Some aspects of the deep abyssal overflow between the middle and southern basins of the Caspian Sea

Babagoli Matikolaei, Javad; Aliakbari Bidokhti, Abbasali; Shiea, Maryam

doi:https://doi.org/10.5194/os-15-459-2019

Articles | Volume 15, issue 2

https://doi.org/10.5194/os-15-459-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/os-15-459-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 2

Research article

|

29 Apr 2019

Research article |

| 29 Apr 2019

Some aspects of the deep abyssal overflow between the middle and southern basins of the Caspian Sea

Javad Babagoli Matikolaei, Abbasali Aliakbari Bidokhti, and Maryam Shiea

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Final revised paper (published on 29 Apr 2019)
Preprint (discussion started on 16 Feb 2018)

Interactive discussion

Status: closed

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

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RC1: 'Review of Matikolaei et al.: Some aspects of the deep abyssal overflow between the middle and southern basins of the Caspian Sea', Christopher W. Hughes, 11 May 2018
- AC1: 'Answer to Dr. C. W. Hughes', Javad Babagoli matikolaei, 25 Jun 2018
RC2: 'Review', Anonymous Referee #2, 31 May 2018
- AC2: 'Answer to Anonymous Referee #2', Javad Babagoli matikolaei, 25 Jun 2018

Peer-review completion

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

AR by Javad Babagoli matikolaei on behalf of the Authors (25 Jun 2018) Author's response Manuscript

ED: Reject (02 Jul 2018) by John M. Huthnance

Dear Authors. Thank-you for uploading your revised version. However, I regret to say that (after all this revision effort over two submissions) I conclude that I have to reject your manuscript. I am sorry that this will be a disappointment.

Several of the detailed comments by both reviewers have not been corrected in the latest revision (even where they could have been or you say they have been; a few are listed below). More seriously, it is still not clear what is really being learned that may be of interest to the wider Ocean Science readership. Although there is now a little more testing of the results of the three analytical models for the flow, these three models are still “not clearly differentiated to explain how/where they are expected to apply”. This is a crucial factor in the relevance of this work to a wider readership. There is a vague reference (page 14 line 3) to a “different dynamic” as a reason for the second rather than the first model. However, nothing is said about how the dynamics are different and I do not see any more physics in the second model than in the first.

The question about comparison of winter and summer temperature ranges not corresponding between text and figure 1 caused me to look at Ibrayev et al. (2010). This actually seems to be a modelling study quite similar to yours, which rather devalues your COHERENS run, except that they run a repeating year 1982 rather than your use of 2004 from a 2000-2004 run. Are the large differences between text and figure 1 the result of different time-interval/averaging or differences between years? You could compare with the differences between years in these runs to test this.

You should think seriously about the above and indeed all the reviewer comments if you wish to submit again somewhere. You also need to remember that a paper published in Ocean Science is accompanied by all (reviewer and other) comments at all stages.

Detailed comments (NOT comprehensive)

Figure 2 left. Coastline unclear. Figure 2 right. The two outlined parts are not on quite the same scale and the coastlines differ.

Figure 4. This still has unhelpful background colour. How many CTD casts were used to form these figures? According to the longitudes (c.f. figure 2), the right-hand part of this section is on land.

Page 7 line 18. I cannot understand this sentence.

Page 12 lines 42, 43 and elsewhere. Please not “1/s” but “s” with a superscript “-1”

Page 13 line 4. As Ri = 3.1, Table 1 equation 1 cannot be used. Certainly (line 5) Ri > 0.08 but what is the significance of “0.08”?

Page 15 section 3.2. What are the assumptions here and how do they compare with the assumptions in section 3.1?

Page 16 lines 5-6. “∂h/∂x is slope of isopycnals”. If more than one isopycnal there may be more than one slope but there is only one value ∂h/∂x. So what decides the choice of isopycnal. Is the water above at rest?

Page 18 top line. Delete “flow entrainments near its boundaries due to”

Page 19 Figure 6 or 7 caption needs to remind the reader which transects are observations and which are model outputs – and if model output, which model?

Page 20 line 16. Delete “The numerical model (figure 9) confirms this prediction.”

Hide

ED: Reconsider after major revisions (05 Jul 2018) by John M. Huthnance

Dear Authors. Thank-you for uploading your revised version. However, I regret to say that (after all this revision effort over two submissions) it still needs "major revision" in my opinion.
Several of the detailed comments by both reviewers have not been corrected in the latest revision (even where they could have been or you say they have been; a few are listed below). More seriously, it is still not clear what is really being learned that may be of interest to the wider Ocean Science readership. Although there is now a little more testing of the results of the three analytical models for the flow, these three models are still “not clearly differentiated to explain how/where they are expected to apply”. This is a crucial factor in the relevance of this work to a wider readership. There is a vague reference (page 14 line 3) to a “different dynamic” as a reason for the second rather than the first model. However, nothing is said about how the dynamics are different and I do not see any more physics in the second model than in the first.

The question about comparison of winter and summer temperature ranges not corresponding between text and figure 1 caused me to look at Ibrayev et al. (2010). This actually seems to be a modelling study quite similar to yours, which rather devalues your COHERENS run, except that they run a repeating year 1982 rather than your use of 2004 from a 2000-2004 run. Are the large differences between text and figure 1 the result of different time-interval/averaging or differences between years? You could compare with the differences between years in these runs to test this.

You should think seriously about the above and indeed all the reviewer comments. You also need to remember that a paper published in Ocean Science is accompanied by all (reviewer and other) comments at all stages.

Detailed comments (NOT comprehensive)

Figure 2 left. Coastline unclear. Figure 2 right. The two outlined parts are not on quite the same scale and the coastlines differ.

Figure 4. This still has unhelpful background colour. How many CTD casts were used to form these figures? According to the longitudes (c.f. figure 2), the right-hand part of this section is on land.

Page 7 line 18. I cannot understand this sentence.

Page 12 lines 42, 43 and elsewhere. Please not “1/s” but “s” with a superscript “-1”

Page 13 line 4. As Ri = 3.1, Table 1 equation 1 cannot be used. Certainly (line 5) Ri > 0.08 but what is the significance of “0.08”?

Page 15 section 3.2. What are the assumptions here and how do they compare with the assumptions in section 3.1?

Page 16 lines 5-6. “∂h/∂x is slope of isopycnals”. If more than one isopycnal there may be more than one slope but there is only one value ∂h/∂x. So what decides the choice of isopycnal? Is the water above at rest?

Page 18 top line. Delete “flow entrainments near its boundaries due to”

Page 19 Figure 6 or 7 caption needs to remind the reader which transects are observations and which are model outputs – and if model output, which model?

Page 20 line 16. Delete “The numerical model (figure 9) confirms this prediction.”

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AR by Javad Babagoli matikolaei on behalf of the Authors (13 Sep 2018) Author's response

ED: Referee Nomination & Report Request started (20 Sep 2018) by John M. Huthnance

RR by Anonymous Referee #2 (11 Oct 2018)

Suggestions for revision or reasons for rejection

This manuscript discusses the overflow of the title via some observations of temperature and salinity, a long run of a 3-D numerical model, with some check against a relatively short period of current measurements (not in the overflow) and temperature and salinity fields, and two analytical models. The latter depend on the numerical model results for some input.

The topic – overflow - is of some interest, more widely than the Caspian Sea if the approach here could be used elsewhere.

I think there is still some lack of clarity about the purpose of the whole paper, and certainly about the role of the two analytic models. Fair comment is made that with paucity of observational data, models are wanted to increase the information/evidence available. Given the dependence of the analytical models on some input from the numerical model, what is their added value? There are 2 or more possibilities.
1) Analytical models may need less observational data as input than would a 3-D numerical model. I don’t think this is stated although there is mention that the methods may help where there is paucity of observations.
2) Comparison with the numerical model might indicate that the simplifying assumptions in an analytic model are valid. This could lead to an understanding of the most important dynamics involved. Such an advance is mentioned in passing but there is no demonstration of a good match between numerical and analytical model results, which in any case might be “forced” by the initial input of numerical model information to the analytical model.

The following detailed comments include many instances where the intended meaning or logic is not made clear.
Page 1
Line 18. For what reason?
Line 24. Does “this work” refer to Falcini and Salusti (2015) or the present manuscript?

Page 2.
Line 3. “thermocline” should be “thermohaline”?
Lines 3-5. I think this sentence could be omitted given the following sentence.
Line 13. “near shelves” should be “near-shelf”

Page 5.
Line 16. Better “. . very coarse for showing the overflow. . .”
Line 19. “high regulation” should be “fine-resolution”.

Page 6 lines 23-24. This sentence lacks some logic. The purpose of running the model is the lack of observational data. The ADCP data are not for the last year but only for three months according to line 21. The sentence seems to imply that the purpose of running the model is to check the accuracy of its performance, but that is not the main reason in the rest of the manuscript.

Page 7 lines 21-22. This sentence is very unclear. Do you mean that the simulations and the observations both confirm the existence of a deep flow in Absheron Strait? (Figure 4.)?

Page 9.
Lines 11-14. This should have a reference to literature, or is it a result of the numerical model? Please clarify.
Lines 31-32. This looks much like lines 12-13.

Page 10
Top line. Better “. . of the overflow is about . .”
Figure 8 caption, last line. “similar” as regards depth, but not the slope.

Page 12.
Lines 5-6 and 11-13. These are at present divided by equations (4) but should be brought together and put in logical order. Please state the line 12 “input parameters” – g’, up, vp but not the others in Table 2?
Line 14. Figure 11 is transect II further downstream. How does this contribute to the input parameters?

Page 13 figure 10. The letters should be larger and the part with the coordinates should be larger.

Page 15 lines 16-17. Unclear logic; why should the method (what method) depend on N-S direction of flow?

Page 16
Line 23. I do not understand “stirring diffusion”. Maybe “stirring and diffusion” or just one of the two.
Lines 27-28. “. . In this paper, it is shown that the dense water is firstly formed . .”. No! it is stated several times but not shown in this manuscript.
Lines 33-34. This sentence seems out of place. There are a few sentences like this that might best be brought together in an “impacts” sub-section.

Page 17
Line 5. I do not understand “changes in flow in its perpendicular direction”. The three directions are vertical, along-flow or across-flow (= lateral).
Line 6. Not “because the ventilation could be addressed”. Maybe “for their influence on ventilation”?
Lines 12-13. “we need to use an analytical model” is not convincing when there are numerical model results.
Line 19. “They” – is this Falcini and Salusti? Needs to be stated because the present implication is Whitehead et al.

Page 18.
Line 3. “receptively” should be “respectively”
Lines 22, 23. The symbol for PV should be in italics.
Line 29. “because the depth of water is changing . . (stretching term)” applies to vorticity but NOT to potential vorticity.

Page 19.
There should be a reference somewhere to figure 16.
Lines 18, 19, 20. “Nov.” should be “November”
Line 29. Not “over the cape”. Maybe “north of the cape”?

Page 21.
Line 13. Delete “an increase in”
Line 17. “which does not account for mixing in the momentum equation”. But you have E*.
Lines 18-19. This sentence is very unclear. Perhaps this is my point 2 near the top of my comments.
Line 20. “it” -> “vorticity”. However, this does not explain why the analytic model rather than the numerical model is used. There is a statement about this on line 22 but it is very weak. From where do you get the value of ζo ?
Lines 25 to 30 are confusing. You mix discussion of the first model (lines 25, 27) with discussion of the second (lines 26-27, 28-30). You say (no) “approximation such as balancing between forces” but (a) any momentum equation is a balance between forces, (b) your first model has zero pressure gradient, (c) the Falcini and Salusti (2015) model neglects time-dependence. Also lines 28-30 need to be clearer that you are discussing the model that you used. Line 30 “in our method” needs to be clear that it is the second model.
Line 31. “on their assumption” – what assumption.
Line 35. ζ not ξ
Line 36. “. . between the two . .”

Page 22.
Line 5. Better “southern basin entrainment is negligible (due . .”
Line 22. I think you substituted equations (8) as integration limits in equation (7). What “assumptions”?

Page 23.
Lines 3-5 “If we assume . . we have . . (10)” No! (10) is an approximation assuming L1 = L2. Lines 8-10 do not explain this properly. I think the difference between (10) and the accurate value of Qv depends on α and L2/L1 (at least, possibly other variables as well).
Lines 26-27. This sentence is unclear. If there were a special contour for each month, why would Qv be calculated “under the same conditions for all months”?
Line 27 to top of page 24. If the flushing time is estimated based on the . . numerical simulations, what is the purpose of equations (8) to (10)? Perhaps you mean “. . is also estimated . .”. Which method is used for the values in Table 4?

Page 25.
Line 9. I think this section might be “Conclusions and consequences” (or some similar extra word) because you discuss impacts which are not really conclusions of your study (page 26 lines 3 - 9).
Lines 13-17. These are probably true but not really conclusions of your study.

Hide

ED: Reconsider after major revisions (15 Oct 2018) by John M. Huthnance

Dear Authors
Please see the referee's comments as copied below.
Yours sincerely
John Huthnance

The topic – overflow - is of some interest, more widely than the Caspian Sea if the approach here could be used elsewhere.

I think there is still some lack of clarity about the purpose of the whole paper, and certainly about the role of the two analytic models. Fair comment is made that with paucity of observational data, models are wanted to increase the information/evidence available. Given the dependence of the analytical models on some input from the numerical model, what is their added value? There are 2 or more possibilities.
1) Analytical models may need less observational data as input than would a 3-D numerical model. I don’t think this is stated although there is mention that the methods may help where there is paucity of observations.
2) Comparison with the numerical model might indicate that the simplifying assumptions in an analytic model are valid. This could lead to an understanding of the most important dynamics involved. Such an advance is mentioned in passing but there is no demonstration of a good match between numerical and analytical model results, which in any case might be “forced” by the initial input of numerical model information to the analytical model.

The following detailed comments include many instances where the intended meaning or logic is not made clear.
Page 1
Line 18. For what reason?
Line 24. Does “this work” refer to Falcini and Salusti (2015) or the present manuscript?

Page 2.
Line 3. “thermocline” should be “thermohaline”?
Lines 3-5. I think this sentence could be omitted given the following sentence.
Line 13. “near shelves” should be “near-shelf”

Page 5.
Line 16. Better “. . very coarse for showing the overflow. . .”
Line 19. “high regulation” should be “fine-resolution”.

Page 6 lines 23-24. This sentence lacks some logic. The purpose of running the model is the lack of observational data. The ADCP data are not for the last year but only for three months according to line 21. The sentence seems to imply that the purpose of running the model is to check the accuracy of its performance, but that is not the main reason in the rest of the manuscript.

Page 7 lines 21-22. This sentence is very unclear. Do you mean that the simulations and the observations both confirm the existence of a deep flow in Absheron Strait? (Figure 4.)?

Page 9.
Lines 11-14. This should have a reference to literature, or is it a result of the numerical model? Please clarify.
Lines 31-32. This looks much like lines 12-13.

Page 10
Top line. Better “. . of the overflow is about . .”
Figure 8 caption, last line. “similar” as regards depth, but not the slope.

Page 12.
Lines 5-6 and 11-13. These are at present divided by equations (4) but should be brought together and put in logical order. Please state the line 12 “input parameters” – g’, up, vp but not the others in Table 2?
Line 14. Figure 11 is transect II further downstream. How does this contribute to the input parameters?

Page 13 figure 10. The letters should be larger and the part with the coordinates should be larger.

Page 15 lines 16-17. Unclear logic; why should the method (what method) depend on N-S direction of flow?

Page 16
Line 23. I do not understand “stirring diffusion”. Maybe “stirring and diffusion” or just one of the two.
Lines 27-28. “. . In this paper, it is shown that the dense water is firstly formed . .”. No! it is stated several times but not shown in this manuscript.
Lines 33-34. This sentence seems out of place. There are a few sentences like this that might best be brought together in an “impacts” sub-section.

Page 17
Line 5. I do not understand “changes in flow in its perpendicular direction”. The three directions are vertical, along-flow or across-flow (= lateral).
Line 6. Not “because the ventilation could be addressed”. Maybe “for their influence on ventilation”?
Lines 12-13. “we need to use an analytical model” is not convincing when there are numerical model results.
Line 19. “They” – is this Falcini and Salusti? Needs to be stated because the present implication is Whitehead et al.

Page 18.
Line 3. “receptively” should be “respectively”
Lines 22, 23. The symbol for PV should be in italics.
Line 29. “because the depth of water is changing . . (stretching term)” applies to vorticity but NOT to potential vorticity.

Page 19.
There should be a reference somewhere to figure 16.
Lines 18, 19, 20. “Nov.” should be “November”
Line 29. Not “over the cape”. Maybe “north of the cape”?

Page 21.
Line 13. Delete “an increase in”
Line 17. “which does not account for mixing in the momentum equation”. But you have E*.
Lines 18-19. This sentence is very unclear. Perhaps this is my point 2 near the top of my comments.
Line 20. “it” -> “vorticity”. However, this does not explain why the analytic model rather than the numerical model is used. There is a statement about this on line 22 but it is very weak. From where do you get the value of ζo ?
Lines 25 to 30 are confusing. You mix discussion of the first model (lines 25, 27) with discussion of the second (lines 26-27, 28-30). You say (no) “approximation such as balancing between forces” but (a) any momentum equation is a balance between forces, (b) your first model has zero pressure gradient, (c) the Falcini and Salusti (2015) model neglects time-dependence. Also lines 28-30 need to be clearer that you are discussing the model that you used. Line 30 “in our method” needs to be clear that it is the second model.
Line 31. “on their assumption” – what assumption.
Line 35. ζ not ξ
Line 36. “. . between the two . .”

Page 22.
Line 5. Better “southern basin entrainment is negligible (due . .”
Line 22. I think you substituted equations (8) as integration limits in equation (7). What “assumptions”?

Page 23.
Lines 3-5 “If we assume . . we have . . (10)” No! (10) is an approximation assuming L1 = L2. Lines 8-10 do not explain this properly. I think the difference between (10) and the accurate value of Qv depends on α and L2/L1 (at least, possibly other variables as well).
Lines 26-27. This sentence is unclear. If there were a special contour for each month, why would Qv be calculated “under the same conditions for all months”?
Line 27 to top of page 24. If the flushing time is estimated based on the . . numerical simulations, what is the purpose of equations (8) to (10)? Perhaps you mean “. . is also estimated . .”. Which method is used for the values in Table 4?

Page 25.
Line 9. I think this section might be “Conclusions and consequences” (or some similar extra word) because you discuss impacts which are not really conclusions of your study (page 26 lines 3 - 9).
Lines 13-17. These are probably true but not really conclusions of your study.

Hide

AR by Anna Wenzel on behalf of the Authors (03 Jan 2019) Author's response

ED: Referee Nomination & Report Request started (04 Jan 2019) by John M. Huthnance

RR by Anonymous Referee #3 (08 Mar 2019)

ED: Publish subject to minor revisions (review by editor) (18 Mar 2019) by John M. Huthnance

Dear authors
I now have the referee comments on your latest manuscript. I am sorry for the delay with these. You should improve the figures as they ask. [Also figure 6 is fuzzy]. Also I have many comments to make about the text which I think could be much improved. Some general points:

There is much repetition. You need to decide your structure (the present structure is OK) and then decide, for everything you write, where it should go. I have some detailed comments below but there are other places with repetition etc.

Be explicit. There are many places with “this” but I cannot tell what “this” refers to. Replace “this” with the subject that it refers to.

There are several sections which just have too many words without a clear “message”. I mention some below but you need to think about this throughout.

In view of these points I think I should see the manuscript again after you have revised it.

Detailed comments
Page 1.
Lines 19-21. Better “. . we use the analytic model of Falcini and Salusti (2015) for the overflow gravity current to estimate the changes of vorticity and potential vorticity of the flow over the Absheron sill; the effects of entrainment . .”
Line 26. “. . moves over these wells. . .”?

Page 3
Lines 3-4. Not “. . convection can lead to . . convection . .”. What do you mean by “thermocline convection”?
Line 6. “to investigate” is very vague. And you don’t “investigate the existence of deep abyssal overflow”; you state its presence as a fact based on previous studies.
Line 12. Better “. . as there has been only a little research on this deep flow . .”
Line 13. “. . results compared with . .”
Line 16. “In section 4 . .”
Line 17. “simple formula. Following this section, it is clarified why . .”. What is “this approach”?

Lines 24-25. “in this project . . Hajef.” Is Hajef the project name or the ship name? If the ship name, what project?
Line 31. “. . between the two basins . .”
Line 35. Not “sensible”; maybe “detailed”? “parameters” -> “variables”

Page 6 line 25. “. . of the last year . .”

Page 7
Line 21. “. . indicated that deep flow . .”
Line 22. “. . show that deep flow . .”

Page 9
Line 12. “. . basin (Fig. 10a), . .”
Line 18. “. . differences are . .”
Line 32. “. . 1992 and . .”
Line 34. “. . justifies a geostrophic assumption for flow entering . .”

Page 10 lines 28-29. “. . 10a. Varying initial conditions for deep flow probably lead to . .”

Page 11
Line 9. “different” -> “varying”
Lines 13-14. This sentence is confusing. Why not choose 1008.8 and include November as well?
Line 16. “rather than” -> “compared with”
Line 20. “more near” -> “confined closer”
Line 23. “filling” (spelling)
Lines 27-28. “. . that were in . .” Is there something missing, e.g. where were the waters that you discuss here?
Line 28. Not “slinked”. Maybe “sunk”?
Page 11 line 20 to page 12 line 11. This is a lot of text but it is not clear what is their real message? Too many words means confusion not a clear message. Please consider carefully and reduce to what you really want to say.

Page 12 line 4. “4” -> “5”.

Page 14
Line 6. “being” -> “is”.
Line 16. “. . from that coast and . .”
Lines 16-18. Is this sentence relevant? Possibly, if line 19 “the previous work” is Ezam et al. 2012 about the Persian Gulf. If so, please be explicit that “the previous work” is Ezam et al. 2012.
Line 23. “. . important in . .”
Line 33. You need to define rb. At least you need rb ≡ . . but some text would help. What is “u”?

Page 15 line 5. You need to define re and say what it is.

Page 16.
Lines 3-9. There is much repetition here of the text before section 3.1. These lines 3-9 are better merged in to the text before 3.1.
Lines 14-15 “whereas . . 1974)” Omit?
Line 21. Omit “two”.
Equations (1) and (2). How does E relate to E*? How does r relate to rb and re?

Page 17.
Line 12. “based on formulas” – there is no formula for re!
Lines 26-27. Better “. . vorticity is the least among the months shown. When it comes . .” NB “and also . . transect III” is repetition.

Page 18.
Line 5. “are changing” –> “changes”
Line 7. “. . appears as a trapped current . .”
Line 16. “20 km (I) to 35 km (V), . .”
Line 18. “. . (Fig. 14) . .”?
Lines 19-20. How does Fig. 17 show “eddies”? do you mean Fig. 15?
Lines 29-30. Better “. . radius of deformation RD = (g’H)^0.5/f (based on . . . upstream). Based on Fig. 13 . .” [i.e. move the formula]

Page 20.
Lines 6-22. This is a lot of text but it is not clear what is their real message? Too many words means confusion not a clear message. Please consider carefully and reduce to what you really want to say.
Lines 9-10. I agree with Eq.(3) but this sentence says something different.
Line 11. “It means that” implies a logical connection between the previous text to the following text. I don’t see the connection.
Line 12. “This is” – what is?
Line 20. “. . need of ADCP data. . .”
Line 21. “. . like Absheron Strait. Thus . .” [no need to refer to Hormuz].
Line 21. “this method” – what method. Maybe omit this sentence?
Lines 31-32. “speed is assumed constant” – do you mean constant in time and/or uniform in depth?

Page 21.
Equations (5), (6). The denominator is (L2+L1) in (5), (L2-L1) in (6); I think one of these is wrong.
For (6) do you assume L1^2 = L2^2 – you should say so?
Line 14. In figure 16 L1 is negative but not in line 14.
Lines 14-17. What is the real message of these two sentences? They repeat some earlier text. Too many words means confusion not a clear message. Please consider carefully and reduce to what you really want to say.
Line 20. “and use of” -> “,”

Page 22.
Lines 4-10. Too many words. Repetition of section 2.3 page 11.
Line 15. Omit “but there is not any ADCP data at Absheron Strait” [not relevant to rest of sentence].

Page 24
Lines 9-31. This looks like motivation and should be in the introduction. Discussion here should focus on what is learned from your results.
Line 11. What “reason”? You have not stated one.
Line 12. What “flow”?
Lies 14-15. “However, if . . points. These” -> “Moreover, these”
Line 21. Omit “that”
Line 22. “metres depth of sludge . .”
Line 29. Omit “, although”
Lines 30-31. I think “, as well as . . high latitudes” should be omitted unless you explain how your manuscript contributes to knowledge of risk related to ocean circulation at high latitudes.

Page 25.
Line 2. “the cape” – name it!
Line 4. “its” -> “their”
Line 4. “this result” – what result?
Lines 4-5. “. . concluded . . and surface . .” No: you say nothing about surface flow.
Lines 6-8. I think these sentences are in the wrong place.
Line 6. “4” -> “4.1”.
Line 9. “this problem” – what problem? “problem leads to . . problems” is strange. Do you mean “Climate change leads to many problems in this area . .”?
Lines 17-19. This should be in section 1, last paragraph.

Page 26.
Line 8. This is section 5!
Lines 15-16. This sentence belongs at line 12.

Hide

AR by Anna Mirena Feist-Polner on behalf of the Authors (29 Mar 2019) Author's response

ED: Publish subject to technical corrections (04 Apr 2019) by John M. Huthnance

Dear Authors
Thank-you for your revised manuscript. I am asking for some “Technical Corrections” as below before it goes to the OS/Copernicus production system. Before publication there will be copy editing and you should check that your intended meaning is kept. [I am not involved in that process].
Yours sincerely
John Huthnance

Technical corrections.
Page 2 line 10. Delete “the” at end. [It tends to suggest that all shelves have along-slope currents].

Page 3
Line 7. Better “. . Caspian Sea that has only been touched on in the”?
Line 11. Better “. . overflow. This paper is divided . .”
Line 16. “investigating” -> “of”.

Page 7 line 23. Omit “At the beginning . . pointed out that”

Page 8.
Lines 14-15. Mention of Denmark Strait seems a bit odd here but you refer to it again later. If you want to keep “, similar . . of the DS” then I think you should give a reference here.
Line 17 near end. “on” -> “in”
Line 22. Omit “Over the years”

Page 10 line 19. “. . isopycnal is . .” (space between words)

Page 13.
Line 4. “. . (2003); they used . .”
Line 8. “. . affecting the flow dynamically.”
Line 12. “. . can be shown by numerical model simulation.”
Line 18. “. . behaviour of the vorticity”
Page 14 line 7. Add space between superscript “-1” and “based”.

Page 15 line 15. “. . concentrate on the third layer . .”

Page 16 line 11. “1). Thus rb = . . ); re = . . (transect III) based on”

Page 17.
Line 18. “. . from the cape . .”
Line 20 end. “. . spring (May; Fig. 14).”
Line 31. “in” -> “of” ; “,” after RD should be full size.
Line 32. “. . respectively). Fig. 14 indicates separation . .”
Line 33 & Page 18 line 1. “. . cape, more pronounced in November. Considering . . cape, the Stern criterion . .”

Page 18 line 10. “Absheron” (spelling).

Page 19.
Line 4. “. . basins’ . .”
Line 6. “. . discussed . .”
Line 17. Delete 2nd “Absheron”
Line 21. “. . its geometry and the upper surface of the dense overflow . .”
Line 26. Delete “,” before “(“ and after “)”

Page 20.
Line 13. “1”, “2” should be subscript.
Line 14. Delete “as”
Line 17. “section”
Line 22. “. . which is the approximate . .”
Line 23. “. . basin). Then if . .”

Page 21 lines 12-13. “. . in oceanic contexts without ADCP data, for example the Persian Gulf . . CTD data in the Hormuz”

Page 23.
Line 10. “. . Caspian Sea basins’ flushing times because they are very important . .”
Line 11. Delete “as”
Line 16. “. . that oxygen is carried from . .”
Line 25. “. . sea bed in Absheron . .”
Line 32. “activities at the bottom . .”

Page 24.
Line 1. “. . oil drill holes on Absheron . .”
Line 2. “through” -> “over”
Line 4. Add space before “(“
Line 5. “substantial” -> “significant”? Delete “and climate”? “of” -> “or”
Line 6. Delete “rates”
Lines 6-7. “. . Based on the path of the deep flow and the eddy formation near SefidRud Cape, it can be concluded . .”
Line 10. “. . like sea level . .”
Line 11. Better “. . raised regarding the effect . .”
Line 12. “Based on section 2.1, it is mentioned that the” -> “At present”?
Line 13. Delete “it is accepted that”
Line 15. “. . volume of water in the deep overflow . .”
Line 16. “words, warming probably . .”
Line 22 end. “. . (b) The map” (add space after “)”).

Page 25
Lines 15-16. Better “. . vorticity of the trapped current over Absheron sill.”
Line 17. “. . m3 of water per year in this abyssal flow . .” (add space after superscript 3)
Line 18. “. . which is of the same order . .”

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AR by Javad Babagoli matikolaei on behalf of the Authors (05 Apr 2019) Author's response Manuscript

Short summary

This study investigates the deep gravity current between the middle and southern Caspian Sea basins. Oceanographic data, a numerical model and dynamic models are used to consider the structure of this abyssal overflow. The deep overflow is driven by the density difference – mainly due to the temperature difference between the middle and southern basins – especially in winter. The deep flow may be an important factor influencing oil pollution in the deeper region of the southern Caspian Sea.