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| Titel |
Flux measurements of volatile organic compounds at SMEAR II using surface layer gradient method |
| VerfasserIn |
P. Rantala, R. Taipale, T. M. Ruuskanen, J. Aalto, M. K. Kajos, J. Patokoski, S. Schallhart, J. Rinne |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250067214
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| Zusammenfassung |
| Volatile organic compounds (VOCs) are mostly emitted into atmosphere from natural
sources. Some of the compounds, such as monoterpenes, are highly reactive and seem to have
major contributions to aerosol particle formation and growth, thus these compounds are also
connected to the global climate change. Approximately 50 % of the biogenic emissions is
coming from the tropical rain forests, 15-20 % from the boreal forests and the rest from the
other sources like fields and oceans.
In order to understand seasonal and interannual changes in VOC emissions long term
emission measurements would be of great importance. However, long-term VOC
emission measurements are extremely sparse. Our aim is to develop reliable and
feasible method to measure ecosystem scale VOC emissions by micrometeorological
methods. In the past decade the disjunct eddy covariance method with proton transfer
reaction quadrupole mass spectrometry (DEC/PTR-QMS) has been the method of
choise for VOC flux measurements. However, automatically data post-processing,
crucial for long term measurement, remains a challenge, especially in low flux
conditions.
To by-pass these problems we can apply a surface layer gradient technique with
PTR-QMS (SLG/PTR-QMS) for long term VOC flux measurements. In this technique fluxes
are obtained using measured vertical profiles on VOC concentrations with Monin-Obukhov
similarity theory. Albeit more indirect method than DEC, this classical method holds promise
for long term measurement.
The measurements wer conducted in Hyytiälä at SMEAR II station (61° 51’ N, 24°
17’ E, 180 m a.m.s.l.) since summer 2010. Hyytiälä represents a typical boreal
region with clear snow covered winters and annual average temperature has been
approximately 3.3°C. Clear cumulative positive flux of methanol, acetaldehyde,
ethanol/formic acid, acetone, MBO-fragment/isoprene, and monoterpenes were observed. |
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