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| Titel |
Development of a portable instrument to measure ozone production rates in the troposphere |
| VerfasserIn |
Sofia Sklaveniti, Nadine Locoge, Philip Stevens, Vinod Kumar, Vinayak Sinha, Sébastien Dusanter |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250106232
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| Publikation (Nr.) |
 EGU/EGU2015-5892.pdf |
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| Zusammenfassung |
| Ground-level ozone is a key species related to air pollution, causing respiratory problems,
damaging crops and forests, and affecting the climate. Our current understanding of the
tropospheric ozone–forming chemistry indicates that net ozone production occurs via
reactions of peroxy radicals (HO2 + RO2) with NO producing NO2, whose photolysis
leads to O3 formation. Production rates of tropospheric ozone, P(O3), depend on
concentrations of oxides of nitrogen (NOx = NO + NO2) and Volatile Organic Compounds
(V OCs), but also on production rates of ROx radicals (OH + HO2 + RO2). The formation
of ozone follows a complex nonlinear chemistry that makes strategies for reducing ozone
difficult to implement. In this context, atmospheric chemistry models are used to develop
emission regulations, but there are still uncertainties associated with the chemical
mechanisms used in these models. Testing the ozone formation chemistry in atmospheric
models is needed, in order to ensure the development of effective strategies for ozone
reduction.
We will present the development of an instrument for direct measurements
of ozone production rates (OPR) in ambient air. The OPR instrument is made of
three components: (i) two quartz flow tubes to sample ambient air, one exposed to
solar radiation and one covered by a UV filter, (ii) a NO2-to-O3 conversion unit,
and (iii) an ozone analyzer. The total amount of ozone exiting each flow tube is
conserved in the form of Ox = NO2 + O3. Ozone production rates P(O3) are derived
from the difference in Ox concentration between the two flow tubes, divided by
the exposure time of air inside the flow tubes. We will present studies that were
carried out in the laboratory to characterize each part of the instrument and we will
discuss the performances of the OPR instrument based on experiments carried out
using synthetic air mixtures of known composition (NOx and V OCs). Chemical
modeling will also be presented to assess the reliability of ozone production rate
measurements. |
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