The Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) quantifies the fraction of the solar radiation absorbed by live leaves for the photosynthesis activity. It refers only to the green and alive elements of the canopy and hence can be taken as one of the measures of canopy health status. It is one of the surface parameters that can be used in quantifying CO2 assimilation by plants and the release of water through evapotranspiration. The FAPAR depends on the canopy structure, vegetation element optical properties, atmospheric conditions, and angular configuration. To overcome this latter dependency, a daily integrated FAPAR value is assessed.
Top of canopy input reflectances from SPOT-4 & -5 and - more recently - PROBA-V in red, near infrared and shortwave infrared bands, normalized over a period of 30 days are used in a neural network approach. Normalization over the 30-day period us done with a weighting function which favours the most recent daily observations of the compositing period. The neural network is trained with true (non-simulated) reflectance data and FAPAR estimates from fused existing products based on MODIS and CYCLOPES FAPAR products.
For more information we refer to the ATBDs mentioned in the references section.
This is version 2 of this data set provided by COPERNICUS Global Land Service.
Data were downloaded in netCDF file format with 1/112° grid resolution and global coverage. This data are available from ICDC on request. For the main data set offered here, we block-averaged the data onto a 0.5° x 0.5° plate carree grid. Data are available for the latitude range 70°S to 80°N. Note, however, that limited solar illumination reduces the maximum northern latitude to smaller values during winter.
Last update of this data set at ICDC: August 30, 2019.