01664nas a2200217 4500008004100000022001400041024001300055245008400068210006900152490000700221520100800228653002101236653002201257653002301279100002201302700001801324700002301342700002001365700002101385856004001406 2013 eng d a1944-8007 aGRL5101100aRapid Submarine Melting Driven by Subglacial Discharge, LeConte Glacier, Alaska0 aRapid Submarine Melting Driven by Subglacial Discharge LeConte G0 v403 aWe 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.10afrontal ablation10asubmarine melting10atidewater glaciers1 aMotyka, Roman, J.1 aDryer, W., P.1 aAmundson, Jason, M1 aTruffer, Martin1 aFahnestock, Mark uhttp://dx.doi.org/10.1002/grl.5101102495nas a2200277 4500008004100000022001400041245013200055210006900187300001600256490000800272520156700280653001001847653004601857653002401903653004101927653004901968653003002017100001702047700001702064700002202081700001602103700002002119700002102139700001602160856004102176 2013 eng d a2169-929100aOn the seasonal freshwater stratification in the proximity of fast-flowing tidewater outlet glaciers in a sub-Arctic sill fjord0 aseasonal freshwater stratification in the proximity of fastflowi a1382–13950 v1183 aThe 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.10afjord10afreshwater sources and their distribution10aGreenland Ice Sheet10asubglacial freshwater fraction model10asubsurface heat sources for glacial ice melt10atidewater outlet glaciers1 aMortensen, J1 aBendtsen, J.1 aMotyka, Roman, J.1 aLennert, K.1 aTruffer, Martin1 aFahnestock, Mark1 aRysgaard, S uhttp://dx.doi.org/10.1002/jgrc.2013400666nas a2200217 4500008004100000245010600041210006900147300001100216490000800227100001800235700001300253700001100266700001400277700002900291700002200320700001200342700001600354700001300370700002200383856004300405 2012 eng d00aGravity and uplift rates observed in southeast Alaska and their comparison with GIA model predictions0 aGravity and uplift rates observed in southeast Alaska and their aB014010 v1171 aSato, Tatsuru1 aMiura, S1 aSun, W1 aSugano, T1 aFreymueller, Jeffrey, T.1 aLarsen, Chris, F.1 aOhta, Y1 aFujimoto, H1 aInazu, D1 aMotyka, Roman, J. uhttps://glaciers.gi.alaska.edu/node/5902143nas a2200193 4500008004100000022001400041245006400055210006200119300001400181490000700195520159900202653001201801653001301813100001701826700001801843700002201861700002301883856004301906 2011 eng d a2324-925000aA complex relationship between calving glaciers and climate0 acomplex relationship between calving glaciers and climate a305–3060 v923 aMany terrestrial glaciers are sensitive indicators of past and present climate change as atmospheric temperature and snowfall modulate glacier volume. However, climate interpretations based on glacier behavior require careful selection of representative glaciers, as was recently pointed out for surging and debris-covered glaciers, whose behavior often defies regional glacier response to climate [Yde and Paasche, 2010]. Tidewater calving glaciers (TWGs)—mountain glaciers whose termini reach the sea and are generally grounded on the seafloor—also fall into the category of non-representative glaciers because the regional-scale asynchronous behavior of these glaciers clouds their complex relationship with climate. TWGs span the globe; they can be found both fringing ice sheets and in high-latitude regions of each hemisphere. TWGs are known to exhibit cyclic behavior, characterized by slow advance and rapid, unstable retreat, largely independent of short-term climate forcing. This so-called TWG cycle, first described by Post [1975], provides a solid foundation upon which modern investigations of TWG stability are built. Scientific understanding has developed rapidly as a result of the initial recognition of their asynchronous cyclicity, rendering greater insight into the hierarchy of processes controlling regional behavior. This has improved the descriptions of the strong dynamic feedbacks present during retreat, the role of the ocean in TWG dynamics, and the similarities and differences between TWG and ice sheet outlet glaciers that can often support floating tongues.10aclimate10aglaciers1 aPost, Austin1 aOʼNeel, Shad1 aMotyka, Roman, J.1 aStreveler, Gregory uhttp://dx.doi.org/10.1029/2011EO37000101820nas a2200265 4500008004100000022001400041245007600055210006900131300001400200490000700214520106100221653001401282653001401296653001701310653001301327100002001340700002001360700002201380700002101402700002101423700002201444700002101466700002401487856004301511 2011 eng d a1944-800700aAn increase in crevasse extent, West Greenland: Hydrologic implications0 aincrease in crevasse extent West Greenland Hydrologic implicatio an/a–n/a0 v383 aWe compare high-resolution 1985 and 2009 imagery to assess changes in crevasse extent in the Sermeq Avannarleq ablation zone, West Greenland. The area occupied by crevasses >2 m wide significantly increased (13 ± 4%) over the 24-year period. This increase consists of an expansion of existing crevasse fields, and is accompanied by widespread changes in crevasse orientation (up to 45°). We suggest that a combination of ice sheet thinning and steepening are responsible for the increase in crevasse extent. We examine the potential impact of this change on the hydrology of the ice sheet. We provide a first-order demonstration that moulin-type drainage is more efficient in transferring meltwater fluctuations to the subglacial system than crevasse-type drainage. As enhanced basal sliding is associated with meltwater “pulses”, an increase in crevasse extent can therefore be expected to result in a net decrease in basal sliding sensitivity. An increase in crevasse extent may also accelerate cryo-hydrologic warming and enhance surface ablation.10acrevasses10aGreenland10amass balance10avelocity1 aColgan, William1 aSteffen, Konrad1 aMcLamb, W., Scott1 aAbdalati, Waleed1 aRajaram, Harihar1 aMotyka, Roman, J.1 aPhillips, Thomas1 aAnderson, Robert, S uhttp://dx.doi.org/10.1029/2011GL04849100629nas a2200193 4500008004100000245011900041210006900160300001200229490000800241100001800249700002200267700001300289700001200302700001600314700001100330700002200341700002900363856004300392 2011 eng d00aReevaluation of the viscoelastic and elastic responses to the past and present-day ice changes in Southeast Alaska0 aReevaluation of the viscoelastic and elastic responses to the pa a79–880 v5111 aSato, Tatsuru1 aLarsen, Chris, F.1 aMiura, S1 aOhta, Y1 aFujimoto, H1 aSun, W1 aMotyka, Roman, J.1 aFreymueller, Jeffrey, T. uhttps://glaciers.gi.alaska.edu/node/4600564nas a2200169 4500008004100000245011000041210007000151300001100221490000800232100002200240700002000262700002100282700001700303700001600320700001500336856004300351 2011 eng d00aSubmarine melting of the 1985 Jakobshavn Isbræ floating tongue and the triggering of the current retreat0 aSubmarine melting of the 1985 Jakobshavn Isbræ floating tongue a aF010070 v1161 aMotyka, Roman, J.1 aTruffer, Martin1 aFahnestock, Mark1 aMortensen, J1 aRysgaard, S1 aHowat, I M uhttps://glaciers.gi.alaska.edu/node/6000554nas a2200169 4500008004100000245009600041210007000137300001100207490000800218100002300226700002100249700002000270700001300290700001600303700002200319856004300341 2010 eng d00aIce mélange dynamics and implications for terminus stability, Jakobshavn Isbræ, Greenland0 aIce mélange dynamics and implications for terminus stability Jak aF010050 v1151 aAmundson, Jason, M1 aFahnestock, Mark1 aTruffer, Martin1 aBrown, J1 aLüthi, M P1 aMotyka, Roman, J. uhttps://glaciers.gi.alaska.edu/node/5600539nas a2200145 4500008004100000245013100041210006900172300001100241490000800252100001700260700002200277700002900299700002200328856004300350 2010 eng d00aTectonic block motion and glacial isostatic adjustment in southeast Alaska and adjacent Canada constrained by GPS measurements0 aTectonic block motion and glacial isostatic adjustment in southe aB094070 v1151 aElliott, J L1 aLarsen, Chris, F.1 aFreymueller, Jeffrey, T.1 aMotyka, Roman, J. uhttps://glaciers.gi.alaska.edu/node/5300499nas a2200133 4500008004100000245007000041210006700111300001400178490000700192100002200199700002100221700002000242856010300262 2010 eng d00aVolume change of Jakobshavn Isbrae, West Greenland:: 1985199720070 aVolume change of Jakobshavn Isbrae West Greenland 198519972007 a635–6460 v561 aMotyka, Roman, J.1 aFahnestock, Mark1 aTruffer, Martin uhttp://openurl.ingenta.com/content/xref?genre=article&issn=0022-1430&volume=56&issue=198&spage=63500546nas a2200157 4500008004100000245006800041210006600109300001600175490000700191100002000198700002200218700001500240700001500255700001400270856010400284 2009 eng d00aTerminus dynamics at an advancing glacier: Taku Glacier, Alaska0 aTerminus dynamics at an advancing glacier Taku Glacier Alaska a1052–10600 v551 aTruffer, Martin1 aMotyka, Roman, J.1 aHekkers, M1 aHowat, I M1 aKing, M A uhttp://openurl.ingenta.com/content/xref?genre=article&issn=0022-1430&volume=55&issue=194&spage=105200483nas a2200133 4500008004100000245007800041210006900119300001200188490000700200100001600207700002200223700002000245856008400265 2008 eng d00aCorrespondence: Another surge of Variegated Glacier, Alaska, USA, 2003/040 aCorrespondence Another surge of Variegated Glacier Alaska USA 20 a192-2000 v541 aHarrison, W1 aMotyka, Roman, J.1 aTruffer, Martin uhttp://www.ingentaconnect.com/content/igsoc/jog/2008/00000054/00000184/art0001900575nas a2200169 4500008004100000245010200041210006900143300001100212490000700223100002300230700002000253700001600273700002100289700001200310700002200322856006100344 2008 eng d00aGlacier, fjord, and seismic response to recent large calving events, Jakobshavn Isbræ, Greenland0 aGlacier fjord and seismic response to recent large calving event aL225010 v351 aAmundson, Jason, M1 aTruffer, Martin1 aLüthi, M P1 aFahnestock, Mark1 aWest, M1 aMotyka, Roman, J. uhttp://www.agu.org/pubs/crossref/2008/2008GL035281.shtml00570nas a2200145 4500008004100000245011500041210006900156300001400225490000700239100001700246700001600263700002200279700002000301856010300321 2008 eng d00aSeasonal fluctuations in the advance of a tidewater glacier and potential causes: Hubbard Glacier, Alaska, USA0 aSeasonal fluctuations in the advance of a tidewater glacier and a401–4110 v541 aRitchie, J B1 aLingle, C S1 aMotyka, Roman, J.1 aTruffer, Martin uhttp://openurl.ingenta.com/content/xref?genre=article&issn=0022-1430&volume=54&issue=186&spage=40100461nas a2200133 4500008004100000245009600041210006900137300001400206490000700220100001500227700002200242700002000264856004300284 2007 eng d00aFlotation and retreat of a lake-calving terminus, Mendenhall Glacier, southeast Alaska, USA0 aFlotation and retreat of a lakecalving terminus Mendenhall Glaci a211–2240 v531 aBoyce, E S1 aMotyka, Roman, J.1 aTruffer, Martin uhttps://glaciers.gi.alaska.edu/node/1500541nas a2200157 4500008004100000245010600041210006900147300001100216490000800227100002200235700002200257700002400279700002000303700001800323856004200341 2007 eng d00aGlacier changes in southeast Alaska and northwest British Columbia and contribution to sea level rise0 aGlacier changes in southeast Alaska and northwest British Columb aF010070 v1121 aLarsen, Chris, F.1 aMotyka, Roman, J.1 aArendt, Anthony, A.1 aEchelmeyer, K A1 aGeissler, P E uhttps://glaciers.gi.alaska.edu/node/700493nas a2200157 4500008004100000245007500041210006900116300001200185490000700197100001600204700002200220700001400242700001600256700002000272856004300292 2007 eng d00aGlaciervolcano interactions in the North Crater of Mt Wrangell, Alaska0 aGlaciervolcano interactions in the North Crater of Mt Wrangell A a48–570 v451 aBenson, C S1 aMotyka, Roman, J.1 aMcNUTT, S1 aLüthi, M P1 aTruffer, Martin uhttps://glaciers.gi.alaska.edu/node/1600449nas a2200121 4500008004100000245011400041210006900155300001100224490000800235100002200243700002000265856004200285 2007 eng d00aHubbard Glacier, Alaska: 2002 closure and outburst of Russell Fjord and postflood conditions at Gilbert Point0 aHubbard Glacier Alaska 2002 closure and outburst of Russell Fjor aF020040 v1121 aMotyka, Roman, J.1 aTruffer, Martin uhttps://glaciers.gi.alaska.edu/node/500500nas a2200145 4500008004100000245009100041210006900132300001200201490000600213100002200219700002200241700002900263700002000292856004200312 2007 eng d00aPost Little Ice Age Glacial Rebound in Glacier Bay National Park and Surrounding Areas0 aPost Little Ice Age Glacial Rebound in Glacier Bay National Park a36–410 v61 aMotyka, Roman, J.1 aLarsen, Chris, F.1 aFreymueller, Jeffrey, T.1 aEchelmeyer, K A uhttps://glaciers.gi.alaska.edu/node/601742nas a2200157 4500008004000000245011900040210006900159300001200228490000600240520117400246100002201420700001601442700002201458700002001480856008401500 0 engd00aHazard assessment of the Tidal Inlet landslide and potential subsequent tsunami, Glacier Bay National Park, Alaska0 aHazard assessment of the Tidal Inlet landslide and potential sub a205-2150 v43 aAn unstable rock slump, estimated at 5 to 10 × 106 m3, lies perched above the northern shore of Tidal Inlet in Glacier Bay National Park, Alaska. This landslide mass has the potential to rapidly move into Tidal Inlet and generate large, long-period-impulse tsunami waves. Field and photographic examination revealed that the landslide moved between 1892 and 1919 after the retreat of the Little Ice Age glaciers from Tidal Inlet in 1890. Global positioning system measurements over a 2-year period show that the perched mass is presently moving at 3–4 cm annually indicating the landslide remains unstable. Numerical simulations of landslide-generated waves suggest that in the western arm of Glacier Bay, wave amplitudes would be greatest near the mouth of Tidal Inlet and slightly decrease with water depth according to Green’s law. As a function of time, wave amplitude would be greatest within approximately 40 min of the landslide entering water, with significant wave activity continuing for potentially several hours.1 aWieczorek, Gerald1 aGeist, Eric1 aMotyka, Roman, J.1 aJakob, Matthias uhttp://www.ingentaconnect.com/content/klu/10346/2007/00000004/00000003/0000008400579nas a2200169 4500008004000000245007600040210006900116300001200185490000700197100002200204700001900226700002000245700001800265700001800283700002400301856008400325 0 engd00aHubbard Glacier update: another closure of Russell Fiord in the making?0 aHubbard Glacier update another closure of Russell Fiord in the m a562-5640 v541 aMotyka, Roman, J.1 aLawson, Daniel1 aFinnegan, David1 aKalli, George1 aMolnia, Bruce1 aArendt, Anthony, A. uhttp://www.ingentaconnect.com/content/igsoc/jog/2008/00000054/00000186/art00020