TY - JOUR T1 - Seasonal and interannual variations in ice melange and its impact on terminus stability, Jakobshavn Isbræ, Greenland JF - Journal of Glaciology Y1 - 2015 A1 - Cassotto, Ryan A1 - Fahnestock, Mark A1 - Amundson, Jason M. A1 - Truffer, Martin A1 - Joughin, Ian KW - arctic glaciology KW - calving KW - ice KW - ocean interactions KW - Remote sensing KW - sea-ice dynamics VL - 61 ER - TY - JOUR T1 - Challenges to Understanding the Dynamic Response of Greenland's Marine Terminating Glaciers to Oceanic and Atmospheric Forcing JF - Bulletin of the American Meteorological Society Y1 - 2013 A1 - Straneo, Fiammetta A1 - Heimbach, Patrick A1 - Sergienko, Olga A1 - Hamilton, Gordon A1 - Catania, Ginny A1 - Griffies, Stephen A1 - Hallberg, Robert A1 - Jenkins, Adrian A1 - Joughin, Ian A1 - Motyka, Roman A1 - Pfeffer, W. Tad A1 - Stephen F. Price A1 - Eric Rignot A1 - Scambos, Ted A1 - Martin Truffer A1 - Vieli, Andreas VL - 94 UR - http://dx.doi.org/10.1175/BAMS-D-12-00100.1 IS - 8 ER - TY - JOUR T1 - Outlet glacier response to forcing over hourly to interannual timescales, Jakobshavn Isbræ, Greenland JF - J. Glaciol. Y1 - 2012 A1 - Podrasky, David A1 - Truffer, Martin A1 - Fahnestock, Mark A1 - Amundson, Jason M. A1 - Cassotto, Ryan A1 - Joughin, Ian VL - 58 UR - http://openurl.ingenta.com/content/xref?genre=article{&}issn=0022-1430{&}volume=58{&}issue=212{&}spage=1212 ER - TY - JOUR T1 - Seasonal to decadal scale variations in the surface velocity of Jakobshavn Isbrae, Greenland: Observation and model-based analysis JF - J. Geophys. Res. Y1 - 2012 A1 - Joughin, Ian A1 - Smith, B. E. A1 - Howat, I. M. A1 - Floricioiu, Dana A1 - Alley, Richard B. A1 - Truffer, M. A1 - Fahnestock, M.A. KW - glacier KW - glaciology KW - ice stream VL - 117 UR - http://www.agu.org/pubs/crossref/2012/2011JF002110.shtml ER - TY - JOUR T1 - Ice-front variation and tidewater behavior on Helheim and Kangerdlugssuaq Glaciers, Greenland JF - Journal of Geophysical Research: Earth Surface Y1 - 2008 A1 - Joughin, Ian A1 - Howat, Ian A1 - Alley, Richard B. A1 - Ekstrom, Goran A1 - Fahnestock, Mark A1 - Moon, Twila A1 - Nettles, Meredith A1 - Truffer, Martin A1 - Tsai, Victor C. AB - We used satellite images to examine the calving behavior ofHelheim and Kangerdlugssuaq Glaciers, Greenland, from 2001 to 2006, a period in which they retreated and speed up. These data show that many large iceberge-calving episodes coincided with teleseismically detected glacial erthquakes, suggesting that calving-related processes are the source of seismicity. For each of several events for which we hace observations, the ice front calved back to a large, pre-existing rift. These refits form where the ice has thinned to near flotation as the ice front retreats down back side of a bathymetric high, which agrees well with earlier theoretical predictions. In adition to recent retreat in a period of high temperature, analysis of several images shows that Helhaim retreated in the 20th Century during a warmer period and then re-adcanced during a subsequent cooler period. This apparent sensitivity to waming suggests that higher temperatures may promote an initial retread off a bathymetric high that is then sustained by tidewater dynamics as the ice front retreats into depper water. The cycle of frontal advance and retreat in less than a century indicates that tidewater glaciers in Greenland can advance rapidly. Greenland's larger resorvoir of inland ice and conditions that favor the formation of ice shelves likely contribute to the rapid rates of advance. VL - 113 SN - 0148-0227 UR - http://www.agu.org/pubs/crossref/2008/2007JF000837.shtml ER - TY - JOUR T1 - Large fluctuations in speed on Greenland's Jakobshavn Isbrae glacier. JF - Nature Y1 - 2004 A1 - Joughin, Ian A1 - Abdalati, Waleed A1 - Fahnestock, Mark AB - It is important to understand recent changes in the velocity of Greenland glaciers because the mass balance of the Greenland Ice Sheet is partly determined by the flow rates of these outlets. Jakobshavn Isbrae is Greenland's largest outlet glacier, draining about 6.5 per cent of the ice-sheet area, and it has been surveyed repeatedly since 1991 (ref. 2). Here we use remote sensing data to measure the velocity of Jakobshavn Isbrae between 1992 and 2003. We detect large variability of the velocity over time, including a slowing down from 6,700 m yr(-1) in 1985 to 5,700 m yr(-1) in 1992, and a subsequent speeding up to 9,400 m yr(-1) by 2000 and 12,600 m yr(-1) in 2003. These changes are consistent with earlier evidence for thickening of the glacier in the early 1990s and rapid thinning thereafter. Our observations indicate that fast-flowing glaciers can significantly alter ice discharge at sub-decadal timescales, with at least a potential to respond rapidly to a changing climate. VL - 432 SN - 0028-0836 ER - TY - JOUR T1 - High geothermal heat flow, Basal melt, and the origin of rapid ice flow in central Greenland. JF - Science (New York, N.Y.) Y1 - 2001 A1 - Fahnestock, M A1 - Abdalati, W A1 - Joughin, Ian A1 - Brozena, J A1 - Gogineni, P AB - Age-depth relations from internal layering reveal a large region of rapid basal melting in Greenland. Melt is localized at the onset of rapid ice flow in the large ice stream that drains north off the summit dome and other areas in the northeast quadrant of the ice sheet. Locally, high melt rates indicate geothermal fluxes 15 to 30 times continental background. The southern limit of melt coincides with magnetic anomalies and topography that suggest a volcanic origin. VL - 294 UR - http://www.ncbi.nlm.nih.gov/pubmed/11743197 ER -