Tidal Currents and Inertial Oscillations in Northwestern Baffin Bay

From moored current meter data obtained in 1978 and 1979 in western Baffin Bay and Lancaster Sound, a preliminary analysis was made of the tidal currents and interial oscillations in the area. The tidal currents are relatively small through much of the study area. Offshore, the largest of both the diurnal and the semi-diurnal tidal currents were in all cases less than 8 cm/s in amplitude. In nearshore locations, the tidal currents can be considerably stronger due to internal tides; for example, off Cape Hay on Bylot Island, the K1 tidal currents near the surface were determined to have an amplitude of 15 cm/s. Evidence of inertial oscillations was present in the records from the uppermost current meters on all moorings located at a nominal depth of 35 m. Typical amplitudes were 10 to 20 cm/s, with speeds as high as 35 cm/s being observed. The magnitude of inertial oscillations decreases rapidly with depth; at 250 m, they are greatly reduced in amplitude and are difficult to resolve from the semi-diurnal tidal currents. The inertial oscillations resulted, in large part, from changes in the local surface wind; at times of solid ice cover, their amplitudes were markedly reduced.Key words: Baffin Bay, tidal currents, inertial oscillations, circulatio

Seasonal Variations in Currents and Water Properties in Northwestern Baffin Bay, 1978-1979

Year-long records of current speed and direction, temperature and conductivity were obtained from five current meter moorings in northwestern Baffin Bay. Significant seasonal changes in all these parameters were found, which closely followed the seasonal cycle of sea-ice cover. A general winter weakening of the near-surface currents (by a factor of 2 or more) was observed. Deeper currents exhibited a smaller decrease, resulting in a general decrease in baroclinicity during the winter. An exceptional case was observed off the north coast of Bylot Island, where the deep currents reversed. An increase in salinity combined with freezing temperatures was observed in the upper part of the water column during the winter. At some sites this uniform layer appeared to deepen at a steady rate of approximately 40-50 m per month, to a maximum depth between 200 and 250 m. It was not possible, however, to distinguish between the effects of local convection and horizontal advection in deepening the layer.Key words: current, seasonal variation, temperature, salinity, Arctic, Lancaster Sound, Baffin Ba

Major Features of the Summer Near-Surface Circulation of Western Baffin Bay, 1978 and 1979

In the summers of 1978 and 1979, an extensive physical oceanographic program was carried out in western Baffin Bay and Lancaster Sound. Data collected include satellite-tracked drifter measurements, CTD profiles and time series of subsurface currents. They indicate that the near-surface circulation of the area is dominated by the southward-flowing Baffin Current. This current, observed to extend at least as far north as Lady Ann Strait (76° N) and south to Cape Dyer (67° N), is largely confined to within 100 km of the coastline. It varies in both intensity and width with the strongest flows occurring where the current follows a cyclonic intrusion into and out of eastern Lancaster Sound; here in the core of the current the median near-surface (4 to 11 m) speeds are 75 cm/s, decreasing to 50 cm/s at 40 m depth and 25 cm/s at 250 m depth. To the east of Devon, Bylot and Baffin islands, the current is well-defined, but generally less intense with typical near-surface speeds of 30 cm/s. Important spatial variations occurred in the circulation of the area. In eastern Lancaster Sound, two distinct and alternating flow patterns were observed in the strong intrusive current in the summer of 1979. Transient large-scale meanders of the circulation were detected in the offshore portion of the Baffin Current off the east coasts of Bylot and Baffin islands. Between the eastern coastline of Bylot Island and the core of the southeasterly flowing Baffin Current, anticyclonic eddies of approximately 20 km diameter occasionally occurred.Key words: Baffin Bay, Baffin Current, circulation, Lancaster Sound, oceanography, surface currents, sub-surface current