The anomalous sea-ice extent in Hudson bay, Baffin bay and the Labrador sea during three simultaneous NAO and ENSO episodes

The nature of the sea-ice extent in Hudson Bay, Baffin Bay and the Labrador Sea associated with the three strong simultaneous NAO (North Atlantic Oscillation) and ENSO (El Nino-Southern Oscillation) episodes of 1972/73, 1982/83 and 1991/92 is investigated. During the first year of the 1972/73 episode, when positive sea surface temperature (SST) anomalies occurred in the eastern tropical Pacific from January 1972 to February 1973 and the Icelandic Low substantially deepened in winter 1973, there were heavy ice conditions (large positive sea-ice extent anomalies) in the study region and negative SST anomalies in the Labrador Sea and northwestern North Atlantic Ocean, north of 50°N. The anomalous ice conditions are attributed to the coincident large-scale negative surface air temperature (SAT) and positive northerly wind anomalies in the region. Ten years later, during 1982/83, the strongest ENSO event of the past century occurred, and extremely large positive sea-ice extent anomalies persisted in the Baffin Bay-Labrador Sea region for almost two years. This response was also due to negative anomalies in the SAT for much of this period, as well as very strong northerly winds in the Labrador Sea associated with a deepened Icelandic Low during autumn 1982 and winter 1983. During the winter of 1991/92, severe ice conditions were observed off Newfoundland, in response to local negative SAT anomalies and a strong NAO event. Cross-correlations between the regional SAT anomalies and the sea-ice area anomalies, as well as the SO (Southern Oscillation) and NAO indices for the period 1953-90, provide further support for the above findings.