Dynamic and timing properties of new aerosol particle formation and consecutive growth events

Salma, Imre; Németh, Zoltán

doi:https://doi.org/10.5194/acp-19-5835-2019

Articles | Volume 19, issue 9

https://doi.org/10.5194/acp-19-5835-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-19-5835-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 9

Research article

|

03 May 2019

Research article |

| 03 May 2019

Dynamic and timing properties of new aerosol particle formation and consecutive growth events

Imre Salma and Zoltán Németh

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Final revised paper (published on 03 May 2019)
Supplement to the final revised paper
Preprint (discussion started on 01 Oct 2018)
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: 'Review', Anonymous Referee #3, 14 Jan 2019
- AC1: 'Response to Referee #3', Imre SALMA, 07 Feb 2019
RC2: 'review Salma et al', Anonymous Referee #4, 14 Jan 2019
- AC2: 'Response to Referee #4', Imre SALMA, 07 Feb 2019

Peer-review completion

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

AR by Imre Salma on behalf of the Authors (07 Feb 2019)

ED: Referee Nomination & Report Request started (08 Feb 2019) by Xavier Querol

RR by Anonymous Referee #3 (18 Feb 2019)

Suggestions for revision or reasons for rejection

The authors have improved the manuscript and deleted some critical statements.
I still think the title is not appropriate. What are the consequences of an average J6 of 4.6 cm-3 s-1 and an average GR of 7.3 nm h-1? The manuscript provides a multi-year statistical analysis of dynamic properties of new aerosol formation and growth events as well as gas phase compounds and looks for relations between these parameters. The manuscript does not provide much beyond this.
The authors claim” daily activity time pattern of inhabitants determine many atmospheric sources and important processes”. However, they choose UTC+1 throughout the year to characterize the starting time of NPF. In addition, Figure 4 clearly shows that radiation has an important impact on the particle formation and growth process. All this is contradictory to their statement. With their approach they find that “nucleation ordinarily starts at 09:15 UTC+1”. I doubt that this result is very helpful for e.g. modelers, if they know that nucleation can happen sometime between 6 – 12 a.m. Of interest would be some information on the underlying process/drivers.

I agree to the publication of the manuscript after some minor revisions as outlined below.

Line 266-270: this is an incomplete sentence. Probably you need to delete “and which”
Line 274-275: These explain….. This sentence is not clear.
Line 318-319: the factor could distort the dynamic relationships …. It could also be that neglecting this factor leads to a bias. It can be either way.
Line 506-508: this sentence is unclear. Why should there be a seasonal bias? I assume you compare event and non-event days per month. Otherwise it does not make sense.
Line 508: I do not see a seasonal cycle for CS.
Line 526: “uncertainty”, should this not be variability?
Line 542: “higher biogenic emissions and typically stronger photochemistry are expected” higher photochemical activity also enhances formation of nucleating species from anthropogenic VOCs. It must not necessarily be biogenic species.
Line 544: “nothing extra that would suppress the dynamical properties”. This is not fully correct. Higher T in summer leads to higher vapor pressure and decreases supersaturation. This decreases nucleation and growth rates.
Line 666: In line 467 you estimate H2SO4 to 5E05 cm-3. 12.3% of growth by H2SO4 results in about 1 nm/h. This would need about 5E07 H2SO4. How do you explain this discrepancy of 2 orders of magnitude?
Line 668: what do you mean with “excess”? “formation of H2SO4 is likely governed by photochemical conditions”: what other processes than photochemical production could do it under the given urban conditions?
Line 794: replace cloud by CLOUD. You need to say what this is.
The writing of the text is still quite complicated and not so concise. English needs substantial improvement yet.

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RR by Anonymous Referee #5 (13 Mar 2019)

RR by Anonymous Referee #6 (19 Mar 2019)

Suggestions for revision or reasons for rejection

This manuscript focuses on the study of new particle formation events in Budapest during a 6 year period by using a DMPS (6-1000 nm). Formation rate and growth rates were calculated based in different assumptions and estimations that may yield large uncertainties.
My first concern is that the title does not reflect the aim of the study. Actually, the consequences of the dynamic and timing of NPF are not investigated. The objectives stated in the introduction section are not really addressed in the manuscript.
Results obtained do no provide new findings respect previous studies in the area, except for a longer dataset. Are the results obtained here comparable with those obtained in other areas? The methodological approach is not new and presents some limitations. The low size range of 6nm is indeed a limitation of the study of the new particle formation events (NPF). The statically treatment can also be improved.
However, I consider that the long data set presented is worthy to be published. To this end, the next major changes are necessary:
The title must be changed reflecting the real scope of the study.
Conclusions should be stated taking into account the limitations of the method employed. Some of sentences stated in the abstract (“The 15 NPF and growth events produce 4.6 aerosol particles with a diameter of 6 nm in 1 cm3 of air in 16 1 s…”) and in the conclusion sections must be modified taking into account the limitations of the methodology and the scope of the study.
The conclusion section does not exactly reflect the results obtained during this study. Thus, the present study did not provide information about effect of NPF in urban climate and health risk (l774-776). Cited form text (L792-793): “the present research…provided evidence that some important chemical players in the NPF and growth events are still missing”. This cannot be considered as a conclusion obtained in this paper. The methodology used does not permit to identify key chemical players because the methods used are not the most adequate to this end.
The statically treatment can be improved. The analysis should be performed for both the NPF and non-NPF events. Thus, in Section 4-2 and Figure 2, the analysis of the monthly evolution is limited to the NPF formation events. It should also be performed for the non-NPF events. A figure about daily evolution of NPF events, and other variables, could help for interpretation.
English grammar is good, but sentences are quite long and, frequently do no provide useful information. The length of the text must be shorted (27 pages, without references with only 3 figures and 3 tables).
Section 4-2 and Figure 2: It is surprising the monthly evolution of NOx and SO2. Information about DL for SO2 should be provided. Monthly and daily evolution for both NPF and non-NPF events would also provide info about it.
Section 4.4. As it is do not provide very useful information.
Minor.
Methodology: sampling performed at two sites with different inlet configuration; were the particle loses corrected?
Table 1: add annual mean concentrations in Table 1, and simplify the description in the beginning of section 4.
Line 341: define range for UF and N (UF/N)
Figure captions: can be simplified; too long
Page 14; lines 439-441: This statement is not directly deduced from the observations.
Figure 2: scale for NOx and SO2
Page 26. Lines 774-776: it cannot be inferred from the cited example that NPF can affect urban climate and health risk
Page26; rows 792-793: the present research does not permit to identify key chemical players because the methods used e not the most adequate to do it.

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ED: Reconsider after major revisions (21 Mar 2019) by Xavier Querol

AR by Imre Salma on behalf of the Authors (01 Apr 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (09 Apr 2019) by Xavier Querol

RR by Anonymous Referee #3 (10 Apr 2019)

RR by Anonymous Referee #6 (21 Apr 2019)

ED: Publish subject to technical corrections (22 Apr 2019) by Xavier Querol

AR by Imre Salma on behalf of the Authors (23 Apr 2019) Author's response Manuscript

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Short summary

Condensing atmospheric chemical species and/or their processes in the city centre seem to contribute equally to new particle formation and particle growth. In the near-city background, however, chemical compounds and their processes power particle growth more than particle formation. There is much indirect evidence that chemical species other than H₂SO₄ largely influence the particle growth and possibly the atmosphere.