Ooms et al. reconstructed the snow accumulation time series at Dome C over the last 20 years, using chemical composition and physical properties from 35 vertical profiles in a 50 m long snow trench. This is a rare, high-resolution multi-profile trench dataset from the Antarctic Plateau, providing a reference for subsequent SMB research. Their results showed that the annual SMB broadly agrees with stake farm and ERA5, exhibits meter-scale spatial variability, and reflects persistent meter-scale topographic features over multiyear timescales. I believe this work will interest researchers studying surface mass balance (SMB), stratigraphic processes, and ice core interpretation on the Antarctic Plateau. However, the manuscript needs more confirmation and clarification before acceptance.

Major comments:

1. The key result of this study is the establishment of a high-resolution dating method for snowpits. The dating is achieved by aligning the target profile with the sulfate records of old snowpits. The process of manually selecting tie points for alignment is subjective. The article does not quantify the agreement between different operators.

2. I believe that all readers will want to know why this study uses a single profile P0 as the reference to align all other sections in the entire 50-meter trench.

(1) If P0 itself is abnormal, then this anomaly may be passed on to all other profiles, causing a deviation in the dating of the entire. Münch et al. (2016, https://doi.org/10.5194/cp-12-1565-2016) pointed out it is necessary to average multiple ice cores or snowpits to extract climate signals and filter out stratigraphic noise.

(2) When P0 is compared with snowpits that may be hundreds of meters or even farther away, the basic assumption is that the sulfate signal is stable over a considerable spatial scale. However, an important finding of this study is that there is a significant meter-scale spatial variability in snow accumulation. Gautier et al. (2016, https://doi.org/10.5194/cp-12-103-2016) indicates that even ice cores just a few meters apart may have missing records of volcanic events.

(3) The manuscript indicates in the method section that due to too little snow was available to measure chemical elements of the P0 sample, it was mixed with a high-resolution sample from another profile. The authors did not explain the specific method of mixing, and this operation may artificially change the chemical signal of the reference profile.

So I am skeptical about using a single and mixed profile P0 as the reference for the age alignment of the 50 m trench.

3. The authors take the mid-2015 isochrone as an example to validate past topography. Using imperfect individual cases to prove isochrony over a twenty-year period is too weak. I suggest adding more isochrone for verification rather than relying on a single “perfect case”. For example, Sinnl et al. (2022，https://doi.org/10.5194/cp-18-1125-2022 ) emphasize the use of multiple time periods and various indicators to validate age model.

Minor comments:

1. The horizontal decorrelation length of the sulfate signal is 1.26 m in the aligned trench in L204. However, in Figure A6 of the appendix, the legend shows the aligned decorrelation length as “1.40 m”.

2. Only 6 dating points were kept for the age model in L144, but table 1 lists seven different records of snowpits/ice cores.

L24: “offsetted” should be “offset” 

L38/57: unify spelling of “snowpit / snow pit”.

L73: Could you explain the direction of the dominant wind?

L78: remove height .

L81: “was” should be “were”.

Figure 1 caption it is more appropriate to change the + in Figure 1 to follow by.

Figure 1 caption: “1.5cm” should be “1.5 cm”.

L116: Could you tell me why you chose SSA > 40 as the threshold?

L175: Does this indicate that the previous use of 320 as the density value of Dome C is too high?

L487: “alignement” should be “alignment

The manuscript presents work in the area in Antarctica with very low accumulation and mainly no ablation. That gives excellent possibility to study ages of different snow layers. Aim is to define how well annual stratigraphy is visible in older snow and how surface features affect to the stratigraphy over the years. In addition, SMP measurements (snow hardness) correlation with age defined based on chemical composition is studied. Also, annual accumulation rates calculated from the trench, ERA5 and earlier snow stake data are compared. For the analysis, 50m long and 1.5m deep trench was made in December 2019, covering snow accumulation approximately from past 20 years.

General comments

Accumulation hiatus could be explained better.

The main point and impact of the study could be better clarified in the conclusions.

Please write numbers below 10 as text.

Please avoid starting sentences with “Figure …”

I recommend using the CRediT standard for the author contributions. Now it is not clear if any of the authors participated in the field measurements, for example.

Specific comments

Figure 1: P0.3 is not marked to the Fig 1a.

Line 87: Why P0 was not mixed with P0.1 since it is closer than P0.3, right?

Line 63: Change as “Chemical tracers and physical snow properties including snow microstructure (density, specific surface area (SSA) and penetrometry)”.

Line 64:  Change as “methanesulfonic acid (MSA)”

Line 164: Change as “The stakes are measured every year”

Figure 5: Colors are difficult to separate and makes figure difficult to read.

Figure 6b: Figure is very unclear because all lines are top of each other.