Interactive comment on “Eddies in motion: visualizing boundary-layer turbulence above an open boreal peatland using UAS thermal videos”

The article uses a thermal imager on a UAS ﬂown at 500 m over boreal peatland to extract surface temperature ﬂuctuation using methodology from Christen et al 2012. Several corrections are applied to the dataset to allow accurate assessment of turbulent statistics. From the temperature ﬂuctuations TIV is performed to extract 2D velocity ﬁelds and a spectral analysis is performed to identity eddy size and shape for eddies of the order of 10-100 m. Further analysis looking at the size and aspect ratio of the eddies is compared to relevant turbulent statistics. I applaud the authors on their methodology and problem-solving skills to treat this dataset to bring it to the

point where turbulence analysis can be performed. I too have dealt with many of the issues described here without any publication to speak of. I see the science within this document as a reflection as step forward for UAS-TIR measurements in atmospheric boundary layer research. While the results and methodology of the document are worthwhile of publication, I have provided a series of major and minor comments below. I find the merit and methodology of the work very high, but the presentation and text to only be fair, thus the comments accumulate to a minor revision. Primarily, I find that the manuscript is lacking a strong review of the literature. I recommend the authors spend more time in the introduction and text to provide citations on turbulent structures. Specifically, the LES community has been studying this topic for some time and should be included. Additionally, the text is very informal, often using inconsistent abbreviations and acronyms. The authors should re-read and work the text to improve its quality and consistency.
Major Comment: Line 53: Be careful, throughout the document you interchangeably use IR and TIR. I understand the overlap, but IR is reserved for short-wave while TIR is reserved for mid-to-long wave infrared radiation. I am only going to comment here on this but will need to change throughout the document.
Major Comment: How did you handle the transmissivity? At such an altitude (500 m) there is likely some degree of error introduced from the transmissivity of the air on the accuracy of the measurement. I believe the FLIR software has a default correction based on the air temperature and humidity, did you use this to correct for the transmissivity?
Major Comment: Many informal sentences. Please use input from co-authors or a reputable grammar editor like Grammarly to help improve make the text more formal. Please rewrite any sentence with the word "so" or beginning with the word "Because." Such phrasing leads to informal sentences.
Minor comment: What is the anticipated error from the noise introduced leaves? Are

Interactive comment
Printer-friendly version Discussion paper there leaves? How does the surface look? A high quality (larger than Figure 4) visual image or satellite view would be very helpful.
Minor comment: Can you add a photo of the flux tower setup?
Minor comment: Please provide more details on how the imregister function (as well as other functions) work. Please remember that Matlab is a paid programing language such that the methodology should be explained as to someone is reprograming this methodology with another language like C++.
Minor Comments: Line 15: comma after (UAS) Line 19: Please change "whilst" to "while" Line 23: The UAS thermal imagery is collocated with a ground-based eddy-covariance system.

Interactive comment
Printer-friendly version Discussion paper periods (>5 minutes) it may not be a concern, but for detection of large eddies this is rather important. Was this method with the aluminum sheet synchronized with a watch? Was there on an onboard GPS available? Was the EC tower GPS synchronized.
Line 93: Remove "easily" Line 98: Please provide a literature source for the emissivity value used.
Line 108 and 109: Remove "The" in phrase "The Steps," also "Steps" is not capitalized   Line 440: These are indeed "large" structures but are not the "largest structures." I would be more specific here and say structures ranging from 1-420 m structures.
Line 443: Again, be careful here about how you talk about turbulent length scales. The smallest scales of turbulence are order 1 mm.

C6
Lines 440-452: While I agree this method is very advantageous and progressive, some of the previous works mentioned were looking at smaller scale turbulence. For the goal of looking at TOS I agree a larger field of view from a UAV is perfect, but the tradeoffs were looking resolution for smaller scale processes and sensitivity from using a thermal imager with a microbolometer.
Line 464: Plethora is informal Line 470: Add citations here about wind speed and TOS. Such papers as "Surface Thermal Heterogeneities and the Atmospheric Boundary Layer: The Relevance of Dispersive Fluxes" by Margairaz et al and "Buoyancy effects on the integral length scales and mean velocity profile in atmospheric surface layer flows" by Salesky et al.
Lines 434-500: I do not feel like this discussion is anything more than a conclusion of the presented work.
Lines 490-495: Several methods exist to exact SHF from thermal imaging products. Morrison et al 2012 as well as other remote sensing papers should be discussed here.