Delayed influence of the Indian Ocean Dipole mode on the East Asia-West Pacific monsoon: possible mechanism
Delayed influence of the Indian Ocean Dipole mode on the East Asia-West Pacific monsoon: possible mechanism
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DOI：
10.1002/joc.1890
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发表时间：
2010-02-01
期刊：
影响因子：
--
通讯作者：
Chaudhari, H. S.
中科院分区：
文献类型：
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作者：
Kripalani, R. H.;Oh, J. H.;Chaudhari, H. S.
本文通过欧亚大陆油料复合和相关分析，探讨了东亚-西太平洋夏季风对印度洋偶极子模态（IODM）延迟响应的可能物理过程。识别承载此延迟响应的存储器的介质。结果表明，秋季偶极子的峰值正相位可以抑制三个季节后东亚地区的夏季风活动，特别是在韩日地区、华南地区和邻近的西太平洋地区。综合分析和相关分析表明，秋季偶极子正相可能在接下来的冬春两季在欧亚大陆东部（韩日半岛以北）地区引发暴雪。这可能会增加温度梯度，有利于在接下来的夏季在温暖的东亚-西太平洋地区从北向南输送寒冷和干燥的空气。海表温度（SST）表明，秋季偶极子模态的正相位与太平洋厄尔尼诺南方涛动（ENSO）的暖相位（El Nino）有关。随着季节进入夏季，太平洋上空的温暖阶段转变为发展中的寒冷阶段（拉尼娜现象），西太平洋上空的海温变暖。由大雪引起的异常北风和由拉尼娜引起的西太平洋海温异常偏暖使北太平洋副热带高压（NPSH）东移，形成弱的跨赤道气流和弱低空急流。这可能会抑制来自太平洋的水分供应，导致降雨活动减弱。3个季节后，东欧亚大陆地区的积雪分布通过北线携带了IODM延迟响应的足迹。此外，相关分析表明，与碘化的关系略强于与ENSO现象的关系。偏相关分析表明，东亚-西太平洋地区夏季风降水异常可能是由IODM和ENSO共同引起的。版权所有(C) 2009皇家气象学会
This study investigates the possible physical processes for the delayed response of the East Asia-West Pacific summer monsoon to the Indian Ocean Dipole Mode (IODM) through the Eurasian continent based oil composite and correlation analyses. The media carrying the memory for this delayed response is identified.Results reveal that the peak positive phase of the dipole during autumn could suppress the following summer monsoon activity over East Asia three seasons later, in particular over the Korea-Japan sector, South China and the adjacent West Pacific region. Composite and correlation analysis Suggests that the autumn positive phase of the dipole could induce heavy snow over Eastern Eurasia, north of the Korea-Japan (EENKJ) peninsula, during the following winter and spring seasons. This could increase the temperature gradient conducive to transport cold and dry air from the north towards South over the warmer East Asia-West Pacific domain during the following summer. The sea surface temperature (SST) reveals that the positive phase of the dipole mode during autumn is associated with the warm phase (El Nino) of the El Nino Southern Oscillation (ENSO) over the Pacific. As the seasons progress through to summer, the warm phase over the Pacific transforms to a developing cold phase (La Nina) with warmer SSTs over the West Pacific. Both the anomalous northerly winds due to heavy snow and the anomalous warm SST over the West Pacific due to La Nina displace the North Pacific Subtropical High (NPSH) eastwards, resulting in a weak cross-equatorial flow and a weak low-level jet. This could inhibit moisture supply from the Pacific leading to Subdued rainfall activity. The footprints of the IODM for delayed response, three seasons later, could be carried by the snow distribution over Eastern Eurasia by the northern route. Furthermore, correlation analysis suggests that the relationships with IODM are slighter stronger than with the ENSO phenomenon. However, partial correlation analysis probably Suggests that both the IODM and ENSO work cooperatively for the summer monsoon rainfall anomalies over East Asia-West Pacific region. Copyright (C) 2009 Royal Meteorological Society