@Article{SennaCostShim:2005:CoFiMe,
               author = "Senna, M{\^o}nica C. A. and Costa, Marcos H. and Shimabukuro, 
                         Yosio Edemir",
          affiliation = "Instituto Nacional de Pesquisas Espaciais, Divis{\~a}o de 
                         Sensoriamento Remoto (INPE, DSR), Department of Agricultural and 
                         Environmental Engineering, Federal University of Vi{\c{c}}osa 
                         (UFV), Vi{\c{c}}osa, Minas Gerais, Brazil",
                title = "Fraction of photosynthetically active radiation absorbed by Amazon 
                         tropical forest: A comparison of field measurements, modeling, and 
                         remote sensing",
              journal = "Journal of Geophysical Research",
                 year = "2005",
               volume = "110",
               number = "G01008",
             keywords = "tropical forest, Amazonia, FAPAR, IBIS, MODIS.",
             abstract = "The fraction of absorbed photosynthetically active radiation 
                         (FAPAR) is a vegetation biophysical variable that characterizes 
                         energy, mass, and momentum exchanges and is used extensively in 
                         models that represent the transfer of energy, carbon, water, and 
                         the biogeochemistry of terrestrial ecosystems. This paper compares 
                         three estimates of FAPAR by an Amazonian tropical rain forest. In 
                         the Tapaj{\'o}s National Forest, near Santar{\'e}m, state of 
                         Par{\'a}, Brazil, FAPAR is estimated based on field measurements, 
                         modeling (using IBIS which simulates the fluxes in the 
                         soil-vegetation-atmosphere system considering two vegetation 
                         layers) and remotely sensed Moderate Resolution Imaging 
                         Spectroradiometer (MODIS) monthly FAPAR product, which has not 
                         been validated for a tropical rain forest yet. FAPAR based on 
                         field observations is calculated from incoming and reflected PAR 
                         measurements taken above the canopy, and downward PAR at a 15 m 
                         height, corrected to be representative of the entire canopy, 
                         obtaining an annual mean value of 0.91. FAPAR simulated by the 
                         Integrated Biosphere Simulator (IBIS) is 0.76, while the annual 
                         average FAPAR estimated by MODIS is 0.85. If we consider that 
                         MODIS estimates include only PAR absorbed by leaves, the remote 
                         sensing estimates are very close to field measurements corrected 
                         to include only the absorption by leaves (0.87); hence we conclude 
                         that the MODIS FAPAR product for the tropical rain forest is 
                         reliable to be used in future studies. However, model estimates of 
                         FAPAR for the tropical forest are low, and adjustments on the 
                         algorithm used to calculate the absorbed radiation by the canopy 
                         are necessary.",
                  doi = "10.1029/2004JG000005",
                  url = "http://dx.doi.org/10.1029/2004JG000005",
                 issn = "0148-0227 and 2156-2202",
             language = "en",
           targetfile = "2004JG000005-1.pdf",
        urlaccessdate = "01 maio 2024"
}