Investigation of summer synoptic climate controls on the mass balance of Meighen Ice Cap

Abstract

The Meighen Ice Cap synoptic climate classification system, developed from the study of six years of summer meteorological and glaciological observations, appears to account for significant variations in the energy‐ and mass‐balance climates of the ice cap. In relating the summer frequency of the three synoptic types to fourteen years of mass‐balance measurements, it was found that variations in surface conditions, solar angle and type of precipitation could be accounted for by the relative sequence of synoptic types. Further it was shown that the types could be represented by the position of the dominant 500‐mb cold Low influencing Meighen Island, thus providing a link between the mass balance and the general circulation.

Dominance of the winter pattern of a 500‐mb Low in the Hudson Bay –Baffin Island region throughout the summer season is capable of maintaining Meighen Ice Cap at its present size. A shift of the 500‐mb Low from the winter position directly to the Beaufort Sea or adjoining Polar Ocean area is capable of increasing the size of the ice cap. On the other hand, a shift of the 500‐mb vortex to the Asiatic side of the Polar Ocean before taking up position in the Beaufort Sea – Polar Ocean area produces negative mass‐balance conditions. When the 500‐mb Low remains on the Asiatic side of the Polar Ocean during most of the summer season the slow accumulation of two decades of Polar Ocean years is destroyed.