A homogeneous dataset for rainfall trend analysis in the Calabria Region (Southern Italy)

Abstract

In order to investigate the tendency in rainfall amount in Calabria (southern Italy), in this work, monthly rainfall series were first tested for homogeneity and then a trend analysis was performed. In particular, a homogenization approach based on the Climatol method was applied to homogenize monthly climatological series. Then, the Mann-Kendall non-parametric test and the Theil-Sen estimator were applied to evaluate the presence of trends and their significance in the monthly, seasonal and annual rainfall series. Moreover, the trend slopes were further evaluated with a linear regression analysis. At the annual scale, results evidenced a decreasing trend mainly in the north-eastern part of the region. At the seasonal scale, a spatial distributed negative trend in winter, and a positive trend in summer, mainly localized in the north-western part of the region, were identified. Finally, on a monthly scale negative trends spreading across the region were detected in January and December, with an opposite behavior in July and especially in September, when almost the entire region presented a positive trend.