Improvements to the 'Method of Independent Storms'

This paper presents a critical review of Cook's Method of Independent Storms for analysing maximum hourly mean wind speeds or similar data. An improved method is developed which eliminates the systematic errors in Cook's original method, and which uses an improved set of plotting positions based on the mean values of the order statistics. A standard deviation for each plotting portion is also derived, which enables a fitting procedure using weighted least squares to be adopted. This enables all the highest-order statistics to be used, rather than a limited subset as is the case when the modified Lieblein BLUE(10) method is used. The method is fully automated and a computer implementation is provided. Good results have been obtained for data from 5 UK meteorological sites, but the exploitation of the potential of the new method is at present limited by UK Met Office practice of rounding hourly mean wind data to the nearest knot. (C) 1999 Elsevier Science Ltd. All rights reserved.