Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 37 for “"supraglacial"”.
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Supraglacial lake evolution on the Greenland Ice Sheet
Abstract. Supraglacial lakes form annually on the surface of the Greenland Ice Sheet around Paakitsoq, north of the Jakobshavn Isbrae outlet glacier. The lakes are ephemeral, drain through moulins or crevasses at their bed throughout the melt season, and deliver large volumes of water to the …
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Quantifying supraglacial debris thickness at local to regional scales
Supraglacial debris thickness is a key control on the surface energy balance of debris-covered glaciers, which are common in temperate mountain ranges around the world. As such, it is an important input variable to the sorts of models that are used to understand and predict glacier change, which …
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The role of cold supraglacial volcanic deposits in influencing glacial ablation
… factor in glacial ablation is the influence of supraglacial debris deposits, which can have both positive and negative effects. A critical thickness exists at which sub-debris ablation is equal to that of bare ice; debris will hinder ablation if it exceeds this thickness, and enhance it if its …
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Remote sensing of rapidly draining supraglacial lakes on the Greenland Ice Sheet
Supraglacial lakes in the ablation zone of the Greenland Ice Sheet (GrIS) often drain rapidly (in hours to days) by hydraulically-driven fracture (“hydrofracture”) in the summer. Hydrofracture can deliver large meltwater volumes to the ice-bed interface and open-up surface-to-bed connections, …
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Observing the Seasonal Evolution of Supraglacial Ponds in High Mountain Asia: A Supervised Classification Approach
Supraglacial ponds on debris covered glaciers in High Mountain Asia (HMA) can locally store surface runoff and prolong water delivery to downstream river basins (Benn et al., 2012; Miles et al., 2019). Temporal variation in the extent of supraglacial ponding therefore affects the timing and …
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Quantifying Supraglacial Debris Thickness and the Glaciological Controls on its Spatial Distribution in High Mountain Asia
… the current and future spatial distribution of supraglacial debris thickness. This knowledge is indispensible because the mass balance response of DCGs is dependent on the distribution of its debris thickness, given that debris cover can either enhance or inhibit ablation depending on its …
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Inferring subglacial hydrology from investigations of supraglacial lake drainages and meltwater plumes at Store Glacier, West Greenland
… drainage systems come from drainage of supraglacial lakes, crevasses and moulins. The water travel downstream through subglacial channels, eventually reaching the terminus of the glacier, where the freshwater discharge form buoyant plumes that rise through the ambient ocean water, and …
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Quantification of the Impact of Supraglacial Lakes and Slush on Surface Energy Balance of Ice Shelves: Nivlisen Ice Shelf, East Antarctica
Supraglacial lakes (SGLs) and slush are prevalent features of Antarctic ice shelf surface hydrology and efficiently transfer energy to the ice by melt-albedo feedbacks (Dell et al., 2020; Moussavi et al., 2020). There have been few efforts to quantify the energy exchanges between supraglacial …
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Analysis of the surface hydrology of the Greenland Ice Sheet using Sentinel-1 Synthetic Aperture Radar
… to form features such as firn slush zones and supraglacial lakes. This study uses imagery from the recently launched Sentinel-1 Synthetic Aperture Radar sensors to investigate supraglacial lakes in southwest Greenland. This novel method can overcome some of the limitations of optical sensors …
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Laboratory experiments on alluvial cover in mixed bedrock-alluvial meandering channels and on the formation and evolution of supraglacial meltwater meandering streams
Rivers and other channels containing liquid flow develop meandering patterns over different media and across a broad range of scales. For example, alluvial rivers form and evolve by erosion and deposition of sediment, and by interactions with riparian vegetation. Meandering channels also form in …
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The hydrology of debris-covered glaciers
… of Miage Glacier, Western Italian Alps. The supraglacial hydrology was studied by modelling ablation using a distributed energy balance melt model, and measuring supraglacial stream discharges; the structure and evolution of the englacial and subglacial network was investigated using dye …
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The development and application of IceLake, an accurate and computationally efficient model of supraglacial lake evolution in the ablation zone of the Greenland Ice Sheet
The supraglacial hydrological system of the Greenland Ice Sheet (GrIS) delivers ~60% of total mass loss from the ice sheet to the ocean (van den Broeke et al., 2016), making a thorough understanding crucial for sea level rise predictions. Supraglacial lakes play a crucial role in the evolution of …
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Evidence for the Drainage of a Superglacial Lake as the Source of Seismic Waves Recorded at a Regional Distance
… on the Greenland Ice Sheet surface, known as supraglacial lakes. Some of these lakes drain through cracks in their beds and release the water into the ice sheet. Previous studies suggest that some of the water reaches the bedrock, enabling basal sliding, which could potentially increase …
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Spatio-temporal variability and energy-balance implications of surface ponds on Himalayan debris-covered glaciers
… and field methods to assess the distribution of supraglacial ponds in the Langtang Valley of Nepal, then develops and applies numerical models of pond surface energy balance to determine energy receipts at the pond, glacier, and basin scales. 172 Landsat TM/ETM+ scenes are analysed to identify …
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Seasonal and interannual variability in the hydrology and geochemistry of an outlet glacier of the Greenland Ice Sheet
… flow tracer of distributed system drainage. Supraglacial meltwater runoff estimated using two independent models was compared with ice velocity measurements across the glacier’s catchment. Major spikes of Jdis occurred after rapid supraglacial meltwater runoff inputs and during the expansion …
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Modelling the impact of surface melt on the hydrology and dynamics of the Greenland Ice Sheet
… Three new models are presented: an updated supraglacial hydrology model incorporating moulin and crevasse drainage, along with lake drainage over the ice surface via channel incision; an ice sheet model implementing a numerically efficient formulation of ice flow; an adjoint code of the ice …
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Seasonal and interannual variability in the hydrology and geochemistry of an outlet glacier of the Greenland Ice Sheet
… flow tracer of distributed system drainage. Supraglacial meltwater runoff estimated using two independent models was compared with ice velocity measurements across the glacier's catchment. Major spikes of Jdis, occurred after rapid supraglacial meltwater runoff inputs and during the expansion …
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Marine-terminating outlet glacier response to hydrological mechanisms: A comparative study at Store Glestcher and Rink Isbrae, Uummannaq Bay, West Greenland
… of hydrological processes via surface runoff and supraglacial lake drainage. There has been increasing evidence for the influence of enhanced meltwater inputs on impacting short term velocity at marine-terminating outlet glaciers with contrasting responses at individual glaciers. This study uses a …
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Glacier Monitoring in Ladakh and Zanskar, northwestern India
… in the Himalaya are often heavily covered with supraglacial debris, making them difficult to study with remotely-sensed imagery alone. Various methods such as band ratios can be used effectively to map clean-ice glaciers; however, a thicker layer of debris often makes it impossible to …
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