Remote sensing of parameters that regulate energy and water transfer at the land-atmosphere interface

The exchange of energy and water between the land surface and the atmosphere is dominated by two parameters: the fractional green vegetation cover, and the wetness of the bare soil patches. An account is given of the way satellite remote sensing can be employed to infer these parameters, and of their integration into a land surface model to simulate the surface energy and water balance. Fractional green vegetation cover is obtained by means of the AVHRR Normalized Difference Vegetation Index, adopting a simple linear relation between this vegetation index and fractional green vegetation cover. Soil moisture is retrieved using the SSM/I Polarization Difference Temperature, employing the dependence of the dielectric constant of the soil on water content. A demonstration is given of the implementation of these two parameters in a land surface model, running the latter for the temperate grassland area of the FIFE held experiment for a two-week period in summer. A comparison with observations shows that the error on the simulated energetic fluxes is of the same order as the estimated experimental error of ground-based flux measurements. (C) 2000 Elsevier Science Ltd. All rights reserved.