Kelly, K. A., University of Washington, Seattle, USA, firstname.lastname@example.org
Thompson, L. ., University of Washington, Seattle, USA, email@example.com
Dickinson, S. ., University of Washington, Seattle, USA, firstname.lastname@example.org
THE COHERENCE OF UPPER OCEAN HEAT TRANSPORT IN THE WESTERN NORTH ATLANTIC
The coherence of heat transport in the upper 800m of the western North Atlantic is tracked using a thermodynamics-only model, with geostrophic surface velocities specified from altimetric sea surface height and the vertical profile derived from hydrographic data. The model comprises an upper ocean mixed layer and interior layers forced by geostrophic advection. The pathways of mass and temperature transport are examined from the Gulf Stream's separation to beyond the trifurcation into the North Atlantic Current (NAC), the Azores Current, and the southern recirculation return flow. The pathways are complex and vary significantly with time, with surprisingly little coherence in transports along the Gulf Stream itself. Inflow anomalies from the Labrador Current are well-correlated with those in the North Atlantic Current; both are lag-correlated with the NAO and with the Sverdrup transport. The Gulf Stream mass and temperature transport variations are only weakly correlated with either the NAC or the NAO. This description of heat and mass transports bears little resemblance to an ocean heat conveyor belt, at least for the upper limb, and reveals instead nearly independent fluctuations on interannual time scales. The heat budget of the region where the subpolar and subtropical gyres interact (the intersection of the Labrador Current, North Atlantic Current, and Gulf Stream) is examined in detail to determine the heat source for the relatively warm North Atlantic Current.
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