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Characterizing ecosystem-atmosphere interactions from short to interannual time scales
1Max-Planck-Institute for Biogeochemistry, Jena, Germany
2Norwegian Forest and Landscape Institute, Ås, Norway
3Environmental System Analysis Group, New University of Lisbon, Portugal
4Deptartment of Meteorology, Technical University of Dresden, Germany
5Department of Forest Science and Environment, University of Tuscia, Viterbo, Italy
6Climate Change Unit, European Comission – Joint Research Centre, Ispra, Italy
Abstract. Characterizing ecosystem-atmosphere interactions in terms of carbon and water exchange on different time scales is considered a major challenge in terrestrial biogeochemical cycle research. The respective time series are now partly comprising an observation period of one decade. In this study, we explored whether the observation period is already sufficient to detect cross relationships of the variables beyond the annual cycle as they are expected from comparable studies in climatology.
We explored the potential of Singular System Analysis (SSA) to extract arbitrary kinds of oscillatory patterns. The method is completely data adaptive and performs an effective signal to noise separation.
We found that most observations (NEE, GPP, Reco, VPD, LE, H, u, P) were influenced significantly by low frequency components (interannual variability). Furthermore we extracted a set of nonlinear relationships and found clear annual hysteresis effects except for the NEE-Rg relationship which turned out to be the sole linear relationship in the observation space. SSA provides a new tool to investigate these phenomena explicitly on different time scales. Furthermore, we showed that SSA has great potential for eddy covariance data processing since it can be applied as novel gap filling approach relying on the temporal time series structure only.
Discussion Paper (PDF, 3507 KB) Interactive Discussion (Closed, 5 Comments) Final Revised Paper (BG)
Citation: Mahecha, M. D., Reichstein, M., Lange, H., Carvalhais, N., Bernhofer, C., Grünwald, T., Papale, D., and Seufert, G.: Characterizing ecosystem-atmosphere interactions from short to interannual time scales, Biogeosciences Discuss., 4, 1405-1435, 2007. Bibtex EndNote Reference Manager
