the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 10 Mar 2023
Intense Anticyclones at the Global Argentine Basin Array of the Ocean Observatory Initiative
Abstract. We analyzed physical oceanic parameters gathered by a mooring array at mesoscale spatial sampling deployed in Argentine Basin within the Ocean Observatory Initiative, a National Science Foundation Major Research Facility. The array was maintained at 42° S 42° W, a historically sparsely sampled region with small ocean variability, during 34 months from March 2015 to January 2018. The data documented four anticyclonic extreme structures events in 2016. The four anticyclonic structures had different characteristics (size, vertical extension, origin, lifetime, Rossby Number). They all featured near-inertial waves (NIWs) trapped at depth and low Richardson values well below the mixed layer. Low Richardson values suggest favorable conditions for mixing. The anticyclonic features likely act as mixing structures at the pycnocline bringing heat and salt from the South Atlantic Central Water to the Antarctic Intermediate Waters. The intense structures were unique in the 29-year-long satellite altimetry record at the mooring site. The Argentine Basin is populated with many anticyclones and mixing associated to trapped NIWs probably plays an important role in setting up the upper water masses characteristics in the Basin.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
(13362 KB)
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
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- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2023-424', Anonymous Referee #1, 26 Apr 2023
Summary and recommenndation: The authors analysed multi-year observations from a mooring array deployed in the Argentine Basin, and focued on a few intense anticyclonic eddy events during when near-inertial waves were also excited and mixing was likely to occur. The manuscript is overall clear and well written, and in my opinion, only minor revisions are needed so that the manuscript may be considered for publication.
General comments:
Figure 3: It seems that there are other extreme events occurred around 04/15, 12/16, 03/17, 04/17. Are these also events of mesoscale structures? Could you add some descriptions these events as well?
Figure 6: A large fraction of mesoscale signals would be filtered out when you used the a low-pass window of 180 days. Why don’t you use a shorter temporal window like 30 days? Also, is there a mean flow in this region?
Figure 7: It would be interesting to superimpose on the Figure 7(a-c) the isopycnals obtained from the moorings to better show the passage of the eddy.
Line 224: Is there any direct evidence to show the NIW event was generated by local winds? I cannot find it in the paper. What is the tau signal during each event? It would be good to give estimates of wind energy into NIW, and also try a slab model to demonstrate the wind-driven NIWs.
Figure 11: It’s really hard to see the downward energy propagation of NIWs from the figure? The vertical propagation of NIWs may be estimated directly by fitting a curve to the near-inertial KE maxima (it could also be obtained by fitting the curve to the averaged near-inertial KE values above a threshold value. Tests should be carried out to decide which method is the best).
Citation: https://doi.org/10.5194/egusphere-2023-424-RC1 - AC1: 'Reply on RC1', Camila Artana, 05 May 2023
- AC2: 'Reply on RC1', Camila Artana, 22 May 2023
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RC2: 'Comment on egusphere-2023-424', Anonymous Referee #2, 17 May 2023
In this study, the researchers examined data from a mooring array deployed in the Argentine Basin over several years. They specifically investigated intense anticyclonic eddy events accompanied by the excitation of near-inertial waves and the likelihood of mixing.
The paper demonstrates good writing quality, but there are a few aspects and minor reviews that the authors should revisit to improve the manuscript and be published.
Line 12: The citation (Artana et al., 2021) appears to be inappropriate. There exist classical papers demonstrating the intricacy of water masses in this particular region.
Lines 15 and 16: Citations concerning the hydrodynamics of the Brazil Current are absent in this context.
Line 57: What is the bin size of the ADCP? It is essential to provide this information explicitly as you are calculating vertical shear using these measurements.
Line 63-65: This sentence might be improved. Please, revisit the cited paper and provide more details about the data processing.
Line 67-68: “Data quality … close to the surface” Same as the comment above. How did you quantify the data quality?
Fig03: While I concur with the authors' observation that the periods of A0, A1, and A2 could be associated with mesoscale features, it is worth noting the presence of numerous similar signals. Do these signals also have a connection to mesoscale eddies? A discussion exploring this aspect would enhance our comprehension of these figures.
Line 118: “… significant trend..” Has a statistical time-series analysis been conducted, or is there a citation supporting this statement? If not, it is advisable to refrain from using the term "significant," as it implies a requirement for a statistical approach.
Line 160: “..was originated from the Brazil Current” » propagated from the Brazil Current domain
Line 164: As the analysis does not encompass the investigation of the generation mechanism of these eddies, it is advisable to avoid using the term "generation."
Fig10: I apologize for any oversight in the manuscript. Please review the document to ensure that the definitions of CW and CCW are provided.
Line 218: significant > proeminent ???
Line 220: The authors mentioned the possibility of local wind as a driving force for the generation of NIWs. However, I am unclear about the basis for this speculation. While it is true that NIWs are predominantly influenced by wind, I recommend conducting additional analysis to support this claim. One potential approach could involve utilizing a simple mixed-layer slab model, which would greatly enhance the final version of the paper.
Lines 228-230: It seems that you are referring to the zeta-refraction mechanism. In light of this, a discussion about this process is warranted to further elaborate on its role and significance.
Figure 11: It would be more advantageous to represent the x-axis as an inertial period rather than using real dates. This adjustment may provide better clarity on the behavior of NIWs.
Line 246 and Figure 12c: Positive values of \zeta/f in the Southern Hemisphere should be negative. Please check if you are computing properly.
Item 4.3: Is the vertical scale of measurements (dz) sufficient to suggest that vertical shear can potentially overcome stratification and destabilize the flow? A comprehensive discussion on this topic would enhance the manuscript. Additionally, it is mentioned that the authors obtained values of Ri close to a quarter using a coarse spatial resolution by calculating the minimum ratio between N^2 and S^2. Could you provide insight into the data distribution? Is the minimum ratio a representative measure of Ri? I recommend comparing it with a bulk estimation of Ri and assessing whether using the minimum Ri value adequately captures the overall representation.
Label of section 5: Conclusions> Summary and conclusions
Line 300: Rossby baroclinic deformation radius. Please provide the actual value.
Line 306: birthplace??? Could you really access the origin of such an eddy?
Line 318-319: The sentence in question appears to be overly speculative. Please rephrase it.
Citation: https://doi.org/10.5194/egusphere-2023-424-RC2 - AC3: 'Reply on RC2', Camila Artana, 22 May 2023
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EC1: 'Comment on egusphere-2023-424', Karen J. Heywood, 22 May 2023
You have two helpful and positive reviews. I am sure that these will help to further strengthen your paper and look forward to receiving your revision and final responses.
Citation: https://doi.org/10.5194/egusphere-2023-424-EC1
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2023-424', Anonymous Referee #1, 26 Apr 2023
Summary and recommenndation: The authors analysed multi-year observations from a mooring array deployed in the Argentine Basin, and focued on a few intense anticyclonic eddy events during when near-inertial waves were also excited and mixing was likely to occur. The manuscript is overall clear and well written, and in my opinion, only minor revisions are needed so that the manuscript may be considered for publication.
General comments:
Figure 3: It seems that there are other extreme events occurred around 04/15, 12/16, 03/17, 04/17. Are these also events of mesoscale structures? Could you add some descriptions these events as well?
Figure 6: A large fraction of mesoscale signals would be filtered out when you used the a low-pass window of 180 days. Why don’t you use a shorter temporal window like 30 days? Also, is there a mean flow in this region?
Figure 7: It would be interesting to superimpose on the Figure 7(a-c) the isopycnals obtained from the moorings to better show the passage of the eddy.
Line 224: Is there any direct evidence to show the NIW event was generated by local winds? I cannot find it in the paper. What is the tau signal during each event? It would be good to give estimates of wind energy into NIW, and also try a slab model to demonstrate the wind-driven NIWs.
Figure 11: It’s really hard to see the downward energy propagation of NIWs from the figure? The vertical propagation of NIWs may be estimated directly by fitting a curve to the near-inertial KE maxima (it could also be obtained by fitting the curve to the averaged near-inertial KE values above a threshold value. Tests should be carried out to decide which method is the best).
Citation: https://doi.org/10.5194/egusphere-2023-424-RC1 - AC1: 'Reply on RC1', Camila Artana, 05 May 2023
- AC2: 'Reply on RC1', Camila Artana, 22 May 2023
-
RC2: 'Comment on egusphere-2023-424', Anonymous Referee #2, 17 May 2023
In this study, the researchers examined data from a mooring array deployed in the Argentine Basin over several years. They specifically investigated intense anticyclonic eddy events accompanied by the excitation of near-inertial waves and the likelihood of mixing.
The paper demonstrates good writing quality, but there are a few aspects and minor reviews that the authors should revisit to improve the manuscript and be published.
Line 12: The citation (Artana et al., 2021) appears to be inappropriate. There exist classical papers demonstrating the intricacy of water masses in this particular region.
Lines 15 and 16: Citations concerning the hydrodynamics of the Brazil Current are absent in this context.
Line 57: What is the bin size of the ADCP? It is essential to provide this information explicitly as you are calculating vertical shear using these measurements.
Line 63-65: This sentence might be improved. Please, revisit the cited paper and provide more details about the data processing.
Line 67-68: “Data quality … close to the surface” Same as the comment above. How did you quantify the data quality?
Fig03: While I concur with the authors' observation that the periods of A0, A1, and A2 could be associated with mesoscale features, it is worth noting the presence of numerous similar signals. Do these signals also have a connection to mesoscale eddies? A discussion exploring this aspect would enhance our comprehension of these figures.
Line 118: “… significant trend..” Has a statistical time-series analysis been conducted, or is there a citation supporting this statement? If not, it is advisable to refrain from using the term "significant," as it implies a requirement for a statistical approach.
Line 160: “..was originated from the Brazil Current” » propagated from the Brazil Current domain
Line 164: As the analysis does not encompass the investigation of the generation mechanism of these eddies, it is advisable to avoid using the term "generation."
Fig10: I apologize for any oversight in the manuscript. Please review the document to ensure that the definitions of CW and CCW are provided.
Line 218: significant > proeminent ???
Line 220: The authors mentioned the possibility of local wind as a driving force for the generation of NIWs. However, I am unclear about the basis for this speculation. While it is true that NIWs are predominantly influenced by wind, I recommend conducting additional analysis to support this claim. One potential approach could involve utilizing a simple mixed-layer slab model, which would greatly enhance the final version of the paper.
Lines 228-230: It seems that you are referring to the zeta-refraction mechanism. In light of this, a discussion about this process is warranted to further elaborate on its role and significance.
Figure 11: It would be more advantageous to represent the x-axis as an inertial period rather than using real dates. This adjustment may provide better clarity on the behavior of NIWs.
Line 246 and Figure 12c: Positive values of \zeta/f in the Southern Hemisphere should be negative. Please check if you are computing properly.
Item 4.3: Is the vertical scale of measurements (dz) sufficient to suggest that vertical shear can potentially overcome stratification and destabilize the flow? A comprehensive discussion on this topic would enhance the manuscript. Additionally, it is mentioned that the authors obtained values of Ri close to a quarter using a coarse spatial resolution by calculating the minimum ratio between N^2 and S^2. Could you provide insight into the data distribution? Is the minimum ratio a representative measure of Ri? I recommend comparing it with a bulk estimation of Ri and assessing whether using the minimum Ri value adequately captures the overall representation.
Label of section 5: Conclusions> Summary and conclusions
Line 300: Rossby baroclinic deformation radius. Please provide the actual value.
Line 306: birthplace??? Could you really access the origin of such an eddy?
Line 318-319: The sentence in question appears to be overly speculative. Please rephrase it.
Citation: https://doi.org/10.5194/egusphere-2023-424-RC2 - AC3: 'Reply on RC2', Camila Artana, 22 May 2023
-
EC1: 'Comment on egusphere-2023-424', Karen J. Heywood, 22 May 2023
You have two helpful and positive reviews. I am sure that these will help to further strengthen your paper and look forward to receiving your revision and final responses.
Citation: https://doi.org/10.5194/egusphere-2023-424-EC1
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Cited
Camila Artana
Christine Provost
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(13362 KB) - Metadata XML