The paper by Metzl et al. presents an impressive data synthesis product, encompassing measurements of dissolved inorganic carbon, total alkalinity, and other hydrographic variables collected from both open ocean and coastal regions, as well as the Mediterranean Sea. These data were assembled within the context of various French research initiatives. Overall, the paper is very well written and the data product will contribute significantly to enrich the global ocean carbon observational database. It should be published in a timely manner after incorporating some changes as laid out below.   

Major comments: 

1. I recommend dividing the paper into two distinct publications. The first should focus solely on detailing the data product, omitting Figures 8 through 14 and their associated discussions. The content suggested for removal would be more fittingly explored in a separate, specialized paper. Alternatively, they can be put into the supplementary.   

2. Please follow the same format as GLODAPv2 as much as you can. Consider making the data available in *.mat and *.nc as well. Folks with routines to import the GLODAPv2 data product should be able to adapt their routines for this new product easily. 

3. Following GLODAP and SOCAT, please consider making this data product available through the Ocean Carbon and Acidification Data System (OCADS) at NOAA/NCEI. Doing so would enrich the product with a community-driven comprehensive metadata template, enhancing its utility and accessibility. Additionally, it would secure the benefit of a long-term archive with version control.

4. Each of the individual cruise data files should also be published in a data assembly center and made publicly available. 

5. In terms of nomenclature, please adhere to community-accepted abbreviations as outlined in Jiang et al. (2022, https://doi.org/10.3389/fmars.2021.705638). For example, use DIC instead of CT, TA instead of AT. 

Minor comments: 

- Throughout the manuscript (ms): data-base --> database

- Throughout the ms, pCO2 or fCO2, the p and f should be italicized. 

- Line 59: PgC is a unit, instead of a substance. Please add "anthropogenic carbon dioxide".

- Line 61, atmospheric CO2 is commonly reported as ppm, which is a molecular ratio, instead of a "concentration". Consider replacing it with "level" or something more appropriate. According to the IUPAC Gold Book, concentration is associated with a per-volume based unit.

- Line 65: Replace Revelle and Suess 1957, with papers that actually report these changes, e.g., DeVries, 2022; Jiang et al., 2023.

- Line 78: has --> have.

- Line 81: add Lauvset et al., 2022

- Line 85: data-base --> database

- Line 85: add these new studies, 

(a) Ma et al., (2023), ttps://doi.org/10.1029/2023GB007765; 

(b) Feely, R. A., Jiang, L.-Q., Wanninkhof, R., Carter, B. R., Alin, S. R., Bednaršek, N., and Cosca, C. E. (2023). Acidification of the global surface ocean: What we have learned from observations. Oceanography, https://doi.org/10.5670/oceanog.2023.222.

- Line 86: add Carter et al., 2021,  https://doi.org/10.1002/lom3.10461.

- Line 90: data-products --> data products

- Line 107: spell out SOCOM

- Line 116: add Ma et al. (2023) and Feely et al. (2023). For more details, see above.

- Line 122: 2013b --> 2023b

- Replace data citations with citations to the paper. That will allow readers to access more information of the product. 

For example:

Jiang, L.Q., Feely, R. A., Wanninkhof, R., et al.: Coastal Ocean Data Analysis Product in North America (CODAP-NA, Version 2021) (NCEI Accession 0219960). [indicate subset used]. NOAA National Centers for Environmental Information. Dataset. https://doi.org/10.25921/531n-c230. Accessed [date]. 2020.

Should be replaced with:

Jiang, L.-Q., Feely, R. A., Wanninkhof, R., Greeley, D., Barbero, L., Alin, S., Carter, B. R., Pierrot, D., Featherstone, C., Hooper, J., Melrose, C., Monacci, N., Sharp, J. D., Shellito, S., Xu, Y.-Y., Kozyr, A., Byrne, R. H., Cai, W.-J., Cross, J., Johnson, G. C., Hales, B., Langdon, C., Mathis, J., Salisbury, J., and Townsend, D. W. (2021). Coastal Ocean Data Analysis Product in North America (CODAP-NA) – an internally consistent data product for discrete inorganic carbon, oxygen, and nutrients on the North American ocean margins. Earth System Science Data, 13(6), 2777–2799. https://doi.org/10.5194/essd-13-2777-2021.

Dear authors,

this is a massive effort that deserves publication, the SNAPO CO2 French service is pivotal to the oceanographic community in France, it merits sustained funding and recognision. It is very remarkable that most of the gathered data is already published both in papers and/or in a public database.

Most of my comments in the annotated pdf relate to organization issues. The text can be organized in a slight different way to highlight for example the quality of the measurements and provide a little bit of more (or less) information in some sections.

So please take the "major revision" as an improvement to highlight the SNAPO good practices.

An issue the authors would consider is the name of the database and its corresponding updates... if the current datebase is name SNAPO-CO2, which would be the next update name? .... so authors may consider SNAPOv1 or SNAPO 1993-2022 or another option.

I also think that the name of the database should not be the same as  the name of the service ... but this is up to the authors and their strategic plan to sustain and highlight the SNAPO performance and reliability.

Best regards