@Article{AlmeidaDelGalAraRam:2018:ImMOGr,
author = "Almeida, Catherine Torres de and Delgado, Rafael Coll and
Galv{\~a}o, L{\^e}nio Soares and Arag{\~a}o, Luiz Eduardo
Oliveira e Cruz de and Ramos, Mar{\'{\i}}a Concepci{\'o}n",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and
{Universidade Federal Rural do Rio de Janeiro (UFRRJ)} and
{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto
Nacional de Pesquisas Espaciais (INPE)} and {University of
Lleida}",
title = "Improvements of the MODIS Gross Primary Productivity model based
on a comprehensive uncertainty assessment over the Brazilian
Amazonia",
journal = "ISPRS Journal of Photogrammetry and Remote Sensing",
year = "2018",
volume = "145",
pages = "268--283",
keywords = "GPP, MODIS, Amazon.",
abstract = "Tropical forests and savannas are responsible for the largest
proportion of global Gross Primary Productivity (GPP), a major
component of the global carbon cycle. However, there are still
deficiencies in the spatial and temporal information of tropical
photosynthesis and its relations with environmental controls. The
MOD17 product, based on the Light Use Efficiency (LUE) concept,
has been updated to provide GPP estimates around the globe. In
this research, the MOD17 GPP collections 5.0, 5.5 and 6.0 and
their sources of uncertainties were assessed by using measurements
of meteorology and eddy covariance GPP from eight flux towers in
Brazilian tropical ecosystems, from 2000 to 2006. Results showed
that the MOD17 collections tend to overestimate GPP at low
productivity sites (bias between 111% and 584%) and underestimate
it at high productivity sites (bias between \−2% and
\−18%). Overall, the MOD17 product was not able to capture
the GPP seasonality, especially in the equatorial sites.
Recalculations of MOD17 GPP using site-specific meteorological
data, corrected land use/ land cover (LULC) classification, and
tower-based LUE parameter showed improvements for some sites.
However, the improvements were not sufficient to estimate the GPP
seasonality in the equatorial forest sites. The use of a new soil
moisture constraint on the LUE, based on the Evaporative Fraction,
just showed improvements in water-limited sites. Modifications in
the algorithm to account for separate LUE for cloudy and clear sky
days presented noticeably improved GPP estimates in the tropical
ecosystems investigated, both in magnitude and in seasonality. The
results suggest that the high cloudiness makes the diffuse
radiation an important factor to be considered in the LUE control,
especially over dense forests. Thus, the MOD17 GPP algorithm needs
more updates to accurately estimate productivity in tropical
ecosystems.",
doi = "10.1016/j.isprsjprs.2018.07.016",
url = "http://dx.doi.org/10.1016/j.isprsjprs.2018.07.016",
issn = "0924-2716 and 1872-8235",
label = "lattes: 5507769922001047 3 AlmeidaDelGalAraRam:2018:ImMOGr",
language = "en",
targetfile = "almeida_improvements.pdf",
urlaccessdate = "27 abr. 2024"
}