Comparison of in situ and Landsat Thematic Mapper derived snow grain characteristics in the alps
✍ Scribed by M. Fily; B. Bourdelles; J.P. Dedieu; C. Sergent
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 775 KB
- Volume
- 59
- Category
- Article
- ISSN
- 0034-4257
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✦ Synopsis
Two experiments were perfor~ned in April and December 1992 in the French Alps, using simultaneous remote sensing and ground truth data at 11 different locations. The snow grain .size and soot content were measured from samples collected in the fiel t. The snow reflectance was computed from Landsat Thermatic Mapper (TM) data with and without atmospheric correction. Then the data were compared with theoretical res'ults obtained from a bidirectional reflectance model. Most visible-channel signal's are affected by the pollutants in the .snow. The near-iterated channel signal,s are dependent on the grain .size. For the near infrared channel TM4, the optical grain size is close to the measured one, but the Landsatderived snow reflectance is not accurate enough to allow an invension of the grain .size from the reflectance. For the middle infrared channel's TM5 and TMT, the computed optical grain size is verdi different from the measured one, but a linear relation was fimnd between those different sizes for April and December data in spite of the very different .solar irradiance conditions. Using ratios between channel's instead of a single channel gives only a qualitative estimate of the grain size. ©Elsevier Science Inc., 1997