Spatial and temporal correlations of wind speeds

Information on the relationship of wind speeds at different locations is required for a number of applications ranging from the study of pedestrian level wind to early warning systems of high winds for transport. A series of experiments were carried out over a 3-month period at eight sites to determine the wind conditions along a 120 km length of the West Coast Main Line railway in northern England and southern Scotland. Additional data from two synoptic meteorological stations in the area were used for comparison. The wind conditions at these sites are governed by large-scale synoptic depressions. Single and multiple point analysis of the data shows that the wind speeds are well correlated only over time periods of the order of 3 or 4 days – that is, on the time scale of the depressions. For short-term hourly mean measurements, high correlations are obtained only for sites that are less than about 5 km apart. This has implications for the siting of anemometry for warning systems over large areas. A method is presented for the determination of the Weibull parameters for the parent wind speed distribution at a particular site by combining short-term wind measurements and long-term meteorological station data.