Meridional heat transports in the ocean from an ECCO2 data synthesis

A global ocean data synthesis product at eddy-permitting resolution from Estimating the Circulation and Climate of the Ocean, Phase II (ECCO2) project are used to estimate the total and eddy merdional heat transports in the ocean. These estimates are compared to previous observational and modeling studies. The contributions of the overturning and the horizontal circulations to the total heat transport are evaluated. The eddy heat transport was estimated as the deviation of the zonally integrated heat transport from its 3-month averages. The estimated heat transport, thus, contains signals only with periods shorter than 3 months, which are mainly associated with the eddy variability. We show that in a number of locations the time-mean eddy heat transport constitutes a considerable portion of the total time-mean heat transport, in particular, in the tropics, in the Southern Ocean and in the Kuroshio Current. This research demonstrates that the variability of the eddy heat transport is a significant contributor to the variability of the total heat transport and globally it explains about 1/3 of its variance. Eddies are also found to explain a significant portion of the seasonal-interannual heat transport variance. Using the estimates of the meridional heat transport we investigate the mechanisms of the recent sea level rise in the Subpolar North Atlantic and demonstrate the importance of the oceanic heat convergence.