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Analyzing the causes and spatial pattern of the European 2003 carbon flux anomaly in Europe using seven models
1Max-Planck Institute for Biogeochemistry, Hans-Knöll Strasse 10, 07745 Jena, Germany
2Potsdam Inst. for Climate Impact Res. (PIK), Telegrafenberg A 31, 14473 Potsdam, Germany
3LSCE, Orme point courrier 129, CEA-Orme des Merisiers, 91191 Gif-Sur-Yvette, CEDEX, France
4DISAFRI, University of Tuscia, 01100 Viterbo, Italy
5Department of Plant Ecology, University of Bayreuth, 95440 Bayreuth, Germany
6Hadley Centre, Met Office, Exeter, UK
7Centro di Ecologia Alpina (CEALP), Trento, Italy
8GKSS-Research Centre, Institute for Coastal Research, Development of operational systems, Max-Planck-Straße 1, 21502 Geesthacht, Germany
Abstract. Globally, the year 2003 is associated with one of the largest atmospheric CO2 rises on record. In the same year, Europe experienced an anomalously strong flux of CO2 from the land to the atmosphere associated with an exceptionally dry and hot summer in Western and Central Europe. In this study we analyze the magnitude of this carbon flux anomaly and key driving ecosystem processes using simulations of seven terrestrial ecosystem models of different complexity and types (process-oriented and diagnostic). We address the following questions: (1) how large were deviations in the net European carbon flux in 2003 relative to a short-term baseline (1998–2002) and to longer-term variations in annual fluxes (1980 to 2005), (2) which regions exhibited the largest shift in carbon fluxes during the growing season 2003, and (3) which processes controlled the carbon balance anomaly .
In Western and Central Europe, the anomaly in net ecosystem productivity (NEP) over growing season 2003 was outside the 1σ bound of the carbon flux anomalies for 1980–2005. The estimated growing season anomaly ranged between –29 and –196 Tg C for Western Europe and between 13 and –94 Tg C for Central Europe depending on the model used. All models responded to a dipole pattern of the climate anomaly in 2003. In Western and Central Europe NEP was reduced due to heat and drought. Over Western Russia NEP was decreased in response to lower than normal temperatures and high precipitation. While models agree on changes in simulated NEP and gross primary productivity anomalies in 2003 over Western and Central Europe, models diverge in the estimates of anomalies in ecosystem respiration. Except for two process models which simulate respiration increase, most models simulated a decrease in ecosystem respiration in 2003. The diagnostic models showed a weaker decrease in ecosystem respiration than the process-oriented models.
Based on the multi-model simulations we estimated the total carbon flux anomaly over the 2003 growing season in Europe to range between –0.02 and –0.27 Pg C relative to the net flux in 1998–2002.
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Citation: Vetter, M., Churkina, G., Jung, M., Reichstein, M., Zaehle, S., Bondeau, A., Chen, Y., Ciais, P., Feser, F., Freibauer, A., Geyer, R., Jones, C., Papale, D., Tenhunen, J., Tomelleri, E., Trusilova, K., Viovy, N., and Heimann, M.: Analyzing the causes and spatial pattern of the European 2003 carbon flux anomaly in Europe using seven models, Biogeosciences Discuss., 4, 1201-1240, 2007. Bibtex EndNote Reference Manager
