Some evidence on the relationship between the South American monsoon and the Atlantic ITCZ
Some evidence on the relationship between the South American monsoon and the Atlantic ITCZ
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关于南美季风与大西洋 ITCZ 关系的一些证据
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
M. Kayano
中科院分区：
文献类型：
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作者：
S. R. Garcia;M. Kayano
本文利用1979-2006年的长波辐射（OLR）资料，分析了与南美季风系统（SAMS）有关的对流的季节变化。对0.4-1.2年的数据进行过滤，并应用经验正交函数（EOF）分析。结果表明，具有明显对流特征的三种主要模式分别为：赤道反对称模式、热带辐合带模式和对称模式。前两种模态以年为周期变化，后一种以半年为周期变化。通过将每个模态的主成分与滤波后的OLR时间序列进行相关（滞后和同步），研究了这些模态的演化方面。反对称模态和ITCZ模态相互平滑演化，反映了对流活动向西北和东北方向的传播。繁殖速率因发育阶段和所考虑的地区而异。另一方面，亚马孙西部对流活动最大的对称模态独立演化，描述了从干季到湿季的过渡，反之亦然。
The seasonal variations of convection associated with the South American monsoon system (SAMS) are analyzed using pentad means of outgoing longwave radiation (OLR) data during the 1979–2006 period. The data is filtered for the 0.4–1.2 year scale and an empirical orthogonal function (EOF) analysis is applied. The results provide three dominant modes with distinct convective features, which are referred to as: equatorially antisymmetric, intertropical convergence zone (ITCZ) and symmetric modes. The first two modes vary in an annual scale, and the latter one in a semiannual scale. The evolving aspects of these modes are studied by correlating (lagged and simultaneously) the principal component of each mode and the filtered OLR time series. The antisymmetric and the ITCZ modes evolve smoothly into each other reflecting the northwestward and northeastward propagation of convective activity. The propagation rates vary depending on development stage and region considered. On the other hand, the symmetric mode with the largest convective activity in the western Amazon evolves independently, and depicts the transition from dry to wet seasons and vice-versa.