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The investigation of the spatial correlation structure exhibited by ground-based rainfall measurements can provide useful results for understanding, from a climatic point of view, the effects produced by the interaction between meteorological patterns and morphological features of a given territory. The central aspect of this study is the description of the spatial inhomogeneity and anisotropy that characterizes the correlation structure of daily rainfall. In the proposed approach, the analysis is developed by assuming that the correlation structure exhibited by the rainfall heights can be interpreted through a suitable deformation of the spatial coordinates providing a homogeneous and isotropic field. The technique has been applied to the daily rainfall recorded at the rain gauges network of the Crati River basin (Southern Italy). The results show that the elliptic deformations of the spatial structure exhibited by the correlation structure of the rain gauges are closely related to the physiographic features of the territory. [ABSTRACT FROM AUTHOR]

Seasonal rainfall amounts, directly responsible for availability of water resources on a specified area, are strongly dependent on the climate system. In order to highlight some features of such dependence, generally circulation indexes based on the difference in the sea level pressure between two geographic areas are taken into account. In the present study, the relationships between winter rainfall series observed in the Calabria region (southern Italy) and the North Atlantic Oscillation Index (NAOI) have been analysed. Firstly, a correlation analysis between precipitation and the NAOI was performed. Subsequently, the influence of the different phases of the NAO on the winter precipitation has been detected by a composite analysis, and by identifying changes in the behaviour of the probability density functions (gamma distribution) fitted on monthly rainfall. The results evidence a clear link existing between the phases of the climatic index and the amount of winter rainfall. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]