Effects of Solar Zenith Angle on Forest Canopy Albedos Calculated with a Geometric-Optical Model
Abstract
The Bidirectional Reflectance Distribution Function (BRDF) provided by the Li-Strahler geometric-optical forest canopy model has been integrated to provide instaneous hemispherical reflectances of vegetated surfaces. Given the anisotropy of canopied surfaces, the sensitivity of these spectral albedos to the illumination angle of the sun was suspect and therefore required testing. A variety of simulated canopies (conifer, savanna and shrub) were modeled with varying solar angles. In all cases, the surface albedo gradually decreased with increasing solar zenith angle. Such sensitivity to solar position simplifies the realistic modeling of surface albedos for energy balance studies.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1992
- Accession Number
- ADA256680
Entities
People
- Alan H. Strahler
- Crystal B. Schaaf
- Xiaowen Ki
Organizations
- Phillips Laboratory