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Radar evidence of ponded subglacial water in Greenland

  • GORDON K. A. OSWALD (a1), SOROUSH REZVANBEHBAHANI (a2) and LEIGH A. STEARNS (a2)

Abstract

The thermal state at the bed of a large ice sheet is a critical boundary condition governing its future evolution. Radar surveys provide an opportunity for direct but remote observation of the ice-sheet bed, and therefore offer a means of constraining numerical ice-sheet models at the ice–bed interface. Here we have processed results of radar surveys of the Greenland Ice Sheet undertaken by the Program for Arctic Regional Climate Assessment (PARCA) between 1999 and 2003, to explore this opportunity. We consider the robustness of the measurements in the context of uncertain dielectric losses in the ice sheet, concluding that the observed radar signal characteristics reflect the character of the bed itself rather than that of uncertain englacial absorption. However, the identification of thaw is restricted to areas where subglacial water has sufficient depth to influence the radar reflection. We derive a map of inferred areas of subglacial thaw, and compare our results with other studies predicting regions with temperate bed. We show that in many areas the radar inferences of ponded water lie within areas predicted to be thawed by modelling and radiostratigraphy. There is clear disagreement in certain areas, suggesting the presence of high geothermal flux anomalies.

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Copyright

This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited.

Corresponding author

Correspondence: Gordon K. A. Oswald <gordon.oswald@maine.edu>

References

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Bentley, CG, Thomas, RH and Velicogna, I (2007) Ice sheets. In Global outlook for ice and snow, Division of Early Warning and Assessment, United Nations Environment Programme, pp. 100114. ISBN: 9789280727999
Budd, WF, Jacka, TH, Jenssen, D, Radok, U and Young, NW (1982) Derived physical characteristics of the Greenland ice sheet, Pub. 23, Meteorology Department, University of Melbourne, Melbourne, AUS
Christianson, K and 7 others (2014) Dilatant till facilitates ice-stream flow in northeast Greenland. Earth Planet. Sci. Lett. 401, 5769
Dahl-Jensen, D and 6 others (1998) Past temperatures directly from the Greenland Ice Sheet. Science 282
Dahl-Jensen, D, Gundestrup, N, Gogineni, SP and Miller, H (2003) Basal melt at North GRIP modelled from borehole, ice-core and radio-echo sounder observations. Ann. Glaciol. 37, 207212
Dansgaard, W, Johnsen, SJ, Møller, J and Langway, CC (1969) One thousand centuries of climatic record from Camp Century on the Greenland Ice Sheet. Science 166, 377380
Dawes, PR (2009) Review of survey activities: the bedrock geology under the Inland Ice: the next major challenge for Greenland mapping. Geol. Surv. Denmark Greenland Bull. 17, 5760
Dowdeswell, JA and Evans, S (2004) Investigations of the form and flow of ice sheets and glaciers using radio-echo sounding. Rep. Prog. Phys. 67, 1821
Fahnestock, M, Abdalati, W, Joughin, I, Brozena, J and Gogineni, SP (2001) High geothermal heat flow, basal melt, and the origin of rapid ice flow in central Greenland. Science 294, 23382342
Fox Maule, C, Purucker, ME and Olsen, N (2009) Inferring magnetic crustal thickness and geothermal heat flux from crustal field models. Danish Climate Centre Report
Gogineni, S and 9 others (2001) Coherent radar ice sheet measurements over the Greenland Ice Sheet. J. Geophys. Res. 106(D24), 3376133772
Greve, R (1997) Application of a polythermal three-dimensional ice sheet model to the Greenland Ice Sheet: response to steady-state and transient climate scenarios. J. Clim. 10, 901918
Greve, R (2005) Relation of measured basal temperatures and the spatial distribution of the geothermal heat flux for the Greenland Ice Sheet. Ann. Glaciol. 42.1, 424432
Gundestrup, NS and Hansen, BL (1984) Bore-hole survey at Dye 3, south Greenland. J. Glaciol. 30, 282288
Hubbard, SS and 6 others (1997) Estimation of permeable pathways and water content using tomographic radar data. Leading Edge 16, 16231628
Jordan, TM and 7 others (2016) An ice-sheet-wide framework for englacial attenuation from ice-penetrating radar data. Cryosphere 10, 15471570
Jordan, TM and 6 others (2017) Self-affine subglacial roughness: consequences for radar scattering and basal water discrimination in northern Greenland. Cryosphere 11, 12471264
Layberry, RL and Bamber, JL (2001) A new ice thickness and bed data set for the Greenland Ice Sheet (2). J. Geophys. Res. 106, 3378133788
Livingstone, S, Clark, C, Woodward, J and Kingslake, J (2013) Potential subglacial lake locations and meltwater drainage pathways beneath the Antarctic and Greenland Ice Sheets. Cryosphere 7, 17211740. ISSN 1994–0424
MacGregor, JA and 5 others (2007) Modeling englacial radar attenuation at Siple Dome, West Antarctica, using ice chemistry and temperature data. J. Geophys. Res. 112, F03008
Macgregor, JA, Matsuoka, K, Waddington, ED, Winebrenner, DP and Pattyn, F (2012) Spatial variation of englacial radar attenuation: modeling approach and application to the Vostok flowline. J. Geophys. Res. 117, F03022
MacGregor, JA and 10 others (2015) Radar attenuation and temperature within the Greenland Ice Sheet. J. Geophys. Res. 120, 9831008
MacGregor, JA and 8 others (2016) A synthesis of the basal thermal state of the Greenland Ice Sheet. J. Geophys. Res. Earth Surf. 121, 13281350
Matsuoka, K (2011) Pitfalls in radar diagnosis of ice-sheet bed conditions: lessons from englacial attenuation models. Geophys. Res. Lett. 38, 15
Matsuoka, K, Morse, D and Raymond, CA (2010a) Estimating englacial radar attenuation using depth profiles of the returned power, central West Antarctica (2010). J. Geophys. Res. 115, F02012
Matsuoka, K, MacGregor, JA and Pattyn, F (2010b) Using englacial radar attenuation to better diagnose the subglacial environment: a review. In Proceedings Of the 13th International Conference on Ground Penetrating Radar (GPR), 21–25 June 2010, Lecce, Italy, doi: 10.1109/ICGPR.2010.5550161
Mouginot, J, Rignot, E, Scheuchl, B and Millan, R (2017) Comprehensive annual ice sheet velocity mapping using Landsat-8, Sentinel-1, and RADARSAT-2 data. Remote. Sens. (Basel) 9, 364
Oswald, GKA (1975) Investigation of sub-ice bedrock characteristics by radio-echo sounding. J. Glaciol. 15
Oswald, GKA and Gogineni, SP (2008) Recovery of subglacial water extent from Greenland radar survey data. J. Glaciol. 54
Oswald, GKA and Gogineni, SP (2012) Mapping basal melt under the northern Greenland Ice Sheet. IEEE Trans. Geosci. Remote Sens. 50, 585592
Oswald, GKA and de Robin, GQ (1973) Lakes beneath the Antarctic Ice Sheet. Nature 245, 251254
Palmer, SJ and 8 others (2013) Greenland subglacial lakes detected by radar. Geophys. Res. Lett. 40, 61546159
Petrunin, AG and 6 others (2013) Heat flux variations beneath central Greenland's ice due to anomalously thin lithosphere. Nat. Geosci. 6, 746750
Rogozhina, I and 6 others (2012) Effects of uncertainties in the geothermal heat flux distribution on the Greenland Ice Sheet: an assessment of existing heat flow models. J. Geophys. Res. 117, F02025
Rogozhina, I and 9 others (2016) Melting at the base of the Greenland Ice Sheet explained by Iceland hotspot history. Nat. Geosci. 9, 366369
Schroeder, DM, Blankenship, DD and Young, DA (2013) Evidence for a water system transition beneath Thwaites Glacier, West Antarctica. Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX 78758.
Seroussi, H and 5 others (2013) Dependence of century-scale projections of the Greenland Ice Sheet on its thermal regime. J. Glaciol. 59, 10241034
Shapiro, NM and Ritzwoller, MH (2004) Inferring surface heat flux distributions guided by a global seismic model: particular application to Antarctica. Earth Planet. Sci. Lett. 223, 213224
Siegert, MJ, Carter, S, Tabacco, I, Popov, S and Blankenship, DD (2005) A revised inventory of Antarctic subglacial lakes. Antarct. Sci. 17, 453460
Stearns, LA, Smith, BE and Hamilton, GS (2008) Increased flow speed on a large East Antarctic outlet glacier caused by subglacial floods. Nat. Geosci., 15. doi: 10.1038/ngeo356
Thomas, RH and PARCA Investigators, Program for Regional Climate Assessment (PARCA) (2001) Goals, key findings, and future directions. J. Geophys. Res. 106, 3369133705
Weertman, J (1968) Comparison between measured and theoretical temperature profiles of the Camp Century, Greenland, Borehole, 1968. J. Geophys. Res. 73
Wingham, DJ, Siegert, MJ, Shepherd, A and Muir, AS (2006) Rapid discharge connects Antarctic subglacial lakes. Nature 440
Zwally, HJ and Giovinetto, MB (2001) Balance mass flux and ice velocity across the equilibrium line in drainage systems of Greenland. J. Geophys. Res. 106, 3371733728

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