Preliminary validation and application of the angle products of MODIS AFX based on kernel-driven model

The semi-empirical kernel-driven Bidirectional Reflectance Distribution Function (BRDF) models have been widely used in many remotely sensed BRDF/albedo products such as MODIS products for their simplicity and physical interpretation[1]. Based on anisotropic flat index (AFX) derived from the model^[2], magnitude inversion algorithm which takes BRDF archetypes as prior knowledge have been proposed^[3]. In order to validate the ability of AFX to indicate land surface anisotropy, the relations between AFX and BRDF shapes of several typical land cover types are described in this paper. Besides, we compare the values of prototype inversion algorithm based on AFX with the original full inversion algorithm. Finally, we study relations between AFX and LAI with the simulation data of the two-layer canopy reflectance model of KUUSK to apply AFX, which may guide future research of retrieving the vegetation parameters.