Effect of vehicular traffic, remote sources and new particle formation on the activation properties of cloud condensation nuclei in the megacity of São Paulo, Brazil

Souto-Oliveira, Carlos Eduardo; Andrade, Maria de Fátima; Kumar, Prashant; Lopes, Fábio Juliano da Silva; Babinski, Marly; Landulfo, Eduardo

doi:https://doi.org/10.5194/acp-16-14635-2016

Articles | Volume 16, issue 22

Atmos. Chem. Phys., 16, 14635–14656, 2016

https://doi.org/10.5194/acp-16-14635-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Atmos. Chem. Phys., 16, 14635–14656, 2016

https://doi.org/10.5194/acp-16-14635-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 16, issue 22

Research article 24 Nov 2016

Research article | 24 Nov 2016

Effect of vehicular traffic, remote sources and new particle formation on the activation properties of cloud condensation nuclei in the megacity of São Paulo, Brazil

Carlos Eduardo Souto-Oliveira et al.

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Final revised paper (published on 24 Nov 2016)
Supplement to the final revised paper
Preprint (discussion started on 21 Apr 2016)
Supplement to the preprint

Interactive discussion

Status: closed

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

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RC1: 'referee comments', Anonymous Referee #1, 11 Jun 2016
- AC1: 'Reply to comments of Anonymous Referee # 1.', Carlos Oliveira, 17 Aug 2016
RC2: 'Referee comment', Anonymous Referee #2, 06 Jul 2016
- AC2: 'Reply to comments of Anonymous Referee # 2.', Carlos Oliveira, 17 Aug 2016

Peer-review completion

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

AR by Carlos Oliveira on behalf of the Authors (17 Aug 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (18 Aug 2016) by Veli-Matti Kerminen

RR by Anonymous Referee #1 (01 Sep 2016)

Suggestions for revision or reasons for rejection

1. Abstract and Conclusion sections: "Our results show that particulate matter from local pollution sources, mainly local road traffic emissions, has a greater effect on CCN activation parameters than those from remote sources."
"In summary, local pollution sources, represented mainly by vehicular traffic emissions, had greater negative effects on activation parameters than did remote sources."

According to the authors, local sources are even not able to be discriminated in this study. So how can they conclude local sources had greater negative effect on CCN activation? Moreover, in figure 9, 10, 11 and 12, there are no AR or Dact data about local sources at all. How can they make any conclusion about local source effect? This is my major concern.

3. page 17 line 20-22,
"As can be seen in Fig.12c, diurnal periods with NPF showed lower AR values than did biomassburning and non-event days. However, AR values were similar among nights after NPF with those non-event and sea salt influence nights and also biomass burning after NPF events."
---In daytime NPF AR is about 0.05 lower than Biomass burning and non-event. Comparing with this, I would say AR in the night after NPF is also lower (not similar!) than those non-event and sea salt influence nights. Or I would say AR in all nighttime classes were just slightly different.

4. page 17 line 23-25
"Lower AR for nocturnal periods with sea-salt influence after NPF can be attributed to smaller particle size, whereas sea-salt events in these nocturnal periods occurred after low-O3 NPF events (on days 7 and 8)."
This sentence does not make sense at all. AR for nocturnal periods with seasalt+NPF is not low. Instead, it is the second highest among all.

5. page 17 line 16,
"Another important information is the variability in the volume of vehicular traffic, asestimated from the meanNOx and CO values(Fig. 12b), which was previouslyassociated with decreasedCCN activation."
Fig 12 b does not show any information about traffic volume or its variability.

6. I suggest to use daytime and nighttime, which are more commonly used in the literature, to replace diurnal and nocturnal throughout the manuscript.
7. I suggest to shorten section 2.6 and 3.4

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ED: Reconsider after major revisions (02 Sep 2016) by Veli-Matti Kerminen

AR by Carlos Oliveira on behalf of the Authors (25 Sep 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (28 Sep 2016) by Veli-Matti Kerminen

RR by Anonymous Referee #1 (30 Oct 2016)

ED: Reconsider after minor revisions (Editor review) (31 Oct 2016) by Veli-Matti Kerminen

AR by Carlos Oliveira on behalf of the Authors (02 Nov 2016) Author's response Manuscript

ED: Publish as is (02 Nov 2016) by Veli-Matti Kerminen

Short summary

The Metropolitan Area of São Paulo is the biggest megacity of South America, with over 20 million inhabitants. In recent years, the region has been facing a modification in rain patterns. In this study, we evaluated the effects of local and remote sources of air pollution on cloud-condensation nuclei activation properties. Our results showed that the local vehicular traffic emission products presented more negative effects on cloud-condensation nuclei activation than the remote sources.