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| Titel |
Airborne DOAS measurements in Arctic: vertical distributions of aerosol extinction coefficient and NO2 concentration |
| VerfasserIn |
A. Merlaud, M. Roozendael, N. Theys, C. Fayt, C. Hermans, B. Quennehen, A. Schwarzenboeck, G. Ancellet, M. Pommier, J. Pelon, J. Burkhart, A. Stohl, M. Mazière |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 17 ; Nr. 11, no. 17 (2011-09-07), S.9219-9236 |
| Datensatznummer |
250010059
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| Publikation (Nr.) |
 copernicus.org/acp-11-9219-2011.pdf |
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| Zusammenfassung |
We report on airborne Differential Optical Absorption Spectroscopy (DOAS)
measurements of aerosol extinction and NO2 tropospheric profiles performed
off the North coast of Norway in April 2008. The DOAS instrument was
installed on the Safire ATR-42 aircraft during the POLARCAT-France spring
campaign and recorded scattered light spectra in near-limb geometry using a
scanning telescope. We use O4 slant column measurements to derive the
aerosol extinction at 360 nm. Regularization is based on the maximum a
posteriori solution, for which we compare a linear and a logarithmic
approach. The latter inherently constrains the solution to positive values
and yields aerosol extinction profiles more consistent with independently
measured size distributions. We present results from two soundings performed
on 8 April 2008 above 71° N, 22° E and on 9 April 2008 above
70° N, 17.8° E. The first profile shows aerosol extinction and
NO2 in the marine boundary layer with respective values of
0.04 ± 0.005 km−1 and 1.9 ± 0.3 × 109 molec cm−3. A second extinction
layer of 0.01 ± 0.003 km−1 is found at 4 km altitude where the NO2 concentration is 0.32 ± 0.2 × 109 molec cm−3. During the second
sounding, clouds prevent retrieval of profile parts under 3 km altitude but a
layer with enhanced extinction (0.025 ± 0.005 km−1) and NO2
(1.95 ± 0.2 × 109 molec cm−3) is clearly detected at 4 km
altitude.
From CO and ozone in-situ measurements complemented by back-trajectories, we
interpret the measurements in the free troposphere as, for the first
sounding, a mix between stratospheric and polluted air from Northern Europe
and for the second sounding, polluted air from Central Europe containing
NO2. Considering the boundary layer measurements of the first flight,
modeled source regions indicate closer sources, especially the Kola Peninsula
smelters, which can explain the NO2 enhancement not correlated with a CO
increase at the same altitude. |
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