Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Spatial complexity of ice flow across the Antarctic Ice Sheet

Abstract

Fast-flowing ice streams carry ice from the interior of the Antarctic Ice Sheet towards the coast. Understanding how ice-stream tributaries operate and how networks of them evolve is essential for developing reliable models of the ice sheet’s response to climate change1,2,3,4,5,6. A particular challenge is to unravel the spatial complexity of flow within and across tributary networks. Here I define a measure of planimetric flow convergence, which can be calculated from satellite measurements of the ice sheet’s surface velocity, to explore this complexity. The convergence map of Antarctica clarifies how tributaries draw ice from its interior. The map also reveals curvilinear zones of convergence along lateral shear margins of streaming, and abundant ripples associated with nonlinear ice rheology and changes in bed topography and friction. Convergence on ice-stream tributaries and their feeding zones is uneven and interspersed with divergence. For individual drainage basins, as well as the ice sheet as a whole, fast flow cannot converge or diverge as much as slow flow. I therefore deduce that flow in the ice-stream networks is subject to mechanical regulation that limits flow-orthonormal strain rates. These findings provide targets for ice-sheet simulations and motivate more research into the origin and dynamics of tributarization.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type

from$1.95

to$39.95

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Ice-flow convergence across Antarctica.
Figure 2: Convergence pattern in an area of Bindschadler Ice Stream overlying bumpy bed.
Figure 3: Convergence, speed, and cross-flow strain-rate distributions.

Similar content being viewed by others

References

  1. Bamber, J. L., Vaughan, D. G. & Joughin, I. Widespread complex flow in the interior of the Antarctic Ice Sheet. Science 287, 1248–1250 (2000).

    Article  Google Scholar 

  2. Alley, R. B. & Bindschadler, R. A. in The West Antarctic Ice Sheet: Behavior and Environment Vol. 77 (eds Alley, R. B. & Bindschadler, R. A.) 1–11 (Antarctic Research Series, American Geophysical Union, 2001).

    Book  Google Scholar 

  3. Bennett, M. R. Ice streams as the arteries of an ice sheet: Their mechanics, stability and significance. Earth Sci. Rev. 61, 309–339 (2003).

    Article  Google Scholar 

  4. Hulbe, C. & Fahnestock, M. Century-scale discharge stagnation and reactivation of the Ross ice streams, West Antarctica. J. Geophys. Res. 112, F03S27 (2007).

    Article  Google Scholar 

  5. Joughin, I. & Alley, R. B. Stability of the West Antarctic ice sheet in a warming world. Nature Geosci. 4, 506–513 (2011).

    Article  Google Scholar 

  6. Rignot, E., Mouginot, J. & Scheuchl, B. Ice flow of the Antarctic Ice Sheet. Science 333, 1427–1430 (2011).

    Article  Google Scholar 

  7. Glasser, N. F. & Gudmundsson, G. H. Longitudinal surface structures (flowstripes) on Antarctic glaciers. Cryosphere 6, 383–391 (2012).

    Article  Google Scholar 

  8. Stokes, C. R. & Clark, C. D. Palaeo-ice streams. Quat. Sci. Rev. 20, 1437–1457 (2001).

    Article  Google Scholar 

  9. King, E. C., Woodward, J. & Smith, A. M. Seismic and radar observations of subglacial bed forms beneath the onset zone of Rutford Ice Stream, Antarctica. J. Glaciol. 53, 665 − 672 (2007).

    Article  Google Scholar 

  10. Alley, R. B., Blankenship, D. D., Bentley, C. R. & Rooney, S. T. Deformation of till beneath Ice Stream B, West Antarctica. Nature 322, 57–59 (1986).

    Article  Google Scholar 

  11. Anandakrishnan, S., Blankenship, D. D., Alley, R. B. & Stoffa, P. L. Influence of subglacial geology on the position of a West Antarctic ice stream from seismic observations. Nature 394, 62–65 (1998).

    Article  Google Scholar 

  12. Raymond, C. F., Catania, G. A., Nereson, N. & Van der Veen, C. J. Bed radar reflectivity across the north margin of Whillans Ice Stream, West Antarctica, and implications for margin processes. J. Glaciol. 52, 3–10 (2006).

    Article  Google Scholar 

  13. Ng, F. & Conway, H. Fast-flow signature in the stagnated Kamb Ice Stream, West Antarctica. Geology 32, 481–484 (2004).

    Article  Google Scholar 

  14. Kamb, B. in The West Antarctic Ice Sheet: Behavior and Environment Vol. 77 (eds Alley, R. B. & Bindschadler, R. A.) 157–199 (Antarctic Research Series, American Geophysical Union, 2001).

    Google Scholar 

  15. Raymond, C. F. Energy balance of ice streams. J. Glaciol. 46, 665–674 (2000).

    Article  Google Scholar 

  16. Sayag, R. & Tziperman, E. Interaction and variability of ice streams under a triple-valued sliding law and non-Newtonian rheology. J. Geophys. Res. 116, F01009 (2011).

    Article  Google Scholar 

  17. Kyrke-Smith, T. M., Katz, R. F. & Fowler, A. C. Subglacial hydrology and the formation of ice streams. Proc. R. Soc. A 470, 20130494 (2013).

    Article  Google Scholar 

  18. Kleiner, T. & Humbert, A. Numerical simulations of major ice streams in western Dronning Maud Land, Antarctica, under wet and dry basal conditions. J. Glaciol. 60, 215–232 (2014).

    Article  Google Scholar 

  19. Joughin, I., Smith, B. E. & Medley, B. Marine ice sheet collapse potentially under way for the Thwaites Glacier Basin, West Antarctica. Science 344, 735–738 (2014).

    Article  Google Scholar 

  20. Robel, A. A., DeGiuli, E., Schoof, C. & Tziperman, E. Dynamics of ice stream temporal variability: Modes, scales, and hysteresis. J. Geophys. Res. 118, 925–936 (2013).

    Article  Google Scholar 

  21. Schoof, C. Thermally driven migration of ice-stream shear margins. J. Fluid Mech. 712, 552–578 (2012).

    Article  Google Scholar 

  22. Bingham, R. G. et al. Inland thinning of West Antarctic Ice Sheet steered along subglacial rifts. Nature 487, 468–471 (2012).

    Article  Google Scholar 

  23. Nye, J. F. A topological approach to the strain-rate pattern of ice sheets. J. Glaciol. 39, 10–14 (1993).

    Article  Google Scholar 

  24. Fretwell, P. et al. BEDMAP2: Improved ice bed, surface, and thickness datasets for Antarctica. Cryosphere 7, 375–393 (2013).

    Article  Google Scholar 

  25. Gudmundsson, G. H. Transmission of basal variability to a glacier surface. J. Geophys. Res. 108, 2253 (2003).

    Article  Google Scholar 

  26. Hulbe, C. L. & Whillans, I. M. Weak bands within Ice Stream B, West Antarctica. J. Glaciol. 43, 377–386 (1997).

    Article  Google Scholar 

  27. Stokes, C. R., Clark, C. D., Lian, O. B. & Tulaczyk, S. Ice stream sticky spots: A review of their identification and influence beneath contemporary and palaeo-ice streams. Earth Sci. Rev. 81, 217–249 (2007).

    Article  Google Scholar 

  28. Sergienko, O. V. & Hindmarsh, R. C. A. Regular patterns in frictional resistance of ice-stream beds seen by surface data inversion. Science 342, 1086–1089 (2013).

    Article  Google Scholar 

  29. Budd, W. F. & Warner, R. C. A computer scheme for rapid calculations of balance-flux distributions. Ann. Glaciol. 23, 21 − 27 (1996).

    Article  Google Scholar 

  30. Dodds, P. S. & Rothman, D. H. Scaling, universality and geomorphology. Annu. Rev. Earth Planet. Sci. 28, 571–610 (2000).

    Article  Google Scholar 

  31. Rignot, E., Mouginot, J. & Scheuchl, B. MEaSUREs InSAR-Based Antarctica Ice Velocity Map (NASA National Snow and Ice Data Center Distributed Active Archive Center, Boulder, Colorado, 2011); http://dx.doi.org/10.5067/MEASURES/CRYOSPHERE/nsidc-0484.001

    Google Scholar 

  32. Isaaks, E. H. & Srivastava, R. M. Applied Geostatistics (Oxford Univ. Press, 1989).

    Google Scholar 

  33. Kitanidis, P. K. Introduction to Geostatistics: Applications in Hydrogeology (Cambridge Univ. Press, 1997).

    Book  Google Scholar 

  34. Young, D. S. Random vectors and spatial analysis by geostatistics for geotechnical applications. Math. Geol. 19, 467–479 (1987).

    Article  Google Scholar 

  35. Gumiaux, C., Gapais, D. & Brun, J. P. Geostatistics applied to best-fit interpolation of orientation data. Tectonophysics 376, 241–259 (2003).

    Article  Google Scholar 

  36. Philip, R. D. & Kitanidis, P. K. Geostatistical estimation of hydraulic head gradients. Ground Water 27, 855–865 (1989).

    Article  Google Scholar 

  37. Fisher, N. I. Statistical Analysis of Circular Data (Cambridge Univ. Press, 1993).

    Book  Google Scholar 

  38. Bamber, J. L., Gomez-Dans, J. L. & Griggs, J. A. A new 1 km digital elevation model of the Antarctic derived from combined satellite radar and laser data—Part 1: Data and methods. Cryosphere 3, 101–111 (2009).

    Article  Google Scholar 

Download references

Acknowledgements

I thank H. Conway, D. R. MacAyeal and D. J. Jerolmack for their comments on the manuscript and J. L. Bamber for providing balance-velocity data.

Author information

Authors and Affiliations

Authors

Contributions

F.S.L.N. designed the study, computed and analysed the convergence map, and wrote the paper.

Corresponding author

Correspondence to Felix S. L. Ng.

Ethics declarations

Competing interests

The author declares no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 915 kb)

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Ng, F. Spatial complexity of ice flow across the Antarctic Ice Sheet. Nature Geosci 8, 847–850 (2015). https://doi.org/10.1038/ngeo2532

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/ngeo2532

This article is cited by

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing