Evidence for the predictability of changes in the stratospheric aerosol size following volcanic eruptions of diverse magnitudes using space-based instruments

Thomason, Larry W.; Kovilakam, Mahesh; Schmidt, Anja; von Savigny, Christian; Knepp, Travis; Rieger, Landon

doi:https://doi.org/10.5194/acp-21-1143-2021

Articles | Volume 21, issue 2

https://doi.org/10.5194/acp-21-1143-2021

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

https://doi.org/10.5194/acp-21-1143-2021

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

Articles | Volume 21, issue 2

Research article

|

27 Jan 2021

Research article |

| 27 Jan 2021

Evidence for the predictability of changes in the stratospheric aerosol size following volcanic eruptions of diverse magnitudes using space-based instruments

Larry W. Thomason, Mahesh Kovilakam, Anja Schmidt, Christian von Savigny, Travis Knepp, and Landon Rieger

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Final revised paper (published on 27 Jan 2021)
Preprint (discussion started on 18 Jun 2020)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Review of the manuscript Thomason et al.', Pasquale Sellitto, 03 Jul 2020
- AC1: 'Response to Reviewer 1', Larry Thomason, 15 Oct 2020
RC2: 'Referee Report on “Evidence for the predictability of changes in the stratospheric aerosol size following volcanic eruptions of diverse magnitudes using space-based instruments”, by Thomason et al.', Anonymous Referee #2, 08 Jul 2020
- AC2: 'Response to Reviewer 2', Larry Thomason, 15 Oct 2020
RC3: 'Referee Report', Anonymous Referee #3, 20 Jul 2020
- AC3: 'Response to Reviewer 3', Larry Thomason, 15 Oct 2020

Peer-review completion

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

AR by Larry Thomason on behalf of the Authors (15 Oct 2020) Author's response

ED: Referee Nomination & Report Request started (20 Oct 2020) by Farahnaz Khosrawi

RR by Anonymous Referee #3 (13 Nov 2020)

RR by Pasquale Sellitto (16 Nov 2020)

Suggestions for revision or reasons for rejection

Dear Editor, dear Authors,

I have now reviewed the revised version of the manuscript "Evidence for the predictability of changes in the stratospheric aerosol size following volcanic eruptions of diverse magnitudes using space-based instruments". This is an interesting and useful paper. The Authors successfully tackled most of my comments and all of the major issues I have identified. Though I would have probably structured the manuscript in a slightly different way, and though I still found the paper a bit hard to follow at times, I think that it is now acceptable for publication, once my further following minor comments are tackled.

Thank you for this great paper.

My best regards,
Pasquale Sellitto

Minor Comments:

1) All new text (underlined) should be re-read because I have found many typos. Please find some in the following but the list is not exhaustive
2) Abstract, L1-5: please break up this very long sentence into two shorter sentences.
3) Abstract: "They may also represent be a distinct avenue...", there is a "be" to be suppressed?
4) Introduction, Page1: "mall-to-moderate" -->"small-to-moderate"
5) "OSIRIS, 2002- present)" --> "OSIRIS (2002- present)
6) Introduction, Page 2: "... and apparent aerosol particle size...", please define "apparent" (e.g.: "using the spectral variability of the aerosol extinction as a proxy" or similar)
7) Results, Page 4: "The spread early in extinction coefficient and in extinction coefficient ratio is primarily due to inhomogeneity in the volcanic aerosol within the analysis area.", it has been recently shown how spatial dispersion and temporal evolution (i.e. the action of in-plume physico-chemical processes) "smooth" volcanic plumes (https://www.nature.com/articles/s41598-020-71635-1). That's a well-known behaviour for volcanologists but not as well clear in atmospheric science works, so I suggest to mention this using the above reference.
8) Page 5: "In any case, these points are rare and only occur in the first month following the eruption.", why not mentioning that this can be due to removal of larger particles from the plume (sedimentation)?
9) "...a4-km..." --> "a 4-km"
10) "...(solid) and extinction coefficient ratio (dash) are well...", I would not mention line style in the text (this is something that is more for the figure caption)
11) "We will discuss some of these events in more detail below.", It is said here that individual events are discussed in the following. Nevertheless, before the specific discussions of the events, there still is a full paragraph of general discussions. I'd suppress this sentence here and add something like "We now discuss individual some events" when you start this part (i.e. for Ambae)
12) Equation at the end of Page 5: why this and the following equations are not numbered? Also, "k(max)", is this what has been called "after" (and not "max") above in the text? Please be consistent.
13) Page 6: ""eventsin" --> "events in"
14) Equation for "ratio": I would use a more specific name for this parameter, to avoid confusion between the ratio of the perturbations and the ratio of the extinctions themselves (also called ER)
15) Page 7: "For instance, for Raikoke, we cannot exclude the possibility of the presence of small amounts of ash embedded in the main aerosol layer with the sulfuric acid aerosol influencing the extinction coefficient and ratio. The presence of ash following the Raikoke eruption has been inferred above 15 km and perhaps as high as 20 km ...", this preprint (ACPD) on Raikoke eruption observed with SAGE (among other data) is now available: https://acp.copernicus.org/preprints/acp-2020-701/ . This work also suggests possible presence of ash, and more absorbing material, in the Raikoke plume, that can be used to confirm your hypothesis
16) Page 8: "However, as they coagulate into steadily larger particles (possibly also consuming small-sized aerosol present in the pre-existing aerosol layer)...", I would not be so categorical here on the fact that the microphysical processes that modify these size distributions are just coagulation; I'd mention also condensation processes here.
17) Figure 7: "Which is the starting date for each abscissa? Please double check the position of the red dashed lines: e.g. for Pinatubo, the AE perturbation seems to anticipate the eruption."

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ED: Publish subject to minor revisions (review by editor) (17 Nov 2020) by Farahnaz Khosrawi

AR by Larry Thomason on behalf of the Authors (23 Nov 2020) Author's response Manuscript

ED: Publish subject to technical corrections (25 Nov 2020) by Farahnaz Khosrawi

AR by Larry Thomason on behalf of the Authors (30 Nov 2020) Author's response Manuscript

Short summary

Measurements of the impact of volcanic eruptions on stratospheric aerosol loading by space-based instruments show show a fairly well-behaved relationship between the magnitude and the apparent changes to aerosol size over several orders of magnitude. This directly measured relationship provides a unique opportunity to verify the performance of interactive aerosol models used in climate models.