Glaciological investigations, Nunatarssuaq ice ramp, northwestern Greenland PDF Download

Author: Laurence H. Nobles
Publisher:
ISBN:
Category : Glaciers
Languages : en
Pages : 79

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Book Description
The margin of the ice cap in northwestern Greenland is formed by a relatively thin ice carapace resting on a very rugged sub-ice togography. The Nunatarssuaq ice ramp is a gently sloping ice mass approximately 4 miles long by 2 miles wide that forms part of this margin 30 miles northeast of Thule. The ice of the Nuna ramp is of subpolar type, in which negative temperatures prevail throughout most of the year in all but the upper few feet. At a depth of 25 ft the ice temperature is constant throughout the year at -14C; only the upper 2-3 ft of ice is at 0C by the end of the melt season. Thus the temperature regimen of this high-polar ice is strictly analagous to that of perennially frozen ground. All runoff is on the surface, forming such surface features as slush avalanches, algal pits, and an integrated drainage pattern. Net accumulation as high as 25 in. of water equivalent was measured at Morris Station, 30 miles from the border of the ice cap, but most of the Nuna ramp proper is blown free of snow in winter by strong winds. Ablation of 20 to 25 in. of water during the melt season is common on the lower Nuna ramp. The most severe ablation is on days of moderately high temperature accompanied by moderate winds. The firn limit on the ramp is at about 3000 ft elevation. Comparison between the total amount of ice ablated from the lower ramp and the amount delivered to the ramp by flow through the gap south of Nuna Knob indicates a strongly negative budget balance for the ramp during the period studied.