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| Titel |
Gap-filling of VOC flux data for deriving annual budgets: Case study at a mountain meadow |
| VerfasserIn |
Ines Bamberger, Lukas Hörtnagl, Armin Hansel, Georg Wohlfahrt |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250080818
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| Zusammenfassung |
| Although the biosphere is currently thought to be the main source for atmospheric volatile
organic compounds (VOCs) longer time series of VOC measurements are barely
available and the accuracy VOC modeling approaches still suffers from a lack of flux
measurement data. However, long-term VOC flux data sets could provide a way to improve
the quality of modeling approaches and make a first step towards a better VOC
quantification.
We used VOC flux data of methanol, acetone, acetaldehyde and the monoterpenes, which
were measured by means of a proton transfer reaction - mass spectrometer PTR-MS utilising
the disjunct eddy covariance method (vDEC) above an intensively managed mountain
grassland in Stubai Valley (Austria), to compare the performance of four different gap filling
approaches and to get complete annual time series of the VOCs for the years 2009 and
2011.
Assuming a zero flux from the grassland during the winter period, when the meadow is
usually covered by snow, the average cumulative VOC fluxes above the grassland show with
103 mg C m-2 in the year 2009 and 464 mg C m-2 in the year 2011 a high
inter-annual variability. The gap filling using the filling method which performs best on the
data introduced mean errors of 20 mg C m-2 in 2009 and 13 mg C m-2 in 2011.
Methanol was with average cumulative emission fluxes of 375 mg C m-2 and
442 mg C m-2 during the year 2009 the main compound contributing to the VOC
balance during both years. The cumulative fluxes of methanol using the four different
gap-filling approaches agreed within a range smaller than 7 percent in 2009 and 2
percent in 2011. During the first year (2009) the cumulative deposition fluxes of
monoterpenes (on average 317 mg C m-2) turned out to have also a big influence
on the overall VOC balance (its cumulative flux variation depending on the used
gap filling method was less than 10 percent). All other compounds showed fluxes
which were below 10 percent of the methanol emission flux in 2009 while flux
contribution of the non-methanol compounds was less than 5 percent of the total budget in
2011. |
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