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| Titel |
Investigating the long-term evolution of subtropical ozone profiles applying ground-based FTIR spectrometry |
| VerfasserIn |
O. E. García, M. Schneider, A. Redondas, Y. González, F. Hase, T. Blumenstock, E. Sepúlveda |
| 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 ; 5, no. 11 ; Nr. 5, no. 11 (2012-11-28), S.2917-2931 |
| Datensatznummer |
250003183
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| Publikation (Nr.) |
 copernicus.org/amt-5-2917-2012.pdf |
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| Zusammenfassung |
| This study investigates the long-term evolution of subtropical ozone profile
time series (1999–2010) obtained from ground-based FTIR (Fourier Transform
InfraRed) spectrometry at the Izaña Observatory ozone super-site.
Different ozone retrieval strategies are examined, analysing the influence of
an additional temperature retrieval and different constraints. The
theoretical assessment reveals that the FTIR system is able to resolve four
independent ozone layers with a precision of better than 6% in the
troposphere and of better than 3% in the lower, middle and upper
stratosphere. This total error includes the smoothing error, which dominates
the random error budget. Furthermore, we estimate that the measurement noise
as well as uncertainties in the applied atmospheric temperature profiles and
instrumental line shape are leading error sources. We show that a
simultaneous temperature retrieval can significantly reduce the total random
errors and that a regular determination of the instrumental line shape is
important for producing a consistent long-term dataset. These theoretical
precision estimates are empirically confirmed by daily intercomparisons with
Electro Chemical Cell (ECC) sonde profiles. In order to empirically document
the long-term stability of the FTIR ozone profile data we compare the linear
trends and seasonal cycles as obtained from the FTIR and ECC time series.
Concerning seasonality, in winter both techniques observe stratospheric ozone
profiles that are typical middle latitude profiles (low tropopause, low ozone
maximum concentrations) and in summer/autumn profiles that are typical
tropical profiles (high tropopause, high maximum concentrations). The linear
trends estimated from the FTIR and the ECC datasets agree within their error
bars. For the FTIR time series, we observe a significant negative
trend in the upper troposphere/lower stratosphere of about
−0.2% yr−1 and a significant positive trend in the middle and
upper stratosphere of about +0.3% yr−1 and +0.4% yr−1,
respectively. Identifying such small trends is a difficult task for any
measurement technique. In this context, super-sites applying different
techniques are very important for the detection of reliable ozone trends. |
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