Surface Water and Energy Budgets for the Mississippi River Basin In Three NCEP Analyses

With recent developments in observation technology and advances in model physics, to provide more accurate representations of the earth system states, tremendous effort has been put into the NCEP Climate Forecast System Reanalysis (CFSR) project. The NCEP CFSR is a combination of global data assimilation and an advanced climate forecast system. Compared to the past global and regional reanalysis, the new system includes not only recent advances in atmospheric physics and ocean modeling techniques, but also features updates in the land surface model (Noah) and its companion data assimilation system (GLDAS). Focusing on the land component of CFSR reanalysis, this work provides an overview of its surface energy and water budgets with explicit comparisons to the previous EMC's North American Regional Reanalysis (NARR) and the NCEP Global Reanalysis II (GR2) and to available observations over the Mississippi basin with respect to their seasonal cycles and anomalies over a 31-year period (1979-2009). Comparisons of the basin average surface water and energy budget terms show that there are a number of noticeable differences. The GR2 seasonal precipitation and runoff are larger than the available observation; presumably, evaporation is large too. The CFSR and NARR precipitation (possibly evaporation) are much closer to the observation, whereas the corresponding runoffs are relatively small. The seasonal energy components are more similar to each other and the interannual variations are also comparable. The study shows that the high quality of the CFSR can be used to study interannual variations and climate changes.