Wind Drag and Relative Separations of Undrogued Drifters

Abstract

This is an analysis of the movement of six satellite-tracked (Nimbus 6) drifters which had lost their drogues. An attempt was made to correct the drifter velocity records for wind drag. The corrections, however, were unrealistically large at high winds, thus implying that the uncorrected records were a better representation of the ocean currents. Pair separations were calculated for three pair combinations. The pairs depolyed together and 200 km apart separated at an average rate of 1–2 km per day over several months. However, the pair deployed 400 km apart showed a net convergence. It is speculated that the convergence was due to entrainment in the flow along the subtropical front.