Turbulence Statistics at Douglas Point

Abstract

The standard deviations of azimuth and elevation angle have been determined at Douglas Point, Ontario (at a height of 82 ft), and at Paisley, ten miles distant (at a height of 50 ft), on about 500 occasions during the early summer of 1962. The data have been classified according to wind speed, wind direction and time of day. Individual standard deviations may be affected by intermittency and non-stationarity. However, median values display well-defined trends. Since the trends are similar at two locations with differing terrains, the results may have qualitative applicability to other areas. There is a diurnal cycle with largest median standard deviations during the day. As the wind speed increases, the direction becomes steadier with one exception; at night, the median standard deviations for short pre-smoothing times increase when the wind rises above 10 mph. Because of local obstructions, wind direction has a large effect on the magnitude of the standard deviations. A sample of about 80 concurrent observations shows no close association between standard deviations at Douglas Point and at Paisley.