Transient ocean overturning response to changes in boundary conditions.

瞬态海洋翻转对边界条件变化的响应。

• 批准号: RGPIN-2022-04306
• 负责人: Nadeau, LouisPhilippe
• 金额: $ 2.19万
• 依托单位: Université du Québec à Rimouski
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=765286
• 关键词: Transient; ocean; overturning; response; changes

The rate at which heat and carbon are exchanged between the atmosphere and ocean strongly influences the Earth's climate. In this context, the ocean can be seen as a huge reservoir that stores atmospheric tracers and, as a result, regulates the climate. The ocean's role in this process is not solely passive. At the center of this picture is the ocean meridional overturning circulation (MOC). The MOC sets the amplitude and spatial structure of oceanic heat and carbon absorption and redistributes these tracers into the abyss. Recent advances the MOC's interaction with surface atmospheric fluxes has focused primarily on long-term equilibrium solutions under steady forcing. However, the ocean has most likely never been in a state of equilibrium and many aspects of the more realistic time-dependent response to transient climate change remain poorly understood. The long-term goal of this research proposal is to clarify the ocean's role in the transient climate change problem through physical and biogeochemical processes. The short-term goals are to focus on three key aspects of the time-dependent response to transient climate change in isolation. The first aspect relates to the surface response in temperature anomaly under global warming. While most of the surface of the globe shows positive temperature anomalies, a surprising region of cooling, called "warming hole", is nonetheless observed in the northwestern Atlantic. In order to gain understanding of how this structure develops, we will investigate the coupled interaction between the surface wind-driven gyres and the deeper pathways of the MOC. The second aspect relates to the polar amplification of climate change. The flux of warm Atlantic waters into the Arctic is predicted to increase under global warming despite the slowdown of the MOC. In order to understand what mechanisms control the oceanic heat transport into the Arctic, we will diagnose the Arctic overturning circulation and investigate the coupled interaction between an estuary-type circulation and a wind-driven-type circulation. The third aspect relates to climate variability during the last glacial period when abrupt climate variations, called Dansgaard-Oeschger cycles, took place. We intent to develop a simple predictive framework that captures the main characteristics of the coupled ocean-sea-ice interaction and investigate its effect on the global carbon cycle. Overall, the completion of this work will help reduce uncertainty related to the overturning circulation in climate models, improve predictions in ocean heat transport into the Arctic, and clarify our understanding of key mechanisms controlling the variability of the overturning. By contributing to improvements in climate projections, this research will help Canadian climate adaptation policy makers take more informed decisions for local populations and industry.

热量和碳在大气和海洋之间交换的速率强烈影响着地球的气候。在这种情况下，海洋可以被视为一个巨大的水库，储存大气示踪剂，从而调节气候。海洋在这一过程中的作用并不完全是被动的。在这张图片的中心是海洋纬向翻转环流（MOC）。MOC设定了海洋热量和碳吸收的幅度和空间结构，并将这些示踪剂重新分配到深渊中。MOC与地面大气通量的相互作用的最新进展主要集中在稳定强迫下的长期平衡解。然而，海洋很可能从未处于平衡状态，对瞬态气候变化的更现实的时间依赖性反应的许多方面仍然知之甚少。这项研究提案的长期目标是通过物理和地球化学过程澄清海洋在瞬时气候变化问题中的作用。短期目标是集中注意孤立地对瞬时气候变化作出依时间而定的反应的三个关键方面。第一个方面涉及全球变暖条件下温度异常的地表响应。虽然地球仪的大部分表面显示出正的温度异常，但在大西洋西北部仍然观察到一个令人惊讶的冷却区域，称为“变暖洞”。为了了解这种结构是如何发展的，我们将研究表面风驱动的涡旋和MOC的更深路径之间的耦合相互作用。第二个方面涉及气候变化的两极放大作用。尽管MOC减缓，但在全球变暖的情况下，预计温暖的大西洋沃茨流入北极的流量将增加。为了了解是什么机制控制海洋热量输送到北极，我们将诊断北极翻转环流，并研究河口型环流和风驱动型环流之间的耦合相互作用。第三个方面与末次冰期的气候变化有关，当时发生了突然的气候变化，称为丹斯加德-厄施格循环。我们打算开发一个简单的预测框架，捕捉耦合的海洋-海冰相互作用的主要特征，并调查其对全球碳循环的影响。总的来说，这项工作的完成将有助于减少气候模型中与翻转环流相关的不确定性，改善对海洋热量输送到北极的预测，并澄清我们对控制翻转变化的关键机制的理解。通过促进气候预测的改进，这项研究将有助于加拿大气候适应政策制定者为当地人口和工业做出更明智的决定。