High occurrence of new particle formation events at the Maïdo high-altitude observatory (2150 m), Réunion (Indian Ocean)

Foucart, Brice; Sellegri, Karine; Tulet, Pierre; Rose, Clémence; Metzger, Jean-Marc; Picard, David

doi:https://doi.org/10.5194/acp-18-9243-2018

Articles | Volume 18, issue 13

Atmos. Chem. Phys., 18, 9243–9261, 2018

https://doi.org/10.5194/acp-18-9243-2018

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

Atmos. Chem. Phys., 18, 9243–9261, 2018

https://doi.org/10.5194/acp-18-9243-2018

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

Articles | Volume 18, issue 13

Research article 03 Jul 2018

Research article | 03 Jul 2018

High occurrence of new particle formation events at the Maïdo high-altitude observatory (2150 m), Réunion (Indian Ocean)

Brice Foucart et al.

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Final revised paper (published on 03 Jul 2018)
Preprint (discussion started on 27 Sep 2017)

Interactive discussion

Status: closed

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

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- Supplement

SC1: 'Events of ultrafine particle advection or new particle formation or a mountain circulation study?', Wolfgang Junkermann, 17 Oct 2017
- AC1: 'Response to the public short comment posted by Wolfgang Junkermann (SC1)', Brice Foucart, 08 Feb 2018
- AC4: 'Corrected files', Brice Foucart, 13 Feb 2018
RC1: 'Referee comment', Anonymous Referee #1, 08 Nov 2017
- RC2: 'Review', Anonymous Referee #2, 10 Nov 2017
  - AC3: 'Response to the anonymous reviewer comment (RC2)', Brice Foucart, 08 Feb 2018
  - AC6: 'Response to RC2 correct files', Brice Foucart, 13 Feb 2018
- AC2: 'Response to the anonymous reviewer comment (RC1)', Brice Foucart, 08 Feb 2018
- AC5: 'Response to RC1 correct files', Brice Foucart, 13 Feb 2018

Peer-review completion

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

AR by Brice Foucart on behalf of the Authors (02 Mar 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (12 Mar 2018) by Fangqun Yu

RR by Anonymous Referee #3 (09 Apr 2018)

Suggestions for revision or reasons for rejection

Finally I got a chance to go through the authors’ replies to the comments of previous reviewers as well as the revised manuscript. Sorry for the delay in submitting the review report.

I think that the authors have made good efforts in addressing the comments of two previous reviewers and the manuscript has been improved. The manuscript reported NPF measurements observed at a high altitude observatory over an Indian Ocean island in the Southern Hemisphere. The topic is suitable for ACP and the results shall be of interesting to the community. My additional comments, aimed to further improve the manuscript, are given below.

Major comments:
1. Lines 234-235. If boundary air convection to the size is a trigger for NPF events, why the cluster mode particles appeared half hour earlier than the BC increase? What about CO? Is such a delay common for all NPF events? Maybe it is worthwhile to provide similar figures for more days in the appendices.
2. Lines 263-268. It is interesting to see that NPF occurred on almost every day in April. Figure A4 is helpful. I strongly suggested that the authors present AIS data for both positive and negative ions in Figure A4. As I understand, ACP requires statement about the availability of the data used in the paper. Are these data available to the community after the publication of the manuscript?
3. Section 4.6. Are the monthly mean concentrations good indications of the air mass sources during the nucleation periods which typically last only a few hours each day? If not, BC and CO concentrations averaged during the nucleation periods may provide more insight about the relationship between NPF parameters and BC/CO concentrations.

Minor comments:
4. Line 17. “In 2014 and 2015”. Please provide the exact period (05/2014-12/2015) when the measurements were made.
5. Line 23. GR of 100 nm/hr is likely due to mixing and transport of air mass. Can you exclude the possibility that the derived growth rate of 100 nm/hr was due to mixing of air mass? If not, better not highlight this here in the abstract.
6. Line 72. Less than two year is not “multiyear”. Please be more accurate.
7. Line 129 and Line 141: “reached by the plume several times” is inconsistent with “47 daytime plume days”.
8. Is the PdF volcano eruptive? During the non-eruptive period, does it emit SO2?
9. Line 177: Figure 3 --> Figure 2?
10. Line 184: “ratio of event to non-event days” is inconsistent with what shown in Eq 1.
11. Line 207: “12 nm”--> “12-19 nm”.
12. Figure 3a. Since positive ions were also measured by AIS, the authors should provide these data as well.
13. Figure 3b. Please alight the time in axis with that of Figure 3a.
14. Line 244. Please given the exact size range of Aitken mode particles.
15. Line 248. “N30” should be “N<30”.

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ED: Publish subject to minor revisions (review by editor) (09 Apr 2018) by Fangqun Yu

AR by Brice Foucart on behalf of the Authors (19 Apr 2018) Author's response Manuscript

ED: Publish subject to minor revisions (review by editor) (08 May 2018) by Fangqun Yu

AR by Brice Foucart on behalf of the Authors (18 May 2018) Author's response Manuscript

ED: Publish as is (31 May 2018) by Fangqun Yu

Short summary

The main objective of this study is to reinforce the observations of new particle formation (NPF) events in the Southern Hemisphere and more particularly for a site that is both marine and at altitude, the Maïdo observatory (2150 m), on Réunion. We recorded a high annual NPF frequency of 65 % and we note that monthly averages show a bimodal variation. We estimate the intensity and the characteristics of the events and describe their seasonality by comparing them to other parameters.