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Coupling of water vapor convergence, clouds, precipitation, and land-surface processes

On daily timescales, the climate over land is a complex balance of many coupled processes. ERA40 reanalysis data for subbasins of the Mississippi in summer are used to explore the links between these processes in a fully coupled model system, and observed surface precipitation and surface short-wave fluxes derived by the International Satellite Cloud Climatology Project are used for evaluation. This paper proposes that the effective cloud albedo viewed from the surface is a useful link which connects the cloud fields to both surface and large-scale processes. The reanalysis has a low bias in cloud albedo in all seasons except summer. In the coupled system in the warm season, on daily timescales, the lifting condensation level falls as soil moisture and precipitation increase. The ratio of the cloud short-wave radiative forcing at the surface to the diabatic precipitation heating of the atmosphere is less in the reanalysis than in the observations. The surface energy budget is split into the surface net radiation and the evaporative fraction. The surface cloud radiative forcing largely determines the surface net radiation, while evaporative fraction, with fixed vegetation, is largely determined by temperature and near-surface soil moisture.

ERA-40 Monthly river basin DATA: 1979-2002

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Betts, A. K. (2007), Coupling of water vapor convergence, clouds, precipitation, and land-surface processes, J. Geophys. Res., 112, D10108, doi:10.1029/2006JD008191.