Field spectral signatures of snow, ice, and water

Abstract

Spectra were taken that describes free water, ice, and snow, and vegetation and inorganic backgrounds. The reflectance of water films, ranging from 0.008 to 5.35 mm, on a spectralon background varied with water depth and the water transmittance and absorbtance properties. Thin water films, > 3.5 mm, quenched the short wave infrared (SWIR) reflectance, even though moderate visible-near infrared reflectance occurred from the water-spectralon surfaces. Ice and snow have a similar number of absorption bands as water but their absorption maxima varied from those of water. River float-ice and glacial ice have diagnostic absorption features at 1.02 and 1.25 μm and negligible reflectance in the > 1.33 μm region. New powder snow, new wet snow, and older deep snow packs have similar shaped reflectance spectra. Thin snow accumulations readily masked the underlying surfaces. These snow pack surfaces have a small asymmetric absorption features at 0.90 μm and strong asymmetric absorption features at 1.02, 1.25, and 1.50 μm. These snow packs have measurable SWIR reflectance. An avalanche snow pack had low SWIR reflectance, which was similar to ice spectra. Water, ice and snow and ice surfaces have spectrally distinct features, which differentiates them and the background surfaces.