Modelling the water and energy balances of Amazonian rainforest and pasture using Anglo-Brazilian Amazonian climate observation study data

A soil-vegetation-atmosphere-transfer model, SWAPS, is introduced. The mode l is based on existing models for two-layer evaporation and energy balance, interception evaporation and unsaturated soil moisture transport. The mode l includes a physically based parameterisation for the soil surface resista nce to evaporation las well as a bio-physical vegetation surface resistance ). SWAPS is tested against long-term soil moisture data and shorter term fl ux data from three sites from the Anglo-Brazilian Amazonian Climate Observa tion Study. Two pasture sites with widely different soil hydraulic properti es, and a rainforest site have been used. Flux data are available at these sites under both wet and dry conditions. The model appears to perform well in reproducing the longer term soil moisture as well as surface fluxes. The interception loss for the forest site calculated over the long term agrees with other studies for the Amazonian forest. For the pasture sites the int erception loss is less than, but similar to, that of the forest. (C) 1999 E lsevier Science B.V. All rights reserved.