This paper describes the use of two different commercially available quadcopter drones for observing temperature inversions during the Arctic winter. Very strong temperature inversions, with temperature gradients of 100-300 K / km were observed immediately above the surface and matched in-situ observations from a 10 m tower and from radiosonde observations. This manuscript provides an excellent description of the technical challenges (related to quadcopter navigation and autopilot use) at high latitudes. The scientific results are limited to flights from a 7 day period in March 2020 although the data collected during these flights illustrate the very strong inversion conditions present at Eureka at the end of the winter. The main issue with the data shown in this manuscript are related to sensor lag, the impact of propellor downwash and sensor location on the quadcopter which result in non-negligible errors in the observed temperature. Despite this the results presented will be of interest to those hoping to use small drones to make meteorological measurements and I recommend that this manuscript be accepted for publication. Below I offer a few minor comments.

Specific comments

In the paragraph starting on line 65 it would be good to discuss some of the smaller fixed wing RPAS used for polar research as these are similar in terms of ease of deployment and payload capacity as multi rotor drones.

Small Unmanned Meteorological Observer (SUMO)

Reuder et al. (2009)

Reuder et al. (2012)

Cassano (2014)

Jonassen et al. (2015)

DataHawk2

Lawrence and Balsley (2013)

de Boer et al. (2018)

Note that Cassano (2014) also note issues with sensor lag for ascent vs descent temperature profiles similar to what you have found.

Line 226: Did you measure the battery temperature during the flight? If not, how do you know the battery temperature during the flights?

A discussion of the temperature measurement issues (sensor lag, downwash impacting observed temperature and temperature differences for the RTD located at different positions on the quadcopter) should be discussed in the conclusions. These are the scientific issues that will limit the usefulness of quadcopters for making scientifically useful measurements of the near surface temperature profile.

While not necessary to cite you may be interested in mid-latitude observations of cold pools using a bicycle based temperature sensor described in Cassano (2014b)

Technical corrections

Line 13: Replace of with above in “60 m of the ground”

Line 49: Replace one with was in “than one measured in Antarctica”

Line 131: Please include link to the relevant DJI web pages here.

Line 316: Replace one with that in “similar to one observed”

References

Cassano, J.J.: Observations of atmospheric boundary layer temperature profiles with a small unmanned aerial vehicle. Antarctic Science, 26, 205-213, doi:10/1017/S0954102013000539, 2014

Cassano, J.J., 2014b: Weather bike: A bicycle-based weather station for observing local temperature variations. Bulletin of the American Meteorological Society. doi:10.1175/BAMS-D-13-00044.1.

de Boer, G. et al. 2018, A bird’s-eye view: Development of an operational ARM unmanned aerial capability for atmospheric research in Arctic Alaska. Bulletin of the American Meteorological Society, doi:10.1175/BAMS-D-17-0156.1.

Jonassen, M.O., Tisler, P.,  Altstädter, B., Scholtz, A., Vihma, T., Lampert, A., König-Langlo, G., and Lüpkes, C.: Application of remotely piloted aircraft systems in observing the atmospheric boundary layer over Antarctic sea ice in winter, Polar Research, 34, 25651, DOI:10.3402/polar.v34.25651, 2015.

Lawrence, D.A. and Balsley, B.B.: High-resolution atmospheric sensing of multiple atmospheric variables using the DataHawk small airborne measurement system. Journal of Atmospheric and Oceanic Technology, 30, 2352-2366, doi:10.1175/JTECH-D-12-00089.1, 2013.

Reuder, J., Brisset, P., Jonassen, M., Müller, M. and Mayer, S., The Small Unmanned Meteorological Observer SUMO: A new tool for atmospheric boundary layer research. Meteorologische Zeitschrift, 18, 2, 141-147, 2009

Reuder, J., Jonassen, M.O., and Olafsson, H.: The Small Unmanned Meteorological Observer SUMO: Recent developments and applications of a micro-UAS for atmospheric boundary layer research. Acta Geophysica, 60, 1454-1473, doi:10.2478/s11600-012-0042-8, 2012.

Revies of the manuscript

"Drone measurements of surface-based winter temperature inversions in the high Arctic at Eureka"

by Tikhomirov et al.

The authors present measurements of temperature profiles obtained with quadrocopters in the high Arctic in winter under challenging environmental conditions. The description of the methodology is sound and of interest to a broad range of scientists.  In particular the technical challenges that were encountered can be very valuable for other drone operators.

There are a few minor comments. My only major point is the suggestion to correct the measured profiles for time lag and take this into account for the analysis of lapse rate, which might be strongly influenced by the correction.

The article is clearly structured and well written.

Detailed comments are attached.

The authors present field deployments testing two types of quad-copters in the harsh conditions of the high-Arctic in winter. The technical description and challenges are relevant and clearly articulated. In general, the work presented here seems very useful for the establishment of high Arctic measurements by drones. Nevertheless, some of the technical issues discovered were only stated but no possible amendments were suggested/applied. Also, the presentation of the results needs some augmentation, especially when comparing to local measurements. More statistical analysis and discussion might be warranted, especially since the current study findings show much deeper inversions than previously suggested for the Arctic (versus the Antarctic).

Minor comments:

Line 17 in the abstract: agrees well with the one (one comparison seems odd)

Line 56, positively correlated with what?

Line 99-100, sentence too long; consider parsing

Line 123, on SBI shaping

Line 144, specification of 0.1 m

Line 168, the results showed good agreement (can you please specify the correlation coefficient? Number of data points?)

Figure 5 and its discussion: the results shown are for one short profile. I would expect seeing some additional statistics and comparisons with the FT and radiosonde data during the campaign duration, to support or decline the proposed biases and/or agreements.

Also, the temperature measurements show lapse rates much higher than previously observed in the Arctic region and this also calls for some additional discussion.

Lines 355-357, the temperature profile differences between the passes in Figure 7 are not always “slight”; there are some variations of 1 degree (subplot c), which warrants more attention. Is there a reference instrument that can attest to the change in ambient conditions over this time?

Figure 9 caption: probably course and not coarse

Line 370, not able to maintain

Figure 10, it is interesting to see the better agreement for the FT flights; is this a coincidence or the result of the location/specific conditions? Were additional comparisons were made with the FT?

Fig.11-12, I think there is room for further discussion of the results, especially on the different profile shapes on the different days and their similarity (dissimilarity) on the different days in the gully vs. the runway. For example, profile shapes in Fig. 12 seem similar but shifted between the gully and runway, while Fig. 11 shows more similar trends. More discussion on the conditions and why we see these results.

Line 413: Field instead of Filed

Lines 413-415, while IR sensor and a Lidar can be a valuable addition, these are much heavier instruments and more complicated installations, so mentioning their addition as a side-note might not be appropriate without further scrutinization. Maybe state the expected challenges from such add-ons.