LINKING TEMPERATURE OF THE NORTHWEST ATLANTIC AND ATLANTIC MERIDIONAL OVERTURNING CIRCULATION (AMOC)
Abstract
The Northwest Atlantic Shelf and Slope is a region where cold waters transported southward in the Labrador Current can encounter warmer waters of the Gulf Stream. Increasing the proportion of Gulf Stream waters causes warming of the Northwest Atlantic Shelf, as was observed after 2008. This shift toward more Gulf Stream waters was linked to the greater eastward diversion of the Labrador Current near the Tail of the Grand Banks of Newfoundland (TGB) after 2008. Because the Labrador Current carries some of the dense waters of the equatorward branch of the Atlantic Meridional Overturning Circulation (AMOC), we hypothesize that the Labrador Current’s eastward diversion could signify an AMOC slowdown. Using two eddy-resolving ocean models, we explore the connection between Northwest Atlantic Shelf and Slope warming and AMOC decline. The first model uses realistic atmospheric forcing to simulate the years 1978-2017. The second model is a fully ocean-atmosphere coupled climate model run for hundreds of years with preindustrial concentrations of greenhouse gases in the atmosphere. The results show that warming in the Northwest Atlantic Shelf and Slope is correlated with slowing of the AMOC. It also shows that interannual variability in equatorward transport of dense waters at the TGB is highly correlated with the full, cross-basin AMOC.