Observations of internal waves and eddies in the Beaufort Sea during the winter of 1993/94

Acoustic Doppler current profiler observations obtained at the Sea Ice Mechanics Initiative (SIMI) ice camp in the Beaufort Sea during the winter of 1993/94 are used to document internal wave and mesoscale variability. The upper-ocean velocity was profiled to depths of approximately 250 meters. Initially (December 1993–January 1994), the camp drifted westward through the central Canada Basin (75N, 139–153W). During February–March 1994, the camp drifted meridionally along 156W (near the Northwind Ridge), reversing direction several times.; A large population of typical Beaufort Sea vortices was observed in the central basin. These vortices extended between the base of the mixed layer and approximately 200 meters depth. The 10 kilometer diameters of these eddy cores appeared to be in solid body rotation, with the azimuthal velocity fields detectable over distances greater than 30 kilometers. These eddies rotated anticyclonically between 0.7 and 0.9 revolutions per day.; In spite of the passage of atmospheric storms, internal wave energy in the central basin was low, averaging 1/25 of the Garrett-Munk (GM) standard. Shear variance averaged 1/17 GM.; Near the Northwind Ridge, large baroclinic vortices were not detected. Smaller mesoscale features (60–100 meters in vertical extent), centered at a variety of depths in the upper water column, were encountered. Comparison to more recent observations suggests that the separation between the areas occupied by the large and the small mesoscale structures is a characteristic feature of the Canada Basin.; Internal wave energy levels near the Northwind Ridge increased significantly, peaking at 1/6 GM. Shear variance peaked at 1/3 GM. Much of this increase was associated with (surface generated) downward propagating, near-inertial waves.; High ice-to-water relative velocities (atmospheric storms), accompanied by ice deformation, appear in general to be necessary, but not sufficient, to assure a downward propagating wave generation event. The highly variable mesoscale has a significant effect on the near-inertial wavefield propagation. The increase in wave energy as the ice camp left the central basin is jointly associated with the passage of storms and the absence of large baroclinic vortices.