Structure and evolution of interannual variability of the tropical Pacific upper ocean temperature
Structure and evolution of interannual variability of the tropical Pacific upper ocean temperature
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DOI：
10.1029/96jc01805
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发表时间：
1996-09
影响因子：
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通讯作者：
Rong‐Hua Zhang;S. Levitus
中科院分区：
文献类型：
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作者：
Rong‐Hua Zhang;S. Levitus
本文分析了1961-1990年热带太平洋高空海温异常资料，揭示了热带太平洋上层海温年际变化的主导结构和演变过程。我们使用多元经验正交函数(EOF)分析来检测与厄尔尼诺现象有关的主要三维结构。在赤道和赤道外热带北太平洋地区存在明显的海锯结构，其特征是具有相反的异常极性。厄尔尼诺年间，赤道以东和热带中上层海温异常为正。伴随而来的是西部地下深度的相应负异常，最大值出现在赤道外100-150米处。不同于海表面温度的变化主要局限在东部，只有一个主要的极性，而50-200m深度的温度变化在赤道中部太平洋和热带北太平洋西部具有偶极子模式，具有异相振荡。在拉尼娜年间，观测到了这些异常的相反模式。厄尔尼诺和拉尼娜之间的演变涉及赤道盆地和赤道外热带北太平洋异常位相的显著纬向转移，表现出从西到东、从次表层到海面、从赤道上到赤道外的一致和一致的变化。这种位相传播在次表层比海面更为明显，表明热带北太平洋赤道附近的距平场连续向东向西移动，在经度上具有纬向传播的空间不均一性。我们的分析提供了热带太平洋次表层海洋深处温度异常演变方式的证据，从而为评估理论研究和模型模拟提供了观测基础。本文还讨论了这些结果的动力学意义。
n n Yearly in situ temperature anomaly data for the period 1961-1990 are analyzed to reveal the dominant structure and evolution of interannual variability of the tropical Pacific upper ocean. We use multivariate empirical orthogonal function (EOF) analyses to detect the principal three-dimensional structure related to El Nino. There are well-defined subsurface thermal patterns, characterized by a prominent sea-saw structure with opposite anomaly polarity in the equatorial and off-equatorial tropical North Pacific regions. During an El Nino year a positive temperature anomaly is found in the-e-astern and central tropical upper ocean. This is accompanied by a corresponding negative anomaly at subsurface depths in the west, with a maximum at 100-150 m off the equator. Unlike sea surface temperature, whose variations are confined largely to the east with one dominant polarity, temperature variations at 50-200 m depths have a dipole pattern with out-of-phase oscillations in the central equatorial Pacific and in the western tropical North Pacific. A reverse pattern of these anomalies is observed during a La Nina year. Evolution between El Nino and La Nina involves a significant zonal transfer of anomaly phase across the equatorial basin as well as across the off-equatorial tropical North Pacific, showing consistent and coherent variations from west to east, from subsurface to sea surface, and from on the equator to off the equator. This phase propagation is more evident at subsurface depths than that at the sea surface, suggesting a continual movement of anomaly pattern in succession, eastward along the equator and westward off the equator of the tropical North Pacific, with spatial inhomogeneities of zonal propagation in longitude. Our analyses present evidence of the manner in which temperature anomalies evolve at subsurface ocean depths in the tropical Pacific, thus providing an observational basis for evaluating theoretical studies and model simulations. The dynamical implication of these results is also discussed.