An analysis of extreme non-synoptic winds

This paper presents an analysis of wind velocity data relating to I I extreme non-synoptic events obtained from velocity time series pertaining to flow over rural and coastal terrain. For the purposes of the current analysis, an extreme event is deemed to have occurred when the local velocity increases rapidly by 50% or more and decreases within a relatively short time. The data were measured at a number of locations within Northern Europe and in all cases a sufficient array of anemometry was present to obtain an indication of the velocity profile. The velocity profile is shown to alter significantly during such events with three different trends identified. Despite the large variations in wind speed and velocity profile, wavelet analysis is used to illustrate that the underlying turbulent structures exhibit similar behaviour to those expected to occur during extreme wind speed events in boundary layer flow. (C) 2007 Published by Elsevier Ltd.