Modelling vegetation angular signatures from DSCOVR/EPIC and MISR Observations

Abstract:

The angular signatures of reflectance are rich sources of diagnostic information about vegetation canopies, because the geometric structure and foliage optics determine their magnitude and angular distribution. This poster presents angular signatures of Bidirectional Reflectance Factors (BRF) in different biome types for the period of concurrent DSCOVR/EPIC (Earth Polychromatic Imaging Camera onboard the Deep Space Climate Observatory) and MISR (Terra Multi-angle Imaging SpectroRadiometer) observations. We developed a BRF model, which could approximate DSCOVR/EPIC and MISR observations, through analyses of variations in magnitude and shape of angular distribution of canopy reflected radiation and the rigorous use of radiative transfer theory. In this model, the correlation coefficient, visible fraction of leaf area in the direction Ω from the sunlit areas of leaves, is an important parameter that allows us to extend conventional radiative transfer equation to media with finite dimensional scatters and consequently accurately discriminate between sunlit and shaded leaves. Our model was able to capture seasonal variations of reflectance in amazon rain forest, which resulted from changes in both leaf area and solar zenith angle.