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| Titel |
Impact of a simple parameterization of convective gravity-wave drag in a stratosphere-troposphere general circulation model and its sensitivity to vertical resolution |
| VerfasserIn |
C. Bossuet, M. Déqué, D. Cariolle |
| 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 ; 16, no. 2 ; Nr. 16, no. 2, S.238-249 |
| Datensatznummer |
250013160
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| Publikation (Nr.) |
 copernicus.org/angeo-16-238-1998.pdf |
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| Zusammenfassung |
Systematic westerly biases in the southern
hemisphere wintertime flow and easterly equatorial biases are experienced in the
Météo-France climate model. These biases are found to be much reduced when a
simple parameterization is introduced to take into account the vertical momentum
transfer through the gravity waves excited by deep convection. These waves are
quasi-stationary in the frame of reference moving with convection and they
propagate vertically to higher levels in the atmosphere, where they may exert a
significant deceleration of the mean flow at levels where dissipation occurs.
Sixty-day experiments have been performed from a multiyear simulation with the
standard 31 levels for a summer and a winter month, and with a T42 horizontal
resolution. The impact of this parameterization on the integration of the model
is found to be generally positive, with a significant deceleration in the
westerly stratospheric jet and with a reduction of the easterly equatorial bias.
The sensitivity of the Météo-France climate model to vertical resolution is
also investigated by increasing the number of vertical levels, without moving
the top of the model. The vertical resolution is increased up to 41 levels,
using two kinds of level distribution. For the first, the increase in vertical
resolution concerns especially the troposphere (with 22 levels in the
troposphere), and the second treats the whole atmosphere in a homogeneous way
(with 15 levels in the troposphere); the standard version of 31 levels has 10
levels in the troposphere. A comparison is made between the dynamical aspects of
the simulations. The zonal wind and precipitation are presented and compared for
each resolution. A positive impact is found with the finer tropospheric
resolution on the precipitation in the mid-latitudes and on the westerly
stratospheric jet, but the general impact on the model climate is weak, the
physical parameterizations used appear to be mostly independent to the vertical
resolution.
Key words. Meteorology and atmospheric dynamics ·
Convective processes · Waves and tides |
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