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The Cryosphere An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/tc-2017-107
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
17 Jul 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal The Cryosphere (TC).
Near surface meltwater storage in low-density bare ice of the Greenland ice sheet ablation zone
Matthew G. Cooper1, Laurence C. Smith1, Asa K. Rennermalm2, Clément Miège3, Lincoln H. Pitcher1, Johnny C. Ryan4, Kang Yang1, and Sarah Cooley1 1Department of Geography, University of California-Los Angeles, CA 90095, USA
2Department of Geography, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
3Department of Geography, University of Utah, Salt Lake City, Utah, USA
4Center for Glaciology, Department of Geography and Earth Sciences, Aberystwyth University, Aberystwyth, United Kingdom
Abstract. We document the density and hydrologic properties of bare, ablating ice in a mid-elevation (1215 m a.s.l.) supraglacial internally drained catchment near Kangerlussuaq, southwest Greenland. We find water saturated, low-density (474–725 kg m−3, μ = 688 kg m−3) ice to at least 1.1 m depth below the ice sheet surface. This near surface, low-density ice consists of alternating fractured porous ice and clear solid ice lenses, overlain by a thin (< 0.5 m), even lower density (326–555 kg m−3, μ = 455 kg m−3) unsaturated weathering crust. Ice-density data from 10 shallow (0.9–1.1 m) ice cores along an 800 m transect suggest an average 15–22 cm of liquid meltwater storage within this low-density ice. Water saturation of this ice is confirmed through measurable water levels (1–29 cm, μ = 10 cm) in 84 % of cryoconite holes and rapid infilling of 83 % of 1 m drilled holes sampled along the transect. Though preliminary, these findings are consistent with descriptions of shallow, depth-limited aquifers in weathering crusts of temperate and polythermal glaciers worldwide, and confirm the potential for substantial transient meltwater storage within porous low-density ice on the Greenland Ice Sheet ablation zone surface. A conservative estimate for the ~ 63 km2 catchment yields 0.010–0.014 km3 of liquid meltwater storage in near-surface, low-density ice. Further work is required to determine whether these findings are representative of broader areas of the Greenland Ice Sheet ablation zone, and to assess the implications for sub-seasonal surface mass balance calculations, surface lowering observations from airborne and satellite altimetry, and supraglacial runoff processes.

Citation: Cooper, M. G., Smith, L. C., Rennermalm, A. K., Miège, C., Pitcher, L. H., Ryan, J. C., Yang, K., and Cooley, S.: Near surface meltwater storage in low-density bare ice of the Greenland ice sheet ablation zone, The Cryosphere Discuss., https://doi.org/10.5194/tc-2017-107, in review, 2017.
Matthew G. Cooper et al.
Matthew G. Cooper et al.
Matthew G. Cooper et al.

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Short summary
We present measurements of ice density that show the melting bare-ice surface of the Greenland Ice Sheet study site is porous and saturated with meltwater. The data suggest up to 22 cm of meltwater is temporarily stored within porous, low-density ice. The findings imply meltwater drainage off the ice sheet surface is delayed, and that the ice sheet may be losing more mass in summer than would be suggested based solely on ice surface elevation change measurements.
We present measurements of ice density that show the melting bare-ice surface of the Greenland...
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