Retrieval of Ground Surface Reflectance from MODIS Satellite Data with Allowance for Reflectance Heterogeneity and Rugged Topography

An algorithm for retrieving ground surface reflectance from satellite data taking into account the influence of surface reflectance heterogeneity and rugged topography on formation of the adjacency effect and ground surface irradiance is considered. MODIS satellite images of a site with coordinates (50.1°–50.4° N, 90.1°–90.7° E) are used as an example to assess the difference in the results obtained with the suggested algorithm with accounting the ground surface reflectance heterogeneity and rugged topography and neglecting the rugged topography, with the MOD09 algorithm, and with the algorithm without atmospheric correction. The results provided by the suggested algorithm and the MOD09 algorithm well agree. It is shown that the neglect of the rugged topography in the suggested algorithm for the images under study slightly underestimates the reflectance by Δr_surf ≤ 3.46 × 10⁻³ for MODIS band 1, 2.39 × 10⁻³ for MODIS band 2, 7.12 × 10⁻³ for MODIS band 3, and 5.23 × 10⁻³ for MODIS band 4. The algorithm enables increasing the error in retrieving the reflectance from satellite images of strongly rugged heterogeneous surface.