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| Titel |
Combined SAGE II–GOMOS ozone profile data set for 1984-2011 and trend analysis of the vertical distribution of ozone |
| VerfasserIn |
E. Kyrölä, M. Laine, V. Sofieva, J. Tamminen, S.-M. Päivärinta, S. Tukiainen, J. Zawodny, L. Thomason |
| 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 ; 13, no. 21 ; Nr. 13, no. 21 (2013-11-04), S.10645-10658 |
| Datensatznummer |
250085784
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| Publikation (Nr.) |
 copernicus.org/acp-13-10645-2013.pdf |
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| Zusammenfassung |
We have studied data from two satellite occultation instruments in order to
generate a high vertical resolution homogeneous ozone time series of 26 yr. The Stratospheric Aerosol and Gas Experiment (SAGE) II solar
occultation instrument and the Global Ozone Monitoring by
Occultation of Stars (GOMOS) instrument measured ozone
profiles in the stratosphere and mesosphere from 1984–2005 and 2002–2012, respectively. Global coverage, good vertical
resolution, and the self-calibrating measurement method make data from these
instruments valuable for the detection of changes in vertical distribution of
ozone over time. As both instruments share a common measurement period from
2002–2005, it is possible to inter-calibrate the data sets. We investigate
how well these measurements agree with each other and combine all the data to
produce a new stratospheric ozone profile data set. Above 55 km, SAGE II
measurements show much less ozone than the GOMOS nighttime measurements as a
consequence of the well-known diurnal variation of ozone in the mesosphere.
Between 35–55 km, SAGE II sunrise and sunset measurements differ from GOMOS' measurements to different extents. Sunrise measurements show 2% less ozone than GOMOS, whereas sunset
measurements show 4% more ozone than GOMOS. Differences can be explained
qualitatively by the diurnal variation of ozone in the stratosphere recently
observed by SMILES and modeled by chemical transport models. Between 25–35 km, SAGE II sunrise and sunset measurements and GOMOS measurements agree within 1%.
The observed ozone bias between collocated measurements of SAGE II
sunrise/sunset and GOMOS night measurements is used to align the two data
sets. The combined data set covers the time period 1984–2011, latitudes
60° S–60° N, and the altitude range of 20–60 km. Profile data are
given on a 1 km vertical grid, and with a resolution of 1 month in time and
10° in latitude. The combined ozone data set is analyzed by fitting a
time series model to the data. We assume a linear trend with an inflection
point (so-called "hockey stick" form). The best estimate for the point of
inflection was found to be the year 1997 for ozone between altitudes 35 and
45 km. At all latitudes and altitudes from 35 to 50 km we find a clear
change in ozone trend before and after the inflection time. From 38 to 45
km, a negative trend of 4% per decade (statistically significant at 95%
level) at the equator has changed to a small positive trend of 0–2% per
decade. At mid-latitudes, the negative trend of 4–8% per decade has changed
to to a small positive trend of 0–2% per decade. At mid-latitudes near 20 km,
the ozone loss has still increased whereas in the tropics a recovery is ongoing. |
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