Review of “A climatology of thermodynamic vs. dynamic Arctic wintertime sea ice thickness effects during the CryoSat-2 era” by Anheuser et al.

This paper aims to quantify the components of dynamic and thermodynamic sea ice growth in the Arctic during the winter season from 2010 to 2021. The authors make use of three products: 1) The SLICE model (Stefan’s Law Integrated Conducted Energy) providing thermodynamic ice growth and introduced in an earlier paper (“A climatology of thermodynamic vs. dynamic Arctic wintertime sea ice thickness effects during the CryoSat-2 era”) by the authors of this study. 2) The AWI CS2SMOS sea ice thickness data set providing weekly sea ice thickness grids for the Arctic, and here used to derive total sea ice thickness growth. And 3) NSIDC Pathfinder sea ice motion data to derive advection of sea ice.

The topic is relevant and the approach using the SLICE model is interesting. In general, I think this paper could be interesting and a benefit for the sea ice and climate  community. But from my point of view the study is lacking further information on methods (and may be required corrections), and a sound uncertainty estimation. I have a few major concerns:

1. The SLICE thermodynamic ice growth is subtracted from the total growth in sea ice thickness using the CS2SMOS product. Are the authors aware that the CS2SMOS sea ice thickness for each grid cell does not include open water? So hypothetically assuming that within a grid cell (with pure level ice) sea ice diverges, forming leads, the averaged ice thickness will be the same in CS2SMOS (especially for the CryoSat-2 domain). In other words, thickness=0, is not used for averaging. But I cannot see that this is considered in the current approach.
2. Partly related to 1): I wonder how new ice formation in leads is affecting the overall findings in this study. It is not clear to me how this is handled in this study. SLICE does not seem to consider new ice formation in leads or am I wrong?  
3. The way uncertainties are considered in this study does not seem sound, or at least needs further explanation. I would assume that the uncertainty of the climatological mean as calculated here (Eq. 6) is mostly affected by temporal (interannual and seasonal) variability. This needs some improvement from my point of view. Moreover, the SLICE uncertainty for the weekly thermodynamic ice growth in most of the Central Arctic is close to 0, which does not seem realistic, also considering the comparison with independent data sets in Anheuser et al. (2022).

A comprehensive uncertainty analysis is important here, since different input products are used, where either of them adds to the uncertainty budget. Uncertainty of the sea ice motion product is barely mentioned, but especially in the Fram Strait I believe this can lead to significant errors in the final retrievals, also since ice thickness is very heterogenous there.

Given these points, I suggest major revisions are needed.

Specific comments:

L51 & 55: AEM (airborne electromagnetic) sounding measures the sea ice thickness, not freeboard (can be retrieved only indirectly).

L66: There are some recent studies that already investigated the ice growth components and should be mentioned and cited here: e.g.: Petty et al. (2018), Ricker et al. (2021). The latter also compared observational ice growth retrievals with model outputs.

L73-75: Why is CS2SMOS not mentioned here (and in the entire introduction) as it is used in thus study?

L98: I suggest providing numbers here for the footprint (e.g. 300 m (along track) x 1600 m (across track)).

L155: “so to can” … rewording

L 174: Would it not be correct to use a three-point linear regression over [i-1,i+1], centered at “i”? Otherwise, the gradient is not centered on the target week “i”, but in between “i” and “i+1”.

L193-194: “The most significant negative advection effects, less than 0.04 m wk−1, …”. It is misleading when speaking of negative effects but then stating a "less than" a positive number, which could be again a postitive value.  

L197: Is negative deformation = lead formation?

L465: Please state the version number of CS2SMOS. For most recent data and version history:

https://spaces.awi.de/display/CS2SMOS/CryoSat-SMOS+Merged+Sea+Ice+Thickness

Figures 1&2: The upper and lower limits of the color map seem to be saturated in some areas. I suggest to adjust the limits.

Figure 6: Increase the resolution of the figure.   

References:

Petty, A. A., Holland, M. M., Bailey, D. A., & Kurtz, N. T. (2018). Warm Arctic, increased winter sea ice growth? Geophysical Research Letters, 45, 12,922–12,930. https://doi.org/10.1029/ 2018GL079223

Ricker, R., Kauker, F., Schweiger, A., Hendricks, S., Zhang, J., & Paul, S. (2021). Evidence for an Increasing Role of Ocean Heat in Arctic Winter Sea Ice Growth, Journal of Climate, 34(13), 5215-5227. Retrieved Jan 2, 2023, from https://journals.ametsoc.org/view/journals/clim/34/13/JCLI-D-20-0848.1.xml