Reconstitution des fluctuations du bilan de masse du Glacier Blanc (Massif des Ecrins, France) entre 1985 et 2000, par télédétection optique (imagerie Spot et Landsat)

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We intented to reconstruct the mass balance fluctuation series of the Glacier Blanc for the 1985-2000 period, using satellite Optical Remote Sensing. We used the linear variation db/dz near the Equilibrium Line Altitude (ELA), which allows us to transform the ELA variations in a mass balance fluctuation, with satellite data recorded at the end of the hydrological year. This operative method enables to use satellite images and obtain mass balance variations on wide areas, especially where few direct mass balance measurements are available. This method was tested on the Glacier Blanc which has an adapted morphology to locate the ELA and a mass balance fluctuation close to the one of its neighbours Sarennes and Saint Sorlin glaciers (Grandes Rousses area). On the whole period, results are coherent since the mass balance fluctuation data calculated with this method are quite similar with those of the Grandes Rousses area glaciers, and vary in the same proportion. The main differences are due to the day of images acquisition.