Abstract
ABSTRACTThe extensive dataset of Variegated Glacier's 1982/83 surge and antecedent quiescent phase is fragmentary and predominantly of flow line nature. Applying the raw centre line data in a flow line model to conduct research into the mechanism behind Variegated Glacier's surge behaviour inevitably entails problems. In this study, the incomplete dataset is extrapolated into the upper and lower parts of the glacier. Furthermore, the centre line data are adapted to account for differences between width-averaged and centre line surface mass balance and ice thickness change, inflow from tributaries, and changes in surface width over time. The modifications to the dataset are backed-up by observations and clear, plausible physical explanations. Moreover, the revised dataset meets the imposed constraints regarding ice volume flux, specific mass balance and net volume change. Hence, the final dataset is considered a satisfying revision that makes the dataset more valuable for future research. Subsequent application of the revised dataset corroborates the idea that glacier evolution during quiescence is basically the growth back towards steady state after the glacier was brought out of balance by the preceding surge.
Highlights
Variegated Glacier is a surge-type glacier in Alaska, whose 20th-century surge history is well documented (Lawson, 1997; Eisen and others, 2001; Harrison and others, 2008)
The sudden change in water pressure accompanying surge initiation and propagation was ascribed to a switch from an efficient channel system during quiescence to an inefficient linked cavity system during surge, corroborating the theory proposed by Kamb and others (1985)
Applying a flow line model to Variegated Glacier to conduct research into its surge mechanism requires a dataset that accounts for lateral effects
Summary
Variegated Glacier is a surge-type glacier in Alaska, whose 20th-century surge history is well documented (Lawson, 1997; Eisen and others, 2001; Harrison and others, 2008). The sudden change in water pressure accompanying surge initiation and propagation was ascribed to a switch from an efficient channel system during quiescence to an inefficient linked cavity system during surge, corroborating the theory proposed by Kamb and others (1985). All these studies shed light on the mechanism behind Variegated Glacier’s surge behaviour. Subsequent application of the original as well as the revised dataset in a simple 1-D flow line model illustrates the effect of the performed data optimisation
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