## 3 Results
### Atmospheric Stability in Anholt OWF
The results of the northern part of the wind farm show that the turbulence intensity is weak at longitudes lower than 11 degrees, because the wind has not yet passed through the wind farm, but it can be confirmed that as the hardness exceeds 11 degrees, the intensity of turbulence increases. This was more evident at the lower altitude than the hub altitude. A more rapid increase in turbulence intensity was confirmed in the southern part of the wind farm, which is believed to be because the main wind directions are westerly and southwesterly winds. This is because the wake effect caused by the wind turbine on the windward side overlaps at the same time as the southwesterly wind series wind blows. As such, it can be seen that the intensity of turbulence increases on penetrating the wind farm. Figure 17: Cross-sectional analysis of wind speed and turbulence intensity by latitude at the Anholt offshore wind farm. The distribution of wind speed and turbulence intensity from (50 to 300) m above Mean Sea Level (MSL) can be checked. The black dashed lines indicate the hub height (80 m) and the uppermost part of the rotor disk (140 m) of the wind turbine, respectively. Figure 18 confirms the daily turbulence intensity change by altitude. The intensity of turbulence was highest at 65 m, the lowest point, and peaked at 10 a.m. It showed a general change curve in which the intensity of turbulence decreased at sunset, and increased after sunrise. On the other hand, unlike wind shear-based atmospheric stability classification, atmospheric stability based on turbulence intensity showed a generally stable state. At each altitude, the unstable atmosphere was less than 20%, indicating that more than 60% was a stable atmosphere. Finally, the atmospheric stability is classified according to the Richardson number. The atmospheric stability analysis by wind shear and turbulence intensity described above corresponds to the mechanical atmospheric stability classification method that does not consider thermal factors. However, since the Richardson number uses temperature as a parameter, it is possible to define atmospheric stability according to temperature, and furthermore, heat flux distribution within the atmospheric boundary layer. Atmospheric stability based on the Richardson number was analyzed by dividing the upper part  
Figure 18: (**a**) Daily change in turbulence intensity, and (**b**) atmospheric stability frequency distribution ratio for each height. Turbulence intensity at hub height (85 m) has a peak time at 10 LST, value of 7.84%, and the atmospheric stability is stable. (Sector #1) and lower part (Sector #2) of the rotor disk based on the hub height, and the entire rotor disk (Sector #3). According to the criteria for classification of atmospheric stability according to the Richardson number, the atmospheres in a strongly unstable and unstable state are indicated in red, neutral in green, and stable and strongly stable atmospheres in blue. Figure 19 shows the frequency of appearance of atmospheric stability by sector based on this standard. It can be confirmed that above the rotor, the atmosphere in a stable or neutral state dominates, which does not receive radiation energy directly from the sea level. On the other hand, it was found that in the lower part of the rotor, relatively unstable atmospheric conditions frequently occurred. In the atmospheric stability based on the Richardson number calculated for the entire rotor disk, strong stable or unstable conditions were  
Figure 19: Sectors classified as upper, lower, and whole, based on the hub height for Richardson number analysis in the rotor disk area (**left**). On the right is the ratio of the frequency distribution of atmospheric stability by sector based on the Richardson number. Red indicates unstable (strongly unstable + unstable), green indicates near-neutral, and blue indicates stable atmosphere (stable + strongly stable). From (**a–c**), Sector #1, Sector #2, and Sector #3 are indicated, respectively. dominant.