CGRG Bibliography of Canadian Geomorphology
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Author : Cogley, J.G.
Date : 2003.
Title : Phase correction of elevation differences between glacier surveys.
Publication : Technical Note. Department of Geography, Trent University, Peterborough.
Issue : 2003-3.
Page(s) : 3 p.
Abstract
Geodetic estimates of glacier mass balance are derived from differences between surface elevations measured at different times, usually several years apart. The difference in time is not in general an integer multiple of one year, but the surface elevation generally exhibits a marked annual cycle. In the simplest case, the elevation changes steadily during the year due to dynamics, falling in the accumulation zone and rising in the ablation zone. The mass balance, however, is seasonal: the surface rises due to net accumulation in winter and falls due to net ablation in summer. Surveys made at di erent times of year will therefore be out of phase, and a phase correction is desirable. Assume that the annual cycle is unvarying and, for the moment, that the glacier is at equilibrium. The first assumption is only an approximation but is necessary unless information at seasonal resolution happens to be available. The second assumption is not likely to be correct, but nor is it likely to introduce any significant error. It also simpli es the picture because the annual cycle of surface elevation may now be viewed (Figure 1) as a triangle whose base, at elevation zero, is the balance year and whose apex is the maximum seasonal elevation at the end of winter.
Bibliography of Canadian Geomorphology