Annual and seasonal precipitation over Italy from 1961 to 2006

Abstract

Abstract 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. Copyright © 2009 Royal Meteorological Society