A Numerical Method of Inferring the Budget History of a Glacier from its Advance and Retreat

Abstract

AbstractThe paper considers how to calculate the budget history of a glacier from the historical record of its advance and retreat. The linearized differential equations developed in previous papers are used to compute a series of coefficientsg(n). Theg(n) operate directly on a record of annually spaced observations of the position of the glacier terminus, to give the time variation of net budget. Theg(n) are calculated for South Cascade Glacier, Washington, U.S.A. and for Storglaciären, Kebnekaise, Sweden, and are applied to the terminus records of these two glaciers. The results indicate that the figures for the retreat during individual years are not sufficiently reliable to deduce annual net budget changes with confidence. But the coarser features of the terminus records give net budget figures that agree well with the 9 yr. or 10 yr. means of recent observations. The theory extends the generalized budget record of Storglaciären back by several decades. and shows an increase in net budget in the 1930’s that is not immediately apparent in the terminus record.