Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2015
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No abstract has been registered
Abstract
The eddy covariance (EC) method is one key method to quantify fluxes in biogeochemical cycles in general, and carbon and energy transport across the vegetation-atmosphere boundary layer in particular. EC data from the worldwide net of flux towers (Fluxnet) have also been used to validate biogeochemical models. The high resolution data are usually obtained at 20 Hz sampling rate but are affected by missing values and other restrictions. In this contribution, we investigate the nonlinear dynamics of EC fluxes using Recurrence Analysis (RA). High resolution data from the site DE-Bay (Waldstein-Weidenbrunnen) and fluxes calculated at half-hourly resolution from eight locations (part of the La Thuile dataset) provide a set of very long time series to analyze. After careful quality assessment and Fluxnet standard gapfilling pretreatment, we calculate properties and indicators of the recurrent structure based both on Recurrence Plots as well as Recurrence Networks. Time series of RA measures obtained from windows moving along the time axis are presented. Their interpretation is guided by three different questions: (1) Is RA able to discern periods where the (atmospheric) conditions are particularly suitable to obtain reliable EC fluxes? (2) Is RA capable to detect dynamical transitions (different behavior) beyond those obvious from visual inspection? (3) Does RA contribute to an understanding of the nonlinear synchronization between EC fluxes and atmospheric parameters, which is crucial for both improving carbon flux models as well for reliable interpolation of gaps? (4) Is RA able to recommend an optimal time resolution for measuring EC data and for analyzing EC fluxes? (5) Is it possible to detect non-trivial periodicities with a global RA? We will demonstrate that the answers to all five questions is affirmative, and that RA provides insights into EC dynamics not easily obtained otherwise.
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No abstract has been registered
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No abstract has been registered
– Norway Brings the Chinese to Develop the Algae Industry. www.indbiotech.no
Margarita Novoa-Garrido
Authors
Margarita Novoa-GarridoEditors
Anette Tjomsdal susanne wernerAbstract
No abstract has been registered
Authors
Ragnar Våga PedersenAbstract
No abstract has been registered
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High northern latitudes are increasingly exposed to the combination of extreme winter climate and deposition of long-distance dispersed nitrogen pollution. These combined pressures may over time drive changes in plant composition and carbon uptake.
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High northern latitudes are increasingly exposed to the combination of extreme winter climate and deposition of long-distance dispersed nitrogen pollution. The nature in the north is vulnerable, and these combined stresses may over time affect the composition of plant species and carbon uptake. How will North-Norwegian ecosystems tolerate unstable winters and nitrogen pollution?
Editors
Jon SchärerAbstract
High northern latitudes are increasingly exposed to the combination of extreme winter climate and deposition of long-distance dispersed nitrogen pollution. The nature in the north is vulnerable, and these combined pressures may over time drive changes in plant composition and carbon uptake.
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Video: How should India and other countries adapt their agricultural practices to a changing climate? In a new film, researchers explain how they go about in the ClimaAdapt project when developing new rice growing technologies and undertaking capacity building of farmers.