Advances in Geosciences www.adv-geosci.net 1680-7340 1680-7359 16 Observation, Prediction and Verification of Precipitation (EGU Session 2007) 2008 10.5194/adgeo-16-125-2008 http://www.adv-geosci.net/16/125/2008/ http://www.adv-geosci.net/16/125/2008/adgeo-16-125-2008.html http://www.adv-geosci.net/16/125/2008/adgeo-16-125-2008.pdf 125 129 2008-04-09 Preliminary study of an intense rainfall episode in Corsica, 14 September 2006 D. Lambert dominique.lambert@aero.obs-mip.fr S. Argence Laboratoire d'Aérologie, CNRS-UPS, Toulouse, France A preliminary study of the 14 September 2006 heavy rainfall episode in Corsica is presented. Two sets of initial and coupling fields were used to run the French non-hydrostatic mesoscale model, MESO-NH. Three interactive 2-way nested domains were used, having 150×120, 150×150 and 125×200 grid points and 50 km, 10 km and 2 km mesh sizes. 50 vertical levels were defined. From ground level to 2000 m, the vertical resolution was 60 m, whereas it was 600 m above. Convection was parameterized for the coarser and intermediate domains and assumed to be explicitly resolved for the 2 km grid. At large scale, the situation is well represented by both simulations but, at the fine scale, they present significant differences. Comparison with the observations did not allow the two simulations to be discriminated. Even though the main high-level dynamical ingredients usually associated with rain storms were present in both simulations, their fine scale evolution was not reproduced well. Near the surface, there were significant differences between the two simulations. Vertical motion fields associated with convective phenomena were different in the innermost domain. A cold pool acting as a warm front off the east coast was associated with the main rainfall area over the sea in one simulation whereas in the second one, it seemed that the Corsican mountains acted as a barrier, leading to inland rainfall. This preliminary study gives perspectives for future sensitivity tests. For example, an investigation is planned of the influence of the high level dynamics, the SST and a better description of the orography. Argence, S., Lambert, D., Richard, E., Söhne, N., Chaboureau, J.-P., Crépin, F., and Arbogast, P.: High resolution numerical study of the Algiers 2001 flash flood: sensitivity to the upper-level potential vorticity anomaly, Adv. Geosci., 7, 251–257, 2006. Chaigne, E. and Arbogast, P.: Multiple potential vorticity inversions in two FASTEX cyclones, Q. J. R. Meteorol. Soc., 126, 1711–1734, 2000. Lafore, J.-P., Stein, J., Bougeault, P., Ducrocq, V., Duron, J., Fisher, C., Hereil, P., Mascart, P., Masson, V., Pinty, J.-P., Redelsperger, J.-L., Richard, E., and Vila-Guerau de Arellano, J.: The Meso-NH atmospheric simulation system. Part I: adiabatic formulation and control simulations, Ann. Geophys., 16, 90–109, 1998. Lambert, D., Arbogast, P., Cammas, J.-P., Donnadille, J., and Mascart, P.: A cold air cyclogenesis study using potential vorticity inversion method, Q. J. R. Meteorol. Soc., 130, 2953–2970, 2004. Lebeaupin, C., Ducrocq, V., and Giordani, H.: Sensitivity of torrential rain events to the sea surface temperature based on high-resolution numerical forecasts, J. Geophys. Res., 111, D12110, doi:10.1029/2005JD006541, 2006. Nuissier, O., Ducrocq, V., Ricard, D., Lebeaupin, C., and Anquetin, S.: A numerical study of three catastrophic precipitating events over Southern France, Part I: Numerical framework and synoptic ingredients, Q. J. R. Meteorol. Soc., in press, 2007. Pettersen, S.: Weather analysis and forecasting, McGraw-Hill, New-York, 428 pp., 1956.