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| Titel |
Mesoscale energetics and flows induced by sea-land and mountain-valley contrasts |
| VerfasserIn |
S. Federico, G. A. Dalu, C. Bellecci, M. Colacino |
| 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 ; 18, no. 2 ; Nr. 18, no. 2, S.235-246 |
| Datensatznummer |
250013912
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| Publikation (Nr.) |
 copernicus.org/angeo-18-235-2000.pdf |
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| Zusammenfassung |
We study the relative importance of sea-land
and mountain-valley thermal contrasts in determining the development of
thermally forced mesoscale circulations (TFMCs) over a mountainous peninsula. We
first analyse the energetics of the problem, and using this theory, we
interprete the numerical simulations over Calabria, a mountainous peninsula in
southern Italy. The CSU 3-D nonlinear numerical model is utilised to simulate
the dynamics and the thermodynamics of the atmospheric fields over Calabria.
Results show the importance of orography in determining the pattern of the flow
and the local climate in a region as complex as Calabria. Analysis of the
results shows that the energetics due to the sea-land interactions are more
efficient when the peninsula is flat. The importance of the energy due to the
sea-land decreases as the mountain height of the peninsula increases. The energy
stored over the mountain gains in importance, untill it is released by the
readjustment of the warm mountain air as it prevails over the energy released by
the inland penetration of the sea breeze front. For instance, our results show
that over a peninsula 100 km wide the energy over the mountain and the energy in
the sea-land contrast are of the same order when the height of the mountain is
about 700 m, for a 1500 m convective boundary layer (CBL) depth. Over the
Calabrian peninsula, the energy released by the hot air in the CBL of the
mountain prevails over the energy released by the inland penetration of the sea
air. Calabria is about 1500 m high and about 50 km wide, and the CBL is of the
order of 1500 m. The energy over the mountain is about four time larger than the
energy contained in the sea-land contrast. Furthermore, the energetics increase
with the patch width of the peninsula, and when its half width is much less than
the Rossby radius, the MAPE of the sea breeze is negligible. When its half width
is much larger than the Rossby radius, the breezes from the two opposing
coastlines do not interact. Over Calabria peninsula, numerical simulations show
that the flow is highly ageostrophic, and that the flow intensity increases from
sunrise to reach its maximum in the afternoon but before sunset, which suggests
that, in the late part of the day, the conversion of potential energy into
kinetic energy is balanced by the dissipation.
Key words: Meteorology and atmospheric dynamics (climatology;
mesoscale meteorology) |
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