Revised Simple Biosphere Model (SIB-2)
Encyclopedia
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
.
Simple Biosphere model
In climate modelling, the simple biosphere model is a model of the biosphere for use with atmospheric general circulation models that attempts to incorporate a biophysical realism in the formulation of the radiation balance and of energy at a level of appropriate sophistication to exist in the...
, whose model innovation is the use satellite images
Satellite imagery
Satellite imagery consists of photographs of Earth or other planets made by means of artificial satellites.- History :The first images from space were taken on sub-orbital flights. The U.S-launched V-2 flight on October 24, 1946 took one image every 1.5 seconds...
in global ambit, to obtain the vegetation phenology. Starting from these data of NDVI (normalized difference vegetation index
Normalized Difference Vegetation Index
The Normalized Difference Vegetation Index is a simple graphical indicator that can be used to analyze remote sensing measurements, typically but not necessarily from a space platform, and assess whether the target being observed contains live green vegetation or not.-Brief history:The exploration...
) 1° by 1°, obtained through the satellite AVHRR
Advanced Very High Resolution Radiometer
The Advanced Very High Resolution Radiometer is a space-borne sensor embarked on the National Oceanic and Atmospheric Administration family of polar orbiting platforms . AVHRR instruments measure the reflectance of the Earth in 5 relatively wide spectral bands...
(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
Photosynthetically active radiation
Photosynthetically active radiation, often abbreviated PAR, designates the spectral range of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis. This spectral region corresponds more or less with the range of light visible to...
absorbed by the green canopy (FPAR). With the obtaining of FPAR can be calculated LT (total leaf area index
Leaf Area Index
Leaf Area Index The Global Climate Observing System defines LAI as "one half the total green leaf area per unit groundsurface area. On sloping surfaces, the LAI should be projected to the normal to the slope. LAI is expressed in terms of square meters of leaf per square meter of ground...
) 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
Zenith
The zenith is an imaginary point directly "above" a particular location, on the imaginary celestial sphere. "Above" means in the vertical direction opposite to the apparent gravitational force at that location. The opposite direction, i.e...
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
Climate model
Climate models use quantitative methods to simulate the interactions of the atmosphere, oceans, land surface, and ice. They are used for a variety of purposes from study of the dynamics of the climate system to projections of future climate...
.