Sensitivity of a land surface parameterization scheme to the choice of remotely-sensed landcover data sets

The characteristics of satellite-derived landcover data for climate models vary depending on sensor properties and processing options. To better understand the first order effects of differences in landcover data on a land surface parameterization scheme (VBATS), stand-alone model runs were performed for two adjacent 2.8° by 2.8° GCM gridcells in Wyoming using landcover from two satellite-derived maps (AVHRR, TM) and a global landcover data set commonly used in GCMs. Substantial differences in prescribed landcover were found between the three datasets. Despite these differences, the VBATS simulated surface fluxes were similar in the eastern gridcell for the two satellite data sets. In the western gridcell, the partitioning of net radiation into sensible and latent heat fluxes was affected by the relative proportions of wet cover types (i.e., inland water and irrigated crop) prescribed by the two satellite data sets. This emphasizes the importance of accurately estimating the proportion of wet cover types within a GCM gridcell in arid regions.