Seasonal variation of the principal tidal constituents  in the Bohai Sea

Wang, Daosheng; Pan, Haidong; Jin, Guangzhen; Lv, Xianqing

doi:https://doi.org/10.5194/os-16-1-2020

Articles | Volume 16, issue 1

https://doi.org/10.5194/os-16-1-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/os-16-1-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 16, issue 1

Research article

|

06 Jan 2020

Research article |

| 06 Jan 2020

Seasonal variation of the principal tidal constituents in the Bohai Sea

Daosheng Wang, Haidong Pan, Guangzhen Jin, and Xianqing Lv

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Final revised paper (published on 06 Jan 2020)
Preprint (discussion started on 17 May 2019)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Review of os-2019-43: “Seasonal variation of the main tidal constituents in the Bohai Bay”', Anonymous Referee #1, 12 Jun 2019
- AC1: 'Interactive comment on “Seasonal variation of the principal tidal constituents in the Bohai Sea” by Daosheng Wang et al.', Daosheng Wang, 17 Aug 2019
RC2: 'review report', Anonymous Referee #2, 09 Jul 2019
- AC2: 'Interactive comment on “Seasonal variation of the principal tidal constituents in the Bohai Sea” by Daosheng Wang et al.', Daosheng Wang, 17 Aug 2019

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Daosheng Wang on behalf of the Authors (17 Aug 2019) Author's response Manuscript

ED: Reconsider after major revisions (05 Sep 2019) by Joanne Williams

AR by Daosheng Wang on behalf of the Authors (26 Sep 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (01 Oct 2019) by Joanne Williams

RR by Anonymous Referee #2 (19 Oct 2019)

Suggestions for revision or reasons for rejection

Comments on “Seasonal variation of the main tidal constituents in the Bohai Sea” by D. Wang et al.

This revised manuscript has eliminated the major problems contained in the original one, and thus can be published after minor revision given below:

1. Page 2, lines 24-25: Change “Hourly sea-level data at the Dalian tidal gauge station were obtained from the University of Hawaii Sea Level Center and used. After 1979, Dalian shared position with Laohutan (Feng et al., 2015)” to “Hourly sea-level data at the Dalian tidal gauge station used in this study were obtained from the University of Hawaii Sea Level Center. After 1979, the Dalian station is located at Laohutan (Feng et al., 2015)”.

2. Page 4, line 7: Change “oscillations” to “fluctuations”

3. Page 4, line 23: Delete “and near those estimated using CHA”, because the parameters derived from CHA do not have temporal variation, see Figure 4.

4. Page 5, lines 20-23: Change “The estimated harmonic parameters using both the SHA and EHA were near to those obtained using CHA, showing that the estimated results were reasonable. In addition, the estimated harmonic parameters obtained using EHA were much closer to those obtained using SHA for data from Dalian than those from E2” to “The averaged harmonic parameters estimated using both the SHA and EHA were close to those obtained using CHA, showing that the estimated results were reasonable. In addition, the estimated harmonic parameters obtained using EHA were much closer to those obtained using SHA for data at Dalian than those at E2”.

5. Page 7, lines 17-18: Change “The simulation area was the Bohai Sea as shown in Figure 1b” to “The simulation area of the Bohai Sea is shown in Figure 1b”.

6. Page 12, line 11: Change “Weiwen” to “Wenzheng”; change “Zhonzhu” to “Zongyong”.

7. Page 12, line 45: Replace “Accepted, 2018” with exact volume and page numbers, because this paper should have already been printed.

8. Page 14, Tables 1 and 2: Change all “phase” to “phase lag”, because in the literatures on ocean tides, “phase lag” is convectional used instead of “phase”.

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RR by Anonymous Referee #1 (25 Oct 2019)

Suggestions for revision or reasons for rejection

-OVERVIEW:
-This is my second review of this paper, which analyzes the seasonal variation of tidal constituents in the Bohai Sea, using data from a mooring as well as tide gauge data from Dalian. Additionally, the study includes some modelling work to help explain the observed seasonality. I believe that this work is important and interesting, as the non-astronomical seasonality of tides is an important topic. This effect has been examined in many locations, but to my knowledge, no other studies have looked specifically at the Bohai Sea, so this work is a welcome addition to the body of knowledge. This is especially true for this region of China, where there is not much publicly available tide gauge data to utilize. Furthermore, I think that the authors have done a good job of explaining the past efforts of previous studies, discussed well the possible mechanisms behind the observed seasonality, and have also performed some well-designed modelling experiments to back up their observations. Finally, this version is much improved from the first submission, and the majority of my initial concerns have been adequately covered, so I am very pleased with the current form of the paper, and believe it should be an important submission to help guide future investigations of tidal seasonality.
My recommendation for this paper is for acceptance, though I do have a small number of (mostly technical) comments and thoughts that I would like to see addressed first.

COMMENTS:
-In the abstract, you talk about the location of your mooring observations, which you give as “E2”. However, at this stage of the paper, the reader does not know what “E2” means, since you have not yet told us that this is the name given to your mooring location; this is described later. Therefore, in the abstract, you should instead just mention the approximate geographical location of the mooring observations, which should be something like “the western Bohai Sea”, or something similar. “E2” is just a shorthand indicator to tell us a bout a real location, so be clear about this in the abstract, and after you describe the exact location of “E2”, then you can rely on using the shorthand.
-I think that is good that you compare both the mooring data, which is a short record of about a year from 2013-2014, and the tide gauge data from Dalian/Laohutan from 1980-1997. As I have also tried working with the tide gauge data from Mainland China, and understand that there is not much recent publicly available data, the “historical” tide gauge records that all end in the 1997 are the only resources available to employ. However, I think that you should include some caveats in your discussion about the fact that these two sets of data come from different time eras, and that there might be a limit to have comparable the two data sets might be. In particular, there has ben some previous suggestions that some majot shifts in climate and sea level behavior occurred around 1998, roughly coinciding with the 1997-1998 El Nino event, and this “shift” may have changed many of the physical oceanic properties of the Western Pacific, especially things like sea level rates and upper-ocean warming, which both tended to increase quite a bit in the post-1998 era. I still think that your present comparison is valid, I am just saying that some mention about the time difference should be included.
-Please give a little more description about the combination of data from the Dalian and Laohutan data sets; saying they “shared position” does not seem to make sense, as these are two separate locations. Do you mean to say that the gauge was “relocated”, but the two locations are “close enough” to consider them to be combineable? UHSLC gives some history of the gauges and history in the metadata links of their data archives, and you should also be able to find some helpful information about each gauge from the PSMSL data overviews. For example, is there any reasons given as to why the gauges were moved, and did anyone validate their connections?
-In Section 4, where you discuss possible mechanisms, you might consider adding monsoon-related mechanisms as another possibility. Wind forcing changes, such as Ekman forcing and changes in geostrophic in forcing was shown to be possibly important by Devlin et al, 2018 in explaining the seasonality of the tides in SE Asia. Others might have found similar conclusions.
-A quick comment about section structure. Section 3 is labelled “Results”, but Section 4.2 is also labelled “Results”, which is a bit confusing. I think that maybe the latter instance refers to “Modelling Results”, so this might be a better title for this section.
-A final comment is just about the English grammar. This version is markedly improved from the first version, however, there are a small number of relatively minor grammar issues. It is probably OK as-is, but my gentle recommendation is that the author could do well by giving the grammar one more scan, and perhaps ask the help of a native English speaker or editing service to give it a close look. Cleaning up some of the minor issues with the grammar would improve this good paper even more.

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RR by Anonymous Referee #3 (27 Oct 2019)

Suggestions for revision or reasons for rejection

Major comments:
(1) I wonder why the authors use only E2 and Dalian data in this paper. In the Bahai Sea, there are other tide gauges such as QinghuangDao and Tanggu. It would be more convincing by analyzing ALL available data sets for exploring seasonal variability. In addition, I am not sure the SSH data at a cross-over point of satellite altimeter tracks in the central Bohai Sea is long enough for the seasonal study. At present, E2 and Dalian data are studied, but they have different lengths and qualities. Why not conduct a COMPLETE investigation using all these data sets?

(2) I found the four numerical experiments are problematic. Look at Figure 9, one cannot draw any solid conclusions about the effect of stratification and vertical viscosity coefficient. The numerical and observed results do not agree with each other in most cases. Thus, the authors' results, as described in section 4.2, are suggestive but not conclusive. The authors better design experiments that may lead to "conclusive" results.

(3) The citations are confusing. The authors do cite a lot of papers on this topic. But they just CITE them, not really digest them. For example, some results about seasonal variability are based on modeling work, with which the authors better be alert (e.g. Muller et al. 2014). Another example, P7 L76, this sentence, citing 4 papers, means nothing without details. Another example, P6 L30 says that seasonal ice coverage is a significant reason; while P7 L11 says that Zhang et al (2019) has rejected this effect.

(4) Throughout the paper, the tide names M2, S2, O1 and K1 are in italic font. They should be in normal font as M{sub{2}} and S{sub{2}}.

Minor comments:
(0) The writing is still not good. Your "language editor" can make sure your English grammar is correct. But he/she cannot guarantee that your writing is accurate, concise and conniving. It is beyond their capability.
(1) Please give us the longitude and latitude of E2.
(2) Some "scientific facts" better be in present tense, not past tense.
(3) P1 L14, "S2 and K1 tidal amplitudes" where 'tidal' can be omitted. Many such cases in this paper.
(4) In Introduction, Section 1, please start with the history and basic conclusions of the tide in the Bohai Sea, and lead to your motivating questions for this study.
(5) Since the major topic is the seasonality of tides in the Bohai Sea, please downscale the "Methods" part. Now your comparisons of CHA, TTIDE, UTIDE, EHA are overweighted. You authors have published 2 papers on this topic in 2018.
(6) P9 L8, Do Fang and Wang (1986) have any other data sets or results that you can cite and compare here?
(7) P10 L23, well-mixed
(8) P10 L29, "sea-level" throughout the paper, such a hyphen is not necessary.
(9) P11 L22, why does Shenzhen support a research in the Bohai Sea?
(10) Figure 2a, is the drop around 2013-12-1 caused by a winter storm? say it.
(11) Figure 3 and 5, can you plot two spectra, one for summer and one for winter? That is, can you see seasonal difference in spectra?
(12) Figure 5b, the O1 peak is below the 5% level (dashed line). Does it mean O1 is insignificant?
(13) Figure 6, why do you plot “multi-yearly values” and thus have large uncertainties (long vertical bars)? Can you simply divide the whole data set into 4 seasonal subsets and harmonic analysis on each of them? Like Figure 8b.
(14) Figure 10, Is your eastern boundary tide input stationary or seasonal variable? Because the Yellow Sea tide has a seasonality (some references you cited), will it affect your boundary condition?

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ED: Publish subject to minor revisions (review by editor) (29 Oct 2019) by Joanne Williams

AR by Daosheng Wang on behalf of the Authors (07 Nov 2019) Author's response Manuscript

ED: Publish subject to minor revisions (review by editor) (08 Nov 2019) by Joanne Williams

Dear Prof Wang and colleagues,

Thank-you for your recent revision (os-2019-43-manuscript-version6) and response to reviewers. The paper is considerably better than it started and is much clearer to read. I am satisfied in most respects that you have addressed the reviewers comments. However these still remain, and the first is a very important point.

Reviewer 3, point 2:
"2) I found the four numerical experiments are problematic. Look at Figure 9, one cannot draw
any solid conclusions about the effect of stratification and vertical viscosity coefficient. The
numerical and observed results do not agree with each other in most cases. Thus, the authors'
results, as described in section 4.2, are suggestive but not conclusive. The authors better design
experiments that may lead to "conclusive" results."

You have not addressed this sufficiently. I agree with the reviewer that the evidence presented at Dalian is really very weak, since the numerical experiments and observations are in very poor agreement, as shown in figures 9 and 10 and section 4.2. There is some evidence at E2 that favours Experiment 3.

The conclusion in P11 line 17, and the last line of the abstract are therefore not justified by the evidence you have presented.

It's OK to present a negative result, that you have tested various mechanisms and have not found any that reproduce the observations. But it must be made clearer in the discussion and also in the abstract. For example in the abstract:
"The results of numerical experiments indicate that the seasonality of vertical eddy viscosity induces seasonal variations of the principal tidal constituents at E2. However these mechanisms do not reproduce the observations at Dalian."

Reviewer 3, point 19:
You haven't addressed this. There needs to be an outer boundary somewhere, but it is not clear that the boundary should be the same for summer and winter. You could, for example, have calculated summer and winter boundaries using seasonal altimetry, for a 5th & 6th experiment. This is one of the other possible mechanisms for the observed result at Dalian and should be mentioned in the discussion.

You might also mention atmospheric variations as a possible mechanism at Dalian, particularly as you cannot reproduce the S2 change with your experiments.

Minor points:

Reviewer 3 (points 2 and 11) raised the data selection, but I accept your argument that you have used all the publicly available data, although this limits the study. You might consider adding a line in the discussion to this effect, to assist anyone trying to improve data availability.

Reviewer 3 (point 3) mentions the use of literature, which could be better. For example, P2 L2 you might rearrange as "There is a seasonal variability of the M 2 harmonic constants in the seas adjacent to Korea (Kang et al. 1995)", and similar for neighbouring sentences. Having done this, refocusing on the science rather than the scientist, the repetition should stand out, and you might condense it. However, this is a style point, and I don't insist on it.

I suggest you move the paragraph about ice (P7L10) to the previous section (P7L3), then this mechanism is dismissed before you start the experiments.

P3 L20: You don't state which constituents you have fitted in SHA. This is an important point for anyone attempting to reproduce your work, especially for this study. For example if MA2, MB2 were used, they may contain most of the seasonal modulation of M2, and M2 would not change. Please at least state the number of constituents fitted in the SHA and EHA at E2 and Dalian, and your model, and preferably list them (this can be in supplementary info if necessary).

P2 L30: I was curious as to what "nearby" meant so had to look it up from your grid reference in the reply to reviewer. I suggest
"As indicated in Feng et al. (2015), the stations at Dalian and Laohutan (7km away) have data ..."

P1line 13 "an enhanced..."

P3L26: Suggest:
"In contrast, the harmonic parameters are assumed to be constant in CHA and constant within each month in SHA."

P8L4: Why 0.2m when Figure 8 has 0.4m difference summer-winter?

P11 line 7: check the grammar.

p11 line 11: Do you mean it's semi-annual?
======================

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AR by Daosheng Wang on behalf of the Authors (17 Nov 2019) Author's response Manuscript

ED: Publish as is (20 Nov 2019) by Joanne Williams

AR by Daosheng Wang on behalf of the Authors (22 Nov 2019)

Short summary

This work investigates the seasonal variations of M₂, S₂, K₁, and O₁ at E2 and Dalian. At E2, the M₂ amplitude and phase lag reach maximum in summer and minimum in winter. The S2 and K1 amplitudes show annual cycles, while the phase lags of S₂, K₁, and O₁ had semi-annual cycles. The seasonal variations at Dalian are different from those at E2, except for M₂ phase lag. The seasonal variations at E2 are induced by seasonality of vertical eddy viscosity, while those at Dalian cannot be explained.