大气科学学报2017，Vol.40Issue(3)：299-309,11.DOI:10.13878/j.cnki.dqkxxb.20160323001
东亚夏季风指数的分类及物理特征分析
Classification of East Asian summer monsoon indicesand their basic physical features
摘要
Abstract
Dozens of East Asian summer monsoon (EASM) indices have been proposed to represent the main features of anomalous summer monsoon activity based on different physical consideration.In this study,sixteen representa tive EASM indices were calculated based on the NCEP/NCAR reanalysis data (1961-2010) and detailed comparison has been performed to detect the differences among the EASM indices.We also explored the basic physical features of various EASM indices by comparing their differences in the related anomalous patterns of atmospheric general circulation and summer rainfall.The possible linkages of EASM indices with the predominant modes of EASM were also discussed.It is found that sixteen EASM indices can be generally classified into two categories (Category Ⅰ and Category Ⅱ).Category Ⅰ mainly exhibits the decadal variation of EASM while Category Ⅱ is featured by strong interannual variability of EASM.Further analysis shows that:1) Category Ⅰ mainly reflects a consistent spatial variation of EASM and is closely linked to the first leading mode of EASM acquired by the extended empirical orthogonal function (EEOF) analysis of 850 hPa wind.Positive (negative) index of category shows intensified (weakened) southerly in the whole East Asian area,which is accompanied with anomalously intensified cyclonic (anti-cyclonic) circulation around the Lake Baikal and slightly northward (southward)western Pacific subtropical high (WPSH).There are also corresponding anomalous 500 hPa geopotential height fields exhibiting a "+-+" ("-+-") anomalous zonal pattern in the mid-high latitudes,originating from the western Europe,across the West Siberia plain,and extending to northeast Asia.Meanwhile,there is significantly increased (reduced) rainfall in North and Northeast China but reduced (increased) rainfall in the Yangtze River and its southern area,which consists of a typical dipole of monsoon rainfall anomalies.Category Ⅰ shows better description of summer precipitation anomalies in North and Northeast China.2)Category Ⅱ of EASMI generally represents an out-of-phase variation of the summer wind between southern and northern China.Positive (negative) index corresponds to weaker (stronger)summer monsoon in southeast China but stronger (weaker) summer monsoon in northeast China,which is accompanied with anomalously intensified cyclonic (anti-cyclonic) circulation over the Northwest Pacific and northward (southward) shifting of WPSH.Correspondingly,500 hPa geopotential height anomalies exhibit a "-+ -"("+-+") meridional tripole pattern in East China,from the western North Pacific (WNP),across Japan to the Okhotsk Sea,which is similar to the typical East Asia-Pacific (EAP) teleconnection pattern.The summer precipi tation decreases (increases) in the middle and lower reaches of the Yangtze River,while it increases (decreases)over the east of Northeast China and the southeast coast of China.Category Ⅱ shows better description of summer precipitation over the Yangtze River basin.关键词
东亚夏季风指数/空间多模态/大气环流异常/夏季降水/分类讨论Key words
East Asian summer monsoonindex/multi-spatial modes/atmospheric general circulation anomaly/summer precipitation/classification引用本文复制引用
陈海山,陈健康..东亚夏季风指数的分类及物理特征分析[J].大气科学学报,2017,40(3):299-309,11.基金项目
公益性行业(气象)科研专项(GYHY201206017) （气象）
国家自然科学基金资助项目(41230422) （41230422）
江苏省自然科学基金杰出青年基金项目(BK20130047) （BK20130047）
“新世纪优秀人才支持计划” （）
