Lagrangian simulations of the transport of young air masses to the top of the Asian monsoon anticyclone and into the tropical pipe

Vogel, Bärbel; Müller, Rolf; Günther, Gebhard; Spang, Reinhold; Hanumanthu, Sreeharsha; Li, Dan; Riese, Martin; Stiller, Gabriele P.

doi:https://doi.org/10.5194/acp-19-6007-2019

Articles | Volume 19, issue 9

https://doi.org/10.5194/acp-19-6007-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

StratoClim stratospheric and upper tropospheric processes...

https://doi.org/10.5194/acp-19-6007-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 9

Research article

|

08 May 2019

Research article |

| 08 May 2019

Lagrangian simulations of the transport of young air masses to the top of the Asian monsoon anticyclone and into the tropical pipe

Bärbel Vogel, Rolf Müller, Gebhard Günther, Reinhold Spang, Sreeharsha Hanumanthu, Dan Li, Martin Riese, and Gabriele P. Stiller

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Final revised paper (published on 08 May 2019)
Preprint (discussion started on 30 Jul 2018)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'Review of “Lagrangian simulations of the transport of young air masses to the top of the Asian monsoon anticyclone and into the tropical pipe” by Vogel et al.', Anonymous Referee #1, 14 Aug 2018
- AC1: 'Author Comment to Referee #1', Bärbel Vogel, 23 Nov 2018
RC2: 'Review for "Lagrangian simulations of the transport of young air masses to the top of the Asian monsoon anticyclone and into the tropical pipe" by B. Vogel et al.', Anonymous Referee #2, 14 Aug 2018
- AC2: 'Author Comment to Referee #2', Bärbel Vogel, 23 Nov 2018
RC3: 'Review of “Lagrangian simulations of the transport of young air masses to the top of the Asian monsoon anticyclone and into the tropical pipe” by Bärbel Vogel et al.', Anonymous Referee #3, 25 Sep 2018
- AC3: 'Author Comment to Referee #3', Bärbel Vogel, 23 Nov 2018

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Bärbel Vogel on behalf of the Authors (23 Nov 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (30 Dec 2018) by Peter Haynes

RR by Michelle Santee (15 Jan 2019)

Suggestions for revision or reasons for rejection

The authors have made quite a number of modifications to the manuscript in response to the comments of the three referees. Most notably, they have substantially rearranged / rewritten the Discussion section (Section 4). There and elsewhere in the paper they have done a much better job of clearly summarizing their major findings and appropriately placing them into the context of previously reported results. For the most part I feel that the reviewers’ concerns have been adequately addressed. I have only a few remaining suggestions (mostly minor wording changes where edits or additions were made during revision) that I feel should be considered before publication.

Specific comments:

P2, L18: are breaking --> break

P2, L22: ATAL --> the ATAL

P2, L32 - P3, L1: The conclusions of Bourassa et al. [2012] are accurately characterized here. However, their contention that the plume from the Nabro eruption only attained stratospheric altitudes through transport processes associated with deep convection in the Asian summer monsoon has been disproved by several subsequent publications, including Vernier et al. [Science, 2013], Fromm et al. [Science, 2013; JGR-A, 2014], and Fairlie et al. [ACP, 2014]. I feel that it is important to balance the assertions of Bourassa et al. reported in these sentences by noting that later studies showed that Nabro did in fact result in direct lower stratospheric (i.e., above 380 K) injection of volcanic aerosol, calling into question the critical role of monsoon convection in transporting volcanic aerosol from Nabro into the stratosphere. I have no objection to the more general statement in Section 4.1 (P16, L22-24; also present in the original submitted version) that the monsoon anticyclone affects the transport of volcanic sulphate aerosol, but these two sentences in the Introduction specifically about Nabro and the conclusions of Bourassa et al. need to either be amended to present the full picture or deleted.

P3, L16: both “2008” and “normal” are repeated twice in this sentence. I think it would read better as: “Further, there was a normal monsoon season in terms of rainfall over India in summer 2008.”

P4, L5: a second --> and a second

P4, L32: greater than 380 K --> above 380 K; add a comma after the parenthetical in this line (before “which”)

P5, L15 and L21: The authors might consider slightly rewording here to avoid starting two paragraphs in a row with the same phrase (“In the two-monsoon-season simulation”)

P7, L15: intercomparions --> intercomparisons

P7, L26-34: I appreciate that information about the MIPAS HCFC-22 data quality has been added. However, three sentences on measurement precision and total uncertainty have been stuck in between sentences on vertical resolution. Similarly, a sentence on horizontal resolution has been inserted between statements about vertical resolution. This paragraph would flow much better if first measurement uncertainty were covered, then horizontal resolution, and then all statements pertaining to vertical resolution were grouped together. Also, “consistent to” should be “consistent with” (L29).

P8, L7-8: “weaker” might be better than “less strong”; consequences on --> consequences for

P8, L15-16: 1 May 2008 until end of October --> 1 May 2008, running through the end of October

P8, L16: a strong --> strong

P9, L8: CO has already been used on p5 (L1), so this definition should be moved there (or deleted)

P9, L13: high contribution --> large contribution; fractions --> fractions of

P9, L31: features at --> features in; add a comma after “prominent”

P10, L6-7: shows --> show; Sect. 2.4) and longitude --> Sect. 2.4); also shown are the longitude

P10, L11: distribution --> distributions

P11, L8: The horizontal distribution of the tropical adjacent regions compared to the --> The comparison between the horizontal distribution of the tropical adjacent regions and the

P11, L11: the anticyclone and at 400K within --> the anticyclone, while at 400K they are found within

P11, L12: both tracers India/China and tropical adjacent regions show --> both the India/China and the tropical adjacent region tracers show

P12, L20: is ranging --> ranges

P12, L23: move “therefore” to after “anticyclone,”

P12, L33: pattern --> patterns

P13, L3 and L16: 20 day --> 20 days

P13, L9: “is inhomogeneous and not homogeneously distributed” seems redundant to me -- isn’t just saying “is not homogeneously distributed” sufficient?

P14, L3: insignificant weak --> insignificantly weak

P14, L5 and L9: “tropical AR”: either fully write out tropical adjacent regions (as done in most other places in the manuscript) or use the acronym TAR here

P14, L7-8: similar as for --> similar to that for the

P14, L10: larger than from --> larger than that from

P14, L11: details --> for details

P14, L16: reanalysis --> reanalyses

P15, L1: transport --> transport of

P15, L23: Fig. 13 (top) --> (Fig. 13 (top)) -- or label the panels as is done in other figures so that this could be (Fig. 13a)

P15, L28-29: Lower fractions are from tropical the Indian --> Smaller fractions are estimated for the tropical Indian

P15, L30: are lower --> are each smaller

P16, L10: a debate --> debate

P16, L12: depending on the used reanalysis data --> depending on the reanalysis data used

P16, L13: there is a strong intraseasonal variability of boundary source regions --> there is strong intraseasonal variability in the contributions of different boundary layer source regions

P16, L18: I found the wording “Further, in addition to previous studies, we” awkward and confusing, and I don’t think that it is exactly what the authors want to say. Rather, I think they mean something along the lines of “Further, going a step beyond previous studies, we”

P17, L8: This sentence (“… into the outer anticyclonic flow of the anticyclone follow the flow around the anticyclone”) is hard to read because there are too many instances of “anticyclone” or “anticyclonic -- are they all strictly necessary?

P17, L22-23: found a --> found; fractions around --> fractions of around

P17, L24: consistent to --> consistent with; about 6% contributions --> about a 6% contribution

P17, L26: Similar to the comment above about P16, L18, I don’t think that “in addition to” is quite right here -- I think it would be better to say something like “However, going beyond the results of Randel and Ploeger, we”

P18, L9: is calculated, resulting in up to 44% at 360K (up to 35% at 380 K) end of October --> was calculated to result in up to 44% young air at 360K (up to 35% at 380 K) at the end of October

P18, L12-13: end of October --> at the end of October; also delete “compared to 2012” and change “This difference is” to “The differences between 2008 and 2012 are”

P19, L1: consistent to --> consistent with

P19, L5: a anticyclonic --> an anticyclonic

P20, L7: add a semicolon after “months)”

P20, L18: regions --> region

P38, Fig. 10 caption: Southeast Asia (SEA) --> tropical adjacent regions (TAR)

P40, Fig. 13 caption: marked the vertical doted lines --> marked by the vertical dotted lines

P41, Fig. 14 caption: add a semicolon after “months)”; pipe which isolates tropical air masses largely --> pipe, which largely isolates tropical air masses

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RR by Anonymous Referee #2 (24 Jan 2019)

Suggestions for revision or reasons for rejection

Dear Authors,

thank you for considering my previous comments. I am pleased with the revised version of the manuscript. In particular, with the better linking to previous results in the published literature especially within the updated discussion section and the conclusions, which was my major concern with the publication. However, I still would like to see some minor (and in part technical) corrections before the manuscript can be published from my point of view. The corresponding comments are given below. Here, the page, line and figure numbers are those of the ACPD version of the manuscript. If (R1) is appended the numbers refer to the revised version.

Additional minor comments:

Figure A1 (R1): Revise the figure caption. Remove that the trajectories are started on "18 August 2008".

P1 L17: Please clarify which conditions you mean with: "...under these conditions."

These comments refer to my previous comments on the ACPD version of the manuscript and are listed in the respective section.

Regarding previous "General comments":

P19 L24 (R1): Upward transport in the edge region is clear at 440K from Fig.8 (R1). If only 440K is meant then write at 440K.

Thank you for your comment. Please, consider to add parts of your clarification regarding the transport on the eastern and western side of the anticyclone above and below the tropopause to the revised manuscript.

Regarding previous "Specific comments":

P3 L7-10: Thank you for the revision...However, I am sorry, but I cannot find this relation in the reference you have given! I see anomalous positive rainfall over India associated with La Nina (during summer) and also with additional La Nina conditions in the winter before (blue bars) in Fig. 1 c)-h) of Chakraborty, (2018). As this is not key to your analysis consider to cut this part regarding rainfall and ENSO...

P5 L3-5: Thank you for the clarification. I agree that the impact could be small and that other uncertainties might be more important. However, I still think that this relation (the equality) only holds during mixing time steps, i.e. time steps of tracer initialisation.

P9 L26-27: I think it would be beneficial to also relate to the findings of Pan et al. (2016) here!

P11 L5: You are releasing trajectories in a broad box not only within the anticyclone. Please consider my previous comment!

P11 L14: I do not think, that the studies by Randel et al. (2010) and Ploeger et al. (2017) make any claim to the homogeneity of the uplift. Please check if this is meant and stated in these references and revise accordingly.

P14 L6-8: Thank you for the clarification. Please consider to also add the reference to Vogel et al. (2015) in the revised manuscript.

Regarding previous "Minor suggestions/corrections":

To 1 and 2: I am sorry, I can not see any changes here. Please consider to include my previous suggestions, especially the second one.

To 3: consider to cut "the most" (cf. Conclusion of Mason and Anderson, 1963)

To 10: P13 L1 (R1): this should read "...transport of...." ("of" is missing)

To 12: switch "the" and "tropical"

References:

Chakraborty, A.: Preceding winter La Nina reduces Indian summer monsoon rainfall, Environmental Research Letters, 13, 054030, doi:10.1088/1748-9326/aabdd5, 2018.

Mason, R. B. and Anderson, C. E.: The development and decay of the 100-mb. summertime anticyclone over southern Asia, Mon. Weather Rev., 91, 3–12, doi:10.1175/1520-0493(1963)091<0003:TDADOT>2.3.CO;2, 1963.

Pan, L. L., Honomichl, S. B., Kinnison, D. E., Abalos, M., Randel, W. J., Bergman, J. W., and Bian, J.: Transport of chemical tracers from the boundary layer to stratosphere associated with the dynamics of the Asian summer monsoon, Journal of Geophysical Research: Atmospheres, 121, 14,159–14,174, doi:10.1002/2016JD025616, 2016.

Ploeger, F., Konopka, P., Walker, K., and Riese, M.: Quantifying pollution transport from the Asian monsoon anticyclone into the lower stratosphere, Atmos. Chem. Phys., 17, 7055–7066, doi:10.5194/acp-17-7055-2017, 2017.

Randel, W. J., Park, M., Emmons, L., Kinnison, D., Bernath, P., Walker, K. A., Boone, C., and Pumphrey, H.: Asian Monsoon Transport of Pollution to the Stratosphere, Science, 328, 611–613, doi:10.1126/science.1182274, 2010.

Vogel, B., Günther, G., Müller, R., Grooß, J.-U., and Riese, M.: Impact of different Asian source regions on the composition of the Asian monsoon anticyclone and of the extratropical lowermost stratosphere, Atmos. Chem. Phys., 15, 13 699–13 716, doi:10.5194/acp-15-13699-2015, 2015.

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RR by Anonymous Referee #3 (05 Feb 2019)

ED: Publish subject to minor revisions (review by editor) (26 Feb 2019) by Peter Haynes

AR by Bärbel Vogel on behalf of the Authors (12 Mar 2019) Author's response Manuscript

ED: Publish as is (18 Mar 2019) by Peter Haynes

AR by Bärbel Vogel on behalf of the Authors (25 Mar 2019) Manuscript

Short summary

We identified the transport pathways of air masses from the region of the Asian monsoon (e.g. pollution and greenhouse gases caused by increasing population and growing industries in Asia) into the lower stratosphere. Even small changes of the chemical composition of the lower stratosphere have an impact on surface climate (e.g. surface temperatures). Therefore, it is important to identify transport pathways to the stratosphere to allow potential environmental risks to be assessed.