Mesoscale meridional heat transport inferred from sea surface observations

Abstract

The ocean regulates the Earth's climate by transporting heat from the equator to the poles. Here, we use satellite-based sea surface observations of air-sea heat fluxes and eddy detection to investigate the mesoscale heat transport. “Mesoscale” refers to both the Eulerian perspective as the spatio-temporal scales of ∼100 km and ∼1 month, as well as the Lagrangian aspect as isolated vortices identified from the dynamic topography. Paradoxically, there are a considerable number of mesoscale eddies inconsistent between their surface thermal and dynamic signals, that is, cold-core anticyclones and warm-core cyclones are globally prevalent. On account of such inconsistency, we show that the mesoscale meridional heat transport carried by geostrophic components is 10 times larger than (and opposite in direction to) that of the wind-driven Ekman components. An offset between SSH-SST coherent and incoherent eddies in the Ekman heat transport is apparent, whereas the geostrophic heat transport is contained within coherent eddies.