## 6 Summary and Conclusions  
Wind profiling lidars on a floating platform or floating lidars are susceptible to motion-induced errors. Even though previous studies have investigated floating lidar errors, they have not distinguished between motion-induced errors in lidar measurements and random errors arising from the lidar measurement principle. In this study, we addressed this gap by analyzing the results of the Grimstad experiment, a controlled motion experiment, in which two different types of wind lidars were installed on a moving platform, and two corresponding lidars were located five meters away as fixed reference lidars. We also evaluated our novel motion correction method in reducing the motion-induced errors. Our results showed that the lidars have very good agreement in their mean wind speed measurements when there is no motion. However, the agreement between lidars of the same type drops as the height increases. This difference is more pronounced in the WindCube V1, with the absolute percentage error (APE) ranging from 2% to 7%. Interestingly, the turbulence intensity (TI) estimate does not differ between different types. In the presence of motion, the WindCube V1 is more prone to motion-induced errors compared to the ZephIR 300 in the majority of test cases. Moreover, the correlation between the moving lidar and the reference lidar of each type is consistently higher for the ZephIR 300, indicating that the WindCube V1 is more affected by motion. Additionally, our study provided the following findings:  
* Yaw motion with a frequency close to the sampling frequency of the lidar can cause underestimation of mean wind speed for moving lidars. In our observations, the APE for the WindCube V1 exceeded 14%, while for the ZephIR 300 the APE remained below 6%. The correlation between the moving and reference lidars varied between 0.25 and 0.75, while the ZephIR 300 lidars showed a higher correlation than WindCube V1 at all yaw test cases. * Pitch motion (rotation along the N-S direction) with moderate frequency did not cause a significant discrepancy. Yet, as the motion amplitude increased, APE between the moving and reference lidar for both types increased following with a drop in correlation between lidars. This was the case for TI estimates as well. Our results showed that the motion-induced errors are affected more by pitch motion amplitude than by motion frequency. * Roll motion (rotation along the E-W direction) showed a marginally lower average wind speed for moving lidars compared to the reference lidars at both 85 m and 145 m. Additionally, their TI estimations were higher than reference lidars at both heights. Higher TI was observed in higher frequency test cases. The APE between moving and reference lidars was observed to be less than 5%. The high correlation between lidars persisted even with motion, but a decline in correlation was observed at the greater height (145 m). * Heave motion (vertical motion along the Z-axis) caused the moving lidars to measure mean wind speeds equal to or slightly lower than reference lidars. The WindCube V1 lidars had a higher discrepancy in TI estimations than ZephIR 300. The APE between the moving and reference lidars was less than 5% for both types at 85 m while this value increased for WindCube at 145 m.
* Surge motion (horizontal movement in N-S direction) results showed the moving and reference lidars had similar mean wind speeds and APE less than 2.5% in 85 m and less than 7.5% at 145 m. In these test cases, strong correlation between lidars was observed. TI estimates of moving lidars were higher than those of the reference lidars. Our results showed that while surge motion had negligible effect on the ZephIR 300, the WindCube V1 had susceptibility to motion-induced errors. Ultimately, the WindCube V1 showed larger variations before and after motion compensation compared to the ZephIR 300. However, the applied motion compensation was effective for both lidars, and the motion-induced errors were reduced by 85% and 82% after motion compensation, respectively.