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@Article{SouzaRRZAGDAM:2019:EvMOAl,
               author = "Souza, Vanessa de Arruda and Roberti, D{\'e}bora Regina and 
                         Ruhoff, Anderson Luis and Zimmer, Tam{\'{\i}}res and Adamatti, 
                         Daniela Santini and Gon{\c{c}}alves, Luis Gustavo 
                         Gon{\c{c}}alves de and Diaz, Marcelo Bortoluzzi and Alves, Rita 
                         de C{\'a}ssia Marques and Moraes, Osvaldo L. L. de",
          affiliation = "{Universidade Federal do Rio Grande do Sul (UFRGS)} and 
                         {Universidade Federal de Santa Maria (UFSM)} and {Universidade 
                         Federal do Rio Grande do Sul (UFRGS)} and {Universidade Federal de 
                         Santa Maria (UFSM)} and {Universidade Federal do Rio Grande do Sul 
                         (UFRGS)} and {Instituto Nacional de Pesquisas Espaciais (INPE)} 
                         and {Universidade Federal de Santa Maria (UFSM)} and {Universidade 
                         Federal do Rio Grande do Sul (UFRGS)} and {Universidade Federal de 
                         Santa Maria (UFSM)}",
                title = "Evaluation of MOD16 algorithm over irrigated rice paddy using flux 
                         tower measurements in southern Brazil",
              journal = "Water",
                 year = "2019",
               volume = "11",
               number = "9",
                pages = "e1911",
                month = "Sept",
             keywords = "evapotranspiration, flooded rice paddy, irrigation, remote 
                         sensing, MODIS, MOD16 algorithm, eddy covariance, meteorological 
                         measurements.",
             abstract = "Evapotranspiration (ET) is an important component of the 
                         hydrological cycle. Understanding the ET process has become of 
                         fundamental importance given the scenario of global change and 
                         increasing water use, especially in the agricultural sector. 
                         Determining ET over large agricultural areas is a limiting factor 
                         due to observational data availability. In this regard, remote 
                         sensing data has been used to estimate ET. In this study, we 
                         evaluated the Moderate-Resolution Imaging Spectroradiometer 
                         (MODIS) land surface ET product estimates (hereafter MOD16 ET - 
                         MODIS Global Terrestrial Evapotranspiration Product) over two rice 
                         paddy areas in Southern Brazil, through the ET measured using the 
                         eddy covariance technique (hereafter EC). The energy balance 
                         components were evaluated during fallow and flooded seasons 
                         showing latent heat flux dominates in both seasons. The results 
                         showed that MOD16 ET underestimated EC measurements. Overall, the 
                         RMSE (root mean square error) ranged between 13.40 and 16.35 mm 
                         8-day(-1) and percent bias (PBIAS) ranged between -33.7% and 
                         -38.7%. We also assessed the ET (measured and estimated) main 
                         drivers, with EC yielding higher correlation against observed net 
                         radiation (R-n) and global radiation (R-g), followed by air 
                         temperature (Temp) and vapor pressure deficit (VPD), whilst MOD16 
                         ET estimates yielded higher correlation against leaf area index 
                         (LAI) and fraction of photosynthetically active radiation (fPAR). 
                         The MOD16 algorithm was forced with meteorological measurements 
                         but the results did not improve as expected, suggesting a low 
                         sensitivity to meteorological inputs. Our results indicated when a 
                         water layer was present over the soil surface without vegetation 
                         (LAI around zero), the largest differences between EC measurements 
                         and MOD16 ET were found. In this period, the expected domain of 
                         soil evaporation was not observed in MOD16 ET physical processes 
                         partition, indicating the algorithm was not able to detect areas 
                         with high soil moisture. In general, the MOD16 ET product 
                         presented low accuracy when compared against experimental 
                         measurements over flooded rice paddy, suggesting more studies are 
                         necessary, in order to reduce uncertainties associated to the land 
                         cover conditions.",
                  doi = "10.3390/w11091911",
                  url = "http://dx.doi.org/10.3390/w11091911",
                 issn = "2073-4441",
             language = "en",
           targetfile = "water-11-01911-v2.pdf",
        urlaccessdate = "12 abr. 2021"
}


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