Transient ocean overturning response to changes in boundary conditions.

大气和海洋之间的热量和碳交换的速度强烈地影响着地球的气候。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，因此调节气候。海洋在这一过程中的作用不仅仅是被动的。这张图片的中心是海洋经向翻转环流(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。近年来，MOC与地面大气通量的相互作用主要集中在定常强迫下的长期平衡解上。然而，海洋很可能从未处于平衡状态，对瞬变气候变化更现实、依赖时间的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生物地球化学过程阐明海洋在瞬变气候变化问题中的作用。短期目标是将重点放在孤立地对短暂气候变化作出依赖时间的反应的三个关键方面。第一个方面涉及全球变暖条件下地表温度异常的响应。虽然地球表面的大部分地区都显示出正的温度异常，但在大西洋西北部仍观察到了一个令人惊讶的降温区域，称为“变暖洞”。为了了解这种结构是如何发展的，我们将研究地面风生涡旋与MOC深层路径之间的耦合作用。第二个方面涉及气候变化的极地放大。尽管交通部放缓，但在全球变暖的情况下，温暖的大西洋水域进入北极的流量预计将增加。为了了解控制海洋热量输送到北极的机制，我们将诊断北极倾覆环流，并研究河口型环流和风生型环流之间的耦合作用。第三个方面与最后一次冰川时期的气候变异性有关，当时发生了被称为丹斯加德-奥施格周期的气候突变。我们打算开发一个简单的预测框架，捕捉海-海-冰相互作用的主要特征，并研究其对全球碳循环的影响。总体而言，这项工作的完成将有助于减少气候模式中与倾覆环流有关的不确定性，改进对海洋热量向北极输送的预测，并澄清我们对控制倾覆变异性的关键机制的理解。通过改善气候预测，这项研究将帮助加拿大气候适应政策制定者为当地人口和行业做出更明智的决定。

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.