The German Offshore-Metmasts Amrumbank West and Arkonabecken

The measurements make it possible to
study many important parameters already
in the preliminary phase. To meet the
technological challenges offshore,
measuring platforms are an ideal data
source and an important means for
gathering vital information for subsequent
operation of the windparks already before
beginning to construct them. The
measurements should be extended over
numerous parameters for this purpose.
Some parameters are important, for
example, for constructing the wind power
plants, whereas other parameters are
decisive for designing the foundations.
Knowledge regarding the accessibility of
the platforms can later be applied for
devising appropriate maintenance
concepts. To investigate the windpark
behaviour at an offshore site it is first of all
necessary determine the wind potential
and therewith the energy yield. In the
German waters measuring buoys have
been collecting wave and wind data on the
sea surface since more than a decade.
Such data lack representative
interpretability in the sense that they do
not originate at the elevation of the
machine hubs of future offshore wind
energy plants (90 m). A mere extrapolation
of sea surface buoy data to machine hub
elevation leads to false estimates of the
wind potential and thus to incorrect results
of energy yield calculations. Only
measurements actually made at machine
hub height of the future wind energy plants
are reliable for determining the energy
yield at the respective sites. In the years
2005 ("Amrum Bank West") and 2006
("Arkona Becken Südost"), two measuring
stations were erected in the German North
Sea and Baltic Sea.
2 The Metmasts
2.1 Amrumbank West:
Since April 2005 the metmast
“Amrumbank West” has been constructed
and at work.
Water depth
The water depth is about 24 m. The water
depths around the station vary within
narrow limits.
Fetch distances
Figure 3: Locations and fetches
Figure 3 shows the fetches for the
research station Amrumbank West. They
vary from 35 km in the East to over
500 km in the West. For the main wind
directions the fetch is far more than
100 km.