32 search hits
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Jahresbericht 2010-11 zum Förderprojekt 01879 Untersuchung der Veränderung der Konzentration von Luftbeimengungen und Treibhausgasen im hohen Fichtelgebirge 2007 – 2014
(2012)
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Thomas Foken
Lisa Dirks
- no abstract
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Whole-air relaxed eddy accumulation for the measurement of isotope and trace-gas fluxes
(2012)
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Johannes Ruppert
Michael Riederer
Willi A. Brand
Thomas Foken
- Measuring the isotopic composition of trace gas fluxes can provide additional information on ecosystem gas exchange, when ecosystem processes, like assimilation, discriminate against heavier isotopes. In the case of CO2 exchange, different mass-balances for bulk CO2 and its 13CO2 or CO18O isotopes can be used to separate respiration from photosynthetic assimilation. Up to now, detectors for direct isotope measurements in the field lack the precision needed for fast eddy covariance (EC) flux measurements. The collection of updraft and downdraft whole-air samples using the relaxed eddy accumulation technique (REA) allows simultaneously determining trace gas concentrations and isotope ratios by high precision laboratory analysis. At the same time whole-air REA relaxes several of the technical problems related to REA sampling on traps. In tests using air from a tank the complete whole-air REA sampling system and its foil balloon bag reservoirs showed no signs of contamination after cleaning. The standard deviations of δ13C and δ18O isotope ratios were only slightly higher than the precision specified for the laboratory analysis procedure. First experiment results showed that isotopic differences (up-drafts−downdrafts) were large enough to yield signal to noise ratios greater than five when applying hyperbolic deadbands during REA sampling (HREA). The performance of the instrument and the HREA sampling method are investigated by simulation of the sampling process for bulk CO2, which serves as proxy scalar. Measurements by whole-air HREA in combination with high precision isotope analysis can quantify the isofluxes of 13CO2 and CO18O. Furthermore, additional information is collected on the scalar correlation of bulk CO2 and its stable isotopes, which represents the relatively short timescale of updrafts and downdrafts in the turbulent exchange above an ecosystem. This information is essential to check the scalar similarity assumptions made in the HREA and EC/flask method for the quan-tification of isofluxes.
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Klimawanderweg auf der Landesgartenschau in Bamberg 2012
(2012)
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Thomas Foken
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Documentation and Instruction Manual for the Horizontal Mobile Measuring System (HMMS)
(2011)
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Jörg Hübner
Johannes Olesch
Hubert Falke
Franz X. Meixner
Thomas Foken
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ExchanGE processes in mountainous Regions (EGER)- Documentation of the Intensive Observation Period (IOP3) June, 13th to July, 26th 2011
(2011)
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Andrei Serafimovich
Fabian Eder
Jörg Hübner
Eva Falge
Linda Voß
Matthias Sörgel
Andreas Held
Qianqian Liu
Rafael Eigenmann
Kilian Huber
Henrique F. Duarte
Peter Werle
Eckhard Gast
Stanislaw Cieslik
Liu Heping
Thomas Foken
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Documentation and Instruction Manual of the Eddy-Covariance Software Package TK3
(2011)
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Matthias Mauder
Thomas Foken
- no abstract
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Comparison ot the sonic anemometer Young Model 81000 during VOITEX-99
(1999)
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Thomas Foken
- no abstract
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Proceedings of the International Conference of "Atmospheric Transport and chemistry in Forest Ecosystems" Castle of Thurnau, Germany Oct 5 to Oct 8, 2009
(2009)
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Johannes Lüers
Thomas Foken
- no abstract
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Dokumentation des Experiments STINHO-1 ; 24.09.2001 bis 10.10.2001
(2002)
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Matthias Göckede
Thomas Foken
Jörg Gerchau
Claudia Liebethal
Matthias Mauder
- no abstract
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Klimatologische und mikrometeorologische Forschungen im Rahmen des Bayreuther Institutes für Terrestrische Ökosystemforschung (BITÖK); 1989 - 2004
(2005)
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Thomas Foken
- keine Zusamennfassung
