Below-surface ice melt on the coastal Antarctic ice sheet

Liston, Glen E.; Winther, Jan‐Gunnar; Bruland, Oddbjørn; Elvehøy, Hallgeir; Sand, Knut

doi:10.1017/s0022143000001775

Cited by 99 publications

(178 citation statements)

References 25 publications

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“…Low-albedo blue ice 11,23 , nunataks and surface debris facilitate melting by increasing the absorption of solar energy 24 . Blue ice forms when snow is entirely removed by wind erosion 25 , sublimation or melt, often adjacent to nunataks 26 , because rugged terrain promotes high winds and lowalbedo rock increases air temperatures 27 .…”

mentioning

confidence: 99%

Widespread movement of meltwater onto and across Antarctic ice shelves

Kingslake

Ely

Das

et al. 2017

Nature

213

272

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Surface meltwater drains across ice sheets, forming melt ponds that can trigger ice-shelf collapse 1, 2 , acceleration of grounded ice flow and increased sea-level rise 3, 4, 5 . Numerical models of the Antarctic Ice Sheet that incorporate meltwater's impact on ice shelves, but ignore the movement of water across the ice surface, predict a metre of global sea-level rise this century 5 in response to atmospheric warming 6 . To understand the impact of water moving across the ice surface a broad quantification of surface meltwater and its drainage is needed. Yet, despite extensive research in Greenland 7, 8, 9, 10 and observations of individual drainage systems in Antarctica 10, 11, 12, 13, 14, 15, 16, 17, we have little understanding of Antarctic-wide surface hydrology or how it will evolve. Here we show widespread drainage of meltwater across the surface of the ice sheet through surface streams and ponds (hereafter 'surface drainage') as far south as 85° S and as high as 1,300 metres above sea level. Our findings are based on satellite imagery from 1973 onwards and aerial photography from 1947 onwards. Surface drainage has persisted for decades, transporting water up to 120 kilometres from grounded ice onto and across ice shelves, feeding vast melt ponds up to 80 kilometres long. Large-scale surface drainage could deliver water to areas of ice shelves vulnerable to collapse, as melt rates increase this century. While Antarctic surface melt ponds are relatively well documented on some ice shelves, we have discovered that ponds often form part of widespread, large-scale surface drainage systems. In a warming climate, enhanced surface drainage could accelerate future ice-mass loss from Antarctic, potentially via positive feedbacks between the extent of exposed rock, melting and thinning of the ice sheet.

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mentioning

confidence: 99%

Widespread movement of meltwater onto and across Antarctic ice shelves

Kingslake

Ely

Das

et al. 2017

Nature

213

272

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“…There was a strong negative correlation between albedo and surface temperature after 1 November, when surface temperature approached the melting point gradually; their correlation coefficients in 2010 and 2011 were −0.49 and −0.61, respectively. The albedo dependence on surface temperature is related to the fact surface properties change as surface temperature approaches 0 • C (Liston et al, 1999;Pirazzini, 2004). After removing the effects of snow thickness, the partial correlations of the albedo and surface temperature were −0.28 and −0.25 in 2010 and 2011, respectively. In contrast, the partial correlations of the albedo and snow thickness were still high (0.56 and 0.89).…”

Section: Evaluation Of Albedo Parameterizations In Climate Modelsmentioning

confidence: 99%

Albedo of coastal landfast sea ice in Prydz Bay, Antarctica: Observations and parameterization

et al. 2016

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The snow/sea-ice albedo was measured over coastal landfast sea ice in Prydz Bay, East Antarctica (off Zhongshan Station) during the austral spring and summer of 2010 and 2011. The variation of the observed albedo was a combination of a gradual seasonal transition from spring to summer and abrupt changes resulting from synoptic events, including snowfall, blowing snow, and overcast skies. The measured albedo ranged from 0.94 over thick fresh snow to 0.36 over melting sea ice. It was found that snow thickness was the most important factor influencing the albedo variation, while synoptic events and overcast skies could increase the albedo by about 0.18 and 0.06, respectively. The in-situ measured albedo and related physical parameters (e.g., snow thickness, ice thickness, surface temperature, and air temperature) were then used to evaluate four different snow/ice albedo parameterizations used in a variety of climate models. The parameterized albedos showed substantial discrepancies compared to the observed albedo, particularly during the summer melt period, even though more complex parameterizations yielded more realistic variations than simple ones. A modified parameterization was developed, which further considered synoptic events, cloud cover, and the local landfast sea-ice surface characteristics. The resulting parameterized albedo showed very good agreement with the observed albedo.

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“…The same field team also found multiple other meltwater features along the entire RBIS grounding zone. On the western RBIS, widespread shallow subsurface meltwater 14 was found in blue-ice areas above the grounding line (Fig. 1c).…”

mentioning

confidence: 99%