Title: Characterizing Ecosystem-Atmosphere Interactions from Short to Interannual Time Scales
Citation: Biogeosciences vol. 4 no. 5 p. 743-758
Publication Year: 2007
JRC N°: JRC40117
ISSN: 1726-4170
URI: http://www.biogeosciences.net/4/743/2007/bg-4-743-2007.html
Type: Articles in Journals
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 5 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 10 effective signal to noise separation. We found that most observations (NEE, GP P , Reco, V P D, 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 15 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 fillingapproach relying on the temporal time series structure only.
JRC Institute:Institute for Environment and Sustainability

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