8.2 Globally Describing the Current Day Land Surface and Historical Land Cover Change in Ccsm 3.0 Using Avhrr and Modis Data at Fine Scales

Tian et al., (2004a), Oleson et al., (2003), and Tian et al., (2004b) recently identified significant differences between the current land surface parameters of the Community Land Model (CLM) used with the Community Climate System Model (CCSM), and global land surface descriptions from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite mapping. Specifically these investigations identified significant differences in Leaf Area Index (LAI), Fraction of Photosynthetically Active Radiation (FPAR), and land surface albedo. Tian et al., (2004a) suggested that these differences in land surface representation, especially land surface albedo, may significantly affect the accuracy of climate simulation of the CCSM model. To asses whether these differences in land surface representation do have significant impacts on the climate modeled in the CLM and the CCSM, new land surface parameters have been developed from land surface data derived from NOAA Pathfinder Advanced Very High Resolution Radiometer (AVHRR) and MODIS satellite data that minimise these differences. The impact on the climate simulated in the CCSM with these new parameters was assessed through a climate sensitivity experiment with the new parameters against a control experiment with the current land surface parameters. The climate modeled in these sensitivity experiments were compared with globally observed climate data to evaluate the climate impacts that the new land surface parameters had at global, continental and regional scales.