2. Extreme Rainfalls in the Mediterranean Area

A brief survey on the extreme rainfalls in the Mediterranean area has been carried out beginning from the key thermal and pluviometric features of the Mediterranean macroclimate (wet and mild winters – warm and dry summers), passing through the main air masses that influence the basin and coming arriving to the main circulation patterns favourable to extreme rainfall (Atlantic troughs, Mediterranean cyclones, blocking systems). In the final part of the work a statistical climatology of daily extreme rainfall events on the Mediterranean area has been carried out analysing for the period 1973–2010 the extreme events in the whole Mediterranean basin and in the Western and Eastern sub-basins. On the basis of the results, it has been possible to state that the temporal behavior of the relative weight of selected precipitation classes is generally steady on average. Exploring each rainfall class, it has been evidenced only a significant increase of “moderate” events (whole basin) and a meanwhile decrease of “strong” events (West). On the other hand, the observed positive trends of classes “moderate” and “strong” for the East part of the basin should be confirmed by a richer dataset referred to this specific area. Such analysis has highlighted the weaknesses of the historical series currently available in the freely accessible International datasets, pointing up the need of more reliable data sources in terms of time continuity and spatial coverage.