Land boundary conditions from MODIS data and consequences for the albedo of a climate model

Abstract

This paper compares seasonal and spatial variations of MODIS albedos with those from the Community Land Model (CLM2). MODIS surface albedo data from September 2000 to August 2002 were used to investigate the model biases. To assess how inaccuracies in the land surface data used in CLM2 contribute to the model albedo biases, we created a new land surface dataset using the highest quality reprocessed MODIS products of leaf area index (LAI), plant functional type (PFT), and fraction of bare soil. A sensitivity experiment using this new data set quantifies the role of each variable and its contribution to the albedo biases. Our results indicate that most of the positive albedo biases result from an underestimation of LAI or an overestimation of the grass/crop fraction. Such biases can be largely reduced when the new data set is used. These results provide information on improving albedo in the model. This new land surface data set is available for use in CLM2.