Current and Density Observations across the Wake of Hurricane Gay

Abstract

CTD and acoustic Doppler current profiler data are analyzed for the response of the upper ocean to rapidly moving Hurricane Gay. Currents were observed within about two days of the hurricane passage and were dominated by a blue-shifted inertial oscillation confined largely to the mixed layer. The amplitude of the current was strongly asymmetric about the track, with the largest amplitude, 1 m s?1, about 80 km to the right of the track. There was also an asymmetry of the mixed layer depth and temperature with deeper and cooler values to the right of the track. The gradient Richardson number was found to have low values, in some places less than 1/4, in a layer from 10 to 30 m thick below the base of the surface mixed layer. This suggests that shear flow instability played an important role in the vertical mixing that occurred within the mixed layer and upper thermocline.