Sensitivity of the observed U.S. water budget to two different precipitation estimates

Water budgets derived from observations rely heavily on the quality of the radiosonde, river discharge and precipitation. We discuss differences in derived estimates of evaporation that result from application of daily raingage precipitation from two CPC datasets with different spatial resolutions. We analyze quantitative effects of using these precipitation datasets on area-averaged water budgets in the central United States. Preliminary analysis suggests significant differences between 25-year time series of derived evapotranspiration since this quantity is computed as the difference between precipitation and radiosonde based vapor flux convergence. This analysis motivates a discussion of uncertainties in the overall water budget in terms of uncertainties in the observations.