Ocean response to decadal shifts in the air-sea interaction over the North Atlantic

The atmosphere and ocean of the North Atlantic have undergone significant changes in the past century. To understand these changes,their mechanisms, and theirregional implications requires a quantitative understanding of processes in the coupled ocean and atmosphere system. Central to this understanding is the role played by the dominant patterns of ocean and atmospheric variability which define coherent variations in physical characteristics over large areas.
We present results from a study of the decadal shifts in the atmospheric circulation over the North Atlantic and the long term ocean response. The decadal variations in the atmosphere are characterized by changes in the phases of two asymmetrical “modes” which were found representative for the long term variations of the phase of the North Atlantic Oscillation and for the spatial shifts in the positions of its centers over Iceland and Azores. The ocean response to this variability accounts for major patterns in the observed decadal changes of the North Atlantic Ocean water mass characteristics and circulation over the past fifty years.