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Title: Investigating the mechanisms responsible for the lack of surface energy balance closure in a central Amazonian tropical rainforest

Abstract

This work investigates the diurnal and seasonal behavior of the energy balance residual (E) that results from the observed difference between available energy and the turbulent fluxes of sensible heat (H) and latent heat (LE) at the FLUXNET BR-Ma2 site located in the Brazilian central Amazon rainforest. The behavior of E is analyzed by extending the eddy covariance averaging length from 30 min to 4 h and by applying an Information Flow Dynamical Process Network to diagnose processes and conditions affecting E across different seasons. Results show that the seasonal turbulent flux dynamics and the Bowen ratio are primarily driven by net radiation (R n), with substantial sub-seasonal variability. The Bowen ratio increased from 0.25 in April to 0.4 at the end of September. Extension of the averaging length from 0.5 (94.6% closure) to 4 h and thus inclusion of longer timescale eddies and mesoscale processes closes the energy balance and lead to an increase in the Bowen ratio, thus highlighting the importance of additional H to E. Information flow analysis reveals that the components of the energy balance explain between 25 and 40% of the total Shannon entropy with higher values during the wet season than the dry season.more » Dry season information flow from the buoyancy flux to E are 30–50% larger than that from H, indicating the potential importance of buoyancy fluxes to closing E. While the low closure highlights additional sources not captured in the flux data and random measurement errors contributing to E, the findings of the information flow and averaging length analysis are consistent with the impact of mesoscale circulations, which tend to transport more H than LE, on the lack of closure.« less

Authors:
 [1];  [2];  [3];  [4];  [5];  [6];  [7];  [8];  [6];  [9];  [8]
  1. Montana State Univ., Bozeman, MT (United States). Dept. of Land Resources and Environmental Sciences; Pennsylvania State Univ., University Park, PA (United States). Dept of Meteorology and Atmospheric Science
  2. Northern Arizona Univ., Flagstaff, AZ (United States). School of Informatics, Computing, and Cyber Systems
  3. Pennsylvania State Univ., University Park, PA (United States). Dept of Meteorology and Atmospheric Science
  4. Embrapa Amazonia Oriental, Belem, PA (Brazil)
  5. Univ. of Kansas, Lawrence, KS (United States). Dept. of Geography and Atmospheric Science
  6. Univ. do Estado do Amazonas (UEA), Manaus, AM (Brazil)
  7. National Inst. of Amazonian Research (INPA), Manaus, AM (Brazil)
  8. Montana State Univ., Bozeman, MT (United States). Dept. of Land Resources and Environmental Science
  9. Brazilian Ministry of Science, Technology and Innovation, Sao Jose dos Campos, Sao Paulo (Brazil). National Inst. for Space Research (INPE)
Publication Date:
Research Org.:
Montana State Univ., Bozeman, MT (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Science Foundation (NSF)
Contributing Org.:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), Fundação de Amparo à Pesquisa do Estado do Amazonas (FAPEAM), Large-scale Biosphere-Atmosphere Experiment in Amazonia (LBA)
OSTI Identifier:
1368353
Grant/Contract Number:
SC0011075; 1552976; 1632810; 1417914
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Agricultural and Forest Meteorology
Additional Journal Information:
Journal Volume: 255; Journal ID: ISSN 0168-1923
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; eddy covariance; energy balance closure; evapotranspiration; information theory sensible heat flux; tropical rainforest

Citation Formats

Gerken, Tobias, Ruddell, Benjamin L., Fuentes, Jose D., Araújo, Alessandro, Brunsell, Nathaniel A., Maia, Jair, Manzi, Antonio, Mercer, Juliane, dos Santos, Rosa Nascimento, von Randow, Celso, and Stoy, Paul C. Investigating the mechanisms responsible for the lack of surface energy balance closure in a central Amazonian tropical rainforest. United States: N. p., 2017. Web. doi:10.1016/j.agrformet.2017.03.023.
Gerken, Tobias, Ruddell, Benjamin L., Fuentes, Jose D., Araújo, Alessandro, Brunsell, Nathaniel A., Maia, Jair, Manzi, Antonio, Mercer, Juliane, dos Santos, Rosa Nascimento, von Randow, Celso, & Stoy, Paul C. Investigating the mechanisms responsible for the lack of surface energy balance closure in a central Amazonian tropical rainforest. United States. doi:10.1016/j.agrformet.2017.03.023.
Gerken, Tobias, Ruddell, Benjamin L., Fuentes, Jose D., Araújo, Alessandro, Brunsell, Nathaniel A., Maia, Jair, Manzi, Antonio, Mercer, Juliane, dos Santos, Rosa Nascimento, von Randow, Celso, and Stoy, Paul C. Sat . "Investigating the mechanisms responsible for the lack of surface energy balance closure in a central Amazonian tropical rainforest". United States. doi:10.1016/j.agrformet.2017.03.023. https://www.osti.gov/servlets/purl/1368353.
@article{osti_1368353,
title = {Investigating the mechanisms responsible for the lack of surface energy balance closure in a central Amazonian tropical rainforest},
author = {Gerken, Tobias and Ruddell, Benjamin L. and Fuentes, Jose D. and Araújo, Alessandro and Brunsell, Nathaniel A. and Maia, Jair and Manzi, Antonio and Mercer, Juliane and dos Santos, Rosa Nascimento and von Randow, Celso and Stoy, Paul C.},
abstractNote = {This work investigates the diurnal and seasonal behavior of the energy balance residual (E) that results from the observed difference between available energy and the turbulent fluxes of sensible heat (H) and latent heat (LE) at the FLUXNET BR-Ma2 site located in the Brazilian central Amazon rainforest. The behavior of E is analyzed by extending the eddy covariance averaging length from 30 min to 4 h and by applying an Information Flow Dynamical Process Network to diagnose processes and conditions affecting E across different seasons. Results show that the seasonal turbulent flux dynamics and the Bowen ratio are primarily driven by net radiation (Rn), with substantial sub-seasonal variability. The Bowen ratio increased from 0.25 in April to 0.4 at the end of September. Extension of the averaging length from 0.5 (94.6% closure) to 4 h and thus inclusion of longer timescale eddies and mesoscale processes closes the energy balance and lead to an increase in the Bowen ratio, thus highlighting the importance of additional H to E. Information flow analysis reveals that the components of the energy balance explain between 25 and 40% of the total Shannon entropy with higher values during the wet season than the dry season. Dry season information flow from the buoyancy flux to E are 30–50% larger than that from H, indicating the potential importance of buoyancy fluxes to closing E. While the low closure highlights additional sources not captured in the flux data and random measurement errors contributing to E, the findings of the information flow and averaging length analysis are consistent with the impact of mesoscale circulations, which tend to transport more H than LE, on the lack of closure.},
doi = {10.1016/j.agrformet.2017.03.023},
journal = {Agricultural and Forest Meteorology},
number = ,
volume = 255,
place = {United States},
year = {Sat Apr 29 00:00:00 EDT 2017},
month = {Sat Apr 29 00:00:00 EDT 2017}
}

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  • This work presents the application of a newly developed method to facilitate the distinction between primary and secondary organic compounds in ambient aerosols based on their chiral analysis. The organic constituents chosen for chiral analysis are the four stereomers of the 2-methyltetrols, (2R,3S)- and (2S,3R)- methylerythritol and (2S,3S)- and (2R,3R)- methylthreitol. Ambient PM10 aerosol samples were collected between June 2008 and June 2009 near Manaus, Brazil, in a remote tropical rainforest environment of central Amazonia. The samples were analyzed for the presence of these four stereomers because qualitatively, in a previous study, they have been demonstrated to have partly primarymore » origins. Thus the origin of these compounds may be primary and secondary from the biosynthesis and oxidation processes of isoprene within plants and also in the atmosphere. Using authentic standards, the quantified concentrations were in average 78.2 and 72.8 ng m-3 for (2R,3S)- and (2S,3R)- methylerythritol and 3.1 and 3.3 ng m-3 for (2S,3S)- and (2R,3R)- methylthreitol during the dry season and 7.1, 6.5, 2.0, and 2.2 ng m-3 during the wet season, respectively. Furthermore, these compounds were found to be outside the confidence interval for racemic mixtures (enantiomeric fraction, Ef = 0.5 -0.01) in nearly all the samples, with deviations of up to 32 % (Ef = 0.61) for (2R,3S)-methylerythritol and 47 % (Ef = 0.65) for (2S,3S)-methylthreitol indicating (99% confidence level) biologically-produced 2-methyltetrols. The minimum primary origin contribution ranged between 0.19 and 29.67 ng m-3 for the 2-methylerythritols and between 0.15 and 1.2 ng m-3 for the 2-methylthreitols. The strong correlation of the diatereomers (racemic 2-methylerythritol and 2-methylthreitol) in the wet season implied a secondary origin. Assuming the maximum secondary contribution in the dry season, the secondary fraction in the wet season was 81-99 % and in the dry season, 10 - 95 %. Nevertheless, from the total 2-methyltetrol mass, the secondary mass represented 31 % whereas the primary 69 %. These results could have been expected for PM10 aerosols and might be different for fine particles at the same site. In addition, correlations with isoprene emission estimates for this site only showed an anti-correlation with 2-methylthreitol suggesting their direct emission from biological activity. The present study reinforces the importance of the analysis of chiral organic compounds to correctly assess the contribution of primary biogenic emissions and isoprene oxidation products to biogenic secondary organic aerosol.« less
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