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| Titel |
Global OZone Chemistry And Related trace gas Data records for the Stratosphere (GOZCARDS): methodology and sample results with a focus on HCl, H2O, and O3 |
| VerfasserIn |
L. Froidevaux, J. Anderson, H.-J. Wang, R. A. Fuller, M. J. Schwartz, M. L. Santee, N. J. Livesey, H. C. Pumphrey, P. F. Bernath, J. M. Russell, M. P. McCormick |
| 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 ; 15, no. 18 ; Nr. 15, no. 18 (2015-09-24), S.10471-10507 |
| Datensatznummer |
250120047
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| Publikation (Nr.) |
 copernicus.org/acp-15-10471-2015.pdf |
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| Zusammenfassung |
We describe the publicly available data from the Global OZone Chemistry And Related trace gas Data records for the Stratosphere (GOZCARDS) project and provide some
results, with a focus on hydrogen chloride (HCl), water vapor (H2O),
and ozone (O3). This data set is a global long-term stratospheric Earth
system data record, consisting of monthly zonal mean time series starting as
early as 1979. The data records are based on high-quality measurements from
several NASA satellite instruments and the Atmospheric Chemistry
Experiment Fourier Transform Spectrometer (ACE-FTS) on SCISAT. We examine
consistency aspects between the various data sets. To merge ozone records,
the time series are debiased relative to SAGE II (Stratospheric
Aerosol and Gas Experiments) values by calculating
average offsets versus SAGE II during measurement overlap periods, whereas
for other species the merging derives from an averaging procedure during
overlap periods. The GOZCARDS files contain mixing ratios on a common
pressure–latitude grid, as well as standard errors and other diagnostics; we
also present estimates of systematic uncertainties in the merged products.
Monthly mean temperatures for GOZCARDS were also produced, based directly on
data from the Modern-Era Retrospective analysis for Research and
Applications.
The GOZCARDS HCl merged product comes from the Halogen Occultation
Experiment (HALOE), ACE-FTS and lower-stratospheric Aura Microwave Limb Sounder (MLS) data. After a rapid rise in upper-stratospheric HCl
in the early 1990s, the rate of decrease in this region for 1997–2010 was
between 0.4 and 0.7 % yr−1. On 6–8-year timescales, the rate of decrease
peaked in 2004–2005 at about 1 % yr−1, and it has since levelled off, at
~ 0.5 % yr−1. With a delay of 6–7 years, these changes roughly
follow total surface chlorine, whose behavior versus time arises from
inhomogeneous changes in the source gases. Since the late 1990s, HCl
decreases in the lower stratosphere have occurred with pronounced
latitudinal variability at rates sometimes exceeding 1–2 % yr−1. Recent
short-term tendencies of lower-stratospheric and column HCl vary
substantially, with increases from 2005 to 2010 for northern midlatitudes and
deep tropics, but decreases (increases) after 2011 at northern (southern)
midlatitudes.
For H2O, the GOZCARDS product covers both stratosphere and mesosphere,
and the same instruments as for HCl are used, along with Upper Atmosphere Research Satellite (UARS) MLS
stratospheric H2O data (1991–1993). We display seasonal to decadal-type
variability in H2O from 22 years of data. In the upper mesosphere, the
anticorrelation between H2O and solar flux is now clearly visible over
two full solar cycles. Lower-stratospheric tropical H2O has exhibited
two periods of increasing values, followed by fairly sharp drops (the
well-documented 2000–2001 decrease and a recent drop in 2011–2013). Tropical
decadal variability peaks just above the tropopause. Between 1991 and 2013,
both in the tropics and on a near-global basis, H2O has decreased by
~ 5–10 % in the lower stratosphere, but about a 10 %
increase is observed in the upper stratosphere and lower mesosphere.
However, such tendencies may not represent longer-term trends.
For ozone, we used SAGE I, SAGE II, HALOE, UARS and Aura MLS, and ACE-FTS
data to produce a merged record from late 1979 onward, using SAGE II as the
primary reference. Unlike the 2 to 3 % increase in near-global column
ozone after the late 1990s reported by some, GOZCARDS stratospheric column
O3 values do not show a recent upturn of more than 0.5 to 1 %;
long-term interannual column ozone variations from GOZCARDS are generally in
very good agreement with interannual changes in merged total column ozone
(Version 8.6) data from SBUV instruments.
A brief mention is also made of other currently available,
commonly formatted GOZCARDS satellite data records for stratospheric
composition, namely those for N2O and HNO3. |
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