Remote Sensing of Snow in the Solar Spectrum:  Experiments in the French Alps.

M. Fily; J.P. Dedieu; Y. Durand; C. Sergent

doi:10.14429/dsj.50.3434

M. Fily Laboratoire de Glaciologie et Geophysique de l'Environnement, CNRS/UJF, Grenoble.
J.P. Dedieu Laboratoire de la Montague Alpine, CNRS/UJF, Grenoble, France.
Y. Durand Centre d' Etudes de la Neige, Meteo-France, Grenoble, France.
C. Sergent Centre d' Etudes de la Neige, Meteo-France, Grenoble, France.

DOI: https://doi.org/10.14429/dsj.50.3434

Keywords: Snow metamorphism model, Landsat thematic mapper, CROCUS classification

Abstract

Two experiments were perfonned irliApril and December 1992 in the French Alps using simultaneous relnote sensing and ground truth data. Snow grain site and soot content of samples collected in the
field were measured. The Landsat thematic mapper (TM) sensor was used because it has a good spatial resolution, a middle infrared channel which is sensitive to grain size and a thermal infrared
channel. Firstj the reflectance data were compared with the theoretical results obtained from a bidirectional reflectance model. Then, some remote sehstng-derived snow parameters wbre compared
iWith the outpllt ofa snow metamorphism model (CROCUS),viz., lower elevation of the snowcover, lhe surface grl1in size and the surface temperature. A digital elevation model was used to obtain the
local incidenc:f angles and the elevation of each snow pixel. The pixels were then grouped according to CROCUS classification (range, elevation, slope, and orientation) and the mean snow chart;cheracteristics
for each class were .compared with the tROCUS results. The lower limit of snow and the surface grain size derived from TM data were compared favourably with the model results. Larger differences were
found for the temperature, because it varies rapidly and is very sensitive to shadowing by the snrrounding mountains and also because its remote measurement is dependent on atmospheric conditions.

Author Biographies

M. Fily, Laboratoire de Glaciologie et Geophysique de l'Environnement, CNRS/UJF, Grenoble.

Mr Fily isl teaching at University joseph Fourier of Grenoble in the field of Physics and Geophysics. He is the In-Charge of the Remote Sensing Group at the Laboratoire de Glaciologie and Geophysique de 1' Environmentn His areas of research intlude: antarctic ice sheet (solar spectrum and microwave remote sensing).

J.P. Dedieu, Laboratoire de la Montague Alpine, CNRS/UJF, Grenoble, France.

Mr JP Dedieu is working as Research Scientist at the Laboratoire de la Montagne Alpine, Grenoble His areas oflresearch include: remote sensing in the Alps for hydrological applications with active remote sensing sensors.

Y. Durand, Centre d' Etudes de la Neige, Meteo-France, Grenoble, France.

Mr Durahd is working as Research Scientist at the Centre d' Etudes de la Neige , a research institute of the' French Meteorological Institute. His areas of research include: atmospheric modelling and avalanche forecasting .

C. Sergent, Centre d' Etudes de la Neige, Meteo-France, Grenoble, France.

Mr Sergent is working as Research Enginere at the Centre d' Etudes de la Neige at Grenoble. His areas of work include:measurements of snow reflectance and avalanche forecasting.

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