Changes in the Northwest Atlantic circulation for the 1992–95 high NAO period from a numerical model

Present research suggests that the North Atlantic Oscillation (NAO) has a significant impact on the circulation in the Northwest Atlantic. An ocean general circulation model was used to quantify the changes of circulation patterns and transport on this region during a high NAO period (between 1992 and 1995) when compared to climatological mean forcing. Upstream of the study region, the maximum barotropic transport in the Labrador Sea was decreased by 8 Sv (1 Sv=106 m3s−1) during the high NAO conditions, leading to a reduction in transport of the Labrador Current by ∼1.6 Sv east of Newfoundland and by ∼0.4 Sv south of Newfoundland. In addition, a Lagrangian analysis was performed to examine the pathways of transport that advect water properties across the Grand Banks and how those pathways are modified owing to the high-NAO forcing. The potential implications of these changes for biological production processes in the adjacent downstream shelf regions such as the Scotian Shelf, Gulf of Maine, and Georges Bank are discussed.