NCEP-NCAR and ECMWF reanalysis surface water and energy budgets for the Mississippi River basin

Surface water and energy budgets from the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) and European Centre for Medium-Range Weather Forecasts (ECMWF) reanalyses are compared here with each other and with available observations over the Mississippi River basin, which is a focus of the Global Energy and Water Cycle Experiment Continental-Scale International Project. There are a number of noticeable differences and similarities in the large-scale basin averages. The NCEP-NCAR reanalysis seasonal precipitation and runoff are larger than the available observations; presumably, evaporation and surface water variations also are too large. The ECMWF reanalysis precipitation is much closer to the observations, whereas the corresponding surface runoff and seasonal surface water variations are too small. The NCEP-NCAR and ECMWF reanalysis seasonal energy components are more similar to each other. The NCEP-NCAR and ECMWF interannual variations also are comparable, indicating that these reanalyses probably can be used to begin to study interannual variations. Nonetheless, improved land surface parameterizations are needed to depict surface water and energy processes and, in particular, variations in seasonal surface water and runoff better.