Estimation of vegetation canopy leaf area index and fraction of photosynthetically active radiation absorbed by vegetation from remotely sensed multi-angle and multi-spectral data

Large scale ecosystem models require estimates of vegetation canopy leaf area index (LAI) and the fraction of photosynthetically active radiation absorbed by the green leaves (FPAR) in order to simulate the energy, heat and mass (water, carbon, etc) budgets. These variables can be obtained globally and operationally from satellite measurements of reflected solar radiation. While much work on forward modeling of vegetation reflectance has been done, it is only recently, in the context of new satellite sensors such as MODIS (moderate resolution imaging spectroradiometer), MISR (multi-angle imaging spectroradiometer), POLDER (Polarization and Directionality of the Earth´s Reflectance), etc., that attention has focused on the inverse problem; that is, estimating LAI (and FPAR) from remote reflectance measurements. This article provides some results on global LAI and FAPAR fields derived from current satellite sensor data