Research Abstracts 1992-1993: Report No. 93-01

Barbour, P.L. and S. N. Walker, "The Use of Upper Level Wind Records in Wind Energy Studies," OSU Wind Research Cooperative, WRC Report No. 93-01, June 30,1993, 40 pp., $10.00

A major problem encountered in wind resource assessment work revolves around the scarcity of long term reference wind monitoring sites.  Inadequate sting and uncertainties due to changes in both anemometer heights and local vegetation make wind data from many National Weather Service (NES) sites unreliable.  Wind records from twice daily upper-air soundings are not influenced by these factors and may be used effectively in wind energy studies.  Wind data from seven Pacific Northwest (PNW) sites are examined to see if they can be of assistance in performing resource studies, especially those involving long term variations in the winds.

An assessment of the relationship between the winds at the surface and at upper atmospheric levels shows that at many sites in the Pacific Northwest, there is a good correlation between annual wind speeds at the surface and at upper atmospheric levels. Good correlation's were also found between monthly means at most sites however, the magnitude of the correlation coefficients and the number of months with good correlation's varied significantly from site to site. At sites with good correlation's, the upper level winds were used in a climatological adjustment approach to evaluate the influence of large scale synoptic variations on the wind speed at the surface. Results show that, because of long term variations in the synoptic level winds, observed wind speeds at the surface may be between 1% and 7% below what is estimated to be the longer term average. This study also suggests that care must be taken when applying these adjustment techniques to the period before 1976 because synoptic variation appears to have affected both the mean and variability of the winds as well as the relationship between the surface and upper level winds.