Impact of Equatorial Wind Change on the Meridional Heat Transport in the Atlantic

Sanjana Satish, Kaila Uyeda, C Spencer Jones

Ocean heat transport in the Atlantic basin is northwards at all latitudes, and is largest between the equator and 42 degN. This heat transport impacts multiple aspects of the Earth's climate, setting tropical precipitation, surface temperatures and Arctic sea ice concentration. In this paper, we attempt to understand the role of the equatorial winds in setting the meridional heat transport in the Atlantic using an idealized single basin model with a re-entrant channel in the southern boundary. Increasing the westward wind stress at the equator increases the volume transport of the subtropical cells. Although the wind stress changes are symmetric about the equator, we find that the heat transport in the Northern Hemisphere changes more than the heat transport in the Southern Hemisphere. We find that heat transport changes are mediated by the western boundary currents, which are warmer when the winds are stronger at the equator. This heat continues poleward until it reaches the poleward boundary of the subtropical gyre (STG), after which waters cool down due to exposure to colder subpolar atmospheric temperatures. A further series of experiments run with a 20% decrease in AMOC shows that the AMOC has very little impact on the fate of heat that enters the ocean in the equatorial Atlantic.