Glacier mass balance determination by remote sensing in the French Alps: progress and limitation for time series monitoring

This paper presents an approach founded on an indirect methodology to determine the distribution of mass balance at high spatial resolution using remote sensing and ground stakes measurements. A recent time series of images from optical and SAR data are selected on 3 outlet glaciers well suited in the French Alps to evaluate the accuracy of the computed mass balance. The method is based on the snowline determination as a proxy of the equilibrium line altitude (ELA). The key of the transfer is the activity coefficient (db/dz) for the annual mass balance calculation. Comparison between measured and computed mass balance provide a good correspondence (R²=0.90) and allows extending the method on large-scale areas. The limitations are cloudiness for optical data and high slope distortion on SAR images.