Revised Simple Biosphere Model (SIB-2)

The model SIB-2 built by Sellers et al. (1996b) it is improvement of the model Sib-1, whose model innovation is the use satellite images in global ambit, to obtain the vegetation phenology. Starting from these data of NDVI (normalized difference vegetation index) 1° by 1°, obtained through the satellite AVHRR (Advanced Very High Resolution Radiometer), some simple corrections were applied, resulting in a product called FASIR-NDVI. This product is combined with the soil covering classification to obtain the global monthly fields, time-varying, of fraction of photosynthetically active radiation absorbed by the green canopy (FPAR). With the obtaining of FPAR can be calculated LT (total leaf area index) and N (canopy greenness fraction). These two fields (LT and N) are used to calculate the surface reflectances or albedo (aΛμ) and the roughness lengths (z0). FPAR is still directly used to calculate canopy photosynthesis (Ac) and conductance (gc). Some adjusted are applied in the data FASIR-NDVI, to that can be used in the calculation of the dependent parameters of these data: (I) Fourier wave adjustment; (II) Solar zenith angle adjustment; (III) Interpolation of missing data and (IV) Reconstruction of NDVI data classified as tropical evergreen broadleaf. In the SIB-2, there is not available a group of extensive spatial data for validation of the data derived by that methodology. The most important in this model, it has become possible to address realistically the spatial and temporal variability of land-surface parameters within a climate model.

References

• Sellers, J. P., D.A. Randell, G.J. Collatz, J.A. Berry, C.B. Field, D.A. Dazlich, C. Zhang, G.D. Collelo and L. Bounua, 1996. A revised land surface parametrization (SiB 2) for atmospheric GCMs. Part I:Model formulation, J. Climate, 9, 676-705.
• Sellers, J. P., S.O. Los, C.J. Tucker, C.O. Justice, D.A. Dazlich, G.J. Collatz and D.A. Randell, 1996. A revised land surface parametrization (SiB 2) for atmospheric GCMs. Part II: The generation of global fields of terrestrial biphysical parameters from satellite data, J. Climate, 9, 706-737.