Title: Effect of spatial sampling from European flux towers for estimating carbon and water fluxes with artificial neural networks

Abstract

Abstract Empirical modeling approaches are frequently used to upscale local eddy covariance observations of carbon, water, and energy fluxes to regional and global scales. The predictive capacity of such models largely depends on the data used for parameterization and identification of input‐output relationships, while prediction for conditions outside the training domain is generally uncertain. In this work, artificial neural networks (ANNs) were used for the prediction of gross primary production (GPP) and latent heat flux (LE) on local and European scales with the aim to assess the portion of uncertainties in extrapolation due to sample selection. ANNs were found to be a useful tool for GPP and LE prediction, in particular for extrapolation in time (mean absolute error MAE for GPP between 0.53 and 1.56 gC m ⁻²  d ⁻¹ ). Extrapolation in space in similar climatic and vegetation conditions also gave good results (GPP MAE 0.7–1.41 gC m ⁻²  d ⁻¹ ), while extrapolation in areas with different seasonal cycles and controlling factors (e.g., the tropical regions) showed noticeably higher errors (GPP MAE 0.8–2.09 gC m ⁻²  d ⁻¹ ). The distribution and the number of sites used for ANN training had a remarkable effect on prediction uncertainty in both, regional GPP and LE budgetsmore » and their interannual variability. Results obtained show that for ANN upscaling for continents with relatively small networks of sites, the error due to the sampling can be large and needs to be considered and quantified. The analysis of the spatial variability of the uncertainty helped to identify the meteorological drivers driving the uncertainty.« less

Authors:

Papale, Dario ^[1]; Black, T. Andrew ^[2]; Carvalhais, Nuno ^[3]; Cescatti, Alessandro ^[4]; Chen, Jiquan ^[5]; Jung, Martin ^[6]; Kiely, Gerard ^[7]; Lasslop, Gitta ^[8]; Mahecha, Miguel D. ^[6]; Margolis, Hank ^[9]; Merbold, Lutz ^[10]; Montagnani, Leonardo ^[11]; Moors, Eddy ^[12]; Olesen, Jørgen E.  ^[13];

• Search DOE PAGES for author "Olesen, Jørgen E."
• Search DOE PAGES for ORCID "0000-0002-6639-1273"

Reichstein, Markus ^[6]; Tramontana, Gianluca ^[14]; van Gorsel, Eva ^[15]; Wohlfahrt, Georg  ^[16];

• Search DOE PAGES for author "Wohlfahrt, Georg"
• Search DOE PAGES for ORCID "0000-0003-3080-6702"

Ráduly, Botond ^[17]

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+ Show Author Affiliations

1. Department for Innovation in Biological, Agro‐Food and Forest Systems University of Tuscia Viterbo Italy, CzechGlobe, Global Change Research Centre AS CR Brno Czech Republic
2. Faculty of Land and Food Systems University of British Columbia Vancouver British Columbia Canada
3. Department Biogeochemical Integration Max Planck Institute for Biogeochemistry Jena Germany, Departamento de Ciências e Engenharia do Ambiente, Faculdade de Ciências e Tecnologia Universidade Nova de Lisboa Lisbon Portugal
4. Institute for Environment and Sustainability, Joint Research Centre European Commission Ispra Italy
5. CGCEO/Department of Geography Michigan State University East Lansing Michigan USA
6. Department Biogeochemical Integration Max Planck Institute for Biogeochemistry Jena Germany
7. Civil and Environmental Engineering Department, and Environmental Research Institute University College Cork Cork Ireland
8. Fire in the Earth System, Land in the Earth System Max Planck Institute for Meteorology Hamburg Germany
9. Centre d'étude de la forêt Université Laval Quebec Quebec Canada
10. Department of Environmental Systems Science, Institute of Agricultural Sciences ETH Zurich Zurich Switzerland
11. Forest Services, Autonomous Province of Bolzano Bolzano Italy, Faculty of Sciences and Technology Free University of Bolzano Bolzano Italy
12. Alterra Wageningen UR Wageningen Netherlands, VU University Amsterdam Amsterdam Netherlands
13. Department of Agroecology Aarhus University Tjele Denmark
14. Department for Innovation in Biological, Agro‐Food and Forest Systems University of Tuscia Viterbo Italy
15. CSIRO Oceans and Atmosphere Flagship Yarralumla Australia
16. Institute for Ecology University of Innsbruck Innsbruck Austria, European Academy Bolzano Bolzano Italy
17. Department of Bioengineering Sapientia Hungarian University of Transylvania Miercurea Ciuc Romania

Publication Date:

Fri Oct 09 00:00:00 EDT 2015

Sponsoring Org.:

USDOE

OSTI Identifier:

1402304

Resource Type:

Publisher's Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Biogeosciences

Additional Journal Information:

Journal Name: Journal of Geophysical Research. Biogeosciences Journal Volume: 120 Journal Issue: 10; Journal ID: ISSN 2169-8953

Publisher:

American Geophysical Union (AGU)

Country of Publication:

United States

Language:

English