Measure of the long-range persistence of solar irradiance signals using the fractal dimension

This article deals with fractal analysis of global solar irradiation signals in view to quantify there long range persistence. For this purpose, a new method to measure the fractal dimension of temporal discrete signals ¿rectangular covering method¿ is presented. The fractal dimension is then used as criterion in an approach we have elaborated to detect the long term correlation in solar irradiation series. The methodology has been applied to annual global irradiation signals of USA sites measured at different latitudes and longitudes. The results show that annual solar irradiation signals are anti-persistent. This is means that irradiations are negatively correlated at long-range.