Analysis 02: OWF Effect on the Ocean - On the Effect of Offshore Wind Farms on the Atmosphere and Ocean Dynamics - page 59

Fig. 5.7 Development of 12-turbine OWF effect (OWFr-REFr) with time along S-N cross
section through the OWF at surface (a1-c1) and at 12-m depths (a2-c2) for temperature (a1-
a2), salinity (b1-b2), and density (c1-c2). Time range comprises 30 days of constant operating of
wind turbines. OWF district is marked with dashed-dotted lines
horizontal processes seem to support exchange by time over the model area, which
first affects the surface.
If different time steps are compared at the beginning of the simulation, it is
apparent that the upwelling cell has faster vertical velocities than the downwelling
cell. Due to that, cooling is slightly faster than warming. Therefore, it also takes
longer to warm lower ocean layers.
Figure 5.8 shows temperature profiles for different time steps of the ocean
simulation at two points 6 km south and north to the OWF center along the S-N
cross section. In the case of downwelling, the thermocline drops from 12 to 20-m
depths. In the area of upwelling, the thermocline rises by more than 10. The change
in thermocline depth grows with time; its magnitude depends on location.
Due to the stable distribution at the beginning, the thermocline cannot be fully
eroded, but in the case of a more realistic temperature distribution, the ocean would
be stronger mixed, which is shown in Sect. 5.4 . Compared to the beginning of the
simulation, the temperature at the upper layer undergoes a decrease of an average of
1.5 C within 30 days southerly of OWF and leads to a temperature gradient
between south and north of approximately 2 C.
Details of physical processes linking and triggering the OWF induced phenom-
enon on the ocean system are analyzed in the next sections.