Woods Hole Oceanographic Institution

Sarah B. Das

»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

M.P. Bhatia, S.B. Das, E.B. Kujawinski, P. Henderson, A. Burke, and M.A.Charette, Seasonal evolution of water contributions to discharge from a Greenland outlet glacier: Insight from a new isotope-mixing model, J. Glaciology, v.57(205), 929-941, 2011

The Greenland ice sheet (GrIS) subglacial hydrological system may undergo a seasonal evolution, with significant geophysical and biogeochemical implications. We present results from a new isotope mixing model to quantify the relative contributions of surface snow, glacial ice, and delayed flow to the bulk meltwater discharge from a small (~5-km2) land-terminating GrIS outlet glacier during melt onset (May) and at peak melt (July). We use radioactive (radon-222) and stable isotopes (oxygen-18, deuterium) to differentiate the source-water contributions. Atmospherically-derived beryllium-7 further constrains meltwater transit time from the glacier surface to the ice margin.  We show that (i) radon-222 is a promising tracer for glacial waters stored at the bed and (ii) a quantitative chemical mixing model can be constructed by combining radon-222 and the stable water isotopes. Applying this model to the bulk subglacial outflow from our study area, we find a constant delayed flow (stored) component from melt onset through peak melt. This component is diluted first by snow-melt and then by increasing glacial ice-melt as the season progresses. Results from this pilot study are consistent with the hypothesis that subglacial drainage beneath land-terminating sections of the GrIS undergoes a seasonal evolution from a distributed system to a channelized one.

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