Linking oxygen and carbon uptake with the Meridional Overturning Circulation using a transport mooring array

Abstract

The Atlantic Meridional Overturning Circulation (AMOC) is a system of ocean currents that transports warm, salty water poleward from the tropics to the North Atlantic. Its structure and strength are monitored at several latitudes by mooring arrays installed by the international ocean sciences community. While the main motivation for deploying these mooring arrays is to understand the AMOC’s influence on Northern Hemisphere climate, the circulation system also plays a crucial role in distributing oxygen (O2) and carbon dioxide (CO2) throughout the global ocean. By adding O2 sensors to several of the moorings at 53°N–60°N (Figure 1) in the western Labrador Sea, Koelling et al. (2021) demonstrated that the formation of deep water, in which the AMOC brings surface water to the deep ocean, is important for supplying the oxygen consumed by deep-ocean ecosystems throughout the North Atlantic. Additionally, variability in the deep-water formation has been linked to changes in the amount of anthropogenic CO2 stored in the subpolar ocean (Raimondi et al., 2021). These studies, using data collected during research cruises and a small number of moored sensors, showed that deep-water formation and the AMOC are key to oxygen and carbon cycles in the North Atlantic. However, the common assumption that the magnitude and variability of O2 and CO2 uptake by the ocean are tied to the dynamics of the AMOC has never been evaluated on the basis of direct observations.