North American water and energy cycles

[1] Closure of the water and energy cycles for North Amer-ica has been improved by combining several new data sets to provide an integrated view from 1979 to 2010. We use new global atmospheric reanalyses, top-of-atmosphere radiation, surface fluxes including evaporation E and precipitation P, streamflow and river discharge, and Gravity Recovery and Climate Experiment estimates of water storage and its ten-dency. The atmospheric moisture budget provides more reliable estimates and reproducible time series of E-P than separate estimates of E and P. The excess of P over E is greatest in winter largely because of changing evapotrans-piration, whereas precipitation is largest in summer. The annual mean loss of energy to space of 33Wm-2 is compen-sated for nearly equally by transports of dry static energy and latent energy onto land. The annual cycle (amplitude of ~20Wm-2) of implied downward surface flux corresponds to changes in surface and soil temperatures and seasonal snowmelt