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| Titel |
A new disjunct eddy-covariance system for BVOC flux measurements – validation on CO2 and H2O fluxes |
| VerfasserIn |
R. Baghi, P. Durand, C. Jambert, C. Jarnot, C. Delon, D. Serça, N. Striebig, M. Ferlicoq, P. Keravec |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 5, no. 12 ; Nr. 5, no. 12 (2012-12-21), S.3119-3132 |
| Datensatznummer |
250003216
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| Publikation (Nr.) |
 copernicus.org/amt-5-3119-2012.pdf |
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| Zusammenfassung |
The disjunct eddy covariance (DEC) method is an interesting alternative to
the conventional eddy covariance (EC) method because it allows the
estimation of turbulent fluxes of species for which fast sensors are not
available. We have developed and validated a new disjunct sampling system
(called MEDEE). This system is built with chemically inert materials. Air
samples are taken quickly and alternately in two cylindrical reservoirs,
the internal pressures of which are regulated by a moving piston. The MEDEE system was designed
to be operated either on the ground or aboard an aircraft.
It is also compatible with most analysers since it
transfers the air samples at a regulated pressure. To validate the
system, DEC and EC measurements of CO2 and latent heat fluxes were
performed concurrently during a field campaign. EC fluxes were first
compared to simulated DEC (SDEC) fluxes and then to actual DEC fluxes.
Both the simulated and actual DEC fluxes showed a good agreement with EC
fluxes in terms of correlation. The determination coefficients (R2) were
0.93 and 0.91 for DEC and SDEC latent heat fluxes, respectively. For DEC and
SDEC CO2 fluxes R2 was 0.69 in both cases. The conditions of low
fluxes experienced during the campaign impaired the comparison of the
different techniques especially for CO2 flux measurements. Linear
regression analysis showed an 14% underestimation of DEC fluxes for both
CO2 and latent heat compared to EC fluxes.
A first field campaign, focusing on biogenic volatile organic compound (BVOC)
emissions, was carried out to measure isoprene fluxes above a downy oak
(Quercus Pubescens) forest in the south-east of France. The measured
standard emission rate was in the lower range of reported values in earlier
studies. Further analysis will be conducted through ground-based and airborne
campaigns in the coming years. |
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