Influence of intense secondary aerosol formation and long-range transport on aerosol chemistry and properties in the Seoul Metropolitan Area during spring time: results from KORUS-AQ

Kim, Hwajin; Zhang, Qi; Heo, Jongbae

doi:https://doi.org/10.5194/acp-18-7149-2018

Articles | Volume 18, issue 10

https://doi.org/10.5194/acp-18-7149-2018

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

https://doi.org/10.5194/acp-18-7149-2018

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

Articles | Volume 18, issue 10

Research article

|

24 May 2018

Research article |

| 24 May 2018

Influence of intense secondary aerosol formation and long-range transport on aerosol chemistry and properties in the Seoul Metropolitan Area during spring time: results from KORUS-AQ

Hwajin Kim, Qi Zhang, and Jongbae Heo

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Final revised paper (published on 24 May 2018)
Supplement to the final revised paper
Preprint (discussion started on 08 Nov 2017)
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Interactive discussion

Status: closed

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

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RC1: 'Review', Anonymous Referee #1, 06 Dec 2017
- AC1: 'Author comment1(AC)', Hwajin Kim, 02 Feb 2018
RC2: 'Referee Comments', Anonymous Referee #2, 07 Dec 2017
- AC2: 'Author comment2(AC)', Hwajin Kim, 02 Feb 2018

Peer-review completion

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

AR by Hwajin Kim on behalf of the Authors (02 Feb 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (06 Feb 2018) by Chak K. Chan

RR by Anonymous Referee #2 (11 Feb 2018)

RR by Anonymous Referee #1 (15 Feb 2018)

Suggestions for revision or reasons for rejection

I thank the authors for taking on board my comments, however I do not feel that they have addressed all of the comments I raised.

The issue regarding COA is still not resolved. As I was at pains to point out, similarity with previously published mass spectra does not in itself prove it is related to cooking as the peaks are common to various long-chain fatty acids that could have other sources. The discussion regarding correlation with tracers adds nothing; all this does is prove that the factor contributes the most variance to those markers but as they are not unique to cooking, this does not prove that cooking was responsible. I would disagree that the diurnal cycle is in any way consistent with previously reported urban studies and it is very misleading to say it undergoes an 'enhancement' at 19:00 when the peak is clearly later at 22:00. Furthermore, the slow decrease in signal over the subsequent hours is very inconsistent with previously published cooking profiles, which typically drop off within only an hour or two of the initial peak. As such, I still doubt that this can be associated with cooking and I request that the the authors add the caveats I originally requested.

I feel that the authors misunderstood my comment about the fSO4; using temperature data alone, it should be possible to estimate the OH concentration based on established rate constants for the SO2+OH pathway to H2SO4 production. By comparing the inferred OH concentrations to previously reported urban concentrations, one could easily check whether this narrative is plausible.

It is simply not correct to infer that particles are pH neutral based on an observation of ion balance (as reported in S10) because given how strong the solution strengths are, only very small deviations from this can vastly alter the pH in haze droplets. Estimating aerosol pH requires explicit knowledge of the particle and gas phase ion concentrations, the water content of the particles and the invocation of a thermodynamic model such as e-AIM. Also, while the particles may begin as neutral, any formation of H2SO4 will immediately suppress the pH, so the NO2 and O3 pathways may potentially become self-limiting in haze particles unless there is an abundance of gas phase NH3 to compensate. The text should be modified to reflect these details.

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ED: Reconsider after major revisions (21 Feb 2018) by Chak K. Chan

AR by Hwajin Kim on behalf of the Authors (04 Apr 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (10 Apr 2018) by Chak K. Chan

RR by Anonymous Referee #1 (10 Apr 2018)

RR by Anonymous Referee #2 (15 Apr 2018)

RR by Anonymous Referee #3 (25 Apr 2018)

ED: Publish subject to minor revisions (review by editor) (30 Apr 2018) by Chak K. Chan

AR by Hwajin Kim on behalf of the Authors (03 May 2018) Author's response Manuscript

ED: Publish as is (05 May 2018) by Chak K. Chan

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Short summary

Aerosol chemistry, sources and processes driving the observed temporal and diurnal variations of PM were studied in the Seoul Metropolitan Area (SMA) during spring 2016. An in-depth analysis of the data uncovered that air quality in SMA was influenced strongly by secondary aerosol formation. Also, it was found that the haze episode during spring was mainly caused by a combination of both regional and local factors, which is different from the winter haze mainly caused by intense local sources.