Wind resources at Horns Rev

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of simultaneous measurements (May 1999 to October 2002), data from the offshore site
can be corrected to allow for the fact that the climate during the period of measurement
may differ from the climate from a long-term perspective.
An approximate value for the mean wind speed at Horns Rev can be obtained using a
straightforward comparison of the two periods. The mean long-term wind speed at a
height of 27.5 m at Hvide Sande is 7.14 m/s, but with 6.91 m/s 3.2% lower during the
overlap period. It is therefore to be expected that the mean wind speeds at Horns Rev
are approximately 3.2% higher than the 9.49 m/s measured during the overlap period,
i.e. approx. 9.79 m/s.
In the following sections, the methodologies used in the previous analysis are employed
to update the wind resource estimates for Horns Rev. These results are then compared
with those conducted in previous correlation analyses performed by Tech-wise and
Risoe.
It should be noted that mast shadow corrections have not been used to correct neither
the Horns Rev data nor the long-term data set from Hvide Sande for the following
reasons:
1. To retain comparability with previous analyses.
2. All wind resource estimates are performed based on the wind speeds from the
top anemometer, which is expected to exhibit the least mast shadow effects in
the record.
3. Because it is not possible to correct data from Hvide Sande.
4.2 Resource estimates using different methodologies
Different methodologies are employed to reduce the uncertainties of the predicted wind
speeds. However, the Weibull correction and measure-correlate-predict (MCP) methods
do not account for the differences in directional distribution between predictor and
predictand sites.
4.2.1 Weibull method
The Weibull correction method for extrapolating wind speed data series is based on the
concept of modifying the Weibull parameters to characterise a longer data sampling
period (as described in section 4.1). The method was developed and described in[4], but
in brief is employed as follows:
Report no.: D-160949
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