Decay of a High Arctic Lake Ice Cover

Abstract

<p>This is a study of the decay processes if an ice cover on a small Arctic lake. The study was carried out neat Resolute. N.W.T., Canada, for two melt seasons commencing in late May prior to melt and continuing until the lake was ice-free in late July. During this period, ice thickness, other ice properties and melt from the upper and lower ice surfaces were measured rapidly. In addition, environmental conditions which affect the melt rate, such as air and water temperatures and net radiation were obtained to permit a computation of the energy balance for the ice.</p> <p>A one-dimensional energy balance model used to calculate the ice melt, at a site performs well in predicting the ablation from the upper ice surfaces, melt from the lower ice surface and the internal melt and ice density. For the two study years, 49 percent of the melt (in water equivalent units) occurred in the ice interior due to absorbed radiation while ice melt at the upper ice surface (in water equivalent) amounted to 40 percent. Melt at the lower ice surface was only 11 percent of the total ice melt. Seventy five percent of the change in ice thickness occurred at the upper ice surface where much of the internal ice melt was concentrated, producing low surface ice densities.</p> <p>The formation of a moat along the edge of the ice cover and its subsequent growth was investigated. The results were incorporated in a two-dimensional model of ice decay along a transect normal to the shore. A series of transects allowed a simulation of the behaviour of the entire ice cover. The modelled results agree closely with the observed ice decay events from the beginning of melt until the fragmentation of the ice cover. Although the ice decay period was emphasized, the two-dimensional model can be expanded to include the season of ice growth.</p>