A delayed action oscillator shared by biennial, interannual, and decadal signals in the Pacific Basin
A delayed action oscillator shared by biennial, interannual, and decadal signals in the Pacific Basin
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DOI：
10.1029/2002jc001490
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发表时间：
2003-03
影响因子：
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通讯作者：
W. White;Y. Tourre;M. Barlow;M. Dettinger
中科院分区：
文献类型：
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作者：
W. White;Y. Tourre;M. Barlow;M. Dettinger
[1]1955 - 1999年，太平洋海盆两年、年际和十年信号在海表温度（SST）、18°C等温线深度（Z18）、纬向表面风（WSW）和风应力旋度（WSC）的协变异常中具有相同的模式和演变。每个信号都有温暖的SST异常沿赤道沿着缓慢向东传播，在它们的尾迹中产生西风的COPWW异常。这些西风带的异常在赤道附近产生气旋性的WSC异常，在热带北太平洋的西部/中部产生斜压Rossby波。这些Rossby波向西传播，在两年、年际和十年周期尺度上分别需要106、1012和1036个月才能到达107 °N、1012 °N和1018 °N附近的西边界。在那里，它们反射为赤道耦合波，在协变SST、Z18和OPWW异常中缓慢向东传播，需要206、2012和2024个月才能到达赤道中东部海洋。这些赤道耦合波对该地区的暖海温异常产生延迟负反馈。Rossby波相速随纬度的减小、赤道海温异常的纬向尺度随周期尺度的增大以及Rossby波强迫随纬度的增大与用于解释厄尔尼诺的延迟振荡器（DAO）模型一致。然而，这是不正确的西边界反射的Rossby波到慢赤道耦合波。这需要修改现有的DAO模型。我们构建了一个修改后的DAO模型，演示了各种机制及其延迟的大小和来源如何产生每个信号的频率。
[1] Biennial, interannual, and decadal signals in the Pacific basin are observed to share patterns and evolution in covarying sea surface temperature (SST), 18°C isotherm depth (Z18), zonal surface wind (ZSW), and wind stress curl (WSC) anomalies from 1955 to 1999. Each signal has warm SST anomalies propagating slowly eastward along the equator, generating westerly ZSW anomalies in their wake. These westerly ZSW anomalies produce cyclonic WSC anomalies off the equator which pump baroclinic Rossby waves in the western/central tropical North Pacific Ocean. These Rossby waves propagate westward, taking ∼6, ∼12, and ∼36 months to reach the western boundary near ∼7°N, ∼12°N, and ∼18°N on biennial, interannual, and decadal period scales, respectively. There, they reflect as equatorial coupled waves, propagating slowly eastward in covarying SST, Z18, and ZSW anomalies, taking ∼6, ∼12, and ∼24 months to reach the central/eastern equatorial ocean. These equatorial coupled waves produce a delayed-negative feedback to the warm SST anomalies there. The decrease in Rossby wave phase speed with latitude, the increase in meridional scale of equatorial SST anomalies with period scale, and the associated increase in latitude of Rossby wave forcing are consistent with the delayed action oscillator (DAO) model used to explain El Nino. However, this is not true of the western-boundary reflection of Rossby waves into slow equatorial coupled waves. This requires modification of the extant DAO model. We construct a modified DAO model, demonstrating how the various mechanisms and the size and sources of their delays yield the resulting frequency of each signal.