The study presents a valuable contribution to our understanding of seasonal snow cover in coastal Greenland and evaluates the accuracy and possibility of using outputs from climate models to reflect snow cover changes in the Arctic tundra. Although ground observations are limited, it is very hard to manually measure snow cover data in the field, especially in the Greenland Arctic because of remote locations and poor logistics. Therefore, I have some minor revisions to improve this manuscript in detail.

Line 53, a spelling error, it should be “however”.

Line 57-59, it seems better to put this content in the section of data.

Line 60, what is the meaning of HS, which appears here for the first time.

Line 136, can you give readers a bit more information regarding the snow simulation module in the RACMO2.3p2 dataset? Which physical processes are considered?

Line 158, what is the method of resampling?

Line 185, why is the window of rolling means 5 days? How about 3 days or 7 days?

The authors present a study showing how in-situ measurements, a reanalysis product and a regional climate model can all be used to estimate snow water equivalent and other snow cover parameters in coastal Greenland. They find that the reanalysis product is more suited to estimating snow cover properties than the regional climate model and suggest that reanalysis data can be used to describe snow cover properties when in situ data are unavailable. This is a solid paper suited for publication in this journal following some minor revisions, which are suggested alongside some broader comments to improve readability below.

General Comments:

The paper would be easier to follow if the same symbols/colours were used to represent each site/dataset across the different figures. To give a few examples, the colour scale goes from blue as the start of the year and yellow as the end of the year in Figure 3, but the reverse is the case for Figure 5; The line styles for the 3 different datasets change between Figure 4 and 8; and different colours and symbols are used to represent the sites in Figures 6 and 7.

The units and notation used to refer to snow water equivalent is not consistent throughout the paper. This is usually referred to in mm w.e., but sometimes w. eq.. I think it would be more in line with other publications to just use mm for SWE. Also on notation, the term “snow cover end” feels somewhat unconventional and does not clarify that that is a date. Consider substituting for something like “snow cover end date” or “snow off date”.

Minor/Technical Comments:

Line 45: Remove “occurring”

Line 53: Typo – however?

Line 101: Recommendations, not recommendation.

Line 106: Please rephrase to clarify if the fractional seasons from 1990 and 2022 have been included in the calculation.

Table 1 (approx. line 117): Why is one of the stations underlined?

Line 123: Is it more likely to be an accuracy of 10% or 15%?

Line 126: What is HARMONIE? Please write out acronyms in full at first use

Line 140: Insert “resolution” after 5.5 km

Lines 144 – 150: Please expand the description of the △snow model

Line 181: Add reference to Fig 2

Table 2 (approx. line 288 onwards): I am not convinced that this needs to be in the main text. I would suggest moving this to the appendix.

Figure 8: There is a lot going on in this figure which makes difficult to get an eye in and the textbox in plot a overlaps with the data presented. I’m not completely sure how best to improve it, but removing gridlines, text box edges and repeated x-axis labels might help.

Line 334: Does density act as a greater control of SWEmax than maximum snowpack height? Could you add something about relative snow depth differences between sites to this paragraph?

Line 363: How long is “relatively short”? Please quantify the length of the timeseries.

Line 371: What is the GEMP? Please define this acronym

Line 421: Other studies suggest that changes in the timing of snow-off will not lead to changes in the length of the growing season (e.g., Kelsey et al. 2021; Semenchuk et al, 2016; Starr et al. 2000). Please justify.

Line 432: Do the limitations need to be a separate subsection when this is only 2 sentences long?

Line 466 : This is a very unusual place to put a summary. If you wish to include this, consider moving it to the beginning of the article.

Line 615: What does the grey dashed line represent in Figure A1?

Line 623: The caption says “all sites” but only 5 of the 9 sites included are shown in Figure A2.

Appendix B: These tables are not referred to in the main text, and I am not convinced that they are needed.

References:

Kelsey, K. C., S. H. Pedersen, A. J. Leffler, J. O. Sexton, M. Feng, and J. M. Welker. 2021. ‘Winter Snow and Spring Temperature Have Differential Effects on Vegetation Phenology and Productivity across Arctic Plant Communities’. Global Change Biology 27 (8): 1572–86. https://doi.org/10.1111/gcb.15505

Semenchuk, Philipp R., Mark A. K. Gillespie, Sabine B. Rumpf, Nanna Baggesen, Bo Elberling, and Elisabeth J. Cooper. 2016. ‘High Arctic Plant Phenology Is Determined by Snowmelt Patterns but Duration of Phenological Periods Is Fixed: An Example of Periodicity’. Environmental Research Letters. https://doi.org/10.1088/1748-9326/11/12/125006.

Starr, Gregory, Steven F. Oberbauer, and Eric. W. Pop. 2000. ‘Effects of Lengthened Growing Season and Soil Warming on the Phenology and Physiology of Polygonum Bistorta’. Global Change Biology 6 (3): 357–69. https://doi.org/10.1046/j.1365-2486.2000.00316.x.