Abstract. This study presents the application of a cost-effective, unmanned aerial vehicle (UAV) to investigate calving dynamics at major marine-terminating outlet glacier draining western sector Greenland ice sheet. The UAV was flown over Store Glacier on three sorties during summer 2013 and acquired 2000 overlapping, geotagged images front an ~40 cm ground sampling distance. Stereo-photogrammetry applied these enabled extraction high-resolution digital elevation models (DEMs) with vertical...

Abstract. While it has been shown repeatedly that ocean conditions exhibit an important control on the behaviour of grounded tidewater glaciers, modelling studies have focused largely effects basal and surface melting. Here, a finite-element model stresses near front glacier is used to investigate frontal melting calving, independently calving criterion used. Applications stress idealized scenarios reveal undercutting ice due can drive at up ten times mean melt rate. Factors which cause...

[1] We have developed an automatic method to identify changes in the position of calving glacier margins using daily MODIS imagery. Application 32 ocean-terminating glaciers East Greenland produced 26,802 margin positions for a 10 year long period (2000–2009). report these high-resolution data and show that exhibit seasonal cycles with magnitudes advance retreat proportional width. Despite similar seasonality there is distinct difference between interannual trends front north south 69°N. All...

Abstract. We use a full-Stokes 2-D model (Elmer/Ice) to investigate the flow and calving dynamics of Store Glacier, fast-flowing outlet glacier in West Greenland. Based on new, subgrid-scale implementation crevasse depth criterion, we perform two sets simulations: one identify primary forcing mechanisms another constrain future stability. find that mixture icebergs sea ice, known as ice mélange or sikussak, is principally responsible for observed seasonal advance front. On other hand, effect...

Abstract. Warm, subtropical-originating Atlantic water (AW) has been identified as a primary driver of mass loss across the marine sectors Greenland Ice Sheet (GrIS), yet specific processes by which this interacts with and erodes calving front tidewater glaciers is frequently modelled much speculated upon but remains largely unobserved. We present suite fjord salinity, temperature, turbidity versus depth casts along glacial runoff estimation from Rink Store glaciers, two major outlets...

Marine‐terminating outlet glaciers of the Greenland Ice Sheet make significant contributions to global sea level rise, yet conditions that facilitate their fast flow remain poorly constrained owing a paucity data. We drilled and instrumented seven boreholes on Store Glacier, Greenland, monitor subglacial water pressure, temperature, electrical conductivity, turbidity along with englacial ice temperature deformation. These observations were supplemented by surface velocity meteorological...

Abstract Iceberg calving accounts for around half of all mass loss from both the Greenland and Antarctic ice sheets. The diverse nature its complex links to internal dynamics climate make it challenging incorporate into models glaciers Here we present results a new open‐source 3‐D full‐Stokes model developed in Elmer/Ice. implements crevasse depth criterion, which states that occurs when surface basal crevasses penetrate full thickness glacier. also rediscretization approach time‐evolution...

Abstract. Unmanned aerial vehicles (UAVs) and structure from motion with multi-view stereo (SfM–MVS) photogrammetry are increasingly common tools for geoscience applications, but final product accuracy can be significantly diminished in the absence of a dense well-distributed network ground control points (GCPs). This is problematic inaccessible or hazardous field environments, including highly crevassed glaciers, where implementing suitable GCP networks would logistically difficult if not...

Abstract Discharge from marine-terminating outlet glaciers accounts for up to half the recent mass loss Greenland ice sheet, yet causal factors are not fully understood. Here we assess controlling behaviour of Humboldt Glacier (HG), allowing us evaluate influence basal topography on glacier response external forcing since part HG’s terminus occupies a large overdeepening. retreat accelerated dramatically after 1999, coinciding with summer atmospheric warming 0.19°C –1 and sea-ice decline....

Predicting the retreat of tidewater outlet glaciers forms a major obstacle to forecasting rate mass loss from Greenland Ice Sheet. This reflects challenges modeling highly dynamic, topographically complex, and data-poor environment glacier-fjord systems that link ice sheet ocean. To avoid these difficulties, we investigate extent which glacier can be explained by simple variables: air temperature, meltwater runoff, ocean two parameterizations "ocean/atmosphere" forcing based on combined...

Abstract Distributed Acoustic Sensing (DAS) is a new technology in which seismic energy detected, at high spatial and temporal resolution, using the propagation of laser pulses fiber‐optic cable. We show analyses from first glaciological borehole DAS deployment to measure englacial subglacial properties Store Glacier, fast‐flowing outlet Greenland Ice Sheet. record compressional shear waves 1,043 m‐deep vertical profiles, sampled 10 m detect transition isotropic anisotropic ice 84%...

Supraglacial lake drainage events influence Greenland Ice Sheet dynamics on hourly to interannual timescales. However, direct observations are rare, and, date, no in situ studies exist from fast-flowing sectors of the ice sheet. Here, we present a rapid event at Store Glacier, west Greenland, 2018. The transported 4.8 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>×</mml:mo> </mml:math> 10 6 m 3 meltwater glacier bed <mml:mo>∼</mml:mo> 5 h, reducing third...

Uncertainty associated with ice sheet motion plagues sea level rise predictions. Much of this uncertainty arises from imperfect representations physical processes including basal slip and internal deformation, models largely incapable reproducing borehole-based observations. Here, we model isolated three-dimensional domains fast-moving (Sermeq Kujalleq/Store Glacier) slow-moving (Isunnguata Sermia) settings in Greenland. By incorporating realistic geostatistically simulated topography, show...

Abstract. Hydrographic data acquired in Kangerdlugssuaq Fjord and adjacent seas 1993 2004 are used together with reanalysis from the NEMO ocean modelling framework to elucidate water-mass change ice-ocean-atmosphere interactions East Greenland. The hydrographic show that fjord contains warm subtropical waters were considerably warmer than 1993. shows properties of related a major peak oceanic shoreward heat flux into cross-shelf trough on outer continental shelf. this varies according...

Satellite observations have revealed active hydrologic systems beneath Antarctic ice streams, but sources and sinks of water within these are uncertain. Here we use numerical simulations streams to estimate the generation, flux, budget five on Siple Coast. We that 47% total input (0.98 km3 yr−1) Whillans (WIS), Mercer (MIS), Kamb (KIS) comes from sheet interior only 8% forms by local basal melting. The remaining 45% a groundwater reservoir, an overlooked source in which depletion...

Abstract Subglacial lakes are an established and important component of the basal hydrological system Antarctic ice sheets, but none have been reported from Greenland. Here we present airborne radio echo sounder (RES) measurements that provide first clear evidence for existence subglacial in Two lakes, with areas ~8 ~10 km 2 , found northwest sector sheet, ~40 margin, below 757 809 m ice, respectively. The setting Greenland differs those being beneath relatively thin cold pointing to a...

[1] Predicting ice sheet mass balance is challenging because of the complex flow streams. To address this issue, we have coupled a three-dimensional higher-order model to basal processes where subglacial till has plastic rheology and evolving yield stress. The was tested for its sensitivity regional water availability. First, with an assumed undrained bed, stream oscillates between active stagnant phases, solely as result thermodynamic feedbacks occurring at ice-till interface. However,...

Supraglacial lakes on the Greenland Ice Sheet are expanding inland, but impact ice flow is equivocal because interior surface conditions may preclude transfer of water to bed. Here we use a well-constrained 3D model demonstrate that supraglacial in drain when tensile-stress perturbations propagate fractures areas where normally absent or closed. These melt-induced escalate as far 80 km apart form expansive networks and rapid succession. The result tensile shock establishes new surface-to-bed...

Abstract We present the first fully coupled 3D full-Stokes model of a tidewater glacier, incorporating ice flow, subglacial hydrology, plume-induced frontal melting and calving. apply to Store Glacier ( Sermeq Kujalleq ) in west Greenland simulate year high melt (2012) one low (2017). In terms modelled we find perennial channels extending 5 km inland from terminus up 41 29 summer 2012 2017, respectively. also report hydrodynamic feedback that suppresses channel growth under thicker allows...

We have constructed a high‐resolution numerical model of heat, water, and solute flows in sub‐ice stream till subjected to basal freeze‐on. The builds on quantitative treatments frost heave permafrost soils. full version the Clapeyron equation is used. Hence, ice‐water phase transition depends water pressure, osmotic surface tension. two latter effects can lead supercooling ice base. This supercooling, turn, induces hydraulic gradients that drive upward flow pore which feeds growth...

The brightness distribution of sequentially extracted borehole camera imagery shows two distinct sequences basal ice in Kamb Ice Stream. upper sequence (7.3 m) comprises clear and layers with dispersed stratified debris. lower (8.2 consists accretion alternating solid have volumetric debris contents about 5% 20%, respectively. We infer that the formed a tributary where subglacial meltwater was abundant on Siple Coast plain freezing currently dominates thermal regime. layer contains...

Abstract The Whillans Ice Stream Plain (WIP) has been slowing since at least 1963. Prior constraints on this slowdown were consistent with a constant long‐term deceleration rate. New observations of ice velocity from 11 continuous and 3 seasonal GPS sites indicate the rate varies through time including interannual scales. Between 2009 2012 WIP decelerated (6.1 to 10.9 ± 2 m/yr ) that was double multidecadal average (3.0 5.6 ). To identify causes slowdown, we used new prior estimates...