# The RUNE Experiment--A Database of Remote-Sensing Observations of Near-Shore Winds
## 5 Conclusions  
The RUNE campaign provides detailed novel measurements of the flow in the coastal zone. The flow during the campaign was mostly westerly, with higher wind speeds than usual in this time of the year and the occurrence of several storms. The availability of four land-based VAD lidars was the highest, generally above 95%. The PPI and dual setups showed a lower availability for longer ranges due to the decrease in backscatter signal. The virtual mast scenario had the lowest availability of the scanning setups because the wind speed is reconstructed 5 km from the coast. The power supply of the lidar buoy was damaged by waves several times and experienced long periods of unavailability. We intercompared the reconstructed 10 min wind speeds from the lidar LOS velocities. The measurements from two collocated VAD lidars show the highest agreement. Those from two VAD lidars that were separated \(\approx\)550 m showed slightly more scatter. The measurements from the dual setup compared well with those from a VAD lidar, despite the largely different sampling rates, measurement volumes, and scanned atmosphere. The 10 min mean wind speeds from the PPI scan showed good agreement compared with those from the dual setup near the coast and the bias was higher for a sampling location further offshore. Higher uncertainty in the wind speed reconstruction of the PPI scans for situations with low LOS velocities is expected and seen for northerly and southerly winds. This preliminary analysis shows us the capabilities of the lidar measuring systems of RUNE. However, RUNE's main scientific questions still remain to be answered and the next steps in our analysis will address them. First, we need to find out what is the accuracy of flow models near the coast. This can be performed by evaluating mesoscale and microscale model outputs (and the  
Figure 11: The mean (marker) \(\pm\) standard deviation (error bars) of the difference between 10 min mean reconstructed wind speeds from the dual and PPI setups at 50 m ASL at three different westward positions. The \(x\)-position is relative to Vara (pos. 2) with positive values going eastward. combination of both) against RUNE measurements that also include the satellite and ocean buoy observations. We propose to construct blind benchmark cases based on RUNE's measurements and distribute the description of the cases among the interested audiences. One of those works within the framework of the New European Wind Atlas (NEWA) project [25], in which the RUNE experiment plays an important role. Within NEWA, a number of modelers are going to evaluate the model results, which will be used to obtain the wind atlas, against high-quality measurements. Second, we need to determine which is the best way to perform near-shore wind measurements in terms of accuracy, and economical and logistical feasibility. The dual setup and the PPI scans are the two options that can cover the area of interest; the dual setup needs two relatively expensive scanning lidars but the accuracy of reconstructed wind speeds is high because we do not need to assume horizontal flow homogeneity within the scanned area. The PPI scans can be performed by one scanning lidar, thus reducing costs and logistics, but we need to assume horizontal flow homogeneity within the scanned area, thus increasing the uncertainty. The question is whether the increase in uncertainty has a large impact when performing wind resource predictions and wind-power estimations. Funding from the ForskEL program to the project 'RUNE' No. 12263 and The European Commission partly funded 'New European Wind Atlas' project through FP7 are acknowledged. We would also like to acknowledge 3E for adding the 3E lidar to RUNE's network, Fraunhofer IWES for the measurements from the lidar buoy, and the technicians of DTU Wind Energy, Fraunhofer IWES and the Danish Hydrological Institute for their work and support during the campaign.