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| Titel |
Tropospheric ozone and ozone profiles retrieved from GOME-2 and their validation |
| VerfasserIn |
G. M. Miles, R. Siddans, B. J. Kerridge, B. G. Latter, N. A. D. Richards |
| 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 ; 8, no. 1 ; Nr. 8, no. 1 (2015-01-22), S.385-398 |
| Datensatznummer |
250116060
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| Publikation (Nr.) |
 copernicus.org/amt-8-385-2015.pdf |
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| Zusammenfassung |
This paper describes and assesses the performance of the RAL (Rutherford
Appleton Laboratory) ozone profile retrieval scheme for the Global Ozone
Monitoring Experiment 2 (GOME-2) with a focus on tropospheric ozone.
Developments to the scheme since its application to GOME-1 measurements are
outlined. These include the approaches developed to account sufficiently for
UV radiometric degradation in the Hartley band and for inadequacies in
knowledge of instrumental parameters in the Huggins bands to achieve the
high-precision spectral fit required to extract information on tropospheric
ozone.
The assessment includes a validation against ozonesondes (sondes) sampled
worldwide over 2 years (2007–2008). Standard deviations of the ensemble
with respect to the sondes are considerably lower for the retrieved profiles
than for the a priori, with the exception of the lowest subcolumn. Once
retrieval vertical smoothing (averaging kernels) has been applied to the
sonde profiles there is a retrieval bias of 6% (1.5 DU) in the lower
troposphere, with smaller biases in the subcolumns above. The bias in the
troposphere varies with latitude. The retrieval underestimates lower
tropospheric ozone in the Southern Hemisphere (SH) (15–20% or
~ 1–3 DU) and overestimates it in the Northern Hemisphere (NH)
(10% or 2 DU).
The ability of the retrieval to reflect the geographical distribution of
lower tropospheric ozone, globally (rather than just ozonesonde launch sites)
is demonstrated by comparison with the chemistry transport model TOMCAT. For
a monthly mean of cloud-cleared GOME-2 pixels, a correlation of 0.66 is found
between the retrieval and TOMCAT sampled accordingly, with a bias of
0.7 Dobson Units. GOME-2 estimates higher concentrations in NH pollution
centres but lower ozone in the Southern Ocean and South Pacific, which is
consistent with the comparison to ozonesondes. |
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