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黄燕玲, 陈海山, 蒋薇, 许蓓, 李忠贤. 东亚夏季风异常活动的多模态特征:不同再分析资料的比较分析[J]. 大气科学, 2015, 39(1): 145-160. DOI: 10.3878/j.issn.1006-9895.1404.13326
引用本文: 黄燕玲, 陈海山, 蒋薇, 许蓓, 李忠贤. 东亚夏季风异常活动的多模态特征:不同再分析资料的比较分析[J]. 大气科学, 2015, 39(1): 145-160. DOI: 10.3878/j.issn.1006-9895.1404.13326
HUANG Yanling, CHEN Haishan, JIANG Wei, XU Bei, LI Zhongxian. Multi-spatial Modes of East Asian Summer Monsoon Activity: Comparative Analysis of Various Reanalysis Data[J]. Chinese Journal of Atmospheric Sciences, 2015, 39(1): 145-160. DOI: 10.3878/j.issn.1006-9895.1404.13326
Citation: HUANG Yanling, CHEN Haishan, JIANG Wei, XU Bei, LI Zhongxian. Multi-spatial Modes of East Asian Summer Monsoon Activity: Comparative Analysis of Various Reanalysis Data[J]. Chinese Journal of Atmospheric Sciences, 2015, 39(1): 145-160. DOI: 10.3878/j.issn.1006-9895.1404.13326

东亚夏季风异常活动的多模态特征:不同再分析资料的比较分析

Multi-spatial Modes of East Asian Summer Monsoon Activity: Comparative Analysis of Various Reanalysis Data

  • 摘要: 利用1979~2002年ERA-40、ERA interim、JRA-25和NCEP-DOE AMIP-Ⅱ(简称为NCEP-2)再分析资料,采用扩展经验正交分解(EEOF)、相关分析等方法,对比分析了不同资料所揭示的东亚夏季风异常活动的多模态特征,在此基础上探讨了东亚夏季风异常活动各模态对应的大气环流异常分布型及其与中国夏季降水的可能联系。结果表明:(1)四套再分析资料所揭示的东亚夏季风异常活动均存在三种差异显著的空间模态,且各套资料对东亚夏季风异常活动空间多模态特征具有很好的一致性,仅NCEP-2的结果与其他资料略有差异。(2)第一模态体现了夏季风年际异常在中国南方和北方的反相变化,并具有显著的3~6年和准8年周期;与正(负)时间系数相对应,850 hPa风场、500 hPa高度场、SLP均显示东亚沿岸存在从西北太平洋经过日本以南到达鄂霍次克海的“-+-”(“+-+”)经向三极型结构;相应的降水变化在长江中下游为显著的负(正)异常,而在我国东北东部、东南沿海及云南西部则为正(负)异常。(3)第二模态反映了夏季风活动主导模态的一致性变化且在1993年左右发生年代际转折,并呈现准12年周期的强弱交替分布。当对应的时间系数为正(负)时,850 hPa风场在环贝加尔湖地区受强大的异常反气旋(气旋)控制;500 hPa高度场上,中高纬地区表现为异常的纬向波列结构,具体表现为起源于欧洲大陆西部经西西伯利亚平原向东南方向延伸至东北亚地区的“+-+”(“-+-”)的波列;SLP在我国大陆主要为正(负)异常,东亚夏季风整体减弱(加强);对应的夏季降水异常场呈现“南涝北旱”(“南旱北涝”)的分布形势。(4)第三模态表明了夏季风异常活动的东西反相变化,且有12~16年的准周期变化。对应正(负)的时间系数,115°E 以东地区盛行异常偏南(北)风,而115°E 以西地区主要盛行异常偏北(南)风;500 hPa高度场、SLP均显示出东亚沿岸地区、鄂霍次克海至日本以南洋面的“-+”(“+-”)波列以及欧亚大陆北部的准纬向遥相关波列;夏季降水在我国大部分地区偏多(偏少),显著变化主要位于黄淮及附近地区。

     

    Abstract: Based on ERA-40, ERA interim, JRA-25, and NCEP-DOE AMIP-Ⅱ (NCEP-2) reanalysis data (1979-2002), we compare the basic features of the multi-spatial modes, which reflect the anomalous activity of the East Asian Summer Monsoon (EASM). The relevant atmospheric general circulation anomalies, as well as their association with the summer rainfall in China, are further explored by using statistical methods including correlation and extended empirical orthogonal function (EEOF) analysis. Results suggest that: (1) the EASM exhibits three typical spatial modes with significant differences, which are independent of the dataset sources, with the exception of NCEP-2 in which slightly different features are shown. (2) The first mode represents an out-of-phase variation of the summer wind between southern and northern China. The associated principal component has significant interannual variability with 3-6 and 8 year periods. Correspondingly, the positive (negative) time coefficients, 850 hPa wind, 500 hPa geopotential height, and sea level pressure (SLP) anomalies exhibit the “-+-” (“+-+”) meridional tripole pattern in East China, from the western North Pacific (WNP), across Japan to the Okhotsk Sea. The summer precipitation tends to decrease (increase) in the middle and lower reaches of the Yangtze River, while it increases (decreases) over the east of northeast China, the southeast coast of China, and western Yunnan. (3) The second mode represents a consistency variation in the dominant mode of the EASM, which shows an interdecadal shift around 1993 and presents an alternating distribution with a quasi-12-year cycle. For a case with a positive (negative) time coefficient caused by the distribution of summer 850-hPa wind fields, there is an intensified anomalous anticyclonic circulation around Lake Baikal. There are also corresponding anomalous 500-hPa geopotential height fields exhibiting a “+-+” (“-+-”) anomalous zonal wave pattern over the midhigh latitudes, originating from western Europe, across the West Siberia plain, and extending to northeast Asia. The relationship between the second mode and the summer mean SLP is characterized by an almost positive (negative) correlation, which causes the weakening (strengthening) of the EASM. Meanwhile, the summer precipitation mode of “flooding in the south and drought in the north” (“drought in the south and flooding in the north”) appears. (4) The third mode reflects the westward and eastward movement of the EASM, which exhibits a 12-16-year periodic variation. When the time coefficient is in its positive (negative) phase, southerly (northerly) anomalies cover the areas east of 115o E, and northerly (southerly) anomalies appear in the region west of 115o E. The SLP and the 500-hPa geopotential height show very similar correlation patterns, i.e., a “-+” (“+-”) wave-train-like pattern from Okhotsk to the ocean east to Japan and an anomalous quasi-zonal teleconnection pattern in northern Eurasia. Nevertheless, the distribution of summer precipitation anomalies in most areas of China is negative (positive), with significant anomalies found only near the Huang-Huai basin.

     

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