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| Titel |
Copernicus stratospheric ozone service, 2009–2012: validation, system intercomparison and roles of input data sets |
| VerfasserIn |
K. Lefever, R. van der A, F. Baier, Y. Christophe, Q. Errera, H. Eskes, J. Flemming, A. Inness, L. Jones, J.-C. Lambert, B. Langerock, M. G. Schultz, O. Stein, A. Wagner, S. Chabrillat |
| 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. 5 ; Nr. 15, no. 5 (2015-03-03), S.2269-2293 |
| Datensatznummer |
250119483
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| Publikation (Nr.) |
 copernicus.org/acp-15-2269-2015.pdf |
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| Zusammenfassung |
This paper evaluates and discusses the quality of the stratospheric ozone
analyses delivered in near real time by the MACC (Monitoring
Atmospheric Composition and Climate) project during the 3-year
period between September 2009 and September 2012. Ozone analyses
produced by four different chemical data assimilation (CDA) systems
are examined and compared: the Integrated Forecast
System coupled to the Model for OZone And Related chemical Tracers (IFS-MOZART);
the Belgian Assimilation System for Chemical ObsErvations (BASCOE);
the Synoptic Analysis of Chemical Constituents by Advanced Data
Assimilation (SACADA); and the Data Assimilation Model based on
Transport Model version 3 (TM3DAM). The assimilated satellite ozone
retrievals differed for each system; SACADA and TM3DAM assimilated
only total ozone observations, BASCOE assimilated profiles for ozone
and some related species, while IFS-MOZART assimilated both types of
ozone observations.
All analyses deliver total column values that agree well with ground-based
observations (biases < 5%) and have a realistic seasonal cycle,
except for BASCOE analyses, which underestimate total ozone in the tropics
all year long by 7 to 10%, and SACADA analyses, which overestimate
total ozone in polar night regions by up to 30%.
The validation of the vertical distribution is based on
independent observations from ozonesondes and the
ACE-FTS (Atmospheric Chemistry Experiment – Fourier Transform
Spectrometer) satellite instrument. It cannot be performed with
TM3DAM, which is designed only to deliver analyses of total ozone columns.
Vertically alternating positive and negative biases are found in the IFS-MOZART
analyses as well as an overestimation of 30 to 60% in the polar
lower stratosphere during polar ozone depletion events.
SACADA underestimates lower stratospheric ozone by up to 50%
during these events above the South Pole and
overestimates it by approximately the same amount in the tropics.
The three-dimensional (3-D) analyses delivered by BASCOE are found to have
the best quality among the three systems resolving the vertical dimension,
with biases not exceeding 10% all year long, at all stratospheric levels and
in all latitude bands, except in the tropical lowermost stratosphere.
The northern spring 2011 period is studied in more detail to evaluate the
ability of the analyses to represent the exceptional ozone depletion event,
which happened above the Arctic in March 2011.
Offline sensitivity tests are performed during this month and
indicate that the differences between the forward models or the assimilation
algorithms are much less important than the characteristics of the
assimilated data sets. They also show that IFS-MOZART is able to
deliver realistic analyses of ozone both in the troposphere and
in the stratosphere, but this requires the assimilation of observations
from nadir-looking instruments as well as the assimilation of
profiles, which are well resolved vertically and extend into
the lowermost stratosphere. |
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