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| Titel |
An aircraft based three channel broadband cavity enhanced absorption spectrometer for simultaneous measurements of NO3, N2O5 and NO2 |
| VerfasserIn |
O. J. Kennedy, B. Ouyang, J. M. Langridge, M. J. S. Daniels, S. Bauguitte, R. Freshwater, M. W. McLeod, C. Ironmonger, J. Sendall, O. Norris, R. Nightingale, S. M. Ball, R. L. Jones |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 4, no. 9 ; Nr. 4, no. 9 (2011-09-07), S.1759-1776 |
| Datensatznummer |
250002088
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| Publikation (Nr.) |
 copernicus.org/amt-4-1759-2011.pdf |
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| Zusammenfassung |
| A three channel broadband cavity enhanced absorption spectroscopy (BBCEAS)
instrument has been developed for airborne measurements of atmospheric trace
gases involved in night-time oxidation chemistry and air quality. The
instrument was deployed on board the Facility for Airborne Atmospheric
Measurements BAe 146-301 atmospheric research aircraft during the Role of
Nighttime Chemistry in Controlling the Oxidising Capacity of the Atmosphere
(RONOCO) measurement campaigns between December 2009 and January 2011. In
its present configuration (i.e. specifications of the cavity optics and
spectrometers) the instrument is designed to measure NO3,
N2O5 (by detection of NO3 after thermal dissociation of
N2O5), H2O and NO2 by characterising the wavelength
dependent optical attenuation within ambient samples by molecular absorption
around 662 nm (NO3 and H2O) and 445 nm (NO2). This paper
reports novel advancements in BBCEAS instrumentation including a refined
method for performing BBCEAS mirror reflectivity calibrations using
measurements of the phase delay introduced by the optical cavities to
amplitude modulated radiation. Furthermore, a new methodology is introduced
for fitting the strong but unresolved transitions of water vapour, which is
required for accurate retrieval of water absorption features from the 662 nm
absorption band used to measure NO3 concentrations. The paper also
details the first example of airborne measurements of NO3,
N2O5 and NO2 over Europe from a flight over the North Sea and
Thames Estuary on the night of the 20 July 2010, one of the most polluted
days of the RONOCO summertime flying period. As part of this analysis, the
performance of the BBCEAS instrument is assessed by comparing airborne
NO2 measurements to those reported concurrently by a photolytic
chemiluminescence based detector. |
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