author = "Sousa, Celio Helder Resende de and Hilker, Thomas and Waring, 
                         Richard and Moura, Yhasmin Mendes de and Lyapustin, Alexei",
          affiliation = "{Oregon State University} and {Oregon State University} and 
                         {Oregon State University} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {NASA Goddard Space Flight Center}",
                title = "Progress in remote sensing of photosynthetic activity over the 
                         amazon basin",
              journal = "Remote Sensing",
                 year = "2017",
               volume = "9",
               number = "1",
                pages = "48",
             keywords = "Amazon, Drought, Eddy-flux, GPP, Light use efficiency, MAIAC, 
                         MODIS, Photosynthesis, Sun-induced fluorescence, Tropical 
             abstract = "Although quantifying the massive exchange of carbon that takes 
                         place over the Amazon Basin remains a challenge, progress is being 
                         made as the remote sensing community moves from using traditional, 
                         reflectance-based vegetation indices, such as the Normalized 
                         Difference Vegetation Index (NDVI), to the more functional 
                         Photochemical Reflectance Index (PRI). This new index, together 
                         with satellite-derived estimates of canopy light interception and 
                         Sun-Induced Fluorescence (SIF), provide improved estimates of 
                         Gross Primary Production (GPP). This paper traces the development 
                         of these new approaches, compares the results of their analyses 
                         from multiple years of data acquired across the Amazon Basin and 
                         suggests further improvements in instrument design, data 
                         acquisition and processing. We demonstrated that our estimates of 
                         PRI are in generally good agreement with eddy-flux tower 
                         measurements of photosynthetic light use efficiency (\ε) at 
                         four sites in the Amazon Basin: r2 values ranged from 0.37 to 0.51 
                         for northern flux sites and to 0.78 for southern flux sites. This 
                         is a significant advance over previous approaches seeking to 
                         establish a link between global-scale photosynthetic activity and 
                         remotely-sensed data. When combined with measurements of 
                         Sun-Induced Fluorescence (SIF), PRI provides realistic estimates 
                         of seasonal variation in photosynthesis over the Amazon that 
                         relate well to the wet and dry seasons. We anticipate that our 
                         findings will steer the development of improved approaches to 
                         estimate photosynthetic activity over the tropics.",
                  doi = "10.3390/rs9010048",
                  url = "http://dx.doi.org/10.3390/rs9010048",
                 issn = "2072-4292",
             language = "en",
           targetfile = "sousa_progress.pdf",
        urlaccessdate = "11 abr. 2021"