Meridional Overturning Circulation in a multi-basin model. Part II: Sensitivity to diffusivity and wind in warm and cool climates
Meridional Overturning Circulation in a multi-basin model. Part II: Sensitivity to diffusivity and wind in warm and cool climates
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多流域模型中的经向翻转环流。
DOI：
10.1175/jpo-d-20-0121.1
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发表时间：
2021
影响因子：
3.5
通讯作者：
Baker J
中科院分区：
文献类型：
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作者：
Baker J
在不同浮力强迫（对应于“温暖”、“当今”和“冷”状态）下，研究了经向翻转环流（MOC）对南大洋（SO）纬向风强迫和太平洋海盆垂直扩散率变化的响应。在由南部绕极通道连接的两个海盆环流模式中。我们发现，大西洋MOC（AMOC）加强与增加SO风应力或扩散率在模式太平洋，在所有浮力强迫。的AMOC风应力的敏感性增加的浮力强迫是从一个温暖的变化到现在的一天或冷的状态，而它是最敏感的太平洋扩散率在现在的一天或温暖的状态。同样，在风应力减小或太平洋扩散系数增强的情况下，AMOC对南大洋的浮力强迫更敏感。出现这些结果是因为太平洋路径在温暖的气候中的重要性增加，使盆地之间的联系增加，因此太平洋的扩散率有机会影响大西洋的翻转。在较冷的状态下，如在冰川气候中，这两个盆地在很大程度上是分离的，SO上的风强度是AMOC强度的主要决定因素。风和扩散驱动的上升流维持AMOC在温暖（今天）的状态。SO风应力的变化单独不浅滩的AMOC类似于观察到的末次冰期最大的浮力强迫的变化也需要解耦的两个盆地。
The response of the meridional overturning circulation (MOC) to changes in Southern Ocean (SO) zonal wind forcing and Pacific Ocean basin vertical diffusivity is investigated under varying buoyancy forcings, corresponding to “warm,” “present day,” and “cold” states, in a two-basin general circulation model connected by a southern circumpolar channel. We find that the Atlantic MOC (AMOC) strengthens with increased SO wind stress or diffusivity in the model Pacific, under all buoyancy forcings. The sensitivity of the AMOC to wind stress increases as the buoyancy forcing is varied from a warm to a present-day or cold state, whereas it is most sensitive to the Pacific diffusivity in a present-day or warm state. Similarly, the AMOC is more sensitive to buoyancy forcing over the Southern Ocean under reduced wind stress or enhanced Pacific diffusivity. These results arise because of the increased importance of the Pacific pathway in the warmer climates, giving an increased linkage between the basins and so the opportunity for the diffusivity in the Pacific to affect the overturning in the Atlantic. In cooler states, such as in glacial climates, the two basins are largely decoupled and the wind strength over the SO is the primary determinant of the AMOC strength. Both wind- and diffusively driven upwelling sustain the AMOC in the warmer (present day) state. Changes in SO wind stress alone do not shoal the AMOC to resemble that observed at the last glacial maximum; changes in the buoyancy forcing are also needed to decouple the two basins.