Koster et al. 2001
Koster, R.D., P.A. Dirmeyer, P.C.D. Milly, and, 2001: Comparing GCM-generated land surface waster budgets using a simple common framework. In Land Surface Hydrology, Meteorology, and Climate: Observations and Modeling. V. Lakshmi, J. Albertson, and J. Schaake, Eds., Water Sciences and Application, vol. 3. American Geophysical Union, 95-105.
Multi-decade climate simulations with four atmospheric general circulation models (GCMs) are analyzed to determine the extent to which the precipitation and net radiation forcing simulated by each model determines the simulated annual surface water budget in a given region. The success of two simple climatological relations in characterizing the mean and interannual variability of each GCM's surface water budget implies that the forcing does indeed impose a primary control. Intermodel differences in the forcing are found to be strongly related to intermodel differences in the normalized surface fluxes (i.e., the mean and variability of the annual evaporation and runoff normalized by annual precipitation), with the forcing differences explaining roughly half the variance in the normalized flux differences. The results imply that to understand the annual evaporation and runoff fluxes simulated by a GCM in a given region, a study of the forcing and its relationship to both the large-scale circulation and the land surface itself is at least as relevant as a focused analysis of the evaporation and runoff parameterization used by the land surface scheme.