Articles | Volume 22, issue 5
https://doi.org/10.5194/cp-22-1057-2026
© Author(s) 2026. This work is distributed under the Creative Commons Attribution 4.0 License.
Cryptotephra in the East Antarctic Mount Brown South ice core
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- Final revised paper (published on 29 May 2026)
- Supplement to the final revised paper
- Preprint (discussion started on 24 Oct 2024)
- Supplement to the preprint
Interactive discussion
Status: closed
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
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RC1: 'Comment on cp-2024-64', Anonymous Referee #1, 25 Nov 2024
- AC1: 'Reply on RC1', Margaret Harlan, 04 Feb 2025
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RC2: 'Comment on cp-2024-64', Anonymous Referee #2, 07 Dec 2024
- AC2: 'Reply on RC2', Margaret Harlan, 04 Feb 2025
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RC3: 'Comment on cp-2024-64', Anonymous Referee #3, 14 Dec 2024
- AC3: 'Reply on RC3', Margaret Harlan, 04 Feb 2025
Peer review completion
AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload
ED: Reconsider after major revisions (19 Feb 2025) by Alberto Reyes
AR by Margaret Harlan on behalf of the Authors (17 Jun 2025)
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EF by Daria Karpachova (17 Jun 2025)
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ED: Referee Nomination & Report Request started (13 Nov 2025) by Denis-Didier Rousseau
RR by Anonymous Referee #1 (10 Dec 2025)
RR by Anonymous Referee #2 (22 Jan 2026)
ED: Reconsider after major revisions (26 Jan 2026) by Denis-Didier Rousseau
AR by Margaret Harlan on behalf of the Authors (16 Feb 2026)
Author's response
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ED: Referee Nomination & Report Request started (19 Feb 2026) by Denis-Didier Rousseau
RR by Anonymous Referee #1 (25 Feb 2026)
RR by Anonymous Referee #2 (13 Mar 2026)
ED: Publish subject to minor revisions (review by editor) (13 Mar 2026) by Denis-Didier Rousseau
AR by Margaret Harlan on behalf of the Authors (02 Apr 2026)
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EF by Mario Ebel (02 Apr 2026)
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ED: Publish as is (08 Apr 2026) by Denis-Didier Rousseau
AR by Margaret Harlan on behalf of the Authors (14 Apr 2026)
Manuscript
This manuscript presents new tephra measurements in the upper ~20 m of two Mount Brown South ice cores from coastal East Antarctica spanning the recent ~40 years. The authors first conduct a broad, lower resolution investigation of tephra particles in the main MBS ice core before doing more high-resolution geochemical analysis on samples on an adjacent firn core to fingerprint specific eruption sources.
Overall, I think the methods and results are described well, and the geochemical data, and therefore ties to known volcanoes, are robust. While the authors identified a wide range of sparse tephras in their samples, the interpretation is focused (in my view, rightfully so) on the two clusters of tephra identified in the two samples with the largest number of shards. For these two events, the authors identify appropriate candidate eruptions and then logically rule out unlikely eruptions to conclude that Cerro Hudson and Erebus as the sources for the tephra layers they identify in 1991 and 1985, respectively. One aspect that could be better presented is the analytical uncertainty of the geochemical measurements- often these are included as crosses on the major element diagrams (bottom 9 panels of Figs. 7 and 9, for example). I’d suggest adding these uncertainties if possible, though the analytical error is in a supplementary data table.
While the tephra data and attribution are robust, I did not find the modeling component or some aspects of the discussion to be as convincing and have the following questions/suggestions for those aspects of the manuscript:
First, the HYSPLIT modeling is used to develop air mass back trajectories for the two eruptions to show they are within the probable source region for the MBS site. Given that long-range transport is implicit to most aerosol records in Antarctica, I do not think that using such back trajectories to show that these volcanoes are within the source region is particularly useful since it seems plausible that nearly all volcanoes in the high latitude Southern Hemisphere could result in tephra deposition in Antarctica. To me, it seems the power of concretely attributing tephra to a specific volcanic source is the possibility for modeling emissions scenarios specific to that volcano. Since these eruptions are relatively well documented down to the specific eruption dates, I think running HYSPLIT in forwards mode with ash emissions for each eruption would be very useful to understand if modeled ash dispersion is consistent with the tephra identified at MBS. It may be worth mentioning that HYSPLIT back trajectories are air mass trajectories and therefore do not specifically consider aerosol transport/scavenging (which would impact tephra), but the forwards dispersion model can be specifically run for volcanic ash, though I am not sure how sophisticated the transport scheme is.
Second, I did not find that most of the discussion was justified given the limited findings of the manuscript specific to these two modern eruptions. The ice core dating section (5.1) focuses on detailing the uncertainties about ice core sulfate records and presents tephra as a more reliable means of developing tie points. I strongly disagree with this. Volcanic synchronization of ice cores using sulfate has led to the development of extremely accurate ice core chronologies (the volcanic chronologies in Sigl et al., 2014 and 2015 being some of the best recent examples) despite some of the complications associated with these records. While tephra can certainly be a powerful tool to identify specific eruptions in certain ice core records, because it is an insoluble particle it will always be much more heterogeneously distributed in the atmosphere than sulfate and therefore have much more limited utility for synchronizing geographically widespread ice core records. Furthermore, low tephra counts, reworked sparse tephras, and large sample volume required for analysis can hinder cryptotephra work. Maybe this section would be more meaningful if the authors identified these specific tephras in all four cores at MBS as well as in other regions of Antarctica to show a viable widespread signal, but identifying these shards in a single shallow core does not justify this broader discussion of ice core dating. Lastly, sections 5.2 and 5.3 seemed almost too hypothetical to be meaningful. Both sections describe how a longer MBS cryptotephra could be insightful and potentially linked to large-scale climate and teleconnections, which doesn’t particularly relate to the findings of this study. Additionally, the authors do not even show that the tephra record from the main MBS record is valid given the limited amount of available sample. All tephra results in this manuscript are from the shallow core where they were able to obtain larger sample volumes, so the sampling approach presented in this study is not applicable to the main MBS core. Overall, I suggest the authors reframe the discussion to be more pertinent and specific to their results presented in the manuscript.
Minor notes
Page 2 line 53: Very nitpicky, but I’d say a 295 m ice core is intermediate, not deep.
Page 3 line 64-65: I don’t think you justify why MBS would be more advantageous than other Antarctic sites for tephra studies. It seems like a coastal site could be even more complicated than interior sites as it would be more influenced by marine biogenic sulfur complicating the link to sulfur peaks and a coastal site presumably would be closer to exposed land and therefore sources of reworked tephra?
Page 4 line 75: Define IE (I don’t think I saw ice equivalent anywhere else before this).
Page 5 lines 87-89: what do you mean by this? Weren’t all depths sampled in the MBS main core and used to guide more detailed analysis on the shallow core? How does that link to moisture sources?
Page 6 section 2.3- this seems like a very long-winded way to say that approximate timing of eruptions was guided by linear interpolation between austral summer peaks in sulfate/Cl and austral winter peaks in Na.
Page 7 line 163- any particular reason that backtrajectories initiated at 1500 m AGL?
Page 16 Fig 7- Why is the polygon/region on the TAS diagram for Cerro Hudson a different shape on this plot than on Fig 6?
Page 17 line 306- how would sulfur isotopes allow for disentangling two coincident eruptions that appear as a single mixed sulfate peak in the ice core record? I’m not sure that is possible. I’d just remove the mention of sulfur isotopes or explain it.
Page 18 Fig 8- I’m not sure the AVHRR data appeared as intended. It seems extremely blurry.
Page 21 Fig 10- Why the switch to trajectory frequencies instead of backtrajectories? I actually find this approach more useful than individual backtrajectories so I wonder how this would look on Fig 8.
Page 25 line 481- be consistent with the number of shards. These are different than Table 1 and those stated on lines 417-418.