Heat transport analyses of the tropical Atlantic ocean mixed layer using satellite based observations

Using observations primarily from satellite platforms a three-dimensional heat transport analysis is constructed for the mixed layer of the tropical Atlantic Ocean on timescales from monthly to interannual. Advection is analyzed using surface currents derived from satellite sea surface height, surface vector winds, and sea surface temperature (NOAA, Ocean Surface Current Analysis – Real Time, 1993-2004). Surface heat fluxes are from NCEP and various other sources including satellite based observations. The ocean mixed layer depth is determined by various climatological mixed layer depth products, and for the anomaly analyses numerical model mixed layer depths are used. Sea surface temperature from satellite observations determines the temperature of the mixed layer. Analysis equations allow for the inference of vertical entrainment at the base of the mixed layer, and the residual includes fine scale turbulent heat fluxes not resolved by the observations in addition to (of course) errors. Results indicate that entrainment tends to oppose the other terms of the analysis and reduce the residual. The residual tends to be largest in three regions: 1) the equatorial cold tongue, 2) near the western basin just north of the equator where the north Brazil current bifurcates, and 3) near the eastern basin between 5°N and 10°N corresponding with the seasonally varying trough associated with the NECC/NEC. The third region is also influenced by seasonally varying upwelling that occurs off the northwest African coast.