Corresponding author: Rebecca Woodgate (firstname.lastname@example.org)
|Between 1986 and 1997, moorings were deployed
in the Beaufort Sea as part of a joint US-Canadian project.
The coverage varies from year to year as can be seem from this schematic of the mooring locations.
The boundary current along the Beaufort slope shows frequent reversals, at least in part associated with long wave propagation, but the mean flow is clearly cyclonic, even though the flow of ice and near-surface water is westward. Both plumes and eddies may help move shelf waters offshore across the slope, where the boundary current is the dominant feature. In addition to dispersing shelf waters, the boundary current likely also acts as a source of offshore waters for the shelf during pulses of onshore flow associated with upwelling events near the shelf break. In the Beaufort Sea the latter can reach 400 m in amplitude.
Seaward of the Beaufort Sea slope and below
the mixed layer, the most energetic part of the velocity field resides in
eddies with a typical horizontal length scale of 10-20 km. We find
that in the pycnocline, the time history of the T/S correlation at a fixed
location is complex, with clouds of outlier points. The temperature
excursions are particularly large, probably because for cold water, temperature
has a lesser effect on density than does salinity, and temperature excursions
are therefore less constrained by buoyancy forces. Combined velocity
and T/S records provided convincing evidence of baroclinic eddies embedded
in the pycnocline, and the data show the frequent passage of both horizontally
and vertically paired counter-rotating eddies drifting past the monitoring
site. Sharp frontal passages are also visible in these data, and the
overall impression is of an interior ocean with considerable horizontal and
vertical structure, and with a decidedly grainy T/S field. We also
find long-term (months or more) changes in the elevation of isopycnal surfaces
by tens of meters, with corresponding changes in the thickness of the upper
layer. These changes likely represent either shifts in the location
of the Beaufort gyre or changes in the circulation strength, or both.
We gratefully acknowledge financial support
for this work from the Office of Naval Research (ONR), High Latitude
Dynamics program, and the Minerals Management Service (MMS).
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