The GeoSail model: a simple addition to the SAIL model to describe discontinuous canopy reflectance

The scattering from arbitrarily inclined leaves (SAIL) model was combined w ith the Jasinski geometric model to simulate canopy spectral reflectance an d fraction of absorbed photosynthetically active radiation (f(APAR),) for d iscontinuous canopies. This model is called the GeoSail model. Tree shapes are described by cylinders or cones distributed over a plane. Spectral refl ectance and transmittance of trees are calculated from the SAIL model to de termine the reflectance of the three components of the geometric model: ill uminated canopy, illuminated background, and shadowed background. Although the GeoSail model is relatively simple, calculations of canopy reflectance and fraction of intercepted photosynthetically active radiation (F-IPAR) co mpared well with measurements collected in field experiments in forests in Minnesota and Oregon. (C) 2001 Elsevier Science Inc. All rights reserved.