doi:  10.3878/j.issn.1006-9895.1712.17177
AMO正、负位相背景下欧亚夏季副热带波列季节内活动特征及其与印度降水的联系

Modulation of the Atlantic Multidecadal Oscillation on intraseasonal activity of the Eurasian summer subtropical wavetrain and Indian rainfall
摘要点击 1600  全文点击 224  投稿时间:2017-06-07  修订日期:2017-09-30
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基金:  国家自然科学基金41375085
中文关键词:  北大西洋年代际振荡, 欧亚夏季副热带波列, 季节内变化, 印度夏季降水
英文关键词:  The Atlantic Multidecadal Oscillation, Eurasian summer subtropical wavetrain, Indian summer rainfall, Intraseasonal variability, Modulation
     
作者中文名作者英文名单位
孙雪倩SUN Xueqian中国科学院大气物理研究所CCRC
李双林LI Shuanglin中国科学院大气物理研究所CCRC
引用:孙雪倩,李双林.2018.AMO正、负位相背景下欧亚夏季副热带波列季节内活动特征及其与印度降水的联系[J].大气科学
Citation:SUN Xueqian,LI Shuanglin.2018.Modulation of the Atlantic Multidecadal Oscillation on intraseasonal activity of the Eurasian summer subtropical wavetrain and Indian rainfall[J].Chinese Journal of Atmospheric Sciences (in Chinese)
中文摘要:
      利用美国国家环境预测中心与国家大气研究中心(NCEP-NCAR)逐日再分析资料,针对北大西洋多年代际振荡(AMO)两个不同位相,对逐候200hPa经向风异常进行EOF分析,发现在AMO正、负位相期间,欧亚副热带波列的季节内活动存在明显差异。利用超前滞后回归,对比了不同AMO位相下副热带波列及其相联系的印度夏季降水的季节内活动演变特征,分析有关的大气环流,探究波列影响降水的机制。结果表明:在AMO负位相期间,由格陵兰岛以南北大西洋经大不列颠岛、地中海、黑海-里海向南亚北部传播的副热带波列的季节内演变,在印度中部引起下沉,导致中部及西北部季节内降水减少,波列负位相相反;在AMO正位相期间,副热带波列西起冰岛以南北大西洋经丹麦南部、俄罗斯西部、中亚向南亚东北部传播,对应该波列的季节内演变,辐合上升区在印度中部和东西两侧,使得该区域季节内降水增加,波列负位相相反。于是,AMO通过调制夏季欧亚副热带波列的季节内活动,可以对印度夏季降水的季节内变化空间型及演变发挥显著影响。 关键词 北大西洋年代际振荡,波列,季节内变化,印度夏季降水 中图法分类号
Abstract:
      By using daily variables of the NCEP/NCAR reanalysis, this study compares the intraseasonal activity of the Eurasian summer subtropical wavetrain during the two opposite phases of the Atlantic Multidecadal Oscillation (AMO). Significant difference is found based on pentad mean 200-hPa meridional wind components. The associated Indian summer precipitation intraseasonal variability is also different during the two AMO phases. Then lead-lag regressions of 500hPa wind field and the vertical motion are conducted to illustrate the AMO’s modulation on the subtropical wavetrain and the Indian summer rainfall. The results suggest that the intraseasonal evolution of the positive-phase subtropical wavetrain has positive centers over Great Britain, Black-Caspian Sea but negative centers over the north Atlantic south of Greenland, the Mediterranean and north of South Asia in 200-hPa heights during the AMO negative phase. This induces an anomalous subsidence and reduced rainfall in central and northwestern India. It is opposite for the negative-phase subtropical wavetrain. In contrast, during the AMO positive phase, the positive-phase subtropical wavetrain originates from the North Atlantic south of Iceland and propagates toward northeastern South Asia via southern Denmark, western Russia and Central Asia.The interseasonal evolution of this wavetrain leads to an anomalous convergence and increased rainfall in much of India. It is opposite for the negative-phase subtropical wavetrain. This study highlights the AMO’s modulation on the intraseasonal variability of Indian summer rainfall through influencing the Eurasian summer subtropical wavetrain.
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