@article {152, title = {Rapid Submarine Melting Driven by Subglacial Discharge, LeConte Glacier, Alaska}, journal = {Geophysical Research Letters}, volume = {40}, year = {2013}, abstract = {We show that subglacial freshwater discharge is the principal process driving high rates of submarine melting at tidewater glaciers. This buoyant discharge draws in warm seawater, entraining it in a turbulent upwelling flow along the submarine face that melts glacier ice. To capture the effects of subglacial discharge on submarine melting, we conducted 4 days of hydrographic transects during late summer 2012 at LeConte Glacier, Alaska. A major rainstorm allowed us to document the influence of large changes in subglacial discharge. We found strong submarine melt fluxes that increased from 9.1 {\textpm} 1.0 to 16.8 {\textpm} 1.3 m d-1 (ice face equivalent frontal ablation) as a result of the rainstorm. With projected continued global warming and increased glacial runoff, our results highlight the direct impact that increases in subglacial discharge will have on tidewater outlet systems. These effects must be considered when modeling glacier response to future warming and increased runoff.}, keywords = {frontal ablation, submarine melting, tidewater glaciers}, issn = {1944-8007}, doi = {10.1002/grl.51011}, url = {http://dx.doi.org/10.1002/grl.51011}, author = {Roman J. Motyka and Dryer, W. P. and Jason M Amundson and Martin Truffer and Mark Fahnestock} } @article {153, title = {On the seasonal freshwater stratification in the proximity of fast-flowing tidewater outlet glaciers in a sub-Arctic sill fjord}, journal = {Journal of Geophysical Research: Oceans}, volume = {118}, year = {2013}, pages = {1382{\textendash}1395}, abstract = {The Greenland Ice Sheet releases large amounts of freshwater into the fjords around Greenland and many fjords are in direct contact with the ice sheet through tidewater outlet glaciers. Here we present the first seasonal hydrographic observations from the inner part of a sub-Arctic fjord, relatively close to and within 4{\textendash}50 km of a fast-flowing tidewater outlet glacier. This region is characterized by a dense glacial and sea ice cover. Freshwater from runoff, subglacial freshwater (SgFW) discharge, glacial, and sea ice melt are observed above 50{\textendash}90 m depth. During summer, SgFW and subsurface glacial melt mixed with ambient water are observed as a layered structure in the temperature profiles below the low-saline summer surface layer (<7 m). During winter, the upper water column is characterized by stepwise halo- and thermoclines formed by mixing between deeper layers and the surface layer influenced by ice melt. The warm (T > 1{\textdegree}C) intermediate water mass is a significant subsurface heat source for ice melt. We analyze the temperature and salinity profiles observed in late summer with a thermodynamic mixing model and determine the total freshwater content in the layer below the summer surface layer to be between 5\% and 11\%. The total freshwater contribution in this layer from melted glacial ice was estimated to be 1{\textendash}2\%, while the corresponding SgFW was estimated to be 3{\textendash}10\%. The winter measurements in the subsurface halocline layer showed a total freshwater content of about 1\% and no significant contribution from SgFW.}, keywords = {fjord, freshwater sources and their distribution, Greenland Ice Sheet, subglacial freshwater fraction model, subsurface heat sources for glacial ice melt, tidewater outlet glaciers}, issn = {2169-9291}, doi = {10.1002/jgrc.20134}, url = {http://dx.doi.org/10.1002/jgrc.20134}, author = {Mortensen, J. and Bendtsen, J. and Roman J. Motyka and Lennert, K. and Martin Truffer and Mark Fahnestock and Rysgaard, S.} } @article {123, title = {Outlet glacier response to forcing over hourly to interannual timescales, Jakobshavn Isbr{\ae}, Greenland}, journal = {Journal of Glaciology}, volume = {58}, year = {2012}, pages = {1212}, doi = {10.3189/2012JoG12J065}, author = {Podrasky, David and Martin Truffer and Mark Fahnestock and Jason M Amundson and Cassotto, Ryan and Ian Joughin} } @article {60, title = {Submarine melting of the 1985 Jakobshavn Isbr{\ae} floating tongue and the triggering of the current retreat}, journal = {Journal of Geophysical Research}, volume = {116}, year = {2011}, pages = {F01007}, doi = {10.1029/2009JF001632}, author = {Roman J. Motyka and Martin Truffer and Mark Fahnestock and Mortensen, J. and Rysgaard, S. and I M Howat} } @article {56, title = {Ice m{\'e}lange dynamics and implications for terminus stability, Jakobshavn Isbr{\ae}, Greenland}, journal = {Journal of Geophysical Research}, volume = {115}, year = {2010}, pages = {F01005}, doi = {10.1029/2009JF001405}, author = {Jason M Amundson and Mark Fahnestock and Martin Truffer and Brown, J. and M P L{\"u}thi and Roman J. Motyka} } @article {49, title = {Volume change of Jakobshavn Isbrae, West Greenland:: 198519972007}, journal = {Journal of Glaciology}, volume = {56}, year = {2010}, pages = {635{\textendash}646}, url = {http://openurl.ingenta.com/content/xref?genre=article\&issn=0022-1430\&volume=56\&issue=198\&spage=635}, author = {Roman J. Motyka and Mark Fahnestock and Martin Truffer} } @article {35, title = {Calving icebergs indicate a thick layer of temperate ice at the base of Jakobshavn Isbr{\ae}, Greenland}, journal = {Journal of Glaciology}, volume = {55}, year = {2009}, pages = {563{\textendash}566}, url = {http://openurl.ingenta.com/content/xref?genre=article\&issn=0022-1430\&volume=55\&issue=191\&spage=563}, author = {M P L{\"u}thi and Mark Fahnestock and Martin Truffer} } @article {28, title = {Continued evolution of Jakobshavn Isbrae following its rapid speedup}, journal = {J. geophys. Res}, volume = {113}, year = {2008}, pages = {F04006}, url = {http://www.agu.org/pubs/crossref/2008/2008JF001023.shtml}, author = {Ian Joughin and I M Howat and Mark Fahnestock and B ~E Smith and Krabill, W. and Alley, R.B. and Stern, H. and Martin Truffer} } @article {32, title = {Glacier, fjord, and seismic response to recent large calving events, Jakobshavn Isbr{\ae}, Greenland}, journal = {Geophysical Research Letters}, volume = {35}, year = {2008}, pages = {L22501}, url = {http://www.agu.org/pubs/crossref/2008/2008GL035281.shtml}, author = {Jason M Amundson and Martin Truffer and M P L{\"u}thi and Mark Fahnestock and West, M. and Roman J. Motyka} } @article {29, title = {Ice-front variation and tidewater behavior on Helheim and Kangerdlugssuaq Glaciers, Greenland}, journal = {Journal of Geophysical Research}, volume = {113}, year = {2008}, pages = {F01004}, url = {http://www.agu.org/pubs/crossref/2008/2007JF000837.shtml}, author = {Ian Joughin and I M Howat and Alley, R.B. and Ekstrom, G. and Mark Fahnestock and Moon, T. and Nettles, M. and Martin Truffer and Tsai, V.C.} } @article {3, title = {Rethinking ice sheet time scales}, journal = {Science}, volume = {315}, year = {2007}, pages = {1508{\textendash}1510}, doi = {10.1126/science.11404}, author = {Martin Truffer and Mark Fahnestock} }