Derivation of Leaf Clumping Index Using MODIS/MISR Data with BRDF Models
Lihong
Su, Department of Geograpy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, sul@email.unc.edu
(Presenting)
Conghe
Song, Department of Geography, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, csong@email.unc.edu
Solar radiation intercepted leaves in vegetation canopies is the ultimate driving force for ecosystem processes of carbon and water cycling. The amount of solar radiation intercepted by vegetation canopies is determined by two factors, leaf area index (LAI) and the organization of leaves in the canopy. Tremendous efforts have been dedicated to estimating LAI with remotely sensed images, but scientists usually have to assume uniform spatial arrangment of leaves in the canopy when modeling canopy interception of radiation. The spatial arrangement of leaves in the real world can significantly different from a uniform distribution which would cause serious errors in model results on carbon assimilation and transpiration. In this study we investigated using data from Multi-angle Imaging SpectroRadiometer (MISR) and Moderate Resolution Imaging Spectroradiometer (MODIS) observations provide a means to characterize the anisotropy of surface reflectance, which has been shown to contain information on the structure of vegetated surfaces. We found that it is a feasible to estimate leaf clumping index using MISR and MODIS BRDF model parameter products. The semi-physical Ross-Thick-Li-Sparse reciprocal model shows slightly better performance than the pure mathematical RPV model. Validation of the leaf clumping index is a major challenge.
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