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- Title
Meltwater storage in low-density near-surface bare ice in the Greenland ice sheet ablation zone.
- Authors
Cooper, Matthew G.; Smith, Laurence C.; Rennermalm, Asa K.; Miège, Clément; Pitcher, Lincoln H.; Ryan, Jonathan C.; Yang, Kang; Cooley, Sarah W.
- Abstract
We document the density and hydrologic properties of bare, ablating ice in a mid-elevation (1215ma.s.l.) supraglacial internally drained catchment in the Kangerlussuaq sector of the western Greenland ice sheet. We find lowdensity (0.43-0.91 g cm3, μ= 0:69 g cm3/ ice to at least 1.1m depth below the ice sheet surface. This near-surface, low-density ice consists of alternating layers of watersaturated, porous ice and clear solid ice lenses, overlain by a thin (< 0.5 m), even lower density (0.33-0.56 g cm3, μ= 0:45 g cm3/ unsaturated weathering crust. Ice density data from 10 shallow (0.9-1.1 m) ice cores along an 800m transect suggest an average 14-18 cm of specific meltwater storage within this low-density ice. Water saturation of this ice is confirmed through measurable water levels (1-29 cm above hole bottoms, μ= 10 cm) in 84% of cryoconite holes and rapid refilling of 83% of 1m drilled holes sampled along the transect. These findings are consistent with descriptions of shallow, depth-limited aquifers on the weathered surface of 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 km3 supraglacial catchment yields 0.009-0.012 km3 of liquid meltwater storage in nearsurface, porous ice. Further work is required to determine if these findings are representative of broader areas of the Greenland ice sheet ablation zone, and to assess the implications for sub-seasonal mass balance processes, surface lowering observations from airborne and satellite altimetry, and supraglacial runoff processes.
- Subjects
MELTWATER; ICE sheets; ABLATION (Glaciology); GLACIERS; WATER storage
- Publication
Cryosphere, 2018, Vol 12, Issue 3, p955
- ISSN
1994-0416
- Publication type
Article
- DOI
10.5194/tc-12-955-2018