Calibrating the Simple Biosphere Model for Amazonian Tropical Forest Using Field and Remote Sensing Data. Part I: Average Calibration with Field Data

This paper describes the operation and calibration of the simple biosphere model (SiB) of Sellers et al. using micrometeorological and hydrological measurements taken in and above tropical forest in the central Amazon basin. The paper provides: (i) an overview of the philosophy, structure and assumptions used in the model with particular reference to the tropical forest; (ii) a review of the experimental systems and procedures used to obtain the field data; and (iii) a specification of the physiological parameterization required in the model to provide an adequate average description of the data. In the course of this study, it was found that some of the existing literature on stomatal behavior for tropical tropical species is inconsistent with the observed behavior of the complete canopy in Amazonia and that the rainfall interception store of the canopy is considerably smaller than originally specified in SiB. Also the turbulent transfer model used in SiB was modified to account for the effects of height-varying foliage density. Finally, it was demonstrated that there is a distinct annual cycle in the biophysical properties of the forest canopy which influences the partitioning of energy into sensible and latent heat fluxes.