Articles | Volume 20, issue 2
https://doi.org/10.5194/tc-20-1279-2026
© Author(s) 2026. This work is distributed under the Creative Commons Attribution 4.0 License.
Role of precipitation and extreme precipitation events on the variability of ice core surface mass balances in Dronning Maud Land: insights from RACMO2.3 and statistical downscaling
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- Final revised paper (published on 18 Feb 2026)
- Supplement to the final revised paper
- Preprint (discussion started on 10 Feb 2025)
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Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
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RC1: 'Comment on egusphere-2025-192', Anonymous Referee #1, 13 Mar 2025
- AC2: 'Reply on RC1', Sarah Wauthy, 23 Apr 2025
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RC2: 'Comment on egusphere-2025-192', Aymeric Servettaz, 19 Mar 2025
- AC1: 'Reply on RC2', Sarah Wauthy, 23 Apr 2025
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AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload
ED: Reconsider after major revisions (further review by editor and referees) (28 Apr 2025) by Emily Collier
AR by Sarah Wauthy on behalf of the Authors (29 Aug 2025)
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EF by Mario Ebel (29 Aug 2025)
EF by Mario Ebel (29 Aug 2025)
EF by Mario Ebel (29 Aug 2025)
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ED: Referee Nomination & Report Request started (03 Sep 2025) by Emily Collier
RR by Aymeric Servettaz (15 Sep 2025)
RR by Anonymous Referee #1 (01 Oct 2025)
EF by Mario Ebel (09 Sep 2025)
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ED: Publish subject to minor revisions (review by editor) (01 Oct 2025) by Emily Collier
AR by Sarah Wauthy on behalf of the Authors (08 Oct 2025)
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ED: Publish subject to technical corrections (03 Dec 2025) by Emily Collier
AR by Sarah Wauthy on behalf of the Authors (10 Dec 2025)
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The authors have used the RACMO2.3 model and a downscaled, long-term dataset to investigate temporal and spatial differences in precipitation and extreme precipitation events (EPEs), and their role on Surface Mass Balance (SMB) at three different ice core sites in Dronning Maud Land, Antarctica.
The paper is well structured and flows logically from each section. The introduction and motivation outline the gap in our knowledge and the importance of investigating precipitation and extreme events. The discussion is also comprehensive and provides a different perspective on the results. However, moving some of the discussion points from the discussion to the results or introduction would provide the reader more trust in the results and the use of the model for assessing the precipitation. In addition, the results could be separated into spatial and temporal distribution to better aid the understanding. I do think major revision is required, as some of the results are not clearly explained or presented. I am also unsure about the use of the multiple datasets and how they compare or validate the observations and each other. I believe the study sheds light on an important topic, and showcases the difficulties of using relatively lower-resolution models to investigate SMB at site-specific observations, especially in a geographically complex region. I think the conclusions are valid and important, but the results need more clarification and justification before it can be published.
Comments:
Your introduction is very comprehensive, and your motivation is clearly outlined. No comments for the introduction.
Major revision:
Section 2.3: More information is required for this product. Add the time period to line 140 - 'Extending the time period covered by RACMO' is not enough for the reader to assess the length of time. Even though you later say the ESM was used from 1850-2014, it is not clear if the downscaled final product also uses this same timeframe. Which version of high-resolution RACMO is used? 2km or 5.5km? What resolution is the downscaled dataset? The reader shouldn't have to read Ghilain et al. 2022 for this information, given that it is important to the study. The downscaled product uses RACMO data, but there are large differences in the outcome, especially for the EPEs, but this isn't reflected in results or discussion – you should discuss this.
Which variables are you using? Snowfall or precipitation? Are these synonymous or comparable between the downscaled dataset and RACMO? Does total precipitation = snowfall in this region, or are their times of rainfall in summer?
Section 3: There are major differences between the simulated SMB by RACMO and the ice core records. This is the first thing reported and then makes it very difficult for the reader to trust that RACMO is going to be used for the rest of the study. The justification for using it comes in the discussion, but you should consider moving this earlier, and perhaps bolstering this justification further. Almost 50% of the ice core SMB is not represented in the model – if precipitation is the main component, are you convinced that the model is representing the precipitation properly? Whilst models are always wrong, there is additional model justification and testing which is presented in the discussion which could perhaps come early in the results to bolster the reason for continuing to use RACMO despite the consistent, large underestimation. It would be ideal to see more comparison of the key variables such as precipitation with other observations.
The discussion section regarding complexity of SMB in ice cores should perhaps be moved to the introduction or results. In my case, I am very familiar with RACMO and the SMB analysis in the polar regions, but haven't used ice cores as observations before. Therefore, a straight comparison of the ice core and the model seems like a bad idea, given how poorly RACMO captures the ice core observations. However, I do see value in continuing the study to analyse the RACMO data and assume that it can be a tool for showing SMB differences in time/space.
With the downscaled data, it isn't even capturing the long-term trends found in ice cores (section 3.2.2), which makes it even more challenging to justify using. If it isn't capturing long-term trends, which typically models can capture, how do you know it is capturing any spatial variability?
The authors give a short analysis of the blowing snow contribution – which is significant, but then it is not investigated further or mentioned in relation to the spatial differences in SMB between the three sites. Perhaps more emphasis should be given to this investigation, especially as you conclude that precipitation/extreme precipitation is not responsible for the spatial differences between the sites. If there is a blowing snow modified version of RACMO, could you investigate (briefly) the differences in the model output with and without this modification?
Figure 3: It would be useful to change this to better allow the reader to compare the products and the locations. Figure 3 is busy and it is too hard to compare SMB from RACMO and observations, this could be a separate figure to the other components. In addition, it is hard to compare the locations when there's a lot happening in one figure. Similarly, it would be useful to get one figure where ice cores, RACMO and downscaled data are presented together. Statements like 'in contract with ice core records' (Line 203) are hard to check in the figures, when long-term SMB from ice cores is on figure 2, satellite-era RACMO is on figure 3 and long-term downscaled data is on figure 4.
Section 3.3: More information is needed on how you calculate the thresholds – does each location have its own 95% threshold – e.g each grid cell which represents the ice core location has a value? Or are you using an area average for all locations? Are the thresholds re-calculated for the downscaled data? Later on, you use ERA5 too – are you calculating the thresholds again for ERA5 data, or simply using ERA5 to extra data on specific dates, which have been above the threshold from RACMO?
Section 3.3.2: I think it is a good idea to look at the synoptic situation during these events, but I question the addition of ERA5 data (also because it is not listed in your data section). This is another dataset, which is not compared to RACMO, the downscaled data or ice cores. Whilst synoptic conditions are generally well captured in ERA5 and most models, you are looking at specific dates of these events. How do you know that ERA5 also captures the EPEs which RACMO is seeing? Precipitation is a difficult variable, even in higher resolution reanalysis products. Perhaps it is better to look at the synoptic conditions in RACMO, rather than introduce an additional dataset and therefore additional uncertainties in the conclusions. If you do stick with ERA5 – there should be some discussion of its useability in this region and how it compares to RACMO. In addition, do you select the data from ERA5 based on dates in RACMO, or do you re-calculate the 95% threshold with ERA5 data?
Section 3.4: The geographic and synoptic set up doesn't particularly align with the characteristics of foehn winds. With the Peninsula, a long, high ridge prevents the air from flowing around the obstacle and therefore forces it over 2000m– this is what creates the foehn winds. However, in the case of ice rises, the airflow could flow around the obstacles, given their size, and likely not create the warm and dry leeside conditions. The definition of a foehn wind is also the warm and dry lee slope winds, and not the reduction of precipitation down wind. Instead, you're perhaps referring to orographic precipitation characteristics, such as rain shadow. I wouldn't introduce the foehn effect here, as it doesn't really apply.
Section 3.4.1: Can you find a different name for the EPEs in this section? Up until now, you have defined EPEs as extreme precipitation events with a 95% or 98% threshold for the value of extreme. However, in this section, EPEs now mean 'percentage of cases where the other sites receive more precipitation than their site-specific EPE threshold'. It is then confusing to try and interpret the results – especially the relative wet/dry of the locations. However, this definition does answer a question I had earlier about whether thresholds were site-specific. With the current definition, I am left confused about whether IC is drier or wetter than other sites during EPEs.
Whilst the differences in EPEs and negative anomalies per location from RACMO (table 4) seem significant, the differences between the sites in the downscaled data seems negligible or insignificant. Have you run any statistical tests on these results? The neg.anom for EPEs at IC and EPEs at TIR are very similar, and the two data sets do not agree with each other. The results here focus on the RACMO set, but you don't discuss the lack of consensus among the datasets. This could be because the downscaled data includes a longer time period, but as stated in your earlier results, there is no long-term trend in the data for precipitation, SMB or EPEs, so this perhaps doesn't answer it. I am really not convinced with section 3.4.1 I understand your hypothesis and perhaps the method of trying to look at it, but the results are quite confusing.
Section 4: This first paragraph about ice core complexity should go in the introduction – throughout the results, I am concerned with how RACMO is representing observations, but this section gives me pause about the ice cores as observations. This level of complexity regarding SMB from ice cores should come earlier, especially for readers who are not experts in ice core interpretation.
If 2.2km RACMO was found to be more representative of the ice cores than 5.5km RACMO, why not use the higher resolution one? Or is the 2.2km RACMO the downscaled product you have used?
Minor:
Section 2.1: Can you provide the elevation of the ice rises – this becomes fairly important for your discussion on foehn winds and the loss of moisture across the trajectory.
Line 165 and 168 say the same thing.
Section 3.2.1 – is this really interannual variability section, or is it more spatial variability? Apart from the first line, the rest of this section is about the different locations.
Line 182: What do you mean by opposing signals in ice core records? Is this figure 2? Apart from TIR which has a decreasing trend, they don't seem to have opposing signals. This is hard to tell in figure 3 too.
Table 3: caption says it is contribution to the total annual precipitation, which you also confirm in line 252, however in line 259 you say that EPE variance accounts for 2/3 of the SMB variance. So is the variance SMB and the average contribution annual precipitation? Different variables are used between RACMO (annual precipitation) and downscaled data (snowfall) – are they comparable?
Line 327: I don't understand this sentence – where are the observed global atmospheric pathways observed?
Figure 8: ERA5 data?
Line 356: change 'excludes' to 'rejects'.
Line 438-439: Perhaps include that this is a conclusion from a model, not from observations.