Tussock Tundra Albedos on the North Slope of Alaska: Effects of Illumination, Vegetation Composition, and Dust Deposition

Abstract

The albedo of tussock tundra was measured at two sites on the north slope of Alaska. One site was selected because of its apparent uniformity and undisturbed condition, while the other site had been visibly affected by dust deposition from the Dalton Highway. Albedo measurements were made under varying cloud-cover conditions. It was hypothesized that observed variations in albedo at the undisturbed site were caused by variations in illumination conditions and ventilation cover type. A simple cloud index (CI) was used to characterize the cloud-cover-illumination conditions, and vegetation cover was described using a hierarchical classification scheme and point-guadrat sampling. Albedo at the undisturbed site was found to be related significantly to variations in CI but unaffected by differences in vegetation cover type. The final component of the study compared the albedo-CI relationships at the undisturbed and dust-impacted sites. It was concluded that dust deposition had a significant direct and/or indirect effect on the albedos at this site, particularly under cloudy conditions.