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Title: Variation in visual and near-infrared contrast with a snow background
Authors: United States. Air Force. Electronic Security and Communications Center for Excellence.
Peck, Lindamae.
Keywords: Grass albedo
Near-infrared concealment
Near-infrared contrast
Near infrared spectroscopy
Constrast sensitivity (vision)
Snow albedo
Snow surface
Visual concealment
Visual contrast
Wiscombe-Warren model
Publisher: Cold Regions Research and Engineering Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Special Report
Abstract: Visual and near-infrared concealment against a snow cover are considered in terms of the daily and longer-term variation in albedo of a shallow (<26 cm) snow cover. Examples of albedo of a Vermont snow cover demonstrate the influence of time of day (solar angle), incident solar radiation, snow depth, and snow wetness. Most albedos fell within the range 0.75-0.98. The most consistent variation was a decrease in albedo during the morning as the sun angle increased and a corresponding increase with decreasing sun angle in the afternoon. Albedo was low when the snow surface temperature indicated melting was occurring or when an increase in temperature ofthe soil beneath the snow cover indicated solar radiation was being absorbed by the soil. Examples of the diurnal variation in sun angle and the seasonal variation in maximum potential solar radiation, as calculated from site latitude and longitude and calendar date, are presented.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Special Report

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