Spatial and temporal distribution of precipitation in a Mediterranean area (southern Italy)

The precipitation climate regime of a region is characterized by the distribution of the monthly precipitation contribution. Its temporal and spatial analysis is particularly interesting for many fields of applied sciences, such as climatology, hydrology and water resources management. With the aim to describe the climate regime, its spatial feature and relevant potential temporal shift, for a large area of southern Italy (Mediterranean basin), a database of about 559 stations has been explored through the statistical analysis of rainfall time series spanning between 1917-2006. After a change point analysis, aimed at the assessment of data quality, a trend analysis has been performed on both monthly precipitation, monthly percentage of annual rainfall amount and PCI-computed series. The broad extension of the area under investigation highlights a better understanding of precipitation distribution patterns over space. Results of PCI trend analysis show a significant shift, for about 40%-50% of total gauging station, over the time toward a more uniform climate regime, especially for the hilly areas. Moreover, the trend analysis on the monthly rainfall series indicate that the shift is produced by a reduction of rainfall amount during the winter season, particular consistent over the Tyrrhenian side of the peninsula, and an increase during the summer season quite widespread over the whole investigated territory.