Role of AMOC in Transient Climate Response to Greenhouse Gas Forcing in Two Coupled Models
Role of AMOC in Transient Climate Response to Greenhouse Gas Forcing in Two Coupled Models
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DOI：
10.1175/jcli-d-19-1027.1
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发表时间：
2020-07-15
影响因子：
4.9
通讯作者：
Nadiga, Balu T.
中科院分区：
文献类型：
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作者：
Hu, Aixue;Van Roekel, Luke;Nadiga, Balu T.
随着温室气体浓度的增加，预计气候将变暖。然而，许多内部气候过程可以调节气候系统对不断上升的温室气体强迫的主要辐射变暖响应。在这里，我们关注的特定内部气候过程是大西洋经向翻转环流（AMOC），它是海洋环流的一个重要的全球范围特征，用于输送热量和其他标量，我们解决了 AMOC 的平均强度如何调节瞬态气候响应的问题。虽然社区地球系统模型版本 2 (CESM2) 和能源百兆亿级地球系统模型版本 1 (E3SM1) 具有非常相似的平衡/有效气候敏感性，但我们的分析表明，较弱的 AMOC 在一定程度上导致了对 E3SM1 中温室气体强迫上升的瞬态气候响应更高，因为它允许上层海洋更快变暖，同时地下海洋变暖更慢。同样，CESM2 中更强的 AMOC 通过允许上层海洋变暖更慢，在一定程度上导致了更小的瞬态气候响应。因此，虽然 AMOC 的平均强度不影响平衡/有效气候敏感性，但它可能在确定百年时间尺度上的瞬态气候响应方面发挥重要作用。
As the greenhouse gas concentrations increase, a warmer climate is expected. However, numerous internal climate processes can modulate the primary radiative warming response of the climate system to rising greenhouse gas forcing. Here the particular internal climate process that we focus on is the Atlantic meridional overturning circulation (AMOC), an important global-scale feature of ocean circulation that serves to transport heat and other scalars, and we address the question of how the mean strength of AMOC can modulate the transient climate response. While the Community Earth System Model version 2 (CESM2) and the Energy Exascale Earth System Model version 1 (E3SM1) have very similar equilibrium/effective climate sensitivity, our analysis suggests that a weaker AMOC contributes in part to the higher transient climate response to a rising greenhouse gas forcing seen in E3SM1 by permitting a faster warming of the upper ocean and a concomitant slower warming of the subsurface ocean. Likewise the stronger AMOC in CESM2 by permitting a slower warming of the upper ocean leads in part to a smaller transient climate response. Thus, while the mean strength of AMOC does not affect the equilibrium/effective climate sensitivity, it is likely to play an important role in determining the transient climate response on the centennial time scale.