Radiative forcing and climate metrics for ozone precursor emissions: the impact of multi-model averaging

MacIntosh, C. R.; Shine, K. P.; Collins, W. J.

doi:https://doi.org/10.5194/acp-15-3957-2015

Articles | Volume 15, issue 7

https://doi.org/10.5194/acp-15-3957-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-15-3957-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 15, issue 7

Research article

|

15 Apr 2015

Research article |

| 15 Apr 2015

Radiative forcing and climate metrics for ozone precursor emissions: the impact of multi-model averaging

C. R. MacIntosh, K. P. Shine, and W. J. Collins

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Final revised paper (published on 15 Apr 2015)
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Preprint (discussion started on 29 Oct 2014)
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Interactive discussion

Status: closed

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

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RC C9714: 'Comment on "Radiative forcing and climate metrics for ozone precursor emissions: the impact of multi-model averaging" by MacIntosh et al.', Anonymous Referee #1, 29 Nov 2014
- AC C12335: 'Response to Reviewer 1', Claire MacIntosh, 19 Feb 2015
RC C11049: 'Assessing the ensembling – has our penchant for averaging models gone amuck?', Anonymous Referee #2, 10 Jan 2015
- AC C12336: 'Response to Reviewer 2', Claire MacIntosh, 19 Feb 2015

Peer-review completion

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

AR by Claire MacIntosh on behalf of the Authors (03 Mar 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (06 Mar 2015) by Jason West

RR by Anonymous Referee #1 (17 Mar 2015)

Suggestions for revision or reasons for rejection

The readability of the manuscript has been substantially improved after the revision; now it is much more focused and is clearly structured. I recommend that it is published after some technical corrections. I suggest the authors perform a thorough proof-reading of the manuscript, especially paying attention to the units of CH4 RFs in figures and tables. I list some issues below.

P3, line -9 “H that is under investigation” – can you explain what “H” means here? You should change it to italic font and put a “,” after if it symbolizes “the time horizon”.
P5, line 2 missing “)”
P7, line -5 “These lifetimes include loss terms such as those due to soil processes;” – they should also include stratospheric loss (Fiore et al. 2009).
P10, line 3 “For the Fry-method subset, the metrics must be constructed more carefully.” – relative to what? This sentence is a bit empty and it is not clear to me how it connects to the following text.
In figure 3:
1) The wrong unit of RF in the figure – should be “W m-2”. This should also be corrected in the caption.
2) In caption, it reads like the CH4 RF is also normalised which I take it is not. So it needs some rephrasing.
P13, line 10, I suggest it would be more appropriate to say “anti-correlation”.
In section 4 “Radiative forcing” there is only one subsection 4.1. Maybe you could turn the first part into a subsection to keep the structure in balance.
In section 4, the unit of CH4 RF was first mentioned in W m-2 (also shown in Figure 3) but subsequently you cite these numbers in units of mW m-2 from the literature. It is really minor but it would be good practice to be consistent. I suggest to use mW m-2 throughout which is in line with the units used in other work.
Figure 4, the units of RF CH4 are not consistent in the figure (W m-2) and in the caption (mW m-2). Please correct. Why don’t you use mW m-2 throughout?
Table 3, no units specified for RF CH4 in the table caption.

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ED: Publish subject to technical corrections (25 Mar 2015) by Jason West

AR by Claire MacIntosh on behalf of the Authors (01 Apr 2015) Author's response Manuscript

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Short summary

This study examines quantitatively the impact of methodological choices, in particular of averaging of multi-model ensembles, on climate metrics for ozone precursors. Estimates of the standard deviation of radiative forcing (RF), global warming and temperature potential (GWP, GTP) from ensemble-mean input fields generally overestimate the true value. The multi-model average fields are appropriate for calculating mean metrics, but are not a reliable method for calculating the uncertainty.