Blar i forfatter "Hubbard, Alun"

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    • Cascading lake drainage on the Greenland Ice Sheet triggered by tensile shock and fracture 

      Christoffersen, Poul; Bougamont, Marion; Hubbard, Alun; Doyle, Samuel H.; Grigsby, Shane; Pettersson, Rickard (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-03-14)
      Supraglacial lakes on the Greenland Ice Sheet are expanding inland, but the impact on ice flow is equivocal because interior surface conditions may preclude the transfer of surface water to the bed. Here we use a well-constrained 3D model to demonstrate that supraglacial lakes in Greenland drain when tensile-stress perturbations propagate fractures in areas where fractures are normally absent or ...

    • The extreme yet transient nature of glacial erosion 

      Patton, Henry; Hubbard, Alun; Heyman, J.; Alexandropoulou, Nikolitsa; Lasabuda, Amando P. E.; Stroeven, A.P.; Hall, A.M.; Winsborrow, Monica; Sugden, David E.; Kleman, J.; Andreassen, Karin Marie (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-11-30)
      Ice can sculpt extraordinary landscapes, yet the efficacy of, and controls governing, glacial erosion on geological timescales remain poorly understood and contended, particularly across Polar continental shields. Here, we assimilate geophysical data with modelling of the Eurasian Ice Sheet — the third largest Quaternary ice mass that spanned 49°N to 82°N — to decipher its erosional footprint during ...

    • Is there a Climatic Control on Icelandic Volcanism? 

      Cooper, Claire L.; Savov, Ivan P.; Patton, Henry; Hubbard, Alun; Ivanovic, Ruza F.; Carrivick, Jonathan L.; Swindles, Graeme T. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-07)
      The evidence for periods of increased volcanic activity following deglaciation, such as following ice sheet retreat after the Last Glacial Maximum, has been examined in several formerly glaciated areas, including Iceland, Alaska, and the Andean Southern Volcanic Zone. Here we present new evidence supporting the theory that during episodes of cooling in the Holocene, Icelandic volcanic activity ...

    • Seismic and electrical geophysical characterization of an incipient coastal open-system pingo: Lagoon Pingo, Svalbard 

      Hammock, Craig Paul; Kulessa, Bernd; Hiemstra, John F.; Hodson, Andrew; Hubbard, Alun (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-24)
      Whilst there has been a recent appreciation for the role of open-system pingos in providing a fluid-flow conduit through continuous permafrost that enables methane release, the formation and internal structure of these ubiquitous permafrost-diagnostic landforms remains unclear. Here, we combine active-source seismic measurements with electrical resistivity tomography (ERT) to investigate the structural ...

    • A steady-state model reconstruction of the patagonian ice sheet during the last glacial maximum 

      Wolff, Ingo W.; Glasser, Neil F.; Harrison, Stephan; Wood, Joanne Laura; Hubbard, Alun (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-07-17)
      During the Last Glacial Maximum (LGM), the Patagonian Ice Sheet (PIS) was the largest Quaternary ice mass in the Southern Hemisphere outside of Antarctica. Although the margins of the LGM ice sheet are now well established through end-moraine mapping and dating, apart from a few modelling and empirical studies, there remains a lack of constraint on its thickness and three-dimensional configuration. ...

    • Temporal Variability of Surface Reflectance Supersedes Spatial Resolution in Defining Greenland’s Bare-Ice Albedo 

      Irvine-Fynn, Tristram D. L.; Bunting, Peter S.; Cook, Joseph M.; Hubbard, Alun; Barrand, Nicholas E.; Hanna, Edward; Hardy, Andy J.; Hodson, Andrew J.; Holt, Tom O.; Huss, Matthias; McQuaid, James B.; Nilsson, Johan; Naegeli, Kathrin; Roberts, Osian; Ryan, Jonathan C.; Tedstone, Andrew J.; Tranter, Martyn; Williamson, Christopher J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-23)
      Ice surface albedo is a primary modulator of melt and runoff, yet our understanding of how reflectance varies over time across the Greenland Ice Sheet remains poor. This is due to a disconnect between point or transect scale albedo sampling and the coarser spatial, spectral and/or temporal resolutions of available satellite products. Here, we present time-series of bare-ice surface reflectance data ...

    • Widespread partial-depth hydrofractures in ice sheets driven by supraglacial streams 

      Chandler, David Matthew; Hubbard, Alun (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-19)
      Dramatic supraglacial lake drainage events in Greenland and Antarctica are enabled by rapid hydrofracture propagation through ice over 1 km thick. Here we present a slower mode of hydrofracture, where hairline surface fractures intersect supraglacial streams, and hypothesize that penetration depth is critically limited by water supply and englacial refreezing. We develop a model of stream-fed ...