Observation of the Argentìere Glacier Flow Variability from 2009 to 2011 by TerraSAR-X and GPS Displacement Measurements

International audience—In this paper, 3 years of surface displacement mea-surements obtained by space-borne synthetic aperture radar (SAR) observations are presented over theArgentì ere glacier in the Mont-Blanc massif, France. This temperate glacier is instru-mented by a network of four Global Positioning System (GPS) sta-tions used as ground truth. Thirty-eight pairs of descending and ascending high-resolution TerraSAR-X (TSX) acquisitions cov-ering the study region are used to derive displacement fields at 11-day intervals in spring and summer 2009 and summer 2011. The combination of ascending and descending pairs acquired over the same period allows 3-D displacement fields to be inverted. Our SAR analysis quantifies displacement rates from 10 cm/day at the altitude of 2600 m to 30 cm/day at the altitude of 1800 m. Time series of SAR displacement results are compared with in situ GPS measurements of a continuous station set up at the altitude of 2441 m. Both data sources present displacement of the same order of magnitude with an average value of 20 cm/day in 3-D and show intra-seasonal variabilities, with fast accelerations over short time intervals