The impact of biogenic, anthropogenic, and biomass burning volatile organic compound emissions on regional and seasonal variations in secondary organic aerosol

Kelly, Jamie M.; Doherty, Ruth M.; O'Connor, Fiona M.; Mann, Graham W.

doi:https://doi.org/10.5194/acp-18-7393-2018

Articles | Volume 18, issue 10

https://doi.org/10.5194/acp-18-7393-2018

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

https://doi.org/10.5194/acp-18-7393-2018

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

Articles | Volume 18, issue 10

Research article

|

28 May 2018

Research article |

| 28 May 2018

The impact of biogenic, anthropogenic, and biomass burning volatile organic compound emissions on regional and seasonal variations in secondary organic aerosol

Jamie M. Kelly, Ruth M. Doherty, Fiona M. O'Connor, and Graham W. Mann

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Final revised paper (published on 28 May 2018)
Preprint (discussion started on 07 Nov 2017)

Interactive discussion

Status: closed

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

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RC1: 'Review of Kelly et al.', Anonymous Referee #1, 07 Dec 2017
RC2: 'Review of Kelly et al.', Anonymous Referee #2, 18 Feb 2018
AC1: 'Author responses to reviewers' comments', Jamie Kelly, 27 Mar 2018

Peer-review completion

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

AR by Jamie Kelly on behalf of the Authors (27 Mar 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (02 Apr 2018) by Kostas Tsigaridis

RR by Anonymous Referee #1 (04 Apr 2018)

RR by Anonymous Referee #2 (17 Apr 2018)

Suggestions for revision or reasons for rejection

I generally agree with the author’s stance on most of my comments and I think the change in the framing of the problem – one of focusing on the SOA formation from VOCs – responds to my major concern with this manuscript. There are however a few things I would like to point out from the response that caught my attention.

1. For the response on comment #1, I don’t agree with the simple explanation added to the manuscript to justify the use of a non-volatile POA that ‘there is evidence for both semi-volatile and non-volatile OA’. The issue of volatility is nuanced and should be discussed accordingly. For instance, source measurements of combustion POA performed at different dilutions (e.g., May et al., 2013a,b,c) and thermodenuder measurements of laboratory-generated (e.g., Huffman et al., 2009a) and field OA (e.g., Huffman et al., 2009b) clearly demonstrate that OA is semi-volatile with some fraction of non-volatile material. However, certain experiments with model SOA systems exhibit delays in evaporation that could be a result of diffusion-linked limitations to evaporation (e.g., Vaden et al., 2009). Simply stating that there is evidence for both and then treating the POA as non-volatile suggests that the weight of the literature points towards POA being more non-volatile, which is definitely not the case.

2. The response in comment #2 makes it sound that we do not know a lot about the differences in VOC reaction rates, SOA mass yields, and speciation of anthropogenic and biomass burning emissions. I would argue that a lot has been understood over the past decade (e.g., motor vehicle VOC = May et al., 2014; Zhao et al., 2015; Zhao et al., 2016, biomass burning = Stockwell et al., 2015; Hatch et al., 2017) but that there is still a lot more to learn. Also, I disagree with some of the inferences made from the literature. For instance, the differences in SOA mass yields between different aromatic compounds can be explained if the aromatics are split into low and high yield categories (Odum et al., 1996). NOx effects on SOA formation from aromatics can be modeled through a competition of the RO2 radical with NO and HO2 (Henze et al., 2008). Furthermore, for a model such as that used in this work adding model species can be computationally expensive and need to be kept to a minimum. However, their reactivity and SOA mass yield could be informed by a weighted average of the mixture of species used to represent the model species.

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ED: Publish subject to minor revisions (review by editor) (17 Apr 2018) by Kostas Tsigaridis

AR by Jamie Kelly on behalf of the Authors (24 Apr 2018)

ED: Publish as is (25 Apr 2018) by Kostas Tsigaridis

AR by Jamie Kelly on behalf of the Authors (01 May 2018)

Short summary

The global secondary organic aerosol (SOA) budget is highly uncertain with global models typically underpredicting observed SOA concentrations. Using a global chemistry-climate model, the impacts of biogenic, anthropogenic, and biomass burning VOC emissions on the global SOA budget and model agreement with observed SOA concentrations are quantified.