Evidence for wind‐driven current fluctuations in the western North Atlantic

Abstract

Two subsurface current meter moorings were deployed for 20 months along 70°W in a low‐energy portion of the western North Atlantic. The resulting data were compared with estimates of the wind stress curl in an attempt to seek a relationship between currents below the mixed layer and meteorological forcing at subinertial frequencies. Currents and temperature tend to be significantly coherent with the curl and are most coherent with the curl at remote locations, usually more than 500 km away from the mooring and generally to the east. Coherences generally decrease with increasing frequency. The current response is surface intensified. A linear stratified model for stochastically wind‐forced Rossby waves in a flat‐bottomed ocean is presented as an attempt to rationalize the results. The effort was not entirely successful, so that it appears that a more realistic model, perhaps including bottom topography and mean currents, will be needed to rationalize these observations fully.