ESDU 88038:2012

ESDU 88038 provides an estimation method for use when
meteorological records are inadequate to provide the data directly,
or when they are not readily corrected for differences between the
terrain at the site and at the measuring station, or when a rapid
estimate of wind speed frequency of occurrence is required. It uses
a theoretical approach, with some empirical factors, to relate the
parameters of the Fisher-Tippett Type 1 extreme value distribution
to the parameters of the parent Weibull cumulative distribution
from which the number of hours when the mean wind speed exceeds
specified thresholds can be calculated. In practice, the extreme
value mode and dispersion parameters (or estimates) are more
readily available for various regions of the world than the parent
distribution data. The method may be used inversely, as illustrated
in ESDU 87037, to estimate extreme wind speeds from relatively
short records of the parent distribution. It applies to winds from
any sector and to the case when all wind directions are combined. A
method is also provided to estimate the proportion of hours in a
year when the wind direction is in a particular 30 degree sector.
Guidance is given on correction factors for changes from the
conditions of the basic data in terrain roughness, height and
simple topography. The method has been tested against data from 50
UK sites and is considered to be applicable to wind climates in
middle to high latitudes. It has been tentatively extended to apply
to a wind climate contributed by more than one mechanism (for
example, frontal depressions and thunderstorms).