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Woods Hole Oceanographic Institution

Sarah B. Das

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Publications
»Antarctic meltwater flux, GRL, 2013
»Tropical Pacific influence on W. Antarctic marine aerosols, J. Climate, 2013
»Thwaites Glacier, Antarctica accumulation, GRL, 2013
»ACCMIP multi-model global nitrogen and sulfur deposition dataset, ACP, 2013
»Influence of ice sheet geometry and supraglacial lakes on seasonal ice flow, TC, 2013
»Greenland Iron Export, Nature Geosc, 2013
»Greenland Organic Carbon Export, GCA, 2013
»Amundsen Coast Sea Ice and Polynya Variability, JGR, 2013
»Ice Core 10Be Records, EPSL, 2012
»Antarctic Ice Sheet Surface Melting, JGR, 2012
»Greenland discharge isotope mixing model, J. Glac., 2011
»Future Science Opportunities in Antarctica and the Southern Ocean, NRC Report, 2011
»Greenland Ice Sheet DOM, GCA, 2010
»Ice Sheet Hydrofracture and Water-transport Model, GRL, 2009
»Greenland Supraglacial Lake Drainage, Science, 2008
»Greenland Seasonal Speedup, Science, 2008
»West Antarctica Holocene Climate, JGR, 2008
»Greenland Accumulation, J. Climate, 2006
»Melt Layer Formation, J. Glac, 2005
»Whillans Ice Stream Deceleration, GRL, 2005
»Siple Dome Temperature Variability, Annals Glac., 2002
»Patagonian Icefield SAR, JGR, 1996


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Das, S.B. and R.B. Alley, Characterization and formation of melt-layers in polar snow: Observations and experiments from West Antarctica, Journal of Glaciology, v51, 307-312, 2005

Surface melting rarely occurs across most of the Antarctic Ice Sheet away from the warmer coastal regions. Nonetheless isolated melt features are found to be preserved in the firn and ice in response to infrequent and short-lived melting events. An understanding of the formation and occurrence of these unique melt-layers will help us interpret records of past melt occurrence from polar ice cores, such as the Siple Dome ice core record from West Antarctica. A search in the near-surface firn in West Antarctica found that melt features are extremely rare, and consist of horizontal, laterally continuous, one to few mm thick, ice layers with few air bubbles. The melt-layers found date from the 1992/93 and 1991/92 summers. Field experiments done to investigate changes in stratigraphy taking place during melt events reproduced melt features as seen in the natural stratigraphy. Melting conditions of varying intensity were created by passively heating the near-surface air for varying lengths of time inside a plexi-glass hotbox. Melt-layers formed due entirely to preferential flow and subsequent refreezing of melt water from the surface into near-surface, fine-grained, crust layers. Continuous melt-layers were formed experimentally when positive-degree-day values exceeded 1?C-day, a value corresponding well with air temperature records from automatic weather station sites where melt-layers formed in the recent past.

FILE » DasAlley2005



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