In this paper entitled «Mesoscale dynamics of an intrathermocline eddy in the Canary Eddy Corridor», Valencia et al. analyse remote sensing data from satellite and high esolution data from a cruise to characterise an intrathermocline eddy in great details. Several aspects of the eddy dynamics and history are considered and discussed.

The topic of the paper is relevant to the comprehension of the mesoscale in the region. The figures illustrates well the findings of the paper. The method is well applied and justified. The text and structure of the paper is of good quality.

I congratulate the authors for their serious and thorough work for this initial submission.

I hence recommend this paper to be accepted in Ocean Science journal after minor, but still important, revisions.

Here are my specific comments:

- l60: Bosse et al. (Scientific Reports, 2019 : https://doi.org/10.1038/s41598-019-49599-8) coud be considered to describe the role of PV as a barrier for horizontal exchanges.

- l68-74 : More boradly speaking subthermocline or intrathermocline eddies have been long known to form via a mechanism of diapycnal mixing (causing the low stratification) identified in two main scenarios : diapycnal mixing followed by restratificationa and gesotrophic adjustment (McWilliams, 1988 : https://doi.org/10.1175/1520-0485(1988)018<1178:VGTBA>2.0.CO;2) and friction in the bottom boundary layer along continental slope (D'Asaro, 1988 : https://doi.org/10.1029/JC093iC06p06685). When a prexisting eddy merges with a surface mesoscale eddy, can lead to the . Similarly, history of winter mixing can lead to the formation of isolated deep core. Since the described eddy is living for one  year, it experiences winter mixing and restratification. Are they any Argo float in the eddy that could be used to describe the vertical structure of the eddy?

- l138 : Please jusrify the scales chosen for filtering (12km seems to be the spacing between stations? what does 8m correspond to?).

- l145 : Could you please justify the choice of NRT product versus DT? (it seems not to be available for the period, but it could be important to mention).

- l204-207 : What does "r" represent in the equation here? and if it is the radial extension in cylindrical coordinate system, how can it provide values of fluxes?

- l215 : Bentaya could be written in italic throughout the manuscript.

- Figure 2 : This figure is very heavy, please consider using transparency and better choice of marker in order to improve its readiness.

- l229, 244 and Fig 3: It might be more instructive to describe omega in terms of Rossby number (ie normalised by f). 

- l287 : This could be the sign of increasing relative importance of high freuency wave compared to mesoscale signal. Do you have means to check this?

- l307 : lens?-like

- l349 : was likely not well resolved.

- Figure 8 : Please find a way to better highlight the section.

- l361 : It looks to me that the radius is actually increasing with depth... Could be maybe hightlight the position of velocity maximum?

- Fig 9: Please add labels for SA. The thicker contours are not visible enough... one label per sigma value is enough. 

- l413 : The location of sign change in vorticity does not usually match with the position of maximum velocity. For instance, a Gaussian eddy with a velocity maximum at R would have a change in sign of vorticity at sqrt(2)R.

- l415 : I understand that the "shell" is defined by the zero vorticity contour, am I right?

- l417 An Eulerian way to look at the ability for the eddy to trap water would be to look at the strain rate (which should be near zero in the eddy center and increase ouside the solid-body core). Did you have a look at this diagnostics?    

- The definition of radius should be clarified. I see at least three definition : location of solid body rotation core, of velocity maximum, and of zero vorticity. It might be usefull to introduce specific notation of each of these for sake of clarity. 

- l430 : The inherent property of PV to be conserved in absence of forcing and dissipation makes it also an important parameter to caracterise the trapping of water.

- Figure 13 : A log scale for PV might show more clearly the two orders of magnitude described in the text.

- Figure 15 : Same remarks as Figure 2.

- l445 : Are they any location of negative PV near the surface? This could be linked to symmetric instability described by Brannigan et al 2017 (see also Thomas et al., 2013 : https://doi.org/10.1016/j.dsr2.2013.02.025).

- l576 : About Biogeochemical impacts : since the Seasoar was carrying an oxygen sensor, how does its distribution look like across the eddy? It could be informative to discuss the possible biogeochemical impact in the light of these measurements.

- l603 : quantities of water

Review of "Mesoscale dynamics of an intrathermocline eddy in the Canary Eddy Corridor" by Luis P. Valencia , Ángel Rodríguez-Santana , Borja Aguiar-González , Javier Arístegui , Xosé A. Álvarez-Salgado , Josep Coca , and Antonio Martínez-Marrero

This manuscript describes the hydrographic and dynamic characteristics of an intrathermocline eddy in the Canary Eddy Corridor (North Atlantic), the associated transports of heat and salt, and energetics. It provides comparison with eddies from other studies, highlighting differences between them. In addition, authors explain in the introduction that their primary objective is to explore the mechanisms responsible for the eddy's formation, but I don't see where they do this. However, the manuscript is complete as it is and worth publication, I don't think additional work is needed. Besides this, I have major concerns about the lack of synopticity of the observations they use. In particular, the observations along the OceT transect were collected over 9 days, and from these non-synoptic observations they provide conclusions on the eddy characteristics that need to be revised. Below I give some ideas to help solve this issue. The manuscript is quite well written, but it would benefit from a revision, in particular the excessive use of short paragraphs is confusing and breaks the fluidity and coherence of the text. Below I provide detailed comments, which I believe should be addressed before the manuscript can be accepted for publication.

•    Introduction clear, well-structured and provides the appropriate context.

•    Check the location of these references: Barceló-Llull et al., 2017a (Vertical velocity) and Barceló-Llull et al., 2017b (Anatomy...). For instance, in L. 36, 191, 436, 491 the reference should be 2017b (Anatomy...) instead of 2017a.

•    L 122: explain what " Continuous yo-yo tows" is.

•    L. 128: give depth of VMADCP sampling.

•    L. 129: "Another phase used in this study, the eIMPACT2 OceT phase (19–28 November 2022), ", rephrase.

•    L. 129: " involved vertical CTD-O profiles" with the SeaSoar or rosette?

•    L. 129: How much time took to complete the 26 stations of the OceT transect? If 9 days (19–28 November 2022), how can you use these data to calculate APE and KE (section 2.3.2) and ASA and AHA (section 2.3.3)? Are you considering these observations collected in 9 days synoptic? Explain and justify.

•    L. 152: " (relative to the average field for the period 1993–2012)" maybe it's clearer to provide the version of the altimetric product that you have used (vDT2021?). 

•    L. 167: " Given the geometry of the Bentayga eddy", explain briefly the geometry you are referring to.

•    Fig. 2 could be cleaner by showing less grey contours (or none) and arrows. Also black contours delimiting dots and stars could be thinner. This is only a suggestion. Fig. 15 could also be cleaner. For instance, it's difficult to see black arrows and lines in chlorophyll maps. In SST the colormap could be changed or the range modified so that the filaments are clearly seen.

•    Figure 2: add a, b, c... labels

•    L. 247-248 " It appears that the onset of these shorter-scale fluctuations coincided with a slight northwestward deflection observed in its trajectory (Fig. 1)." where can we see this deflection? Maybe Fig. 2 1-May?

•    For clarity in the date format and consistency with other figures, in Fig. 1 add year: dd/mm/year

•    L. 256-259: expand these concepts: "reflecting the dominance of geostrophic characteristics even at these scales." " However, the relative energy contributions of these fluctuations did not always align, with greater intensity observed in the variability of the SLA amplitude and radius."

•    L. 639: Lagrangian (with capital letter)

•    Fig. 4 caption: " Vertical dotted lines indicate the positions of oceanographic stations,", dashed?

•    L. 278-283, reference a figure.

•    The conclusions extracted from Figure 4 should consider also the lack of synopticity of the observations. 

•    L. 333: "associated with it"  --> "associated with the eddy"

•    L. 333: "extending from the lower half of the core", specify the depth.

•    L. 335: "The strongest anomalies in σ and Θ were located at its base,", what do you mean by "its base"?

•    L. 334-335: maybe its better to say first that the salinity anomaly signal induced by the eddy had two cores or regions with extreme values instead of one. 

•    L. 339: what do you mean by "higher presence"?

•    L. 340: this is confusing " <-0.25°C and <-0.1 g·kg−1, respectively, "

•    Caption Fig. 8: please rephrase "Each panel displays a unique color scale and density range with 25 contour levels to highlight the isopycnal structure. "

•    L. 345: " even at the shallowest recorded depths (Fig. 8a).", but the shallowest recorded depth is 30 m (L. 127) and Fig. 8a is at 56 m, why?

•    L. 350: Do you refer to Fig. 9 here? This paragraph is confusing.

•    L. 355: at which depths are you referring to?

•    L. 357: " The horizontal section at 120 m depth indicates that lighter water circulating around the inner core extended even at those depths (Fig. 8c)." I find difficult to see this in these horizontal sections.

•    L. 359-360: Which patterns? I don't see here the reason to mention the vertical velocities associated with ITEs. I suggest removing this sentence.

•    Also, authors write many short paragraphs in the manuscript, I recommend that they revise them throughout the manuscript, because sometimes these new paragraphs seem a continuation of what was said before and it is not justified to use a new paragraph.

•    L. 360-361: it would be easier to see the isopycnal deepening in vertical sections. Also, the biconvex shape of the eddy was already described in detail in the previous section 3.2.

•    L. 362: why salinity, and why not also temperature?

•    L. 365: " Within this vertical segment, just below the mixing layer, ", give exact depth layer limits.

•    L. 367: " The highest velocities (>50 cm·s−1) were located at the eddy’s edges, progressively converging towards the boundaries of the inner core with increasing depth. ..." this is confusing, what do you mean by eddy's edges? avoid introducing new terms. Indeed, your definitions of inner core, inner ring, etc. in Fig. 4b are based on observations that cannot be considered synoptic. I see that the complete Seasoar grid was sampled in 5 days, much less time that the OceT transect, and hence the Seasoar sampling could be considered quasi-synoptic*. From Fig. 9a, the velocity associated with the eddy show a similar pattern than in previous ITE studies, and the speed-based radius is coherent in depth. On the other hand, Fig. 4a cannot be considered a snapshot of the velocity of the eddy due to the lack of synopticity of the observations, and the high horizontal resolution can be contaminated by the low temporal resolution. *e.g. Allen, J. T., Smeed, D. A., Nurser, A. J. G., Zhang, J. W., and Rixen, M. (2001). Diagnosis of vertical velocities with the QG omega equation: an examination of the errors due to sampling strategy. Deep Sea Res. 48, 315–346. doi: 10.1016/S0967-0637(00) 00035-2

•    L. 370: " Furthermore, within the inner core, the isopycnals displayed small-scale irregularities, ", where do you see this? what do you mean by irregularities? And how can you see small-scale irregularities after applying optimal interpolation with L =44 km?

•    L. 370: " characterized by doming on one side and deepening on the other side", are you referring to the typical vertical structure of ITEs: doming of the upper isopycnals and deepening of the deeper isopycnals?

•    L. 371: why do you introduce now salinity if you already have density that has the expected vertical structure of ITEs?

•    L. 372-373: remove or justify. What you see is the typical vertical structure of density in ITEs. See e.g. Barceló-Llull et al. 2017, DSR. Indeed, there you can find an explanation of the relation between the vertical structure in density and velocity: " This subsurface intensified anticyclonic flow implies a vertical shear that is consistent with the biconvex isopycnal shape through thermal wind balance. Above (below) this subsurface speed maximum a negative (positive) vertical shear of the horizontal velocity will adjust with a negative (positive) radial gradient of density leading to shoaling (deepening) of the isopycnals. "

•    L. 377: " with a gradual inward movement towards the inner core at greater depths. " remove.

•    L. 379, give values of maximum velocities.

•    L. 380 : " ageostrophic secondary circulation ", ageostrophic horizontal velocity.

•    L. 382: " near the edges of the inner core," remove

•    Section 3.4: OceT transect has non-synoptic observations. Justify the use of these observations instead of the quasi-synoptic Seasoar data for Fig. 10 and the corresponding analysis. I suggest to use the Seasoar observations for this analysis instead of the OceT transect, the radial section of the azimuthal velocity will be easier to interpret, without contamination due to the lack of synopticity, and probably only showing an inner core in solid-body rotation, without the inner/outer rings suggested by authors that may appear due to the lack of synopticity (that by the way, they should explain how they detect them in Fig. 10). Fig. 12 is from Seasoar or OceT data? Add this information in caption, and check that the other captions specify which data is shown in the corresponding figures.

•    L. 432: " extremely low-PV values ", extremely: use a more appropriate word

•    L. 436: " general expectation for ITEs ", expectation: use a more appropriate word

•    Fig. 13a seems too busy, are necessary the white contours? Homogenize all values of PV in text and in the figure to have the same factor x 10^.

•    L. 442: " were associated with isopycnal lifting induced by CEs adjacent to the Bentayga eddy." how do you differentiate between isopycnal lifting induced by the ITE vs. the adjacent CEs?

•    L. 443: " extremely ", change

•    L. 453: which specific stage?

•    L. 455-456: you should mention at least here the lack of synopticity of the observations you used for these computations. Also, the Bentayga radius was different than for the PUMP eddy. What is the climatological first baroclinic Rossby radius of deformation for the region of study (Chelton et al., 1998)?

•    L. 505: "Among these features, ITEs are long-lived mesoscale structures that persist for several months and play a critical role in maintaining the region’s elevated EKE. " ITEs can be long-lived or not. This is not an intrinsic characteristic of them. Rephrase.

•    L. 517: "its", what eddy are you referring to here?

•    L. 517. " The hydrographic properties of its inner core suggest significant trapping of upwelling waters from filaments", how? Explain.

•    Fig. 15 should be improved for clarity.

•    In Fig. 15 I don't see any trapping of waters from filaments. I see high chl and low temperature waters advected by filaments near the eddy, it seems that these waters are moving around the eddy under the influence of the swirling velocities. During eddy formation, eddies trap water within their cores, and this water can be isolated from the surroundings over long distances if the eddy is non-linear (Chelton et al., 2011). In Fig. 15 I see interaction between the eddy and filaments, but I don't see trapping. Indeed, the eddy core characteristics seem quite constant in all snapshots. 

•    L. 522-524 " Interactions between mesoscale eddies, ... Such processes likely contributed to the variability observed in the Bentayga eddy, ", provide evidence of this, or remove. 

•    L. 526-531: This is interesting. Provide exact depths in text (they are different than in Figure B1). Maybe plot more depth layers in Figure B1 if needed. Can you show original data together with interpolated data to check at least visually the interpolation? It seems that in the layers shown in B1 the circulation is anticyclonic, but the eddy seems to be elongated along the north-south direction at 328 m, having an elliptical shape. Do you have an explanation for this? "possibly representing a center with two nuclei" how do you know this? if no evidence, then remove. In text, guide the reader to the exact subplots. In B2, the larger velocities coming from the east are the signal of interaction with another feature that alter the circular shape of the eddy? What remote-sensing observations detect about this?

•    L. 532-537: How is this impacting your integrations? 

•    L. 538-542: What is the relation of this to your results? 

•    In Discussion (and in general) the excessive use of short paragraphs is confusing and breaks the fluidity and coherence of the text. Try to group and link ideas. 

•    L. 544: remove "true", it weakens your analysis.

•    L. 565: " freshwater", water in the ocean is less or more salty, but not fresh.

•    L. 568 " as an ITE, Bentayga is distinct ": some of the eddies you mention in the previous sentence are also subsurface intensified. Rephrase.

•    L. 571-575: " Interactions with upwelling filaments extending from the northwestern African coast (Fig. 15)  likely imbued the Bentayga eddy with heat and salt signatures characteristic of these features ", what do you mean? See my comment before. Expand this paragraph, give evidence or remove. 

•    L. 576-580: Link with your results? Consider moving this paragraph to the introduction or remove. 

•    L. 595: " It is plausible that the six identified AEs ..." provide evidence or remove. 

•    L. 603, 621, etc.: " potentially biogeochemical properties " provide evidence or remove. 

•    L. 11-12: "The intrathermocline nature of the eddy developed during the growth phase, and was shaped by surface convergence enhanced by upwelling filament interactions, followed by isopycnal deepening offshore.", where do you explain and demonstrate this?