Natural new particle formation at the coastal Antarctic site Neumayer

Weller, R.; Schmidt, K.; Teinilä, K.; Hillamo, R.

doi:https://doi.org/10.5194/acp-15-11399-2015

Articles | Volume 15, issue 19

https://doi.org/10.5194/acp-15-11399-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-15-11399-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 15, issue 19

Research article

|

15 Oct 2015

Research article |

| 15 Oct 2015

Natural new particle formation at the coastal Antarctic site Neumayer

R. Weller, K. Schmidt, K. Teinilä, and R. Hillamo

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Final revised paper (published on 15 Oct 2015)
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Preprint (discussion started on 11 Jun 2015)
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Interactive discussion

Status: closed

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

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RC C4699: 'Weller et al "NPF in Antarctica": Review comments', Anonymous Referee #2, 09 Jul 2015
- AC C5775: 'Author comment referee #2 acp-2015-242', Rolf Weller, 10 Aug 2015
RC C4802: 'Weller et al. Referee Comment', Anonymous Referee #1, 13 Jul 2015
- AC C5779: 'Author comment on referee #1 acp-2015-242', Rolf Weller, 10 Aug 2015

Peer-review completion

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

AR by Rolf Weller on behalf of the Authors (14 Aug 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (16 Aug 2015) by Fangqun Yu

RR by Anonymous Referee #2 (21 Sep 2015)

RR by Anonymous Referee #3 (28 Sep 2015)

Suggestions for revision or reasons for rejection

The authors have addressed most of comments raised in the discussion phase. I recommend that the authors address/clarify the following comments/points to further improve the manuscript.
1. Lines 21-22. I think that you mean that the particles did not grow to CCN within a day or two. How do you know these particles, after transferred to elsewhere, will not continue to grow to CCN sizes? Also the meaning of “Thus in the main,” is not very clear and may need to be rephrased.
2. Line 121. Could you provide an estimation of the “enhanced uncertainties”?
3. Line 222. Appreciate the link to the data. I only found the SMPS data there. I encourage the authors to provide the time series of “concurrently measured total CP concentrations, meteorological parameters, and the ionic composition of the bulk aerosol” as well (in addition to the figures given in the supplementary material).
4. Lines 270-271. It appears to me that the conclusion of this sentence is not consistent with previous discussions (Lines 261-269). You mentioned that “During NPF events trajectories mainly stayed below 1500 m above ground for the last 48 hours before arrival at NM” and “Only for the NPF event at 16 March 2012 air masses clearly descended from the free troposphere”. If the air masses for ALL the events EXCEPT ONE were from recent MBL, your observations did indicate “a pronounced impact of recent MBL air advection”. Your conclusion should reflect this.
5. Equation (3). What is typical water content of nucleation mode particles? What’s the contribution of water uptake on the growth rates?
6. Equ. (3) and Table 2. If I plug the numbers you gave into Equ. (3), I got growth rate of 0.44 nm/hr per 1E7/cm3 of H2SO4. Table 2 shows ~ 0.24-0.27 nm/hr per 1E7/cm3 of H2SO4. Did I miss something here?
7. Lines 382-401. Ions have been well recognized to enhance nucleation (e.g., Yu and Turco, 2000). Based on the CLOUD chamber study (Almeida et al., 2013; Riccobono et al., 2014), ion-mediated nucleation is significant or dominant when nucleation rate is below ~ 1 cm-3 s-1 but neutral nucleation takes over when nucleation rate > ~ 1 cm-3 s-1. Since the observed nucleation rates at NM were well below 1 cm-3 s-1, I think that the possible role of ion mediated nucleation in the region (e.g., Yu and Luo, 2010) should also be discussed here.
8. Lines 430-431. This conclusion is not justified. To make such a conclusion, you need to calculate the ternary nucleation rate with reasonable values of H2SO4 and NH3 concentrations. Any information about the possible NH3 gas concentrations? Due to the cold temperature and lack of significant sources, I think that NH3 gas concentrations at NM are likely to be very low. The observed 5-9 ng/m3 of ammonium in the bulk mass is about two orders of magnitude smaller than that of MSA and nss-SO4, indicating that the particles were clearly acidic. The presence of small amount of ammonium in bulk mass doesn’t necessarily imply that NH3 was involved in the nucleation as these mass might be a result of long range transport.

References:
Almeida, J., et al., Molecular understanding of sulphuric acid–amine particle nucleation in the atmosphere, Nature, 502, 359-363, 2013.
Riccobono, F., et. Al., Oxidation products of biogenic emissions contribute to nucleation of atmospheric particles, Science, 344, 717, 2014.
Yu, F., and R. P. Turco, Ultrafine aerosol formation via ion-mediated nucleation, Geophys. Res. Lett., 27, 883-886, 2000.
Yu, F., and G. Luo, Oceanic Dimethyl Sulfide Emission and New Particle Formation around the Coast of Antarctica: A Modeling Study of Seasonal Variations and Comparison with Measurements, Atmosphere, 1(1):34-50, 2010.

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ED: Reconsider after minor revisions (Editor review) (28 Sep 2015) by Fangqun Yu

AR by Rolf Weller on behalf of the Authors (02 Oct 2015) Author's response Manuscript

ED: Reconsider after minor revisions (Editor review) (06 Oct 2015) by Fangqun Yu

AR by Rolf Weller on behalf of the Authors (06 Oct 2015) Author's response Manuscript

ED: Publish as is (06 Oct 2015) by Fangqun Yu

AR by Rolf Weller on behalf of the Authors (06 Oct 2015)

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Short summary

We measured condensation particle (CP) concentrations and particle size distributions at the coastal Antarctic station Neumayer. Several nucleation events were observed, but particles did not grow up to sizes required for acting as cloud condensation nuclei. A simple estimation indicated that apart from sulfuric acid, the derived growth rates required other low volatile precursor vapours.