Satellites have documented trends in Antarctic sea-ice extent and its variability for decades, but estimating sea-ice thickness in the Antarctic from remote sensing data remains challenging. In situ observations needed for validation of remote sensing data and sea-ice models are limited; most have been restricted to a few point measurements on selected ice floes, or to visual shipboard estimates. Here we present three-dimensional (3D) floe-scale maps of sea-ice draft for ten floes, compiled from two springtime expeditions by an autonomous underwater vehicle to the near-coastal regions of the Weddell, Bellingshausen, and Wilkes Land sectors of Antarctica. Mean drafts range from 1.4 to 5.5 m, with maxima up to 16 m. We also find that, on average, 76% of the ice volume is deformed ice. Our surveys indicate that the floes are much thicker and more deformed than reported by most drilling and ship-based measurements of Antarctic sea ice. We suggest that thick ice in the near-coastal and interior pack may be under-represented in existing in situ assessments of Antarctic sea ice and hence, on average, Antarctic sea ice may be thicker than previously thought.
Subscribe to Journal
Get full journal access for 1 year
only $4.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Parkinson, C. L. & Cavalieri, D. J. Antarctic sea ice variability and trends, 1979–2010. The Cryosphere 6, 871–880 (2012).
Sigmond, M. & Fyfe, J. C. The Antarctic sea ice response to the ozone hole in climate models. J. Clim. 27, 1336–1342 (2014).
Bitz, C. M. & Polvani, L. M. Antarctic climate response to stratospheric ozone depletion in a fine resolution ocean climate model. Geophys. Res. Lett. 39, L20705 (2013).
Bintanja, R., van Oldenborgh, G. J., Drijfhout, S. S., Wouters, B. & Katsman, C. A. Important role for ocean warming and increased ice-shelf melt in Antarctic sea-ice expansion. Nature Geosci. 6, 376–379 (2013).
Holland, P. R. & Kwok, R. Wind-driven trends in Antarctic sea-ice drift. Nature Geosci. 5, 872–875 (2012).
Massonnet, F. et al. A model reconstruction of the Antarctic sea ice thickness and volume changes over 1980–2008 using data assimilation. Ocean Modelling 64, 67–75 (2013).
Zhang, J. Modeling the impact of wind intensification on Antarctic sea ice volume. J. Clim. 27, 202–214 (2014).
Turner, J. et al. An initial assessment of Antarctic sea ice extent in the CMIP5 models. J. Clim. 26, 1473–1484 (2013).
Comiso, J. C., Kwok, R., Martin, S. & Gordon, A. L. Variability and trends in sea ice extent and ice production in the Ross Sea. J. Geophys. Res 116, C04021 (2011).
Martinson, D. G. & Iannuzzi, R. A. in Antarctic Sea Ice: Physical Processes, Interactions and Variability (ed Jeffries, M.) 243–271 (AGU, 1998).
Kwok, R. & Rothrock, D. A. Decline in Arctic sea ice thickness from submarine and ICESat records: 1958–2008. Geophys. Res. Lett 36, L15501 (2009).
Ozsoy-Cicek, B., Ackley, S., Xie, H., Yi, D. & Zwally, J. Sea ice thickness retrieval algorithms based on in-situ surface elevation and thickness values for application to altimetry. J. Geophys. Res. 118, 3807–3822 (2013).
Harms, S., Fahrbach, E. & Strass, V. H. Sea ice transports in the Weddell Sea. J. Geophys. Res. 106, 9057–9073 (2001).
Behrendt, A., Dierking, W., Fahrbach, E. & Witte, H. Sea ice draft in the Weddell Sea, measured by upward looking sonars. Earth Syst. Sci. Data 5, 209–226 (2013).
Haas, C. Evaluation of ship-based electromagnetic-inductive thickness measurements of summer sea-ice in the Bellingshausen and Amundsen Seas, Antarctica. Cold Reg. Sci. Technol. 27, 1–16 (1998).
Weissling, B., Lewis, C. L. & Ackley, S. F. Sea ice thickness and mass at Ice Station Belgica, Bellingshausen Sea, Antarctica. Deep-Sea Res. II 58, 1112–1124 (2011).
Worby, A. P. et al. Thickness distribution of Antarctic sea ice. J. Geophys. Res. 113, C05S92 (2008).
Jeffries, M. O. et al. Crystal structure, stable isotopes (δ18O), and development of sea ice in the Ross, Amundsen, and Bellingshausen seas, Antarctica. J. Geophys. Res. 99, 985–995 (1994).
Massom, R. A. et al. Extreme anomalous atmospheric circulation in the West Antarctic Peninsula region in Austral Spring and Summer 2001/02, and its profound impact on sea ice and biota. J. Clim. 19, 3544–3571 (2006).
Adolphs, U. Ice thickness variability, isostatic balance and potential for snow ice formation on ice floes in the south polar Pacific Ocean. J. Geophys. Res. 103, 24675–24691 (1998).
Tin, T. & Jeffries, M. O. Morphology of deformed first-year sea ice features in the Southern Ocean. Cold Reg. Sci. Technol. 36, 141–163 (2003).
Timmermann, R., Worby, A., Goosse, H. & Fichefet, T. Utilizing the ASPeCt sea ice thickness data set to evaluate a global coupled sea ice-ocean model. J. Geophys. Res. 109, C07017 (2004).
Holland, P. R. et al. Modelled trends in Antarctic sea ice thickness and volume. J. Clim. 27, 3784–3801 (2014).
Jeffries, M. O. et al. in Antarctic Sea Ice: Physical Processes, Interactions and Variability (ed Jeffries, M.) 89–122 (AGU, 1998).
Yi, D., Zwally, H. J. & Robbins, J. ICESat observations of seasonal and interannual variation of sea-ice freeboard and estimated thickness in the Weddell Sea, Antarctica. Annu. Glaciol. 52, 43–51 (2011).
Worby, A. P. et al. Regional-scale sea-ice and snow thickness distributions from in situ and satellite measurements over East Antarctica during SIPEX 2007. Deep Sea Res. II 58, 1125–1136 (2011).
Xie, H. et al. Sea ice thickness estimations from ICESat Altimetry over the Bellingshausen and Amundsen Seas, 2003–2009. J. Geophys. Res. 118, 2438–2453 (2013).
Kurtz, N. T. & Markus, T. Satellite observations of Antarctic sea ice thickness and volume. J. Geophys. Res. 117, C08025 (2012).
Wadhams, P., Wilkinson, J. P. & McPhail, S. D. A new view of the underside of Arctic sea ice. Geophys. Res. Lett. 33, L04501 (2006).
Wadhams, P. & Davy, T. On the spacing and draft distributions for pressure ridge keels. J. Geophys. Res. 91, 10697–10708 (1986).
Worby, A. P. The thickness distribution of sea ice and snow cover during late winter in the Bellingshausen and Amundsen seas, Antarctica. J. Geophys. Res. 101, 28441–28455 (1996).
Weeks, W. F., Ackley, S. F. & Govoni, J. Sea ice ridging in the Ross Sea, Antarctica, as compared with sites in the Arctic. J. Geophys. Res. 94, 4984–4988 (1989).
Dierking, W. Laser profiling of the ice surface topography during the Winter Weddell Gyre Study 1992. J. Geophys. Res. 100, 4807–4820 (1995).
Kwok, R. & Maksym, T. Snow depth of the Weddell and Bellingshausen sea ice covers from IceBridge surveys in 2010 and 2011: An examination. J. Geophys. Res. 119, 4144–4167 (2014).
Lowry, R. & Wadhams, T. P. On the statistical distribution of pressure ridges in sea ice. J. Geophys. Res. 84, 2487–2494 (1979).
Wadhams, P. & Horne, T. P. An analysis of ice profiles obtained by submarine sonar in the Beaufort Sea. J. Glaciol. 25, 401–424 (1980).
We are grateful for the professionalism of the officers, crew and technical staff of the RSS J. C. Ross (IceBell) and RV Aurora Australis (SIPEX-II). J. Pietro from the Woods Hole Oceanographic Institution and R. Frost and P. Alexander from the Australian Maritime College at the University of Tasmania provided assistance in the field. K. Meiners, A. Steer, P. Heil and R. Massom (AAD), and R. Scharein (UVic) provided ice and snow properties data. C. Dietz (UTAS-CSL), A. Moy (AAD) and E. Rohling (NOC) analysed the oxygen isotope data. This work was supported by the Australian Government’s Cooperative Research Centres Programme through the Antarctic Climate and Ecosystem Cooperative Research Centre. Support for the IceBell cruise was supplied by the British Antarctic Survey and NERC grant NE/H009620/1. Support for the SIPEX-2 cruise was through the Australian Antarctic Science Grant No. 4073. T.M. was supported in part by NSF grant OPP-1142075. H.S. was supported by NSF grant ANT-1039951.
The authors declare no competing financial interests.
About this article
Cite this article
Williams, G., Maksym, T., Wilkinson, J. et al. Thick and deformed Antarctic sea ice mapped with autonomous underwater vehicles. Nature Geosci 8, 61–67 (2015). https://doi.org/10.1038/ngeo2299
Climate Models as Guidance for the Design of Observing Systems: the Case of Polar Climate and Sea Ice Prediction
Current Climate Change Reports (2019)
High-frequency and meso-scale winter sea-ice variability in the Southern Ocean in a high-resolution global ocean model
Ocean Dynamics (2018)