A hyperspectral method for remotely sensing the grain size of snow

We have developed a robust, accurate inversion technique for estimating the grain size in a snowpack's surface layer from imaging spectrometer data. Using a radiative transfer mode, the method relates an ice absorption feature, centered at lambda =1.03 mum, to the optically equivalent snow grain size. Because the interpretation is based on the area-not depth-of the absorption feature scaled to absolute reflectance, the method is insensitive to instrument noise and does not require a topographic correction. We tested the method using Airborne Visible/Infrared Imaging Spectrometer data over the eastern Sierra Nevada, California, and we validated it with a combination of ground-based spectrometer data and grain size measurements. (C) Elsevier Science Inc., 2000.