Analysis of convective situations over the Alps during the MAP SOP

The goal of this presentation is to discuss the ingredients of heavy precipitations over the Alps during the whole MAP SOP (Lin et al 2001). The 3D VAR Arpege system, operational during the MAP SOP, is used to provide the analyzed fields every 6 hours. From these informations, regional averages provide quantitative informations which are correlated to the rain intensity provided by the Frei and Haeller(2001).

These informations have been also deduced from another analysis system (i.e. the IFS system of ECMWF) and from simulated fields (Meso-NH simulation) and compared to the Arpege analysis in order to test the stability of the conclusion on the IOP 2B case.

Among the different tested ingredients, the most important ones are the intensity of the low level mosture flux over the Mediterranean Sea, the PV anomaly position and intensity.Q vector diagnostics have also been used in order to document the impact of the entrance and exit of jets flowing over the Alps on the convection triggering. Finally a conceptual model of dangerous situations, deduced from this study, will be presented.