Prototyping of MISR LAI and FPAR algorithm with POLDER data over Africa

Abstract

The multi-angle imaging spectroradiometer (MISR) instrument is designed to provide global imagery at nine discrete viewing angles and four visible/near-infrared spectral bands. The MISR standard products include vegetation canopy green leaf area index (LAI) and fraction of photosynthetically active radiation absorbed by vegetation (FPAR). These products are produced using a peer-reviewed algorithm documented in the EOS-AM1 (Terra) special issue of the Journal of Geophysical Research. This paper presents results on spatial distributions of LAI and FPAR of vegetated land surfaces derived from the MISR LAI/FPAR algorithm with bidirectional reflectance data from the polarization and directionality of the Earth's reflectance (POLDER) instrument over Africa. The results indicate that the proposed algorithm reflects the physical relationships between surface reflectances and biophysical parameters and demonstrates the advantages of using multiangle data instead of single-angle data. A new method for evaluating bihemispherical reflectance (BHR) from multi-angle measurements of hemispherical directional reflectance factor (HDRF) was developed to prototype the algorithm with POLDER data. The accuracy of BHR evaluation and LAI/FPAR estimation is also presented. To authors demonstrate the advantages of using multi-angle data over single-angle data of surface reflectance.