Four Decadal Ocean-Atmosphere Modes in the North Pacific Revealed by Various Analysis Methods
Four Decadal Ocean-Atmosphere Modes in the North Pacific Revealed by Various Analysis Methods
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DOI：
10.1023/a:1022831431602
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发表时间：
2002-12
影响因子：
2.3
通讯作者：
Jing‐Jia Luo;T. Yamagata
中科院分区：
文献类型：
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作者：
Jing‐Jia Luo;T. Yamagata
将各种统计方法(经验正交函数、旋转EOF、奇异值分解(SVD)、主振型(POP)、复合EOF(CEOF)和联合CEOF)应用于低通滤波(>；7年)海表温度(SST)、次表层温度和500hPA位势高度，以揭示北太平洋年代际变化的站立和传播特征。本研究共发现了四个年代际海气协变模。第一个模式是众所周知的类似ENSO的模式，与“太平洋-北美”大气模式有关，显示热带和温带外海温的变化是相反的。在热带西太平洋，次表层温度的变化与海温的变化是不同的。另外三种模式分别与副热带涡旋、阿拉斯加涡旋和副极地涡旋构成的海洋环流有关。1988/89年北太平洋事件与副热带涡旋模式密切相关，与副热带涡旋模式相关的大气类型为北极涛动。上层海洋热量收支分析表明，地面净热通量和平均涡旋平流对阿拉斯加涡旋模式有重要影响。对于亚极涡旋模式，平均涡旋平流、局地Ekman泵浦和地面净热通量起着重要作用。文中还讨论了北太平洋可能的海-气相互作用。这些年代际模式的海洋信号在北太平洋占据了厚厚的一层，因此累积的热含量可能反过来支持长期的气候变化。
Various statistical methods (empirical orthogonal function (EOF), rotated EOF, singular value decomposition (SVD), principal oscillation pattern (POP), complex EOF (CEOF) and joint CEOF) were applied to low-pass filtered (>7 years) sea surface temperature (SST), subsurface temperature and 500 hPa geopotential height in order to reveal standing and propagating features of decadal variations in the North Pacific. Four decadal ocean-atmosphere covariant modes were found in this study. The first mode is the well-known ENSO-like mode associated with the “Pacific-North American” atmospheric pattern, showing SST variations reversed between the tropics and the extratropics. In the western tropical Pacific, subsurface temperature variations were found to be out of phase with the SST variations. The other three modes are related to the oceanic general circulation composed of the subtropical gyre, the Alaskan gyre and the subpolar gyre, respectively. The 1988/89 event in the northern North Pacific was found to be closely associated with the subtropical gyre mode, and the atmospheric pattern associated with this mode is the Arctic Oscillation. An upper ocean heat budget analysis suggests that the surface net heat flux and mean gyre advection are important to the Alaskan gyre mode. For the subpolar gyre mode, the mean gyre advection, local Ekman pumping and surface net heat flux play important roles. Possible air-sea interactions in the North Pacific are also discussed. The oceanic signals for these decadal modes occupy a thick layer in the North Pacific, so that accumulated heat content may in turn support long-term climate variations.