Hydrologic models increasingly require knowledge of the amount of snow cover within a pixel in order to provide accurate estimates of snow covered area. Present methods for remote sensing of subpixel snow cover require knowledge of the spectral reflectance properties of the snow as well as the background material, making these methods difficult to apply globally. Similar problems were encountered in global remote sensing of aerosol particles over varying land terrain. Since both aerosol and snow are dark at 2.1 ¿m, we suggest a method for sub-pixel snow mapping based on experience with remote sensing of aerosols. Here the pixel reflectance at 2.1 ¿m is used to estimate the reflectance of the non-snow regions in the pixel at 0.66 ¿m. The difference between the total pixel brightness at 0.66 ¿m and the derived brightness of the same pixel without the snow is used to estimate the sub-pixel snow cover with an error usually < ¿0.05.