A Pathway for Northern Hemisphere Extratropical Cooling to Elicit a Tropical Response
A Pathway for Northern Hemisphere Extratropical Cooling to Elicit a Tropical Response
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DOI：
10.1029/2022gl100719
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发表时间：
2023-01
影响因子：
5.2
通讯作者：
Matthew T. Luongo;S. Xie;I. Eisenman;Yen‐Ting Hwang;Hung-Yi Tseng
中科院分区：
文献类型：
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作者：
Matthew T. Luongo;S. Xie;I. Eisenman;Yen‐Ting Hwang;Hung-Yi Tseng
以前的研究发现，北方半球气溶胶样冷却在热带印度太平洋引起了拉尼娜样反应。在这里，我们探讨了耦合的海洋-大气反馈途径如何沟通和维持这种反应。我们在一个综合气候模式中覆盖海洋表面风应力，将海洋-大气对强迫大气外冷却的总响应分解为单独的表面浮力强迫和单独的表面动量强迫的响应。在亚热带地区，浮力强迫响应占主导地位：正的低云反馈放大了海面温度（SST）异常，风驱动的蒸发冷却将其传递到热带地区。在赤道印度洋-太平洋，浮力驱动的海洋动力学使表面冷却，而Bjerknes反馈产生了纬向不对称的SST模式。虽然副热带云反馈依赖于模型，但我们的研究结果表明，这种反馈途径在一系列模型中是稳健的，因此具有较强副热带低云响应的模型表现出较强的拉尼娜响应。
Previous studies have found that Northern Hemisphere aerosol‐like cooling induces a La Niña‐like response in the tropical Indo‐Pacific. Here, we explore how a coupled ocean‐atmosphere feedback pathway communicates and sustains this response. We override ocean surface wind stress in a comprehensive climate model to decompose the total ocean‐atmosphere response to forced extratropical cooling into the response of surface buoyancy forcing alone and surface momentum forcing alone. In the subtropics, the buoyancy‐forced response dominates: the positive low cloud feedback amplifies sea surface temperature (SST) anomalies which wind‐driven evaporative cooling communicates to the tropics. In the equatorial Indo‐Pacific, buoyancy‐forced ocean dynamics cool the surface while the Bjerknes feedback creates zonally asymmetric SST patterns. Although subtropical cloud feedbacks are model‐dependent, our results suggest this feedback pathway is robust across a suite of models such that models with a stronger subtropical low cloud response exhibit a stronger La Niña response.