@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 = "19 abr. 2024"
}