Natural Hazards and Earth System Science
www.nat-hazards-earth-syst-sci.net
1561-8633
1684-9981
8
1
2008
10.5194/nhess-8-19-2008
http://www.nat-hazards-earth-syst-sci.net/8/19/2008/
http://www.nat-hazards-earth-syst-sci.net/8/19/2008/nhess-8-19-2008.html
http://www.nat-hazards-earth-syst-sci.net/8/19/2008/nhess-8-19-2008.pdf
19
35
2008-01-11
Numerical analysis of an intense rainstorm occurred in southern Italy
S. Federico
s.federico@isac.cnr.it
E. Avolio
C. Bellecci
A. Lavagnini
M. Colacino
R. L. Walko
CNR-ISAC, Strada Prov. Lecce-Monteroni km 1.2, Lecce, Italy
CRATI Scrl, c/o Università della Calabria, Rende (CS), Italy
Facoltà di Ingegneria-Università di "Tor Vergata", via del Politecnico 1, Rome, Italy
CNR-ISAC, Via del Fosso del Cavaliere 100, Rome, Italy
Pratt School, Duke University, Durham, NC, USA
In this study we conduct a numerical analysis of an intense and destructive
storm that occurred over Calabria, southern Italy, on 10–12 December 2003.
More than 250 mm of precipitation was recorded over a large area in southern
Calabria and one station reported about 660 mm in two days (more than half
of the yearly climatological value). Precipitation fell mainly during 11 and
12 December. The storm was characterized by the entrance of an Atlantic
upper-level trough associated with a deep surface low that advected humid
marine air toward steep Calabrian orography. The steep mountain ridges
favoured landslides, which were reported in several villages. Property
damage was extensive.
<br><br>
We study the storm at the mesoscale by means of the Regional Atmospheric
Modeling System (RAMS). The model was successful at representing the
observed accumulated rainfall patterns. This justifies our use of RAMS for
further analysis of the physical and dynamic factors involved in the storm
event. In particular, we use RAMS to evaluate the roles of Calabrian
orography, surface latent heat flux, and upper level forcing.
<br><br>
The key role of a potential vorticity (PV) streamer, which forced the entire
meteorological system from the upper levels is assessed by the PV inversion
technique in a Limited Area Model Ensemble Prediction System (LEPS)
framework.
<br><br>
Results show that the roles of Calabrian orography and surface latent heat
flux are important in our simulations. Indeed, humid marine air masses were
advected by the synoptic flow toward Calabrian steep coastal mountain ranges
determining intense and abundant rainfall.
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