Size-dependent particle activation properties in fog during the ParisFog 2012/13 field campaign

Hammer, E.; Gysel, M.; Roberts, G. C.; Elias, T.; Hofer, J.; Hoyle, C. R.; Bukowiecki, N.; Dupont, J.-C.; Burnet, F.; Baltensperger, U.; Weingartner, E.

doi:https://doi.org/10.5194/acp-14-10517-2014

Articles | Volume 14, issue 19

https://doi.org/10.5194/acp-14-10517-2014

© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-14-10517-2014

© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 14, issue 19

Research article

|

07 Oct 2014

Research article |

| 07 Oct 2014

Size-dependent particle activation properties in fog during the ParisFog 2012/13 field campaign

E. Hammer, M. Gysel, G. C. Roberts, T. Elias, J. Hofer, C. R. Hoyle, N. Bukowiecki, J.-C. Dupont, F. Burnet, U. Baltensperger, and E. Weingartner

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Final revised paper (published on 07 Oct 2014)
Supplement to the final revised paper
Preprint (discussion started on 08 Apr 2014)

Interactive discussion

Status: closed

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

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RC C2158: 'Referee comments for Hammer et al.', Anonymous Referee #1, 08 May 2014
- AC C6038: 'Response to Anonymous Referee #1', Emanuel Hammer, 19 Aug 2014
RC C2288: 'Review', Anonymous Referee #2, 11 May 2014
- AC C6042: 'Response to Anonymous Referee #2', Emanuel Hammer, 19 Aug 2014

Peer-review completion

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

AR by Emanuel Hammer on behalf of the Authors (19 Aug 2014) Author's response

ED: Referee Nomination & Report Request started (22 Aug 2014) by Veli-Matti Kerminen

RR by Anonymous Referee #2 (04 Sep 2014)

Suggestions for revision or reasons for rejection

In their response and in the revised paper, the authors write that larger particles in the area are more from the impinging background aerosol than local sources. They also say that these larger particles (roughly 300-500 nm) are more hygroscopic and are the preferred nuclei for the fog droplets. These statements appear to be mostly in response to my question about whether the fogs are influenced by the city’s emissions. The response as in new section 4.2.1 seems mostly reasonable and interesting. The new section 4.2.2 also seems reasonable.

In their responses, the authors say that a sharp change in kappa around 300 nm is implausible, yet they state in section 4.2.1 that Laborde et al. (2013) indicate these larger particles (apparently 265 nm and greater) are more hygroscopic than the smaller particles, and later that “the dominant contribution to particle mass and bulk composition comes from larger particles, which are mainly from the background aerosol.” This seems to me to be a little contradictory. If the authors agree, it should be modified accordingly.

In Figure 0.1 of their responses, the authors look at variations of diameters and kappas to justify the cut points, and I think this basic approach is fine, but they should also consider the 100% RH diameter of a dry 400-600 nm particle with a larger kappa value (e.g. 0.5).

I am pleased that the authors have clearly given very serious consideration to this problem. I am not convinced the authors are correct in describing ALL of the fog droplets as having occurred on “activated” particles, and I strongly suggest a caveat be added that some of the largest particles that acted as nuclei for the fog droplets may not have been truly activated. It can be surprising at how long it takes for some larger particles to activate, particularly in a slowly condensing system.

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ED: Reconsider after minor revisions (Editor review) (05 Sep 2014) by Veli-Matti Kerminen

AR by Emanuel Hammer on behalf of the Authors (05 Sep 2014) Author's response Manuscript

ED: Publish as is (08 Sep 2014) by Veli-Matti Kerminen

AR by Emanuel Hammer on behalf of the Authors (08 Sep 2014)

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