Share This Article:

Thermal convection in ice sheets: New data, new tests

Abstract Full-Text HTML XML Download Download as PDF (Size:2533KB) PP. 409-418
DOI: 10.4236/ns.2012.47056    3,987 Downloads   6,581 Views  

ABSTRACT

Thermal convection in the Antarctic Ice Sheet was proposed in 1970. Demonstrating its existence proved to be elusive. In 2009, tributaries to ice streams were postulated as the surface expression of underlying thermal convection rolls aligned in directions of advective ice flow. Two definitive tests of this hypothesis are now possible, using highly accurate ice elevations and velocities provided by the European, Japanese, and Canadian Space Agencies that allow icestream tributaries and their velocities to be mapped. These tests are 1) measuring lowering of tributary surfaces to see if lowering is due only to advective ice thinning, or also requires lowering en masse in the broad descending part of convective flow, and 2) measuring transverse surface ice velocities to see if ice entering tributaries from the sides increases while crossing lateral shear zones, as would be required if this flow is augmented by convective flow ascending in the narrow side shear zones and diverted into tributaries by advective ice flow. If (1) and (2) are applied to tributaries converging on Byrd Glacier, the same measurements can be conducted when tributaries pack together to become “flow stripes” down Byrd Glacier and onto the Ross Ice Shelf to see if (2) is reduced when lateral advection stops. This could determine if thermal convection remains active or shuts down as ice thins. Thermal convection in the Antarctic Ice Sheet would raise three questions. Can it cause the ice sheet to self-destruct as convective flow turns on and off? Does it render invalid climate records extracted at depth from ice cores? Can the ice sheet be studied as a miniature mantle analogous in some respects to Earth’s mantle?

Conflicts of Interest

The authors declare no conflicts of interest.

Cite this paper

Hughes, T. (2012) Thermal convection in ice sheets: New data, new tests. Natural Science, 4, 409-418. doi: 10.4236/ns.2012.47056.

References

[1] Strutt, J.W. and Rayleigh III, B. (1916) On convection currents in a horizontal layer of fluid, when the higher temperature is on the underside. Philosophical Magazine (Sixth Series), 32, 529-546.
[2] Gallagher, A.P. and Mercer, A.M. (1965) On the behaviour of small distrubances in plane Couette flow with a temperatue gradient. Proceedings of the Royal Society of London, Series A, 228, 117-128. doi:10.1098/rspa.1965.0133
[3] Davies-Jones, R.P. (1971) Thermal convection in a horizontal plane Couette flow. Journal of Fluid Mechanics, 49, 193-205. doi:10.1017/S0022112071002003
[4] Weertman, J. (1967) The effect of a low viscosity layer on convection in the mantle. Geophysical Journal of the Royal Astronomical Society, 14, 353-370. doi:10.1111/j.1365-246X.1967.tb06251.x
[5] Hughes, T. (1976) The theory of thermal convection in polar ice sheets. Journal of Glaciology, 16, 41-71.
[6] Rignot, E., Mouginet, J. and Scheichl, B. (2011) NASA research yields field map of Antarctic ice flow. NASA News. www.jpl.nasa.gov/news/news.cfm?release=2011-256&cid=release
[7] Gow, A.J., Ueda, H.T. and Garfield, D.E. (1968) Antarctic ice sheets: Preliminary results of first core hole to bedrock. Science, 161, 1011-1013. doi:10.1126/science.161.3845.1011
[8] Hughes, T. (1970) Convection in the Antarctic ice sheet leading to a surge of the ice sheet and possibly to a new Ice Age. Science, 170, 630-633. doi:10.1126/science.170.3958.630
[9] Bentley, C.R. (1971) Seismic anisotrophy in the West Antarctic ice sheet. In: Crary, A.P., Ed., Antarctic Snow and Ice Studies II, Antarctic Research Series, American Geophysical Union, Washington, DC, 16, 131-177. doi:10.1029/AR016p0131
[10] Harrison, C.H. (1971) Radio-echo sounding: Focusing effects in wavy strata. Geophysical Journal of the Royal Astronomical Society, 24, 383-400. doi:10.1111/j.1365-246X.1971.tb02185.x
[11] Harrison, C.H. (1971) Radio echo records cannot be used as evidence for convection in the Antarctic ice sheet. Science, 173, 166-167. doi:10.1126/science.173.3992.166
[12] Paterson, W.S.B. (1981) The physics of glaciers. 2nd Edition, Pergamon Press, Oxford.
[13] Hughes, T. (1985) Thermal convection in ice sheets: We look but do not see. Journal of Glaciology, 31, 39-48.
[14] De Robin, G.Q. and Millar D.H.M. (1982) Flow of ice sheets in the vicinity of subglacial peaks. Annals of Glaciology, 3, 290-294.
[15] Hughes, T. (1998) Ice sheets. Oxford University Press, New York.
[16] Prasad, G. (2011) Personal communication.
[17] Hughes, T. (1972) Derivation of the critical Rayleigh Number for convection in crystalline solids. Journal of Applied Physics, 43, 2895-2896. doi:10.1063/1.1661614
[18] Hughes, T. (1972) Thermal convection in polar ice sheets related to the variousimperical flow laws of ice. Geophysical Journal of the Royal Astronomical Society, 27, 215-229. doi:10.1111/j.1365-246X.1972.tb05773.x
[19] Hughes, T.J. (1977) Do oxygen isotope data from deep coreholes reveal dike-sill thermal convection in polar ice sheets? Isotopes and Impurities in Snow and Ice, 118, 336-340.
[20] Mayewski, P.A., Meeker, L.D., Twickler, M.S., Whitlow, S., Yang, Q. and Prentice, M. (1997) Major features and forcing of high latitude Northern Hemisphere atmosphericcirculation using a 110,000 year long glaciochemical series. Journal of Geophysical Research (Special Issue-Oceans/Atmosphere), 102, 26, 345-366.
[21] Hughes, T. (2009) Thermal convection and the origin of ice streams. Journal of Glaciology, 55, 524-536. doi:10.3189/002214309788816722
[22] Sargent, A. (2009) Modeling ice streams. Ph.D. Thesis, University of Maine, Orono.
[23] Jezek, K.C. (2008) The Radarsar-1 Antarctic mapping project. Byrd Polar Research Center Report No. 22, The Ohio State University, Columbus.
[24] Kamb, B. (2001) Basal zone of the West Antarctic ice streams and its role in lubrication of their rapid motion. In: Alley, R.B. and Bindschadler, R.A., Eds., The West Antarctic Ice Sheet: Behavior and Environment, American Geophysical Union (Antarctic Research Series) Washington DC, 157-200.
[25] Harrison, W.D., Echelmeyer, K.A. and Larsen C.F. (1998) Measurement of temperature in the margin of Ice Stream B, Antarctics, implication for margin migration and lateral drag. Journal of Glaciology, 44, 615-624.
[26] Engelhardt, H. (2012) Personal communication.
[27] Knopoff, L. (1964) The convection current hypothesis. Reviews of Geophysics, 2, 89-112. doi:10.1029/RG002i001p00089
[28] Glen, J.W. (1955) The creep of polycrystalline ice. Proceedings of the Royal Society of London, Series A, 228, 519-538. doi:10.1098/rspa.1955.0066
[29] Hughes, T. (2009) Variations in ice-bed coupling beneath and beyond ice streams: The force balance. Journal of Geophysical Research, 114, Article ID B04206.
[30] Hughes, T. (2011) A simple holistic hypothesis for the self-destruction of ice sheets. Quaternary Science Reviews, 30, 1829-1845. doi:10.1016/j.quascirev.2011.04.004
[31] De Robin, G.Q. (1955) Ice movement and temperature distribution in glaciers and ice sheets. Journal of Glaciology, 2, 523-532. doi:10.3189/002214355793702028
[32] Drewry, D.J. (1983) Antarctica: Glaciological and geophysical folio. Drewry, D.J., Ed., Scott Polar Research Institute, University of Cambridge, Cambridge,
[33] Hughes, T. (1975) The West Antarcic Ice Sheet: Instability, disintegratin, and initiation of ice ages. Reviews of Geophysics and Space Physics, 13, 502-526. doi:10.1029/RG013i004p00502
[34] Smith, B.E., Fricker, H.A., Joughin, I.R. and Tulaczyk S. (2009) An inventory of active subglacial lakes in Antarctica detected by ICESat (2003-2008). Journal of Glaciology, 55, 573-595. doi:10.3189/002214309789470879
[35] Hughes, T. (1971) Convection in polar ice sheets a model for convection in the Earth’s mantle. Journal of Geophysical Research, 976, 2628-2638. doi:10.1029/JB076i011p02628
[36] Hughes, T. (1973) An unstable tetrahedral mantle-convection model, continental drift, and polar ice sheets. Tectonophysics, 17, 73-88. doi:10.1016/0040-1951(73)90066-8
[37] Hughes, T. (1973) Coriolis perturbation of mantle convection related to a two-phase convection model. Tectonophysics, 18, 215-230. doi:10.1016/0040-1951(73)90047-4

  
comments powered by Disqus

Copyright © 2019 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.