the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 08 Aug 2023
Measurement report: Influence of the Antarctic Ozone Hole in Southern Brazil: Conceptual model for 42 years of analysis the atmospheric dynamics on ozone
Abstract. The austral spring in the Southern Hemisphere presents temporary reductions in ozone content mainly in the Antarctic region known as the Antarctic Ozone Hole (AOH). However, studies show an influence in mid-latitude regions, such as southern Brazil, where days with temporary decreases in the total column ozone (TCO) are identified. The main objective of this work is to investigate this influence of AOH on the southern region of Brazil, using data from the TCO and vertical profiles that will help to identify the preferential height at which these decreases occur in southern Brazil, in addition to analyzing the atmospheric dynamic behavior during these events in the period 42 years of data (1979 to 2020). The methodology used comprises the analysis of average daily data of the total column of ozone through ground-based instruments (Brewer Spectrophotometer), satellite data (TOMS and OMI), and to compare reanalysis data from the ECMWF-ERA5, for the identification of events of influence of the AOH on the southern region of Brazil. The analysis of the vertical content of ozone (O3) data from the TIMED/SABER satellite provides daily data from 15 to 110 km in height and has 19 years of O3 profiles available in the period from 2002 to 2020. From this, 102 events were identified that influenced Santa Maria (29.4º S; 53.7º W), in the south of Brazil, with a temporary decrease in the ozone content in the period, where between 24.1–28 km of altitude the more significant reductions in O3 during events. In the dynamic analysis, the stratospheric fields showed an increase in the absolute potential vorticity, mainly in September and October. The conceptual models in the horizontal and vertical section of the atmosphere explain the action of the stratospheric and tropospheric jet during the occurrence of events of decrease in the O3 content in Santa Maria. It was possible to identify the strong influence on the development of these events through the connection of the stratospheric jet (polar vortex) with the tropospheric jets (polar and subtropical jet) at medium and high levels of the atmosphere.
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RC1: 'Comment on egusphere-2023-1471', Anonymous Referee #1, 05 Sep 2023
Review of Bittencourt et al., Measurement report: Influence of the Antarctic Ozone Hole in Southern Brazil: Conceptual model for 42 years of analysis the atmospheric dynamics on ozone
General Comments
The subject of the submitted manuscript is one of great interest, episodes of low total ozone observed in the city of Santa Maria in Brazil located at 29 degrees latitude, caused by filaments of stratospheric air originating in the Antarctic ozone hole.
The authors identify low ozone events using ground-based and satellite-based measurements of total ozone that are 1.5 standard deviations below the climatology, and then class these as of polar influence if the event is associated with an increase in the magnitude of potential vorticity. A case study is then presented in some detail of a noteworthy event of 20 October 2016, which I note has already been the subject of previous publication by the authors. Vertical profiles of the low ozone episodes are studied using SABER data, and finally some analysis is presented of the broader dynamic situation, with a focus on the stratospheric and tropospheric jets.
Unfortunately I believe the manuscript requires major revisions before it is suitable for publication.
It is not at all clear to me that there is anything new here compared to the authors' previous works on the same subject cited in the references (Bittencourt et. al 2018, Bittencourt et al. 2019, Bresciani et al. 2019, Peres et al. 2019). There is a large amount of overlap with these references.
Therefore, firstly, the new findings of this study need to be made much more explicit.
Secondly, the writing style in general needs to be made much easier for the reader to follow. Each section currently contains a large amount of background material and repetition before reaching the main point. I then often found it quite hard to find and understand the point being made, and what exactly was being said. I suggest shortening the background discussion and removing the repetition throughout the manuscript, and then using more text to explain your new findings more clearly.
Specific comments
Figure 10 is not described properly in the caption – from the text I think it shows the composite of 20 hPa PV for all low ozone events with low PV for each month? I think it would also be interesting to show the composite for low ozone events with high PV for comparison.
Figure 12 The figure caption says it is the 'monthly climatology', not just for low ozone events – is that correct? Figure 13 is very similar to figure 12 so it's hard to see that there is any difference in the position of the jets when there is low ozone event compared to the average situation.
Figure 13 doesn't look very similar to Figure 6 though, so does this mean the event in figure 6 doesn't show the usual pattern for low ozone events?
I am very confused about your "conceptual model" and I think it needs to be explained much more clearly. Figure 14 doesn't look at all like Figure 13.
Figure 14 appears to show ozone-poor air from inside the polar vortex moving across the width of the stratospheric polar jet (why would it do that?) then moving downwards between the two tropospheric jets to finish close to the surface at 700 hPa. This does not seem to have relevance to the rest of the study, because in the text, all the discussion has been about ozone at altitudes above 20 km.
Regarding the discussion of the QBO (lines 320-326), you need to show by a simple test that the difference between the number of events in the different phases is statistically significant.
Please follow the style guide (https://www.atmospheric-chemistry-and-physics.net/submission.html#english ) for the format of dates.
Citation: https://doi.org/10.5194/egusphere-2023-1471-RC1 - AC1: 'Reply on RC1', Gabriela Bittencourt, 11 Nov 2023
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AC4: 'Reply on RC1', Gabriela Bittencourt, 11 Nov 2023
The English correction of the manuscript has not yet been completed by the responsible company. We asked ACP for an extension of the response deadline precisely to send the corrected version, but the company has not yet completed the work. We apologize for this, and we will send the new corrected version as soon as possible.
Citation: https://doi.org/10.5194/egusphere-2023-1471-AC4
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RC2: 'Comment on egusphere-2023-1471', Anonymous Referee #2, 06 Sep 2023
This paper examines events where low ozone is observed over Southern Brazil over the last ~42 years, and identifies cases where such events can be attributed to transport of ozone-poor air from the Antarctic polar vortex during ozone hole season. The analysis centers on observations of total column ozone from a combination of ground-based and spaceborne sensors, supplemented by vertically resolved observations from TIMED SABER during the most recent two decades. ERA-5 reanalysis fields are used to diagnose the transport associated with these events and statistics are compiled.
Unfortunately, this paper needs a lot of work before it can be ready for publication. The discussion is hard to follow in many places. In particular, the manuscript spends a lot of time talking about findings of prior studies by the authors and others, and it is very challenging for a reader to discern what about this study is "new". Is it the addition of SABER data? The conceptual model? The inclusion of more years? I don't think it can be the application of the statistical analysis as that was covered in earlier papers. It would be best to have a clear discussion in the introduction of what was done/found previously and then briefly preview the new findings (or at least the new avenues of inquiry).
I have a list of specific concerns detailed below. Foremost among them is my serious questions about the author's "conceptual model", at least as described in Figure 14. Also, I am not convinced by authors argument that the "connection" of the various wind jets is key to the transport processes they describe. Such "connections" may indeed be important, but I do not believe the authors have provided sufficient evidence to demonstrate that. At best they have shown a correlation (though not quantified its statistical significance), but are there other such connection events that are not associated with changes in ozone? Similarly I am totally unclear what is meant by "funneling" in this context.
Finally, I'm afraid the standard of writing in this paper is rather poor, with inappropriate word choices and incorrect grammar throughout. I have highlighted some places where corrections are needed. However, this is far from a comprehensive list. Until this paper has received significant attention from a native English speaker and/or a copy editor, I'm afraid it will be unsuitable for publication on those grounds alone. That said, that alone is insufficient. The authors need to work hard to structure this paper more clearly, with the old and new material delineated, and the "case study" separated from the statistical work.
Specific comments:
Line 13: The sentence "In the dynamic analysis…" is very unclear. Do you mean something like "An analysis of the dynamics associated with these events found an increase in absolute potential vorticity…" (do we really need to call out the vertical and horizontal cross sections?).
Line 14: "The conceptual model" - this is the first time you're introducing it, so you should say "Our conceptual model". Also, again suggesting that this is a purely horizontal and vertical conceptual model feels odd here. You're conceptual model is for the whole atmosphere, you're just choosing to describe it with reference to those cross sections, but that's a detail in my view.
Line 15: "jet" -> "jets" I believe.
Line 16: "O3 content in Santa Maria" -> "Total ozone column above Santa Maria" surely, we're not talking about the air in the city at ground level.
Line 17/18: "medium and high levels in the atmosphere" is unacceptably vague. To some (e.g., space physicists) the "upper troposphere" would be considered "low", to others (e.g., boundary layer meteorologists) it would be considered "high". Be specific (e.g., "mid-stratosphere") or better still give approximate altitude ranges.
Line 20: I really don't know what is meant by "through the energy balance of the planet" in this context. It feels like it's stuck in the middle of a bunch of points about life on Earth. I suggest you delete it or reword the whole sentence for better organization and clarity.
Line 23: "most important" really!!!? Surely many would put oxygen higher on the list (or CO2 for that matter). Important yes, but you really can't say "most important".
Line 24: "About 90%"? I presume by this you mean that 90% of the atmospheric ozone is found in the stratosphere, but the way you've written it, it sounds like you're claiming a 90% mixing ratio in the stratosphere. Please reword.
Line 26: This is completely wrong. The BDC is relevant for the ozone hole yes, but it is highly misleading to cite dynamics as the fundamental cause of the ozone hole. Please instead talk about the role of chlorine and polar stratospheric clouds, and cite the paper by Solomon (and/or others) as you do later in the text.
Lines 30/31: Please clarify the vertical region over which this barrier applies (e.g., "from the upper troposphere and into the mesosphere" or wherever it is the case).
Line 33: "poor ozone" -> "ozone-poor"
Line 42: "according to" -> "as shown in"
Line 43: "figure 1" -> "Figure 1" for consistency with other parts of the paper (and with ACP standards I expect).
Line 41/42: A badly worded sentence, please rewrite.
Line 45: Delete comma after "radiation"
Line 50: Reword this sentence. As it is you are stating that the sun is made of spectrophotometers.
Line 53: Delete comma after "called"
Line 54: Move "to infer TCO" after "with a resolution of 0.5 nm"
Line 55: "This is made to prevent most of…" -> "This step is taken in order to reduce the majority of cloud interference…"
Line 67: "TOM'S" -> "TOMS"
Line 76: OMI is on the Aura satellite, not ERS-2!! (Also, not it's Aura, not AURA)
Line 82: See 76 (plus this is partly redundant with that earlier sentence)
Line 85: By "bands" do you mean spectral bands (in which case "channels") might be a better word, or view directions, in which case something like "pixels" might be better.
Line 103: Please explain whether (1) this interpolation is done by the SABER team or you and (2) why on Earth you felt the need to interpolate to such a fine resolution? This is way finer than any true information obtained by the SABER instrument. What difference did you find that made you pick this rather than sticking with the native SABER resolution or just using 1km?
Section 2.1.3. You should note that ERA-5 assimilates ozone column (from Aura OMI I believe) and ozone profile from Aura MLS - this will affect the ERA-5 ozone product, giving more realistic results following the 2004 Aura launch.
Line 129-133: A particularly clumsily worded pair of sentences.
Section 2.2: This section heading needs major rewording. Firstly, it should be "Criterion" (or Criteria if there is more than one of them). I suggest "Criteria for defining Antarctic ozone hole influence on events".
Line 135/136: This sentence is garbled. Please clarify.
Also, you need to make it clear whether the standard deviations are computed separately for each month (e.g., separate numbers for September 2020, September 2021, etc.), or for all the months together (i.e., computing the standard deviation for all the September days in the 42-year window). Not until you show us Figure 2 does it become somewhat clear that it is the latter, but I'm still not sure even now.
Line 159: I think you mean the annual "cycle" not "variability", right? Even then I would tone it down and change "stands out" to "is clear"
Line 161: You already defined the BDC (but then again, you'll probably be dropping that discussion earlier, so perhaps keep it here).
Line 171/172: This sentence is a pure assertion with no evidence given to back it up. Please work on a justification. In any case, change "Despite not being such a low value" to "Despite not being a particularly weak correlation"
Line 175: "unlike" -> "in contrast with".
Line 175: "at high levels of the atmosphere" is way too vague (as before). Be specific about the region (e.g., upper stratosphere?) and/or quote altitudes.
Line 177: Not sure about "as a function of" do you mean more like "driven by"?
Line 201 (and elsewhere): Why do you use the term "secondary"? Is it to distinguish it from the ozone hole itself. If so, I find it confusing, as I keep thinking you're referring to a double dip in the ozone over your site. I suggest dropping this terminology.
Line 202: I suggest breaking the sentence after the Bresciani reference. Have a period, then drop the "after".
Line 205: "AURA" -> "Aura". But Aura is not an instrument it is a mission. Please name the Aura instrument (MLS? HIRDLS? OMI?) to be parallel with your reference to SABER rather than TIMED.
Line 207: "BREWER" -> "Brewer"
Line 221: What do you mean by flaws in the data? If it's just the gaps then say gaps (or don't bother with this thought, you only mentioned it a few sentences ago). If you mean something else, then be more specific.
Line 227 (and associated figures): I think you'd be far better off showing volume mixing ratio rather than partial pressure as it is conserved following air motions, which is the story you're attempting to tell. That is the unit that atmospheric chemists prefer.
Line 234: "high values of reduction" is confusing. "large reductions" would be clearer.
Section 3.3: The start of this section reads like you're still in the case study, in which case it should be 3.2.2 (indeed, you should not have a 3.2.1 if you don't have a 3.2.2). But then you change to talk about the statistics. I suggest you rearrange/split this section to separate the remnants of the case study from the statistics discussion.
Line 277: "Figure ??" - insert correct cross reference
Line 280: "These large scale systems help to understand…" poor wording, these systems cannot help anyone understand anything (it's like saying "Thursday can help to understand"), what is it about these systems that you are using to illustrate our understanding.
Line 320 and associated discussion: Please verify whether these differences are statistically significant.
Line 335: I would not say "lowest occurrence" - it's only lowest among the months you've chosen. Presumably April is lower still, right?
Line 338: "most intermediate", again, be specific
Line 344: "it was established to analyze" - poor wording
Lines 347/348: The sentence "Regarding the climatology…" is confusingly worded. It sounds like you're saying that the climatology stands out against the climatology.
Lines 364/365: This description is very vague. How precisely is this calculation performed. Is it for all the days outside your 1.5-sigma threshold, or some fixed-length window around a central day. Is it a straight composite thereafter? More detail is needed.
Lines 366-368: Badly worded sentence. You refer to Figures 10b and 10c as if they tell us that September and October stand out with the most events, but the figures do not show that. Also, you should put the pointer to the figures in parentheses or have a comma after 10c in this case.
Line 383: I have no idea what "isentropic ones" means in this case. Nor what you mean by "funneling". You need to point to specific featurein the plot. Are the contours getting closer? (Not really to my eye). This is your key point (or at least I think you want it to be) and yet I'm struggling to see what you see. Help the reader out!
Lines 383 and 395. The Santos and Rodriguez citations should not be in parentheses (use \citet rather than \citep in LaTeX).
Line 398: Negative temperature????!!! (do you mean negative anomaly?)
Line 402: Medium atmospheric levels again - be specific
Line 404: Again, please tell me where I am supposed to see "isentropic coupling" - what is coupled to what in what figure?
Line 406 to 407: I am far from convinced by this argument. You need to compute trajectories or similar. Also, as discussed, you have not shown (unless I missed it) that there are not other such "coupling" events that do not result in low ozone. Until you show that, what you have shown could just be coincidence. In any case, correlation does not imply causation (you need to demonstrate that this is not the "post hoc ergo propter hoc" fallacy).
Line 412: Again, I don't know what you mean by funneling. In any case "funneling of isentropic <what>". Do you mean funneling of the isentropes? I still don't really get what that means.
Line 413: "As shown"? Not really, at best it is "as illustrated" or (as you draw it). Also, see my notes on Figure 14.
Conclusions - I held short of commenting on these, pending all the work described above that is needed to verify that the conclusions you are drawing can be drawn.
Figure 2: I'd suggest you artificially stagger the different datasets by a few days so the error bars can be more readily distinguished (make a note in the caption that you've done so).
Figure 4: As discussed, I urge you to plot in this in vmr, perhaps as a function of pressure (or better yet, potential temperature) rather than altitude. You do not comment on the huge anomaly below 22km. It's possible this is dynamical and will go away when plotted in vmr (another reason to do so). Otherwise, please explain this, as it's far more remarkable than the feature you're focusing on.
Figure 5: My understanding is that it is far better to plot PV on a potential temperature surface. It changes rapidly in the vertical and the features you show may reflect that rather than true dynamics.
Figure 6: By "jet stream" in the caption do you mean winds? If so, say so? Is it just zonal wind? If so, say so. What are the thin lines with arrows on? Are they some measure of stream function? What does their density signify? Why are they not densest where the jets are strongest? Last sentence of the caption is completely unintelligible to me. Is it supposed to talking about where your station is?
Figure 8: Again plot in vmr rather than partial pressure.
Figure 10: Again, you should plot this on a potential temperature surface. Also give more detail in the caption and/or the text on how this anomaly composite (if that's what it is) is computed.
Figure 12: See comments on Figure 6
Figure 13: As figure 12.
Figure 14: What do the lines with arrows mean in both plots? In particular for 14b, are they supposed to denote some kind of motion (so the x-axis is time as much as it is latitude?). If so, this is completely unbelievable. I do not for a moment think that ozone can be transported from ~10hPa down to ~500hPa, as you imply, over this latitude range or any kind of vortex transport timescale. Your work refers only to stratospheric phenomena, this diagram describes a completely different (and in my view unrealistic) process.
Citation: https://doi.org/10.5194/egusphere-2023-1471-RC2 - AC2: 'Reply on RC2', Gabriela Bittencourt, 11 Nov 2023
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AC5: 'Reply on RC2', Gabriela Bittencourt, 11 Nov 2023
The English correction of the manuscript has not yet been completed by the responsible company. We asked ACP for an extension of the response deadline precisely to send the corrected version, but the company has not yet completed the work. We apologize for this, and we will send the new corrected version as soon as possible.
Citation: https://doi.org/10.5194/egusphere-2023-1471-AC5
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EC1: 'Comment on egusphere-2023-1471', Jens-Uwe Grooß, 13 Sep 2023
Please note the data policy of ACP, see e.g. here https://www.atmospheric-chemistry-and-physics.net/policies/data_policy.html
The underlying data of the paper need to be public.
However, it seems that under station number 529 on https://woudc.org/data/stations/index.php?lang=en
there are no data available.
Please clarify this issue.Citation: https://doi.org/10.5194/egusphere-2023-1471-EC1 -
AC3: 'Reply on EC1', Gabriela Bittencourt, 11 Nov 2023
Data from station 529 is not yet available, we are still processing this data on the WOUDC website.
Therefore, in accordance with ACP standards, we created a DOI to make the data used in this manuscript available.
Below is the link for public consultation of TCO data from the Brewer Spectrophotometer in Santa Maria.https://zenodo.org/records/10019128
Citation: https://doi.org/10.5194/egusphere-2023-1471-AC3
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AC3: 'Reply on EC1', Gabriela Bittencourt, 11 Nov 2023
Status: closed
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RC1: 'Comment on egusphere-2023-1471', Anonymous Referee #1, 05 Sep 2023
Review of Bittencourt et al., Measurement report: Influence of the Antarctic Ozone Hole in Southern Brazil: Conceptual model for 42 years of analysis the atmospheric dynamics on ozone
General Comments
The subject of the submitted manuscript is one of great interest, episodes of low total ozone observed in the city of Santa Maria in Brazil located at 29 degrees latitude, caused by filaments of stratospheric air originating in the Antarctic ozone hole.
The authors identify low ozone events using ground-based and satellite-based measurements of total ozone that are 1.5 standard deviations below the climatology, and then class these as of polar influence if the event is associated with an increase in the magnitude of potential vorticity. A case study is then presented in some detail of a noteworthy event of 20 October 2016, which I note has already been the subject of previous publication by the authors. Vertical profiles of the low ozone episodes are studied using SABER data, and finally some analysis is presented of the broader dynamic situation, with a focus on the stratospheric and tropospheric jets.
Unfortunately I believe the manuscript requires major revisions before it is suitable for publication.
It is not at all clear to me that there is anything new here compared to the authors' previous works on the same subject cited in the references (Bittencourt et. al 2018, Bittencourt et al. 2019, Bresciani et al. 2019, Peres et al. 2019). There is a large amount of overlap with these references.
Therefore, firstly, the new findings of this study need to be made much more explicit.
Secondly, the writing style in general needs to be made much easier for the reader to follow. Each section currently contains a large amount of background material and repetition before reaching the main point. I then often found it quite hard to find and understand the point being made, and what exactly was being said. I suggest shortening the background discussion and removing the repetition throughout the manuscript, and then using more text to explain your new findings more clearly.
Specific comments
Figure 10 is not described properly in the caption – from the text I think it shows the composite of 20 hPa PV for all low ozone events with low PV for each month? I think it would also be interesting to show the composite for low ozone events with high PV for comparison.
Figure 12 The figure caption says it is the 'monthly climatology', not just for low ozone events – is that correct? Figure 13 is very similar to figure 12 so it's hard to see that there is any difference in the position of the jets when there is low ozone event compared to the average situation.
Figure 13 doesn't look very similar to Figure 6 though, so does this mean the event in figure 6 doesn't show the usual pattern for low ozone events?
I am very confused about your "conceptual model" and I think it needs to be explained much more clearly. Figure 14 doesn't look at all like Figure 13.
Figure 14 appears to show ozone-poor air from inside the polar vortex moving across the width of the stratospheric polar jet (why would it do that?) then moving downwards between the two tropospheric jets to finish close to the surface at 700 hPa. This does not seem to have relevance to the rest of the study, because in the text, all the discussion has been about ozone at altitudes above 20 km.
Regarding the discussion of the QBO (lines 320-326), you need to show by a simple test that the difference between the number of events in the different phases is statistically significant.
Please follow the style guide (https://www.atmospheric-chemistry-and-physics.net/submission.html#english ) for the format of dates.
Citation: https://doi.org/10.5194/egusphere-2023-1471-RC1 - AC1: 'Reply on RC1', Gabriela Bittencourt, 11 Nov 2023
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AC4: 'Reply on RC1', Gabriela Bittencourt, 11 Nov 2023
The English correction of the manuscript has not yet been completed by the responsible company. We asked ACP for an extension of the response deadline precisely to send the corrected version, but the company has not yet completed the work. We apologize for this, and we will send the new corrected version as soon as possible.
Citation: https://doi.org/10.5194/egusphere-2023-1471-AC4
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RC2: 'Comment on egusphere-2023-1471', Anonymous Referee #2, 06 Sep 2023
This paper examines events where low ozone is observed over Southern Brazil over the last ~42 years, and identifies cases where such events can be attributed to transport of ozone-poor air from the Antarctic polar vortex during ozone hole season. The analysis centers on observations of total column ozone from a combination of ground-based and spaceborne sensors, supplemented by vertically resolved observations from TIMED SABER during the most recent two decades. ERA-5 reanalysis fields are used to diagnose the transport associated with these events and statistics are compiled.
Unfortunately, this paper needs a lot of work before it can be ready for publication. The discussion is hard to follow in many places. In particular, the manuscript spends a lot of time talking about findings of prior studies by the authors and others, and it is very challenging for a reader to discern what about this study is "new". Is it the addition of SABER data? The conceptual model? The inclusion of more years? I don't think it can be the application of the statistical analysis as that was covered in earlier papers. It would be best to have a clear discussion in the introduction of what was done/found previously and then briefly preview the new findings (or at least the new avenues of inquiry).
I have a list of specific concerns detailed below. Foremost among them is my serious questions about the author's "conceptual model", at least as described in Figure 14. Also, I am not convinced by authors argument that the "connection" of the various wind jets is key to the transport processes they describe. Such "connections" may indeed be important, but I do not believe the authors have provided sufficient evidence to demonstrate that. At best they have shown a correlation (though not quantified its statistical significance), but are there other such connection events that are not associated with changes in ozone? Similarly I am totally unclear what is meant by "funneling" in this context.
Finally, I'm afraid the standard of writing in this paper is rather poor, with inappropriate word choices and incorrect grammar throughout. I have highlighted some places where corrections are needed. However, this is far from a comprehensive list. Until this paper has received significant attention from a native English speaker and/or a copy editor, I'm afraid it will be unsuitable for publication on those grounds alone. That said, that alone is insufficient. The authors need to work hard to structure this paper more clearly, with the old and new material delineated, and the "case study" separated from the statistical work.
Specific comments:
Line 13: The sentence "In the dynamic analysis…" is very unclear. Do you mean something like "An analysis of the dynamics associated with these events found an increase in absolute potential vorticity…" (do we really need to call out the vertical and horizontal cross sections?).
Line 14: "The conceptual model" - this is the first time you're introducing it, so you should say "Our conceptual model". Also, again suggesting that this is a purely horizontal and vertical conceptual model feels odd here. You're conceptual model is for the whole atmosphere, you're just choosing to describe it with reference to those cross sections, but that's a detail in my view.
Line 15: "jet" -> "jets" I believe.
Line 16: "O3 content in Santa Maria" -> "Total ozone column above Santa Maria" surely, we're not talking about the air in the city at ground level.
Line 17/18: "medium and high levels in the atmosphere" is unacceptably vague. To some (e.g., space physicists) the "upper troposphere" would be considered "low", to others (e.g., boundary layer meteorologists) it would be considered "high". Be specific (e.g., "mid-stratosphere") or better still give approximate altitude ranges.
Line 20: I really don't know what is meant by "through the energy balance of the planet" in this context. It feels like it's stuck in the middle of a bunch of points about life on Earth. I suggest you delete it or reword the whole sentence for better organization and clarity.
Line 23: "most important" really!!!? Surely many would put oxygen higher on the list (or CO2 for that matter). Important yes, but you really can't say "most important".
Line 24: "About 90%"? I presume by this you mean that 90% of the atmospheric ozone is found in the stratosphere, but the way you've written it, it sounds like you're claiming a 90% mixing ratio in the stratosphere. Please reword.
Line 26: This is completely wrong. The BDC is relevant for the ozone hole yes, but it is highly misleading to cite dynamics as the fundamental cause of the ozone hole. Please instead talk about the role of chlorine and polar stratospheric clouds, and cite the paper by Solomon (and/or others) as you do later in the text.
Lines 30/31: Please clarify the vertical region over which this barrier applies (e.g., "from the upper troposphere and into the mesosphere" or wherever it is the case).
Line 33: "poor ozone" -> "ozone-poor"
Line 42: "according to" -> "as shown in"
Line 43: "figure 1" -> "Figure 1" for consistency with other parts of the paper (and with ACP standards I expect).
Line 41/42: A badly worded sentence, please rewrite.
Line 45: Delete comma after "radiation"
Line 50: Reword this sentence. As it is you are stating that the sun is made of spectrophotometers.
Line 53: Delete comma after "called"
Line 54: Move "to infer TCO" after "with a resolution of 0.5 nm"
Line 55: "This is made to prevent most of…" -> "This step is taken in order to reduce the majority of cloud interference…"
Line 67: "TOM'S" -> "TOMS"
Line 76: OMI is on the Aura satellite, not ERS-2!! (Also, not it's Aura, not AURA)
Line 82: See 76 (plus this is partly redundant with that earlier sentence)
Line 85: By "bands" do you mean spectral bands (in which case "channels") might be a better word, or view directions, in which case something like "pixels" might be better.
Line 103: Please explain whether (1) this interpolation is done by the SABER team or you and (2) why on Earth you felt the need to interpolate to such a fine resolution? This is way finer than any true information obtained by the SABER instrument. What difference did you find that made you pick this rather than sticking with the native SABER resolution or just using 1km?
Section 2.1.3. You should note that ERA-5 assimilates ozone column (from Aura OMI I believe) and ozone profile from Aura MLS - this will affect the ERA-5 ozone product, giving more realistic results following the 2004 Aura launch.
Line 129-133: A particularly clumsily worded pair of sentences.
Section 2.2: This section heading needs major rewording. Firstly, it should be "Criterion" (or Criteria if there is more than one of them). I suggest "Criteria for defining Antarctic ozone hole influence on events".
Line 135/136: This sentence is garbled. Please clarify.
Also, you need to make it clear whether the standard deviations are computed separately for each month (e.g., separate numbers for September 2020, September 2021, etc.), or for all the months together (i.e., computing the standard deviation for all the September days in the 42-year window). Not until you show us Figure 2 does it become somewhat clear that it is the latter, but I'm still not sure even now.
Line 159: I think you mean the annual "cycle" not "variability", right? Even then I would tone it down and change "stands out" to "is clear"
Line 161: You already defined the BDC (but then again, you'll probably be dropping that discussion earlier, so perhaps keep it here).
Line 171/172: This sentence is a pure assertion with no evidence given to back it up. Please work on a justification. In any case, change "Despite not being such a low value" to "Despite not being a particularly weak correlation"
Line 175: "unlike" -> "in contrast with".
Line 175: "at high levels of the atmosphere" is way too vague (as before). Be specific about the region (e.g., upper stratosphere?) and/or quote altitudes.
Line 177: Not sure about "as a function of" do you mean more like "driven by"?
Line 201 (and elsewhere): Why do you use the term "secondary"? Is it to distinguish it from the ozone hole itself. If so, I find it confusing, as I keep thinking you're referring to a double dip in the ozone over your site. I suggest dropping this terminology.
Line 202: I suggest breaking the sentence after the Bresciani reference. Have a period, then drop the "after".
Line 205: "AURA" -> "Aura". But Aura is not an instrument it is a mission. Please name the Aura instrument (MLS? HIRDLS? OMI?) to be parallel with your reference to SABER rather than TIMED.
Line 207: "BREWER" -> "Brewer"
Line 221: What do you mean by flaws in the data? If it's just the gaps then say gaps (or don't bother with this thought, you only mentioned it a few sentences ago). If you mean something else, then be more specific.
Line 227 (and associated figures): I think you'd be far better off showing volume mixing ratio rather than partial pressure as it is conserved following air motions, which is the story you're attempting to tell. That is the unit that atmospheric chemists prefer.
Line 234: "high values of reduction" is confusing. "large reductions" would be clearer.
Section 3.3: The start of this section reads like you're still in the case study, in which case it should be 3.2.2 (indeed, you should not have a 3.2.1 if you don't have a 3.2.2). But then you change to talk about the statistics. I suggest you rearrange/split this section to separate the remnants of the case study from the statistics discussion.
Line 277: "Figure ??" - insert correct cross reference
Line 280: "These large scale systems help to understand…" poor wording, these systems cannot help anyone understand anything (it's like saying "Thursday can help to understand"), what is it about these systems that you are using to illustrate our understanding.
Line 320 and associated discussion: Please verify whether these differences are statistically significant.
Line 335: I would not say "lowest occurrence" - it's only lowest among the months you've chosen. Presumably April is lower still, right?
Line 338: "most intermediate", again, be specific
Line 344: "it was established to analyze" - poor wording
Lines 347/348: The sentence "Regarding the climatology…" is confusingly worded. It sounds like you're saying that the climatology stands out against the climatology.
Lines 364/365: This description is very vague. How precisely is this calculation performed. Is it for all the days outside your 1.5-sigma threshold, or some fixed-length window around a central day. Is it a straight composite thereafter? More detail is needed.
Lines 366-368: Badly worded sentence. You refer to Figures 10b and 10c as if they tell us that September and October stand out with the most events, but the figures do not show that. Also, you should put the pointer to the figures in parentheses or have a comma after 10c in this case.
Line 383: I have no idea what "isentropic ones" means in this case. Nor what you mean by "funneling". You need to point to specific featurein the plot. Are the contours getting closer? (Not really to my eye). This is your key point (or at least I think you want it to be) and yet I'm struggling to see what you see. Help the reader out!
Lines 383 and 395. The Santos and Rodriguez citations should not be in parentheses (use \citet rather than \citep in LaTeX).
Line 398: Negative temperature????!!! (do you mean negative anomaly?)
Line 402: Medium atmospheric levels again - be specific
Line 404: Again, please tell me where I am supposed to see "isentropic coupling" - what is coupled to what in what figure?
Line 406 to 407: I am far from convinced by this argument. You need to compute trajectories or similar. Also, as discussed, you have not shown (unless I missed it) that there are not other such "coupling" events that do not result in low ozone. Until you show that, what you have shown could just be coincidence. In any case, correlation does not imply causation (you need to demonstrate that this is not the "post hoc ergo propter hoc" fallacy).
Line 412: Again, I don't know what you mean by funneling. In any case "funneling of isentropic <what>". Do you mean funneling of the isentropes? I still don't really get what that means.
Line 413: "As shown"? Not really, at best it is "as illustrated" or (as you draw it). Also, see my notes on Figure 14.
Conclusions - I held short of commenting on these, pending all the work described above that is needed to verify that the conclusions you are drawing can be drawn.
Figure 2: I'd suggest you artificially stagger the different datasets by a few days so the error bars can be more readily distinguished (make a note in the caption that you've done so).
Figure 4: As discussed, I urge you to plot in this in vmr, perhaps as a function of pressure (or better yet, potential temperature) rather than altitude. You do not comment on the huge anomaly below 22km. It's possible this is dynamical and will go away when plotted in vmr (another reason to do so). Otherwise, please explain this, as it's far more remarkable than the feature you're focusing on.
Figure 5: My understanding is that it is far better to plot PV on a potential temperature surface. It changes rapidly in the vertical and the features you show may reflect that rather than true dynamics.
Figure 6: By "jet stream" in the caption do you mean winds? If so, say so? Is it just zonal wind? If so, say so. What are the thin lines with arrows on? Are they some measure of stream function? What does their density signify? Why are they not densest where the jets are strongest? Last sentence of the caption is completely unintelligible to me. Is it supposed to talking about where your station is?
Figure 8: Again plot in vmr rather than partial pressure.
Figure 10: Again, you should plot this on a potential temperature surface. Also give more detail in the caption and/or the text on how this anomaly composite (if that's what it is) is computed.
Figure 12: See comments on Figure 6
Figure 13: As figure 12.
Figure 14: What do the lines with arrows mean in both plots? In particular for 14b, are they supposed to denote some kind of motion (so the x-axis is time as much as it is latitude?). If so, this is completely unbelievable. I do not for a moment think that ozone can be transported from ~10hPa down to ~500hPa, as you imply, over this latitude range or any kind of vortex transport timescale. Your work refers only to stratospheric phenomena, this diagram describes a completely different (and in my view unrealistic) process.
Citation: https://doi.org/10.5194/egusphere-2023-1471-RC2 - AC2: 'Reply on RC2', Gabriela Bittencourt, 11 Nov 2023
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AC5: 'Reply on RC2', Gabriela Bittencourt, 11 Nov 2023
The English correction of the manuscript has not yet been completed by the responsible company. We asked ACP for an extension of the response deadline precisely to send the corrected version, but the company has not yet completed the work. We apologize for this, and we will send the new corrected version as soon as possible.
Citation: https://doi.org/10.5194/egusphere-2023-1471-AC5
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EC1: 'Comment on egusphere-2023-1471', Jens-Uwe Grooß, 13 Sep 2023
Please note the data policy of ACP, see e.g. here https://www.atmospheric-chemistry-and-physics.net/policies/data_policy.html
The underlying data of the paper need to be public.
However, it seems that under station number 529 on https://woudc.org/data/stations/index.php?lang=en
there are no data available.
Please clarify this issue.Citation: https://doi.org/10.5194/egusphere-2023-1471-EC1 -
AC3: 'Reply on EC1', Gabriela Bittencourt, 11 Nov 2023
Data from station 529 is not yet available, we are still processing this data on the WOUDC website.
Therefore, in accordance with ACP standards, we created a DOI to make the data used in this manuscript available.
Below is the link for public consultation of TCO data from the Brewer Spectrophotometer in Santa Maria.https://zenodo.org/records/10019128
Citation: https://doi.org/10.5194/egusphere-2023-1471-AC3
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AC3: 'Reply on EC1', Gabriela Bittencourt, 11 Nov 2023
Data sets
TCO by Brewer Spectrophotometer at Santa Maria Station José Valentin Bageston https://woudc.org/data/stations/index.php?lang=en
TCO by TOMS satellite data Richard D. McPeters, P. K. Bhartia, and Arlin J. Krueger, and Jay R. Herman https://ozoneaq.gsfc.nasa.gov/data/toms/
TCO by OMI satellite data Michael M. Yan https://aura.gsfc.nasa.gov/omi.html/
Ozone vertical profile by TIMED/SABER James M. Russell III https://data.gats-inc.com/saber/custom/Temp_O3_H2O/v2.0/
ECMWF-ERA5 meteorological data Hans Hersbach https://cds.climate.copernicus.eu/cdsapp#!/dataset/10.24381/cds.bd0915c6
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