Models, Data, and Methodology - On the Effect of Offshore Wind Farms on the Atmosphere and Ocean Dynamics - page 19

Type of Simulations
The first type of simulation, TOS-01, serves as an idealized approach to analyze
physical aspects in theory, considering different factors with the aim of providing a
common conclusion of the OWF effect on the atmosphere and ocean. The second
simulation type, TOS-02, uses a more realistic approach, with simulations concen-
trating on the OWF effect on the area of the German Bight with the final overall aim
of estimating possible impacts for life in that region.
The concepts of TOS-01 and TOS-02 are opposed to each other, as seen in
Table 3.1 . All simulations for each type of simulations were calculated twice,
considering cases of nonoperating wind turbines (reference run REFr) and cases
of operating wind turbines (OWFr). The difference between OWFr and REFr
(OWFr-REFr) emphasizes the effect of the OWF on respective medium.
In the following, concepts of TOS-01 and TOS-02 are documented.

3.3.1 Model Box Simulations: TOS-01

Simulations of TOS-01 answer the purpose of the analysis of OWF s effect on the

atmosphere and, especially, on the ocean under various external conditions like
wind speed, size of wind farm, duration of OWF operation, depth of ocean, as well
of computational issues regarding resolution and used forcing origin. TOS-01 also
comprises the core of this study—a physical process analysis of the occurring
dynamical changes in the ocean due to the OWF consisting of 12 wind turbines.

'

Model Area in TOS-01 (Model Box)
TOS-01 uses an idealized model area in the form of a box with the size of
240 240 km in the horizontal for both atmosphere and ocean models. The box

is located in the German Bight, with the offshore wind farm alpha ventus in model
center. Figure 3.2 shows the location and dimension of the model area. The offshore
wind farm alpha ventus is located at 006.60 East and 54.00 North. For the ocean
simulation, a model box (ocean box) is used. For METRAS, a similar box is used,
but it is used for atmosphere simulation (atmosphere box). Therefore, the model
area of HAMSOM and METRAS differs only by vertical resolution.

But the position of the model area on the map (Fig. 3.2 ) is important for
HAMSOM because the ocean model uses an isogonic calculation, whereas
METRAS is not isogonic but uses a flat area with grid sizes in kilometer unit.
The isogonic approach allows a more precise application of Rossby radius due to
the isogonic dependence of Coriolis parameter f . That difference between
HAMSOM and METRAS in model design later asks for the interpolation and
projection of METRAS data in the HAMSOM grid.