东亚副热带西风急流活动与长江中下游梅雨异常关系的研究  

A Study of the Relationship between East Asia Subtropical Westerly Jet and Abnormal Meiyu in the Middle-Lower Reaches of the Yangtze River

作　　者：金荣花[1,2,3] 李维京[4] 张博 闫彩霞[5] 

机构地区：[1]中国气象科学研究院,北京100081 [2]南京信息工程大学,南京210044 [3]国家气象中心,北京100081 [4]国家气候中心,北京100081 [5]成都信息工程学院,成都610225

出　　处：《大气科学》2012年第4期722-732,共11页Chinese Journal of Atmospheric Sciences

基　　金：科技部国家科技支撑计划项目2009BAC51B03;公益性行业(气象)科研专项GYHY(QX)GYHY200906007;中国气象局气象新技术推广项目重点项目CMATG20092D02

摘　　要：本文利用1960～2009年NCEP/NCAR再分析日平均资料和中国714站20时(北京时)日降水量资料,分析了梅雨季节东亚副热带西风急流逐日演变特征与长江中下游异常丰梅和空梅的关系,研究了东亚副热带西风急流活动影响梅雨异常的机理,讨论了监测和分析东亚副热带西风急流对梅雨中期预报的意义。梅雨期合成分析显示,异常丰梅年较空梅年急流强度偏强,急流带狭窄,质量与动量集中。逐日演变特征表现为,丰(空)梅年急流围绕气候态位置经向平稳摆动(振荡幅度大),关键区(30oN～37.5oN,110oE～130oE)纬向风强度偏强(弱),东亚至西太平洋(80oE～160oE)上空急流最大中心主频次在125oE(145oE)附近,靠近(远离)我国东部地区并位于下风方。影响梅雨异常机理研究表明,异常丰梅年,200hPa我国东部地区上空急流轴线、散度零线和散度距平零线在37.5oN附近"重合",急流轴以北为辐合,以南为强辐散,辐散中心区与辐散距平中心区"重合"在长江中下游地区上空,高空强辐散流出,对应低层强辐合流入,配合从底层到高层深厚的强垂直上升运动,为梅雨提供了良好动力环境场;高低空急流耦合作用,有利于低空西南风加强,长江中下游以南地区为西南水汽通量距平,为持续性降水提供了良好的水汽输送条件;强高空副热带锋区配合典型陡直梅雨锋区,有利于高空急流质量和动量维持,也利于深对流发展。空梅年的情形则相反。从强度、位置及其变化等多方面综合监测和分析东亚副热带西风急流中期变化特征,可以更好地把握和认识急流对梅雨异常的影响及其机理,对于梅雨中期预报问题是有帮助的。By using the daily reanalysis data provided by National Centers for Environmental Prediction-National Center for Atmospheric Research （NCEP/NCAR） and daily precipitation data at 2000 BT （Beijing time） from 714 Chinese meteorological stations during period 1960-2009, the relationship between the East Asia subtropical westerly jet （EASWJ） and abnormal typical, atypical Meiyu in the middle-lower reaches of the Yangtze River is analyzed during the Meiyu season, the mechanism of the influences of EASWJ on Meiyu is studied, the significance of monitoring and analysis of the EASWJ to middle-range forecasting for Meiyu is discussed. The composite analysis during Meiyu seasons shows the EASWJ would be stronger, the jet band is narrow and the jet mass and momentum concentrate in the abnormally typical Meiyu year compared to those in the atypical Meiyu year. Daily evolution of the EASWJ is marked by following characters： In typical （atypical） Meiyu years, the jet swings steadily around its climatological position in meridional orientation （with large amplitude）; the zonal wind is stronger （weaker） in the key region of （30°N-37.5°N, 110°E-130°E）; the location of jet core is mainly around 125°E （145°E） from East Asia to the western Pacific, which is near to （away from） the east of China and locates on the leeward side. The study of influence mechanism on abnormal Meiyu shows that, in typical Meiyu years, 200-hPa axis line of the EASWJ, zero line of divergence, and zero line of divergence departure coincide at 37.5°N in the east of China, convergence is in the north of the jet axis and divergence is in the south of the jet axis, the region of divergence center coinciding with that of divergence departure center locates above the middle and lower reaches of the Yangtze River, the above items cooperating with strong divergence flowing out at upper levels, strong convergence at lower levels, and strong vertical ascending movement from lower to upper levels provide favorable dynamical c

关 键 词：东亚副热带西风急流 逐日演变 梅雨异常 影响机理 中期预报 

分 类 号：P461[天文地球—大气科学及气象学]