Assessment of the water-following capabilities of CODE drifters based on direct relative flow measurements

Abstract

Direct measurements of the relative water flow near the top and bottom of Coastal Ocean Dynamics Experiment (CODE) drifters were made in the northeast Pacific Ocean and the Mediterranean Sea in wind speeds as large as 15ms-1. These measurements confirmed that the CODE drifter is a good Lagrangian drifter with a mean downwind slip of about 0.1% of the wind speed. Substantial mean vertical shears across the drifter (top 1m below the surface) were observed, reaching an amplitude of 12 cms-1 and corresponding to strong stratification (due to the proximity of river runoff) and strong winds.