A global vegetation index for SeaWiFS: Design and applications

Optimized vegetation indices provide a convenient approach to estimate crucial plant properties on the basis of satellite data. This paper describes the steps followed to implement an index optimized to estimate the Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) on the basis of data generated by the SeaWiFS instrument, and the preliminary results obtained. Index values are computed on the basis of top of atmosphere bidirectional reflectance factor values in the blue, red and near-infrared domains, as well as information on the geometry of illumination and observation. Results obtained with SeaWiFS data are used to evaluate the performance of the index. This case study documents the ability of the index to discriminate between various surface types, and its insensitivity to changes in the geometrical conditions of observation and to atmospheric effects. The operational environment set up at SAI to process SeaWiFS data is outlined and selected standard retrievals resulting from a monthly composite analysis are shown as examples of the products generated.