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| Titel |
Solar response in tropical stratospheric ozone: a 3-D chemical transport model study using ERA reanalyses |
| VerfasserIn |
S. Dhomse, M. P. Chipperfield, W. Feng, J. D. Haigh |
| 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 ; 11, no. 24 ; Nr. 11, no. 24 (2011-12-16), S.12773-12786 |
| Datensatznummer |
250010277
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| Publikation (Nr.) |
 copernicus.org/acp-11-12773-2011.pdf |
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| Zusammenfassung |
| We have used an off-line 3-D chemical transport model (CTM) to investigate
the 11-yr solar cycle response in tropical stratospheric ozone. The model
is forced with European Centre for Medium-Range Weather Forecasts (ECMWF)
(re)analysis (ERA-40/operational and ERA-Interim) data for the 1979–2005 time
period. We have compared the modelled solar response in ozone to
observation-based data sets that are constructed using satellite instruments
such as Total Ozone Mapping Spectrometer (TOMS), Solar Backscatter
UltraViolet instrument (SBUV), Stratospheric Aerosol and Gas Experiment
(SAGE) and Halogen Occultation Experiment (HALOE). A significant difference
is seen between simulated and observed ozone during the 1980s, which is
probably due to inhomogeneities in the ERA-40 reanalyses. In general, the
model with ERA-Interim dynamics shows better agreement with the observations
from 1990 onwards than with ERA-40. Overall both standard model simulations
are partially able to simulate a "double peak"-structured ozone solar
response with a minimum around 30 km, and these are in better agreement with
HALOE than SAGE-corrected SBUV (SBUV/SAGE) or SAGE-based data sets. In the
tropical lower stratosphere (TLS), the modelled solar response with
time-varying aerosols is amplified through aliasing with a volcanic signal,
as the model overestimates ozone loss during high aerosol loading years.
However, the modelled solar response with fixed dynamics and constant
aerosols shows a positive signal which is in better agreement with SBUV/SAGE
and SAGE-based data sets in the TLS. Our model simulations suggests that
photochemistry contributes to the ozone solar response in this region. The
largest model-observation differences occur in the upper stratosphere where
SBUV/SAGE and SAGE-based data show a significant (up to 4%) solar
response
whereas the standard model and HALOE do not. This is partly due to a positive
solar response in the ECMWF upper stratospheric temperatures which reduces
the modelled ozone signal. The large positive upper stratospheric solar
response seen in SBUV/SAGE and SAGE-based data can be reproduced in model
runs with fixed dynamical fields (i.e. no inter-annual meteorological
changes). As these runs effectively assume no long-term temperature changes
(solar-induced or otherwise), it should provide an upper limit of the ozone
solar response. Overall, full quantification of the solar response in
stratospheric ozone is limited by differences in the observed data sets and
by uncertainties in the solar response in stratospheric temperatures. |
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