Review of Manuscript # acp-2021-1064 in ACPD: “Evaluating seasonal and regional distribution of snowfall in regional climate model simulations in the Arctic” by Lerber et al.

General comments:

The authors evaluated HIRHAM5 regional climate simulations of snowfall in the Arctic in terms of seasonal and regional distribution. They mainly evaluated surface snowfall rate and radar reflectivity profiles using CloudSat products. Overall, the manuscript is well organized and written, and the logic is clear. The reviewer would recommend minor revision for this manuscript. Specific comments are listed as follows.

Specific comments:

1. The major comment for this manuscript is that the authors could consider some objective metrics in the evaluation, e.g., spatial correlation, Taylor skill score.
2. Lines 105-106: Why was 70N selected as the boundary of two rings? Please justify it.
3. Lines 128-130: I might not agree with this statement. Simulation uncertainty comes from many aspects, and microphysics parameterization is only one of them. Boundary layer parameterization can also significantly influence the model dynamics and then influence the snowfall simulation. If the authors did not conduct the sensitivity test on model physics schemes, it is not suitable to give this statement.
4. Section 2.3: Please provide the quantitive uncertainties of the two CloudSat products.
5. Line 144: “Sect. A” -> “Appendix A”
6. Line 280: “East regions” -> “East region”
7. Line 294: “mmyr⁻¹” -> “mm yr⁻¹”, please correct others throughout the manuscript.
8. Section 4.1: It is better to show the locations of Greenland, Barents, Kara Seas, etc.
9. Lines 400-401: It would be better to show the results in other seasons in appendix or supplement.
10. Section 5.1: Please discuss the differences more quantitatively.
11. Figures 4 and 9: Please conduct significance test of difference for (b).
12. Figure 7: “CFTD” -> “CFTDs”, What’s the meaning of “86500 - 6.6 ˙106” in the caption?
13. Lines 456-457: Please show the locations of the North Atlantic region, the East Siberian Sea and the Beaufort Sea in Figure 9.

Review comments on manuscript “Evaluating seasonal and regional distribution of snowfall in regional climate model simulations in the Arctic”

Authors: von Lerber et al.

General comments:

Using CloudSat observations as the benchmark, the paper evaluates the performance of the HIRHAM5 model in simulating the seasonal and regional distribution of Arctic snowfall. The authors adopted both the observation-to-model and the model-to-observation approaches for the comparison. The study is well constructed. Uncertainties and caveats of the datasets are analyzed in detail. The paper is very well written. The results are very useful to the community and are suitable for publishing in ACP. My evaluation is that the paper has the accept-as-is quality.

Some small suggestions for the authors to consider:

Line 239-240: “Multiple scattering …. not considered in these computations”, does this mean that the model-to-observation process does not include multiple scattering? If so, how does this affect the comparison?

Section 3.2: suggest to add more details on the procedure of using the Jenkinson-Collison method for circulation weather type classification.

Caption of Figure 7: The number at the end didn’t show up correctly in the pdf text.

Figure 9: Panel c was not labeled.