Decline in Mediterranean rainfall caused by weakening of Mediterranean cyclones

Abstract

Wet season (October-March) rainfall over the Northern Mediterranean has decreased over the last four decades. The decline is being forced locally by a decrease in the intensity of cyclogenesis events in the region. The forcing is subtle, since overall cyclone frequency exhibits no significant trend over time. The reduction in strength of the most intense cyclones is driven by recent trends observed in the coupled ocean-atmospheric circulation over the Northern Atlantic, in particular by the northwards migration of the main Atlantic storm-tracks.