Measurement of nearsurface current in Cape Cod Bay using sighted drogues

Abstract

During July 16-19, 1979 currents in Cape Cod Bay from the very near surface to 1.8 m were measured by taking simultaneous bearings on submerged drogues from two anchored vessels. The error in drogue position as a function of location with respect to the two vessels was examined in detail and was used for rejecting or accepting velocities from particular sightings. From the final results well defined velocity shears, nearly parallel with the wind, were evident. From these velocity fields surface stress coefficients, equivalent sand-grain roughness coefficients, and the near surface gradients of relative (to the surface velocity) velocity were calculated.