Quantifying the vertical transport of CHBr3 and CH2Br2 over the western Pacific

Butler, Robyn; Palmer, Paul I.; Feng, Liang; Andrews, Stephen J.; Atlas, Elliot L.; Carpenter, Lucy J.; Donets, Valeria; Harris, Neil R. P.; Montzka, Stephen A.; Pan, Laura L.; Salawitch, Ross J.; Schauffler, Sue M.

doi:https://doi.org/10.5194/acp-18-13135-2018

Articles | Volume 18, issue 17

Atmos. Chem. Phys., 18, 13135–13153, 2018

https://doi.org/10.5194/acp-18-13135-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

Atmos. Chem. Phys., 18, 13135–13153, 2018

https://doi.org/10.5194/acp-18-13135-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 18, issue 17

Research article 12 Sep 2018

Research article | 12 Sep 2018

Quantifying the vertical transport of CHBr₃ and CH₂Br₂ over the western Pacific

Robyn Butler et al.

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Final revised paper (published on 12 Sep 2018)
Preprint (discussion started on 29 Nov 2016)

Interactive discussion

Status: closed

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

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RC1: 'Review of “Quantifying the vertical transport of CHBr3 and CH2Br2 over the Western Pacific”', Anonymous Referee #2, 28 Dec 2016
RC2: 'Review of Butler et al.', Anonymous Referee #3, 06 Jan 2017
RC3: 'Review of Butler et al. 2016', Qing Liang, 12 Jan 2017
AC1: 'Responses to all Reviewers', Robyn Butler, 15 Aug 2017

Peer-review completion

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

AR by Robyn Butler on behalf of the Authors (06 Sep 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (11 Sep 2017) by Rolf Müller

RR by Anonymous Referee #2 (05 Oct 2017)

Suggestions for revision or reasons for rejection

Many improvements have been achieved since the 1st round of review. The authors have
properly addressed the specific issues I raised before (Specific comments I, II and III), being the
most important the correction of including an independent land tracer for VSL emissions.
However, I still find that the description and discussion of the results can be greatly improved,
and that the main results found can be written in a more rigorous fashion. Indeed, my general
concern during 1 st round of review was: “ ... and most importantly, I found many of the analysis
and discussions given in Sections 4 (Results) and 5 (Discussions and Concluding remarks) very
vague and/or requiring stronger evidence that supports them. I suggest being more specific
and formal on the explanation of the specific statements highlighted in this review”; which was
not answered nor commented in the response letter.

I found that many of my original issues raised in the review were properly answered in the
response letter. But when I read the 2nd draft, those answers were not so clearly described or
justified in the manuscript text. For example, the answer letter points out that (P2) “... e.g.,
coastal emissions play a larger role at higher altitudes.” or (P7) “...The total tracer is based on a
12-month spin up from the emission scenario with the ‘total ocean’ emissions included. The
VSLS VMR that is not represented by the tagged tracers will be attributed to ‘background’ VMR
from the spin up file, which represents the VMR from before the campaign. We have clarified
this in the method and discussion sections”. I could not find those (or equivalent) sentences in
the manuscript. Please, be sure to include all comments from the response letter into the
manuscript.

As I previously mentioned, “I found the study very interesting and of relevance for ACP”, but I
believe redaction/quality improvements can be achieved before final publication. Those
should be oriented to avoid using misleading interpretations if individual sentences are
extracted from the paragraph (P1, “In the absence of reliable ocean emission estimates,...“; or
P5, “We chose to use Liang et al. (2010) because it has a consistent bias for CHBr3 and
CH2Br2.”) and to justify the contributions of other factors/scenarios not explicitly considered
in the tagged experiments performed in this work (P7, “Larger differences in the correlations
for CH2Br2 is likely due to differences in the sampled air masses that have originated far
upwind.”). Additionally, the manuscript would benefit of a comprehensive discussion on how
the Butler et al results relate to previously published papers already in the literature (mainly
those performed in the same region of study). In the attached file I point out to the main
phrases/sentences in the text were I found some ambiguity or confusion that should be
improved.

Referee Report: PDF

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RR by Anonymous Referee #3 (12 Oct 2017)

ED: Publish subject to minor revisions (review by editor) (20 Oct 2017) by Rolf Müller

AR by Paul Palmer on behalf of the Authors (02 Jul 2018) Author's response Manuscript

ED: Publish subject to technical corrections (04 Jul 2018) by Rolf Müller

AR by Paul Palmer on behalf of the Authors (25 Jul 2018) Author's response Manuscript

Short summary

Natural sources of short-lived bromoform and dibromomethane are important for determining the inorganic bromine budget in the stratosphere that drives ozone loss. Two new modelling techniques describe how different geographical source regions influence their atmospheric variability over the western Pacific. We find that it is driven primarily by open ocean sources, and we use atmospheric observations to help estimate their contributions to the upper tropospheric inorganic bromine budget.