A Comparison of the Energy-Balance and Bulk-aerodynamic Approaches for Estimating Glacier Melt

Abstract

Two models that estimate glacier ablation from simple meteorological observations are described. Both the energy-balance and bulk-aerodynamic approaches are used to determine the bulk-exchange coefficient for transfer of sensible- and latent-heat energy to the melting ice surface from 17 summer days of measurement on Ivory Glacier, New Zealand. The behaviour of the coefficient is examined over progressively increasing time intervals and as a function of wind speed and gradient, and of atmospheric stability. The models are verified with 36 d of independent data from a different summer on the same glacier. The more accurate short-term estimates of ablation are obtained using the energy-balance approach with empirically but independently derived values of the exchange coefficient.