Browsing by Autor "J.-P. Dedieu"

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    Glacier mass balance determination by remote sensing in the French Alps: progress and limitation for time series monitoring
    (2004) J.-P. Dedieu; Antoine Rabatel; Christian Vincent; François Valla; Emmanuel Thibert; Yves Arnaud
    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 (R/sup 2/=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.
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    Glacier mass balance reconstruction by remote sensing in the French alps : comparison with ground measurements
    (2004) J.-P. Dedieu; Antoine Rabatel; Christian Vincent; Álvaro Soruco
    The Alpine glaciers are sensitive to climate fluctuation, and glacier mass balance may be used as a proxy indicator of the regional climate change impacts. An indirect methodology is presented for determining the distribution of mass balance at high spatial resolution using remote sensing and ground stakes measurements. The method is based on the snowline determination as a proxy of the equilibrium line altitude (ELA) and the key of the transfer is the activity coefficient (db/dz) for the annual mass balance calculation. Three outlet glaciers well suited in the French Alps (ground stakes) were selected to evaluate the accuracy of the method for a short period (7 cycles) and extended for a longest period (15 cycles) for a glacier with limited ground measurements. The computed distribution of mass-balance compares well (R/sup 2/ = 0.90) with mass-balance measurements made at stakes installed along the glacier centre line for the short period.