Ice Volume Estimates from Ground-Penetrating Radar Surveys, Wedel Jarlsberg Land Glaciers, Svalbard

Navarro, Francisco; Martín-Español, Alba; Lapazaran, Javier; Grabiec, Mariusz; Otero, Jaime; Vasilenko, E.V.; Puczko, Dariusz

doi:10.1657/1938-4246-46.2.394

Cited by 41 publications

(68 citation statements)

References 46 publications

(52 reference statements)

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“…Bed topography was derived from ground-penetrating radar (GPR) data (Grabiec et al, 2012;Navarro et al, 2014) and depth soundings in the glacier forebay (Vieli et al, 2002). The resulting initial geometry of the modeled glacier is shown in Figure 2.…”

Section: Glacier Geometrymentioning

confidence: 99%

Modeling the Controls on the Front Position of a Tidewater Glacier in Svalbard

et al. 2017

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Calving is an important mass-loss process at ice sheet and marine-terminating glacier margins, but identifying and quantifying its principal driving mechanisms remains challenging. Hansbreen is a grounded tidewater glacier in southern Spitsbergen, Svalbard, with a rich history of field and remote sensing observations. The available data make this glacier suitable for evaluating mechanisms and controls on calving, some of which are considered in this paper. We use a full-Stokes thermomechanical 2D flow model (Elmer/Ice), paired with a crevasse-depth calving criterion, to estimate Hansbreen's front position at a weekly time resolution. The basal sliding coefficient is re-calibrated every 4 weeks by solving an inverse model. We investigate the possible role of backpressure at the front (a function of ice mélange concentration) and the depth of water filling crevasses by examining the model's ability to reproduce the observed seasonal cycles of terminus advance and retreat. Our results suggest that the ice-mélange pressure plays an important role in the seasonal advance and retreat of the ice front, and that the crevasse-depth calving criterion, when driven by modeled surface meltwater, closely replicates observed variations in terminus position. These results suggest that tidewater glacier behavior is influenced by both oceanic and atmospheric processes, and that neither of them should be ignored.

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Section: Glacier Geometrymentioning

confidence: 99%

Modeling the Controls on the Front Position of a Tidewater Glacier in Svalbard

et al. 2017

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“…Between 2004 and 2013, GPR profiles were collected both on THPB and WSB (Navarro et al, 2014). These surveys provide a dense grid over most parts of these glaciers (Fig.…”

Section: Thickness Measurementsmentioning

confidence: 99%

“…Thickness values for marine ice fronts are non-zero and a natural outcome of the underlying mass budget calculation. For VIC, thickness measurements (coloured dots) were collected with airborne radio-echo sounding instruments (Dowdeswell et al, 1986) as well as with ground-based pulsed radar systems Navarro et al, 2014). For THPB and WSB, measurements were collected during several GPR campaigns between 2004 and 2012 (Navarro et al, 2014).…”

Section: Ice Fluxmentioning

confidence: 99%

Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard

et al. 2017

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Abstract. The basal topography is largely unknown beneath most glaciers and ice caps, and many attempts have been made to estimate a thickness field from other more accessible information at the surface. Here, we present a two-step reconstruction approach for ice thickness that solves mass conservation over single or several connected drainage basins. The approach is applied to a variety of test geometries with abundant thickness measurements including marine-and landterminating glaciers as well as a 2400 km 2 ice cap on Svalbard. The input requirements are kept to a minimum for the first step. In this step, a geometrically controlled, non-local flux solution is converted into thickness values relying on the shallow ice approximation (SIA). In a second step, the thickness field is updated along fast-flowing glacier trunks on the basis of velocity observations. Both steps account for available thickness measurements. Each thickness field is presented together with an error-estimate map based on a formal propagation of input uncertainties. These error estimates point out that the thickness field is least constrained near ice divides or in other stagnant areas. Withholding a share of the thickness measurements, error estimates tend to overestimate mismatch values in a median sense. We also have to accept an aggregate uncertainty of at least 25 % in the reconstructed thickness field for glaciers with very sparse or no observations. For Vestfonna ice cap (VIC), a previous ice volume estimate based on the same measurement record as used here has to be corrected upward by 22 %. We also find that a 13 % area fraction of the ice cap is in fact grounded below sea level. The former 5 % estimate from a direct measurement interpolation exceeds an aggregate maximum range of 6-23 % as inferred from the error estimates here.

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“…It is considered as a quite small Svalbard glacier of 6.5 km long, 2.2 km wide, with a surface of 27.1 km 2 located between 40 and 650 m a.s.l (Ignatiuk et al, 2014;Majchrowska et al, 2015). It has a maximum thickness of about 275 m and a cold ice snout less than 50 m 25 thick frozen to the bedrock up to 700 m upstream from the front line (Navarro et al, 2014;Pälli et al, 2003). Its entire surface composed by cold ice (below the pressure melting point) overlying on a temperate ice layer (at the pressure melting point) ( Fig.1(a)) (Grabiec et al, 2017), allows the presence of a well-developed supraglacial drainage system.…”

Section: Study Areamentioning

confidence: 99%

“…In the accumulation area temperate ice and firn are present, allowing water percolation through the glacier body while the structure of the ablation area is similar to Werenskioldbreen with a cold ice layer overlying temperate ice ( Fig.1(b)) (Grabiec et al, 2017;Navarro et al, 2014), preventing a disperse infiltration of the 5 water directly inside the glacier. Those two glaciers are characterized by the most common Svalbard polythermal structure which implies that the majority of the bare ice surface is composed by cold ice (Fig.2) (Grabiec et al, 2017;Navarro et al, 2014;Pälli et al, 2003). Thus the superficial part is composed by an impermeable layer which results to the development of a well channelized dendritic supraglacial drainage system (Irvine-Fynn et al, 2011).…”

Section: Study Areamentioning

confidence: 99%

Role of discrete recharge from the supraglacial drainage system for modelling of subglacial conduits pattern of Svalbard polythermal glaciers

Decaux

Grabiec

Ignatiuk

et al. 2018

Preprint

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Abstract. Being a determinant factor of the glacier's dynamic, subglacial water behavior needs a special attention. Water flowing from the glacier's surface is the principal source supplying the subglacial drainage system. Therefore, insight into the state and evolution of the supraglacial drainage system is crucial for recognition of recharge pattern of the englacial and subglacial drainage pathways. Climate warming causes increased ablation generating higher amount of meltwater and thinning of glacier.Decadal timescale evolution of the supraglacial drainage leads to some modifications of the system in opposition to its nearly 5 stable state on an annual timescale. For two studied glaciers Hansbreen and Werenskioldbreen in southern Svalbard surface meltwater is the main runoff component. During the ablation season 2015, 72.5 % of the total amount was provided by meltwater and 27.5 % by precipitations. Supraglacial catchments were determined on the high resolution digital elevation model using standard watershed modelling tool in ArcGIS, for each water-input area (WIA). Spatialized water runoff calculations for all the main WIAs have been done. Having data on the water sources from catchments delimited on glacier's surface, mod-10 elling of a theoretical pattern of subglacial conduits was done considering discrete water recharge via moulins, shear fractures or crevasses. Classical modelling with an assumption of homogeneous water supply was done for comparison. Several water pressure conditions have been taken into account as well. Results show that models of subglacial drainage system with homogeneous water recharge are more realistic for tidewater glaciers with rather broad permeable firn areas and creased frontal zones, while discrete water recharge models are better for land-terminating glaciers with almost continuous impermeable su-15 perficial cold ice layer. Subglacial channel models are assumed to be valid for a minimum period of two decades taking into account evolution of supraglacial drainage system and ice thickness changes of Svalbard polythermal glaciers.

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Ice Volume Estimates from Ground-Penetrating Radar Surveys, Wedel Jarlsberg Land Glaciers, Svalbard

Cited by 41 publications

References 46 publications

Modeling the Controls on the Front Position of a Tidewater Glacier in Svalbard

Modeling the Controls on the Front Position of a Tidewater Glacier in Svalbard

Application of a two-step approach for mapping ice thickness to various glacier types on Svalbard

Role of discrete recharge from the supraglacial drainage system for modelling of subglacial conduits pattern of Svalbard polythermal glaciers

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