Diurnal asymmetry in surface albedo

Observed surface albedos do not always exhibit the classical diurnal symmetry associated with the diurnal variation of zenith angle, Morning/afternoon albedo differences observed in even vegetated terrain are found to range on the daily average from 0.01 to 0.05 in magnitude in this study, and they have been found to be as high as 0.1 at a given solar zenith angle in other studies, which influence both reflected and absorbed solar radiation during the course of a day. This diurnal asymmetry in albedo may be explained by the prevailing wind direction, which causes the canopy to lean. The albedo asymmetry also is simulated, taking into account the canopy reclination angle and direction. (C) 1998 Elsevier Science B.V. All rights reserved.