Spring-season climate variability in the central Canadian Arctic Islands

Abstract

The Resolute Bay area in the central Canadian Arctic Islands is in a region of maximum variability in 50 kPa heights in spring. This is the northern part of an oscillation in large-scale atmospheric circulation called the Baffin Island West Atlantic Oscillation (BWA). The historical record of temperature at Resolute Bay, Northwest Territories, over the 1948–93 period is compared with circulation patterns for extremely warm and cold spring seasons, using a composite technique and a simple index of the intensity of the BWA. The extremely cold spring of 1992, the second coldest of the 46a record, was probably caused by reduced solar radiational forcing due to the increased dust veil caused by Mount Pinatubo.Within each spring season, large-scale synoptic conditions provided an important control on the timing of critical stages leading to full snow melt on the sea-ice surface. The first stage is the change from dominance of the region by wintertime continental polar air to the frequent invasion of maritime polar air masses, resulting in increased cloud cover and reduced frequency of Arctic inversions. The second stage is the transition to full melt on the ice with a sharp drop in surface albedo. During the spring on 1993, the first stage was triggered by a major storm which moved through the area on 9–10 May 1993. The second snow-melt stage was triggered by a stationary upper ridge which remained over the area for a 2 week period from 15 May to early June and produced clear to scattered-cloud conditions and high downward solar radiation.