The dynamics of the ocean meridional overturning circulation.

海洋经向翻转环流的动力学。

• 批准号: RGPIN-2015-06712
• 负责人: Nadeau, LouisPhilippe
• 金额: $ 1.75万
• 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: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=680022
• 关键词: dynamics; ocean; meridional; overturning; circulation.

The ocean meridional overturning circulation (MOC) plays a key role in the climate system: it controls the amount of heat stored in the deep ocean and helps regulate the exchange of CO2 with the atmosphere. Yet, its response to changes in external atmospheric forcing is still poorly understood and modeled. Over the last twenty years, it has become clear that modeling the response of the MOC to climate change requires high spatial resolution. This is especially true in the Southern Ocean, where geostrophic turbulence around the Antarctic Circumpolar Current (ACC) must be explicitly resolved. Current computing power allows for a small number of eddy-resolving simulations modeling the MOC in global models. It does not, however, allow for a more thorough exploration of the parameter space, such as is required to fully understand the governing dynamics. Instead, such studies are typically carried out using more idealized models. As a result, there still exists a very wide gap between the idealized theoretical studies that attempt to understand the dynamics of the overturning circulation and the more realistic General Circulation Model (GCM) simulations that attempt to mimic accurately the MOC and predict its response to climate change. The overall goal of this proposal is to bridge this gap. To do this, we will apply a powerful two-way grid nesting approach to a GCM in order to consider a much wider range of model complexities and address the role of key processes that have been neglected in previous theoretical studies of the MOC. We will focus on various boundary conditions constraining the MOC and address the following questions: ***1) What is the role of Antarctic sea ice in partitioning the bottom water upwelling along the ACC that flows south to feed the Antarctic Bottom Water formation from that which flows north in the surface Ekman layer?***2) What is the effect of the ACC's topography-induced zonal asymmetry on the overturning circulation?***3) How does the MOC connect with the circumpolar current in a setup with multiple basins, representing the south Atlantic, Pacific and Indian Oceans?***4) Why are the waters of the West Antarctic continental shelf warming at a faster pace than waters along the rest of the Antarctic? ***Ultimately, the proposed research will reduce the uncertainty related to the meridional overturning circulation in the climate projections of the coming century. Our research will also improve our understanding of the mechanisms causing warming on the West Antarctic continental shelf and help reduce the uncertainty in the sea level projections.**

海洋纬向翻转环流（MOC）在气候系统中起着关键作用：它控制着深海中储存的热量，并有助于调节CO2与大气的交换。然而，它对外部大气强迫变化的响应仍然知之甚少，模型。在过去的二十年中，人们已经清楚地认识到，模拟MOC对气候变化的响应需要高的空间分辨率。在南大洋尤其如此，南极绕极流（ACC）周围的地转湍流必须明确解决。目前的计算能力允许在全球模型中对MOC进行少量的涡分辨模拟。然而，它不允许更彻底地探索参数空间，如需要充分理解的动态管理。相反，这些研究通常使用更理想化的模型进行。因此，在试图理解翻转环流动力学的理想化理论研究与试图准确模拟MOC并预测其对气候变化的响应的更现实的大气环流模式（GCM）模拟之间仍然存在很大的差距。本提案的总体目标是弥合这一差距。为了做到这一点，我们将采用一个强大的双向网格嵌套方法的GCM，以考虑更广泛的模型复杂性，并解决的关键过程中被忽视的作用，在以前的理论研究的MOC。我们将集中在各种边界条件限制的MOC和解决以下问题：*1）南极海冰的作用是什么分区底层水涌上沿着ACC向南流动，以养活南极底层水的形成，从那些流向北方的表面埃克曼层？* 2)ACC地形引起的纬向不对称对翻转环流有什么影响？*** 3)MOC如何与环极流在多个盆地的设置中连接，代表南大西洋，太平洋和印度洋？* 4)为什么西南极大陆架的沃茨比南极其他沿着的沃茨变暖的速度更快？* 最终，拟议的研究将减少未来世纪气候预测中与纬向翻转环流有关的不确定性。我们的研究还将提高我们对西南极大陆架变暖机制的理解，并有助于减少海平面预测的不确定性。