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| Titel |
Improvement of OMI ozone profile retrievals in the upper troposphere and lower stratosphere by the use of a tropopause-based ozone profile climatology |
| VerfasserIn |
J. Bak, X. Liu, J. C. Wei, L. L. Pan, K. Chance, J. H. Kim |
| 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 ; 6, no. 9 ; Nr. 6, no. 9 (2013-09-03), S.2239-2254 |
| Datensatznummer |
250085052
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| Publikation (Nr.) |
 copernicus.org/amt-6-2239-2013.pdf |
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| Zusammenfassung |
| Motivated by the need of obtaining a more accurate global ozone distribution
in the upper troposphere and lower stratosphere (UTLS), we have investigated
the use of a tropopause-based (TB) ozone climatology in ozone profile
retrieval from the Ozone Monitoring Instrument (OMI). Due to the limited
vertical ozone information in the UTLS region from OMI backscattered
ultraviolet radiances, better climatological a priori information is
important for improving ozone profile retrievals. We present the new TB
climatology and evaluate the result of retrievals against previous work. The
TB climatology is created using ozonesonde profiles from 1983 through 2008
extended with climatological ozone data above sonde burst altitude
(~35 km) with the corresponding temperature profiles used to
identify the thermal tropopause. The TB climatology consists of the mean
states and 1σ standard deviations for every month for each 10°
latitude band. Compared to the previous TB climatology by Wei et al. (2010),
three additional processes are applied in deriving our climatology:
(1) using a variable shifting offset to define the TB coordinate, (2) separating
ozonesonde profiles into tropical and extratropical regimes based on a
threshold of 14 km in the thermal tropopause height, and (3) merging with an
existing climatology from 5–10 km above the tropopause. The first process
changes the reference of profiles to a variable position between local and
mean tropopause heights within ±5 km of the tropopause and to the
mean tropopause elsewhere. The second helps to preserve characteristics of
either tropical or extratropical ozone structures depending on tropopause
height, especially in the subtropical region. The third improves the
climatology above ozonesonde burst altitudes and in the stratosphere by
using climatology derived from many more satellite observations of ozone
profiles. With aid from the National Centers for Environmental Prediction
(NCEP) Global Forecast System (GFS) tropopause height, the new climatology
and retrieval can better represent the dynamical variability of ozone in the
tropopause region. The new retrieval result demonstrates significant
improvement of UTLS ozone, especially in the extratropical UTLS, when
evaluated using ozonesonde measurements and the meteorological data. The use
of TB climatology significantly enhances the spatial consistency and the
statistical relationship between ozone and potential vorticity/tropopause
height in the extratropical UTLS region. Comparisons with ozonesonde
measurements show substantial improvements in both mean biases and their
standard deviations over the extratropical lowermost stratosphere and upper troposphere.
Overall, OMI retrievals with the TB climatology show improved ability in
capturing ozone gradients across the tropopause found in
tropical/extratropical ozonesonde measurements. |
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