scholarly journals Drainage system and thermal structure of a High Arctic polythermal glacier: Waldemarbreen, western Svalbard

2021 ◽  
pp. 1-14
Author(s):  
Jānis Karušs ◽  
Kristaps Lamsters ◽  
Ireneusz Sobota ◽  
Jurijs Ješkins ◽  
Pēteris Džeriņš ◽  
...  
Keyword(s):  
Thermal Structure ◽  
Drainage System ◽  
Radar Data ◽  
High Arctic ◽  
Ice Age ◽  
Water Drainage ◽  
Near Surface ◽  
Thermal Change ◽  
Polythermal Glacier ◽  
Surface Ice

Abstract Understanding glacier drainage system behaviour and its response to increased meltwater production faces several challenges in the High Arctic because many glaciers are transitioning from polythermal to almost entirely cold thermal structures. We, therefore, used ground-penetrating radar data to investigate the thermal structure and drainage system of Waldemarbreen in Svalbard: a small High Arctic glacier believed to be undergoing thermal change. We found that Waldemarbreen retains up to 80 m of temperate ice in its upper reaches, but this thickness most likely is a relict from the Little Ice Age when greater ice volumes were insulated from winter cooling and caused greater driving stresses. Since then, negative mass balance and firn loss have prevented latent heat release and allowed near-surface ice temperatures to cool in winter, thus reducing the thickness of the temperate ice. Numerous reflectors that can be traced up-glacier are interpreted as englacial channels formed by hydrofracturing in the crevassed upper region of the glacier. The alternative cut and closure mechanism of conduit initiation only forms conduits in parts of the lower ablation area. Consequently, Waldemarbreen provides evidence that hydrofracturing at higher elevations can play a major role in englacial water drainage through cold ice.

scholarly journals Thermal structure and drainage system of a small valley glacier (Tellbreen, Svalbard), investigated by Ground Penetrating Radar

2010 ◽  
Vol 4 (4) ◽  
pp. 2169-2199
Author(s):  
K. Bælum ◽  
D. I. Benn
Keyword(s):  
Ground Penetrating Radar ◽  
Thermal Structure ◽  
Drainage System ◽  
High Arctic ◽  
Differential Gps ◽  
Glacier Surface ◽  
Drainage Channels ◽  
Polythermal Glacier ◽  
Ground Penetrating ◽  
Subglacial Drainage

Abstract. Proglacial icings accumulate in front of many High Arctic glaciers during the winter months, as water escapes from englacial or subglacial storage. Such icings have been interpreted as evidence for warm-based subglacial conditions, but several are now known to occur in front of cold-based glaciers. In this study, we investigate the drainage system of Tellbreen, a 3.5 km long cold-based polythermal glacier in central Spitsbergen, where a large proglacial icing develops each winter, to determine the location and geometry of storage elements. DEMs of the glacier surface and bed were constructed using maps, differential GPS and GPR. Patterns of surface lowering indicate that the glacier has a long-term mass balance of −0.6 ± 0.2 m/year. Englacial and subglacial drainage channels were mapped using Ground penetrating radar (GPR), showing that Tellbreen has a diverse drainage system that is capable of storing, transporting and releasing water year round. In the upper part of the glacier, drainage is mainly via supraglacial channels. These transition downglacier into shallow englacial "cut and closure" channels, formed by the incision and closure of supraglacial channels. Below thin ice near the terminus, these channels reach the bed and contain stored water throughout the winter months. Even though the bed is below pressure-melting point, Tellbreen has a surface-fed, channelized subglacial drainage system, which allows significant storage and delayed discharge.

scholarly journals Cryoconite hole connectivity on the Wright Lower Glacier, McMurdo Dry Valleys, Antarctica

2016 ◽  
Vol 62 (234) ◽  
pp. 714-724 ◽  
Author(s):  
SHELLEY MACDONELL ◽  
MARTIN SHARP ◽  
SEAN FITZSIMONS
Keyword(s):  
Spatial Variability ◽  
Drainage System ◽  
Chloride Content ◽  
Mcmurdo Dry Valleys ◽  
Hydrological Connectivity ◽  
Dry Valleys ◽  
Near Surface ◽  
Cryoconite Hole ◽  
Transfer Method ◽  
Surface Ice

ABSTRACTCryoconite holes can be important sources and stores of water and nutrients on cold and polythermal glaciers, and they provide a habitat for various forms of biota. Understanding the hydrological connectivity of cryoconite holes may be the key to understanding the transport of nutrients and biological material to the proglacial areas of such glaciers. This paper aims to characterize and explain spatial variability in the connectivity of ice-lidded cryoconite holes on a small, piedmont glacier in the McMurdo Dry Valleys through geochemical analysis of cryoconite hole waters. Solute concentrations in both surface and near-surface ice and cryoconite holes, vary greatly along the glacier centerline, and all sample types displayed similar spatial patterns of variability. Using chloride as a tracer, we estimated variations in cryoconite hole connectivity along the glacier centerline. We found that a previously used mass transfer method did not provide reliable estimates of the time period for which cryoconite hole waters had been isolated from the atmosphere. We attribute this to spatial variability in both the chloride content of the surface ice and surface ablation rates. The approach may, however, be used to qualitatively characterize spatial variations in the hydrological connectivity of the cryoconite holes. These results also suggest that ice-lidded cryoconite holes are never truly isolated from the near-surface drainage system.

scholarly journals Thermal structure and drainage system of a small valley glacier (Tellbreen, Svalbard), investigated by ground penetrating radar

2011 ◽  
Vol 5 (1) ◽  
pp. 139-149 ◽  
Author(s):  
K. Bælum ◽  
D. I. Benn
Keyword(s):  
Ground Penetrating Radar ◽  
Thermal Structure ◽  
Drainage System ◽  
High Arctic ◽  
Differential Gps ◽  
Glacier Surface ◽  
Digital Elevation ◽  
Drainage Channels ◽  
Ground Penetrating ◽  
Subglacial Drainage

Abstract. Proglacial icings accumulate in front of many High Arctic glaciers during the winter months, as water escapes from englacial or subglacial storage. Such icings have been interpreted as evidence for warm-based subglacial conditions, but several are now known to occur in front of cold-based glaciers. In this study, we investigate the drainage system of Tellbreen, a 3.5 km long glacier in central Spitsbergen, where a large proglacial icing develops each winter, to determine the location and geometry of storage elements. Digital elevation models (DEMs) of the glacier surface and bed were constructed using maps, differential GPS and ground penetrating radar (GPR). Rates of surface lowering indicate that the glacier has a long-term mass balance of −0.6 ± 0.2 m/year. Englacial and subglacial drainage channels were mapped using GPR, showing that Tellbreen has a diverse drainage system that is capable of storing, transporting and releasing water year round. In the upper part of the glacier, drainage is mainly via supraglacial channels. These transition downglacier into shallow englacial "cut and closure" channels, formed by the incision and roof closure of supraglacial channels. Below thin ice near the terminus, these channels reach the bed and contain stored water throughout the winter months. Even though no signs of temperate ice were detected and the bed is below pressure-melting point, Tellbreen has a surface-fed, channelized subglacial drainage system, which allows significant storage and delayed discharge.

scholarly journals Englacial drainage structures in an East Antarctic outlet glacier

2019 ◽  
Vol 66 (255) ◽  
pp. 166-174 ◽  
Author(s):  
Thomas Schaap ◽  
Michael J. Roach ◽  
Leo E. Peters ◽  
Sue Cook ◽  
Bernd Kulessa ◽  
...  
Keyword(s):  
Drainage System ◽  
Austral Summer ◽  
Greenland Ice Sheet ◽  
Radar Data ◽  
The Arctic ◽  
Outlet Glacier ◽  
Near Surface ◽  
Surface Mass ◽  
Hydrological System ◽  
Englacial Drainage

AbstractGround-penetrating radar data acquired in the 2016/17 austral summer on Sørsdal Glacier, East Antarctica, provide evidence for meltwater lenses within porous surface ice that are conceptually similar to firn aquifers observed on the Greenland Ice Sheet and the Arctic and Alpine glaciers. These englacial water bodies are associated with a dry relict surface basin and consistent with perennial drainage into an interconnected englacial drainage system, which may explain a large englacial outburst flood observed in satellite imagery in the early 2016/17 melt season. Our observations indicate the rarely-documented presence of an englacial hydrological system in Antarctica, with implications for the storage and routing of surface meltwater. Future work should ascertain the spatial prevalence of such systems around the Antarctic coastline, and identify the degree of surface runoff redistribution and storage in the near surface, to quantify their impact on surface mass balance.

scholarly journals A cross-validated three-dimensional model of an englacial and subglacial drainage system in a High-Arctic glacier

2020 ◽  
Vol 66 (256) ◽  
pp. 278-290
Author(s):  
Lena U. Hansen ◽  
Jan A. Piotrowski ◽  
Douglas I. Benn ◽  
Heidi Sevestre
Keyword(s):  
Three Dimensional ◽  
Drainage System ◽  
High Arctic ◽  
Water Drainage ◽  
Three Dimensional Model ◽  
Closure Mechanism ◽  
Ground Penetrating ◽  
Arctic Glacier ◽  
D Model ◽  
Englacial Drainage

AbstractRecent speleological surveys of meltwater drainage systems in cold and polythermal glaciers have documented dynamic englacial and in some cases subglacial conduits formed by the ‘cut-and-closure’ mechanism. Investigations of the spatial distribution of such conduits often require a combination of different methods. Here, we studied the englacial drainage system in the cold glacier Longyearbreen, Svalbard by combining speleological exploration of a 478 m long meltwater conduit with a high-resolution ground penetrating radar (GPR) survey with two different centre-frequencies (25 and 100 MHz). The results yielded a 3-D documentation of the present englacial drainage system. The study shows that the overall form of englacial conduits can be detected from velocity−depth converted GPR data, and that the 3-D model can facilitate a method to pinpoint the reflections in a radargram corresponding with the englacial drainage system, although fine detail cannot be resolved. Visible reflections approximately parallel to the mapped englacial water drainage system likely result from sediment incorporated in the ice or from abandoned parts of the englacial drainage system.

scholarly journals Mapping thermal and hydrological conditions beneath a polythermal glacier with radio-echo sounding

2001 ◽  
Vol 47 (157) ◽  
pp. 232-242 ◽  
Author(s):  
Luke Copland ◽  
Martin Sharp
Keyword(s):  
Thermal Structure ◽  
Basal Layer ◽  
Equipotential Surface ◽  
High Arctic ◽  
Hydrological Conditions ◽  
Glacier Terminus ◽  
Radio Echo Sounding ◽  
Pressure Melting ◽  
Polythermal Glacier ◽  
Echo Sounding

AbstractSpatial patterns in residual bed reflection power (BRPr), derived from ground-based radio-echo sounding, were mapped and interpreted in terms of the thermal and hydrological conditions at the base of a high-Arctic polythermal glacier (John Evans Glacier, Ellesmere Island, Canada). BRPr is the residual from a statistical relationship between measured bed reflection power and ice thickness that describes the rate of dielectric loss with depth in the glacier. We identified three types of thermal structure: (a) Positive BRPr and an internal reflecting horizon occur over the glacier terminus. The reflecting horizon is interpreted as the boundary between warm and cold ice, and suggests the presence of a warm basal layer. (b) Positive BRPr occurs without an internal reflector in the upper part of the ablation zone. This suggests that ice is at the pressure-melting point only at the bed. (c) Negative BRPr without an internal reflector occurs in all other regions, suggesting cold ice at the bed. Where BRPr is positive, its pattern is similar to the pattern of subglacial water flow predicted from the form of the subglacial hydraulic equipotential surface. This suggests that hydrological conditions at the glacier bed are a major control on BRPr, probably because the dielectric contrast between ice and water is higher than that between ice and other subglacial materials.

scholarly journals Glacier thermal regime and suspended-sediment yield: a comparison of two high-Arctic glaciers

1997 ◽  
Vol 24 ◽  
pp. 32-37 ◽  
Author(s):  
A. J. Hodson ◽  
M. Tranter ◽  
J. A. Dowdeswell ◽  
A. M. Gurnell ◽  
J. O. Hagen
Keyword(s):  
Suspended Sediment ◽  
Thermal Regime ◽  
Sediment Yield ◽  
Drainage System ◽  
Sediment Concentration ◽  
High Arctic ◽  
Ice Age ◽  
Sediment Yields ◽  
Suspended Sediment Yield ◽  
Order Of Magnitude

This paper compares estimates of suspended-sediment yield and discharge from two glacier basins in Svalhard exhibiting contrasting glacial thermal regimes: Austre Brøggerbreen (~12 km2), which is almost entirely cold-based, and Finsterwalderbreen (~44 km2), dominated by warm basal ice. There are marked differences in the magnitude and temporal pattern of mean daily discharge and mean daily suspended-sediment concentration from the two glacier basins. Specific suspended-sediment yields from Finsterwalderbreen (710–2900 t km−2 a−1) were more than one order of magnitude greater than at Austre Brøggerbreen (81–110 t km−2 a−1). These differences are ascribed to the influence of thermal regime upon the meltwater drainage system and the predominant sources of suspended sediment. The potential significance of glacier thermal regime is further explored using studies from other glacier basins in Svalbard. Variations in thermal regime resulting from mass-balance adjustments since the termination of the Little Ice Age are also examined.

scholarly journals Organochlorine Pollutants within a Polythermal Glacier in the Interior Eastern Alaska Range

2018 ◽  
Author(s):  
Kimberley R. Miner ◽  
Seth Campbell ◽  
Christopher Gerbi ◽  
Anna Lilijedahl ◽  
Therese Anderson ◽  
...  
Keyword(s):  
Atmospheric Transport ◽  
Ice Core ◽  
Alaska Range ◽  
Near Surface ◽  
Glacial Meltwater ◽  
Organochlorine Pollutants ◽  
Core Samples ◽  
Interior Alaska ◽  
Polythermal Glacier ◽  
Surface Ice

To assess the presence of organochlorine pollutants (OCP) in Alaskan sub-Arctic latitudes, we analyzed ice core and meltwater samples from Jarvis Glacier, a polythermal glacier in Interior Alaska. Jarvis Glacier is receding as atmospheric warming continues throughout the region, increasing opportunity for OCP transport both englacially and into the proglacial watershed. Across all meltwater and ice core samples we identify the pesticides DDT, DDE and DDD, α- HCH and ϒ-HCH. OCP concentrations in ice core samples were highest at the 7-14 m depth (0.51 ng/L of DDT) and decreased gradually approaching the bedrock at 79m. Meltwater concentrations from the proglacial creek slightly exceeded concentrations found in the ice core, potentially indicating aggregate OCP glacial loss, with peak OCP concentration (1.12 ng/L of DDD) taken in July and potentially associated to peak melt. Ongoing use of DDT to fight Malaria in Asia, and the extended atmospheric range of HCH may account for concentrations in near-surface ice, correlating with use and atmospheric transport. The opportunity for biota bioaccumulation of OCPs, or human uptake of OCPs from glacial meltwater, may increase as glacial melt continues.

scholarly journals Processes influencing heat transfer in the near-surface ice of Greenland's ablation zone

2018 ◽  
Vol 12 (10) ◽  
pp. 3215-3227 ◽  
Author(s):  
Benjamin H. Hills ◽  
Joel T. Harper ◽  
Toby W. Meierbachtol ◽  
Jesse V. Johnson ◽  
Neil F. Humphrey ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Air Temperature ◽  
Thermal Structure ◽  
Radiative Energy ◽  
Ablation Zone ◽  
Transient Heating ◽  
Near Surface ◽  
The Mean ◽  
Surface Ice ◽  
Mean Annual Air Temperature

Abstract. To assess the influence of various heat transfer processes on the thermal structure of near-surface ice in Greenland's ablation zone, we compare in situ measurements with thermal modeling experiments. A total of seven temperature strings were installed at three different field sites, each with between 17 and 32 sensors and extending up to 21 m below the ice surface. In one string, temperatures were measured every 30 min, and the record is continuous for more than 3 years. We use these measured ice temperatures to constrain our modeling experiments, focusing on four isolated processes and assessing the relative importance of each for the near-surface ice temperature: (1) the moving boundary of an ablating surface, (2) thermal insulation by snow, (3) radiative energy input, and (4) subsurface ice temperature gradients below the seasonally active near-surface layer. In addition to these four processes, transient heating events were observed in two of the temperature strings. Despite no observations of meltwater pathways to the subsurface, these heating events are likely the refreezing of liquid water below 5–10 m of cold ice. Together with subsurface refreezing, the five heat transfer mechanisms presented here account for measured differences of up to 3 ∘C between the mean annual air temperature and the ice temperature at the depth where annual temperature variability is dissipated. Thus, in Greenland's ablation zone, the mean annual air temperature is not a reliable predictor of the near-surface ice temperature, as is commonly assumed.

scholarly journals Distinct Bacterial Communities Exist beneath a High Arctic Polythermal Glacier

2006 ◽  
Vol 72 (9) ◽  
pp. 5838-5845 ◽  
Author(s):  
Maya Bhatia ◽  
Martin Sharp ◽  
Julia Foght
Keyword(s):  
Bacterial Communities ◽  
Drainage System ◽  
High Arctic ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Polymorphism Analysis ◽  
Basal Ice ◽  
Seasonal Flow ◽  
Glacial Environments ◽  
Polythermal Glacier

ABSTRACT Bacterial communities reside in basal ice, sediment, and meltwater in the supra-, sub-, and proglacial environments of John Evans Glacier, Nunavut, Canada. We examined whether the subglacial bacterial community shares common members with the pro- and supraglacial communities, and by inference, whether it could be derived from communities in either of these environments (e.g., by ice overriding proglacial sediments or by in-wash of surface meltwaters). Terminal restriction fragment length polymorphism analysis of bacterial 16S rRNA genes amplified from these environments revealed that the subglacial water, basal ice, and sediment communities were distinct from those detected in supraglacial meltwater and proglacial sediments, with 60 of 142 unique terminal restriction fragments (T-RFs) detected exclusively in subglacial samples and only 8 T-RFs detected in all three environments. Supraglacial waters shared some T-RFs with subglacial water and ice, likely reflecting the seasonal flow of surface meltwater into the subglacial drainage system, whereas supraglacial and proglacial communities shared the fewest T-RFs. Thus, the subglacial community at John Evans Glacier appears to be predominantly autochthonous rather than allochthonous, and it may be adapted to subglacial conditions. Chemical analysis of water and melted ice also revealed differences between the supraglacial and proglacial environments, particularly regarding electrical conductivity and nitrate, sulfate, and dissolved organic carbon concentrations. Whereas the potential exists for common bacterial types to be broadly distributed throughout the glacial system, we have observed distinct bacterial communities in physically and chemically different glacial environments.

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