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Title: The land-atmosphere water flux in the tropics
Authors: Fisher, Joshua B.
Malhi, Yadvinder Singh
Bonal, Damien
Rocha, Humberto Ribeiro da
Araüjo, Alessandro Carioca de
Gamo, Minoru
Goulden, Michael L.
Hirano, Takashi
Huete, Alfredo Ramon
Kondo, Hiroaki
Kumagai, Tomo'omi
Loescher, Henry W.
Miller, Scott Dennis
Nobre, Antônio Donato
Nouvellon, Yann
Oberbauer, Steven F.
Panuthai, Samreong
Roupsard, Olivier
Saleska, Scott Reid
Tanaka, Katsunori
Tanaka, Nobuaki
Tu, Kevin P.
Randow, Celso Von
Keywords: Atmospheric Circulation
Climate Change
Eddy Covariance
Energy Balance
Remote Sensing
Tropical Environment
Vegetation Index
Issue Date: 2009
metadata.dc.publisher.journal: Global Change Biology
metadata.dc.relation.ispartof: Volume 15, Número 11, Pags. 2694-2714
Abstract: Tropical vegetation is a major source of global land surface evapotranspiration, and can thus play a major role in global hydrological cycles and global atmospheric circulation. Accurate prediction of tropical evapotranspiration is critical to our understanding of these processes under changing climate. We examined the controls on evapotranspiration in tropical vegetation at 21 pan-tropical eddy covariance sites, conducted a comprehensive and systematic evaluation of 13 evapotranspiration models at these sites, and assessed the ability to scale up model estimates of evapotranspiration for the test region of Amazonia. Net radiation was the strongest determinant of evapotranspiration (mean evaporative fraction was 0.72) and explained 87% of the variance in monthly evapotranspiration across the sites. Vapor pressure deficit was the strongest residual predictor (14%), followed by normalized difference vegetation index (9%), precipitation (6%) and wind speed (4%). The radiation-based evapotranspiration models performed best overall for three reasons: (1) the vegetation was largely decoupled from atmospheric turbulent transfer (calculated from Ω decoupling factor), especially at the wetter sites; (2) the resistance-based models were hindered by difficulty in consistently characterizing canopy (and stomatal) resistance in the highly diverse vegetation; (3) the temperature-based models inadequately captured the variability in tropical evapotranspiration. We evaluated the potential to predict regional evapotranspiration for one test region: Amazonia. We estimated an Amazonia-wide evapotranspiration of 1370mmyr-1, but this value is dependent on assumptions about energy balance closure for the tropical eddy covariance sites; a lower value (1096mmyr-1) is considered in discussion on the use of flux data to validate and interpolate models. © 2009 The Authors Journal compilation © 2009 Blackwell Publishing Ltd.
metadata.dc.identifier.doi: 10.1111/j.1365-2486.2008.01813.x
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