Analysis of rainfall trend in southern Italy through the application of the ITA technique

In the last decades, climate change has been the focus of considerable international attention due to the increase of phenomena such as flood, heat waves, forest fires and droughts. In this context, research on the patterns of precipitation trends, both at regional and local scale, has been paramount because these variations can negatively impact on ecosystems, agriculture, water supply and management, human welfare and regional political stability. In this paper, an investigation of the temporal rainfall variability has been carried out using a homogeneous monthly rainfall dataset of 559 rain gauges with more than 50 years of observation. The region under investigation is a large portion of the Italian peninsula, ranging from the Campania and the Apulia regions in the North, to Sicily in the South, and covering an area of about 85,000 km2. Possible trends in monthly and seasonal rainfall values have been investigated by means of a new graphical methodology (Innovative Trend Analysis), which allows the trend identification of the low, medium and high values of a series. As a result, different values and tendencies of the highest and the lowest rainfall values have emerged among the five regions considered in the analysis. Especially at seasonal scale, a negative trend has been detected in winter and in autumn in the whole study area, whereas not well defined trend signals have been identified in summer and spring.