Assessment of the accuracy of snow surface direct beam spectral albedo under a variety of overcast skies derived by a reciprocal approach through radiative transfer simulation

摘要

With radiative transfer simulations it is suggested that stable estimates of the highly anisotropic direct beam spectral albedo of snow surface can be derived reciprocally under a variety of overcast skies. An accuracy of ±0.008 is achieved over a solar zenith angle range of θ_(0)≤74° for visible wavelengths and up to θ_(0) ≤63° at the near-infrared wavelength λ=862 nm. This new method helps expand the database of snow surface albedo for the polar regions where direct measurement of clear-sky surface albedo is limited to large θ_(0)'s only. The enhancement will assist in the validation of snow surface albedo models and improve the representation of polar surface albedo in global circulation models.