A Numerical Study of Near Inertial Motions in Mid-Atlantic Bight Area Induced by Hurricane Irene (2011)

Han, Peida; Yu, Xiping

doi:https://doi.org/10.5194/egusphere-2022-635

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https://doi.org/10.5194/egusphere-2022-635

Preprints

18 Jul 2022

| 18 Jul 2022

A Numerical Study of Near Inertial Motions in Mid-Atlantic Bight Area Induced by Hurricane Irene (2011)

Peida Han and Xiping Yu

Abstract. Hurricane Irene generated strong near inertial currents (NICs) in the ocean waters when passing over the Mid-Atlantic Bight (MAB) of the U. S. East Coast in late August 2011. It is demonstrated that a combination of the valuable field data with detailed model results can be exploited to study the development and decay mechanism of this event. Numerical results obtained with regional oceanic modeling system (ROMS) are shown to agree well with the field data. Both computed and observed results show that the NICs were significant in most areas of the MAB region except in the nearshore area where the stratification was totally destroyed by the hurricane-induced strong mixing. Based on the energy budget, it is clarified that the near inertial kinetic energy (NIKE) was mainly gained from the wind power during the hurricane event. In the deep water region, NIKE was basically balanced by the vertical turbulence diffusion (40 %) and downward divergence (33 %). While in the continental shelf region, NIKE was mainly dissipated by the vertical turbulence diffusion (67 %) and partially by the bottom friction (24 %). Local dissipation of NIKE due to turbulence diffusion is much more closely related to the rate of the vertical shear rather than the intensity of turbulence. The strong vertical shear at the offshore side of the continental shelf leaded to a rapid dissipation of NIKE in this region.

Received: 12 Jul 2022 – Discussion started: 18 Jul 2022

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Journal article(s) based on this preprint

01 Nov 2022

A numerical study of near-inertial motions in the Mid-Atlantic Bight area induced by Hurricane Irene (2011)

Peida Han and Xiping Yu

Ocean Sci., 18, 1573–1590, https://doi.org/10.5194/os-18-1573-2022,https://doi.org/10.5194/os-18-1573-2022, 2022

Short summary

Peida Han and Xiping Yu

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2022-635', Anonymous Referee #1, 15 Aug 2022

A good and timely study about properties of inertial waves.

What I miss is a more detailed description of the used boundary layer model (line 106) and how the definitions of its variables

relate to the analysis. Related to that is the rather poor Figure 5. Getting observed and modelled NIWs right requires good forcing

and a good ML model. So please highlight and enlarge important panels of Fig 5, come up with a metric (eg difference in NI EKE), and

discuss differences - if any.

Citation: https://doi.org/10.5194/egusphere-2022-635-RC1
- AC1: 'Reply on RC1', Xiping Yu, 12 Sep 2022
  
  Please see attached.
  
  Citation: https://doi.org/10.5194/egusphere-2022-635-AC1
- AC3: 'Reply on RC1', Xiping Yu, 12 Sep 2022
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-635/egusphere-2022-635-AC3-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2022-635-AC3
RC2:
'Comment on egusphere-2022-635', Anonymous Referee #2, 18 Aug 2022

Overall an interesting paper on an important topic with a storm that has become a wonderful test case for coastal ocean storm interactions. The study is well formed and remains largely focused on storm induced inertial currents. Some minor additions and edits are required, including a more detailed and distinct methods section for the observational data utilized. While the data was generaelly publicly available, more details on how the authors treated the data for QAQC, or what default QAQC if any they used from the downloaded data is required.

Specific line-by-line Comments:

Line 32 - 35 - while an interesting comment it is disconnected from the current article.

Line 96 - Caroline should be Carolina

Line 99 - What was the vertical gradient in temperature? This is likely more important than the surface/bottom temperature difference.

Line 102 - Schofield et al., 2010 is a reference for Slocum gliders generally, however there are multiple references for the Hurricane Irene specifically (Glenn et al., 2016) being the most prominent.

There is no clear methods/data section, with some of the observational data described within what looks like results sections.

Line 234 - Why is the effective depth assumed to be 2.4m? Is there a reference for this?

Line 236 - Is the accuracy of HF Radar here referring to this dataset in particular or more generally? A more recent publication from Roarty et al., on HF Radar in the region can be found here: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020JC016368

Line 239 - 264 Were tides removed from the HF Radar fields and model current fields? I believe later in the paper they were, but it’s not clear what was done for this spatial analysis.

Line 266 - 274 - Please comment on data QAQC, Glider setup details, or where this information can be found e.g. previous publications or where it was downloaded. I’m assuming it was from the IOOS Glider DAC? Also an additional paper on Hurricane Irene mixing from glider and ROMS data was detailed here https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017JC012756

And a detailed exploration of pre-storm mixing was carried out by Watkins and Whitt here: https://journals.ametsoc.org/view/journals/phoc/50/12/jpo-d-20-0134.1.xml

Line 290 - 301 How did the maximum N-squared values compare between the observations and glider? It appears in Figure 3c and 3d that the observed N-squared was significantly greater than in the model ahead of the deepening and mixing, but similar during the deepening event?

Line 314 - I’m not clear on the use of the Zhang reference here. Is this referring to tropical cyclone shallow water mixing generally?

Line 315 - Caroline should be Carolina

Line 315 - 316 - Over what time-scale did the SST recover to pre-hurricane levels? Off North Carolina there was likely very little Cold Pool water, thus mixing should result in very little cooling. Plots of bottom. Temperature pre-storm from the model will likely show this.

Line 323 - I agree that the model/data mismatches are largely not too critical for the process investigations presented here. I think the strength of stratification is likely the most important model feature to validate as it can affect the vertical mixing and generation/dissipation of NIC.

Line 342 - 343 - Were data dropouts documented, or could there be dynamical reason that the NIC are in poorer agreement offshore? The HF Radar data should include quality flags to identify missing or low quality data.

Line 378 -381 - Is the 75m D3 location the beginning of the shelf-break front, a mesoscale feature impinging on the shelf, or simply too far from the main track? Adding the reference lines to additional spatial figures would be helpful doer interpretation rather than needing to flip back to figure 1 for the reader.

Citation: https://doi.org/10.5194/egusphere-2022-635-RC2
- AC2: 'Reply on RC2', Xiping Yu, 12 Sep 2022
  
  Please see attached.
  
  Citation: https://doi.org/10.5194/egusphere-2022-635-AC2
- AC4: 'Reply on RC2', Xiping Yu, 12 Sep 2022
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-635/egusphere-2022-635-AC4-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2022-635-AC4
EC1:
'Comment on egusphere-2022-635', Karen J. Heywood, 13 Sep 2022

Thank you for your responses in the online discussion. I look forward to receiving your revised paper, which should be uploaded to the Ocean Sciences Copernicus portal as explained in the emails you will have received.
Karen

Citation: https://doi.org/10.5194/egusphere-2022-635-EC1
- AC5: 'Reply on EC1', Xiping Yu, 14 Sep 2022
  
  Thank you very much for your instructions. We shall upload the revised manuscript as yuou required.
  
  Citation: https://doi.org/10.5194/egusphere-2022-635-AC5

Interactive discussion

Status: closed

RC1:
'Comment on egusphere-2022-635', Anonymous Referee #1, 15 Aug 2022

A good and timely study about properties of inertial waves.

What I miss is a more detailed description of the used boundary layer model (line 106) and how the definitions of its variables

relate to the analysis. Related to that is the rather poor Figure 5. Getting observed and modelled NIWs right requires good forcing

and a good ML model. So please highlight and enlarge important panels of Fig 5, come up with a metric (eg difference in NI EKE), and

discuss differences - if any.

Citation: https://doi.org/10.5194/egusphere-2022-635-RC1
- AC1: 'Reply on RC1', Xiping Yu, 12 Sep 2022
  
  Please see attached.
  
  Citation: https://doi.org/10.5194/egusphere-2022-635-AC1
- AC3: 'Reply on RC1', Xiping Yu, 12 Sep 2022
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-635/egusphere-2022-635-AC3-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2022-635-AC3
RC2:
'Comment on egusphere-2022-635', Anonymous Referee #2, 18 Aug 2022

Overall an interesting paper on an important topic with a storm that has become a wonderful test case for coastal ocean storm interactions. The study is well formed and remains largely focused on storm induced inertial currents. Some minor additions and edits are required, including a more detailed and distinct methods section for the observational data utilized. While the data was generaelly publicly available, more details on how the authors treated the data for QAQC, or what default QAQC if any they used from the downloaded data is required.

Specific line-by-line Comments:

Line 32 - 35 - while an interesting comment it is disconnected from the current article.

Line 96 - Caroline should be Carolina

Line 99 - What was the vertical gradient in temperature? This is likely more important than the surface/bottom temperature difference.

Line 102 - Schofield et al., 2010 is a reference for Slocum gliders generally, however there are multiple references for the Hurricane Irene specifically (Glenn et al., 2016) being the most prominent.

There is no clear methods/data section, with some of the observational data described within what looks like results sections.

Line 234 - Why is the effective depth assumed to be 2.4m? Is there a reference for this?

Line 236 - Is the accuracy of HF Radar here referring to this dataset in particular or more generally? A more recent publication from Roarty et al., on HF Radar in the region can be found here: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020JC016368

Line 239 - 264 Were tides removed from the HF Radar fields and model current fields? I believe later in the paper they were, but it’s not clear what was done for this spatial analysis.

Line 266 - 274 - Please comment on data QAQC, Glider setup details, or where this information can be found e.g. previous publications or where it was downloaded. I’m assuming it was from the IOOS Glider DAC? Also an additional paper on Hurricane Irene mixing from glider and ROMS data was detailed here https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017JC012756

And a detailed exploration of pre-storm mixing was carried out by Watkins and Whitt here: https://journals.ametsoc.org/view/journals/phoc/50/12/jpo-d-20-0134.1.xml

Line 290 - 301 How did the maximum N-squared values compare between the observations and glider? It appears in Figure 3c and 3d that the observed N-squared was significantly greater than in the model ahead of the deepening and mixing, but similar during the deepening event?

Line 314 - I’m not clear on the use of the Zhang reference here. Is this referring to tropical cyclone shallow water mixing generally?

Line 315 - Caroline should be Carolina

Line 315 - 316 - Over what time-scale did the SST recover to pre-hurricane levels? Off North Carolina there was likely very little Cold Pool water, thus mixing should result in very little cooling. Plots of bottom. Temperature pre-storm from the model will likely show this.

Line 323 - I agree that the model/data mismatches are largely not too critical for the process investigations presented here. I think the strength of stratification is likely the most important model feature to validate as it can affect the vertical mixing and generation/dissipation of NIC.

Line 342 - 343 - Were data dropouts documented, or could there be dynamical reason that the NIC are in poorer agreement offshore? The HF Radar data should include quality flags to identify missing or low quality data.

Line 378 -381 - Is the 75m D3 location the beginning of the shelf-break front, a mesoscale feature impinging on the shelf, or simply too far from the main track? Adding the reference lines to additional spatial figures would be helpful doer interpretation rather than needing to flip back to figure 1 for the reader.

Citation: https://doi.org/10.5194/egusphere-2022-635-RC2
- AC2: 'Reply on RC2', Xiping Yu, 12 Sep 2022
  
  Please see attached.
  
  Citation: https://doi.org/10.5194/egusphere-2022-635-AC2
- AC4: 'Reply on RC2', Xiping Yu, 12 Sep 2022
  
  The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-635/egusphere-2022-635-AC4-supplement.pdf
  
  Citation: https://doi.org/10.5194/egusphere-2022-635-AC4
EC1:
'Comment on egusphere-2022-635', Karen J. Heywood, 13 Sep 2022

Thank you for your responses in the online discussion. I look forward to receiving your revised paper, which should be uploaded to the Ocean Sciences Copernicus portal as explained in the emails you will have received.
Karen

Citation: https://doi.org/10.5194/egusphere-2022-635-EC1
- AC5: 'Reply on EC1', Xiping Yu, 14 Sep 2022
  
  Thank you very much for your instructions. We shall upload the revised manuscript as yuou required.
  
  Citation: https://doi.org/10.5194/egusphere-2022-635-AC5

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

AR by Xiping Yu on behalf of the Authors (14 Sep 2022) Author's response Author's tracked changes Manuscript

ED: Publish subject to minor revisions (review by editor) (25 Sep 2022) by Karen J. Heywood

In general, I did not find your responses sufficiently convincing. In places your responses to the reviewers were detailed but the text added to the paper was minimal. Please ensure that information that the reviewers asked for is added to the paper.

Please could you revise Figures 3, 4, 7, and 10 to use a colour-blind-friendly colormap, i.e. not colormap jet in Matlab. There are plenty of colormaps available now that are more accessible to all. See for example this article from 2014 https://www.climate-lab-book.ac.uk/2014/end-of-the-rainbow/

Reviewer 1 asks for more information on the boundary layer (mixed layer) formulation that you use in ROMS. I do not think you have really answered this with the information provided in the paper. Your response is to repeat more detail of ROMS. What the reviewer is asking for is not to put information in the response, but to put information into the paper, exactly how the upper ocean boundary layer is treated in the model?

Reviewer 1 commented that Figure 5 (now Figure 6) was “rather poor” and asked you to “please highlight and enlarge important panels of Fig 5”. This figure looks the same to me. It needs improvement. Please highlight and enlarge important panels, and consider also plotting the differences between the lines.

Reviewer 1 also comments that you need a metric to determine how good the model is. You choose to use correlation. However two things could be perfectly correlated but orders of magnitude different. Therefore you need to come up with a different metric. I suggest you use the metric suggested by the reviewer – the difference in near-inertial EKE. You will need to add discussion of the differences in the paper.

Reviewer 2 asked that “While the data was generally publicly available, more details on how the authors treated the data for QAQC, or what default QAQC if any they used from the downloaded data is required.” While you have added a section describing the data, thank you, you did not mention any quality control. Did you simply download other people’s publicly available data and use them as they are? If so, you should say so clearly. Did you pay attention to any flags? Did you check the data for outliers etc? It is important to know exactly what *you* did. For example did you grid the data? Smooth or average them, in time and/or in space? You were not involved in the glider data acquisition or the HF radar acquisition I think, so you should make sure that those who did are clearly acknowledged and that you state in the text where and when you downloaded the data, what resolution or version you used, and what you did with the data.

Thank you for clarifying that you detided the model currents and the HF radar currents. Please can you state how you did this, with a reference if appropriate.
You added a mention of there being little Cold Pool water present, as the reviewer suggested. Could you expand on your text here please, to explain why little cold pool water leads to insignificant cooling and fast recovery?

Reviewer 2 says that “the strength of stratification is likely the most important model feature to validate”, but you have not validated this? Please could you quantify how well the model reproduces the observed strength of stratification, and add a discussion of this.

You have not really responded sufficiently to “Were data dropouts documented, or could there be dynamical reason that the NIC are in poorer agreement offshore? The HF Radar data should include quality flags to identify missing or low quality data.”. The question needs to be addressed – did you use the quality flags? You have responded with information about coverage, but what does this mean? Why was there low coverage? Or if you are simply downloading someone else’s data, what do the quality flags mean and how did you use them? Are there data dropouts? Are there dynamical reasons for poor agreement? This needs discussion in the paper, beyond the sentence you added.

Thank you for adding the extra figure showing the lines. However you have not added anything to the paper in response to “Is the 75m D3 location the beginning of the shelf-break front, a mesoscale feature impinging on the shelf, or simply too far from the main track?”. Please add some sentences to address this.

Hide

AR by Xiping Yu on behalf of the Authors (05 Oct 2022) Author's response Author's tracked changes

EF by Polina Shvedko (06 Oct 2022) Manuscript

ED: Publish as is (09 Oct 2022) by Karen J. Heywood

AR by Xiping Yu on behalf of the Authors (10 Oct 2022)

Journal article(s) based on this preprint

01 Nov 2022

A numerical study of near-inertial motions in the Mid-Atlantic Bight area induced by Hurricane Irene (2011)

Peida Han and Xiping Yu

Ocean Sci., 18, 1573–1590, https://doi.org/10.5194/os-18-1573-2022,https://doi.org/10.5194/os-18-1573-2022, 2022

Short summary

Peida Han and Xiping Yu

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Short summary

Hurricane Irene generated strong near inertial currents in the ocean waters when passing over the Mid-Atlantic Bight of the U. S. East Coast in late August 2011. It is demonstrated that a combination of the valuable field data with detailed model results can be exploited to study the development and decay mechanism of this event. The near inertial kinetic energy is shown to mainly gained from the wind power during the hurricane event. Its decay, however, depends on several factors.


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