INTERANNUAL VARIABILITY OF SEA-ICE COVER IN HUDSON-BAY, BAFFIN-BAY AND THE LABRADOR SEA

The spatial and temporal relationships between subarctic Canadian sea- ice cover and atmospheric forcing are investigated by analysing sea-ic e concentration, sea-level pressure and surface air temperature data f rom 1953 to 1988. The sea-ice anomalies in Hudson Bay, Baffin Bay and the Labrador Sea are found to be related to the North Atlantic Oscilla tion (NAO) and the Southern Oscillation (SO). Through a spatial Studen t's t-test and a Monte Carlo simulation, it is found that sea-ice cove r in both Hudson Bay and the Baffin Bay-Labrador Sea region responds t o a Low/Wet episode of the SO (defined as the period when the SO index becomes negative) mainly in summer. In this case, the sea-ice cover h as a large positive anomaly that starts in summer and continues throug h to autumn. The ice anomaly is attributed to the negative anomalies i n the regional surface air temperature record during the summer and au tumn when the Low/Wet episode is developing. During strong winter west erly wind events of the NAO, the Baffin Bay--Labrador Sea ice cover in winter and spring has a positive anomaly due to the associated negati ve anomaly in surface air temperature. During the years in which stron g westerly NAO and Low/Wet SO events occur simultaneously (as in 1972/ 73 and 1982/83), the sea ice is found to have large positive anomalies in the study region; in particular, such anomalies occurred for a maj or portion of one of the two years. A spectral analysis shows that sea -ice fluctuations in the Baffin Bay-Labrador Sea region respond to the SO and surface air temperature at about 1.7-, 5- and 10-year periods. In addition, a noticeable sea-ice. change was found (i.e. more polyny as occurred) around the time of the so-called ''climate jump '' during the early 1960s. Data on ice thickness and on ice-melt dates from Hud son Bay are also used to verify some of the above findings.