This short manuscript describes the evolution of upper ocean salinity content in the Mediterranean Sea by using state-of-the-art global and regional reanalyses and objective analyses. As such, it is of interest for the Mediterranean climate community. It is concise, well written, and easy to read. There are, however, a few aspects that need to be improved before the manuscript is suitable for publication. Given that all the points below are relatively easy to address, I recommend a minor revision.

General points

1) Not clear why the reference S_ref is calculated over 1993-2014 and not the full period. By doing this, the salinity anomaly figure / diagnostics (as the mean in Table 2) basically represent the difference between <1993-2021> minus <1993-2014> so the anomaly of the latest 7 years, which is somehow subjective and not necessarily easy to interpret. I would expect S_ref to be the full period, otherwise it needs to be justified with some arguments.

2) Combining different datasets (reanalyses and objective analyses) could be better mentioned in section 2 and 4. There are some intrinsic issues with that, in my opinion. The spread resembles mostly the offset between the products (see also point 4). The trend of the two groups of products are inherently different (Table 1), likely due to the sharp changes in the WMED around 2005-2006. For the latter, it is not easy to understand whether this is only due to a regime shift, or the Argo deployment, or a combination of them. Reanalyses seem qualitatively similar in the shift, but this can also be due to an unconstrained state before 2005. At the same time ARMOR/CORA may be constructed from a climatology that already ingests Argo data, making the comparison complicated. This is beyond the scope of this work, but I recommend the authors to: i) mention how ARMOR/CORA are constructed (how the background is taken?) ii) mention the asymmetry between the two families of products; iii) be less sharp about the causes of the 2005-2006 shift.

3) Being the computation over the 0-300 m layer, I suggest stressing (title, abstract, conclusions) that the analysis refer to the upper ocean salinity content and anomaly, otherwise the study seems to consider the full water column

4) the discussion about the spread in Section 3 should state that the spread on the content (and not that on the anomaly, not shown) is representative of the offset of the dataset, rather than their variations, and thus should be interpreted (see also point 2). This holds for both basin and local scale discussions.

Minor points / typos

L11 with the warming Earth -> in a warming climate

L12 with a large uncertainty -> with large uncertainties

L15 better to state in the abstract which type of products are actually used

L20 salinity content and anomaly EVOLUTION or CHANGE

L28 changes in -> changes of the essential ocean variables

L35 "due to strong mixing" deserves a more sound reasoning here. I suggest dropping it

L59 The mean salinity (S)

L75 "itself" to remove

L93 also ARMOR/CORA are affected, in principle, by the the observational sampling; this sentence suggests only reanalyses are. Better to rephrase the sentence.

Review of the Manuscript SP-2022-11 “The dynamical role of salinity content in the Mediterranean Sea” by Aydogdu et al

General comment to the Authors and the Editor:

The ms presents an analysis, based on gridded datasets of the evolution of upper layer salt content in the eastern and western Mediterranean Sea.

The ms is well organized, clearly written, with a logical structure that guides the reader through the author’s reasoning. However it lacks a bit of a deeper and detailed discussion on what might have induced the temporal changes of water masses.

I suggest to make clear, in the title and throughout the ms, that you are referring to the upper ocean

Some comparison to salinity trends from previous studies would be a valuable addition

If possible, you could consider to provide spatial maps of trends, that can give an interesting perspective on where the changes are more important.

I recommend publication of the ms after minor revision

Some more detailed comments are:

Title: I personally think that the title is wrong, when speaking about content it should be written “salt content” (as we would write heat content, and not temperature content), otherwise I suggest to use (not just in the title but all over the ms) “integrated salinity” (over 0-300 water column).

L10 I suggest to write that the Med it connected to the Black Sea, instead of the Marmara, which is only the connecting basin between Med and BS, beside being better known (wrt Marmara) by non-Med scientists

L11 “The Med will be a hotspot”: actually it is already a hotspot, I think this should be corrected, being a hotspots is a present status, and it implies stronger future changes that will occur.

L11-12: I don’t think the references or acronyms should go into the abstract

L27 delete “expected to be”, it is already a hotspot

L30 and L31 I would replace “water fluxes” with “freshwater fluxes”

L32 it might be worthy to say what is the relative contributions in terms of freshwater of Gibraltar and Dardannels

L32 “which transport the less…”: to be precise it is not the strait that transport the water, they allow the transport of the water…

L 35 and L36 (and everywhere else): it is now recommended to express salinity values without units, so you should remove “psu”

L41 bigger than what?

L46 please explain why you limit the analysis to 0-300 m, and put this clearly in the title and the abstract, since you are reporting only on the upper ocean salt content

L75 why now you are choosing 2014? This is not at all clear, and also might have some implications when you speak about the anomalies….

L76-81 maybe this could go into the Results section

L104-105 I miss some comparison of your salinity trends with those found by previous studies

L114 replace “the salinity from west to east” with “the upper ocean integrated salinity from west to east”

L114-115 you use twice “such as” in the same sentence, I suggest a different wording

L116 should be more correctly “from its low salinity” or “from its salinity minimum”

L130 and L131 delete “modified”, the water mass you are referring to is commonly named just “Atlantic Water”

L137 “more robust outcomes” than what?

Fig1 I suggest to use the same scale otherwise it is a bit confusing (the average basin seems to be higher in some months than the two basins’ averages). Remove psu

Fig. 2 Add the range in the caption “0-300 m”

Fig. 3 I find the colourscale of (b) counterintuitive, I would rather reverse it. In the caption please use the term “integrated salinity in 0-300m"