Evidence of cyclic behaviour in historical rainfall statistics in Milan

We show that significant quasi-periodic cycles are present in century-long rain rate experimental statistics in Milan (Italy): a) in the number of rainy days in a year; b) in the average duration of daily rainy time and average duration of rain events, and in 1-min rain rate complementary probability distributions (pds, for short), obtained by de-integrating historical time series of daily rainfall pds with a recently published de-integration theory. An FFT analysis shows that significant power is at periods of 14.0, 16.0, 21.0 29.0, 41.0 years. The cyclic nature of rain rate is clearly evident in the time series of 1-min rain rate exceeded annually with probability (fraction of time) 1%, 0.1%, 0.01%. The impact on communication design is direct because rain attenuation pds follow the same trend. Future work should concern other localities and the potential use of these results for predicting 1-min rain rate pds.