Estimating cloud condensation nuclei number concentrations using aerosol optical properties: role of particle number size distribution and parameterization

Shen, Yicheng; Virkkula, Aki; Ding, Aijun; Luoma, Krista; Keskinen, Helmi; Aalto, Pasi P.; Chi, Xuguang; Qi, Ximeng; Nie, Wei; Huang, Xin; Petäjä, Tuukka; Kulmala, Markku; Kerminen, Veli-Matti

doi:https://doi.org/10.5194/acp-19-15483-2019

Articles | Volume 19, issue 24

https://doi.org/10.5194/acp-19-15483-2019

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

https://doi.org/10.5194/acp-19-15483-2019

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

Articles | Volume 19, issue 24

Research article

|

18 Dec 2019

Research article |

| 18 Dec 2019

Estimating cloud condensation nuclei number concentrations using aerosol optical properties: role of particle number size distribution and parameterization

Yicheng Shen, Aki Virkkula, Aijun Ding, Krista Luoma, Helmi Keskinen, Pasi P. Aalto, Xuguang Chi, Ximeng Qi, Wei Nie, Xin Huang, Tuukka Petäjä, Markku Kulmala, and Veli-Matti Kerminen

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

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RC1: 'Review Yicheng Shen et al. ACP', Anonymous Referee #1, 06 May 2019
- AC1: 'Replies to both reviewers', Aki Virkkula, 30 Sep 2019
RC2: 'Review Shen et al.', Anonymous Referee #2, 17 May 2019
AC2: 'Revised manuscript', Aki Virkkula, 30 Sep 2019
AC3: 'Revised supplement', Aki Virkkula, 30 Sep 2019

Peer-review completion

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

AR by Aki Virkkula on behalf of the Authors (30 Sep 2019) Author's response

ED: Referee Nomination & Report Request started (01 Oct 2019) by Manabu Shiraiwa

RR by Anonymous Referee #1 (14 Oct 2019)

Suggestions for revision or reasons for rejection

Many thanks for the responses to the reviewer comments and for the revised version of the manuscript. The manuscript improved and most of the reviewer comments are addressed. However, one major issue remains – after addressing this, the manuscript can be published in ACP.

Referee #1:
Major Comment:
1) Page 1 line 26 of the Abstract is misleading. The manuscript focusses on the rela-tionship be-tween AOD and CCN, this parametrization also depends on the supersatu-ration, however the manuscript does not show that the relationship between measured CCN number concentra-tion and the corresponding supersaturation (S) is logarithmic,there is even no figure and no discussion about the relationship between CCN and Sin the manuscript.

Author:
We don't quite understand the reviewer's comment because the derived formula
NCCN ≈ ((286 ± 46)SAE ln(SS/(0.093 ± 0.006))(BSF – BSFmin) + (5.2 ± 3.3))σsp, includes a logarithmic dependence on SS. The section where this was derived included discussion also. However, we have now included a new figure that shows this clearly. Fig. 1 of the revised paper shows the averages of the measured NCCN at the six sites at the station-specific supersaturations of the CCN counters and a logaritmic fitting to the data. Also in the figures of section where the equation is derived the logarithmic and power function fittings are presented and discussed.

Referee #1:
Many thanks for implementing the new Figure 1 - this largely helps to understand the statement on the NCCN-S relationship. However, I still don’t agree with the following statement: “The analysis first showed that the dependence of NCCN on supersaturation SS is logarithmic in the range SS < 1.1%.”. This infers that finding the ln-relationship is a major discovery. However, there have been several analytical fit functions suggested for the NCCN data over S (Khain et al., 2000; Pinsky et al., 2012; Deng et al., 2013; Pohlker et al., 2016). I wonder why the authors assume that the ln-fit provides advantages over the other functions that have been published before. Moreover, what does “… is logarithmic …” mean? Shouldn’t it be rather “… can be described by a logarithmic fit …”? I wonder if the ln-fit has any physical meaning. I suggest that these aspects are discussed in detail in the text. Moreover the aforementioned statement in the abstract probably needs some clarification.

Deng, Z. Z., Zhao, C. S., Ma, N., Ran, L., Zhou, G. Q., Lu, D. R., and Zhou, X. J.: An examination of parameterizations for the CCN number concentration based on in situ measurements of aerosol activation properties in the North China Plain, Atmospheric Chemistry and Physics, 13, 6227-6237, 10.5194/acp-13-6227-2013, 2013.

Khain, A., Ovtchinnikov, M., Pinsky, M., Pokrovsky, A., and Krugliak, H.: Notes on the state-of-the-art numerical modeling of cloud microphysics, Atmospheric Research, 55, 159-224, 10.1016/s0169-8095(00)00064-8, 2000.

Pinsky, M., Khain, A., Mazin, I., and Korolev, A.: Analytical estimation of droplet concentration at cloud base, Journal of Geophysical Research-Atmospheres, 117, 10.1029/2012jd017753, 2012.

Pohlker, M. L., Pohlker, C., Klimach, T., Hrabe de Angelis, I., Barbosa, H. M. J., Brito, J., Carbone, S., Cheng, Y., Chi, X., Ditas, F., Ditz, R., Gunthe, S. S., Kesselmeier, J., Konemann, T., Lavrič, J. V., Martin, S. T., Moran-Zuloaga, D., Rose, D., Saturno, J., Su, H., Thalman, R., Walter, D., Wang, J., Wolff, S., Artaxo, P., Andreae, M. O., and Poschl, U.: Long-term observations of cloud condensation nuclei in the Amazon rain forest – Part 1: Aerosol size distribution, hygroscopicity, and new model parameterizations for CCN prediction, Atmos. Chem. Phys., 16, 15709-15740, 10.5194/acp-2016-519, 2016.

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ED: Reconsider after major revisions (15 Oct 2019) by Manabu Shiraiwa

AR by Aki Virkkula on behalf of the Authors (24 Oct 2019) Author's response Manuscript

ED: Publish as is (25 Oct 2019) by Manabu Shiraiwa

AR by Aki Virkkula on behalf of the Authors (03 Nov 2019) Manuscript

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Short summary

Long-term cloud condensation nuclei (CCN) number concentration (NCCN) data are scarce; there are a lot more data on aerosol optical properties (AOPs). It is therefore valuable to derive parameterizations for estimating NCCN from AOP measurements. With the new parameterization NCCN can be estimated from backscatter fraction, scattering Ångström exponent, and total light-scattering coefficient. The NCCN–AOP relationships depend on the geometric mean diameter and the width of the size distribution.