1. Scaling estimates of vegetation structure in Amazonian tropical forests using multi-angle MODIS observations
- Author
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Mendes de Moura, Yhasmin, Hilker, Thomas, Goncalves, Fabio G, Galvão, Lenio, dos Santos, João Roberto, Lyapustin, Alexei I, Maeda, Eduardo E, Arai, Egidio, and Valéria de Jesus Silva, Camilla
- Subjects
Canopy ,Global and Planetary Change ,010504 meteorology & atmospheric sciences ,Mean squared error ,Amazonian ,0211 other engineering and technologies ,02 engineering and technology ,15. Life on land ,Management, Monitoring, Policy and Law ,Atmospheric sciences ,01 natural sciences ,Article ,Geography ,Lidar ,13. Climate action ,Terrestrial ecosystem ,Moderate-resolution imaging spectroradiometer ,Altimeter ,Computers in Earth Sciences ,Anisotropy ,021101 geological & geomatics engineering ,0105 earth and related environmental sciences ,Earth-Surface Processes ,Remote sensing - Abstract
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 (r(exp 2)= 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 less than or equal to r(exp 2) less than or equal to 0.61; p less than 0.05), with similar slopes and offsets found throughout the season, and RMSE between 0.26 and 0.30 (units of entropy). The relationships between the MODIS-derived anisotropy and backscattering measurements (sigma(sup 0)) from SeaWinds/QuikSCAT presented an r(exp 2) of 0.59 and a RMSE of 0.11. We conclude that multi-angular MODIS observations are suitable to extrapolate measures of canopy entropy across different forest types, providing additional estimates of vegetation structure in the Amazon.
- Published
- 2018