the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 18 Aug 2025
Emerging mobile lidar technology to study boundary-layer winds influenced by operating turbines
Abstract. The development of a microjoule-class pulsed Doppler lidar and deployment of this compact system on mobile platforms such as aircraft, ships, or trucks has opened a new opportunity to characterize the dynamics of complex mesoscale wind flows. The PickUp-based Mobile Atmospheric Sounder (PUMAS) truck-based lidar system was recently used during the American Wake Experiment (AWAKEN) to assess the general structure of boundary-layer wind and turbulence around wind turbines in central Oklahoma.
Wind speed profiles averaged over PUMAS transects influenced by the operating turbines (waked flow) show a 1–2 m s-1 reduction compared to mean undisturbed (free flow) wind speed profiles. Spatial variability of wind speed was observed in time-height cross sections at different distances from turbines. The wind speeds were about 9–12 m s-1 at 6 km distance compared to 5–7 m s-1 at the transects near the turbines.
The PUMAS dataset from AWAKEN demonstrated the capability of the mobile Doppler lidar system to document spatial variability of wind flows at different distances from wind turbines and obtain quantitative estimates of wind speed reduction in the waked flow. The high-frequency, simultaneous measurements of the horizontal and vertical winds provide a new approach for characterizing dynamic processes critical for wind farm wake analyses.
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CC1: 'Comment on wes-2025-79', Etienne Cheynet, 19 Aug 2025
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Dear authors,
Thank you very much for this interesting draft! I have just a short question regarding the use of motion-compensated (or corrected) lidar data. Were the data corrected in post-processing, as in the Lollex experiment [1], where Doppler wind lidars were deployed on a vessel moving in an offshore wind farm. Or was the motion corrected in real time using an active system, similar to the gyroscopic self-levelling tables found on cruise ships? Is it possible that both active compensation and post-processing correction were used simultaneously? I believe this information is provided around lines 112–120, but I am not sure I fully understand it.
I am also uncertain which term would be most appropriate:compensated, corrected, or stabilized. Please feel free to propose the terminology you consider most accurate.
Best regards,
Etienne Cheynet
Reference
[1] Malekmohammadi, S., Cheynet, E., & Reuder, J. (2025). Observation of Kelvin–Helmholtz billows in the marine atmospheric boundary layer by a ship-borne Doppler wind lidar. Scientific Reports, 15(1), 5245.
Disclaimer: this community comment is written by an individual and does not necessarily reflect the opinion of their employer.Citation: https://doi.org/10.5194/wes-2025-79-CC1 -
AC1: 'Reply on CC1', Yelena Pichugina, 21 Aug 2025
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Dear Etienne Cheynet,
Thank you for your perfect questions!
There are three components of motion consideration that actually use all three words.
- We use a pitch/roll active stabilization platform to maintain the lidar level in real-time. This enables vertical velocity measurement without needing correction for horizontal wind speed in post-processing step as described in Malekmohammadi et all, 2025.
- We optionally shift our detection window to account for platform motion when the truck is moving at high speeds, [SB1]to keep the measured Doppler velocities within our detection bandwidth.
- Platform and lidar orientation and velocities along all axes are tracked and we are putting them into the “world reference frame” for horizontal wind retrieval. I would consider this to technically be a post-processing step, though we do this in our real-time processing and plotting as well when in the field.
We made serious efforts towards quality control of data during AWAKEN using all our experience of mobile-platform measurements (see Table A1 in Appendix A) with the first implementation of the lidar motion corrected system deployment at a NOAA research vessel in the Gulf of Maine (Pichugina et al. 2012, see the manuscript reference).
In addition, during AWAKEN, we provided 5 min measurements in the stationary position at the beginning and the end of each track, which allows us to check the system performance during the post-processing of data.
Regarding your question about terminology, we refer you to lines 112-119 of the manuscript repeated here for your convenience:
“Two significant obstacles to obtaining accurate wind profiles from the high precision lidar measurements using these techniques are correcting platform motions that get projected into the lidar measurements and maintaining accurate control and tracking of the lidar pointing. To address platform velocity, the platform and lidar orientations and velocities are tracked along all axes so that the measured platform-relative line-of-sight velocities can be transformed into the world reference frame. Motion compensation is also performed at high platform velocities by shifting the output laser frequency to keep the Doppler shifted return signal within the detection bandwidth. To further minimize pointing error and enable a vertically pointing beam, the lidar optics are housed in an active motion stabilization frame that keeps the lidar level in the world reference frame to within 1° at all times.
Sincerely,
Yelena Pichugina
Citation: https://doi.org/10.5194/wes-2025-79-AC1
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AC1: 'Reply on CC1', Yelena Pichugina, 21 Aug 2025
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RC1: 'Comment on wes-2025-79', Anonymous Referee #1, 03 Sep 2025
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Comments on the manuscript entitled "Emerging mobile lidar technology to study boundary-layer winds influenced by operating turbines" submitted to WES
The authors reported a mobile lidar technology (PUMAS) for characterizing wind flows, which has the potential to become a powerful tool for wind assessment in the design and operation of wind energy projects. Measurement results were presented in the paper, demonstrating the capability of the proposed technology. It is an interesting and important work.
The following concerns require proper attention before the manuscript can be accepted for publication.
1. The atmospheric flow evolves as the measurement is taken on a moving truck. There is a characteristic timescale for a specific atmospheric flow event, while the measurement introduced another timescale determined by the speed of the moving truck and the flow event of interest. Choosing a proper path and driving speed seems to be important to ensure the effectiveness of the measurement. What are the authors' thoughts on this issue? What approaches are being taken to cover enough spatiotemporal range in the proposed measurement system? Are there any best practices for measuring typical flow phenomena, e.g., LLJ, wind turbine wakes, and atmospheric flows in complex terrain?
2. Interpretation of PUMAS measurements is not straightforward. The measurements contain distributions of physical quantities in both space and time directions. The authors plot most of their results in the time-height cross sections. I understand that this is partly for comparison with the measurements from the stationary lidar. On the other hand, one advantage of PUMAS is that it provides variations of wind in space (in both vertical and horizontal directions). Can the obtained measurements be employed to show the spatial variation (not in the vertical direction) of a flow phenomenon, say, the downwind variation of wind turbine wakes (the authors showed some results, but the capability does not seem to be well demonstrated)?
3. On lines 657-660, the authors stated the capability of the proposed PUMAS technology in predicting flow statistics of different orders. However, the paper mostly focused on the first-order statistics. It is necessary to examine the proposed PUMAS system in measuring higher-order statistics, like variance, skewness, and energy spectrum.
4. Some discussions are necessary on the uncertainty of the measurements, like how the measurement accuracy depends on the atmospheric conditions, terrains, and the measuring conditions of the PUMAS itself.
5. In the conclusions section, it is suggested to discuss the limitations of the proposed PUMAS technology and potential issues to be addressed.
Citation: https://doi.org/10.5194/wes-2025-79-RC1
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