 |
| Titel |
A disjunct eddy accumulation system for the measurement of BVOC fluxes: instrument characterizations and field deployment |
| VerfasserIn |
G. D. Edwards, D. K. Martins, T. Starn, K. Pratt, P. B. Shepson |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1867-1381
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 5, no. 9 ; Nr. 5, no. 9 (2012-09-05), S.2115-2132 |
| Datensatznummer |
250003080
|
| Publikation (Nr.) |
 copernicus.org/amt-5-2115-2012.pdf |
|
|
|
|
|
| Zusammenfassung |
| Biological volatile organic compounds (BVOCs), such as isoprene and
monoterpenes, are emitted in large amounts from forests. Quantification of
the flux of BVOCs is critical in the evaluation of the impact of these
compounds on the concentrations of atmospheric oxidants and on the
production of secondary organic aerosol. A disjunct eddy accumulation (DEA)
sampler system was constructed for the measurement of speciated BVOC fluxes.
Unlike traditional eddy covariance (EC), the relatively new technique of
disjunct sampling differs by taking short, discrete samples that allow for
slower sampling frequencies. Disjunct sample airflow is directed into
cartridges containing sorbent materials at sampling rates proportional to
the magnitude of the vertical wind. Compounds accumulated on the cartridges
are then quantified by thermal desorption and gas chromatography. Herein, we
describe our initial tests to evaluate the disjunct sampler including the
application of vertical wind measurements to create optimized sampling
thresholds. Measurements of BVOC fluxes obtained from DEA during its
deployment above a mixed hardwood forest at the University of Michigan
Biological Station (Pellston, MI) during the 2009 CABINEX field campaign are
reported. Daytime (09:00 a.m. to 05:00 p.m. LT) isoprene fluxes, when averaged over the
footprint of the tower, were 1.31 mg m−2 h−1 which are comparable to
previous flux measurements at this location. Speciated monoterpene fluxes
are some of the first to be reported from this site. Daytime averages were
26.7 μg m−2 h−1 for α-pinene and 10.6 μg m−2 h−1
for β-pinene. These measured concentrations and fluxes were
compared to the output of an atmospheric chemistry model, and were found to
be consistent with our knowledge of the variables that control BVOCs fluxes
at this site. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|