Modulation of the Eastern Equatorial Pacific Seasonal Cycle by Tropical Instability Waves
Modulation of the Eastern Equatorial Pacific Seasonal Cycle by Tropical Instability Waves
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DOI：
10.1029/2022gl100991
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发表时间：
2022-11
影响因子：
5.2
通讯作者：
L. Maillard;J. Boucharel;M. Stuecker;F. Jin;L. Renault
中科院分区：
文献类型：
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作者：
L. Maillard;J. Boucharel;M. Stuecker;F. Jin;L. Renault
使用两个涡旋丰富的海洋模拟，有和没有热带不稳定波（TIWs）的季节性循环的热带不稳定波（TIWs）的反馈研究。在北方夏季和秋季，通过非线性平流使赤道沃茨升温高达0.4°C，TIWs降低了海洋上层温度季节循环的幅度。此外，TIW通过增强正压能量转换稳定了赤道潜流（EUC）的上部，导致全年减弱−0.15 m s−1，并防止了通常在非涡动分解模式中发现的不切实际的北方降水再增强。水平分辨率为1度的粗糙模拟未能再现TIW引起的赤道沃茨非线性变暖，但成功地抑制了EUC的再强化。这表明TIW强度存在阈值效应，与模式模拟涡旋的能力有关，这可能是该地区全球气候模式长期存在的偏差的原因。
Feedbacks from tropical instability waves (TIWs) on the seasonal cycle of the eastern Pacific Ocean are studied using two eddy‐rich ocean simulations, with and without TIWs. By warming the equatorial waters by up to 0.4°C through nonlinear advection in boreal summer and fall, TIWs reduce the amplitude of the seasonal cycle in upper ocean temperatures. In addition, TIWs stabilize the upper part of the Equatorial Undercurrent (EUC) through enhanced barotropic energy conversion, leading to a year‐round weakening by −0.15 m s−1 and preventing an unrealistic re‐intensification in boreal fall usually found in non‐eddy resolving models. A coarser simulation at 1‐degree horizontal resolution fails to reproduce the TIW‐induced nonlinear warming of equatorial waters, but succeeds in inhibiting the EUC re‐intensification. This suggests a threshold effect in TIW strength, associated with the model's ability to simulate eddies, which may be responsible for long‐standing biases displayed by global climate models in this region.