Upper ocean velocities in the Beaufort Gyre

Abstract

A 23 month time series of upper ocean velocities in the Beaufort Gyre was obtained from an autonomous drifting buoy equipped with an Acoustic Doppler Current Profiler. The buoy was deployed in the Beaufort Sea and drifted over the Canada Basin, Chukchi Shelf, and Chukchi Plateau. Time-evolving spectral analysis was used to examine velocity variability in three frequency bands: an eddy band (2-5 day periods), a diurnal band, and a semidiurnal band. The eddy band and the semidiurnal band dominated the horizontal kinetic energy. Although eddy energy was clearly confined to the Beaufort Sea and Canada basin, eddies were found further to the south and west than in previous observations. The semidiurnal band was dominated by near-inertial motions with amplitude that varied seasonally (largest in late summer and smallest in late winter). Diurnal tides were weak (< 1 cm s-1) except over a shallow portion of the Chukchi Shelf.