Wavelet analisys as a tool for characterizing trend in climatic data

Wavelet transform is an effective mathematical tool able to provide a time—frequency representation of signals defined in the time domain. So far this innovative multiscale analysis has been successfully applied in various fields of science, such as, for example, geophysics, astrophysics, telecommunications and climatology. In this chapter the wavelet analysis is employed to analyse Sicily temperature data. Sicily represents one of the hot spot for the study of climate change in the Mediterranean area, because of its vulnerability to desertification processes. Precipitations and temperature trends forecasted for the XXI century by Regional Climate Models (RCM) show an increasing temperature trend and a non-clear precipitation trend. To better characterize the temperature trend, the 1865-2016 temperature time series of Palermo and the 1962-2014 time series of four Sicilian localities have been analysed by means of Continue and Discrete Wavelet Transforms. Such analyses allow to identify the fast and slow events contained in the time series and to identify the major features of the Sicilian climate dynamics.