Field Calibration of Mixed-Layer Drifters

Abstract

A set of field experiments was conducted to determine the water-following characteristics of mixed-layer drifters with ?holey-sock? drogues. Through the use of a drifting current meter array, direct estimates of slip velocity (or the difference between the velocity of the drifter and that of the water surrounding the drogue) were obtained with precision of better than ± 1 cm s?1. The range of slip velocities was 1 to 4 cm s?1, with the orientation of the slip principally in the downwind direction. The results are consistent with a simple model for slip induced by a wind-drift current, assuming a static balance of drag forces.