Advances in Geosciences
www.adv-geosci.net
1680-7340
1680-7359
12
Mediterranean storms and extreme events in an era of climate change
2007
10.5194/adgeo-12-5-2007
http://www.adv-geosci.net/12/5/2007/
http://www.adv-geosci.net/12/5/2007/adgeo-12-5-2007.html
http://www.adv-geosci.net/12/5/2007/adgeo-12-5-2007.pdf
5
18
2007-06-26
Predictability of intense rain storms in the Central Mediterraneanbasin: sensitivity to upper-level forcing
S. Federico
s.federico@crati.it
E. Avolio
C. Bellecci
A. Lavagnini
R. L. Walko
CRATI Scrl, c/o Università della Calabria, Rende (CS), Italy
CNR-ISAC, via del Fosso del Cavaliere 100, Rome , Italy
Facoltà di Ingegneria-Università di "Tor Vergata", via del Politecnico 1, Rome , Italy
Pratt School, Duke University, Durham, NC, USA
This study investigates the sensitivity of a moderate-intense storm that
occurred over Calabria, southern Italy, to upper-tropospheric forcing from a
Potential Vorticity (PV) perspective. A prominent mid-troposheric trough can
be identified for this event, which occurred between 22–24 May 2002, and
serves as the precursor agent for the moderate-intense precipitation
recorded.
<br><br>
The working hypothesis is that the uncertainty in the representation of the
upper-level disturbance has a major impact on the precipitation forecast and
we test the hypothesis in a two-step approach. First, we examine the degree
of uncertainty by comparing five different scenarios in a Limited area model
Ensemble Prediction System (LEPS) framework which utilizes the height of the
dynamical tropopause as the discriminating variable. Pseudo water vapour
images of different scenarios are compared to the corresponding METEOSAT 7
water vapour image at a specific time, antecedent to the rain occurrence
over Calabria, in order to evaluate the reliability of the different
precipitation scenarios simulated by the LEPS.
<br><br>
Second, we examine the impact of upper tropospheric PV variations on
precipitation by comparing model simulations with slightly different initial
PV fields. Initial velocity and mass fields in each case are balanced with
the chosen PV perturbation using a PV inversion technique. The results of
this study support the working hypothesis.
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