Trends in High Frequency Precipitation Variability in Some Northern Italy Secular Stations

Recent studies on changes in precipitation intensity have found for some areas evidence of an increase in the proportion of total precipitation contributed by heavy and extreme rainfall events in the last 80 years. The purpose of the paper is to verify whether such a signal can also be detected in Northern Italy where daily precipitation (DP) is available starting from the beginning of the 19’ century. The analysis is performed on 5 stations: Genoa (1833–1998), Milan (1858–1998), Mantova (1868–1997), Bologna (1879–1998) and Ferrara (1879–1996). It gives evidence that in Northern Italy there is a positive trend in the proportion of total precipitation contributed by heavy precipitation events (i.e. DP > 25 mm and DP > 50 mm). The trend is mainly caused by the last 60–80 years and is particularly evident in the periods 1930–1960 and 1975–1995. It is more evident in the western than in the eastern area.