the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 24 Mar 2021
Impacts of a large extra-tropical cyclonic system in Southern Brazilian Continental Shelf using the COAWST model
Abstract. The Southern Brazilian Continental Shelf (SBCS) is an area with great ecological and economic importance to Brazil. In this region can be observed the recurrent passage of frontal systems and extra-tropical cyclones, which are more frequent during the winter months of the southern hemisphere. These systems act on the ocean surface layers as direct driving forces, which may change the thermohaline structure of the water column and induce sea level perturbations. This study used the coupled ocean-atmosphere regional model (COAWST) to evaluate the effect of the passage of a frontal system associated with an extra-tropical cyclone. The ROMS oceanic model was configured with two nested grids, in order to solve the hydrodynamic processes at different scales. The parent (20–40° S/40–60° W) and child (25–29.3° S/46.3–50° W) grid comprise the coastal region, with a horizontal resolution of 1/9° and 1/27°, respectively, with 32 vertical levels. The initial conditions are the Global Analysis Forecast from CMEMS and forcing files used the Climate Forecast System v.2 (CFSv2) data, from NCEP. This event took place on the continental shelf of the State of Santa Catarina, in September of 2016. The model results were compared to remote sensing data and to the tide gauges from the City of Imbituba (State of Santa Catarina, Brazil). The comparison showed a correlation higher than 78 % between sea level rise data and the model results. The filtering of sea level data made it possible to identify the meteorological component in the model results. The comparison between the tidal-gauge and the model output presented values under 25 cm. The model was capable of representing the sea level anomalies propagation associated with the passage of the atmospheric frontal system. The model output showed the presence of a sea level anomaly propagating northward along the continental shelf at 480 km day−1, probably associated with the presence of a coastal-trapped wave.
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Interactive discussion
Status: closed
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RC1: 'Comment on os-2021-11', Anonymous Referee #1, 10 Apr 2021
This study uses the COAWST model to study the influence of an atmospheric frontal system to the coastal ocean. The frontal system is associated with an extra-tropical cyclone. The model is based on the ocean circulation model (ROMS) and the weather forecast model WRF using nested grids.
The paper presents some model-data comparison for an event happened in Sep. 2016 and shows the area's sea level anomaly which the authors conclude that it is "probably" due to coastally-trapped waves with a propagation speed of 480 km/day northward.
From what I read, the paper looks like a modeling practice and the results are presented without a clear discussion of the useful dynamics in detail with confidence. In fact, no quantitative analysis to the model output is done. The sea level anomaly should have been analyzed before concluding it is coastally-trapped waves and if the propagation speed matches theory. The figures are of low quality and captions not uniform (some are clear and the others are not).
Some examples of problems, among many others, are
This comparison showed a correlation higher than
Line 28: "78% between sea level rise data and the model results," - sea level rise data? Isn't this a work for a extrotropical cyclone that only lasted for a few days? Why was the short time event related to sea level rise which would be a climate data defined to be 30 years or longer. I guess the authors meant water level data.
Figure 1 is out of the context - it maybe useful for a conference for background but not needed as they have nothing to do with the dynamics and the coastally-trapped waves.
Figure 4, poor quality
Figure 6, Caption is too brief and unclear.
Figure 7, poor quality - but the presentation is odd - I would prefer to see direct comparison between model and data, not separating the tidal and non-tidal parts. If you need to separate them, put the data and model in the same frame and include quantification of statistics (e.g. correlation or R2 value)
Lines 456 and 457: "The physical mechanism that explains the force of the coastal-trapped waves over topography is straightforward,..." then the authors basically referred to some previous papers and finishes their analysis for the coastally-trapped waves. I would not call this paragraph an analysis. The work is not done with quantified analysis and any new finding in dynamics.
Similar problems exist for analysis around Figure 9. Figure 9 is presented in an odd way as well. It is not helpful in providing a clear picture.
For the discussion around Figure 10: why the left panel has no tide while the right panel has tide? What is the reason to not include tide for the along shelf 50-m contour line transect but do include tide for the cross shelf transect?Citation: https://doi.org/10.5194/os-2021-11-RC1 -
AC1: 'Reply on RC1', Luis Felipe Mendonça, 20 Apr 2021
Dear Editor and Anonymous Referee
The authors thank the reviewer #1 for the suggestions regarding the submitted manuscript. All comments were carefully considered by the authors and applied to the manuscript. The following pages show the changes performed. Comments from the reviewers are presented followed by the response from the authors and the changes performed in the manuscript.
Sincerely,
The Authors
Citation: https://doi.org/10.5194/os-2021-11-AC1 -
CC1: 'Reply on RC1', Luis Felipe Mendonça, 20 Apr 2021
Dear Editor and Anonymous Referees
The authors thank the reviewer #1 for the suggestions regarding the submitted manuscript. All comments were carefully considered by the authors and applied to the manuscript. The following pages show the changes performed. Comments from the reviewers are presented followed by the response from the authors and the changes performed in the manuscript.
Sincerely,
The Authors
-
AC1: 'Reply on RC1', Luis Felipe Mendonça, 20 Apr 2021
-
RC2: 'Comment on os-2021-11', Anonymous Referee #2, 23 Apr 2021
This manuscript deals with the impact of an extra-tropical cyclonic system in the Southern Brazilian Continental Shelf using numerical modeling. Although this is an important topic of study, this manuscript presents some problems that do not allow a dynamical understanding of the problem. The main problem of the manuscript is that the numerical simulations present results that do not well represent the observations. For this reasons, mainly, I suggest the rejection of the manuscript. Below, I present in more details the problems that I found:
-Line 69: By shelf waves the authors mean Continental Shelf Waves?
-Line 132: Brazilian Current or Brazil Current?
-Lines 150-153: There are no references regarding the tidal amplitudes.
-Line 159: How near the coast of Brazil?
-Lines 162-163: What do the authors mean by oceanic mesoscale gyration? And why does it cause accumulation of water in the coast?
-Lines 164-166: The authors could give some examples of natural disasters and extreme events in Brazil to put the manuscript in perspective.
-Line 174-175: Models do not provide data.
Lines 180-181: The authors mention the importance of models in understanding coastal processes, but do not mention any of these studies. Also, they should mention the observational studies.
-Line 250 (Data validation): The authors did not validate the data in this section.
-Line 408: The authors present a correlation coefficient (Pearson's) of 0.78, but no significance level. I don't believe this correlation coefficient for SSH low-frequency variability is satisfactory. There are other studies dealing with similar problems that present much higher correlation coefficients for the low-frequency variability (e.g. Costa et al., 2019, Khalid et al. 2020, Ruiz et al. 2021). Why not computing some other statistical parameter that deals with the comparison between actual values and not the variability alone? (e.g. Willmott, 1981)
-Page 15: The figures should present data and model in the same panel.
-Lines 509-511: The authors should present a figure with the locations mentioned in the text, as well as the with of the continental shelf in the domain.
-Line 512: It is hard to see the agreement between data and model. The authors should provide a qualitative method and a better figure.
-Line 516: The delay of few hours is considerably high for these processes. These differences can lead to substantial erros in SSH prediction that do not allow a good understanding of the phenomenom. For instance, if astronomical tides and storm surge peaks are coincident, storm tides can occur. A delay of few hours in one of these process can lead to wrong prediction.
-Lines 552-562: This part of the manuscript looks more like the Introduction.
-Line 566 (Conclusions): For the reasons given above, I believe the conclusions are weakly proved. In essence, the conclusions are very superficial and do not contribute substantially to the knowledge of the process in the region.
Citation: https://doi.org/10.5194/os-2021-11-RC2 -
CC2: 'Reply on RC2', Luis Felipe Mendonça, 30 Apr 2021
Dear Editor and Anonymous Referees
The authors would like to thank reviewer #2 for the suggestions regarding the submitted manuscript. All comments were carefully considered by the authors and applied. His particular corrections were fundamental for the improvement of the manuscript. Reviewer's comments are presented, followed by the response from the authors and the changes performed in the new version of the manuscript.
Sincerely,
The Authors
-
CC2: 'Reply on RC2', Luis Felipe Mendonça, 30 Apr 2021
Interactive discussion
Status: closed
-
RC1: 'Comment on os-2021-11', Anonymous Referee #1, 10 Apr 2021
This study uses the COAWST model to study the influence of an atmospheric frontal system to the coastal ocean. The frontal system is associated with an extra-tropical cyclone. The model is based on the ocean circulation model (ROMS) and the weather forecast model WRF using nested grids.
The paper presents some model-data comparison for an event happened in Sep. 2016 and shows the area's sea level anomaly which the authors conclude that it is "probably" due to coastally-trapped waves with a propagation speed of 480 km/day northward.
From what I read, the paper looks like a modeling practice and the results are presented without a clear discussion of the useful dynamics in detail with confidence. In fact, no quantitative analysis to the model output is done. The sea level anomaly should have been analyzed before concluding it is coastally-trapped waves and if the propagation speed matches theory. The figures are of low quality and captions not uniform (some are clear and the others are not).
Some examples of problems, among many others, are
This comparison showed a correlation higher than
Line 28: "78% between sea level rise data and the model results," - sea level rise data? Isn't this a work for a extrotropical cyclone that only lasted for a few days? Why was the short time event related to sea level rise which would be a climate data defined to be 30 years or longer. I guess the authors meant water level data.
Figure 1 is out of the context - it maybe useful for a conference for background but not needed as they have nothing to do with the dynamics and the coastally-trapped waves.
Figure 4, poor quality
Figure 6, Caption is too brief and unclear.
Figure 7, poor quality - but the presentation is odd - I would prefer to see direct comparison between model and data, not separating the tidal and non-tidal parts. If you need to separate them, put the data and model in the same frame and include quantification of statistics (e.g. correlation or R2 value)
Lines 456 and 457: "The physical mechanism that explains the force of the coastal-trapped waves over topography is straightforward,..." then the authors basically referred to some previous papers and finishes their analysis for the coastally-trapped waves. I would not call this paragraph an analysis. The work is not done with quantified analysis and any new finding in dynamics.
Similar problems exist for analysis around Figure 9. Figure 9 is presented in an odd way as well. It is not helpful in providing a clear picture.
For the discussion around Figure 10: why the left panel has no tide while the right panel has tide? What is the reason to not include tide for the along shelf 50-m contour line transect but do include tide for the cross shelf transect?Citation: https://doi.org/10.5194/os-2021-11-RC1 -
AC1: 'Reply on RC1', Luis Felipe Mendonça, 20 Apr 2021
Dear Editor and Anonymous Referee
The authors thank the reviewer #1 for the suggestions regarding the submitted manuscript. All comments were carefully considered by the authors and applied to the manuscript. The following pages show the changes performed. Comments from the reviewers are presented followed by the response from the authors and the changes performed in the manuscript.
Sincerely,
The Authors
Citation: https://doi.org/10.5194/os-2021-11-AC1 -
CC1: 'Reply on RC1', Luis Felipe Mendonça, 20 Apr 2021
Dear Editor and Anonymous Referees
The authors thank the reviewer #1 for the suggestions regarding the submitted manuscript. All comments were carefully considered by the authors and applied to the manuscript. The following pages show the changes performed. Comments from the reviewers are presented followed by the response from the authors and the changes performed in the manuscript.
Sincerely,
The Authors
-
AC1: 'Reply on RC1', Luis Felipe Mendonça, 20 Apr 2021
-
RC2: 'Comment on os-2021-11', Anonymous Referee #2, 23 Apr 2021
This manuscript deals with the impact of an extra-tropical cyclonic system in the Southern Brazilian Continental Shelf using numerical modeling. Although this is an important topic of study, this manuscript presents some problems that do not allow a dynamical understanding of the problem. The main problem of the manuscript is that the numerical simulations present results that do not well represent the observations. For this reasons, mainly, I suggest the rejection of the manuscript. Below, I present in more details the problems that I found:
-Line 69: By shelf waves the authors mean Continental Shelf Waves?
-Line 132: Brazilian Current or Brazil Current?
-Lines 150-153: There are no references regarding the tidal amplitudes.
-Line 159: How near the coast of Brazil?
-Lines 162-163: What do the authors mean by oceanic mesoscale gyration? And why does it cause accumulation of water in the coast?
-Lines 164-166: The authors could give some examples of natural disasters and extreme events in Brazil to put the manuscript in perspective.
-Line 174-175: Models do not provide data.
Lines 180-181: The authors mention the importance of models in understanding coastal processes, but do not mention any of these studies. Also, they should mention the observational studies.
-Line 250 (Data validation): The authors did not validate the data in this section.
-Line 408: The authors present a correlation coefficient (Pearson's) of 0.78, but no significance level. I don't believe this correlation coefficient for SSH low-frequency variability is satisfactory. There are other studies dealing with similar problems that present much higher correlation coefficients for the low-frequency variability (e.g. Costa et al., 2019, Khalid et al. 2020, Ruiz et al. 2021). Why not computing some other statistical parameter that deals with the comparison between actual values and not the variability alone? (e.g. Willmott, 1981)
-Page 15: The figures should present data and model in the same panel.
-Lines 509-511: The authors should present a figure with the locations mentioned in the text, as well as the with of the continental shelf in the domain.
-Line 512: It is hard to see the agreement between data and model. The authors should provide a qualitative method and a better figure.
-Line 516: The delay of few hours is considerably high for these processes. These differences can lead to substantial erros in SSH prediction that do not allow a good understanding of the phenomenom. For instance, if astronomical tides and storm surge peaks are coincident, storm tides can occur. A delay of few hours in one of these process can lead to wrong prediction.
-Lines 552-562: This part of the manuscript looks more like the Introduction.
-Line 566 (Conclusions): For the reasons given above, I believe the conclusions are weakly proved. In essence, the conclusions are very superficial and do not contribute substantially to the knowledge of the process in the region.
Citation: https://doi.org/10.5194/os-2021-11-RC2 -
CC2: 'Reply on RC2', Luis Felipe Mendonça, 30 Apr 2021
Dear Editor and Anonymous Referees
The authors would like to thank reviewer #2 for the suggestions regarding the submitted manuscript. All comments were carefully considered by the authors and applied. His particular corrections were fundamental for the improvement of the manuscript. Reviewer's comments are presented, followed by the response from the authors and the changes performed in the new version of the manuscript.
Sincerely,
The Authors
-
CC2: 'Reply on RC2', Luis Felipe Mendonça, 30 Apr 2021
Model code and software
set_child_diag.nc / set_child_grd.nc / set_child_his.nc Luís Felipe Mendonça https://1drv.ms/u/s!AhHBb-FlJjz9hY4emL79h33KsB9LCA?e=XVID1p
set_grd.nc / Set_his.nc Luís Felipe Mendonça https://1drv.ms/u/s!AhHBb-FlJjz9hY4emL79h33KsB9LCA?e=XVID1p
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