Land surface processes over GCIP Large Scale Areas

The GEWEX Continental-scale International Project (GCIP) aims at the development and evaluation of coupled hydrologic/atmospheric models covering the Mississippi River basin. Within this context, the surface energy budgets from three operational mesoscale models and from the NCEP/NCAR Reanalysis are evaluated against information derived from high-resolution satellite measurements. The three mesoscale models are: 1) the NCEP Eta model, 2) the Mesoscale Analysis and Prediction System (MAPS) model, and 3) the Global Environmental Multiscale (GEM) model. The focus of this research is in GCIP's Large Scale Areas, which roughly cover the four main subbasins of the Mississippi. Local evaluation of radiation terms and latent and sensible heat fluxes is performed with measurements obtained from the Atmospheric Radiation Measurement Program site in the southern Great Plains.

Of particular interest is to estimate the biases found in all models with respect to "observed" surface radiative fluxes, and to examine the nature of energy partitioning between sensible and latent heat fluxes, in terms of the Bowen Ratio. Addressed will be plausible causes of the differences and needs for corrections. Earlier results suggest that the downward short wave radiation estimated from the GEM model has the least bias when compared to satellite estimates, but all models have difficulties representing the Bowen ratio, particularly during winter.