Comparison between the results of a snow metamorphism model and remote sensing derived snow parameters in the Alps

The numerical snow metamorphism model CROCUS derives a complete description of the snow cover according to ifs geographical location (range), elevatio n, slope, and orientation. From the remote sensing data, snow parameters th at were comparable to the model results were derived: the lower elevation o f the snare cover, the surface grain size, and the surface temperature. The Landsat Thematic Mapper sensor teas used because it has a good spatial res olution, a short wave infrared channel which is sensitive to grain size, an d a thermal infrared channel. A first Landsat TM (Thematic Mapper) scene wa s acquired on 24 April 1992 and a second one on II December 1992. A DEM (di gital elevation model) was used to obtain the local incidence angles and th e elevation of each snow pixel. The pixels were then grouped according to t he CROCUS classification (range, elevation, slope, orientation), and the me an snore characteristics for each class were compared with the CROCUS resul ts. The lower limit of snow and the surface grain size derived from TM data compared favorably with the model results even if those parameters were no t always easy to define. Larger differences were found for the temperature because it caries rapidly and is very sensitive to shadowing by surrounding mountains and abo because ifs remote measurement is dependent on atmospher e conditions. (C) Elsevier Science Inc., 1999.