Periodicity Study of Erythemal Ultraviolet-B Radiation Data over Egypt

Periodicity of the daily and mean monthly values of ErythemalUV-B radiation of the stations El-Arish, Aswan, Hurghada andSouth Valley has been examined. The harmonic analysis has been appliedto study the variations of the daily and monthly time series ofErythemal UV-B radiation of these four stations. Results revealed thatthe dominant waves that appeared with the analysis of the daily timeseries of the four stations were 13, 13.5, 13.4, 13.4 months respectively.The analysis of the mean monthly values for the four stationsshowed that the dominant wave in these four time series was theannual wave with high statistically significant results. These annualwaves were used in forecasting UV-B radiation for these stations.