An analysis of Italian seasonal temperatures from 1961 to 2006 was carried out, using homogenized data from 49 synoptic stations well distributed throughout Italy. The results show remarkable differences among seasons. Stationarity characterizes winter series, except for Northern Italy (where a warming trend from 1961 is identified); a positive trend over the entire period is recognized for spring series. Summer series are marked by a negative trend until 1981 and by a positive trend afterwards; finally, autumn series show a warming starting from 1970. The relationship between seasonal temperatures and four teleconnection patterns (North Atlantic Oscillation, East Atlantic Pattern, Scandinavian Pattern and Arctic Oscillation) influencing European climate was investigated through Spearman rank correlation and composites. Among the results, the strong linear correlation with the East Atlantic Pattern in all seasons but autumn is remarkable; moreover, the explained variance varies between 31.9% and 50.4% (leaving out autumn). Besides these four atmospheric patterns the role of other factors (e.g. soil moisture) is not dealt with, but their importance and the need for more investigation is pointed out.

Annual and seasonal precipitation series were derived from a set of 59 synoptic meteorological stations homogeneously distributed over Italy, in order to evaluate possible changes in precipitation behaviour and identifying areas of coherent variability. The time series were homogenized and standardized anomaly series were calculated for three areas: north, centre and south of Italy. Rotated principal component analysis (PCA) was applied to monthly data and the related loading maps were generated. The annual series do not show significant trends, while among the seasonal series only those of winter in northern and central Italy are non-stationary; they are characterized, respectively, by a decreasing trend for the entire period and by a positive trend since 1989. Seven common patterns were identified from clustered rotated principal components and linked with synoptical weather regimes.

Abstract. In Italy, meteorological data necessary and useful for climate studies are collected, processed and archived by a wide range of national and regional institutions. As a result, the density of the stations, the length and frequency of the observations, the quality control procedures and the database structure vary from one dataset to another. In order to maximize the use of those data for climate knowledge and climate change assessments, a computerized system for the collection, quality control, calculation, regular update and rapid dissemination of climate indicators was developed. The products publicly available through a dedicated web site are described, as well as an example of climate trends estimates over Italy, based on the application of statistical models on climate indicators from quality-checked and homogenised time series.