NOAA-6 and 7 AVHRR visible (VIS) and near-infrared (NIR) radiance data from the advanced very high resolution radiometer (AVHRR) on board the National Oceanic and Atmospheric Administration's (NOAA) NOAA-6, 7 and 8 satellites were simulated for a black target, for bare soil and for tow, medium and high levels of green-leaf biomass. Simulations were based on measured reflectance and Dave's atmospheric models. Radiance data were generated for viewing and illumination geometry corresponding to the summer solstice, equinox and winter solstice at a latitude of 30°. The results indicate that the radiance responses to atmosphere are less for NOAA-7 geometry than for NOAA-6 and 8. Viewing in the backscatter direction has a more constant radiance response with increasing scan angle than viewing in the forward scatter direction. These results arc discussed with respect to atmospheric composition, surface reflectance and wavelength.