the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 17 Dec 2025
Climate Controls on Snowfall at Coastal West Antarctic Ice Rises - Potential Ice Core Sites
Abstract. The West Antarctic Ice Sheet (WAIS) is a dynamic system where interactions between ice, ocean, and atmosphere drive significant ice mass loss, raising concerns of irreversible retreat and sea-level rise. Long-term observational records of variability and change along the WAIS coast are largely restricted to satellite observations, but more direct observations are needed, given this region’s present and future societal impact. Coastal ice rises, grounded domes of ice embedded in or along the margins of ice shelves, preserve in their accumulated snowfall high-resolution records of past climate variability that can be recovered by ice coring. These potential ice core sites offer unique opportunities to reconstruct key drivers of regional change, including modes of atmosphere-ocean variability described by the Southern Annular Mode (SAM), the Amundsen Sea Low (ASL), and El Niño–Southern Oscillation (ENSO)—and warrant exploration via climate reanalysis to assess the relative balance of climate controls at any potential ice core site. This study uses ERA5 and MERRA-2 reanalysis to evaluate the climate controls on interannual snowfall variability at thirteen WAIS coastal ice rises over the satellite era (1979–2022). Results highlight longitudinal differences in how interannual snowfall variability at coastal ice rises is influenced by SAM, ENSO, and Bellingshausen Sea atmospheric pressure anomalies. Snow accumulation (precipitation) as resolved in atmospheric reanalysis suggests that, as potential ice core sites, Dean Island and Guest Peninsula, located in the West Sector of the WAIS coast, are strongly influenced by broad Southern Hemisphere westerly wind anomalies suppressing local precipitation, making them ideal for isolating this mode of variability in paleoclimate reconstructions. In contrast, Farwell Island in the East Sector exhibits a positive relationship between precipitation and cyclonic activity associated with Bellingshausen Sea pressure variability, making it a key site for reconstructing the influence of synoptic-scale pressure systems on coastal accumulation in this region. These findings inform future ice core studies aimed at understanding WAIS climate dynamics, with implications for projections of Antarctic stability and global sea-level rise.
- Preprint
(7061 KB) - Metadata XML
- BibTeX
- EndNote
Status: final response (author comments only)
-
RC1: 'Comment on egusphere-2025-6010', Anonymous Referee #1, 12 Jan 2026
-
AC1: 'Reply on RC1', Julia Andreasen, 30 Mar 2026
The authors thank Referee 1 for their thorough and constructive review of this manuscript. In response to their comments, we have made targeted revisions to the text, including corrections to terminology, updated and added references, and clarifications to the interpretation of wind correlations and reanalysis discrepancies. A detailed point-by-point response to each comment is provided in the attached PDF.
-
AC1: 'Reply on RC1', Julia Andreasen, 30 Mar 2026
-
RC2: 'Comment on egusphere-2025-6010', Anonymous Referee #2, 16 Feb 2026
Review of "Climate Controls on Snowfall at Coastal West Antarctic Ice Rises - Potential Ice Core Sites " by Andreasen and Neff
This article presents the relationship between precipitation at Antarctic ice rises and several key atmospheric circulation or oceanic indicators (Southern Annular Mode, Amundsen Sea Low, and El Nino-Southern Oscillation). Section 1 summarizes previous Antarctic ice core sites, and presents the potential importance of future ice core drilling at Antarctic ice rises. Section 2 examines the reanalysis data and conclude to use ERA-5 in further analysis. Section 3 is the main results of the article, presenting the correlation between precipitation at 13 potential ice core sites from WAIS and atmospheric circulation indices. The analysis led to two main conclusions for the proposed ice core sites: [1] the West Sector of the WAIS coast, where precipitation is strongly influenced by Southern Hemisphere westerly winds; and [2] the East Sector, where precipitation is strongly influenced by synoptic-scale pressure systems along the Bellingshausen Sea.
I believe the methods used have not been sufficiently considered for the research purpose of assessing future ice core sites for climate reconstruction. The most critical point is that ice cores do not necessarily record precipitation; they record surface mass balance.
Surface mass balance is determined by several processes, including precipitation, refreezing of water, surface melting, sublimation of ice, and blowing snow erosion (e.g. Equation 2 of van Dalum et al., (2025)). At high annual-mean temperatures like those in Table 1, significant melting can occur during austral summer, which makes it very hard to reconstruct past precipitation. To address this issue, a global reanalysis like ERA-5 and MERRA-2 has very limited ability to address surface mass balance. Instead, I recommend that authors analyse regional climate model simulations. Recently, several regional climate simulations have been published (van Delum et al., 2025; Agosta et al., 2019). As these regional climate models have been evaluated by number of observed surface mass balance observations, These datasets have a certain degree of credibility. In fact, the Antarctic regional climate model, RACMO, has been used to examine ice-core data (Thomas et al., 2017). As those regional climate simulations were forced by reanalysis including ERA-5, I think the analysis in the current preprint can be utilized in the same manner.
Major Comments
- Section 2 presents the correlation between ERA-5 and MERRA-2, but this analysis does not guarantee that these models have sufficient ability in simulating precipitation. I recommend using the surface mass balance from the Antarctic regional model(s), as these models have been evaluated by observations. The same applies for surface air temperature.
- Table 1: The method used to calculate climate information for each ice rise point is not explained. Is the elevation the elevation of the observed terrain, or the elevation from the ERA-5 reanalysis? Also, the temperature and precipitation should have been calculated from ERA-5, but how were they calculated? Are they calculated by bilinear interpolation based on the latitude and longitude? Also, are these annual average temperatures and precipitation values calculated at a single point in the table, or are they averaged over the ice rise? Please clarify.
Specific comments
L34: I think Barr & Lovell (2014) does not fit here because the study is Antarctic Morraines.
L111: Why were these 13 ice rises selected from 30 ice rises (L109)? Is it based on the size of the ice rises? Please clarify.
L37: what does “considerable (poorly observed)” indicate? Maybe conradicting to L36.
L150: “steig box” is not a frequently used word. Maybe changed to “S12 box” or relevant in this article. In addition, Steig et al., (2012) proposed the box as an indicator of U-wind but not analyzed V-wind, so there seems to be limited reason to analyze the V-wind and discuss its relationship with Steig et al., (2012).
Table 1: unit [degC] missing in temperature. And please clarify the unit of precipitation, [freshwater mm/a, or ice mm/a].
Figure 1 caption: [1] What does “remaining” ice core sites really means? Does it mean the site is not drilled yet? Please clarify. [2] Please clarify that red dots indicate “existing” or “previous” ice core sites (if I understand correctly).
Figure 4: sentences “To reconstruct…” are unnecessary in this figure caption.
Figures 4, 5, 7, 8: Bottom figure panel showing climate index locations can be unnecessary (figure caption is sufficient).
Figures A1-A4, I don't understand why A1-A4 are necessary in this research article, because the figures seem to present a summary of previous research. Also, the caption lacks the information of red dots.
Data availability: The data used in B1 and B2 (the SAM index and the ENSO index) can be specified.
References
van Dalum, C. T., van de Berg, W. J., van den Broeke, M. R., and van Tiggelen, M.: The surface mass balance and near-surface climate of the Antarctic ice sheet in RACMO2.4p1, The Cryosphere, 19, 4061–4090, https://doi.org/10.5194/tc-19-4061-2025, 2025.
Agosta, C., Amory, C., Kittel, C., Orsi, A., Favier, V., Gallée, H., van den Broeke, M. R., Lenaerts, J. T. M., van Wessem, J. M., van de Berg, W. J., and Fettweis, X.: Estimation of the Antarctic surface mass balance using the regional climate model MAR (1979–2015) and identification of dominant processes, The Cryosphere, 13, 281–296, https://doi.org/10.5194/tc-13-281-2019, 2019.
Thomas, E. R., van Wessem, J. M., Roberts, J., Isaksson, E., Schlosser, E., Fudge, T. J., Vallelonga, P., Medley, B., Lenaerts, J., Bertler, N., van den Broeke, M. R., Dixon, D. A., Frezzotti, M., Stenni, B., Curran, M., and Ekaykin, A. A.: Regional Antarctic snow accumulation over the past 1000 years, Clim. Past, 13, 1491–1513, https://doi.org/10.5194/cp-13-1491-2017, 2017.
Citation: https://doi.org/10.5194/egusphere-2025-6010-RC2 -
AC2: 'Reply on RC2', Julia Andreasen, 31 Mar 2026
We thank Referee 2 for their thorough and constructive review of this manuscript. In response to their comments, we have made targeted revisions to the text, including clarifying the precipitation–surface mass balance relationship at our study sites, updating and expanding the methodology descriptions in Table 1 and the site selection criteria, updating terminology throughout, and revising figures and captions. A detailed point-by-point response to each comment is provided in the attached PDF.
Viewed
| HTML | XML | Total | BibTeX | EndNote | |
|---|---|---|---|---|---|
| 227 | 159 | 38 | 424 | 42 | 32 |
- HTML: 227
- PDF: 159
- XML: 38
- Total: 424
- BibTeX: 42
- EndNote: 32
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1
Julia R. Andreasen
Peter D. Neff
Coastal ice domes in West Antarctica preserve snowfall records that reflect past climate conditions. Using weather reanalysis from 1979 to 2022, this study identifies which domes best capture different climate drivers affecting the region. Western sites respond mainly to hemisphere-wide wind shifts, while eastern sites reflect regional storm patterns. These results guide where future ice cores should be drilled to reconstruct past atmospheric and oceanic changes in this vulnerable region.
Coastal ice domes in West Antarctica preserve snowfall records that reflect past climate...
Overview Comments:
The authors use contemporary reanalyses to explore the relationship (primarily) between annual snowfall and the primary modes of variability affecting ice rise locations along with West Antarctic coast to the west of sites drilled by BAS. Ice core observations to extend the contemporary record of the “pole of variability” are really needed to provide a much longer-term perspective for this critical region for global sea level rise. The goal is to identify those sites that are more favorable to reconstructing specific modes going back decades to centuries (?) in the past. The challenges that reanalyses experience prior to 1979 (Bromwich et al. 2024) emphasize the need. The authors are suitably cautious about the fidelity of reanalyses along this coast post 1979 especially that has limited direct observations. Figure 3c verifies the need for caution, although the precipitation variations in Fig. 3d are very similar. Overall, I found this analysis interesting, significant, and well done apart from a few issues that need attention, constituting a minor-major revision.
Specific Comments: