The frequency distribution of daily maximum wind gusts

The skewness of the frequency distribution of maximum values of meteorological elements and the lack of fit of the normal distribution to the observations is well known. Several types of extreme value distributions are available. However, Gumbel’s (1954) distribution, when plotted on Extreme Value Probability Paper, appears asa straight line and extrapolation is simple. Daily maxima of the homogeneous wind records of Brisbane provide 5, 162 observations. These are first plotted as a frequency distribution and smoothed. They are then plotted on Extreme Value Probability Paper. The reduced variate y is related to the frequency p by the relation y = −1oge (−1oge p). The Gumbel. Distribution plots as a straight line, the equation of which is x = u + (1/a)y, where u is: the mode and 1/a, the slope of the line, is related to the standard deviation of the sample. As the best, fit for the points is a straight line, Gumbel’s distribution fits quite well. The larger the number of observations the more closely does Gumbel’s theory tend to apply.