AIDJEX Bulletin #40 - Polar Science Center - University of Washington

the ice (causing reduced shear). An interesting event is apparent beginning
about day 360 in the 30 m speed at M/O 1 (Figure 13). Note that the current
speed is sustained at a level appreciably higher than the ice speed for several
days. A similar event occurs at buoy M/O 4 about 10 days later. It is
possible to conjecture that the events are from the same baroclinic disturbance
which is propagating eastward at about 40 cm sec-l (the buoys are
approximately 400 km apart). There is also a sustained current during
February, March, and April 1976 at M/O 4 in the absence of much ice drift.
The current is apparently westward, as would be expected in the southern
part of the gyre.
CONCLUSIONS
Ocean current measurements from the buoys are encouraging for more
widespread studies of near-surface currents under sea ice. Although the
buoys were experimental, and suffered some shortcomings due to lack of
experience, they did provide new observations of inertial oscillations,
propagating mesoscale features, and persistent westerly currents in the
southern Beaufort Sea. The magnetic compass appears to have produced good
azimuth data. We have had trouble interpreting the current meter directional
measurements and consider some of the directional data suspect; however,
this may be more due to prejudice from previous ice station experience
rather than the actual evidence from the buoys. We do point out that when
a towing velocity is provided by the ice, the directional measurement
requires higher precision to determine the actual current direction to the
same accuracy than if the current meter were fixed. This is something that
should be considered in the design of future buoys. It also seems well
within present technical capability to provide vectoT averaging of measured
currents. The installation would be greatly simplified if current meters
suspended more than a €ew meters below the buoy hull were equipped with compasses
so that the rigid mast could be eliminated. Sensitive water
temperature sensors seem feasible and would be useful, particularly during
the summer months, to indicate the amount of stratification near the surface.
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