@Article{PetriGalvLyap:2019:CoAn,
               author = "Petri, Caio Arlanche and Galv{\~a}o, L{\^e}nio Soares and 
                         Lyapustin, Alexei I.",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {NASA Goddard Space 
                         Flight Center}",
                title = "MODIS BRDF effects over Brazilian tropical forests and savannahs: 
                         a comparative analysis",
              journal = "Remote Sensing Letters",
                 year = "2019",
               volume = "10",
               number = "2",
                pages = "95--102",
                month = "Feb.",
             abstract = "Bidirectional reflectance distribution function (BRDF) effects 
                         over Brazilian tropical forests (Amazon) and savannahs (Cerrado) 
                         were inspected for differences in high-quality pixel retrievals, 
                         view direction, view zenith angle (VZA), solar zenith angle (SZA) 
                         and relative azimuth angle (RAA). By comparing Moderate Resolution 
                         Imaging Spectroradiometer (MODIS) data, corrected and 
                         non-corrected for BRDF effects (2000-2014), we evaluated the 
                         magnitude of such effects over reflectance and vegetation indices 
                         (VIs). The VIs were the Enhanced Vegetation Index (EVI) and the 
                         Normalized Difference Vegetation Index (NDVI). From the Amazon to 
                         the Cerrado, we observed a higher frequency of high-quality pixel 
                         retrievals, a decrease in VZA, and an increase in seasonal SZA 
                         amplitude. Brightness increased in the backscattering direction 
                         and with shifts in RAA over tropical forests toward the BRDF 
                         hotspot at the end of dry season (September). Compared to the 
                         savannahs from the Cerrado or those from northern Amazon, stronger 
                         BRDF effects were observed for Amazonian tropical forests and for 
                         the EVI. BRDF changes in the dry season NDVI amplitude (NDVISept 
                         minus NDVIJune) were lower than 5% for both biomes. For the EVI 
                         amplitude, we observed changes up to 20% over the savannahs and 
                         close to 60% for most of the Amazon. However, even after BRDF 
                         correction and in spite of the observed differences close to 0.02, 
                         EVI values from June and September were still statistically 
                         different from each other.",
                  doi = "10.1080/2150704X.2018.1526425",
                  url = "http://dx.doi.org/10.1080/2150704X.2018.1526425",
                 issn = "2150-704X",
             language = "en",
           targetfile = "petri_modis.pdf",
        urlaccessdate = "27 abr. 2024"
}