Thee issues concerning the statistics of mean and extreme wind speeds

In the calibration of statistical models for mean and extreme wind speeds, data coming from historical series measured at meteorological stations are used. In most of the cases, these do not comply with characteristics of the model to be calibrated. In particular, this is due to a finite onset wind speed of anemometers and to the discontinuous sampling. As a result, the mean wind speeds are often underestimated. In addition, when the extreme wind speeds are described through the Gumbel model, these are overestimated due to the non-perfect fitting of the data. In this paper the three issues related to the existence of a measurement threshold of anemometers, of the discontinuous sampling of mean wind speed, and of the appropriateness of the Gumbel distribution for the description of extreme wind speeds are discussed, based on the analysis of the historical records available to the Meteorological Service of the Italian Air Force, using an empirical approach. An estimate of the inaccuracies associated with each of the approximations above, is given.