Overview

The authors present results from a hail disdrometer network deployed over three regions in Switzerland. Although piezoelectric sensors have been used before to estimate hail size, this paper improves our understanding of the performance of this particular instrument, as well as its strengths and weaknesses for monitoring hail. The paper is well written and organized. By my reckoning, it also meets the criteria for publication in AMT.

Technical Comments

• Page 2, line 25: Please add the work undertaken by Strong and Lozowski in Alberta.
• Page 2, line 29: This discussion is too simple, even for an overview. Please discuss in more detail the factors that affect the size or dents left by hail on hailpads (e.g., physical properties of the hail, properties of the foam etc.).
• Page 2, line 41: This is more than a “time-recording instrument”, the text needs to reflect more accurately what it does (i.e., it measures the time and number of the impacts, and an estimate of the corresponding hail).
• Page 2, lines 50-51: Do you mean what new information compared to hailpads can be provided? Consider numbering the objectives.
• Page 4, the sensor network. Please provide more information about the spacing of sensor sin the network. What is the mean nearest neighbour distance for each network and all sub networks combined? What is the area of each sub-network and for all three networks combined?
• Page 4, line 81: What are these calibrations spheres manufactured from?
• Page 5, line 89: An air density of 1.2 kg m^-3 seems too high for a study area that includes mountainous terrain. Would it not be more appropriate to use the observed air density for each station location and event? Alternatively, you could use the mean observed air density for a given station location.
• Page 5, line 90: The values for the drag coefficient and bulk hailstone density are reasonable. Please provide references to support these choices.
• Page 6, line 98: I would argue that the effect of the drag coefficient is not limited. What are the authors basing this claim on? Please elucidate.
• Page 8, line 162: A threshold of 35 dBZ is very generous given that hail is typically associated with reflectivities of ~50 dBZ and higher. Is the 35 dBZ threshold value from a previous study? If so, please include the reference.
• Page 8, lines 164-165: Are the number of events excluded sensitive to changing the radius to 2 km or 8 km? How many events were excluded using a radius of 4 km?
• Page 9, event detection: Just a thought. Could one possibly objectively identify events using a temporal KDE method or a clustering technique? This would avoid having to optimize t_mb.
• Page 12, line 209: Please provide the dimensions of the hailpad associated with this surface area.
• Page 18, comparison with hailpad data: I’m perplexed why the authors specifically selected to compare data collected in Switzerland with hailpad data from a network in Italy. It is well established in the literature that there is no unified hail-size distribution, with the results varying by geographical region (e.g., Admirat et al. 1985, J. Climate; Sanchez et al. 2009, Atmos-Res.) and even by storm environment (e.g., Cheng et al. 1985, JACM). The authors do speak to this briefly (lines 282-284), but this choice needs much more rigorous support. Further, there are hailpad data from a network of over 300 hailpads deployed in Switzerland during operation Grossversuch. Why were these data not used for the comparison instead?
• Page 18, equation (4): Can the authors please speak to the similarities and differences between equations (3) and (4). Are they essentially the same, but the form used in (4) was adopted for comparison with the results from Manzato et al. (2022)? The reason for using two equations for the same distribution needs to be made clear.
• Page 21, lines 294-296: It would probably be easier for the reader to follow the discussion if the category names were included following the impact ranges. So, “…: 2 to 5 (scarce), 6 to 25 (intermediate) and > 25 (dense) impacts.”.
• Page 21, lines 311-313: Do the authors have any ideas as to why this might be the case?
• Page 22, hailfall duration: Please also reference the work of Wojtiw (1975, “Hailfall and crop damage in Alberta”). He found a mean hailfall duration of 10.1 minutes.
• Page 22, line 330: Not to be fussy, but I would argue that a storm speed of 6 km/h is “very slow” and not “relatively slow”. A reference providing a mean storm speed would be helpful for adding context.
• Page 24, lines 350 to 356: Is this phenomenon perhaps a reflection of size sorting of hail, for example?
• Page 27, lines 411-412: Is it not possible to suggest a narrower range or a specific value for t_mb? What value will the authors be using in future analyses of these data?
• Page 27, final section: Do the authors plan to locate hailpads or cameras next to some of the sensors in the future? This would be very helpful for evaluating the sensors.
• Page 27, final section: Do the authors have any plans to compare the reports made to the MeteoSwiss hail app with those reported by the hail disdrometers? Is there a particular reason why the crowd-sourced data were not used in this paper?

Typographical Comments

• Page 2, line 38. Suggest saying, “Consequently, there are only a few papers in the scientific literature that discuss local…”
• Page 2, line50: Say, “…how to make the best use of…”.
• Page 4, line 68: Suggest removing “from several events”.
• Page 4, line 81: Suggest replacing “masses” with “spheres”.
• Page 6, line 107: Suggest saying, “…slightly lower signal for the same hail size.”.
• Page 6, line 108: Suggest removing “”…for analysing a single hailstorm…”
• Page 6, line 109: Replace “accuracy” with “precision”.
• Page 21, line 296: Suggest saying, “One reason for doing this is that…”.
• Page 21, line 297-298: Suggest removing sentence starting with “Another”. This text is redundant.