the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 04 Aug 2023
The Different Dynamic Influences of Typhoon Kalmaegi on two Pre-existing Anticyclonic Ocean Eddy
Abstract. Using multi-source observational data and GLORYS12V1 reanalysis data, we conducted a comparative analysis of different responses of two warm eddies, AE1 and AE2 in the northern South China Sea to Typhoon Kalmaegi during September 2014. The findings of our research are as follows: (1) For horizontal distribution, the area and the sea surface temperature (SST) of AE1 and AE2 decreased by about 31 % (36 %) and 0.4 °C (0.6 °C).The amplitude, Rossby number (Ro) and eddy kinetic energy (EKE) of AE1 increased by 1.3 cm, 1.4×10-2 and 107.2 cm2 s-2 after the typhoon, respectively, while AE2 weakened and the amplitude, vorticity and EKE decreased by 3.1 cm, 1.6×10-2 and 38.5 cm2 s-2, respectively. (2) In vertical direction, AE1 demonstrated enhanced convergence, leading to an increase in temperature and a decrease in salinity above 150 m. The response below the mixing layer depth (MLD) was particularly prominent (1.3 °C). In contrast, AE2 experienced cooling and a decrease in salinity above the MLD. Below the MLD, it exhibited a subsurface temperature drop and salinity increase due to the upwelling of cold water induced by the suction effect of the typhoon. (3) The disparity in the responses of the two warm eddies can be attributed to their different positions relative to Typhoon Kalmaegi. Warm eddy AE1, with its center located on the left side of the typhoon's path, experienced a positive work effect as the typhoon passed by. This induced a strong negative wind stress curl and triggered a negative Ekman pumping velocity (EPV), further enhanced by the converging sinking of the upper warm water, thereby strengthening AE1. On the other hand, warm eddy AE2, situated closer to the center of the typhoon, weakened due to the cold suction caused by the strong positive wind stress curl in the typhoon's center. These findings underscore the importance of relative positions of eddies in their interactions with typhoons.
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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.
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Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2023-1734', Anonymous Referee #1, 24 Aug 2023
I don’t think this paper is publishable; so sorry.
General Comments: Kalmaegi was a fast-moving TC. At 8 m/s, the TC traverses ~600 km in 1 day and spent ~6 hours traversing AE1 (or AE2) with a diameter of about 150 km. In such a super-critically moving storm, most of the wind effect on the ocean is therefore through mixing (including perhaps that caused by near-inertial internal wave breaking in the upper ocean in the wake of the storm) rather than the wind stress curl. The latter would require that wind acts on the ocean in a time scale longer than the inertial period (~1.5 days at 19N). I understand the authors' hypothesis of the negative WSC (thus convergence) on the left side, etc., but I don't think it is a demonstrable one in this case and is most likely incorrect. The increased AE1 after Kalmaegi (Fig.3, etc.) is likely a complex eddy adjustment process. One may suspect such adjustment also from Fig.3 in which the "warm" area between AE1 and AE2, including that on the left side, shrinks or weakens. That area would have expanded following the authors' hypothesis.
Two other general comments. 1) AE1’s increased amplitude, Ro and EKE = 1.3 cm, 1.4e-2 and 107 (cm/s)^2 are small. Are they statistically significant, and were errors and confidence levels estimated? Similarly for AE2. 2) Inertial oscillatory response persists long (~5 days and longer) after a storm passes (see e.g. Wu et al. Effect of Typhoon Kalmaegi (2014) on northern South China Sea explored using Muti-platform satellite and buoy observations data; Prog Oceanogr. 180 (2020) 102218). The effects of inertial motions on the Authors’ results and analyses were not discussed and I am unsure, for example, how the effects were filtered out or accounted for and how they may affect their estimates.
Other Comments:
L14: Rossby number (Ro = relative vorticity/Coriolis parameter);
L16: Rossby number;
L166: vertical feedback of the ocean by ... Kalmaegi: Not sure what this means, what "feedback", maybe "response..."?
Also: I assume GLORY assimilates Argo data but not the Station data. If so, then it is unsurprising that GLORY agrees with ARGO but not Station 5 (Figure 1).
Only Station 5 on the left side of the storm was used to support the authors' hypothesis. To support (refute?) the Authors' hypothesis I suggest using data from other Stations (except #3), right and left of Kalmaegi.
L223: ... weak wind stress curl, to be more precise. The term "wind shear" is also customarily taken as "vertical wind shear" in TC studies in meteorology so can be confusing.
L245: ... with 6-hourly dots.
.
.
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AC1: 'Reply on RC1', Xiayan Lin, 30 Oct 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1734/egusphere-2023-1734-AC1-supplement.pdf
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AC1: 'Reply on RC1', Xiayan Lin, 30 Oct 2023
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RC2: 'Comment on egusphere-2023-1734', Anonymous Referee #2, 08 Sep 2023
General comments:
The authors investigated the responses of two warm eddies to a typhoon using observational and reanalysis data. There have been lots of efforts on eddy feedback to TC evolution, while our understanding of eddy response to TCs remains limited. The work is potentially interesting and contribute to broaden the knowledge of TC-eddy interaction, but I have some comments before the paper can be published. I recommend moderate to minor revision of the manuscript.
Primary comments:
- The motivation of conducting the study should be more clarified. Just stating that “However, there has been relatively limited exploration of different responses exhibited by warm eddies under the influence of typhoons” is not adequate from my opinion. There have been several studies on the eddy response to TCs. The authors should be more carefully summarize what have been reported from these previous studies, and what new knowledge will be reported in this study.
- The writing of the paper needs a substantial improvement. There are lots of sentences that are hard to follow and hinder understanding. The logics between paragraphs should be clear. On Line 31, the word of “typhoon” is used, but in the following the “tropical cyclone” is used instead. The paper should keep consistency in word usage.
Specific comments:
1. Is it reasonable to use the rectangle areas represent AE1 and AE2 (Figure 1)? As eddies always move during typhoon.
2. There are several common issues with the figures in the manuscript that need to be addressed, including the addition of x-labels and y-labels, as well as the unification of font sizes etc. Specific comments are as follows:
1). Figure 1: The first letter of “depth” in Y-label needs to be capitalized.
2). Figure 4: Just keep one arrow legend and text of ”15 m/s” in (a), the quiver and the text should be larger.
3). The coordinate axes are duplicated in Figure 5, delete the x-axis and y-axis in Figure 5 (a), (d), (g), (j), just like Figure 4; Set the range of SST colorbar as 26 to 31 °C; Change the red dots to larger black dots.
4). Figure 6: The first letter of “date” needs to be capitalized, like “Date”.
5). Figure 7: The first letter of “date” and “depth” needs to be capitalized; The unit of “psu” should be “PSU”.
6). Figure 8: The first letter of “date” and “depth” needs to be capitalized; Please use the density excess replace the density, that means density minus 1000 kg. m-3; The unit of buoyancy should be written as “N2 (10-4 s-2)”.
7). Figure 9: The first letter of “depth” needs to be capitalized; “psu” should be “PSU”.
8). Figure 10: The unit of wind stress curl unit should be “N.m-3”, so the colorbar will make some confuse, move “N.m-3” to the right side of colorbar or another proper place.
To compare AE1 and AE2, the same figure as Figure 10 but for AE2 is needed.
9). Figure 11: The first letter of “date” and “depth” needs to be capitalized.
3. There are some spelling or inappropriate use of singular and plural in the manuscript, for example,
L39 on ‘the’ one hand
L65 the typhoon track ‘are’ more intensely
L87 of a ‘near-inertial’ wake
L118 The daily Sea Level Anomaly (SLA) and geostrophic current data ‘are’ provided by Archiving
L131 ‘database’
L156 temperature and salinity ‘from’ 1 September to 30 September 2014 ‘were’ chosen to study.
L216 ‘where’
L278 ‘passage’
L398 warm anomaly of 1.2 ℃ ‘was’ observed at a depth
L444 ‘Compared’
L508 ‘contributes’
4. Inconsistent use of tenses. When describing the work of previous researchers, you should generally use the past tense. This is because those studies have been completed in the past and form part of the background for your research. When describing your own work, you should generally use the present tense. This helps emphasize that your results are current and still valid.
For example, L122 the data access needs to use the past tense.
L309-313 please use the past tense
L316-319 please use the present tense, etc
Please check the full manuscript carefully.
5. Many abbreviations have repeated definitions, including but not limited to:
L71 and L118 SLA duplication definitions.
'EPV' is firmly defined 4-5 times, ‘Rossby number’, ‘SST’, ‘EKE’, etc.
6. A mix of American and British spellings, such as Typhoon ‘center’ and ‘centre’ are appeared in the manuscript.
7. Line 650: Please check out the format of the reference.
Citation: https://doi.org/10.5194/egusphere-2023-1734-RC2 -
AC2: 'Reply on RC2', Xiayan Lin, 30 Oct 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1734/egusphere-2023-1734-AC2-supplement.pdf
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2023-1734', Anonymous Referee #1, 24 Aug 2023
I don’t think this paper is publishable; so sorry.
General Comments: Kalmaegi was a fast-moving TC. At 8 m/s, the TC traverses ~600 km in 1 day and spent ~6 hours traversing AE1 (or AE2) with a diameter of about 150 km. In such a super-critically moving storm, most of the wind effect on the ocean is therefore through mixing (including perhaps that caused by near-inertial internal wave breaking in the upper ocean in the wake of the storm) rather than the wind stress curl. The latter would require that wind acts on the ocean in a time scale longer than the inertial period (~1.5 days at 19N). I understand the authors' hypothesis of the negative WSC (thus convergence) on the left side, etc., but I don't think it is a demonstrable one in this case and is most likely incorrect. The increased AE1 after Kalmaegi (Fig.3, etc.) is likely a complex eddy adjustment process. One may suspect such adjustment also from Fig.3 in which the "warm" area between AE1 and AE2, including that on the left side, shrinks or weakens. That area would have expanded following the authors' hypothesis.
Two other general comments. 1) AE1’s increased amplitude, Ro and EKE = 1.3 cm, 1.4e-2 and 107 (cm/s)^2 are small. Are they statistically significant, and were errors and confidence levels estimated? Similarly for AE2. 2) Inertial oscillatory response persists long (~5 days and longer) after a storm passes (see e.g. Wu et al. Effect of Typhoon Kalmaegi (2014) on northern South China Sea explored using Muti-platform satellite and buoy observations data; Prog Oceanogr. 180 (2020) 102218). The effects of inertial motions on the Authors’ results and analyses were not discussed and I am unsure, for example, how the effects were filtered out or accounted for and how they may affect their estimates.
Other Comments:
L14: Rossby number (Ro = relative vorticity/Coriolis parameter);
L16: Rossby number;
L166: vertical feedback of the ocean by ... Kalmaegi: Not sure what this means, what "feedback", maybe "response..."?
Also: I assume GLORY assimilates Argo data but not the Station data. If so, then it is unsurprising that GLORY agrees with ARGO but not Station 5 (Figure 1).
Only Station 5 on the left side of the storm was used to support the authors' hypothesis. To support (refute?) the Authors' hypothesis I suggest using data from other Stations (except #3), right and left of Kalmaegi.
L223: ... weak wind stress curl, to be more precise. The term "wind shear" is also customarily taken as "vertical wind shear" in TC studies in meteorology so can be confusing.
L245: ... with 6-hourly dots.
.
.
-
AC1: 'Reply on RC1', Xiayan Lin, 30 Oct 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1734/egusphere-2023-1734-AC1-supplement.pdf
-
AC1: 'Reply on RC1', Xiayan Lin, 30 Oct 2023
-
RC2: 'Comment on egusphere-2023-1734', Anonymous Referee #2, 08 Sep 2023
General comments:
The authors investigated the responses of two warm eddies to a typhoon using observational and reanalysis data. There have been lots of efforts on eddy feedback to TC evolution, while our understanding of eddy response to TCs remains limited. The work is potentially interesting and contribute to broaden the knowledge of TC-eddy interaction, but I have some comments before the paper can be published. I recommend moderate to minor revision of the manuscript.
Primary comments:
- The motivation of conducting the study should be more clarified. Just stating that “However, there has been relatively limited exploration of different responses exhibited by warm eddies under the influence of typhoons” is not adequate from my opinion. There have been several studies on the eddy response to TCs. The authors should be more carefully summarize what have been reported from these previous studies, and what new knowledge will be reported in this study.
- The writing of the paper needs a substantial improvement. There are lots of sentences that are hard to follow and hinder understanding. The logics between paragraphs should be clear. On Line 31, the word of “typhoon” is used, but in the following the “tropical cyclone” is used instead. The paper should keep consistency in word usage.
Specific comments:
1. Is it reasonable to use the rectangle areas represent AE1 and AE2 (Figure 1)? As eddies always move during typhoon.
2. There are several common issues with the figures in the manuscript that need to be addressed, including the addition of x-labels and y-labels, as well as the unification of font sizes etc. Specific comments are as follows:
1). Figure 1: The first letter of “depth” in Y-label needs to be capitalized.
2). Figure 4: Just keep one arrow legend and text of ”15 m/s” in (a), the quiver and the text should be larger.
3). The coordinate axes are duplicated in Figure 5, delete the x-axis and y-axis in Figure 5 (a), (d), (g), (j), just like Figure 4; Set the range of SST colorbar as 26 to 31 °C; Change the red dots to larger black dots.
4). Figure 6: The first letter of “date” needs to be capitalized, like “Date”.
5). Figure 7: The first letter of “date” and “depth” needs to be capitalized; The unit of “psu” should be “PSU”.
6). Figure 8: The first letter of “date” and “depth” needs to be capitalized; Please use the density excess replace the density, that means density minus 1000 kg. m-3; The unit of buoyancy should be written as “N2 (10-4 s-2)”.
7). Figure 9: The first letter of “depth” needs to be capitalized; “psu” should be “PSU”.
8). Figure 10: The unit of wind stress curl unit should be “N.m-3”, so the colorbar will make some confuse, move “N.m-3” to the right side of colorbar or another proper place.
To compare AE1 and AE2, the same figure as Figure 10 but for AE2 is needed.
9). Figure 11: The first letter of “date” and “depth” needs to be capitalized.
3. There are some spelling or inappropriate use of singular and plural in the manuscript, for example,
L39 on ‘the’ one hand
L65 the typhoon track ‘are’ more intensely
L87 of a ‘near-inertial’ wake
L118 The daily Sea Level Anomaly (SLA) and geostrophic current data ‘are’ provided by Archiving
L131 ‘database’
L156 temperature and salinity ‘from’ 1 September to 30 September 2014 ‘were’ chosen to study.
L216 ‘where’
L278 ‘passage’
L398 warm anomaly of 1.2 ℃ ‘was’ observed at a depth
L444 ‘Compared’
L508 ‘contributes’
4. Inconsistent use of tenses. When describing the work of previous researchers, you should generally use the past tense. This is because those studies have been completed in the past and form part of the background for your research. When describing your own work, you should generally use the present tense. This helps emphasize that your results are current and still valid.
For example, L122 the data access needs to use the past tense.
L309-313 please use the past tense
L316-319 please use the present tense, etc
Please check the full manuscript carefully.
5. Many abbreviations have repeated definitions, including but not limited to:
L71 and L118 SLA duplication definitions.
'EPV' is firmly defined 4-5 times, ‘Rossby number’, ‘SST’, ‘EKE’, etc.
6. A mix of American and British spellings, such as Typhoon ‘center’ and ‘centre’ are appeared in the manuscript.
7. Line 650: Please check out the format of the reference.
Citation: https://doi.org/10.5194/egusphere-2023-1734-RC2 -
AC2: 'Reply on RC2', Xiayan Lin, 30 Oct 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1734/egusphere-2023-1734-AC2-supplement.pdf
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Yihao He
Guoqing Han
Yu Liu
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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