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| Titel |
NO2 seasonal evolution in the north subtropical free troposphere |
| VerfasserIn |
M. Gil-Ojeda, M. Navarro-Comas, L. Gomez-Martin, J. A. Adame, A. Saiz-Lopez, C. A. Cuevas, Y. González, O. Puentedura, E. Cuevas, J.-F. Lamarque, D. Kinninson, S. Tilmes |
| 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 ; 15, no. 18 ; Nr. 15, no. 18 (2015-09-25), S.10567-10579 |
| Datensatznummer |
250120050
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| Publikation (Nr.) |
 copernicus.org/acp-15-10567-2015.pdf |
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| Zusammenfassung |
Three years of multi-axis differential optical absorption spectroscopy
(MAXDOAS) measurements (2011–2013) have been used for estimating the
NO2 mixing ratio along a horizontal line of sight from the high
mountain subtropical observatory of Izaña, at 2370 m a.s.l. (NDACC
station, 28.3° N, 16.5° W). The method is
based on horizontal path calculation from the O2–O2 collisional
complex at the 477 nm absorption band which is measured simultaneously to
the NO2 column density, and is applicable under low aerosol-loading conditions.
The MAXDOAS technique, applied in horizontal mode in the free troposphere,
minimizes the impact of the NO2 contamination resulting from the
arrival of marine boundary layer (MBL) air masses from thermally forced upwelling breeze during
middle hours of the day. Comparisons with in situ observations show that
during most of the measuring period, the MAXDOAS is insensitive or very
slightly sensitive to the upwelling breeze. Exceptions are found for pollution
events during southern wind conditions. On these occasions, evidence of fast,
efficient and irreversible transport from the surface to the free
troposphere is found.
Background NO2 volume mixing ratio (vmr), representative of the remote free troposphere,
is in the range of 20–45 pptv. The observed seasonal evolution shows an annual
wave where the peak is in phase with the solar radiation. Model simulations
with the chemistry–climate CAM-Chem model are in good agreement with the
NO2 measurements, and are used to further investigate the possible
drivers of the NO2 seasonality observed at Izaña. |
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