Development of a satellite remote sensing technique for the study of alpine glaciers

This paper presents an experiment in MSS image interpretation for the systematic observation of glacier surfaces in the Alps. The glacier monitoring potential of visible and near-infrared data is applied here to the surveying of mountain glaciers, characterized by small areas and strong shading because of their typical morphology. The method developed identifies glacier surfaces by evaluating the intensity values of visible images combined with clearness conditions related to exposure, slope and the surface homogeneity of the glacier. Conditions of clarity, in the absence of a digital terrain model, are estimated from the number of saturated pixels in the visible bands. At a higher level, the near-infrared data used to identify snow and ice surfaces inside the glacier boundaries. The paper discusses the performance of the technique developed, as applied to the analysis of a temporal series concerning a group of 11 small glaciers with critical exposure conditions. The results are expressed as areas of glacier and snow-covered terrain in different years, thus enabling trends in regional mass balance to be estimated.