Synoptic Climate Controls of Mass-Balance Variations on Devon Island Ice Cap

Abstract

Fourteen years (1961 through 1974) of synoptic weather charts for June through August were examined along with available meteorological and glaciological data from the northwest region of Devon Island ice cap, N.W.T., Canada. Use of a simple synoptic classification system facilitated investigation of the manner in which summer synoptic conditions control mass-balance fluctuations on the ice cap. Dominance of the Baffin Bay Cyclone suppresses melt and often results in solid precipitation. Cyclonic systems tracking into the region from elsewhere may also contribute to summer snow accumulation on the ice cap, but when the warm sector of such a system intrudes north of Devon Island substantial melt occurs on the ice cap and outlet glaciers. Sporadic anticyclonic periods produce proportionally more melt on the valley glaciers than over the ice cap but prolonged periods of anticyclonic blocking and warm air advection result in highly negative mass-balance conditions. A season dominated by anticyclonic conditions and the accompanying northward shift of the Arctic Front is capable of erasing the positive mass balance of five seasons dominated by the Baffin Bay Cyclone.