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Abstract Basal melting of ice shelves is a major source of mass loss from the Antarctic Ice Sheet. In situ measurements of ice shelf basal melt rates are sparse, while the more extensive estimates from satellite altimetry require precise information about firn density and characteristics of near‐surface layers. We describe a novel method for estimating multidecadal basal melt rates using airborne ice penetrating radar data acquired during a 3‐year survey of the Ross Ice Shelf. These data revealed an ice column with distinct upper and lower units whose thicknesses change as ice flows from the grounding line toward the ice front. We interpret the lower unit as continental meteoric ice that has flowed across the grounding line and the upper unit as ice formed from snowfall onto the relatively flat ice shelf. We used the ice thickness difference and strain‐induced thickness change of the lower unit between the survey lines, combined with ice velocities, to derive basal melt rates averaged over one to six decades. Our results are similar to satellite laser altimetry estimates for the period 2003–2009, suggesting that the Ross Ice Shelf melt rates have been fairly stable for several decades. We identify five sites of elevated basal melt rates, in the range 0.5–2 m a−1, near the ice shelf front. These hot spots indicate pathways into the sub‐ice‐shelf ocean cavity for warm seawater, likely a combination of summer‐warmed Antarctic Surface Water and modified Circumpolar Deep Water, and are potential areas of ice shelf weakening if the ocean warms.
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Basal Ice Unit Thickness Mapped by the NSF COLDEX MARFA Ice Penetrating Radar
This dataset contains the basal ice unit thickness as measured by the NSF COLDEX MARFA ice-penetrating radar survey, which mainly focuses on the southern flank of Dome A. The "basal ice unit" is hereby defined as the bottom portion of the ice sheet where no clear and traceable englacial reflection is detected by the radar sounder. Raw radar data can be found at: https://doi.org/10.15784/601768. The basal ice unit is mapped using the DecisionSpace Geosciences 10ep software package. This dataset provides three data products: • Thickness of the basal ice unit • Thickness of the stratigraphic ice unit above the basal ice unit • The shape of the basal ice unit boundary, where rapid basal ice unit thinning is observed in the middle of the South Pole Basin.
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- Award ID(s):
- 2019719
- PAR ID:
- 10608376
- Publisher / Repository:
- U.S. Antarctic Program (USAP) Data Center
- Date Published:
- Subject(s) / Keyword(s):
- Radar Echo Sounder Glaciology Cryosphere Coldex
- Format(s):
- Medium: X
- Location:
- Antarctica; East Antarctica; East Antarctic Plateau; (East Bound Longitude:100; North Bound Latitude:-84; South Bound Latitude:-90; West Bound Longitude:50)
- Right(s):
- Creative Commons Attribution 4.0 International
- Sponsoring Org:
- National Science Foundation
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{"Abstract":["This classified_bed data product represents the radar bed classification shown in <a href="https://doi.org/10.1098/rsta.2014.0297">Young et al., 2016</a>. Values of 0 represent specularity content below 20%; values of 3.3 represent specularity content above 20% and energy 1 microsecond below the bed 15 dB lower than the bed echo, and values of 6.7 represent specularity content above 20% and energy 1 microsecond below the bed 15 dB within than the bed echo. Grids for specularity content and post bed echo are also available. Data is available as COARDS-compliant netCDF-4/HDF5 grids (.grd) and GeoTiffs (.tiff), both in EPSG 3031 (Antarctic Polar Stereographic) projection.\n<p>\n<p>\nData were gridded using <a href="https://docs.generic-mapping-tools.org/6.1/gmt.html"> GMT6.1</a> and the <a href="https://github.com/sakov/nn-c">nnbathy</a> natural neighbor interpolator. Cell size was 1 km, gaussian filter distance was 5 km, and mask radius was 2 km.\n<p>\nBrowse images, with Bedmap3 (Pritchard et al., 2025) surface elevation contours and MEASURES phase derived surface velocities (Mouginot et al. 2019) are available for each dataset.\n\n<p>\n<p>\nAn interpretation of the values in the classified_bed product is that low values are rough bed, intermediate values are isotropic wet bed, and high values are anisotropic wet bed.\n\nVersion 1 includes data from the 2016 paper, including AGASEA over Thwaites Glacier (Holt et al., 2006), ATRS over West Antarctica (Peters et al., 2005), GIMBLE over Marie Byrd Land (Young et al, 2013) and parts of ICECAP over Wilkes Subglacial Basin, Dome C, Highland B and Totten Glacier. (Young et al, 2011, Young et al., 2016). We expect updates to the coverage as part of work funded by the Arête Glaciers Initiative.\n\n<p>\n<b>References</b>\n<br>\nHolt, J. W., Blankenship, D. D., Morse, D. L., Young, D. A., Peters, M. E., Kempf, S. D., Richter, T. G., Vaughan, D. G., and Corr, H., New boundary conditions for the West Antarctic ice sheet: subglacial topography of the Thwaites and Smith Glacier catchments, 2006, Geophysical Research Letters, 33 (L09502), pp., https://doi.org/10.1029/2005GL025561\n<br>\nMouginot, J., Rignot, E., and Scheuchl, B., Continent-wide, interferometric SAR phase, mapping of Antarctic ice velocity, 2019, Geophysical Research Letters, 46(16), pp.9710-9718, https://doi.org/10.1029/2019GL083826\n<br>\nPeters, M. E., Blankenship, D. D., and Morse, D. L., Analysis techniques for coherent airborne radar sounding: Application to West Antarctic ice streams, 2005 ,Journal of Geophysical Research, 110(B06303), pp.,https://doi.org/10.1029/2004JB003222\n<br>\nPritchard, H. D., and others.,Bedmap3 updated ice bed, surface and thickness gridded datasets for Antarctica,2025,Scientific Data,12(1), pp.414,https://doi.org/10.1038/s41597-025-04672-y\n<br>\nYoung, D. A., D. D. Blankenship, J. S. Greenbaum, E. Quartini, G. L. Muldoon, F. Habbal, L. E. Lindzey, C. A. Greene, E. M. Powell, G. C. Ng, T. G. Richter, G. Echeverry, and S. Kempf, 2024, Geophysical Investigations of Marie Byrd Land Lithospheric Evolution (GIMBLE) Airborne VHF Radar Transects: 2012/2013 and 2014/2015, https://doi.org/10.18738/T8/BMXUHX, Texas Data Repository\n<br>\nYoung, D. A., Wright, A. P., Roberts, J. L., Warner, R. C., Young, N. W., Greenbaum, J. S., Schroeder, D. M., Holt, J. W., Sugden, D. E., Blankenship, D. D., van Ommen, T. D., and Siegert, M. J.,A dynamic early East Antarctic Ice Sheet suggested by ice covered fjord landscapes, 2011, Nature, 474, pp.72-75, https://doi.org/10.1038/nature10114\n<br>\nYoung, D. A., Schroeder, D. M., Blankenship, D. D., Kempf, S. D., and Quartini, E.,The distribution of basal water between Antarctic subglacial lakes from radar sounding,2016,Philosophical Transactions of the Royal Society A, 374 (20140297), pp.1-21, https://doi.org/10.1098/rsta.2014.0297\n\n<p>\n<b>Change Log</b>\n<br>\nChanges from V1: changes to gridding parameters to more closely match the figures from Young 2016; updated metadata gridding description"]}more » « less
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