Sea surface height changes in the North Atlantic Ocean related to the North Atlantic Oscillation

Interannual sea surface height (SSH) variability as measured by the Topex/Poseidon satellite altimeters is investigated for the North Atlantic Ocean between 1992 and 1998. The SSH variability exhibits a basin-wide coherent dipole structure between the subtropical and the subpolar North Atlantic. The SSH dipole pattern changed sign between 1995 and 1996, coinciding with a change of sign of the North Atlantic Oscillation (NAO). The large-scale SSH pattern is reproduced with an ocean general circulation model, and can be traced back to changes in the atmospheric forcing related to the NAO. The model reveals that the interannual SSH anomalies are mainly caused by changes in the oceanic heat transport which are connected with the response of the large-scale ocean circulation to changes in the wind stress curl. Variations in the local heat flux reinforce these SSH anomalies but axe of minor importance.