the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 18 Jul 2022
Numerical Modeling Investigation of Flushing Characteristics and Water Age in a Highly Stratified estuary: Mobile Bay, Alabama, U.S.A.
Abstract. The knowledge of timescales of flushing processes within an estuary is essential for the health, and productivity of the estuary, as well as for optimum estuarine management. The hydrodynamics, flushing times, and freshwater age within Mobile Bay were investigated using a three-dimensional (3D) numerical model, Adaptive Hydraulics. Bay flushing and freshwater times were analyzed for various freshwater flow conditions, wind conditions and investigated the influence of the Coriolis force. The flushing times were directly related to the magnitude of freshwater inputs to the system, with the bay exhibiting an average flushing time of 16.5 days for average river inflows. Freshwater age in the bay was closely associated with the freshwater inflows as well as with location in the Bay and varied from 2 days in the Upper Bay to 21 days in the Lower Bay for average river inflows. Northerly, Easterly, and Westerly winds play an enabling role in the flushing process, with lower depth-averaged flushing times compared to those without winds, with Northerly and Easterly winds being the most efficient. Southerly winds increase flushing times by changing the circulation patterns in the Bay.
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Status: closed
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RC1: 'Comment on egusphere-2022-199', Anonymous Referee #1, 14 Aug 2022
The manuscript focuses on demonstrating the validation of a 3-D numerical hydrodynamical model (Adaptive Hydraulics) that uses an implicit time-stepping method to investigate the flushing characteristics and water age in a highly stratified system (i.e. Mobile Bay).
The manuscript it appears to be surprisingly similar to work that has already been done in this system. It appears to be a near complete re-hash of Du et al. 2018 with nearly the same methods (flushing time and water age, new ocean flux) and a number of figures that look extremely similar. I guess this speaks to the reproducibility of Du et al. (2018) with a different numerical model, which is good. But what is new and novel about this work?
The main findings are basically same as that of Du et al. (i.e. similar methods provided similar results and conclusions) so it feels a bit strange as why this work is so duplicative. It is clear that the authors are aware of Du et al. 2018 as they reference the manuscript several times and even note in the conclusions that "This behavior is consistent with that reported by Du et al. (2018)." There was even overlap in the simulation years. Du et al. simulated 2008.7 to 2010.6 which has a ½ year overlap.
I can understand taking the same methodology and applying it to a different shallow stratified system to see if the findings hold in a general way, but to do the same analysis in the system seems redundant.
The were some difference in the findings but these seemed like minor differences as well as some additional information on various aspects in the system (i.e. impact of Coriolis).
The authors need to clearly highlight that this work largely duplicates the Du et al. (2018) and why such duplication was pursued. I would better highlight how the prime findings are consistent with Du et al. (2018) in a number of places (e.g., importance of baroclinic in flushing time, the relationship be river discharge and flushing time, the circulation maps, etc.) particularly in the introduction, methods, and conclusions. To me, it seems like the authors need clearly credit the finding Du et al. (2018) as their work is duplicative.
I am not sure whether duplicative studies are okay with Ocean Science, if they are than I would recommend publication after major revisions, if not then the manuscript should be rejected. To me this is an editorial descision.
Minor comments
Section 3.1 – Maybe show a plot of the grid mesh? The shoal-channel region of the mesh is a particularly interesting region to get a sense of how the mesh resolved this area.
Section 3.3 Line 232-234 – I believe there may have been persistent salinity measurement during this time period that are publicly available. Looks like several station in the ARCOS network maybe have had continuous salinity data during this time period (https://arcos.disl.org/). Not saying they have to be used, but it is probably not correct to say there are not data.
Figure 13. Caption: Maybe use ‘difference’ rather than ‘stratification’
Figure 15 – The impact of Coriolis looks second order to me. At first glance the water age maps look quite similar. The main differences are in the lower mid-bay region which seems like a pretty subtle change me.
Reference:
Du, J., Park, K., Shen, J., Dzwonkowski, B., Yu, X. and Yoon, B.I., 2018. Role of baroclinic processes on flushing characteristics in a highly stratified estuarine system, Mobile Bay, Alabama. Journal of Geophysical Research: Oceans, 123(7), pp.4518-4537.
Citation: https://doi.org/10.5194/egusphere-2022-199-RC1 -
AC1: 'Reply on RC1', Gaurav Savant, 11 Sep 2022
Dear Reviewer,
Our response is presened in the attached document.
Thank You
-
RC4: 'Reply on AC1', Anonymous Referee #1, 12 Sep 2022
I appreciate the additional information and discussion that the author’s response has provided. However, it was surprising to me that almost no changes in the manuscript were made (as far as I can tell from the response). I am a bit clumsy with the online interactive review system may I missed something.
The author’s do make a case that this work is an incremental contribution and better highlight what is new relative to the work of Du et al. 2018. Yet, they have not incorporated this into the manuscript. As is, the manuscript does not give a sense of the similarity and differences between these works. Again, I feel the authors need to better highlight how the primary findings are consistent with Du et al. (2018) in a number of places (e.g., importance of baroclinic in flushing time, the relationship be river discharge and flushing time, the circulation maps, etc.) as well as some of the differences, particularly in the introduction, methods, discussion and conclusions.
I will say that the differences are very Mobile Bay centric without much generalization. Are there not broader things we can learn from this work? Ideally, the authors could add a paragraph or section about what new general understanding has been found?
I can live with the work staying locally focused, but the author should at least better frame the work in the context with previous work. The original manuscript does reference Du et al. 2018, but they do it way the does not clearly highlight the similarities and differences in the work. Why not include all the points made in the response to reviewer comments with the manuscript? Why not clearly state “provide ample evidence that the science of flushing and other mixing processes in Mobile Bay is unsettled” in the manuscript. Importantly, what might provide clarity? Is vertical resolution the main key? I realize you state this is out of the scope of the work, but to me that is what might make this work interesting to a broader audience.
Authors response on the importance of Coriolis was not particularly effective. But revisiting that section of the manuscript, I think a more compelling argument would be that “The 2.5 day increase in flushing time represents a ~17% increase in flushing time relative to the case without Coriolis.” Again, Figure 15 still does not strike me as significantly different. Only one region of the upper portion of the lower bay is notably different. To me this a second order effect. I am not saying that it is not worth noting, but in my opinion it seems to be second order and should be framed that way.
Note the one minor change to the manscript is very limited. There is times series from Middle Bay Light station a directly adjacent to the ship channel ( https://arcos.disl.org/stations/disl_stations?stationnew=188)
with profiling hydrographic data for years including the study period. I am not saying this data needs to be used and technically the authors revised statement is correct as the station is not in directly in the ship channel, but it makes it seem like that is no data time series data near the ship channel. I guess it is fine since it is technically not incorrect. But the state makes it seem like that is no data available, rather than the authors either being unaware of the data or choosing not to use it. Maybe it is better to just remove the statement or at least remove the salinity part.
Since almost no changes to the manuscript have been made. I am generally left with the similar comments that I provided in the first reviewer comments. Overall, if Ocean Science is okay with local focused studies, then I would recommend publication after revisions (to me having the context of what Du et al. 2018 did is important to this work given the similarity in methodology and results), if not then the manuscript should be rejected (or further change regarding broader finding is needed). To me this is an editorial decision.
Citation: https://doi.org/10.5194/egusphere-2022-199-RC4 -
AC4: 'Reply on RC4', Gaurav Savant, 12 Sep 2022
Hi,
Good Morning! We have been trying to upload a new manuscript, but are unsure of where to do it. It should be updated as soon as we figure out how to.
Thanks
Citation: https://doi.org/10.5194/egusphere-2022-199-AC4 -
RC5: 'Reply on AC4', Anonymous Referee #1, 12 Sep 2022
I understand. Just let me know when the revised manuscript shows up.
Citation: https://doi.org/10.5194/egusphere-2022-199-RC5 -
AC5: 'Reply on RC5', Gaurav Savant, 12 Sep 2022
Belois what we got from editorial support. Therefore, I'll upload the commented manuscript in the comments to you. I'll lleave track changes on, so the changes are visible.
"
Dear Gaurav Savant
I see from the discussion that you have trouble uploading a revised manuscript. I think this may be because the discussion period is still in progress. When the discussion is closed and you have responded to referee comments (as you have so far) then the editorial system should tell you what to do. [To me there is some sense in only having one version of the manuscript under discussion - to avoid confusion.]
Yours sincerely
John Huthnance (editor)
"
Citation: https://doi.org/10.5194/egusphere-2022-199-AC5 -
RC6: 'Reply on AC5', Anonymous Referee #1, 13 Sep 2022
Thanks for the update. I guessing most of my comments may not reflect the latest version of the manuscript. Once a new version can be uploaded, just let me know or hopefully the journal will notify the reviewers.
Citation: https://doi.org/10.5194/egusphere-2022-199-RC6 -
AC6: 'Reply on RC6', Gaurav Savant, 18 Sep 2022
The journal should be uploading a manuscript anyday now.
Citation: https://doi.org/10.5194/egusphere-2022-199-AC6
-
AC6: 'Reply on RC6', Gaurav Savant, 18 Sep 2022
-
RC6: 'Reply on AC5', Anonymous Referee #1, 13 Sep 2022
-
AC5: 'Reply on RC5', Gaurav Savant, 12 Sep 2022
-
RC5: 'Reply on AC4', Anonymous Referee #1, 12 Sep 2022
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AC4: 'Reply on RC4', Gaurav Savant, 12 Sep 2022
-
RC4: 'Reply on AC1', Anonymous Referee #1, 12 Sep 2022
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AC1: 'Reply on RC1', Gaurav Savant, 11 Sep 2022
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RC2: 'Comment on egusphere-2022-199', Anonymous Referee #2, 15 Aug 2022
I can only concur with the comments of Referee #1 in that the similartities of the pressent submission with the previous article of Du et al. (JGR, 2018) must led one to wonder what is really novel here -- in terms of methodology, flow diagnoses and conclusions. The Authors should be given a chance to rebut all this in detail, thereby explaining why their study should be published -- and why that of Du et al. (2018) is no longer sufficient.
Citation: https://doi.org/10.5194/egusphere-2022-199-RC2 - AC2: 'Reply on RC2', Gaurav Savant, 11 Sep 2022
-
RC3: 'Comment on egusphere-2022-199', Anonymous Referee #3, 17 Aug 2022
This manuscript describes a numerical model study of the water renewal in Mobile Bay, Alabama, USA. The model is validated against in situ measurements of water levels and salinity. The model performs very well. The authors use well-established methods to quantify water renewal processes in the bay. The problem is that the hydrodynamics of Mobile Bay is already well documented in the literature, including its water renewal processes (e.g., Du et al., 2018, JGR Oceans). It is unclear what this study brings to existing knowledge.
In particular, the authors use the concepts of flushing time and water age to analyze the water renewal in Mobile Bay under different river flow conditions and wind directions, which is exactly what is done by Du et al. (2018) and the conclusions are very similar. Only the impact of the Coriolis force is new in this study, but Figure 15 indicates that this impact is very low, unlike what the authors claim in the text.
As both the methodology and the scientific questions addressed in this manuscript are not novel, its scientific relevance is rather low. Besides, the broader relevance of the results to better understand other stratified estuaries globally is not discussed. Therefore, I would not recommend the publication of this manuscript in Ocean Sciences.
Citation: https://doi.org/10.5194/egusphere-2022-199-RC3 - AC3: 'Reply on RC3', Gaurav Savant, 11 Sep 2022
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EC1: 'Comment on egusphere-2022-199', John M. Huthnance, 19 Sep 2022
Dear Authors
You have seen and respnded to the reviewers comments. However, you should incorporate enough of your response in the revised manuscript to make it self-contained; it should explain how your work differs from and advances on previous studies. Please do not rely on the discussion for that.
Yours sincerely
John Huthnance (editor)
Citation: https://doi.org/10.5194/egusphere-2022-199-EC1 -
AC7: 'Reply on EC1', Gaurav Savant, 19 Sep 2022
John,
Good Morning! We have added to the conclusions section details on how we differ, and possible reasons for the differences. we also mentioned in the introduction the differences between our work and the works of Du et al. (2018).
Citation: https://doi.org/10.5194/egusphere-2022-199-AC7
-
AC7: 'Reply on EC1', Gaurav Savant, 19 Sep 2022
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2022-199', Anonymous Referee #1, 14 Aug 2022
The manuscript focuses on demonstrating the validation of a 3-D numerical hydrodynamical model (Adaptive Hydraulics) that uses an implicit time-stepping method to investigate the flushing characteristics and water age in a highly stratified system (i.e. Mobile Bay).
The manuscript it appears to be surprisingly similar to work that has already been done in this system. It appears to be a near complete re-hash of Du et al. 2018 with nearly the same methods (flushing time and water age, new ocean flux) and a number of figures that look extremely similar. I guess this speaks to the reproducibility of Du et al. (2018) with a different numerical model, which is good. But what is new and novel about this work?
The main findings are basically same as that of Du et al. (i.e. similar methods provided similar results and conclusions) so it feels a bit strange as why this work is so duplicative. It is clear that the authors are aware of Du et al. 2018 as they reference the manuscript several times and even note in the conclusions that "This behavior is consistent with that reported by Du et al. (2018)." There was even overlap in the simulation years. Du et al. simulated 2008.7 to 2010.6 which has a ½ year overlap.
I can understand taking the same methodology and applying it to a different shallow stratified system to see if the findings hold in a general way, but to do the same analysis in the system seems redundant.
The were some difference in the findings but these seemed like minor differences as well as some additional information on various aspects in the system (i.e. impact of Coriolis).
The authors need to clearly highlight that this work largely duplicates the Du et al. (2018) and why such duplication was pursued. I would better highlight how the prime findings are consistent with Du et al. (2018) in a number of places (e.g., importance of baroclinic in flushing time, the relationship be river discharge and flushing time, the circulation maps, etc.) particularly in the introduction, methods, and conclusions. To me, it seems like the authors need clearly credit the finding Du et al. (2018) as their work is duplicative.
I am not sure whether duplicative studies are okay with Ocean Science, if they are than I would recommend publication after major revisions, if not then the manuscript should be rejected. To me this is an editorial descision.
Minor comments
Section 3.1 – Maybe show a plot of the grid mesh? The shoal-channel region of the mesh is a particularly interesting region to get a sense of how the mesh resolved this area.
Section 3.3 Line 232-234 – I believe there may have been persistent salinity measurement during this time period that are publicly available. Looks like several station in the ARCOS network maybe have had continuous salinity data during this time period (https://arcos.disl.org/). Not saying they have to be used, but it is probably not correct to say there are not data.
Figure 13. Caption: Maybe use ‘difference’ rather than ‘stratification’
Figure 15 – The impact of Coriolis looks second order to me. At first glance the water age maps look quite similar. The main differences are in the lower mid-bay region which seems like a pretty subtle change me.
Reference:
Du, J., Park, K., Shen, J., Dzwonkowski, B., Yu, X. and Yoon, B.I., 2018. Role of baroclinic processes on flushing characteristics in a highly stratified estuarine system, Mobile Bay, Alabama. Journal of Geophysical Research: Oceans, 123(7), pp.4518-4537.
Citation: https://doi.org/10.5194/egusphere-2022-199-RC1 -
AC1: 'Reply on RC1', Gaurav Savant, 11 Sep 2022
Dear Reviewer,
Our response is presened in the attached document.
Thank You
-
RC4: 'Reply on AC1', Anonymous Referee #1, 12 Sep 2022
I appreciate the additional information and discussion that the author’s response has provided. However, it was surprising to me that almost no changes in the manuscript were made (as far as I can tell from the response). I am a bit clumsy with the online interactive review system may I missed something.
The author’s do make a case that this work is an incremental contribution and better highlight what is new relative to the work of Du et al. 2018. Yet, they have not incorporated this into the manuscript. As is, the manuscript does not give a sense of the similarity and differences between these works. Again, I feel the authors need to better highlight how the primary findings are consistent with Du et al. (2018) in a number of places (e.g., importance of baroclinic in flushing time, the relationship be river discharge and flushing time, the circulation maps, etc.) as well as some of the differences, particularly in the introduction, methods, discussion and conclusions.
I will say that the differences are very Mobile Bay centric without much generalization. Are there not broader things we can learn from this work? Ideally, the authors could add a paragraph or section about what new general understanding has been found?
I can live with the work staying locally focused, but the author should at least better frame the work in the context with previous work. The original manuscript does reference Du et al. 2018, but they do it way the does not clearly highlight the similarities and differences in the work. Why not include all the points made in the response to reviewer comments with the manuscript? Why not clearly state “provide ample evidence that the science of flushing and other mixing processes in Mobile Bay is unsettled” in the manuscript. Importantly, what might provide clarity? Is vertical resolution the main key? I realize you state this is out of the scope of the work, but to me that is what might make this work interesting to a broader audience.
Authors response on the importance of Coriolis was not particularly effective. But revisiting that section of the manuscript, I think a more compelling argument would be that “The 2.5 day increase in flushing time represents a ~17% increase in flushing time relative to the case without Coriolis.” Again, Figure 15 still does not strike me as significantly different. Only one region of the upper portion of the lower bay is notably different. To me this a second order effect. I am not saying that it is not worth noting, but in my opinion it seems to be second order and should be framed that way.
Note the one minor change to the manscript is very limited. There is times series from Middle Bay Light station a directly adjacent to the ship channel ( https://arcos.disl.org/stations/disl_stations?stationnew=188)
with profiling hydrographic data for years including the study period. I am not saying this data needs to be used and technically the authors revised statement is correct as the station is not in directly in the ship channel, but it makes it seem like that is no data time series data near the ship channel. I guess it is fine since it is technically not incorrect. But the state makes it seem like that is no data available, rather than the authors either being unaware of the data or choosing not to use it. Maybe it is better to just remove the statement or at least remove the salinity part.
Since almost no changes to the manuscript have been made. I am generally left with the similar comments that I provided in the first reviewer comments. Overall, if Ocean Science is okay with local focused studies, then I would recommend publication after revisions (to me having the context of what Du et al. 2018 did is important to this work given the similarity in methodology and results), if not then the manuscript should be rejected (or further change regarding broader finding is needed). To me this is an editorial decision.
Citation: https://doi.org/10.5194/egusphere-2022-199-RC4 -
AC4: 'Reply on RC4', Gaurav Savant, 12 Sep 2022
Hi,
Good Morning! We have been trying to upload a new manuscript, but are unsure of where to do it. It should be updated as soon as we figure out how to.
Thanks
Citation: https://doi.org/10.5194/egusphere-2022-199-AC4 -
RC5: 'Reply on AC4', Anonymous Referee #1, 12 Sep 2022
I understand. Just let me know when the revised manuscript shows up.
Citation: https://doi.org/10.5194/egusphere-2022-199-RC5 -
AC5: 'Reply on RC5', Gaurav Savant, 12 Sep 2022
Belois what we got from editorial support. Therefore, I'll upload the commented manuscript in the comments to you. I'll lleave track changes on, so the changes are visible.
"
Dear Gaurav Savant
I see from the discussion that you have trouble uploading a revised manuscript. I think this may be because the discussion period is still in progress. When the discussion is closed and you have responded to referee comments (as you have so far) then the editorial system should tell you what to do. [To me there is some sense in only having one version of the manuscript under discussion - to avoid confusion.]
Yours sincerely
John Huthnance (editor)
"
Citation: https://doi.org/10.5194/egusphere-2022-199-AC5 -
RC6: 'Reply on AC5', Anonymous Referee #1, 13 Sep 2022
Thanks for the update. I guessing most of my comments may not reflect the latest version of the manuscript. Once a new version can be uploaded, just let me know or hopefully the journal will notify the reviewers.
Citation: https://doi.org/10.5194/egusphere-2022-199-RC6 -
AC6: 'Reply on RC6', Gaurav Savant, 18 Sep 2022
The journal should be uploading a manuscript anyday now.
Citation: https://doi.org/10.5194/egusphere-2022-199-AC6
-
AC6: 'Reply on RC6', Gaurav Savant, 18 Sep 2022
-
RC6: 'Reply on AC5', Anonymous Referee #1, 13 Sep 2022
-
AC5: 'Reply on RC5', Gaurav Savant, 12 Sep 2022
-
RC5: 'Reply on AC4', Anonymous Referee #1, 12 Sep 2022
-
AC4: 'Reply on RC4', Gaurav Savant, 12 Sep 2022
-
RC4: 'Reply on AC1', Anonymous Referee #1, 12 Sep 2022
-
AC1: 'Reply on RC1', Gaurav Savant, 11 Sep 2022
-
RC2: 'Comment on egusphere-2022-199', Anonymous Referee #2, 15 Aug 2022
I can only concur with the comments of Referee #1 in that the similartities of the pressent submission with the previous article of Du et al. (JGR, 2018) must led one to wonder what is really novel here -- in terms of methodology, flow diagnoses and conclusions. The Authors should be given a chance to rebut all this in detail, thereby explaining why their study should be published -- and why that of Du et al. (2018) is no longer sufficient.
Citation: https://doi.org/10.5194/egusphere-2022-199-RC2 - AC2: 'Reply on RC2', Gaurav Savant, 11 Sep 2022
-
RC3: 'Comment on egusphere-2022-199', Anonymous Referee #3, 17 Aug 2022
This manuscript describes a numerical model study of the water renewal in Mobile Bay, Alabama, USA. The model is validated against in situ measurements of water levels and salinity. The model performs very well. The authors use well-established methods to quantify water renewal processes in the bay. The problem is that the hydrodynamics of Mobile Bay is already well documented in the literature, including its water renewal processes (e.g., Du et al., 2018, JGR Oceans). It is unclear what this study brings to existing knowledge.
In particular, the authors use the concepts of flushing time and water age to analyze the water renewal in Mobile Bay under different river flow conditions and wind directions, which is exactly what is done by Du et al. (2018) and the conclusions are very similar. Only the impact of the Coriolis force is new in this study, but Figure 15 indicates that this impact is very low, unlike what the authors claim in the text.
As both the methodology and the scientific questions addressed in this manuscript are not novel, its scientific relevance is rather low. Besides, the broader relevance of the results to better understand other stratified estuaries globally is not discussed. Therefore, I would not recommend the publication of this manuscript in Ocean Sciences.
Citation: https://doi.org/10.5194/egusphere-2022-199-RC3 - AC3: 'Reply on RC3', Gaurav Savant, 11 Sep 2022
-
EC1: 'Comment on egusphere-2022-199', John M. Huthnance, 19 Sep 2022
Dear Authors
You have seen and respnded to the reviewers comments. However, you should incorporate enough of your response in the revised manuscript to make it self-contained; it should explain how your work differs from and advances on previous studies. Please do not rely on the discussion for that.
Yours sincerely
John Huthnance (editor)
Citation: https://doi.org/10.5194/egusphere-2022-199-EC1 -
AC7: 'Reply on EC1', Gaurav Savant, 19 Sep 2022
John,
Good Morning! We have added to the conclusions section details on how we differ, and possible reasons for the differences. we also mentioned in the introduction the differences between our work and the works of Du et al. (2018).
Citation: https://doi.org/10.5194/egusphere-2022-199-AC7
-
AC7: 'Reply on EC1', Gaurav Savant, 19 Sep 2022
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