Analysis 02: OWF Effect on the Ocean - On the Effect of Offshore Wind Farms on the Atmosphere and Ocean Dynamics - page 92

but will impact the magnitude of changes on the ocean variables and, especially, the
depth of the thermocline.

5.3.3 Analyzing OWF Effect on the Ocean Depending
on Wind Park Power

So far, presented effects on the ocean are based on a wind farm of 12 turbines
spanning 4 grid cells, that is, an area of 36 km 2 . Compared to the international
interurban offshore wind farm program, such a wind farm is very small. In future,
one wind farm will embrace a much higher amount of wind turbines starting from
50 up to 160 turbines. This section illustrates the effect on ocean due to different
wind wakes based on various wind farm sizes. Simulations are based on TOS-01
(ocean box) with an induced wind speed of ug 8 m/s. Detailed explanations of

wind forcing are given in Sect. 4.2 . There it is perceived that due to model setup and
model resolution, distinctions between wind wakes are rare and that due to big grid
cells of 3

¼

3 km, the affected areas are similar. Corresponding simulations for
result presentation are T012ug08 TS01HD60F01, T048ug08 TS01HD60F01,
T080ug08 TS01HD60F01, T160ug08 TS01HD60F01. Simulations are based on
forcing sets, including OWF of 12 turbines (T012), 48 turbines (T048), 80 turbines
(T080), and 160 turbines (T160). Affected grid cells are 4 for 12T and 48T, 16 for
80T, and 32 for 160T. Results here are again focused on 1 day of simulation
time step.
Figure 5.27 summarizes the four different wakes in velocity component u based
on different OWFs, which were identified as a fingerprint of the wind field.
Comparing the effect on the u -component at the surface, the runs with different
numbers of wind turbines leads to a similar structure of the OWF induced change,
which mostly depends on the OWF area. In a run with 80 wind turbines, a stronger
exhaustive change between OWFr and REFr occurs, especially a northerly
increased wake flank (Fig. 5.27 c1), due to stronger wake flanks in the wind forcing.
The affected area of runs T012 and T048 is identical due to the same number of
grid cells comprising wind turbines, but the velocity wake in the u -component is a
little more intense by T048 with a minimum at the surface of 0.139 m/s, compared

to 0.136 m/s for T012. A reason for the difference rests in a different magnitude of

the wind field due to the considered power and amount of wind turbines in
METRAS wind turbine parameterization. In the case of T080 and T160, the wake
is deformed by the OWF area, and therefore the wake width in y -direction is bigger
for T080 and T160, compared to T012 and T048. As in case of the wind field, the
ocean s u -wake grows with the number of wind turbines, which means with the

OWF area. Depending on the affected area by the wind wake, the u -component and
already the velocity field implicate a disturbance that is more addicted to the wind
wake district. In all four cases, the minimal u -velocities occur within the OWF or, in
case of a wider OWF, more northerly. Wake flanks are more intense in case of a

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