the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 22 Sep 2025
Basal Unit Radar Characteristics at the Southern Flank of Dome A, East Antarctica
Abstract. The basal unit near the base of the Antarctic Ice Sheet (AIS) plays a critical role in AIS dynamics and the preservation of old ice, yet its structure and origin remain poorly understood. Using a new airborne ice-penetrating radar dataset collected by the NSF Center for Oldest Ice Exploration (NSF COLDEX), we investigate the radar characteristics of the basal unit at the southern flank of Dome A, East Antarctica. We combine manual mapping with Delay-Doppler analysis to characterize the spatial distribution of incoherent scattering and to distinguish between two types of radar-apparent basal unit top boundaries: a sharp transition from specular to scattering reflections (type I) and a gradual disappearance of specular reflections due to radar signal attenuation (type II). We find that incoherent scattering is widespread upstream and decreases downstream, correlating with both subglacial topographic roughness and a shift from type I to type II boundaries. These patterns are interpreted as resulting from spatial variability in englacial temperature, with warmer ice downstream enhancing signal attenuation and obscuring radar features. Although incoherent scattering is not visible in the downstream region, its absence may reflect radar detection limits rather than true absence of scattering reflectors in the basal unit. Moreover, the observed correlation between scattering and subglacial roughness suggests deeper geological controls in which subglacial lithology influences both basal temperature and subglacial geomorphology.
Competing interests: At least one of the (co-)authors is a member of the editorial board of The Cryosphere. The peer-review process was guided by an independent editor, and the authors also have no other competing interests to declare.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.-
Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
(10498 KB)
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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.
- Preprint
(10498 KB) - Metadata XML
- BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2025-3944', Steven Franke, 28 Sep 2025
- AC1: 'Reply on RC1', Shuai Yan, 06 Dec 2025
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RC2: 'Comment on egusphere-2025-3944', Alvaro Arenas Pingarron, 20 Oct 2025
Review of https://doi.org/10.5194/egusphere-2025-3944: ‘Basal Unit Radar Characteristics at the Southern Flank of Dome A, East Antarctica’, by Yan et al.
Dear authors,
Your article describes the englacial basal units classified from the analysis of scattering in radar images. You discuss two types of units, depending on how sharp or gradual is the scattering variation, and relate the transition spatial transition between units to changes in englacial temperature and bed geomorphology. From my point of view, the main contributions of the article are the methods for limiting the upper layer of the basal unit, and for classifying the basal content with the two discussed types.
The structure of the paper facilitates the reading. In particular, the introduction nicely explains what the reader will find in the article. The images are very well chosen and meaningful, with scientific colour maps for universal interpretation. The references I checked support the article. The data are in public repositories and are open, except one data set, maybe currently under embargo.
In the attached pdf, I include my comments and suggested additions and minor corrections. My main comments are related to how reflections are classified between specular or scattering, to the interpretation of the two discussed types of basal unit types, and to the presence of sidelobes in the SAR images.
Regards,
Álvaro Arenas-Pingarrón
- AC2: 'Reply on RC2', Shuai Yan, 06 Dec 2025
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2025-3944', Steven Franke, 28 Sep 2025
- AC1: 'Reply on RC1', Shuai Yan, 06 Dec 2025
-
RC2: 'Comment on egusphere-2025-3944', Alvaro Arenas Pingarron, 20 Oct 2025
Review of https://doi.org/10.5194/egusphere-2025-3944: ‘Basal Unit Radar Characteristics at the Southern Flank of Dome A, East Antarctica’, by Yan et al.
Dear authors,
Your article describes the englacial basal units classified from the analysis of scattering in radar images. You discuss two types of units, depending on how sharp or gradual is the scattering variation, and relate the transition spatial transition between units to changes in englacial temperature and bed geomorphology. From my point of view, the main contributions of the article are the methods for limiting the upper layer of the basal unit, and for classifying the basal content with the two discussed types.
The structure of the paper facilitates the reading. In particular, the introduction nicely explains what the reader will find in the article. The images are very well chosen and meaningful, with scientific colour maps for universal interpretation. The references I checked support the article. The data are in public repositories and are open, except one data set, maybe currently under embargo.
In the attached pdf, I include my comments and suggested additions and minor corrections. My main comments are related to how reflections are classified between specular or scattering, to the interpretation of the two discussed types of basal unit types, and to the presence of sidelobes in the SAR images.
Regards,
Álvaro Arenas-Pingarrón
- AC2: 'Reply on RC2', Shuai Yan, 06 Dec 2025
Peer review completion
Journal article(s) based on this preprint
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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.
- Preprint
(10498 KB) - Metadata XML
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