|Title||Large area mapping of southwestern forest crown cover, canopy height, and biomass using MISR|
|Publication Type||Journal Article|
|Year of Publication||2008|
|Authors||Chopping, M, Moisen, G, Su, L, Laliberte, A, Rango, A, Martonchik, J, Peters, DC|
A rapid canopy reflectance model inversion experiment was performed using multiangle reflectance data from the NASA Multi-angle Imaging Spectro-Radiometer (MISR) on the Earth Observing System Terra satellite, with the goal of obtaining measures of forest fractional crown cover, mean canopy height, and biomass for parts of S.E. Arizona and S. New Mexico (>200,000 km2). MISR red band bidirectional reflectance estimates in nine views mapped to a 250 m grid were used to adjust the Simple Geometric-optical Model (SGM). The soil-understory background signal was decoupled a priori by developing regression relationships with the nadir camera blue, green, and near-infrared reflectance data and the isotropic, geometric, and volume scattering kernel weights of the LiSparse-RossThin kernel-driven bidirectional reflectance distribution function (BRDF) model, adjusted against MISR red band data. The SGM’s mean crown radius and crown shape parameters were adjusted using the Praxis optimization algorithm, allowing retrieval of fractional crown cover, mean canopy height and their dot product, a coarse surrogate for biomass. Retrieved distributions these parameters for forested areas showed good matches with maps from the United States Department of Agriculture (USDA) Forest Service, with R2 values of 0.76, 0.58 and 0.53, post-filtering for high root mean square error (RMSE) and cloud/cloud-shadow contamination. Some areas with important shrub cover are predicted to have low or no woody plant cover, indicating the need to adjust the background calibration and reflecting the difficulty of estimating canopy parameters in low cover environments. This is the first attempt to use data from MISR to produce maps of crown cover, canopy height, and biomass over a large area by seeking to exploit the structural effects of canopies reflected in the observed anisotropy patterns in these explicitly multiangle data.