BG Biogeosciences BG Biogeosciences 1726-4189 Copernicus Publications Göttingen, Germany 10.5194/bg-11-2661-2014 Evaluating the potential of large-scale simulations to predict carbon fluxes of terrestrial ecosystems over a European Eddy Covariance network Balzarolo M. 2 1 Boussetta S. https://orcid.org/0000-0001-8646-8701 3 Balsamo G. https://orcid.org/0000-0002-1745-3634 3 Beljaars A. 3 Maignan F. 4 Calvet J.-C. https://orcid.org/0000-0001-6425-6492 5 Lafont S. 6 5 Barbu A. 5 Poulter B. https://orcid.org/0000-0002-9493-8600 7 4 Chevallier F. https://orcid.org/0000-0002-4327-3813 4 Szczypta C. 5 8 Papale D. https://orcid.org/0000-0001-5170-8648 1 DIBAF, University of Tuscia, via S. Camillo de Lellis, 01100 Viterbo, Italy PLECO group, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk, Belgium ECMWF, Shinfield Park, Reading, RG2 9AX, England LSCE-IPSL, UMR8212 (CEA/CNRS/UVSQ), Orme des Merisiers, 91191 Gif sur Yvette Cedex, France CNRM-GAME, UMR3589 (Météo-France, CNRS), 42 Avenue Gaspard Coriolis, 31057 Toulouse Cedex 1, France INRA, UMR 1391 ISPA, 33140 Villenave d'Ornon, France Montana State University, Institute on Ecosystems, Department of Ecology, Bozeman, Montana 59717, USA CESBIO, CNES/CNRS/IRD/UPS – UMR5126, 18 avenue. Edouard Belin, bpi 2801, 31401 Toulouse cedex 9, France 20 05 2014 11 10 2661 2678 Copyright: © 2014 M. Balzarolo et al. 2014 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://bg.copernicus.org/articles/11/2661/2014/bg-11-2661-2014.html The full text article is available as a PDF file from https://bg.copernicus.org/articles/11/2661/2014/bg-11-2661-2014.pdf

This paper reports a comparison between large-scale simulations of three different land surface models (LSMs), ORCHIDEE, ISBA-A-gs and CTESSEL, forced with the same meteorological data, and compared with the carbon fluxes measured at 32 eddy covariance (EC) flux tower sites in Europe. The results show that the three simulations have the best performance for forest sites and the poorest performance for cropland and grassland sites. In addition, the three simulations have difficulties capturing the seasonality of Mediterranean and sub-tropical biomes, characterized by dry summers. This reduced simulation performance is also reflected in deficiencies in diagnosed light-use efficiency (LUE) and vapour pressure deficit (VPD) dependencies compared to observations. Shortcomings in the forcing data may also play a role. These results indicate that more research is needed on the LUE and VPD functions for Mediterranean and sub-tropical biomes. Finally, this study highlights the importance of correctly representing phenology (i.e. leaf area evolution) and management (i.e. rotation–irrigation for cropland, and grazing–harvesting for grassland) to simulate the carbon dynamics of European ecosystems and the importance of ecosystem-level observations in model development and validation.

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