项目(2423020048);湖北省气象局基金项目(2023Y06)共同资助。

摘　　要：汉江流域是中国重要的调水水源区,研究其降水特征对防涝抗旱具有重要意义。基于汉江流域62个国家气象站降水资料及美国国家环境预报中心/国家大气研究中心(National Center for Envi⁃ronmental Prediction/National Center for Atmospheric Research,NCEP/NCAR)再分析资料,通过百分位数、相关分析和T-N波作用通量,探讨了2021年伏秋(8—10月)连汛期间汉江降水的季内差异特征及其与大气环流和海温的关系。结果表明:2021年伏秋期间,汉江上游流域出现破纪录降水,极端性强、总量大。降水在伏夏和秋季两个时段均偏多,但秋季的多雨区位置更偏北。伏夏期间,北大西洋经西伯利亚向东频散的Rossby波使得欧亚上空维持“两槽两脊”,冷空气较强,同时西太平洋副热带高压(简称“副高”)强势西伸,通过西南和偏东两支通道向北输送暖湿水汽;冷暖空气在高空急流南侧对峙并辐合上升,导致降水异常偏多。秋季,北太平洋频散的Rossby波使得欧亚上空维持“两槽一脊”,冷空气较弱;副高断裂导致水汽通道偏南,高空急流北抬使冷暖空气辐合上升位置偏北,造成雨区偏北。2021年汉江流域伏夏降水异常受热带东大西洋海温正异常影响,秋季受赤道中太平洋冷海温影响。Hanjiang River Basin is an important water source area in China,and studying its precipitation characteristics is of great sig⁃nificance for flood prevention and drought resistance.Based on the daily precipitation data of 62 stations in the Hanjiang River and NCEP/NCAR reanalysis data,the intraseasonal variation characteristics of the precipitation over the Hanjiang River from August to Oc⁃tober in 2021 and its relationship with atmospheric circulation and sea surface temperature were studied by using percentile,correla⁃tion methods and T-N wave activity flux.The results show that the record-breaking precipitation in the Hanjiang River during this pe⁃riod occurred in the upper reaches of the basin,characterized by extreme intensity and large total precipitation.Precipitation was above normal in both the summer and autumn periods,but the rainy regions in autumn were positioned further to the north.In summer,the en⁃ergy of Rossby waves dispersing eastward from the North Atlantic through Siberia maintained a“two-troughs-two-ridges”pattern over Eurasia,bringing strong cold air.Affected by the strengthening and westward extension of the subtropical high in the western Pacific,moist water vapors were transported to the north through the southwest and eastward water vapor channels.The old and warm air con⁃fronted and converged on the south side of the upper-level jet stream,resulting in abnormally high precipitation.In autumn,the energy from Rossby waves dispersing from the North Pacific maintained a“two-troughs-one-ridge”circulation pattern over Eurasia,with rela⁃tively weaker cold air.The breaking of the subtropical high in the western Pacific led to southern water vapor channel.The northward movement of the high-altitude jet stream caused the convergence of cold and warm air to rise northward,resulting in the northward movement of above-average precipitation.The abnormal precipitation during summer in 2021 in the Hanjiang River Basin was influ⁃enced by the positive anomalies in sea surface tem

关 键 词：伏秋连汛 季内差异 T-N波作用通量 热带海温 

分 类 号：P467[天文地球—大气科学及气象学]