Wind resources at Horns Rev

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1.4 Data overview
The data coverage rate for the measurement systems is shown in the table below.
Table 1.3 Data coverage rate for the meteorological measurement systems.
Measuring system Data period Hours Data coverage
Primary met. system
Back-up met system
Sonic System
May 1999–Nov. 2002
May 1999–Nov 2002
October 1999–Nov. 2002
1.4.1 Directional sensitivity analysis
30638
30359
26888
99.05%
87.99%
37.35%
The directional sensitivity has been investigated for wind vanes mounted at three
different heights (28, 43 and 60 m above DNN) and is based on more than 21,000 hours
of measurements recorded in the wind speed range (5–25) m/s.
The reference height is 60 m and the bin-averaged differences (bin size =2°) are shown
on Figure 1.7-a. The maximum absolute difference is measured in the northern direction
and decreases towards the south. All three vanes are free of wake effects in the VSV
sector (258 ±90°), although they do not agree very well (+2/-3°) even in this sector. The
best agreement has been obtained for 180° ±35°.
This analysis recommends that the wind direction measured at height 60 m be used, and
not to merge directional measurements from the other levels. The uncertainty of the
absolute directional measurement is ±4°. Figure 1.7-b shows that the mast wake
dominates the measurements in direction 20–45°, corresponding to a boom direction of
212°. The average standard deviation of the wind direction measurement is approx. 4° -
in free, undisturbed winds.
Report no.: D-160949
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