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| Titel |
Detection of water vapour absorption around 363nm in measured atmospheric absorption spectra and its effect on DOAS evaluations |
| VerfasserIn |
Johannes Lampel, Oleg L. Polyansky, Alexandra A. Kyuberis, Nikolai F. Zobov, Jonathan Tennyson, Lorenzo Lodi, Denis Pöhler, Udo Frieß, Ulrich Platt, Steffen Beirle, Thomas Wagner |
| 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 |
250127434
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| Publikation (Nr.) |
 EGU/EGU2016-7312.pdf |
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| Zusammenfassung |
| Water vapour is known to absorb light from the microwave region to the blue part of the
visible spectrum at a decreasing magnitude. Ab-initio approaches to model individual
absorption lines of the gaseous water molecule predict absorption lines until its dissociation
limit at 243 nm.
We present first evidence of water vapour absorption at 363 nm from field measurements
based on the POKAZATEL absorption line list by Polyansky et al. (2016) using data from
Multi-Axis differential optical absorption spectroscopy (MAX-DOAS) and Longpath
(LP)-DOAS measurements.
The predicted absorptions contribute significantly to the observed optical depths with up
to 2 × 10−3. Their magnitude correlates well (R2 = 0.89) to simultaneously measured
well-established water vapour absorptions in the blue spectral range from 452-499 nm, but is
underestimated by a factor of 2.6 ± 0.6 in the ab-initio model. At a spectral resolution of
0.5nm this leads to a maximum absorption cross-section value of 5.4 × 10−27 cm2/molec at
362.3nm.
The results are independent of the employed cross-section data to compensate for the
overlayed absorption of the oxygen dimer O4. The newly found absorption can have a
significant impact on the spectral retrieval of absorbing trace-gas species in the spectral range
around 363 nm. Its effect on the spectral analysis of O4, HONO and OClO are
discussed. |
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