%0 Journal Article %J Journal of Glaciology %D 2015 %T Run-away thinning of the low elevation Yakutat Glacier and its sensitivity to climate change %A Truessel, Barbara %A Martin Truffer %A Regine Hock %A Roman Motyka %A Matthias Huss %A Jing Zhang %B Journal of Glaciology %V 61 %G eng %R 10.3189/2015JoG14J125 %0 Journal Article %J Bulletin of the American Meteorological Society %D 2013 %T Challenges to Understanding the Dynamic Response of Greenland's Marine Terminating Glaciers to Oceanic and Atmospheric Forcing %A Straneo, Fiammetta %A Heimbach, Patrick %A Sergienko, Olga %A Hamilton, Gordon %A Catania, Ginny %A Griffies, Stephen %A Hallberg, Robert %A Jenkins, Adrian %A Joughin, Ian %A Motyka, Roman %A Pfeffer, W. Tad %A Stephen F. Price %A Eric Rignot %A Scambos, Ted %A Martin Truffer %A Vieli, Andreas %B Bulletin of the American Meteorological Society %V 94 %P 1131 - 1144 %8 2013/08/01 %G eng %U http://dx.doi.org/10.1175/BAMS-D-12-00100.1 %N 8 %R 10.1175/BAMS-D-12-00100.1 %0 Journal Article %J The Cryosphere %D 2013 %T Changing basal conditions during the speed-up of Jakobshavn Isbræ, Greenland %A Habermann, M %A Martin Truffer %A Maxwell, D %B The Cryosphere %V 7 %P 1679–1692 %8 11/2013 %G eng %N 6 %0 Journal Article %J Geophysical Research Letters %D 2013 %T Rapid Submarine Melting Driven by Subglacial Discharge, LeConte Glacier, Alaska %A Roman J. Motyka %A Dryer, W. P. %A Jason M Amundson %A Martin Truffer %A Mark Fahnestock %K frontal ablation %K submarine melting %K tidewater glaciers %X 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 ± 1.0 to 16.8 ± 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. %B Geophysical Research Letters %V 40 %G eng %U http://dx.doi.org/10.1002/grl.51011 %R 10.1002/grl.51011 %0 Journal Article %J Journal of Geophysical Research: Oceans %D 2013 %T On the seasonal freshwater stratification in the proximity of fast-flowing tidewater outlet glaciers in a sub-Arctic sill fjord %A Mortensen, J. %A Bendtsen, J. %A Roman J. Motyka %A Lennert, K. %A Martin Truffer %A Mark Fahnestock %A Rysgaard, S. %K fjord %K freshwater sources and their distribution %K Greenland Ice Sheet %K subglacial freshwater fraction model %K subsurface heat sources for glacial ice melt %K tidewater outlet glaciers %X 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 4–50 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 50–90 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°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 1–2%, while the corresponding SgFW was estimated to be 3–10%. The winter measurements in the subsurface halocline layer showed a total freshwater content of about 1% and no significant contribution from SgFW. %B Journal of Geophysical Research: Oceans %V 118 %P 1382–1395 %G eng %U http://dx.doi.org/10.1002/jgrc.20134 %R 10.1002/jgrc.20134 %0 Journal Article %J Journal of Glaciology %D 2012 %T Outlet glacier response to forcing over hourly to interannual timescales, Jakobshavn Isbræ, Greenland %A Podrasky, David %A Martin Truffer %A Mark Fahnestock %A Jason M Amundson %A Cassotto, Ryan %A Ian Joughin %B Journal of Glaciology %V 58 %P 1212 %G eng %R 10.3189/2012JoG12J065 %0 Journal Article %J Journal of Glaciology %D 2012 %T Reconstruction of basal properties in ice sheets using iterative inverse methods %A Habermann, M. %A Maxwell, D. %A Martin Truffer %B Journal of Glaciology %V 58 %P 795–807 %G eng %0 Journal Article %J Journal of Glaciology %D 2012 %T Using surface velocities to calculate ice thickness and bed topography: a case study at Columbia Glacier, Alaska, USA %A R  W McNabb %A Regine Hock %A Shad OʼNeel %A L  A Rasmussen %A Ahn, Y. %A M Braun %A H Conway %A Herreid, S. %A Ian Joughin %A W. Tad Pfeffer %A B  E Smith %A Martin Truffer %B Journal of Glaciology %V 58 %P 1151-1164 %G eng %N 212 %R 10.3189/2012JoG11J249 %0 Journal Article %J Journal of Glaciology %D 2011 %T From ice-shelf tributary to tidewater glacier: continued rapid recession, acceleration and thinning of Rohss Glacier following the 1995 collapse of the Prince Gustav Ice Shelf, Antarctic Peninsula %A Glasser, NF %A Scambos, TA %A Bohlander, J. %A Martin Truffer %A Erin C Pettit %A Davies, BJ %B Journal of Glaciology %V 57 %P 397–406 %G eng %U http://openurl.ingenta.com/content/xref?genre=article&issn=0022-1430&volume=57&issue=203&spage=397 %R 10.3189/002214311796905578 %0 Journal Article %J Journal of Geophysical Research %D 2011 %T Submarine melting of the 1985 Jakobshavn Isbræ floating tongue and the triggering of the current retreat %A Roman J. Motyka %A Martin Truffer %A Mark Fahnestock %A Mortensen, J. %A Rysgaard, S. %A I M Howat %B Journal of Geophysical Research %V 116 %P F01007 %G eng %R 10.1029/2009JF001632 %0 Journal Article %J Geology %D 2010 %T Glacier microseismicity %A West, M. %A Chris F. Larsen %A Martin Truffer %A Shad OʼNeel %A LeBlanc, Laura %X We present a framework for interpreting small glacier seismic events based on data collected near the center of Bering Glacier, Alaska, in spring 2007. We find extremely high microseismicity rates (as many as tens of events per minute) occurring largely within a few kilometers of the receivers. A high-frequency class of seismicity is distinguished by dominant frequencies of 20–35 Hz and impulsive arrivals. A low-frequency class has dominant frequencies of 6–15 Hz, emergent onsets, and longer, more monotonic codas. A bimodal distribution of 160,000 seismic events over two months demonstrates that the classes represent two distinct populations. This is further supported by the presence of hybrid waveforms that contain elements of both event types. The high-low-hybrid paradigm is well established in volcano seismology and is demonstrated by a comparison to earthquakes from Augustine Volcano. We build on these parallels to suggest that fluid-induced resonance is likely responsible for the low-frequency glacier events and that the hybrid glacier events may be caused by the rush of water into newly opening pathways. %B Geology %V 38 %P 319-322 %G eng %U http://geology.gsapubs.org/content/38/4/319.abstract %R 10.1130/G30606.1 %0 Journal Article %J Journal of Geophysical Research %D 2010 %T Ice mélange dynamics and implications for terminus stability, Jakobshavn Isbræ, Greenland %A Jason M Amundson %A Mark Fahnestock %A Martin Truffer %A Brown, J. %A M P Lüthi %A Roman J. Motyka %B Journal of Geophysical Research %V 115 %P F01005 %G eng %R 10.1029/2009JF001405 %0 Journal Article %J Journal of Glaciology %D 2010 %T A unifying framework for iceberg-calving models %A Jason M Amundson %A Martin Truffer %B Journal of Glaciology %V 56 %P 822–830 %G eng %U http://openurl.ingenta.com/content/xref?genre=article&issn=0022-1430&volume=56&issue=199&spage=822 %0 Journal Article %J Journal of Glaciology %D 2010 %T Volume change of Jakobshavn Isbrae, West Greenland:: 198519972007 %A Roman J. Motyka %A Mark Fahnestock %A Martin Truffer %B Journal of Glaciology %V 56 %P 635–646 %G eng %U http://openurl.ingenta.com/content/xref?genre=article&issn=0022-1430&volume=56&issue=198&spage=635 %0 Journal Article %J Journal of Glaciology %D 2009 %T Calving icebergs indicate a thick layer of temperate ice at the base of Jakobshavn Isbræ, Greenland %A M P Lüthi %A Mark Fahnestock %A Martin Truffer %B Journal of Glaciology %V 55 %P 563–566 %G eng %U http://openurl.ingenta.com/content/xref?genre=article&issn=0022-1430&volume=55&issue=191&spage=563 %0 Journal Article %J Journal of Inverse and Ill-posed Problems %D 2009 %T Iterative methods for solving a nonlinear boundary inverse problem in glaciology %A Avdonin, S. %A Kozlov, V. %A Maxwell, D. %A Martin Truffer %B Journal of Inverse and Ill-posed Problems %V 17 %P 239–258 %G eng %U http://www.reference-global.com/doi/abs/10.1515/JIIP.2 %0 Journal Article %J Journal of Glaciology %D 2009 %T A method to estimate the ice volume and ice-thickness distribution of alpine glaciers %A Farinotti, D. %A Huss, M. %A Bauder, A. %A Funk, M. %A Martin Truffer %B Journal of Glaciology %V 55 %P 422–430 %G eng %U http://openurl.ingenta.com/content/xref?genre=article&issn=0022-1430&volume=55&issue=191&spage=422 %0 Journal Article %J Journal of Glaciology %D 2009 %T Terminus dynamics at an advancing glacier: Taku Glacier, Alaska %A Martin Truffer %A Roman J. Motyka %A Hekkers, M. %A I M Howat %A King, M.A. %B Journal of Glaciology %V 55 %P 1052–1060 %G eng %U http://openurl.ingenta.com/content/xref?genre=article&issn=0022-1430&volume=55&issue=194&spage=1052 %0 Journal Article %J J. geophys. Res %D 2008 %T Continued evolution of Jakobshavn Isbrae following its rapid speedup %A Ian Joughin %A I M Howat %A Mark Fahnestock %A B  E Smith %A Krabill, W. %A Alley, R.B. %A Stern, H. %A Martin Truffer %B J. geophys. Res %V 113 %P F04006 %G eng %U http://www.agu.org/pubs/crossref/2008/2008JF001023.shtml %0 Journal Article %J Journal of Glaciology %D 2008 %T Correspondence: Another surge of Variegated Glacier, Alaska, USA, 2003/04 %A Harrison, W. %A Roman J. Motyka %A Martin Truffer %B Journal of Glaciology %V 54 %P 192-200 %G eng %U http://www.ingentaconnect.com/content/igsoc/jog/2008/00000054/00000184/art00019 %R doi:10.3189/002214308784409134 %0 Journal Article %J Geophysical Research Letters %D 2008 %T Glacier, fjord, and seismic response to recent large calving events, Jakobshavn Isbræ, Greenland %A Jason M Amundson %A Martin Truffer %A M P Lüthi %A Mark Fahnestock %A West, M. %A Roman J. Motyka %B Geophysical Research Letters %V 35 %P L22501 %G eng %U http://www.agu.org/pubs/crossref/2008/2008GL035281.shtml %0 Journal Article %J Arctic, Antarctic, and Alpine Research %D 2008 %T Glacier Recession on Heard Island, Southern Indian Ocean %A Thost, D.E. %A Martin Truffer %B Arctic, Antarctic, and Alpine Research %V 40 %P 199–214 %G eng %U http://www.bioone.org/doi/abs/10.1657/1523-0430(06-084)%5BTHOST%5D2.0.CO;2 %0 Journal Article %J Journal of Geophysical Research %D 2008 %T Ice-front variation and tidewater behavior on Helheim and Kangerdlugssuaq Glaciers, Greenland %A Ian Joughin %A I M Howat %A Alley, R.B. %A Ekstrom, G. %A Mark Fahnestock %A Moon, T. %A Nettles, M. %A Martin Truffer %A Tsai, V.C. %B Journal of Geophysical Research %V 113 %P F01004 %G eng %U http://www.agu.org/pubs/crossref/2008/2007JF000837.shtml %0 Journal Article %J Journal of Glaciology %D 2008 %T An iterative scheme for determining glacier velocities and stresses %A Maxwell, D. %A Martin Truffer %A Avdonin, S. %A Stuefer, M. %B Journal of Glaciology %V 54 %P 888–898 %G eng %U http://openurl.ingenta.com/content/xref?genre=article&issn=0022-1430&volume=54&issue=188&spage=888 %0 Journal Article %J Journal of Glaciology %D 2008 %T Seasonal fluctuations in the advance of a tidewater glacier and potential causes: Hubbard Glacier, Alaska, USA %A Ritchie, J.B. %A C S Lingle %A Roman J. Motyka %A Martin Truffer %B Journal of Glaciology %V 54 %P 401–411 %G eng %U http://openurl.ingenta.com/content/xref?genre=article&issn=0022-1430&volume=54&issue=186&spage=401 %0 Journal Article %J Journal of Glaciology %D 2008 %T Seasonality of snow accumulation at Mount Wrangell, Alaska, USA %A Kanamori, S. %A Benson, C.S. %A Martin Truffer %A Matoba, S. %A Solie, D.J. %A Shiraiwa, T. %B Journal of Glaciology %V 54 %P 273–278 %G eng %U http://www.ingentaconnect.com/content/igsoc/jog/2008/00000054/00000185/art00008 %0 Journal Article %J Journal of Glaciology %D 2007 %T Flotation and retreat of a lake-calving terminus, Mendenhall Glacier, southeast Alaska, USA %A Boyce, E.S. %A Roman J. Motyka %A Martin Truffer %B Journal of Glaciology %V 53 %P 211–224 %G eng %0 Journal Article %J Annals of Glaciology %D 2007 %T Glaciervolcano interactions in the North Crater of Mt Wrangell, Alaska %A Benson, C.S. %A Roman J. Motyka %A McNUTT, S. %A M P Lüthi %A Martin Truffer %B Annals of Glaciology %V 45 %P 48–57 %G eng %0 Journal Article %J Journal of geophysical research %D 2007 %T Hubbard Glacier, Alaska: 2002 closure and outburst of Russell Fjord and postflood conditions at Gilbert Point %A Roman J. Motyka %A Martin Truffer %B Journal of geophysical research %V 112 %P F02004 %G eng %0 Journal Article %J Science %D 2007 %T Rethinking ice sheet time scales %A Martin Truffer %A Mark Fahnestock %B Science %V 315 %P 1508–1510 %G eng %R 10.1126/science.11404