On Anomalous Ocean Heat Transport toward the Arctic and Associated Climate Predictability

It is commonly understood that the potential for skillful climate prediction resides in the ocean. The observed poleward propagation of ocean temperature anomalies in the North Atlantic Ocean has in particular been suggested as a primary source for predictability. It is nevertheless presently unresolved to what extent anomalous ocean heat interacts with the atmosphere to realize its predictive potential. The propagation and drivers of interdecadal heat anomalies with the Atlantic thermohaline circulation’s northernmost limb and their atmospheric interaction are assessed from observations and a multi-century climate model simulation. Ocean heat anomalies propagate from the subpolar North Atlantic, into, and through the Nordic Seas. The ocean's influence on the atmosphere, and hence regional climate, is manifested by anomalous ocean heat convergence in the Nordic Seas driving subsequent changes in surface heat fluxes and surface air temperature. The coherence between the ocean and the atmosphere is manifested in a common and dominant 14─15-year time scale of variability. Rooted in the persistent poleward propagation of heat anomalies we show that the interannual change in northwest European climate can be skillfully predicted with a forecast horizon of one to nine years.