Scaling estimates of vegetation structure in Amazonian tropical forests using multi-angle MODIS observations

•Multi-angle MODIS observations were used to characterize anisotropy of tropical vegetation.•MODIS anisotropy is strongly correlated to canopy entropy from LiDAR, GLAS and QuikSCAT.•Multi-angle MODIS data can be used to scale estimates of vegetation structure in tropics. Detailed knowledge of vegetation structure is required for accurate modelling of terrestrial ecosystems, but direct measurements of the three dimensional distribution of canopy elements, for instance from LiDAR, are not widely available. We investigate the potential for modelling vegetation roughness, a key parameter for climatological models, from directional scattering of visible and near-infrared (NIR) reflectance acquired from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS). We compare our estimates across different tropical forest types to independent measures obtained from: (1) airborne laser scanning (ALS), (2) spaceborne Geoscience Laser Altimeter System (GLAS)/ICESat, and (3) the spaceborne SeaWinds/QSCAT. Our results showed linear correlation between MODIS-derived anisotropy to ALS-derived entropy (r2=0.54, RMSE=0.11), even in high biomass regions. Significant relationships were also obtained between MODIS-derived anisotropy and GLAS-derived entropy (0.52≤r2≤0.61; p