Most intense ARs

A detection algorithm, designed for the open oceans (Guan and Waliser, 2015), has been adapted to the peculiar complex morphology of the Mediterranean region. It has been applied to conduct a climatological analysis on the presence of atmospheric rivers in the Mediterranean, exploiting ERA5 reanalysis. ARs affecting northern-central Italy have been detected from 1960 to 2024. The methodology is explained in details in Davolio et al. (2025).

To assess the relationship of ARs with extreme rainfall events, ArCIS precipitation dataset (Pavan et al, 2019) has been exploited. This is a high-resolution (5 x 5 km) gridded dataset  derived from the interpolation of a high-density surface observation network, consisting of more than 1700 raingauges distributed on 11 Italian regions, and includes also several stations of adjacent Alpine regions. 

In the following, a preliminary analysis ranks the identified AR events in order of intensity, based on the maximum IVT value (exceeding 1000 kg/m/s !!) attained just offshore the Italian coast. All the most intense ARs are associated with very intense, sometimes extreme, precipitation events and severe impacts on the affected areas, thus indicating that extreme transport of humidity from remote areas leads to extreme rainfall and floods, and represents an important diagnostic to take into account also for forecasting purposes.