南半球环流异常与我国夏季旱涝分布关系及其影响机制  

The Relationship and Influence Mechanism Between Circulation Anomaly in Southern Hemisphere and Summer Precipitation Distribution in China

作　　者：何敏[1] 孙林海[1] 艾秀 

机构地区：[1]国家气候中心中国气象局气候研究开放实验室,北京100081

出　　处：《应用气象学报》2006年第4期394-402,共9页Journal of Applied Meteorological Science

摘　　要：利用1951—2000年NCEP/NCAR风场和高度场再分析资料及全国160站降水量资料,采用奇异值分解、相关和合成分析方法,研究6—8月南半球500 hPa高度、高低层纬向风距平差异常(Δu850-Δu200)与我国夏季旱涝分布的关系及其影响机制。结果表明:当500 hPa澳大利亚高压脊偏强及西南太平洋热带地区高低层纬向风距平差为负值时,来自南半球冷空气活动偏弱,有利于西北太平洋副热带高压位置偏南,热带季风偏弱,我国夏季雨带偏南。反之,当澳大利亚高压脊偏弱及西南太平洋热带地区高低层纬向风距平差为正值时,我国北方降水偏多。同时,定义了澳大利亚冬季风指数,指出澳大利亚冬季风强年和弱年影响我国夏季旱涝分布异常的水汽输送型式不同。To introduce signal on southern hemisphere circulation anomaly for diagnose and forecast of precipitation trend during flood season, the relationship between southern hemisphere circulation anomalies and its influence mechanism on summer precipitation distribution patterns in China is studied using SVD （Singular Value Decom- position）, correlation and analogue methods. Also, the 500 hPa height field and zonal wind shear anomaly from high-level to low-level troposphere （A u 850 - A u 200） in southern hemisphere, and summer precipitation distribu- tion patterns in China are analyzed. Results show that： （!） When the ridge of Australian high is stronger and zonal wind shear anomaly in the southwest Pacific tropical region is negative, the cold air that comes from the southern hemisphere is weaker. It should be beneficial to the stronger subtropical monsoon and weaker tropical monsoon. And the northwest Pacific subtropical ridge shifts southward, and summer precipitation over the Yangtze River and south of the Yangtze River should be above normal. The rainbelt is located in southern China. On the other hand, when the ridge of Australian high is weaker, the zonal wind shear in southwest Pacific tropical region is positive anomaly, more precipitation appears in northern China. ① The possible mechanism for the influence of circulation anomaly in southern hemisphere on the summer precipitation distribution patterns in China is as follows： there is a close relationship between the anomaly of circulation and cold air activity in southern hemisphere and the monsoon circulation system activity in East Asia. It may also influence positions of the Northwest Pacific subtropical ridge and the rainbelt in China. ② Furthermore, Australian winter monsoon index is defined. It indicates the circulation anomaly and the intensity of cold air activity in southern hemisphere troposphere. When Australia winter monsoon index is negative, precipitation is richer over the Yangtze River and the north part in the south of

关 键 词：南半球环流 夏季降水 奇异值分解 

分 类 号：P434[天文地球—大气科学及气象学] P426.616