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| Titel |
The coupled chemistry-climate model LMDz-REPROBUS: description and evaluation of a transient simulation of the period 1980-1999 |
| VerfasserIn |
L. Jourdain, S. Bekki, F. Lott, F. Lefèvre |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 26, no. 6 ; Nr. 26, no. 6 (2008-06-11), S.1391-1413 |
| Datensatznummer |
250016113
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| Publikation (Nr.) |
 copernicus.org/angeo-26-1391-2008.pdf |
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| Zusammenfassung |
| We present a description and evaluation of the Chemistry-Climate Model (CCM)
LMDz-REPROBUS, which couples interactively the extended version of the
Laboratoire de Météorologie Dynamique General Circulation Model
(LMDz GCM) and the stratospheric chemistry module of the REactive Processes
Ruling the Ozone BUdget in the Stratosphere (REPROBUS) model. The transient
simulation evaluated here covers the period 1980–1999. The introduction of
an interactive stratospheric chemistry module improves the model dynamical
climatology, with a substantial reduction of the temperature biases in the
lower tropical stratosphere. However, at high latitudes in the Southern
Hemisphere, a negative temperature bias, that is already present in the GCM
version, albeit with a smaller magnitude, leads to an overestimation of the
ozone depletion and its vertical extent in the CCM. This in turn contributes
to maintain low polar temperatures in the vortex, delay the break-up of the
vortex and the recovery of polar ozone. The latitudinal and vertical
variation of the mean age of air compares favourable with estimates derived
from long-lived species measurements, though the model mean age of air is
1–3 years too young in the middle stratosphere. The model also reproduces
the observed "tape recorder" in tropical total hydrogen
(=H2O+2×CH4), but its propagation is about 30% too fast and
its signal fades away slightly too quickly. The analysis of the global
distributions of CH4 and N2O suggests that the subtropical
transport barriers are correctly represented in the simulation.
LMDz-REPROBUS also reproduces fairly well most of the spatial and seasonal
variations of the stratospheric chemical species, in particular ozone.
However, because of the Antarctic cold bias, large discrepancies are found
for most species at high latitudes in the Southern Hemisphere during the
spring and early summer. In the Northern Hemisphere, polar ozone depletion
and its variability are underestimated in the simulation. |
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