Application to the Airborne Multi-Spectral Scanner (AMSS) Observation in 1998 of the Vegetation and Snow Indices, Based on the Spectral Reflectance Characteristic

Abstract

Using the Airborne Multi-spectrum Scanner in 1998, snow and vegetation indices, with which (1) drop of the radiance between visible and near infrared over snow cover and (2) immediately increase on a shorter near infrared wavelength over vegetation covers (forest etc.) were considered, were evaluated.
Compared with the two wavelength band indices (same as NDVI etc.), the index which reflected the effect of (1) and (2) was sensitive to the vegetation density (Plant Area Index; PAI) under the coexistence of both vegetation and snow, and could recognize the state of the vegetation cover independent on the snow cover on the floor.
Moreover, it was confirmed that the reflectivity spectrum in the shorter wavelength than 0.9μ m could catch the steep rise made by vegetation properties around the value of 0.7μ m.
In addition, the snow cover and the forest region were classified by using S3, with which PAI under coexistence of both vegetation and snow can be estimated, and how the reflectivity spectrum of several channels changed according to the observation angle was estimated. Fore scattering was strong over the snow cover and Lambert-like scattering was found in the forest region. Bi-directional reflectance distribution function (BRDF) characteristic appears strongly, though the variation of viewing angle is small (±35degrees). However, BRDF of each wavelength is similar, and its influence on the index is small.