| 南半球夏季纬向平均环流的垂直结构异常及其与AAO和ENSO的联系 |
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| 引用本文： | 白莹莹,管兆勇,张焱.南半球夏季纬向平均环流的垂直结构异常及其与AAO和ENSO的联系[J].地球物理学报,2009,52(11):2689-2697. |
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| 作者姓名： | 白莹莹 管兆勇 张焱 |
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| 作者单位： | 1.重庆市气象科学研究所，重庆 401147;2.南京信息工程大学大气科学学院，KLME，南京 210044;3.重庆市气象台，重庆 401147 |
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| 基金项目： | 国家自然科学基金项目，重庆市自然科学基金重点项目，中国气象局成都高原气象研究所开放实验室基金项目 |
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| 摘 要： | 利用NCEP/NCAR月平均再分析资料，研究了南半球夏季（12~2月）纬向平均环流的垂直结构异常及其与南极涛动（AAO）和ENSO的联系.结果表明，南半球夏季纬向平均［u］的异常分布的主要模态（EOF1）显示出极区、50°S~70°S、以及50°S以北的区间内“三极”型振荡.EOF1 既反映了AAO的特征又与ENSO有着显著的关系.由于AAO指数与Nino3区指数之间存在着统计相关，为进一步弄清AAO和ENSO在南半球纬向平均气流变动的相关分量及其结构，利用Nino3区指数使用一元回归方法滤除ENSO影响，再对剩下的部分作EOF分解，得到了独立于ENSO的纬向平均［u］的第一模态AEOF1.相关分析表明AEOF1为与AAO相对应的纬向平均［u］异常的分布.用南半球纬向平均［u］去掉其与AAO相联系的模态AEOF1，进行EOF分解得到的第一模SEOF1，其与Nino3 区指数的相关高达0.9.由此给出了纬向平均气流的变动与ENSO无关的模态和与ENSO有关的模态.时间变化分析表明，近30年中，除了年代际变化和3~7年的年际变化外，纬向平均的纬向基本气流尚有极地西风减弱、副极地西风加强、副热带西风减弱、热带东风加强的长期趋势.
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| 关 键 词： | 南半球夏季 纬向平均 AAO ENSO |
| 收稿时间： | 2008-9-1 |
| 修稿时间： | 2008-12-1 |
Vertical structure of zonal-mean circulation anomalies in the Southern Hemisphere in austral summer and its relationship with AAO and ENSO |
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| BAI Ying-Ying,GUAN Zhao-Yong,ZHANG Yan.Vertical structure of zonal-mean circulation anomalies in the Southern Hemisphere in austral summer and its relationship with AAO and ENSO[J].Chinese Journal of Geophysics,2009,52(11):2689-2697. |
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| Authors: | BAI Ying-Ying GUAN Zhao-Yong ZHANG Yan |
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| Institution: | 1.Chongqing Institute of Meteorological Sciences, Chongqing 401147, China;2.Institute of Atmospheric Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, China;3.Chongqing Meteorological Office, Chongqing 401147, China |
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| Abstract: | The NCEP/NCAR reanalysis data have been employed to diagnose variations of the zonal-mean zonal flow in the Southern Hemisphere in austral summer.Only is one leading EOF mode (EOF1) found to dominate the spatial and temporal changes of the austral summertime (12～2 month) zonal-mean zonal winds in the troposphere.Variations of u] as shown by EOF1 is found to be relate to AAO and ENSO.In order to further understand the influences of AAO and ENSO on the Southern zonal-mean zonal flow,we have performed the EOF analysis for the zonal mean zonal wind anomalies after the Nino3 signals has been removed from the wind anomalies using the regression method,by which the leading EOF mode (AEOF1) yields.This EOF1 is statistically independent of ENSO.However,the AEOF1 displays a structure of the zonal-mean zonal flow that closely relates to Antarctic Oscillation (AAO).To examine the ENSO related component in zonal flow,the EOF analysis has been performed for the Southern zonal-mean flow from which the AEOF1 has been removed.The new leading EOF mode (SEOF1) has hence been obtained,which is highly correlated with Nino3 index (correlation coefficient: 0.9).The SEOF1 shown that the eastlies in the tropics and the westlies in middle latitudes be weakened (strengthened) in the Southern Hemisphere during the El Nino (La Nina) years.Interestingly,the long term trend is observed in the leading mode of the zonal mean zonal flow,showing that the westlies over polar and subtropical regions had been weakening during the past 30 years.However,the westlies over subpolar regions and eastlies in tropical regions had been simultaneously strengthening during the same period of time. |
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| Keywords: | Austral summer Zonal-mean AAO ENSO |
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