Preprints
https://doi.org/10.5194/egusphere-2023-157
https://doi.org/10.5194/egusphere-2023-157
23 Feb 2023
 | 23 Feb 2023

Stagnant ice and age modelling in the Dome C region, Antarctica

Ailsa Chung, Frédéric Parrenin, Daniel Steinhage, Robert Mulvaney, Carlos Martín, Marie G. P. Cavitte, David A. Lilien, Veit Helm, Drew Taylor, Prasad Gogineni, Catherine Ritz, Massimo Frezzotti, Charles O'Neill, Heinrich Miller, Dorthe Dahl-Jensen, and Olaf Eisen

Abstract. We present a 1D numerical model which calculates the age of ice around Dome C. It accounts either for melting or for a layer of stagnant ice above the bedrock, depending on the value of an inverted mechanical ice thickness. It is constrained by horizons picked from radar observations and dated using the EPICA Dome C (EDC) ice core age profile. We used 3 different radar datasets with the widest reaching airbourne radar system covering an area of 10,000 km2 and zooming in to 5 km transects over Little Dome C (LDC) with a ground based system. We find that stagnant ice exists in many places including above the LDC relief where the new Beyond EPICA drill site (BELDC) is located. The modelled thickness of this layer of stagnant ice roughly corresponds to the thickness of the basal unit observed in one of the radar surveys and observations made with Autonomous phase-sensitive Radio-Echo Sounder (ApRES). At BELDC, the modelled stagnant ice thickness is 182 ± 63 m and the modelled maximum age (that we define as the age at a maximum age density of 20 kyr m−1) is 1.49 ± 0.18 Ma at a depth of 2505 ± 34 m. This is very similar to all sites situated on the LDC relief such as that of the Million Year Ice Core project being conducted by the Australian Antarctic Division (AAD). The model was also applied to radar data in the area 10–20 km north of EDC (North Patch, NP), where we find either a thin layer of stagnant ice (generally < 60 m) or a very low melt rate (< 0.1 mm yr−1). The modelled maximum age at NP is over 2 Ma in most places, with ice at 1.5 Ma having a resolution of 9–12 kyr m−1 , making it an exciting prospect for a future oldest ice drill site.

Journal article(s) based on this preprint

24 Aug 2023
| Highlight paper
Stagnant ice and age modelling in the Dome C region, Antarctica
Ailsa Chung, Frédéric Parrenin, Daniel Steinhage, Robert Mulvaney, Carlos Martín, Marie G. P. Cavitte, David A. Lilien, Veit Helm, Drew Taylor, Prasad Gogineni, Catherine Ritz, Massimo Frezzotti, Charles O'Neill, Heinrich Miller, Dorthe Dahl-Jensen, and Olaf Eisen
The Cryosphere, 17, 3461–3483, https://doi.org/10.5194/tc-17-3461-2023,https://doi.org/10.5194/tc-17-3461-2023, 2023
Short summary Co-editor-in-chief

Ailsa Chung et al.

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-157', Anonymous Referee #1, 22 Mar 2023
    • AC1: 'Reply on RC1', Ailsa Chung, 09 Jun 2023
  • RC2: 'Comment on egusphere-2023-157', Johannes Sutter, 18 Apr 2023
    • AC2: 'Reply on RC2', Ailsa Chung, 09 Jun 2023

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-157', Anonymous Referee #1, 22 Mar 2023
    • AC1: 'Reply on RC1', Ailsa Chung, 09 Jun 2023
  • RC2: 'Comment on egusphere-2023-157', Johannes Sutter, 18 Apr 2023
    • AC2: 'Reply on RC2', Ailsa Chung, 09 Jun 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) (12 Jun 2023) by Joseph MacGregor
AR by Ailsa Chung on behalf of the Authors (12 Jun 2023)  Author's response   Author's tracked changes   Manuscript 
ED: Publish as is (15 Jun 2023) by Joseph MacGregor
AR by Ailsa Chung on behalf of the Authors (30 Jun 2023)  Author's response   Manuscript 

Post-review adjustments

AA: Author's adjustment | EA: Editor approval
AA by Ailsa Chung on behalf of the Authors (21 Aug 2023)   Author's adjustment   Manuscript
EA: Adjustments approved (23 Aug 2023) by Joseph MacGregor

Journal article(s) based on this preprint

24 Aug 2023
| Highlight paper
Stagnant ice and age modelling in the Dome C region, Antarctica
Ailsa Chung, Frédéric Parrenin, Daniel Steinhage, Robert Mulvaney, Carlos Martín, Marie G. P. Cavitte, David A. Lilien, Veit Helm, Drew Taylor, Prasad Gogineni, Catherine Ritz, Massimo Frezzotti, Charles O'Neill, Heinrich Miller, Dorthe Dahl-Jensen, and Olaf Eisen
The Cryosphere, 17, 3461–3483, https://doi.org/10.5194/tc-17-3461-2023,https://doi.org/10.5194/tc-17-3461-2023, 2023
Short summary Co-editor-in-chief

Ailsa Chung et al.

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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.

Oldest Ice is a large project with broad interest and appealing targets. This study shows (i) that the current Beyond EPICA and Million Year Ice Core drilling projects at Little Dome C in Antarctica are expected to extract continuous ice core of almost 1.5 million years; and (ii) estimates the spatial extent of a stagnant ice layer in the Dome C region. This layer of ice could be millions of years old and could have large scale implications for the whole Antarctic ice sheet dynamics.
Short summary
We combined a numerical model with radar measurements in order to determine the age of ice in the Dome C region of Antarctica. Our results show that at the current ice core drilling site on Little Dome C, the maximum age of the ice is around 1.5 Ma. We also highlight a new potential drill site called North Patch with ice up to 2 Ma. Finally, we explore the nature of a stagnant ice layer at the base of the ice sheet which has been independently observed and modelled but is not well understood.