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| Titel |
Ozone stress as a driving force of sesquiterpene emissions: a suggested parameterisation |
| VerfasserIn |
E. Bourtsoukidis, B. Bonn, A. Dittmann, H. Hakola, H. Hellén, S. Jacobi |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 11 ; Nr. 9, no. 11 (2012-11-07), S.4337-4352 |
| Datensatznummer |
250007379
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| Publikation (Nr.) |
 copernicus.org/bg-9-4337-2012.pdf |
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| Zusammenfassung |
Sesquiterpenes (C15H24) are semi-volatile organic compounds
emitted by vegetation and are of interest in atmospheric research because
they influence the oxidative capacity of the atmosphere and contribute to
the formation of secondary organic aerosols. However, little is known about
their emission pattern and no established parameterisation is available for
global emission models. The aim of this study is to investigate a Central
European spruce forest and its emission response to meteorological and
environmental parameters, looking for a parameterisation that incorporates
heat and oxidative stress as the main driving forces of the induced
emissions. Therefore, a healthy ca. 80 yr old Norway spruce (Picea abies)
tree was selected and a dynamical vegetation enclosure technique was applied
from April to November 2011. The emissions clearly responded to temperature
changes with small variations in the β-factor along the year (βspring = 0.09 ± 0.01, βsummer = 0.12 ± 0.02,
βautumn = 0.11 ± 0.02). However, daily calculated values
revealed a vast amount of variability in temperature dependencies
((0.02 ± 0.002) < β < (0.27 ± 0.04)) with no
distinct seasonality.
By separating the complete dataset in 10 different ozone regimes, we found
that in moderately or less polluted atmospheric conditions the main driving
force of sesquiterpene emissions is the temperature, but when ambient ozone
mixing ratios exceed a critical threshold of (36.6 ± 3.9) ppbv,
the emissions become primarily correlated with ozone. Considering the
complete dataset, cross correlation analysis resulted in highest correlation
with ambient ozone mixing ratios (CCO3 = 0.63 ± 0.01;
CCT = 0.47 ± 0.02 at t = 0 h for temperature) with a time shift
2–4 h prior to the emissions. An only temperature dependent algorithm was
found to substantially underestimate the induced emissions (20% of the
measured; R2 = 0.31). However, the addition of an ozone dependent term
improved substantially the fitting between measured and modelled emissions
(81% of the modelled emissions could be explained by the measurements;
R2 = 0.63), providing confidence about the reliability of the suggested
parameterisation for the spruce forest site investigated. |
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