The shallow limb of the Atlantic meridional overturning circulation: variability and impacts on the ocean's carbon and nutrient reservoirs

北大西洋副极地是一个强烈的海气相互作用导致温跃层沃茨转变为被称为北大西洋深水（NADW）的水团集合的区域。 NADW淹没了盆地的深层和中层，为全球变化找到其海洋表现形式提供了一条途径。 转化为NADW的前体沃茨部分来自亚热带水团，据认为，这些水团进入副极地环流的程度随时间而变化。 控制翻转运输及其时间变化的基本机制仍然知之甚少，对海洋内部热量，碳和营养库的影响也是如此。为了探测海洋环流和海洋地球化学性质的人为变化，我们必须加强对造成这种变化的机制的理解。 因此，所提出的工作要解决的基本问题是：什么是主导机制设置的时间变化的大西洋翻转运输？ 这种变化对NADW的地球化学性质有何影响？ 工作将围绕3个目标进行： 1.在大气环流模式中描述MOC的变化机制，其对人为变化的脆弱性，以及其对海洋碳和营养库的影响。 2. 调查水文任务、卫星产品和近二十年来北大西洋剖面浮标收集的数据中出现的变化和趋势。 3.在麦吉尔建立一个计划，收集大西洋翻转环流浅翼的直接观测结果。 这一目标包括建立一个实验室，用于在形成水团的恶劣海洋环境中自主收集观测结果。

The subpolar North Atlantic is a region where intense air-sea interactions cause the transformation of thermocline waters into of a collection of water masses known as North Atlantic Deep Water (NADW). The NADW floods the deep and intermediate depths of the basin and provides a pathway for global change to find its oceanic expression. The precursor waters that are transformed to become NADW stem partly from subtropical water masses, whose penetration into the subpolar gyre is thought to vary temporally. The basic mechanisms that govern the overturning transport and its temporal variability remain poorly understood, as do the implications for the ocean's interior heat, carbon, and nutrient reservoirs. In order to detect anthropogenic change in the ocean's circulation and biogeochemical properties, we must enhance our understanding of the mechanisms causing this variability. Therefore, the fundamental questions to be addressed by the proposed work are: What are the dominant mechanisms setting the temporal variability of the Atlantic overturning transport? What are the consequences of such variability on the biogeochemical properties of the NADW? The work will be organized around 3 objectives: 1. Characterize mechanisms governing variability in the MOC, its vulnerability to anthropogenic change, and its impacts on the ocean's carbon and nutrient reservoirs in a General Circulation model. 2. Investigate the variability and trends emerging in observational data from hydrographic missions, satellite products, and nearly two decades of data collected by profiling floats in the North Atlantic. 3. Build a program at McGill that will collect direct observations of the shallow limb of the Atlantic overturning circulation. This goal includes the mounting of a lab for the autonomous collection of observations in the harsh ocean environments in which water masses are formed.