Ferretti, Rossella (University of L'Aquila)
Lownam, Simon (National Center of Atmospheric Research)
An analysis of the Piedmont flood using the MM5 mesocale model is carried out. Several simulations using different cumulus convections parameterizations (Kerry Emanuel, Grell and Kain-Fritsch) and sensitivity experiments to highlight both the topographic forcing and the role of the latent heat release are performed.
Verification of the Kerry Emanuel cumulus convection parameterization against both Kain-Fritsch , Grell and observations is performed. The amount of precipitation and the areal extent of the KE verify well against observations; soundings also are compared to radiosoundings. Furthermore mesocale disturbances such as surface pressure oscillations are well reproduced by the KE. Strong sensitivity to both latent heat and orography is found. Mechanical lifting by the Alps and diabatic warming are the major contribution to the Piedmont flood. Furthermore the developmnet of low-level PV streamer on the upwind side is clearly related to the diabatic effects as so the circulation on the south west of the Alps which contributes to the confluence of the southwesterly and southeasterly wind.