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| Titel |
Autonomous Long-Path DOAS Measurements of Tropospheric Trace Gases at Neumayer Station III, Antarctica: First Results |
| VerfasserIn |
Jan-Marcus Nasse, Udo Frieß, Denis Pöhler, Rolf Weller, Ulrich Platt |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250129531
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| Publikation (Nr.) |
 EGU/EGU2016-9658.pdf |
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| Zusammenfassung |
| Reactive Halogen Species (RHS, like IO, BrO, ClO, etc.) have an important impact on
atmospheric chemistry. In Polar Regions, the role of halogen radical chemistry has been
subject of intensive research for more than two decades. Among the most prominent effects
of RHS on the Polar atmosphere are the change of the oxidative capacity of the troposphere
including wide-spread and frequently virtually complete destruction of tropospheric ozone, in
particular during springtime, as well as the oxidation and subsequent deposition of gaseous
elemental mercury.
The number of field observations and the understanding of the underlying processes
varies greatly between bromine, iodine and chlorine compounds. While elevated BrO
concentrations resulting from autocatalytic processes (the so-called bromine explosion
mechanism) are frequently observed, the abundance and influence of iodine is still subject to
discussions and available observations give no consistent picture. With only a few direct
observations of chlorine compounds, such as ClO and OClO, the role of tropospheric chlorine
chemistry remains poorly understood to date, despite strong evidence for its relevance. The
lack of observations of chlorine radicals is mainly due to the challenging detection,
particularly in the case of ClO. Scattered sunlight DOAS measurements, which
are available from a number of Polar locations, are not sensitive for ClO, due to
insufficient radiation intensity in the UV spectral region (<308nm) where this molecule is
absorbing.
Here we present the overall design and first results of a novel Long Path DOAS
(Differential Optical Absorption Spectroscopy) instrument with an active light source suitable
for the detection of ClO. It has been set up at the German Research Station Neumayer III in
coastal Antarctica during the summer season 2015/16 and is planned to operate
autonomously for at least one year. The instrument is able to detect - in addition to ClO -
many trace gases absorbing in the UV/Vis including BrO, OClO, IO, I2, OIO, ozone, NO2,
H2O, O4, and SO2 simultaneously at a temporal resolution of 1-3 minutes. Due to its active
light source, it can continue measurements during the (Polar) night and hence complements
the time series of a scattered light (MAX-DOAS) instrument we have been operating at
Neumayer since 1999. |
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