Approaches to Modelling the Surface Albedo of a High Arctic Glacier
Broadband surface albedo measurements, made during the summer melt season at three weather stations on John Evans Glacier (79°40 ′N, 74°00 ′W), varied strongly with the solar zenith angle (θz). Tests were carried out to assess the impact of diurnal variations in surface albedo on seasonal net shortwave radiation (K* ) totals. Removing the diurnal signal from albedo measurements by daily averaging of hourly measurements, or by applying midday measurements to all hours of the day, changed K* by up to 16%. Ignoring measurements made at θz & 75°, to account for measurement (cosine) error at high θz , decreased K* by between 5 and 18%. Given the sensitivity of K* to diurnal patterns in surface albedo, experiments were carried out with two albedo models. One model accounted for albedo variations with θz and one did not. The model driven by θz , when implemented within a surface energy balance model for John Evans Glacier, produced better melt estimates. This suggests that diurnal variations in surface albedo should be accounted for in energy balance models of glacier melt.
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Document Type: Research Article
Affiliations: Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Canada
Publication date: 1999-12-01