Modelling glacier response to measured mass-balance forcing

Measurements of summer and winter mass balances have been carried out over the past 53 years on Storglaciaren, northern Sweden. Repeated surveys of the glacier have resulted in several maps of surface topography, as well as a map of the bed topography. A new time-dependent ice flow model allows us to compare the observed surface evolution of the glacier with that computed by the model using measured mass-balance maps as input. The computed volume change compares well with the measured change: the model replicates the distribution of surface elevation to within +/-10 m over 30 years of integration. On the model side, these deviations can be attributed to the low-resolution discretization of the model domain as well as to the limited accuracy of the ice rheology and omitted basal sliding. On the other hand, the uncertainties of the topography and mass-balance maps match the model uncertainties. In this sense, the experiments are a validation of both model and observations.