author = "Breunig, F{\'a}bio Marcelo and Galv{\~a}o, L{\^e}nio Soares and 
                         Santos, Jo{\~a}o Roberto dos and Gitelson, Anatoly A. and Moura, 
                         Yhasmin Mendes de and Teles, Thiago Sousa and Gaida, William",
          affiliation = "{Universidade Federal de Santa Maria (UFSM)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {University of Nebraska} and 
                         {Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)} and {Universidade Federal 
                         de Santa Maria (UFSM)}",
                title = "Spectral anisotropy of subtropical deciduous forest using MISR and 
                         MODIS data acquired under large seasonal variation in solar zenith 
              journal = "International Journal of Applied Earth Observation and 
                 year = "2015",
               volume = "35",
               number = "part B",
                pages = "294--304",
                month = "Mar.",
             keywords = "MISR, MODIS, View-illumination geometry, NDVI, EVI, PROSAIL.",
             abstract = "Recent studies in Amazonian tropical evergreen forests using the 
                         Multi-angle Imaging SpectroRadiometer (MISR) and the Moderate 
                         Resolution Imaging Spectroradiometer (MODIS) have highlighted the 
                         importance of considering the view-illumination geometry in 
                         satellite data analysis. However, contrary to the observed for 
                         evergreen forests, bidirectional effects have not been evaluated 
                         in Brazilian subtropical deciduous forests. In this study, we used 
                         MISR data to characterize the reflectance and vegetation index 
                         anisotropies in subtropical deciduous forest from south Brazil 
                         under large seasonal solar zenith angle (SZA) variation and 
                         decreasing leaf area index (LAI) from the summer to winter. MODIS 
                         data were used to observe seasonal changes in the normalized 
                         difference vegetation index (NDVI) and enhanced vegetation index 
                         (EVI). Topographic effects on their determination were inspected 
                         by dividing data from the summer to winter and projecting results 
                         over a digital elevation model (DEM). By using the PROSAIL, we 
                         investigated the relative contribution of LAI and SZA to 
                         vegetation indices (VI) of deciduous forest. We also simulated and 
                         compared the MISR NDVI and EVI response of subtropical deciduous 
                         and tropical evergreen forests as a function of the large seasonal 
                         SZA amplitude of 33. Results showed that the MODIS-MISR NDVI and 
                         EVI presented higher values in the summer and lower ones in the 
                         winter with decreasing LAI and increasing SZA or greater amounts 
                         of canopy shadows viewed by the sensors. In the winter, NDVI 
                         reduced local topographic effects due to the red-near infrared 
                         (NIR) band normalization. However, the contrary was observed for 
                         the three-band EVI that enhanced local variations in shaded and 
                         sunlit surfaces due to its strong dependence on the NIR band 
                         response. The reflectance anisotropy of the MISR bands increased 
                         from the summer to winter and was stronger in the backscattering 
                         direction at large view zenith angles (VZA). EVI was much more 
                         anisotropic than NDVI and the anisotropy increased from the summer 
                         to winter. It also increased from the forward scatter to the 
                         backscattering direction with the predominance of sunlit canopy 
                         components viewed by MISR, especially at large VZA. Modeling 
                         PROSAIL results confirmed the stronger anisotropy of EVI than NDVI 
                         for the subtropical deciduous and tropical evergreen forests. 
                         PROSAIL showed that LAI and SZA are coupled factors to decrease 
                         seasonally the VIs of deciduous forest with the first one having 
                         greater importance than the latter. However, PROSAIL seasonal 
                         variations in VIs were much smaller than those observed with MODIS 
                         data probably because the effects of shadows in heterogeneous 
                         canopy structures or/and cast by emergent trees and from local 
                         topography were not modeled.",
                  doi = "10.1016/j.jag.2014.09.017",
                  url = "http://dx.doi.org/10.1016/j.jag.2014.09.017",
                 issn = "0303-2434",
             language = "en",
           targetfile = "Breunig_spectral.pdf",
        urlaccessdate = "18 jan. 2021"