Preprints
https://doi.org/10.5194/egusphere-2023-1838
https://doi.org/10.5194/egusphere-2023-1838
17 Aug 2023
 | 17 Aug 2023

Evolution of layered density and microstructure in near‐surface firn around Dome Fuji, Antarctica

Ryo Inoue, Shuji Fujita, Kenji Kawamura, Ikumi Oyabu, Fumio Nakazawa, and Hideaki Motoyama

Abstract. To better understand the near‐surface evolution of polar firn in low accumulation areas (<30 mm w.e. yr−1), we investigated the physical properties: density, microstructural anisotropy of ice matrix and pore space, and specific surface area (SSA), of six firn cores collected within 60 km around Dome Fuji, East Antarctica. The physical properties were measured at the intervals of ≤0.02 m over the top 10 m of the cores. The main findings are: (i) lack of significant density increase in the top ~4 m, (ii) lower density near the dome summit (~330 kg m−3) than the surrounding slope area (~355 kg m−3), (iii) developments of vertically elongated microstructure and its contrast between layers within the top ~3 m, (iv) more pronounced vertical elongation at sites and periods with lower accumulation rates than those with higher accumulation rates, (v) rapid decrease in SSA in the top ~3 m, and (vi) lower SSA at lower accumulation sites, but this trend is less pronounced than that of microstructural anisotropy. These observations can be explained by the combination of the initial physical properties on the surface set by wind conditions and the metamorphism driven by water vapor transport through the firn column under a strong vertical temperature gradient (temperature gradient metamorphism, TGM). The magnitude of TGM depends on the duration of firn layers under temperature gradient, determined by accumulation rate; longer exposure causes a more vertically elongated microstructure and lower SSA. Overall, we highlight the significant spatial variability in the near-surface physical properties over the scale of ~100 km around Dome Fuji. These findings will help better understand the densification over the whole firn column and the gas trapping process in deep firn, and possible difference in them between existing deep ice cores and the upcoming “Oldest-Ice” cores collected tens of kilometers apart.

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Journal article(s) based on this preprint

30 Jan 2024
Spatial distribution of vertical density and microstructure profiles in near-surface firn around Dome Fuji, Antarctica
Ryo Inoue, Shuji Fujita, Kenji Kawamura, Ikumi Oyabu, Fumio Nakazawa, Hideaki Motoyama, and Teruo Aoki
The Cryosphere, 18, 425–449, https://doi.org/10.5194/tc-18-425-2024,https://doi.org/10.5194/tc-18-425-2024, 2024
Short summary
Ryo Inoue, Shuji Fujita, Kenji Kawamura, Ikumi Oyabu, Fumio Nakazawa, and Hideaki Motoyama

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1838', Ghislain Picard, 10 Oct 2023
    • AC2: 'Reply on RC1', Ryo Inoue, 30 Nov 2023
  • RC2: 'Comment on egusphere-2023-1838', Z.R. Courville, 29 Oct 2023
    • AC1: 'Reply on RC2', Ryo Inoue, 30 Nov 2023

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-1838', Ghislain Picard, 10 Oct 2023
    • AC2: 'Reply on RC1', Ryo Inoue, 30 Nov 2023
  • RC2: 'Comment on egusphere-2023-1838', Z.R. Courville, 29 Oct 2023
    • AC1: 'Reply on RC2', Ryo Inoue, 30 Nov 2023

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
ED: Publish subject to minor revisions (review by editor) (06 Dec 2023) by Tas van Ommen
AR by Ryo Inoue on behalf of the Authors (08 Dec 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (17 Dec 2023) by Tas van Ommen
AR by Ryo Inoue on behalf of the Authors (18 Dec 2023)  Manuscript 

Journal article(s) based on this preprint

30 Jan 2024
Spatial distribution of vertical density and microstructure profiles in near-surface firn around Dome Fuji, Antarctica
Ryo Inoue, Shuji Fujita, Kenji Kawamura, Ikumi Oyabu, Fumio Nakazawa, Hideaki Motoyama, and Teruo Aoki
The Cryosphere, 18, 425–449, https://doi.org/10.5194/tc-18-425-2024,https://doi.org/10.5194/tc-18-425-2024, 2024
Short summary
Ryo Inoue, Shuji Fujita, Kenji Kawamura, Ikumi Oyabu, Fumio Nakazawa, and Hideaki Motoyama
Ryo Inoue, Shuji Fujita, Kenji Kawamura, Ikumi Oyabu, Fumio Nakazawa, and Hideaki Motoyama

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Short summary
We measured the density, microstructural anisotropy, and specific surface area (SSA) of six firn cores collected within 60 km around Dome Fuji, Antarctica. We found a lack of significant density increase, development of vertically elongated microstructure, and rapid decrease in SSA in the top few meters due to the metamorphism driven by water vapor transport under a temperature gradient. We highlight the significant spatial variability in the properties, which depends on accumulation rate.