Héron et al. analyse a 39-year, 30-member, 1/12° ensemble simulations of the Mediterranean Sea to distinguish intrinsic from forced variability in surface and zonal overturning circulation. Ensemble statistics and temporal scale decomposition reveal that SSH variability is predominantly intrinsic over about 17% of the basin at both timescales, with hotspots in the Algerian, Levantine, and Ionian Seas. Zonal overturning variability is largely atmosphere-driven, though intrinsic processes remain important in intermediate and deep layers near convection sites, particularly in the Levantine basin. Using relative vorticity, the authors further show that Mediterranean gyres span a continuum from strongly forced (e.g., North Ionian Gyre) to largely intrinsic (e.g., Algerian Gyre).

The manuscript is clearly written, with some minor structural aspects that could be refined, and supported by robust results. It addresses a relevant scientific question within the broader context of detection and attribution. Although the study is primarily descriptive, it targets a region where such characterization is still limited and provides insights that can meaningfully advance our understanding of Mediterranean Sea dynamics.

I recommend acceptance with the following minor revisions:

• I would suggest considering a revision of the abstract, as it currently reads a bit convoluted and may not clearly convey the main results of the study.
• L74 -  83: The manuscript provides an extensive description of the ALDERA3 dataset. As I understand, this dataset was not produced by the authors but obtained from another source. I recommend clarifying this point explicitly. In that case, the description could be shortened to include only the essential aspects relevant to the study, with a reference to the original documentation for further details.
• Subsection 2.3.3: Could you add a comment on why you chose 2.5 years as a threshold to distinguish the LF and HF components of the timeseries?
• L124: If I understood your equation correctly, I think it should be H(σ₀(x,y,z,t,n) - σ₀).
• L179 - 185: I would comment differently on the HF SSH variability. The model is in good agreement with the observation and it is indeed underestimating the variability along the Algerian coast and the Levantine basin. However, this is not true in the north-western part of the basin, in the Northern Adriatic Sea, and in the Gulf of Gabes.
• Figure 1: I think that the discussion about the specific gyres would be more easily understandable if the boxes shown in Figure 1 were named or referred to in some way in the Figure itself or in the caption. You could use numbers, letters, or acronyms to refer to each specific box. Moreover, I would recommend changing the color of the axes of the left plots to something other than yellow and that of the boxes in panels e and f to something brighter.
• In subsection 3.2.2, I would add that the bottom zonal transport at low frequency is comparable to the surface and intermediate zonal transports in the regions 17 - 21°E and 27 - 30°E, and comment on that.
• The horizontal lines in panels c and f of Figure 4 are defined later in the text, in section 4.1.3. I would suggest adding that to the Figure’s caption as well.
• L275 - 276: Maybe add a short comment on why large values of forced HF SSH variability are found in the Alboran Sea and in the Tunisian shelf.
• I would unify subsections 4.1.1 and 4.1.2 into a single one since a comparison between HF and LF variability is made, focusing on the similarities and the differences between the two temporal scales. Could you give an interpretation of the reason why the two R_i maps generally agree except for the Tyrrhenian Sea and the Ionian Sea?
• I would suggest doing the same for subsections 4.3.1 and 4.3.2. Could you also further comment on the different results obtained for HF and LF variance of zonal transport, especially about the difference in magnitude between the two?
• I would recommend stressing more the relevance of the analysis of individual gyres and the motivation behind it.
• Have you checked how dependent your results are on the ensemble size? Please comment on that.
• In the conclusion, among the possible deficiencies of the model used, I would emphasize the well-known dependence of internal variability on horizontal resolution. The model has a resolution of 1/12°, which, in the Mediterranean Sea, is often much larger than the Rossby radius of deformation.
• Even though you have highlighted the differences in the conducted analysis compared to the previous studies that you cited (Benincasa et al., 2024, Waldman et al., 2018, and the OCCIPUT project), it would be valuable to include a concise but explicit comparison of your findings with the results reported in those works.

Technical corrections:

• L6: I suggest writing “.. 75% of the interannual to decadal SSH variance of the North Ionian Gyre circulation ..”.
• L12: I suggest rephrasing “and 20-30% at periods reaching 20 years locally” to make it clearer.
• The multiplication symbol in the units of several plotted quantities and throughout the text is not rendered well in the document. I would suggest double-checking the LaTeX expression.
• L76: Missing parentheses for references “Nabat et al., 2020” and “Colin et al., 2010” on the next line.
• L253 - 259: It seems like the same concept, i.e. that the total HF variability of the intermediate westward transport is weaker than that of the eastward surface transport west of 10°E, is repeated two times.
• L270 - 271: I would position the introductory sentence “The left .. at LF (bottom)” in section 4.1 before the beginning of subsection 4.1.1.
• L290: typo in “Figure4d”.
• Figure 5: Specify that you are showing the log of the Power Spectral Density in the caption.
• Figure 6: Increase the size of the title of panel b.
• L339: typo $R_i(t)$.
• L366: typo “behaviors”.
• Regarding the multi-scale character of the Mediterranean Sea, I would suggest adding the following reference: Robinson, A. R., Leslie, W. G., Theocharis, A., and Lascaratos, A.: Mediterranean sea circulation, Ocean currents, 2001, 1689– 1705, https://doi.org/10.1006/rwos.2001.0376, 2001.

The Authors use a 39-year, 30-member ensemble ocean simulation to assess basin-wide contributions of externally forced and intrinsic variability to key components of Mediterranean circulation across different scales.

Overall, the manuscript is well written, presents a relevant scientific topic, and employs appropriate methods. It is therefore suitable for acceptance after a few minor revisions suggested below.

• L33. Can you add one or more references where “chaotic intrinsic variability” (CIV) is first introduced/studied?
• L70. I suggest adding the approximate horizontal resolution in kilometers after „1/12°“.
• L209. Please check the specified locations of the maximums and the corresponding potential densities in Figure 2a. The listed densities and the second location (24° E) do not appear to match the plotted values.
• L213 and L215. Typo „Straits“ to „Strait“.
• L355. I recommend rephrasing as: „Contrary to previous Mediterranean Sea multi-model evaluation studies (e.g., Dunić et al., 2019),...“
• L357-360 and L428-431. Could you elaborate further on the conclusion that the atmosphere is the predominant external driver of decadal fluctuations of the NIG (i.e., BiOS)?
• L434 and L451. Typo „sea“ to „Sea“.
• I suggest adding a short discussion on how horizontal resolution may influence the intrinsic variability.