Observations on the Relation of the Shortwave Reflectivity of Recently Deposited Snow to its Physical Properties

Abstract

The integrated albedo for solar radiation in the 0.4?0.7 ?m wavelength range was measured near noon over a wet snow cover before and after a new snowfall. Observed values were compared with those estimated from measurements of surface density, air permeability, and the total-to-diffuse-flux ratio by means of five models described in the literature and by using empirical correlations to estimate grain size. The models yield widely divergent results. The model with the best apparent performance shows an rms error of 0.02 with no particular bias. With one exception, however, the remaining models yield over-estimates. Albedos calculated from samples taken from differing surface layers and variation of the prediction errors with the snow accumulation pattern were compared. Results suggest that a major source of error is the large depth interval sampled by the surface layer measurement technique as compared with the thickness of the surface layer of snow in which the bulk of absorption and scattering occur.