Spectral Absorption of Solar Radiation in Alpine Snowfields

Abstract

We measured penetration of solar radiation into snow at various times of the year with a spectral radiometer. We found that light absorption obeys a y = axn law where n varies from 0.71 to 2.10. The absorption coefficient n decreases with increasing snow density. The 1% of surface value of total energy occurs at a snow depth of approximately 18 cm in winter, increasing to a maximum of 110 cm in late summer when snow density is near its maximum. Penetration of 0.1% of the surface radiation is shown to coincide with the approximate date and depth of snow pack for the first spring bloom of snow algae, implying that increasing light penetration may initiate germination of overwintering stages.