POAC 09 - Bedford Institute of Oceanography

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Figure 3. Mean sea level pressure from 01 Aug to 06 Aug 2008. A B C D E F Fig. 4. AMSR-E images from 31 July to 13 August 2008. Bright tones indicate high ice concentrations. DRIFT FROM JONES SOUND TO DAVIS STRAIT On 15 September 2008, two satellite-tracked ice beacons were deployed from the icebreaker CCGS Amundsen via helicopter by Dr. Martin Fortier on the ice island in northern Baffin Bay northeast of Jones Sound. The beacons were deployed about 2.5 km apart along the long axis of
the ice island. A photograph of the ice island taken on 15 September is shown in Fig. 5; freeboard estimates of the ice island were not obtained. Fig. 5. Petermann ice island, with CCGS Amundsen in foreground on 15 Sept 2008 at 76.4°N, 77.0°W (Photo courtesy of Dr. M. Fortier (University of Laval)). A CALIB ARGOS ice beacon manufactured by Metocean Data Systems was deployed for the Canadian Ice Service and provided position data with an accuracy of about 300 m. A prototype Iridium beacon built at the Bedford Institute of Oceanography which was designed to transmit hourly GPS fixes, was also deployed. The beacon was deployed following replacement of batteries, and provided about 2 weeks of position data before it malfunctioned. The CEP accuracy is less than 2.5 m, where CEP (Circular Error Probability) is the radius of a horizontal circle, centered at the antenna’s true position, containing 50% of the fixes. Soon after deployment northeast of Jones Sound, the beacons drifted southwestward, making several clockwise loops (Fig. 6). Rotary motion may be due to tidal currents, or to inertial currents which are circular motions in a clockwise direction in the northern hemisphere. The period of the oscillations was consistent with both the inertial period (12.3 hours at 76.35°N) and the M2 tidal period (12.4 hours). However, the eastward component was not in phase with that predicted by the WebTide Tidal Prediction Model (DFO, 2009), suggesting the oscillations are primarily inertial. The amplitude of the inertial oscillations was about 0.2 m/s, which is consistent with the amplitude of intertial oscillations observed in northwest Baffin Bay with current meters: 0.1-0.2 m/s, with speeds as high as 0.35 m/s (Fissel, 1981). Inertial oscillations are generally a response to individual wind events, and decay after a few cycles. Wind data from the area (Fig. 7) shows that the oscillations were preceded by strong northeasterly winds on day 258 (14 Sept).
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Page 3: across Nares Strait adjacent to the
Page 7 and 8: is superimposed on a contour map of
Page 9 and 10: CONCLUSIONS AND DISCUSSION Understa

POAC 09 - Bedford Institute of Oceanography

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