An understanding of the relationship between the atmosphere and the land surface requires detailed information about the physical characteristics of the vegetation that covers the area of interest. These characteristics include canopy density, percent vegetation cover, and green canopy fraction. We have used measurements of these variables from two sources in off-line runs of the Simplified Simple Biosphere Model (SSiB) for several regions of sub-Saharan Africa. The first source was estimates for broad land cover types, mostly obtained from point field measurements. The second source was satellite data processed using a variety of algorithms. The results indicate that i) correlations between model inputs and outputs conform to expected relationships; ii) land cover variability within cover classes significantly affects surface fluxes; iii) satellite instrument measurements of land surface variables are more realistic representations of surface conditions than are the available point field measurements; and iv) spatially aggregated model input data produce acceptable results under many circumstances.