Sea surface temperature anomalies due to anomalous oceanic heat fluxes

The heat fluxes in the upper tropical oceans as modeled by NCAR's Upper Ocean Model (UOM) are analyzed on seasonal and interannual time scales. UOM is forced with estimates of the observed momentum, heat and fresh water fluxes. The contributions of the ocean's lateral and vertical heat fluxes to sea surface temperature anomalies (SST) are compared with the atmospheric fluxes. A lag correlation analysis indicates where the ocean dynamics plays an active in creating the SST and where it merely serves as heat storage.

While the active role of the ocean in creating the SST anomalies in the eastern Pacific is well known, our analysis of the oceanic heat fluxes in the western tropical Pacific outside the equatorial wave guide during the 1997/98 ENSO event points to an active role of the ocean in this area as well.

The heat flux analysis is complemented by an integration of an atmospheric climate model of intermediate complexity coupled to an underlying slab oceanic mixed layer. A missing SST anomaly in the western off-equatorial Pacific these simulations corroborate our result that oceanic heat fluxes are the cause of these anomalies.