An ocean model’s response to North Atlantic Oscillation-like wind forcing


The response of the Atlantic Ocean to North Atlantic Oscillation (NAO)-like wind forcing has been investigated using an ocean-only general circulation model coupled to an atmospheric boundary layer model. A series of idealized experiments was performed to investigate the interannual to multi-decadal frequency response of the ocean to a winter wind anomaly pattern. South of 30 N, the sea surface temperature (SST) response of the model was almost exactly in phase with the forcing and largely independent of the forcing frequency suggesting that the subtropical ocean response to the overlying atmosphere is fast and direct. Poleward of 30 N and in particular in the Gulf stream extension region strong SST anomalies lagged the forcing by several years. They were sustained by deep reaching temperature anomalies which were then re-exposed to the atmosphere during the winter season. Overall the strength of the SST response increased slightly with longer forcing periods. In the subpolar gyre, however, the model showed a broad response maximum in the decadal band (12-16 years). The implications for the existence of a decadal coupled mode are discussed.

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@inproceedings{Visbeck1999AnOM, title={An ocean model’s response to North Atlantic Oscillation-like wind forcing}, author={Martin Visbeck and Heidi Cullen and Gerd Krahmann and Naomi H. Naik}, year={1999} }