 |
| Titel |
NDACC/SAOZ UV-visible total ozone measurements: improved retrieval and comparison with correlative ground-based and satellite observations |
| VerfasserIn |
F. Hendrick, J.-P. Pommereau, F. Goutail, R. D. Evans, D. Ionov, A. Pazmino, E. Kyrö, G. Held, P. Eriksen, V. Dorokhov, M. Gil, M. Roozendael |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 12 ; Nr. 11, no. 12 (2011-06-24), S.5975-5995 |
| Datensatznummer |
250009869
|
| Publikation (Nr.) |
 copernicus.org/acp-11-5975-2011.pdf |
|
|
|
|
|
| Zusammenfassung |
| Accurate long-term monitoring of total ozone is one of the most important
requirements for identifying possible natural or anthropogenic changes in
the composition of the stratosphere. For this purpose, the NDACC (Network
for the Detection of Atmospheric Composition Change) UV-visible Working
Group has made recommendations for improving and homogenizing the retrieval
of total ozone columns from twilight zenith-sky visible spectrometers. These
instruments, deployed all over the world in about 35 stations, allow
measuring total ozone twice daily with limited sensitivity to stratospheric
temperature and cloud cover. The NDACC recommendations address both the DOAS
spectral parameters and the calculation of air mass factors (AMF) needed for
the conversion of O3 slant column densities into vertical column
amounts. The most important improvement is the use of O3 AMF look-up
tables calculated using the TOMS V8 (TV8) O3 profile climatology, that
allows accounting for the dependence of the O3 AMF on the seasonal and
latitudinal variations of the O3 vertical distribution. To investigate
their impact on the retrieved ozone columns, the recommendations have been
applied to measurements from the NDACC/SAOZ (Système d'Analyse par
Observation Zénithale) network. The revised SAOZ ozone data from eight
stations deployed at all latitudes have been compared to TOMS, GOME-GDP4,
SCIAMACHY-TOSOMI, SCIAMACHY-OL3, OMI-TOMS, and OMI-DOAS satellite overpass
observations, as well as to those of collocated Dobson and Brewer
instruments at Observatoire de Haute Provence (44° N, 5.5° E) and
Sodankyla (67° N, 27° E), respectively. A significantly better
agreement is obtained between SAOZ and correlative reference ground-based
measurements after applying the new O3 AMFs. However, systematic
seasonal differences between SAOZ and satellite instruments remain. These
are shown to mainly originate from (i) a possible problem in the satellite
retrieval algorithms in dealing with the temperature dependence of the ozone
cross-sections in the UV and the solar zenith angle (SZA) dependence, (ii)
zonal modulations and seasonal variations of tropospheric ozone columns not
accounted for in the TV8 profile climatology, and (iii) uncertainty on the
stratospheric ozone profiles at high latitude in the winter in the TV8
climatology. For those measurements mostly sensitive to stratospheric
temperature like TOMS, OMI-TOMS, Dobson and Brewer, or to SZA
like SCIAMACHY-TOSOMI, the application of temperature and SZA corrections
results in the almost complete removal of the seasonal difference with SAOZ,
improving significantly the consistency between all ground-based and
satellite total ozone observations. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|