Blar i forfatter "Holt, Tom O."

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    • Modification of bedrock surfaces by glacial abrasion and quarrying: Evidence from North Wales 

      Glasser, Neil F.; Roman, Matej; Holt, Tom O.; Žebre, Manja; Patton, Henry; Hubbard, Alun Lloyd (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-30)
      Abrasion and quarrying are significant processes of subglacial erosion for ice masses in direct contact with hard substrates, yet their relative efficacy and spatio-temporal variability is unclear. Here, we investigate the glacial impact of these processes on a 70 m by 60 m bedrock surface at Moel Ysgyfarnogod in the Rhinog Mountains, Wales, using a combination of high-resolution digital photographs, ...

    • 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 ...

    • UAV photogrammetry and structure from motion to assess calving dynamics at Store Glacier, a large outlet draining the Greenland ice sheet 

      Ryan, Johnny C.; Hubbard, Alun Lloyd; Box, Jason E.; Todd, Joe; Christoffersen, Poul; Carr, J. Rachel; Holt, Tom O.; Snooke, Neal A. (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-01-06)
      This study presents the application of a costeffective, unmanned aerial vehicle (UAV) to investigate calving dynamics at a major marine-terminating outlet glacier draining the western sector of the Greenland ice sheet. The UAV was flown over Store Glacier on three sorties during summer 2013 and acquired over 2000 overlapping, geotagged images of the calving front at an ∼ 40 cm ground sampling ...