General comment

The authors investigate the snow cover at one AWS location at Mt. Ortler (on the glacier) for the 4 year period 2011-2015 using the SNOWPACK model. Main focus of the study is the assessment of wind erosion of snow depending of snow conditions and potential future changes. While the general topic is very interesting and the approach taken understandable, several aspect remain unclear to me. In the following, a list of main and specific comments.

Main comments

Regime shift

In my understanding, the described shift from an erosion- to a melt-dominated regime at Mt Ortler is not a new phenomenon, but is happening since the accumulation areas of the glaciers are decreasing and the glaciers are retreating. This shift seems to now also have arrived at the investigated site fairly high up close to the peak. In case I understand this correctly, why is it important that this regime shift also has arrived at the investigated site?

Ice core, paleo-climatic reconstructions

Reading the manuscript, it seemed that the authors are very closely linked to the ice core community. A lot of parts of the manuscript are designated to the description of ice cores and glacier mass balances in general. Especially the introduction focuses a lot on theses topics. However, in my opinion, this study is not about ice cores or paleo-climate investigations and also not about glacier mass balances. Snow simulation at one point are conducted, which in this case was on a glacier. I think that similar investigations on snow erosion also could have been conducted at a non-glacieted site. The focus of the introduction should be more shifted to snow modelling and the modelling of snow redistribution processes, I think.

New insights, innovative aspect of study

The authors state that already in the 80s and 90s it was reported that temperature regulates the susceptibility of the snowpack to wind erosion. As far as I know, following this type of knowledge snow erosion processes where implemented into SNOWPACK. So the model includes a temperature-dependence of wind erosion of snow. So when your results point out that dry snow erodes more than wet snow, it is because that it is defined like this in the model. Please point out what are the new insight from your study. To me the most interesting aspect is the quantification of the negative temperature feedback on the snow erosion (more melt due to higher temperatures, but less loss due to erosion). This aspect is a bit lost in all the other information, I think. Maybe it is possible to more focus on this aspect?

Precipitation correction, model adjustment

It is not entirely clear to me what correction and adjustment steps with regard to the precipitation were taken. As you take precipitation from a valley station nearby (~1500 m below the site) you first correct for undercatch (according to Kochendorfer?), then adjust lapse-rate based and then multiply everything with a constant factor, right? Please clarify. Please also justify why you selected the constant correction factors for precipitation and wind to calibrate your model. Please also discuss the issue of equifinality. Are there other combination of the two correction parameters that also result in good results? If I understand correctly, you correct the measured wind speed with a factor of 0.7. Why should the at the site measured wind speed constantly have been too high so you have to correct them with this factor? Optimization of a highly complex snow model as SNOWPACK only based on six snow depth measurements between 06/2012 and 09/2014 seems questionable to me. Can it be that you adjust for the wrong reasons and compensate for errors, particularly when only adjusting two constant multiplicative factors. Please consider to snow precipitation and wind measurement before and after correction and if possible also show the full four years simulated including the time steps with observed values using for model optimization. Please also consider to show results of modeled snow layering. Due to your modeling approach you have very detailed insights and the exemplary presentation of an erosion event could be very insightful.

Selection of site

You only have very little data (four years of temperature and wind from one site more than ten years ago). Please justify better why you select this site and data to investigate temperature-dependence of snow erosion. Aren't there better sites and data sets to investigate this aspect? I think that a continuous time series of SD and/or SWE would be very beneficial for the evaluation of the model results. 

Warming/Cooling

The authors choose a very simple a basic approach to assess the impact of temperature changes by simply adding/subtracting 1/2/3 °C to/from the temperature time series. This results in physically in-consistent model input and I am not sure this is a good idea when modelling the show cover with a physically-based snow model. To me the combination of the very simple temperature change approach for only four years of data and the SNOWPACK model needs to be justified better. I am not sure if the robustness of the provided numbers can be guaranteed. I am not sure if the results from 4 years can be generalized considering the complexity of the area. As long-term historical and future climate data is available, I find it difficult to understand why no such data has been used. Please argue why the selection of this simple approach is justified.

Specific comments

Line 5 'unique dataset': As far as I know, a climate station on a glacier is not unique. There are other sites with longer measurements and more measured variables. Why are measurements of snow depth once per year useful to investigate snow erosion? Wouldn't continuous measurements of SD and SWE be required?

Line 33-34: I am not sure I understand why 'elevation' represents a positive feedback mechanisms? How is snow accumulation due to avalanches a negative feedback mechanisms? Maybe the wording 'feedback' is a bit misleading here. High elevations, topographic shadowing and accumulation of snow due to avalanches favor the formation of a glacier, but I would not call it feedback. Maybe it is possible to re-phrase these sentences to avoid misunderstandings.

Fig 1: From what year is the glacier extent? Glaciers seem still fairly large compared to the current state. Please consider to update to a current state. 

Fig 1: The map takes the entire page. Please consider to optimize the figure size, e.g. by including panel b into a.

Fig 2: As it is only 4 years of data, please consider to show the entire time series of the measured data (not monthly values only). Also consider to mark the periods which were gap-filled. Please also clearly show in the figure that precipitation is coming from another location.

Line 188: I am not sure where all the other meteorological variables used to force SNOWPACK at the selected site were coming from. Please clarify where e.g. humidity and the radiation components where measured.

Section 3.1: I think that the description of the AWS site fits better to the data description. Please consider to move.

Line 219: Why not using liquid water content directly to assess if the snow was wet or dry?

Fig 3: I am not sure what to think about the fact that a very low correlation of 0.09 is considers highly significant. Is it possible to plot the values, e.g. for SWE_eroded and T_Ereosion, so the reader gets a better visual impression of the correlation?

Fig. 7 and 8: Figures take a lot of space and it is all white on the right side. Please try to optimize the figure quality.

Line 359: Which snow depth sensors?

Figure 2. I recommend restructuring this figure into three separate panels.

First, a combined plot displaying temperature and relative humidity, using a dual-axis format, provided that relative humidity data are available.

Second, a precipitation plot using stacked bars, incorporating a distinct color scheme to indicate precipitation events occurring when the mean temperature is below 0 °C.

Third, I suggest including a wind rose diagram, divided into 12 directional sectors and approximately four wind-speed bins, to provide a clearer representation of wind patterns.

Line 124. Air temperature and relative humidity are known to be strongly anticorrelated, and analyses based on air temperature are therefore often assumed to implicitly account for humidity effects. However, in the present context relative humidity may exert an independent control on mass balance and snow dynamics, particularly through its influence on sublimation and ablation processes. It is therefore not immediately clear why relative humidity was not included in the analysis. If its influence is negligible compared to that of temperature and wind, this could be explicitly mentioned.

line 195. States: “The snow accumulation was simulated using the Solda precipitation, multiplied by a correction factor to account for the increase of precipitation with elevation (vertical precipitation lapse rate).”. Could you please give some basic information or a reference about this method?

line 200. When you state that “the multiplicative factors for precipitation and wind speed were adjusted iteratively to minimize the RMSE between measured and modelled mass balance at the simulation site”, you are implicitly assuming that these calibration factors do not compensate for other structural deficiencies or errors in the snowpack model itself.

Could you clarify whether this assumption has been evaluated? In other words, how do you ensure that the tuning of precipitation and wind-speed multipliers is not merely correcting for biases arising from other processes (e.g., snow densification, redistribution, sublimation, melt parametrization, or energy-balance components) rather than improving the physical representation of precipitation and wind inputs?

line 207 Maybe this was mentioned or implicitly assumed, but what is the treatment of bidirectional sublimation in the model? Is the contribution of sublimation—both mass loss (sublimation) and mass gain (deposition/subsublimation)—considered negligible compared with other processes, or is there a reason why it cannot be distinguished from wind-driven snow erosion in your results? In other words, how do you ensure that sublimation/deposition is not being misattributed to wind erosion in the mass-balance interpretation? A basic clarification might be needed here.

Line 318. If I understand this figure correctly, this represents the frequency of each threshold wind speed for dry and wet snow. It seems hard to interpret since higher winds are less frequent than lower winds, and there might be a high correlation between high speeds and lower temperatures. It is hard for me to interpret the peak at 9 m/s for dry snow mentioned in Line 312. However, this peak is largely influenced by the higher occurrence of moderate wind speeds in the dataset, rather than indicating an intrinsic preference of the event for this velocity. To better isolate the physical relationship between wind forcing and event occurrence, the event frequency should be normalized by the wind speed distribution. Figure 7 partially solves this issue. A more informative representation is therefore the conditional probability of the event given wind speed, which quantifies the likelihood of the event occurring for a given wind regime and removes the bias introduced by the uneven frequency of wind speeds. Maybe something in this direction should be done or a proper explanation in the text. 

Following this line of reasoning, an additional informative visualization would be a two-dimensional scatter (or binned) plot using wind speed and air temperature as the horizontal and vertical axes, respectively, with the size (or color intensity) of each marker representing the frequency of wind erosion events. This representation allows the combined influence of thermal and dynamical conditions to be assessed simultaneously, highlighting preferential regimes where wind erosion is most likely to occur and revealing potential interactions between temperature and wind forcing that are not evident in one-dimensional distributions.

Line 363. I understand that Table 2 is in some way examining the performance of SNOWPACK during this period. The analysis seems to assume that the model reproduced the snowpack accurately, yet I wonder if a higher frequency validation could be shown to support this assumption apart from Table 2. 

Line 359. This paragraph provides a very clear explanation of the study’s scope and limitations. These ideas might have been helpful at the beginning of the paper. I may be mistaken, and they may already appear in the introduction, but they are particularly clear here.

This may be a minor point, but the figures have a spreadsheet-like appearance that could be distracting to the reader, especially Figure 13.