Monitoring MODIS calibration stability of visible and near-IR bands from observed top-of-atmosphere BRDF-normalized reflectances over Libyan Desert and Antarctic surfaces

摘要: MODIS is one of the major instruments for National Aeronautics and Space Administration (NASA) Earth Observing System (EOS) missions. It on-board both EOS Terra Aqua spacecrafts, launched in December 1999 and May 2002, respectively. Each provides spectral observations multiple angular views reflectance at the top atmosphere (TOA) around globe. This study focuses on visible (0.65μm) band near-IR (0.84μm) band to examine variations observed TOA reflectances due impact bi-directional reflectance distribution function (BRDF). Two highly uniform ground sites Libyan Desert Antarctica are selected. The variation as a view zenith angle fixed solar studied based reflectances obtained from granules over passing each site. The variation at a collected 16-day repeatable orbits, which have same view geometry relative Results show that near nadir desert site close to Lambertian pattern while those Dome C. strongly anisotropic. Comparison simple Lambertian and BRDF correction made terms their effectiveness removing trending variations. BRDF correction semi-empirical model consisting two kernel-driven components. both corrections able significantly remove site, produce remarkably low variability less than 2% linear fit. normalized trends year 2000 2007, the bands dropped only 1.7 1.2% total,