A two-component parameterization of marine ice-nucleating particles based on seawater biology and sea spray aerosol measurements in the Mediterranean Sea

Trueblood, Jonathan V.; Nicosia, Alessia; Engel, Anja; Zäncker, Birthe; Rinaldi, Matteo; Freney, Evelyn; Thyssen, Melilotus; Obernosterer, Ingrid; Dinasquet, Julie; Belosi, Franco; Tovar-Sánchez, Antonio; Rodriguez-Romero, Araceli; Santachiara, Gianni; Guieu, Cécile; Sellegri, Karine

doi:https://doi.org/10.5194/acp-21-4659-2021

Articles | Volume 21, issue 6

https://doi.org/10.5194/acp-21-4659-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

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Atmospheric deposition in the low-nutrient-low-chlorophyll...

https://doi.org/10.5194/acp-21-4659-2021

© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 21, issue 6

Research article

|

25 Mar 2021

Research article |

| 25 Mar 2021

A two-component parameterization of marine ice-nucleating particles based on seawater biology and sea spray aerosol measurements in the Mediterranean Sea

Jonathan V. Trueblood, Alessia Nicosia, Anja Engel, Birthe Zäncker, Matteo Rinaldi, Evelyn Freney, Melilotus Thyssen, Ingrid Obernosterer, Julie Dinasquet, Franco Belosi, Antonio Tovar-Sánchez, Araceli Rodriguez-Romero, Gianni Santachiara, Cécile Guieu, and Karine Sellegri

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Final revised paper (published on 25 Mar 2021)
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Preprint (discussion started on 23 Jun 2020)
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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: 'RC - 30/07/2020 14:00', Anonymous Referee #1, 30 Jul 2020
- AC1: 'Reply to Reviewer 1', Karine Sellegri, 02 Oct 2020
RC2: 'Review of “A Two-Component Parameterization of Marine Ice Nucleating Particles Based on Seawater Biology and Sea Spray Aerosol Measurements in the Mediterranean Sea” by Trueblood et al.', Anonymous Referee #2, 18 Aug 2020
- AC2: 'Response to reviewer 2', Karine Sellegri, 02 Oct 2020

Peer-review completion

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

AR by Karine Sellegri on behalf of the Authors (18 Oct 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (10 Nov 2020) by Anne Perring

RR by Anonymous Referee #1 (30 Nov 2020)

RR by Anonymous Referee #3 (21 Dec 2020)

Suggestions for revision or reasons for rejection

The paper introduces valuable new work. Firstly, the study is based in the Mediterranean, for which there is currently no data for seawater, SML and SSA IN (as far as I’m aware). Also, as the authors point out, the sea is oligotrophic, which is another new feature introduced by the work. Also, while measures of both the seawater and SML are limited and, as shown in Fig. 5, heavily weighted by an outlier there do appear to be relationships between IN at -15 C and iron and TEP, both of which are new and novel findings. There is also a nearly significant relationship between INPs in the SML and high nucleic acid bacteria (Table 1), the latter being a new category to me, and intriguing. Further, as they write, “Our results show observed INPSML/TOCSML ratios below those expected by the model proposed by W15, indicating the TOCSML in Mediterranean waters is less IN active at these temperatures than predicted by the W15 parameterization.” This is a solid and useful finding. There is much in this work to recommend it for publication.

However, there is also one significant and central, but fixable, flaw in the work. That is, the expression of IN on a surface area basis. I don’t think you can extrapolate to the degree used here. Since almost all the surface area, probably also the IN, will be in the jet drop category, which kicks in >0.5 µm, the extrapolation shown in Fig. S4 is pushing it “a bridge too far”. The lognormal distributions also don’t look realistic from my experience. I understand the desire to estimate surface area, but in this case I think it’d be better to stick with IN/L, which is a perfectly good and informative measure. You can scale it using the <0.5 µm data to adjust for the aerosol number concentration in the sea spray generated using the plunging jet apparatus to an ambient level. With regard to the DFPC, I didn’t notice any mention of volumes processed, which given the need to limit particle loading with the DFPC, and the low concentrations of IN in seawater, is needed. Pulling back from estimating surface area will also mean that explaining the extraordinarily low levels of IN per cm^2 shown in Fig. 3 will not be required; these are strangely low, and I don’t think can be explained as being due to oligotrophic waters. For example, McCluskey et al. (2018), found comparably low levels of IN in Southern Ocean water, but much higher activity on a surface area basis. I note that Reviewer 2 commented “I am wondering about the very low concentration of INPs reported for the SSA samples in comparison to literature data. It is a true number or is it an artifact related to the used method?”.

The derivation of IN on a surface area basis is so central to the paper that my concerns about its reliability and use require this to be modified, I'm sorry, before moving forward.

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ED: Reconsider after major revisions (06 Jan 2021) by Anne Perring

AR by Svenja Lange on behalf of the Authors (22 Jan 2021) Author's response

ED: Publish as is (29 Jan 2021) by Anne Perring

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Short summary

Sea spray aerosols (SSAs) can be an important source of ice-nucleating particles (INPs) that impact cloud properties over the oceans. In the Mediterranean Sea, we found that the INPs in the seawater surface microlayer increased by an order of magnitude after a rain dust event that impacted iron and bacterial abundances. The INP properties of SSA (INP_SSA) increased after a 3 d delay. Outside this event, INPSSA could be parameterized as a function of the seawater biogeochemistry.