## 1 Introduction  
The general trend for wind power shows an increase in installed capacity and a larger share offshore [1]. More and larger wind farms are planned offshore in Europe [2] and an increase in the number of wind farms that are built in close proximity in wind farm clusters can be seen [3]. This makes it interesting to study not only the wake interaction inside wind farms but also the long distance wakes behind wind farms and how the wake from one wind farm interacts with other wind farms, in a so-called farm farm interaction. Studies of long distance wakes can be performed with different simulation methods ranging from self similar models, linearized models, Reynolds average Navier Stokes (RANS), Meso scale models (for example using the Weather Research and Forecasting model (WRF)) to Large Eddy Simulations (LES) [4; 5; 6; 7]. WRF normally uses a lower grid resolution than LES, which makes it less computationally demanding but has therefore also the disadvantage that the wind farm needs to be more coarsely parameterized. WRF includes on the other hand more physics about the atmosphere. LES have the advantage that the higher resolution can resolve more scales in the flow and can more accurately model wake interaction especially inside the wind farms [8]. LES have led to good results for studying wakes inside wind farms, see, among others, [9; 10; 11; 12]. LES have been used in fewer studies when it comes to long distance wakes and farm to farm interaction and are still challenging regarding the needed computational resources. Earlier studies of long distance wakes have been performed for Horns Rev I [13] and Lillgrund [14]. In these studies the impact of the Coriolis force was not included and a wind shear with only a velocity in the streamwise direction was used. In a later study of the long distance wake behind Horns Rev I, the wind veer was included [8]. The wind veer was included as a mean value taken from a WRF simulation. When compared with the earlier study the results were closer to site data for the wake behind Horns Rev I. The Coriolis force is in several LES studies using a forced boundary layer (FBL) technique not included in simulations [9; 10]. With the larger distances involved in the study of long distance wakes the turn of the wind due to the Coriolis force becomes of higher importance. As the Coriolis force is proportional to the wind speed, it creates a directional change of the mean wind shear with height. Variations of this force in time and space also occur due to changes in wind speed associated to wind turbine's wakes and atmospheric turbulence. It is natural to question whether the turn of the wake is more greatly impacted by the mean wind veer or change in Coriolis force due to variations in velocity. This question was studied by [PERSON] [15] using RANS with the conclusion that the main impact was from the wind veer due to the downward momentum transport in the wake. For the studied latitude (43.3 deg) in the northern hemisphere it led to a turn to the right of the wake region. [PERSON] also looked at earlier studies of the Coriolis force in the northern hemisphere. The studies had different conclusions as to if the major impact is due to the reduction of the wind speed in the wake that turns the wake to the left or from the increased downward momentum transport due to the wind farm turning the wake to the right due to the wind veer. Some studies focused on the impact of wind veer and concluded that the farm wake turns to the right due to the wind veer. Other studies focused on the impact of the Coriolis force in the wake due to the reduced wind speed. One of the studies was performed with LES using a precursor simulation [16], this study indicated that a turn to the left dominated. These results gave a different conclusion than was found by [PERSON] [15]. Other studies found that the inclusion of the Coriolis force had some impact on the production for a full wake direction due to the turn of the wake [17].