In order to investigate the behaviour of climatic and hydrological variables, several statistical and stochastic techniques are currently applied to time series. In the present study a statistical analysis of annual and seasonal precipitation has been performed over 109 cumulated rainfall series with more than 50 years of data observed in a region of Southern Italy (Calabria). Trend analyses have been made by using both nonparametric (Mann–Kendall test) and parametric (linear regression analysis) procedures. The long historical series of monthly rainfall data employed in this work have been previously processed through a pre‐whitening (PW) technique in order to reduce the autocorrelation of rainfall series and its effects on outcomes of trend detection. The application of the above mentioned procedures has shown a decreasing trend for annual and winter–autumn rainfall and an increasing trend for summer precipitation. Moreover the Mann–Whitney test has been used to evidence the possible change points in the data. The higher percentages of rainfall series show possible year changes during decade 1960–1970 for almost all of the temporal aggregation rainfall. Copyright © 2009 Royal Meteorological Society

The present study aims at improving data availability and quality for the last 80–90 years for daily precipitation in the Calabria region (southern Italy). First, the original database was homogenised and the gaps filled in for 129 daily rain gauges for the 1916–2006 period. Then, precipitation variability and change were evaluated at an adequate spatial resolution. Monthly and annual total precipitation (P), number of wet days (WDs), and precipitation intensity (PI) were calculated for each series. With regard to the monthly total precipitation a general negative trend, albeit not everywhere significant, was detected, in particular for the autumn–winter period, while in summer the tendency was toward an increase in total precipitation. The monthly behaviour of WDs was not very different from that observed for P: a diffuse negative trend was detected in most months, particularly evident and significant in January, with the exception of April and the summer months, for which the tendency was toward an increase. Regarding the PI, a general negative and often significant trend was found for the entire region and for almost all the months, except summer. Attention was also focused on tendencies in the different PI categories, revealing negative trends in high‐intensity categories, especially coming from the winter season.Finally, running trend analysis revealed that the previously discussed tendencies were not persistent throughout the series length, but depended on the period examined. This important aspect should be taken into account when different results based on different time windows are compared. Copyright © 2010 Royal Meteorological Society

This study investigates precipitation variability in five regions of Southern Italy (Campania, Apulia, Basilicata, Calabria and Sicily) using a homogeneous database of about 70 rain gauges with more than 50 years of observation. First, a statistical analysis was performed through the Mann-Kendall non-parametric test in order to determine rainfall the trend on both yearly and seasonal scales. Then, the relationship between the rainfall and some teleconnection pattern indexes was investigated using Spearman's test. The results show remarkable statistically significant negative trends for annual and winter aggregations in most part of the series. Moreover, a strong correlation has emerged between the teleconnection patterns and precipitation in Southern Italy, particularly in winter and on the Tyrrhenian side of the study area.