Vertical extrapolations of wind speed
The extrapolation of wind speeds and wind speed distributions from a lower to an upper level is examined, with particular emphasis on the power law approach. While the power laws are useful for representing the behavior of winds under a variety of conditions, they are shown to be inherently incorrect and misleading for extrapolations. The law's apparent simplicity nevertheless makes it attractive for certain purposes, and its performance at a number of windy sites is tested. The principal feature seems to be the large degree of scatter found from site to site, and even at a single site from one time to the next. Part of this is attributable to the effects of stability, as is seen by dividing the data into daytime and nighttime periods, but the scatter is by no means eliminated by this division. The behavior of the power law exponents is poorer still in complex terrain. While some general tendencies of these exponents can be found, their use cannot be recommended for anything more than a preliminary or rough estimate of wind speeds. Extrapolation formulas for Weibull distributions are also tested with the same data base. They are found to work reasonably well in the mean, but the uncertainties present make their use in any particular case somewhat risky. The use of kites to obtain estimates either of wind speed distributions or power law exponent distributions is simulated. As expected, there is a considerable degree of scatter associated with the results, but the use of kites seems to offer some small possibility of improvement compared to results obtained from the simple extrapolation formulas for Weibull distributions.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 7097248
- Report Number(s):
- PNL-4361; ON: DE83000944
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
WIND
CALCULATION METHODS
DISTRIBUTION FUNCTIONS
DATA COVARIANCES
EXPERIMENTAL DATA
EXTRAPOLATION
MEASURING METHODS
STABILITY
THEORETICAL DATA
VARIATIONS
VELOCITY
DATA
FUNCTIONS
INFORMATION
NUMERICAL DATA
NUMERICAL SOLUTION
170100* - Wind Energy- Resources & Availability (Climatology)