Maximizing ozone signals among chemical, meteorological, and climatological variability

Brown-Steiner, Benjamin; Selin, Noelle E.; Prinn, Ronald G.; Monier, Erwan; Tilmes, Simone; Emmons, Louisa; Garcia-Menendez, Fernando

doi:https://doi.org/10.5194/acp-18-8373-2018

Articles | Volume 18, issue 11

https://doi.org/10.5194/acp-18-8373-2018

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

https://doi.org/10.5194/acp-18-8373-2018

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

Articles | Volume 18, issue 11

Research article

|

15 Jun 2018

Research article |

| 15 Jun 2018

Maximizing ozone signals among chemical, meteorological, and climatological variability

Benjamin Brown-Steiner, Noelle E. Selin, Ronald G. Prinn, Erwan Monier, Simone Tilmes, Louisa Emmons, and Fernando Garcia-Menendez

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Final revised paper (published on 15 Jun 2018)
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Preprint (discussion started on 28 Nov 2017)
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Interactive discussion

Status: closed

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

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RC1: 'Review of acp-2017-954', Anonymous Referee #1, 13 Dec 2017
RC2: 'Review of acp-2017-954', Anonymous Referee #2, 15 Feb 2018
AC1: 'Brown-Steiner Response to Referees', Benjamin Brown-Steiner, 29 Mar 2018

Peer-review completion

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

AR by Anna Wenzel on behalf of the Authors (03 Apr 2018) Author's response

ED: Referee Nomination & Report Request started (05 Apr 2018) by Jayanarayanan Kuttippurath

RR by Anonymous Referee #1 (13 Apr 2018)

RR by Anonymous Referee #2 (07 May 2018)

Suggestions for revision or reasons for rejection

Review of "Maximizing ozone signals among chemical, meteorological, and climatological variability" by B. Brown-Steiner et al. (acp-2017-954)

General Comments

The revisions to this manuscript addressed many of the concerns expressed in my original review, and helped to improve significantly the quality of the manuscript. The framework of a "sliding-scale" view of ozone variability is a particularly innovative new contribution from this work. However, I have a few remaining concerns about the manuscript, which I list below. These concerns could be addressed through minor revisions and would not require new simulations or new substantive analyses.

Define better what is meant by "ozone signals". The intended meaning of this term is never defined. Throughout most of the paper, the emphasis is on the use of spatial and temporal averaging to decrease the meteorological variability. In this case, a robust estimate of the mean ozone mixing ratio (averaged appropriately) is the 'signal' that can be detected within a specified error tolerance. While this is one important type of ozone signal, the Abstract and Introduction also discuss ozone change 'signals', resulting for instance from emissions change or climate change, as opposed to meteorological variability. This type of ozone 'signal' is not discussed adequately in the paper. For instance, how can a forced trend in ozone concentrations be detected? Given the recommendations of 10-15 year averaging period, would this suggest the need for a 10-15 year average before an assumed instantaneous change in emissions, followed by a 10-15 year average afterwards? Presumably, the magnitude of the shift relative to the magnitude of the internal meteorological variability would be relevant to the required averaging period. Some discussion of such issues would greatly improve the usefulness and applicability of the methodologies in this paper.

Minor Comments

Abstract, lines 43-46 -- Another possible reason for considering a shorter averaging period might be if a particularly large change (e.g., from rapid emissions reductions) were detected. If this change were large relative to the meteorological variability, a shorter averaging window could be used.

Section 2.1, lines 193-195 -- Sentence fragment. Revise.

Section 4, line 447 -- "three" --> "four"

Section 5, lines 538-540 -- Clarify what is meant by "the resultant magnitude of these changes" and "these changes and signals".

Section 5, line 551 -- "out" --> "our"

Section 5, line 558 -- Clarify the timescale over which the ozone variations of +/- 10-20 ppbv occur. Interannual variability of summer mean?

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ED: Publish subject to minor revisions (review by editor) (09 May 2018) by Jayanarayanan Kuttippurath

AR by Benjamin Brown-Steiner on behalf of the Authors (19 May 2018) Author's response Manuscript

ED: Publish as is (26 May 2018) by Jayanarayanan Kuttippurath

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Short summary

Detecting signals in observations and simulations of atmospheric chemistry is difficult due to the underlying variability in the chemistry, meteorology, and climatology. Here we examine the scale dependence of ozone variability and explore strategies for reducing or averaging this variability and thereby enhancing ozone signal detection capabilities. We find that 10–15 years of temporal averaging, and some level of spatial averaging, reduces the risk of overconfidence in ozone signals.