Glacier mass-balance determination by remote sensing and high-resolution modelling

An indirect methodology for determining the distribution of mass balance at high spatial resolution using remote sensing and ice-flow modelling is pre sented. The method, based on the mass-continuity equation, requires two dat asets collected over the desired monitoring interval: (i) the spatial patte rn of glacier surface-elevation change, and (ii) the mass-flux divergence f ield. At Haut Glacier d'Arolla, Valais, Switzerland, the mass-balance distr ibution between September 1992 and September 1993 is calculated at 20 m res olution from the difference between the pattern of surface-elevation change derived from analytical photogrammetry and the mass-flux divergence field determined from three-dimensional, numerical flow modelling constrained by surface-velocity measurements. The resultant pattern of mass balance is alm ost totally negative, showing a strong dependence on elevation, but with la rge localized departures. The computed distribution of mass balance compare s well (R-2 = 0.91) With mass-balance measurements made at stakes installed along the glacier centre line over the same period. Despite the highly opt imized nature of the flow-modelling effort employed in this study, the good agreement indicates the potential this method has as a strategy for derivi ng high spatial and temporal-resolution estimates of mass balance.