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| Titel |
Evaluation of the use of five laboratory-determined ozone absorption cross sections in Brewer and Dobson retrieval algorithms |
| VerfasserIn |
A. Redondas, R. Evans, R. Stuebi, U. Köhler, M. Weber |
| 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 ; 14, no. 3 ; Nr. 14, no. 3 (2014-02-12), S.1635-1648 |
| Datensatznummer |
250118372
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| Publikation (Nr.) |
 copernicus.org/acp-14-1635-2014.pdf |
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| Zusammenfassung |
The primary ground-based instruments used to report total column ozone (TOC)
are Brewer and Dobson spectrophotometers in separate networks. These
instruments make measurements of the UV irradiances, and through a
well-defined process, a TOC value is produced. Inherent to the algorithm is
the use of a laboratory-determined cross-section data set. We used five ozone
cross-section data sets: three data sets that are based on measurements of
Bass and Paur; one derived from Daumont, Brion and Malicet (DBM); and a new
set determined by Institute of Experimental Physics (IUP), University of
Bremen.
The three Bass and Paur (1985) sets are as follows: quadratic temperature coefficients from
the IGACO (a glossary is provided in Appendix A) web page (IGQ4), the Brewer
network operational calibration set (BOp), and the set used by
Bernhard et al. (2005) in the reanalysis of the Dobson absorption
coefficient values (B05). The ozone absorption coefficients for Brewer and
Dobson instruments are then calculated using the normal Brewer operative
method, which is essentially the same as that used for Dobson instruments.
Considering the standard TOC algorithm for the Brewer instruments and
comparing to the Brewer standard operational calibration data set, using the
slit functions for the individual instruments, we find the IUP data set
changes the calculated TOC by −0.5%, the DBM data set changes the
calculated TOC by −3.2%, and the IGQ4 data set at −45 °C changes the calculated TOC by +1.3%.
Considering the standard algorithm for the Dobson instruments, and comparing
to results using the official 1992 ozone absorption coefficients values and
the single set of slit functions defined for all Dobson instruments, the
calculated TOC changes by +1%, with little variation depending on which
data set is used.
We applied the changes to the European Dobson and Brewer reference
instruments during the Izaña 2012 Absolute Calibration Campaign. With the
application of a common Langley calibration and the IUP cross section, the
differences between Brewer and Dobson data sets vanish, whereas using those
of Bass and Paur and DBM produces differences of 1.5 and 2%, respectively.
A study of the temperature dependence of these cross-section data sets is
presented using the Arosa, Switzerland, total ozone record of 2003–2006,
obtained from two Brewer-type instruments and one Dobson-type instrument,
combined with the stratospheric ozone and temperature profiles from the
Payerne soundings in the same period. The seasonal dependence of the
differences between the results from the various instruments is greatly
reduced with the application of temperature-dependent absorption
coefficients, with the greatest reduction obtained using the IUP data set. |
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