Please find the review in the attached PDF.

Reviewer #2

Hailstorm Events in the Central Andes of Peru: Insights from Historical Data and Radar Microphysics

by Jairo Michael Valdivia, David Alejandro Guizado, Elver Villalobos-Puma, José Luis Flores-Rojas, Stephany Magaly Callañaupa, and Yamina Fey Silva-Vidal

General comments:



This study analyzed hail reports as well as disdrometer and upward pointing radar measurements of hail events at one station in the central Andes. The text, including structure, title, and abstract, and the Figures are of good quality. In my opinion, given my specific comments 2-4, the results lack representativeness and are not very impactful. However, some of the results are perhaps worth publishing and given the wealth of different analyses, including recent topics such as polarimetric radar identification, I could see the study having some relevance for the community. Some points should be clarified before publication.

Specific comments:

1. l. 97 a map with elevation and the station location would be very helpful I think
2. l. 97 Hail is typically infrequent on high mountain regions and more frequent in foothills (see Allen 2017 for Rocky mountains in US and Punge 2017 for the European Alps). I'm missing some justification for why this location was investigated. Is hail an often observed threat there (this doesn't seem to be the case from the hail sizes that you observed, <14mm)? If not, I think it should be made even clearer (in intro and summary especially) that the observations are only representative for the high mountain range, not other regions of Peru (probably not even the whole mantaro river valley which you mention in the intro, give its complex terrain).

3. l. 97-103 Are there any other observatories such as this one in Peru which you could add to the analysis? This would increase the robustness of the results.
   
   I'd also personally be very interested in the spatial distribution as our satellite-based detections show some strong activity in Peru, but more in the foothills to the East. Perhaps you can share your experience on this.

4. section 2 in general: Do you have events of Graupel in this region? How did you make sure events were correctly classified as hail? Was there a minimum size? Later you comment on the observed sizes (line 340), which are almost exclusively small, so I'd wager some of the cases were in fact Graupel. Graupel is also not considered in the Disdrometer (probably because it is indistinguishable from small hail for there), which leads me to suspect that many of the "Hailstorms" in section 3.2 are Graupel.
   
   I think this is very important because Graupel can never become large, while hail can. If most of your events are Graupel, then calling this study an analysis of hail events is very misleading. This should at least be made very clear already in the intro and methods, not late in line 340.
5. l. 297 (also l. 385) I'm not a microphysics person but in the reference below, high LDR aloft is attributed to the alignment of ice chips in the electric fields (Melnikov, et al. 2019).

   Perhaps in general, you could compare your results more to those of other studies (I'm sure the one I found is not the only one using polarimetric radar signatures to classify hail)

6. l. 315-319 The radar only sees a vertical section at one point, not the whole 3D cloud, while hail growth happens in 3D trajectories and the stones are advected relative to the updraft (even several km outside the main updraft in some cases), see e.g. Kunjian et al. 2020. Perhaps some perspective on how you relate your 1D (or 2D segments) of measurements to these 3D processes would be insightful. It wasn't clear to me what you mean by "Intuition"

Technical corrections and suggestions:

1. l. 44 add space after "severity"
2. l. 47 I suggest adding Allen et al. 2018 as reference in the brackets
3. l. 52 remove "Beal" once
4. l 60-79 repeating all these points here seems a bit redundant. Consider summarizing them in 2-3 sentences or picking the ones most relevant for your study (such as the microphysical aspects)
5. l 80-81 "In the Andes" is repeated 3 times here
6. l. 101 The text seems broken here, do you mean "...sorrounding the observatory."?
7. l. 106-107 I don't understand this sentence. Weren't the reports localized before 2016 as well?
8. l. 107-110 I recommend starting this sentence with "However, instruments ..."
9. sections 2.1 and 2.2 A lot of this technical information seems irrelevant for the study. I recommend sticking to what is important for hail accuracy and just include a reference for further reading
10. Fig. 3 and elsewhere: I'm assuming the times are in local time not UTC? Be clear (if I haven't overread it)
11. section 3.3: Just a question, do you think the LDR relationship typically observed in horizontal pointing radar (higher LDR for hail) is better or worse here because you use a verticall pointing radar, which sees falling raindrops from the bottom?
12. l.334 "Friedrich" twice
13. paragraph starting at l. 328 Good discussion of weaknesses!
14. l. 405-413 Just my opinion, but his high self-appraisal seems a bit unprofessional. This is an interesting "pioneering study" yes, but I recommend being a bit more humble about the impact in a scientific publication, if it is not ground breaking.

References:

Kumjian, M. R., and K. Lombardo, 2020: A Hail Growth Trajectory Model for Exploring the Environmental Controls on Hail Size: Model Physics and Idealized Tests. J. Atmos. Sci., 77, 2765–2791, https://doi.org/10.1175/JAS-D-20-0016.1

Melnikov, V., D. S. Zrnić, M. E. Weber, A. O. Fierro, and D. R. MacGorman, 2019: Electrified Cloud Areas Observed in the SHV and LDR Radar Modes. J. Atmos. Oceanic Technol., 36, 151–159, https://doi.org/10.1175/JTECH-D-18-0022.1.