A refined method for calculating equivalent effective stratospheric chlorine

Engel, Andreas; Bönisch, Harald; Ostermöller, Jennifer; Chipperfield, Martyn P.; Dhomse, Sandip; Jöckel, Patrick

doi:https://doi.org/10.5194/acp-18-601-2018

Articles | Volume 18, issue 2

https://doi.org/10.5194/acp-18-601-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

The Modular Earth Submodel System (MESSy) (ACP/GMD inter-journal...

https://doi.org/10.5194/acp-18-601-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 18, issue 2

Research article

|

19 Jan 2018

Research article |

| 19 Jan 2018

A refined method for calculating equivalent effective stratospheric chlorine

Andreas Engel, Harald Bönisch, Jennifer Ostermöller, Martyn P. Chipperfield, Sandip Dhomse, and Patrick Jöckel

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Final revised paper (published on 19 Jan 2018)
Preprint (discussion started on 03 Jul 2017)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Review of Delayed Recovery of mid-latitude lower stratospheric Halogen Loading by Engel and co-workers', Anonymous Referee #1, 15 Aug 2017
RC2: 'Review of Engel et al', Anonymous Referee #2, 17 Aug 2017
RC3: 'Nice exercise', Anonymous Referee #3, 21 Aug 2017
RC4: 'Review', Anonymous Referee #4, 30 Aug 2017
AC1: 'Reliy to reviewers', Andreas Engel, 13 Nov 2017

Peer-review completion

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

AR by Andreas Engel on behalf of the Authors (14 Nov 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (14 Nov 2017) by Jan Kaiser

RR by Anonymous Referee #3 (27 Nov 2017)

RR by Anonymous Referee #2 (27 Nov 2017)

Suggestions for revision or reasons for rejection

The change in emphasis from the recovery date of ozone to the new method for calculating EESC is a good one and the inclusion of model comparisons also add to the robustness of the results. The authors have generally addressed all of my previous comments so I support publication with consideration of the additional specific comments below.

Specific comments (page numbers refer to the combined document with changes tracked):

Page 31, line 12: change “chemical” to “chemically”

Page 31, lines 18-25: I would be more specific when referring to the chemical lifetime here, and in general, as “local” or not. It’s clear enough that you mean local chemical lifetime in lines 17-18 but then in line 23 it’s not clear what you mean by “shorter lifetimes”.

Page 31, lines 27-28: “especially also of the” is awkward. I would suggest “…and on the path p it has taken, primarily the maximum path height (MPH), during transport.”

Page 43, line 19: change “which is” to “which was”. “Output from this model run is available from the years 1960-2016.”

Page 43, line 20: “as a function”

Page 43, line 20: Why are the model NH fractional release factors so much higher than observed? Is this significant?

Page 44, line 14: “on a fixed mean age level”

Page 44, line 16: “the year 2000”

Page 44, line 17: change “was” to “were”

Page 44, line 22: You should explain further what you mean and why you expect ozone mixing ratios to “follow” a pressure surface rather than a mean age surface in the future. Presumably the model output can verify this?

Page 45, line 9: replace “he” with “the”

Page 64, line 5: “The model simulation shown here used prescribed trace gas scenarios, sea surface temperatures and sea ice content.”

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ED: Publish subject to minor revisions (review by editor) (28 Nov 2017) by Jan Kaiser

AR by Andreas Engel on behalf of the Authors (30 Nov 2017) Author's response Manuscript

ED: Publish subject to technical corrections (04 Dec 2017) by Jan Kaiser

AR by Andreas Engel on behalf of the Authors (05 Dec 2017) Author's response Manuscript

Short summary

We present a new method to derive equivalent effective stratospheric chlorine (EESC), which is based on an improved formulation of the propagation of trends of species with chemical loss from the troposphere to the stratosphere. EESC calculated with the new method shows much better agreement with model-derived ESC. Based on this new formulation, we expect the halogen impact on midlatitude stratospheric ozone to return to 1980 values about 10 years later, then using the current formulation.