Speaker: Xiaoting Yang
Title: "Sinking of Dense North Atlantic Waters in a Global Ocean Model: Location and Controls"
Abstract: The sinking of the convectively formed North Atlantic Deep Water (NACW) is the downwelling limb of the Atlantic Meridional Overturing Circulation (AMOC) which plays an important role in ocean circulation and global climate system. However, convection has been found to be more “mixing agents” with negligible net mass transport. Theoretical, numerical and laboratory studies have pointed out that the net vertical mass transport does not occur where the convection reaches the deepest level, but where dissipative processes, such as eddies or interaction with solid boundaries, are important due to the constraint of vorticity dynamics. This paper uses model simulations of high- and low-resolution configurations to study the distribution of net vertical mass transport. They found that in the high-resolution simulation, most of the net sinking happens near the coast and the water mass constantly experiences densification along its propagation path, consistent with theories. However, the agreement between the low-resolution simulation and the theories are less satisfactory, making it necessary for people to reflect on possible defects of low-resolution models in representing the ocean overturning circulation, considering their prevalent contribution in future climate projections. Paper