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© 2016. This work is published under http://creativecommons.org/licenses/by/3.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.

Abstract

Canopy and aerodynamic conductances (gC and gA) are two of the key land surface biophysical variables that control the land surface response of land surface schemes in climate models. Their representation is crucial for predicting transpiration (ET) and evaporation (λEE) flux components of the terrestrial latent heat flux (λE), which has important implications for global climate change and water resource management. By physical integration of radiometric surface temperature (TR) into an integrated framework of the Penman–Monteith and Shuttleworth–Wallace models, we present a novel approach to directly quantify the canopy-scale biophysical controls onλET and λEE over multiple plant functional types (PFTs) in the Amazon Basin. Combining data from six LBA (Large-scale Biosphere-Atmosphere Experiment in Amazonia) eddy covariance tower sites and a TR-driven physically based modeling approach, we identified the canopy-scale feedback-response mechanism between gC,λET, and atmospheric vapor pressure deficit (DA), without using any leaf-scale empirical parameterizations for the modeling. The TR-based model shows minor biophysical control onλET during the wet (rainy) seasons whereλET becomes predominantly radiation driven and net radiation (RN) determines 75 to 80 % of the variances ofλET. However, biophysical control on λET is dramatically increased during the dry seasons, and particularly the 2005 drought year, explaining 50 to 65 % of the variances ofλET, and indicates λET to be substantially soil moisture driven during the rainfall deficit phase. Despite substantial differences in gA between forests and pastures, very similar canopy–atmosphere “coupling” was found in these two biomes due to soil moisture-induced decrease in gC in the pasture. This revealed the pragmatic aspect of the TR-driven model behavior that exhibits a high sensitivity of gC to per unit change in wetness as opposed to gA that is marginally sensitive to surface wetness variability. Our results reveal the occurrence of a significant hysteresis betweenλET and gC during the dry season for the pasture sites, which is attributed to relatively low soil water availability as compared to the rainforests, likely due to differences in rooting depth between the two systems. Evaporation was significantly influenced bygA for all the PFTs and across all wetness conditions. Our analytical framework logically captures the responses of gC andgA to changes in atmospheric radiation, DA, and surface radiometric temperature, and thus appears to be promising for the improvement of existing land–surface–atmosphere exchange parameterizations across a range of spatial scales.

Details

Title
Canopy-scale biophysical controls of transpiration and evaporation in the Amazon Basin
Author
Mallick, Kaniska 1   VIAFID ORCID Logo  ; Trebs, Ivonne 1 ; Boegh, Eva 2 ; Giustarini, Laura 1 ; Schlerf, Martin 1 ; Drewry, Darren T 3   VIAFID ORCID Logo  ; Hoffmann, Lucien 1 ; Celso von Randow 4   VIAFID ORCID Logo  ; Kruijt, Bart 5 ; Araùjo, Alessandro 6 ; Saleska, Scott 7 ; Ehleringer, James R 8   VIAFID ORCID Logo  ; Domingues, Tomas F 9 ; Jean Pierre H B Ometto 4 ; Nobre, Antonio D 4 ; Osvaldo Luiz Leal de Moraes 10 ; Hayek, Matthew 11   VIAFID ORCID Logo  ; Munger, J William 11   VIAFID ORCID Logo  ; Wofsy, Steven C 11 

 Department of Environmental Research and Innovation, Luxembourg Institute of Science and Technology (LIST), L4422, Belvaux, Luxembourg 
 Department of Science and Environment, Roskilde University, Roskilde, Denmark 
 Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, 91109, USA; Joint Institute for Regional Earth System Science and Engineering, University of California, Los Angeles, California, USA 
 Instituto Nacional de Pesquisas Espaciais (INPE), Centro de Ciência do Sistema Terrestre, São José dos Campos, SP, Brazil 
 Wageningen Environmental Research (ALTERRA), Wageningen, the Netherlands 
 Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA), Belém, PA, Brazil 
 Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, USA 
 Department of Biology, University of Utah, Salt Lake City, UT, USA 
 Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo (USP), São Paulo, SP, Brazil 
10  Centro Nacional de Monitoramento e Alertas de Desastres Naturais, São Paulo, SP, Brazil 
11  Department of Earth and Planetary Science, Harvard University, Cambridge, MA, USA 
Pages
4237-4264
Publication year
2016
Publication date
2016
Publisher
Copernicus GmbH
ISSN
10275606
e-ISSN
16077938
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2414084336
Copyright
© 2016. This work is published under http://creativecommons.org/licenses/by/3.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.