Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Reviewer of Manuscript remotesensing-3735814: Mooring Observations of Typhoon Trami (2024)-Induced Upper-Ocean Variability: Diapycnal Mixing and Internal Waves Energy Characteristics

This manuscript investigates upper-ocean thermal and dynamical variability during Typhoon Trami (2024) in the northern South China Sea, by utilizing high-resolution mooring observations and satellite datasets. The topic is highly relevant and aligns well with the journal’s scope.  The results are robust and effectively support the main conclusions. The study provides valuable insights into oceanic responses to typhoons, particularly regarding diapycnal mixing mechanisms and energy redistribution between near-inertial waves and diurnal tides during the typhoon. In terms of the overall context, the manuscript is well-organized and clearly written, making it easy to follow.  I have some minor comments that need to be addressed.

Comments:

1. The discussion section does not mention the limitations of mooring observations (e.g., only single-point data cannot capture horizontal characteristics) or the resolution limitations of high-frequency internal wave energy estimates. It is recommended to add a description of the limitations of the study to improve scientific rigor.

2. Lines 562-563: “aligning with the previous observation results on energy transfer from low to high frequencies internal waves.”

Could you analyse the distinctions or relationships between the energy transfer results of earlier studies, instead of merely providing a list of references?

3. Lines 565-568: The last paragraph in the Discussion was only for mesoscale eddies or background flow, which need further revisions and improvements.

4. Some grammatical errors and language issues below need to be addressed.

Line 105: There is a missing space between “(c)” and “Time”.

Lines 139-141: The following analysis does not involve rainfall; please delete the information about the rainfall dataset.

Lines 146-147: Please use the same expression format for three variables.

Line 150: “𝜌₀ is the water density, 𝜌₀ is the reference water density of 1023 kg/m³.” Please correct the error in this sentence. 𝜌 should be the water density at depth z.

Line 152: Remove the word “vertical” in “Vertical velocity shear”.

Line 177: Missing punctuation after formula 5.

Line 212: Replace “SST measurements” with a more precise expression.

Line 216: What does the second grey shadow in the temperature evolution curve of the buoy in Figure 2 represent? If unrelated to the study’s focus, simplify the figure.

Line 258: The date expressions in many places, such as “October 27” and Line 268 “November 4^th”, are inconsistent. Please use the same expression throughout the manuscript.

Line 309: “Figure 6a, c” should be revised to “Figures 6a and 6c”.

Lines 400-402: The correlation coefficient only appears in Lines 387-389 and is not labelled on panel b as in the figure title. Please modify it.

Lines 480-481: “As internal waves propagate, they are significantly affected by the local stratification, leading to continuous adjustments in their amplitude and energy.” This sentence needs additional references.

Line 553: Correct the indentation inconsistency in Line 553 to match the surrounding text.

Line 562: Remove the extra period.

 

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 1 Comments

We deeply appreciate the detailed and valuable comments provided by the reviewer on our manuscript. These insights are invaluable—they not only offer critical guidance for revising and enhancing the quality of the paper but also provide meaningful direction for our research. Over the past five days, we have reviewed relevant literature and revised and restructured the manuscript to address the feedback and improve its rigor. 

Below, we summarize the revisions made in response to the comments on the previous version of the manuscript. We sincerely thank the editors and reviewers for their diligent efforts and time dedicated to reviewing our work, and we hope the revised version meets with their approval.

Reviewer 1: This manuscript investigates upper-ocean thermal and dynamical variability during Typhoon Trami (2024) in the northern South China Sea, by utilizing high-resolution mooring observations and satellite datasets. The topic is highly relevant and aligns well with the journal’s scope.  The results are robust and effectively support the main conclusions. The study provides valuable insights into oceanic responses to typhoons, particularly regarding diapycnal mixing mechanisms and energy redistribution between near-inertial waves and diurnal tides during the typhoon. In terms of the overall context, the manuscript is well-organized and clearly written, making it easy to follow.  I have some minor comments that need to be addressed.

Response: We sincerely appreciate the Reviewer for dedicating valuable time and effort to conduct a meticulous review of our manuscript. Your recognition of the relevance of our research topic to the journal’s scope, the robustness of the results, the clarity of the organization, and the significance of the insights provided is profoundly encouraging to us. Your insightful and professional comments, even the minor ones, reflect a deep understanding of the field and a rigorous academic attitude. These feedbacks are not only affirmations of our work but also important guidance for further improving the quality of the manuscript. We will carefully address each of your suggestions with utmost seriousness to refine the details and enhance the overall rigor of the study. 

Comments and responses:

1. Reviewer 1: The discussion section does not mention the limitations of mooring observations (e.g., only single-point data cannot capture horizontal characteristics) or the resolution limitations of high-frequency internal wave energy estimates. It is recommended to add a description of the limitations of the study to improve scientific rigor.

Response: Thank you for your professional and meticulous comments. Following your suggestion, we have supplemented the description of the study’s limitations in the discussion section. The revised content reads: “However, due to a limited sample of observations, the temperature and current data collected are incomplete, especially in terms of horizontal dimension. Therefore, additional research that includes more comprehensive in-situ observations and numerical ocean models is necessary to enhance understanding in this area.” (Lines 571-575) We hope this revision improves the scientific rigor of the study. 

2. Reviewer 1: previous Lines 562-563: “aligning with the previous observation results on energy transfer from low to high frequencies internal waves.”

Could you analyse the distinctions or relationships between the energy transfer results of earlier studies, instead of merely providing a list of references?

Response: Thank you for your careful reading and valuable suggestions regarding the analysis of previous studies. We have revised the relevant content to analyze the relationships between our results and those of earlier studies, rather than merely listing references. The revised text is: “The analysis reveals a notable rate of energy transfer from NIWs to D1 ITs within the 120–170 m depth range, peaking at 2 × 10⁻⁷ W kg⁻¹. This is consistent with previous observations of energy transfer from low- to high-frequency internal waves. For example, mooring-based observations during Typhoon Fitow (2013) showed that M1 subharmonics and NIWs facilitated energy transfer to high-frequency internal waves (HFIWs) at a rate of 2 × 10⁻⁶ W kg⁻¹ [44]. Similar magnitudes of energy transfer have been documented: 2 × 10⁻⁷ W kg⁻¹ at the shelf break in the East China Sea [43], while open-ocean measurements indicate weaker transfer rates (3.7 × 10⁻⁹ W kg⁻¹) [77].” (Lines 563-570) This revision aims to strengthen the scientific rigor by contextualizing our findings within existing literature. 

References:

[43]. Yang, W.; Wei, H.; Zhao, L. Energy Transfer From PSI‐Generated M1 Subharmonic Waves to High‐Frequency Internal Waves. Geophysical Research Letters 2022, 49, e2021GL095618, doi:10.1029/2021GL095618.

[44]. Yang, W.; Wei, H.; Zhao, L. Near- and Superinertial Internal Wave Responses and the Associated Energy Transfer after the Passage of Tropical Cyclone Fitow at a Midlatitude Shelf Slope. Journal of Physical Oceanography 2024, 54, 1823–1838, doi:10.1175/JPO-D-23-0145.1.

[77]. Chen, Z.; Yu, F.; Chen, Z.; Wang, J.; Nan, F.; Ren, Q.; Hu, Y.; Cao, A.; Zheng, T. Downward Propagation and Trapping of Near-Inertial Waves by a Westward-Moving Anticyclonic Eddy in the Subtropical Northwestern Pacific Ocean. Journal of Physical Oceanography 2023, 53, 2105–2120, doi:10.1175/JPO-D-22-0226.1.

3. Reviewer 1: previous Lines 565-568: The last paragraph in the Discussion was only for mesoscale eddies or background flow, which need further revisions and improvements.

Response: Thank you for your constructive suggestion. We have revised and expanded the last paragraph of the discussion section as follows: “This study presents a detailed mooring-based analysis in the northern SCS. However, due to a limited sample of observations, the temperature and current data collected are incomplete, especially in terms of the horizontal dimension. Therefore, additional research that includes more comprehensive in-situ observations and numerical ocean models is necessary to enhance understanding in this area. Furthermore, this research does not investigate the interactions between mesoscale eddies and typhoons in the SCS, nor does it examine their combined effects with internal tides. The conclusion emphasizes that dynamic processes at multiple scales within the ocean could potentially modify oceanic responses, which may, in turn, affect the development of future typhoons.” (Lines 571-579) We believe this revision addresses your concern by providing a more comprehensive discussion.

Minor comments and responses:

1. Reviewer 1 (previous Line 105): There is a missing space between “(c)” and “Time”.

Response: Thank you for your careful observation. The missing space between “(c)” and “Time” has been added. The revised content now reads: “(c) Time”.

2. Reviewer 1 (previous Lines 139-141): The following analysis does not involve rainfall; please delete the information about the rainfall dataset.

Response: Thank you for your valuable suggestion. As recommended, the information about the rainfall dataset has been deleted, since the subsequent analysis does not involve rainfall.

3. Reviewer 1 (previous Lines 146-147): Please use the same expression format for three variables.

Response: Thank you for pointing out this issue. The revised text now reads: “the square of the buoyancy frequency ( ), shear squared ( ), the Richardson number (Ri), and near-inertial horizontal kinetic energy (NIKE)”. (Lines 147-148)

4. Reviewer 1 (previous Line 150): “ is the water density, is the reference water density of 1023 kg/m³.” Please correct the error in this sentence.  should be the water density at depth z. 

Response: Thank you for your correction. It now reads: “is the water density, is the reference water density of 1023 kg/m³.” (Lines 152-153)

5. Reviewer 1 (previous Line 152): Remove the word “vertical” in “Vertical velocity shear”.

Response: Thank you for your attention to detail. The word “vertical” in “Vertical velocity shear” has been removed, and the revised term is “velocity shear”.

6. Reviewer 1 (previous Line 177): Missing punctuation after formula 5.

Response: Thank you for noting this. Punctuation (a period) has been added after Formula 5 to complete the sentence.

7. Reviewer 1 (previous Line 212): Replace “SST measurements” with a more precise expression.

Response: Thank you for your meticulous and professional feedback. “SST measurements” has been revised to “SST observations”, which is more commonly used and aligns with academic terminology conventions.

8. Reviewer 1 (previous Line 216): What does the second grey shadow in the temperature evolution curve of the buoy in Figure 2 represent? If unrelated to the study’s focus, simplify the figure.

Response: Thank you for your question. The second grey shadow in the temperature evolution curve of the buoy in Figure 2 has been removed to streamline the figure and maintain focus on the study’s key objectives.

9. Reviewer 1 (previous Line 258): The date expressions in many places, such as “October 27” and Line 268 “November 4th”, are inconsistent. Please use the same expression throughout the manuscript.

Response: Thank you for your careful review. Date expressions across the manuscript have been standardized. For example, “November 4th” has been revised to “Nov. 4”.

10. Reviewer 1 (previous Line 309): “Figure 6a, c” should be revised to “Figures 6a and 6c”.

Response: Thank you for your correction. “Figure 6a, c” has been revised to “Figures 6a and 6c” for grammatical accuracy.

11. Reviewer 1 (previous Lines 400-402): The correlation coefficient only appears in Lines 387-389 and is not labelled on panel b as in the figure title. Please modify it.

Response: Thank you for your observation. The correlation coefficient, previously only mentioned in previous Lines 387-389, has been explicitly labeled on panel b of the figure, consistent with the figure title.

12. Reviewer 1 (previous Lines 480-481): “As internal waves propagate, they are significantly affected by the local stratification, leading to continuous adjustments in their amplitude and energy.” This sentence needs additional references.

Response: Thank you for your valuable suggestion. To address the need for additional references, we have revised the relevant content and incorporated the following citations to support the statement: “Typhoons profoundly impact upper ocean temperature and stratification via upwelling and shear instability-driven mixing [75]. These processes disrupt the upper ocean’s stratification: seawater buoyancy frequency dropped in the top 60 m but rose around 80 m (Figure 12a). Such wind-induced stratification changes reshape near-inertial and internal tidal energy vertical distributions, causing refraction and energy adjustments [76]. Since internal waves are highly sensitive to local stratification, their amplitude and energy continuously adapt during propagation [73,74].” (Lines 479-485) These references [73,74,75,76] collectively reinforce the link between internal wave propagation, local stratification, and adjustments in amplitude and energy, enhancing the robustness of the discussion.

References:

[73]. Guan, S.; Zhao, W.; Huthnance, J.; Tian, J.; Wang, J. Observed Upper Ocean Response to Typhoon Megi (2010) in the Northern South China Sea. J. Geophys. Res. Oceans 2014, 119, 3134–3157, doi:10.1002/2013JC009661.

[74]. Leaman, K.D.; Sanford, T.B. Vertical Energy Propagation of Inertial Waves: A Vector Spectral Analysis of Velocity Profiles. Journal of Geophysical Research (1896-1977) 1975, 80, 1975–1978, doi:10.1029/JC080i015p01975.

[75]. Hall, P.; Davies, A.M. Internal Tide Modelling and the Influence of Wind Effects. Continental Shelf Research 2007, 27, 1357–1377, doi:10.1016/j.csr.2006.09.008.

[76]. Xu, Z.; Yin, B.; Hou, Y.; Xu, Y. Variability of Internal Tides and Near‐inertial Waves on the Continental Slope of the Northwestern South China Sea. Journal of Geophysical Research: Oceans 2013, 118, 197–211, doi:10.1029/2012JC008212, 2013.

13. Reviewer 1 (previous Line 553): Correct the indentation inconsistency in previous Line 553 to match the surrounding text.

Response: Thank you for your meticulous reading. The indentation inconsistency in previous Line 553 has been corrected to match the formatting of the surrounding text.

14. Reviewer 1 (previous Line 562): Remove the extra period.

Response: Thank you for your careful review. The extra period in previous Line 562 has been removed to ensure proper punctuation.

Reviewer 2 Report

Comments and Suggestions for Authors

Review of: “Mooring Observations of Typhoon Trami (2024)-Induced Up- 2 per-Ocean Variability: Diapycnal Mixing and Internal Waves 3 Energy Characteristics” by Letian Chen, Ze Zhang, Xiaojiang Zhang, and Weimin Zhang Manuscript no. remotesensing-3735814

 General comments

This paper reports a detailed analysis of meteorological, mooring and remote sensing data, as well as meteorological and tidal model output recorded during the passage of Typhoon Trami close to the above mooring in the South China Sea, in October 2024.

The paper is well written and the analysis is remarkably complete, well exploiting the available information.

I do have the following conceptual questions, though, which I would like the Authors to address before publishing the paper.

Also, in the next section I suggest corrections to the text.

Line 163. "the residual current variations were divided into NIWs [(0.85, 1.20) f]": briefly describe how this was done.

Lines 230-2. "The difference in sea surface salinity...on October 26 and October 21 (Figure 3d)". Since the SSS data mentioned are 8-day moving averages, how was it possible to to compute the difference between two single days, i.e. Oct 26 and 21? Are also daily SSS data available? If so, mention them in Materials and methods.

Line 234. Same comment: how can you have instantaneous salinity data at 00:00 on Oct 26, when the salinity data are 8-day moving averages?

Lines 239-43. Do you have GPM precipitation data to show here? It would be appropriate to prove your statement.

Line 260-2. "This rising of the thermocline and deepening of the mixed layer": from Fig. 4a the rise of the thermocline is well visible, but not the deepening of the mixed layer. You should add a line for the mixed layer depth, using one of the standard criteria (temperature or density difference). Also, the thermocline seems not to disappear but goes very near to the surface... so how can the mixed layer deepen if the thermocline is not destroyed?

Line 290-1. "The signal of stronger velocity appeared at a depth of about 250 m." This sentence is not clear: I see that the stronger velocity is present in almost the entire water column (Fig. 5). Pls comment/correct.

Lines 478-80. "The positive change could be attributed to upwelling, which brings cold water to the near-surface, increasing density and enhancing stratification." What I see is, yes, an increase in N2 at depth, but with a value less than the more surface pre-storm max. Next, usually upwelling brings less stratified water to the surface (removing the lighter surface layer). So I don't think stratification is enhanced, but maybe simply the pycnocline is weaker and has moved down after mixing and/or upwelling. By the way, if it were only upwelling then the main effect would be the (quasi-inviscid) isopycnal uplifting, with little mixing, so you would see the deep stratification transferred upwards. In sum, I'm not sure if the post-storm N2 profile is due to upwelling, but I may be wrong of course. Comments?

Particular comments

I have gone through the entire MS and below are my particular suggested corrections.

Abstract

OK.

1. Introduction

 

Line 40. Replace "Satellite data (Aquarius/SMOS) show cyclones" with "Satellite data (Aquarius/SMOS) show that cyclones"

Line 48. Replace "a dynamic response was also" with "dynamic responses are also"

Lines 49. Replace "of which is near-inertial" with "of which is represented by near-inertial". By the way, are these surface or internal waves? Include "surface" or "internal" in the statement.

Line 74. Replace "from NIWs and internal tides to" with "from NIWs and internal tides (ITs) to"

Line 84. Replace "toward small-scale" with "towards small-scale"

Line 89. Replace "Typhoon Trami’s (202420)" with " Typhoon Trami’s (2024)"

Line 102. Replace "red pentagram" with "red star"

Line 102-3. Replace "The background shaded color and contour lines represented water depth." with "Colors and contour lines represent depth"

Fig. 1 caption, in general, replace "represented" with "represents"

Fig. 1 caption, please describe  K1/2 and O1/2 and what are the green and yellow points (STS and TY)

Fig. 1. if possible include a small inset with a more general map and a rectangle of the location of the area depicted in the figure (a benefit for readers not too familiar with the location). Also, name Hainan island in the map.

2. Materials and methods

 2.1. Data

 2.1.1 Mooring

 Line 102. Replace " was established" with " was deployed"

Line 112. Replace "red pentagram" with "red star"

Line 117. Replace "thermistor chain" with "instrument chain" (it is not only made of thermistors)

2.1.2. TC Best Track and Wind Data

Line 124. Replace "on its track" with "on their track" (is it one typhoon or more than one?)

2.2. Methods

 2.2.1  Stability and Energy Estimates

 Line 150. Replace "rho0 is the water density" with "rho is the water density"

Line 165. Replace "Besides, the" with "Also, the"

 2.2.2 Energy Transfer Rate

 Line 170. Replace "near-inertial and high-frequency" with " near-inertial (NIW) and high-frequency (HFIW)"

Line 174. Replace "of energy transfer" with "of energy transfer g"

Line 176. Replace "followed as" with "given by"

Lines 181-2. Replace "The vertical velocity is calculated by the displacement of the isotherms [6]. The vertical velocity can be inferred from the vertical displacement of isotherms [43];"

with

"Vertical velocity w' is calculated from the displacement of the isotherms [6], [43];"

Lines 183-4. "This equation has been employed to compute the energy transfer rate.". Sentence not needed.

Line 184. replace "Besides, to investigate" with "In order to investigate"

Line 186. "low-pass filtering". Could you specify the cutoff frequencies?

3. Results

 3.1. Upper Ocean Thermal and Dynamical Response

OK

3.1.1 Satellite-observed Sea Surface Response

Line 197. Replace "Consequently, Typhoon" with "Consequently, the typhoon"

Line 219. Replace "pentagram" with "star" and "represented" with "represents" throughout the caption.

Line 226. Replace "different from" with "differently from"

Line 228. Replace "8 day" with "8-day"

Line 248. Replace "pentagram" with "star" and "represented" with "represents" throughout the caption.

 3.1.2. Mooring-observed Subsurface Response

Line 262. Replace "increase" with "shoaling"

Line 268. Replace "can continue until" with "is seen to continue until"

Line 271-2. " Furthermore,... as recorded by the mooring". Not clear: do you have mixing and dissipation data to show?

Lines 275-7. Replace "Depth-time maps of the temperature anomaly. The solid black line represents the -2°C anomaly contour. The vertical black dashed lines represent the time when the typhoon was closest to the mooring station. The initial temperature was the three-day average from October 20 to 22"

with

"Depth-time maps of the temperature anomaly with respect to the October 20-22 average (is it an average profile?). The solid black line represents the -2°C anomaly contour. The vertical black dashed lines represent the time when the typhoon was closest to the mooring station."

Question: is it the Oct. 20-22 average profile (it looks like it) or is it an overall single value? Please specify.

Lines 279-80. Replace "eastward current component and northward current component at 50-300 m, respectively" with "eastward and northward current components at 50-300 m, respectively"

Lines 280-1. Replace "For the eastward velocity, the mooring observed a significant increase in velocity" with "The mooring observed a significant increase in eastward velocity"

Line 290. Replace "endure for around" with "persist for about"

3.2. The Mixing Processes and Driving Factors of the Upper Ocean

OK

3.2.1. Enhanced Diapycnal Mixing in the Upper Ocean Following the Typhoon

Line 336. Replace "in the around 50 m" with "at about 50 m"

Line 343. Replace "strong wind introduced by typhoon" with " the typhoon's strong wind"

Line 350. Replace "reestablish, residual strong shear" with "reestablish, a residual strong shear"

Line 363. Replace "of shear squared" with "of the shear"

3.2.2. Contribution of NIWs to the Upper Ocean Shear Instability

Lines 370-1. Replace "calculated by the following: firstly," with "calculated as follows. Firstly,"

3.3. Characteristics of Internal Wave Energy Distribution

3.3.1. The Temporal Evolution of NIWs Kinetic Energy

Line 406. Replace "over time" with "over time (Figure 9a)"

Line 407. Replace "concentrated in depths" with "concentrated at depths"

Line 411. Replace "near-surface energy" with "near-surface energy occurring around Nov. 2" (if I have understood well)

Line 427. Replace "subsurface seawater" with "subsurface waters"

3.3.2. Decomposition of Near-inertial Energy

OK

3.3.3. Depth Profiles of Time-averaged Internal Waves Kinetic Energy

OK

3.4. Burst of Subsurface-Layer Diurnal Tide Energy

3.4.1. The Modulation of Stratification Change

Line 493. Replace "to the more dissipation" with "to more dissipation"

Lines 508-9. "equations (5) and (6)". Eqn. (6) is missing. Or are you citing Eqns. (5) and (6) present in reference [53]? If so, replace with "equations (5) and (6) of [53]"

4. Discussion and Conclusions

Line 531. Replace "scarce" with "rare"

Line 533. Replace "Besides" with "Moreover"

Line 535. Replace "its energy" with "their energy"

Line 536. Replace "diurnal tidal capacity" with "diurnal tide"

Line 538. Replace "that generated" with "that the typhoon generated"

Line 541-3. "The mooring observation also reveals that the temperature decrease of 4°C, which is accompanied by the deepening of the mixed layer and the uplift of the thermocline." Incomplete sentence? (by the way, wasn't the decrease 2.5 C?)

Line 543. Replace "Besides" with "Also"

Line 545. Replace "periodic" with "periodicity"

Line 548. Replace "about 9 days" with "about 9 days in our case"

Comments on the Quality of English Language

The englieh is quite adequate, but needs some minor corrections. (see my particular comments)

Author Response

Response to Reviewer 2 Comments

We greatly appreciate the detailed and valuable comments from the reviewers on our manuscript. These comments are not only invaluable for revising and enhancing the paper but also provide important guidance for our research. Over the past five days, we have reviewed relevant literature, revised, and restructured the manuscript to improve its quality. 

Below, we summarize the revisions made in response to the comments on the previous version of the manuscript. We are grateful to the editors and reviewers for their dedicated efforts and time spent on reviewing the manuscript, and we hope the revised version will meet with your approval.

General comments and responses:

1. Reviewer 2: This paper reports a detailed analysis of meteorological, mooring and remote sensing data, as well as meteorological and tidal model output recorded during the passage of Typhoon Trami close to the above mooring in the South China Sea, in October 2024.

The paper is well written and the analysis is remarkably complete, well exploiting the available information.

Response: We sincerely appreciate the reviewer’s valuable comments regarding the clarity of our research questions and their connection to the study’s objectives. We have carefully revised both scientific questions to better reflect our research focus.

2. Reviewer 2: previous Line 163. “the residual current variations were divided into NIWs [(0.85, 1.20) f]”: briefly describe how this was done.

Response: Thank you for your comment on methodological clarity. The residual current variations were processed by first removing the barotropic current component from the TPXO9 dataset, then isolating NIWs within [(0.85, 1.20) f] (f = local inertial frequency) using a third-order Butterworth filter. The revised text is as follows: “After removing the barotropic current component from the TPXO9 dataset, the residual current variations were divided into NIWs within the frequency band [(0.85, 1.20) f] using a third-order Butterworth filter, where f denotes the local inertial frequency.” (Lines 163–166)

3. Reviewer 2: previous Lines 230-2. “The difference in sea surface salinity...on October 26 and October 21 (Figure 3d)”. Since the SSS data mentioned are 8-day moving averages, how was it possible to to compute the difference between two single days, i.e. Oct 26 and 21? Are also daily SSS data available? If so, mention them in Materials and methods.

Response: Thank you for your insightful comment regarding the calculation of sea surface salinity differences. The SSS difference is computed using 8-day running averages centered on October 26 and October 21 (Figure 3d), as clarified in the revised text: “The difference in sea surface salinity attributable to the typhoon is determined by calculating the difference between the 8-day running average salinity values centered on October 26 and October 21 (Figure 3d).” (Lines 232–234) Daily SSS data are not available for this analysis.

4. Reviewer 2: previous Line 234. Same comment: how can you have instantaneous salinity data at 00:00 on Oct 26, when the salinity data are 8-day moving averages?

Response: Thank you for your comment. To clarify, the reference to “Oct. 26” refers to the center date of its 8-day averaging window, not instantaneous data, as revised: “Conversely, on Oct. 26—the center date of its 8-day averaging window—a significant decline in sea surface salinity exceeding 2 psu was observed at the center of the typhoon (Figure 3b).”(Lines 236-238) No instantaneous salinity data are available; our analysis relies on the 8-day averaging window data.

5. Reviewer 2: previous Lines 239-43. Do you have GPM precipitation data to show here? It would be appropriate to prove your statement.

Response: Thank you for your suggestion. We did not utilize GPM precipitation data in this study, and the relevant content has been removed in the revised version to eliminate redundant information.

6. Reviewer 2: previous Line 260-2. “This rising of the thermocline and deepening of the mixed layer”: from Fig. 4a the rise of the thermocline is well visible, but not the deepening of the mixed layer. You should add a line for the mixed layer depth, using one of the standard criteria (temperature or density difference). Also, the thermocline seems not to disappear but goes very near to the surface... so how can the mixed layer deepen if the thermocline is not destroyed?

Response: Thank you for your careful reading. To clarify, we have added a line indicating the mixed layer depth (red solid line) in Figure 4b, using the standard temperature difference criterion, which better supports our conclusion about the deepening of the mixed layer. This addition clearly shows the mixed layer deepening alongside the thermocline rise, addressing your observation.

Regarding your question of how the mixed layer can deepen when the thermocline is not destroyed but only rises close to the surface, we appreciate this opportunity to clarify the physical context. Notably, the gray solid line in the figure solely represents the position of the 20°C isotherm and does not indicate that the thermocline has been destroyed. As demonstrated in previous studies [1,2], typhoon passage is typically accompanied by the upward displacement of isotherms and deepening of the mixed layer—a dynamic consistent with our observations here. To clarify this further, we have revised the relevant text to: “The upward movement of isotherms and deepening of the mixed layer are primarily attributed to mixing and advection processes caused by the typhoon’s passage.” (Lines 262-264) We believe this revision better articulates the physical process and resolves potential ambiguities.

References:

1. Lu, X.; Dong, C.; Zhang, H.; Lim Kam Sian, K.T.C.; Yang, J.; Xu, Z.; Li, G.; Wang, Q.; Cao, Q.; You, Z.; et al. Observational Analysis of Vertical Heat Flux Caused by Typhoon‐Induced Near‐Inertial Waves Under the Modulation of Mesoscale Eddies. JGR Oceans 2024, 129, doi:10.1029/2024jc021053.
2. Jarugula, S.L.; McPhaden, M.J. Ocean Mixed Layer Response to Two Post‐Monsoon Cyclones in the Bay of Bengal in 2018. JGR Oceans 2022, 127, doi:10.1029/2022JC018874.

7. Reviewer 2: previous Line 290-1. “The signal of stronger velocity appeared at a depth of about 250 m.” This sentence is not clear: I see that the stronger velocity is present in almost the entire water column (Fig. 5). Pls comment/correct.

Response: Thank you for your astute comment. We apologize for the ambiguity in the original statement. Upon re-evaluating Fig. 5 confirms stronger velocity signals span most of the water column, with a distinct enhancement above 250 m. The revised text: “Stronger velocity signals were observed throughout most of the water column, with a notable enhancement shallower than 250 m (Figure 5).” (Lines 293-295) now clarifies this, addressing your concern.

8. Reviewer 2: Lines 478-80. “The positive change could be attributed to upwelling, which brings cold water to the near-surface, increasing density and enhancing stratification.” What I see is, yes, an increase in N2 at depth, but with a value less than the more surface pre-storm max. Next, usually upwelling brings less stratified water to the surface (removing the lighter surface layer). So I don't think stratification is enhanced, but maybe simply the pycnocline is weaker and has moved down after mixing and/or upwelling. By the way, if it were only upwelling then the main effect would be the (quasi-inviscid) isopycnal uplifting, with little mixing, so you would see the deep stratification transferred upwards. In sum, I'm not sure if the post-storm N2 profile is due to upwelling, but I may be wrong of course. Comments?

Response: Thank you for your meticulous reading and professional insights, which have helpfully identified ambiguities in our original description. Your observation is well-founded: our initial statement had inaccuracies. The upper ocean stratification undergoes complex changes under typhoon influence—while typhoon-induced upwelling lifts the thermocline, it does not inherently enhance stratification; instead, stratification changes likely result from superimposed effects like mixing and upwelling, as you noted.

To clarify, we have revised the text to focus on the typhoon’s impact on upper ocean stratification (rather than overinterpreting the mechanism), strengthening coherence with subsequent discussions on internal wave energy adjustments via WKB theory. The revised content reads: “These processes disrupt the upper ocean’s stratification: seawater buoyancy frequency dropped in the top 60 m but rose around 80 m (Figure 12a). Such wind-induced stratification changes reshape near-inertial and internal tidal energy vertical distributions, causing refraction and energy adjustments [76]. Since internal waves are highly sensitive to local stratification, their amplitude and energy continuously adapt during propagation [73,74].” (Lines 480-485)

We appreciate your guidance in refining the precision of our analysis.

References:

73. Guan, S.; Zhao, W.; Huthnance, J.; Tian, J.; Wang, J. Observed Upper Ocean Response to Typhoon Megi (2010) in the Northern South China Sea. J. Geophys. Res. Oceans 2014, 119, 3134–3157, doi:10.1002/2013JC009661.
74. Leaman, K.D.; Sanford, T.B. Vertical Energy Propagation of Inertial Waves: A Vector Spectral Analysis of Velocity Profiles. Journal of Geophysical Research (1896-1977) 1975, 80, 1975–1978, doi:10.1029/JC080i015p01975.
75. Xu, Z.; Yin, B.; Hou, Y.; Xu, Y. Variability of Internal Tides and Near‐inertial Waves on the Continental Slope of the Northwestern South China Sea. Journal of Geophysical Research: Oceans 2013, 118, 197–211, doi:10.1029/2012JC008212, 2013.

Particular comments and responses:

1. Reviewer 2: I have gone through the entire MS and below are my particular suggested corrections.

Response: We appreciate the reviewer’s comprehensive review and constructive feedback. We have carefully considered all your suggestions throughout the manuscript.

2. Reviewer 2: Line 40. Replace “Satellite data (Aquarius/SMOS) show cyclones” with “Satellite data (Aquarius/SMOS) show that cyclones”

Response: Thank you for highlighting this. We have revised the sentence as suggested: “Satellite data (Aquarius/SMOS) show that cyclones...”.

3. Reviewer 2: Line 48. Replace “a dynamic response was also” with “dynamic responses are also”

Response: We appreciate this correction. The sentence now reads: “dynamic responses are also...”

4. Reviewer 2: Lines 49. Replace “of which is near-inertial” with “of which is represented by near-inertial”. By the way, are these surface or internal waves? Include “surface” or “internal” in the statement.

Response: Thank you for your valuable suggestions. We have revised the relevant content in line 49 as advised: we replaced “of which is near-inertial” with “of which is represented by near-inertial” and added “internal” to specify the wave type, as near-inertial waves in the upper ocean are typically internal waves.

5. Reviewer 2: Line 74. Replace “from NIWs and internal tides to” with “from NIWs and internal tides (ITs) to”

Response: We appreciate the reviewer’s valuable comments. We have added the abbreviation as suggested: “from NIWs and internal tides (ITs) to...”

6. Reviewer 2: Line 84. Replace “toward small-scale” with “towards small-scale”

Response: Thank you for noting the spelling inconsistency in previous Line 84. “Toward small-scale” has been revised to “towards small-scale” as recommended.

7. Reviewer 2: Line 89. Replace “Typhoon Trami’s (202420)” with “Typhoon Trami’s (2024)”

Response: We are grateful for catching the error. “Typhoon Trami’s (202420)” has been corrected to “Typhoon Trami’s (2024)” as suggested.

8. Reviewer 2: Line 102. Replace “red pentagram” with “red star”

Response: Thank you for the comment. “Red pentagram” has been changed to “red star” to improve clarity.

9. Reviewer 2: Line 102-3. Replace “The background shaded color and contour lines represented water depth.” with “Colors and contour lines represent depth”

Response: We appreciate the reviewer’s suggestion to simplify the description in previous Lines 102–103. The sentence has been revised to “Colors and contour lines represent depth” as recommended.

10. Reviewer 2: Fig. 1 caption, in general, replace “represented” with “represents”

Response: Thank you for pointing out the tense inconsistency in the Fig. 1 caption. “Represented” has been replaced with “represents” throughout the caption.

11. Reviewer 2: Fig. 1 caption, please describe K1/2 and O1/2 and what are the green and yellow points (STS and TY)

Response: Thank you for your feedback on the Fig. 1 caption. We have revised it to include descriptions of K1/2 and O1/2, and clarified the symbols: “K1/2 and O1/2 respectively denote the critical values at which the local effective frequency reaches that of the diurnal tides.” The green and yellow points, as noted in the text, denote STY (Super Typhoon) and TY (Typhoon), respectively. This revision addresses the clarity of the caption as highlighted.

12. Reviewer 2: Fig. 1. if possible include a small inset with a more general map and a rectangle of the location of the area depicted in the figure (a benefit for readers not too familiar with the location). Also, name Hainan island in the map.

Response: Thank you for suggesting improvements to Fig. 1. We have included a small inset map with a rectangular indicator of the study area and labeled Hainan Island to aid reader orientation.

13. Reviewer 2:Line 102. Replace “was established” with “was deployed”

Response: We appreciate the reviewer’s comment on previous Line 102. “Was established” has been revised to “was deployed” to better reflect the context.

14. Reviewer 2: Line 112. Replace “red pentagram” with “red star”

Response: Thank you for the consistency check in previous Line 112. “Red pentagram” has been changed to “red star” to align with earlier revisions.

15. Reviewer 2: Line 117. Replace “thermistor chain” with “instrument chain” (it is not only made of thermistors)

Response: We are grateful for noting that “thermistor chain” in previous Line 117 is imprecise. It has been corrected to “instrument chain” to acknowledge the broader composition of the equipment.

16. Reviewer 2: Line 124. Replace “on its track” with “on their track” (is it one typhoon or more than one?)

Response: Thank you for your note on previous Line 124. We would like to clarify that only one typhoon is discussed in this context. Since the reference is to a single typhoon, “on its track” remains appropriate, and thus we have not revised it to “on their track” as suggested. We appreciate your attention to this detail.

17. Reviewer 2: Line 150. Replace “rho0 is the water density” with “rho is the water density”

Response: We appreciate the reviewer’s attention to terminology in previous Line 150. “Rho0” has been changed to “rho” to accurately refer to water density.

18. Reviewer 2: Line 165. Replace “Besides, the” with “Also, the”

Response: Thank you for the stylistic suggestion in previous Line 165. “Besides, the” has been revised to “Also, the” for better flow.

19. Reviewer 2: Line 170. Replace “near-inertial and high-frequency” with “near-inertial (NIW) and high-frequency (HFIW)”

Response: We are grateful for the abbreviation suggestion in previous Line 170. The text has been updated to “near-inertial (NIW) and high-frequency (HFIW)” to improve readability.

20. Reviewer 2: Line 174. Replace “of energy transfer” with “of energy transfer g”

Response: Thank you for catching the omission in previous Line 174. “Of energy transfer” has been corrected to “of energy transfer g” as recommended.

21. Reviewer 2: Line 176. Replace “followed as” with “given by”

Response: We appreciate the reviewer’s comment on previous Line 176. “Followed as” has been replaced with “given by” to enhance precision.

22. Reviewer 2: Lines 181-2. Replace “The vertical velocity is calculated by the displacement of the isotherms [6]. The vertical velocity can be inferred from the vertical displacement of isotherms [43];”

with

“Vertical velocity w is calculated from the displacement of the isotherms [6], [43];”

Response: Thank you for simplifying the text in previous Lines 181–182. The sentence has been revised to “Vertical velocity w' is calculated from the displacement of the isotherms [6,43];” as suggested.

23. Reviewer 2: Lines 183-4. “This equation has been employed to compute the energy transfer rate.”. Sentence not needed.

Response: We are grateful for noting the redundancy in previous Lines 183–184. The sentence “This equation has been employed to compute the energy transfer rate” has been removed as recommended.

24. Reviewer 2: Line 184. replace “Besides, to investigate” with “In order to investigate”

Response: Thank you for the stylistic suggestion in previous Line 184. “Besides, to investigate” has been revised to “In order to investigate” for better clarity.

25. Reviewer 2: Line 186. “low-pass filtering”. Could you specify the cutoff frequencies?

Response: We appreciate the reviewer’s question about the low-pass filtering cutoff in previous Line 186. We have added specific cutoff frequencies (“1.1 cpd”) to clarify the method.

26. Reviewer 2: Line 197. Replace “Consequently, Typhoon” with “Consequently, the typhoon”

Response: Thank you for the pronoun correction in previous Line 197. “Consequently, Typhoon” has been revised to “Consequently, the typhoon” for consistency.

27. Reviewer 2: Line 219. Replace “pentagram” with “star” and “represented” with “represents” throughout the caption.

Response: We are grateful for the caption revisions suggested in previous Line 219. “Pentagram” has been changed to “star” and “represented” to “represents” throughout the caption.

28. Reviewer 2: Line 226. Replace “different from” with “differently from”

Response: Thank you for the preposition correction in previous Line 226. “Different from” has been revised to “differently from” as recommended.

29. Reviewer 2: Line 228. Replace “8 day” with “8-day”

Response: We appreciate the hyphenation suggestion in previous Line 228. “8 day” has been corrected to “8-day” for grammatical accuracy.

30. Reviewer 2: Line 248. Replace “pentagram” with “star” and “represented” with “represents” throughout the caption.

Response: Thank you for the consistency check in previous Line 248. “Pentagram” has been changed to “star” and “represented” to “represents” in the caption, aligning with earlier revisions.

31. Reviewer 2: Line 262. Replace “increase” with “shoaling”

Response: We sincerely appreciate the reviewer’s valuable comments. We are grateful for the terminology suggestion in previous Line 262. “Increase” has been replaced with “shoaling” to better describe the process.

32. Reviewer 2: Line 268. Replace “can continue until” with “is seen to continue until”

Response: We sincerely appreciate the reviewer’s valuable comments. Thank you for the precision suggestion in previous Line 268. “Can continue until” has been revised to “is seen to continue until” to reflect observational evidence.

33. Reviewer 2: Line 271-2. “Furthermore, ... as recorded by the mooring”. Not clear: do you have mixing and dissipation data to show?

Response: Thank you for your comment. Regarding mixing processes, we have analyzed them using Richardson number (Ri) plots in Section 3.2. The original statement was removed as its conclusion lacked rigor; this revision aims to avoid redundancy and enhance logical coherence.

34. Reviewer 2: Lines 275-7. Replace “Depth-time maps of the temperature anomaly. The solid black line represents the -2°C anomaly contour. The vertical black dashed lines represent the time when the typhoon was closest to the mooring station. The initial temperature was the three-day average from October 20 to 22”

with

“Depth-time maps of the temperature anomaly with respect to the October 20-22 average (is it an average profile?). The solid black line represents the -2°C anomaly contour. The vertical black dashed lines represent the time when the typhoon was closest to the mooring station.”

Question: is it the Oct. 20-22 average profile (it looks like it) or is it an overall single value? Please specify.

Response: We sincerely appreciate the reviewer’s valuable comments. Thank you for clarifying the temperature anomaly reference in previous Lines 275–277. The caption has been revised to specify that the anomaly is relative to the three-day average temperature profile (October 20–22), as confirmed.

35. Reviewer 2: Lines 279-80. Replace “eastward current component and northward current component at 50-300 m, respectively” with “eastward and northward current components at 50-300 m, respectively”

Response: We sincerely appreciate the reviewer’s valuable comments. We are grateful for simplifying the text in previous Lines 279–280. The phrase has been revised to “eastward and northward current components at 50–300 m, respectively” as suggested.

36. Reviewer 2: Lines 280-1. Replace “For the eastward velocity, the mooring observed a significant increase in velocity” with “The mooring observed a significant increase in eastward velocity”

Response: We sincerely appreciate the reviewer’s valuable comments. Thank you for streamlining the sentence in previous Lines 280–281. It has been revised to “The mooring observed a significant increase in eastward velocity” for conciseness.

37. Reviewer 2: Line 290. Replace “endure for around” with “persist for about”

Response: We sincerely appreciate the reviewer’s valuable comments. We appreciate the synonym suggestion in previous Line 290. “Endure for around” has been replaced with “persist for about” to improve flow.

38. Reviewer 2: Line 336. Replace “in the around 50 m” with “at about 50 m”

Response: We sincerely appreciate the reviewer’s valuable comments. Thank you for correcting the preposition in previous Line 336. “In the around 50 m” has been revised to “at about 50 m” as recommended.

39. Reviewer 2: Line 343. Replace “strong wind introduced by typhoon” with “the typhoon's strong wind”

Response: We sincerely appreciate the reviewer’s valuable comments. We are grateful for rephrasing previous Line 343 for clarity. “Strong wind introduced by typhoon” has been corrected to “the typhoon’s strong wind” as suggested.

40. Reviewer 2: Line 350. Replace “reestablish, residual strong shear” with “reestablish, a residual strong shear”

Response: We sincerely appreciate the reviewer’s valuable comments. Thank you for catching the article omission in Line 350. “Reestablish, residual strong shear” has been revised to “reestablish, a residual strong shear” for grammatical accuracy.

41. Reviewer 2: Line 363. Replace “of shear squared” with “of the shear”

Response: We sincerely appreciate the reviewer’s valuable comments. We appreciate the simplification suggestion in previous Line 363. “Of shear squared” has been replaced with “of the shear” as recommended.

42. Reviewer 2: Lines 370-1. Replace “calculated by the following: firstly,” with “calculated as follows. Firstly,”

Response: We sincerely appreciate the reviewer’s valuable comments. Thank you for the punctuation correction in previous Lines 370–371. The text has been revised to “calculated as follows. Firstly,” for better readability.

43. Reviewer 2: Line 406. Replace “over time” with “over time (Figure 9a)”

Response: We sincerely appreciate the reviewer’s valuable comments. We are grateful for the figure reference suggestion in previous Line 406. “Over time” has been updated to “over time (Figure 9a)” to guide readers.

44. Reviewer 2: Line 407. Replace “concentrated in depths” with “concentrated at depths”

Response: We sincerely appreciate the reviewer’s valuable comments. Thank you for the preposition correction in previous Line 407. “Concentrated in depths” has been revised to “concentrated at depths” as suggested.

45. Reviewer 2: Line 411. Replace “near-surface energy” with “near-surface energy occurring around Nov. 2” (if I have understood well)

Response: We sincerely appreciate the reviewer’s valuable comments. We appreciate the specificity suggestion in Line 411. “Near-surface energy” has been clarified to “near-surface energy occurring around Nov. 2” as recommended.

46. Reviewer 2: Line 427. Replace “subsurface seawater” with “subsurface waters”

Response: We sincerely appreciate the reviewer’s valuable comments. Thank you for the terminology suggestion in Line 427. “Subsurface seawater” has been replaced with “subsurface waters” for conciseness.

47. Reviewer 2: Line 493. Replace “to the more dissipation” with “to more dissipation”

Response: We sincerely appreciate the reviewer’s valuable comments. We are grateful for removing the redundant article in previous Line 493. “To the more dissipation” has been corrected to “to more dissipation” as suggested.

48. Reviewer 2: Lines 508-9. “equations (5) and (6)”. Eqn. (6) is missing. Or are you citing Eqns. (5) and (6) present in reference [53]? If so, replace with “equations (5) and (6) of [53]”

Response: We sincerely appreciate the reviewer’s valuable comments. Thank you for clarifying the equation reference in previous Lines 508–509. Since only Eqn. (5) is used, the text has been revised to “equations (5) of [53]” to avoid confusion.

49. Reviewer 2: Line 531. Replace “scarce” with “rare”

Response: We sincerely appreciate the reviewer’s valuable comments. We appreciate the synonym suggestion in previous Line 531. “Scarce” has been replaced with “rare” for better precision.

50. Reviewer 2: Line 533. Replace “Besides” with “Moreover”

Response: We sincerely appreciate the reviewer’s valuable comments. Thank you for the transition word suggestion in previous Line 533. “Besides” has been revised to “Moreover” to improve flow.

51. Reviewer 2: Line 535. Replace “its energy” with “their energy”

Response: We sincerely appreciate the reviewer’s valuable comments. We are grateful for the pronoun correction in previous Line 535. “Its energy” has been changed to “their energy” to agree with the plural subject.

52. Reviewer 2: Line 536. Replace “diurnal tidal capacity” with “diurnal tide”

Response: We sincerely appreciate the reviewer’s valuable comments. Thank you for clarifying the terminology in Line 536. “Diurnal tidal capacity” has been revised to “diurnal tide” as recommended.

53. Reviewer 2: Line 538. Replace “that generated” with “that the typhoon generated”

Response: We sincerely appreciate the reviewer’s valuable comments. We appreciate the specificity suggestion in previous Line 538. “That generated” has been clarified to “that the typhoon generated” to identify the source.

54. Reviewer 2: Line 541-3. “The mooring observation also reveals that the temperature decrease of 4°C, which is accompanied by the deepening of the mixed layer and the uplift of the thermocline.” Incomplete sentence? (by the way, wasn't the decrease 2.5 C?)

Response: We appreciate you pointing out the incomplete sentence in previous previous Lines 541–543, which has been revised to: “The mooring data indicate that the maximum temperature drop of 4°C occurs on Oct. 28, coinciding with the deepening of the mixed layer and the rise of the thermocline.” (Lines 544–546) 

To clarify, the 4°C temperature drop reflects instantaneous observations from the mooring, distinct from the 2.5°C value derived from satellite-based daily average data. This discrepancy arises from the different temporal resolutions of the two data sources, and we apologize for any earlier ambiguity.

55. Reviewer 2: Line 543. Replace “Besides” with “Also”

Response: We sincerely appreciate the reviewer’s valuable comments. We are grateful for the transition word suggestion. “Besides” has been replaced with “Also” for consistency.

56. Reviewer 2: Line 545. Replace “periodic” with “periodicity”

Response: We sincerely appreciate the reviewer’s valuable comments. Thank you for the noun form suggestion in previous Line 545. “Periodic” has been revised to “periodicity” to correct the part of speech.

57. Reviewer 2: Line 548. Replace “about 9 days” with “about 9 days in our case”

Response: We sincerely appreciate the reviewer’s valuable comments. We appreciate the contextual clarification in previous Line 548. “About 9 days” has been updated to “about 9 days in our case” as recommended.

Comments on the Quality of English Language:

Reviewer 2: The English is quite adequate, but needs some minor corrections. (see my particular comments)

Response: We thank the reviewer for their assessment of the English language. All minor corrections noted in the specific comments have been implemented to enhance the clarity and accuracy of the text.

 

 

Author Response File: Author Response.pdf