Radiative Transfer in Shrub Savanna Sites in Niger: Preliminary Results fromHAPEX-SAHEL. Part 3: Optical Dynamics and Vegetation Index Sensitivity to Biomass and Plant Cover

摘要

A shrub savannah landscape in Niger was optically characterized utilizing blue,green, red and near-infrared wavelengths. Selected vegetation indices were evaluated for their performance and sensitivity to describe the complex Sahelian soil/vegetation canopies. Bidirectional reflectance factors (BRF) of plants and soils were measured at several view angles, and used as input to various vegetation indices. Both soil and vegetation targets had strong anisotropic reflectance properties, rendering all vegetation index responses to be a direct function of sun and view geometry.