The dynamics of the ocean meridional overturning circulation.

海洋经向翻转环流(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，并有助于调节与大气的二氧化碳交换。然而，它对外部大气强迫变化的反应仍然缺乏了解和建模。在过去的二十年里，建模MOC对气候变化的反应需要高空间分辨率，这一点已经变得很明显。在南大洋尤其如此，南极绕极流(ACC)周围的地转湍流必须得到明确解决。目前的计算能力允许在全球模型中对MOC进行少量的涡旋解析模拟。然而，它不允许对参数空间进行更彻底的探索，例如完全理解管理动态所需的参数空间。相反，这类研究通常是使用更理想化的模型进行的。因此，在试图理解翻转环流动力学的理想化理论研究和试图准确模拟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)之间仍然存在着很大的差距。这项提议的总体目标是弥合这一差距。为此，我们将把一种强大的双向网格嵌套方法应用于GCM，以考虑更广泛的模型复杂性，并解决在以前的MOC理论研究中被忽视的关键过程的作用。我们将重点研究制约交通部的各种边界条件，并解决以下问题： 1)南极海冰在将沿着ACC向南流入南极底水地层的底层水与向北流动的表层Ekman层的底层水分开时起到了什么作用？ 2)地形引起的环流纬向不对称性对翻转环流有何影响？ 3)在一个代表南大西洋、太平洋和印度洋的多个盆地的系统中，MOC如何与绕极流联系起来？ 4)为什么西南极大陆架的水域变暖的速度比南极其他地区的水域更快？ 最终，拟议的研究将减少下个世纪气候预测中与经向翻转环流相关的不确定性。我们的研究还将提高我们对导致南极西部大陆架变暖的机制的理解，并有助于减少海平面预测中的不确定性。

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.