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EARTH SCIENCE > Hydrosphere > Glaciers/Ice Sheets > Glacier Thickness/Ice Sheet Thickness

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  • Analysis of surface elevation, bed topography and ice thickness across the Bailey/Slessor region of East Antarctica using data from the BEDMAP project.

  • Airborne radio-echo sounding (RES) measurements of surface elevation, bed topography and ice thickness were made across the Bailey/Slessor region of East Antarctica. The primary objective of this research was to investigate the newly discovered complex flow in a region of the interior of the East Antarctic Ice Sheet. To do this, the surface, englacial and basal flow regime of a region of complex flow associated with the upper part of the Bailey/Slessor glacier system was investigated using 150 MHz airborne radio-echo sounding (RES) equipment mounted on the airborne survey Twin Otter aircraft. The effective along track sampling interval = 25 m and across track spacing = 40 km.

  • Gravity data acquired in the region of subglacial Lake Ellsworth. Instrument Lacoste & Romberg land gravity meter. Drift control primarily contained within the local area. Single, one-way tie to international gravity base station network (Rothera). Single survey line ~30 km long. Station spacing 2 km, except for 240 m spacing over the lake. Position, elevation, ice- and water-thickness data exist for each station.

  • Ground-penetrating radar (GPR) was used to test glacier ice thickness/glacier bed detectability on debris-covered Himalayan glaciers at a range of frequencies in glacier long- and cross- profiles and at static points. The survey sites were of the Lirung and Langtang Glaciers in the Langtang National Park, Nepal, where debris cover thickness varied from centimetres to several metres. The radar used was the BAS DELORES dipole pulse radar system, operating at 5MHz, 10MHz, 20MHZ and 40MHz. Data were acquired as a stop-go survey at 2-4m intervals on partially snow-covered and entirely debris-covered glacier surfaces in temperatures close to freezing, with a diurnal freeze-thaw cycle. Funding was provided by the NERC grant NE/L013258/1.

  • This dataset presents the input and output data from a set of sensitivity experiments to simulate the evolution of the Laurentide ice sheet in the Early Holocene (10-7 thousand years ago). These data are presented in the manuscript "Simulating the Early Holocene demise of the Laurentide Ice Sheet with BISICLES (public trunk revision 3298)". Simulating the demise of the Laurentide Ice Sheet covering the Hudson Bay in the early Holocene is important for understanding the role of accelerated changes in ice sheet topography and melt in the ''8.2 ka event'', a century long cooling of the Northern Hemisphere by several degrees. Freshwater released from the ice sheet through a surface mass balance instability (known as the saddle collapse) has been suggested as a major forcing for the 8.2 ka event, but the temporal evolution of this pulse has not been constrained. Dynamical ice loss and marine interactions could have significantly accelerated the ice sheet demise, but simulating such processes requires computationally expensive models that are difficult to configure and are often impractical for simulating past ice sheets. Here, we developed an ice sheet model setup for studying the Laurentide Ice Sheet''s Hudson Bay saddle collapse and the associated meltwater pulse in unprecedented detail using the BISICLES ice sheet model, an efficient marine ice sheet model of the latest generation, capable of refinement to kilometre-scale resolution and higher-order ice flow physics. The setup draws on previous efforts to model the deglaciation of the North American Ice Sheet for initialising the ice sheet temperature, recent ice sheet reconstructions for developing the topography of the region and ice sheet, and output from a general circulation model for a representation of the climatic forcing. The modelled deglaciation is in agreement with the reconstructed extent of the ice sheet and the associated meltwater pulse has realistic timing. Furthermore, the peak magnitude of the modelled meltwater equivalent (0.07-0.13 Sv) is compatible with geological estimates of freshwater discharge through the Hudson Strait. The results demonstrate that while improved representation of the glacial dynamics and marine interactions are key for correctly simulating the pattern of early Holocene ice sheet retreat, surface mass balance introduces by far the most uncertainty. The new model configuration presented here provides future opportunities to quantify the range of plausible amplitudes and durations of a Hudson Bay ice saddle collapse meltwater pulse and its role in forcing the 8.2 ka event. Ilkka Matero was funded by the Leeds-York Natural Environment Research Council (NERC) Spheres Doctoral Training Partnership (NE/L002574/1). The contribution from Ruza Ivanovic was partly supported by NERC grant NE/K008536/1. Lauren Gregoire is funded by a UKRI Future Leaders Fellowship (MR/S016961/1). The work made use of the N8 HPC facilities, which are provided and funded by the N8 consortium and EPSRC (EP/K000225/1) and co-ordinated by the Universities of Leeds and Manchester.