ADGEO Advances in Geosciences ADGEO 1680-7359 Copernicus GmbH Göttingen, Germany 10.5194/adgeo-16-125-2008 Preliminary study of an intense rainfall episode in Corsica, 14 September 2006 Lambert D. 1 Argence S. 1 Laboratoire d'Aérologie, CNRS-UPS, Toulouse, France 09 04 2008 16 16 125 129 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.adv-geosci.net/16/125/2008/adgeo-16-125-2008.html The full text article is available as a PDF file from http://www.adv-geosci.net/16/125/2008/adgeo-16-125-2008.pdf

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.

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