Estimation of surface snow properties using combined near-infrared reflectance and millimeter-wave backscatter

The need to estimate surface snow properties such as surface roughness, free-water content, and average grain size is crucial in determining the metamorphic state of snow for various military and environmental applications. Remote sensing techniques using combined concurrent measurements of near-infrared passive reflectance and millimeter-wave radar backscatter show promise in estimating the above snow parameters. Near-infrared reflectance is strongly dependent on snow grain size and free-water content, while millimeter-wave radar backscatter is primarily dependent on free-water content, and to some extent, on surface roughness. However, the spatial resolutions and penetration depths are different at near-infrared and millimeter wavelengths. By combining near-infrared and millimeter-wave measurements, the estimation of spatial variations in free-water content of snow can be improved considerably, while simultaneously providing meaningful estimates of grain size and surface roughness