Drifting buoy trajectories in the North Atlantic Current

Abstract

Despite intensive research, there are still large gaps in our knowledge of the North Atlantic Current which is considered to be the link between the Gulf Stream off the east coast of North America and the anomalously warm surface waters off northwestern Europe. In the classical scheme given in Fig. 1, which was constructed by Dietrich¹ on the basis of data obtained during 1957–58, the current is seen to comprise several branches. Two important difficulties arise from this interpretation. First, the data for the area east of Newfoundland are not sufficient to define the causes of why the branching of the North Atlantic Current is stationary in its source area over the slope off Grand Banks². Second, rapid surveys of the oceanic temperature structure by means of expendable sondes and, increasingly, of long-term moored instrumentation and satellite-tracked drifting buoys³ have revealed that the oceanic current field is dominated by mesoscale eddies and meanders rather than by large-scale steady flows. We report here two experiments using satellite-tracked buoys which address these difficulties. Our results clarify the pathway of the North Atlantic Current and confirm that the current indeed consists of mesoscale eddies and meanders.