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| Titel |
A deep cyclone of African origin over the Western Mediterranean: diagnosis and numerical simulation |
| VerfasserIn |
V. Homar, C. Ramis, S. Alonso |
| 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 ; 20, no. 1 ; Nr. 20, no. 1, S.93-106 |
| Datensatznummer |
250014345
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| Publikation (Nr.) |
 copernicus.org/angeo-20-93-2002.pdf |
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| Zusammenfassung |
From 19 to 22 December
1979, a deep cyclone evolved over the Western Mediterranean. Gusty winds of
more than 30 m/s, as well as a strong pressure decrease to about 990 hPa were
recorded in Palma de Mallorca (Balearic Islands, Spain). ECMWF analyses are
used for a diagnosis and numerical study of the case. Sensitivity experiments
using the HIRLAM model are performed to assess the role of the surface sensible
heat flux, latent heat release and orography on the genesis and evolution of
the cyclone. At synoptic scale, the situation is governed by the instability of
an upper-level short wave. The cyclone developed within a notable baroclinic
environment, which resulted from a cold advection from the northwest towards
North Africa. The baroclinicity at first stages of the cyclogenesis is
quantified by means of the Eady model. At latter stages, the evolution of the
potential vorticity structures at high levels reveals a wide tropopause fold
over the cyclone, as well as the presence of a strong anomaly associated with
the low-level system. Sensitivity experiments reveal a notable cyclogenetic
role of the latent heat release throughout the atmosphere in the deepening of
the low, whereas no significant effect of the surface sensible heat flux is
obtained for the simulation interval. On the other hand, an unusual cyclolytic
role can be attributed to the northern ranges of the Mediterranean basin.
Effectively, the low enlargement and deepening is constrained by a "wall
effect", which is a consequence of the interaction of the cyclonic flow
and those northern mountainous systems.
Key words. Meteorology and
atmospheric dynamics (synoptic-scale meteorology, Mesoscale meteorology) |
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