Schematic representation of radiative flux components in the simple model. Solid lines with arrows represent the direct solar flux component at elevation angle dashed lines represent diffuse flux components over a bare soil fraction (right side) and a vegetated fraction (Fr; left side). Fluxes are represented by the symbol F with subscripts denoting various flux components either absorbed in the atmosphere, absorbed at the ground or within the vegetation canopy, scattered
upward or downward, or reflected upward. (Al1 absorbed fluxes are underlined.) The flux to space measured by a satellite radiometer is indicated by the dashed line labeled F_out (see Appendix).