Nicholson, Lindsey
2018-10-08
<p>This repository contains:</p>
<ul>
<li>2 files of measurements of supraglacial debris thickness at two sites (Gokyo and Margin) on the surface of the Ngozumpa Glacier (27°57′N, 85°42′E), Nepal, made using ground penetrating radar (GPR)</li>
<li>1 file of supplementary supraglacial thickness measurements from additional glacier sites using various methods</li>
<li>All files are comma separated text files</li>
</ul>
<p>Description of Ngozumpa GPR data:</p>
<ul>
<li>GPR measurements were made between 31<sup>st</sup> March and 20<sup>th</sup> April 2016.</li>
<li>Debris thickness was sampled in 36 individual radar transects, covering sloping and level terrain with coarse and fine surface material. The GPR system was a dual frequency 200/600MHz IDS RIS One, mounted on a small plastic sled and drawn along the surface.</li>
<li>Data were collected to a Lenovo Thinkpad using the IDS K2 FastWave software. </li>
<li>The 200 and 600 MHz antennas have separation distances of 0.230 m and 0.096 m respectively.</li>
<li>Data acquisition used a continuous step size, a time window of 100 ms and a digitization interval of 0.024 ns.</li>
<li>The location of the GPR system was recorded simultaneously at 1 s intervals by a low precision GPS integrated with the IDS which assigns a GPS location and time directly to every twelfth GPR trace, and by a more accurate differential GPS (dGPS) system consisting of a Trimble XH and Tornado antenna mounted on the GPR and a local base station of a Trimble Geo7X and Zephyr antenna.</li>
<li>Radargrams were processed in REFLEXW (Sandmeier software)</li>
<li>The reflection at the ice surface was picked manually wherever it was clearly identifiable and was not picked if it was indistinct.</li>
<li>The appropriate signal velocity for the supraglacial debris was obtained by burying a 1.5 m long steel bar to a known depth and then passing the GPR over the buried target and picking the two-way travel time to its reflection. Both fine and coarse material gave similar wave speeds (0.15 and 0.16 m ns<sup>-1</sup>), the average of which was used for all the radar lines measured</li>
</ul>
<p>Description of supplementary data:</p>
<ul>
<li>C1: Ngozumpa glacier (Nepal) about 1km from the terminus, measured using a theodolite survey (Nicholson and Benn, 2012)</li>
<li>C2: Ngozumpa glacier (Nepal) about 7km from the terminus, measured using a theodolite survey (Nicholson and Benn, 2012)</li>
<li>C3: Ngozumpa glacier (Nepal) about 3km from the terminus, measured using a photogrammetric survey (Nicholson and Mertes, 2017)</li>
<li>C4: Lirung glacier (Nepal), measured with GPR (McCarthy and others 2016)</li>
<li>C5: Suldenferner (Italy), measured with GPR (del Gobbo, 2017)</li>
<li>C6: Suldenferner (Italy), measured by excavation of debris (del Gobbo, 2017)</li>
<li>C7: Arolla glacier, (Switzerland), measured by excavation of debris (Reid and others, 2012)</li>
</ul>
<p>Details of these datasets can be found in the following publications:</p>
<p>Nicholson, L. I. and Benn, D. I.: Properties of natural supraglacial debris in relation to modelling sub-debris ice ablation, Earth Surf. Process. Landforms, 38(5), 409–501, doi:10.1002/esp.3299, 2012.</p>
<p>Nicholson, L. I. and Mertes, J. R.: Thickness estimation of supraglacial debris above ice cliff exposures using a high-resolution digital surface model derived from terrestrial photography, J. Glaciol., 1–10, doi:10.1017/jog.2017.68, 2017</p>
<p>McCarthy, M., Pritchard, H. D., Willis, I. and King, E.: Ground-penetrating radar measurements of debris thickness on Lirung Glacier, Nepal, J. Glaciol., 63(239), 534–555, doi:10.1017/jog.2017.18, 2017.</p>
<p>del Gobbo, C.: Debris thickness investigation of Solda glacier, southern Rhaetian Alps, Italy: Methodological considerations about the use of ground penetrating radar over a debris-covered glacier. MSc Thesis, University of Innsbruck, 2017.</p>
<p>Reid, T. D., Carenzo, M., Pellicciotti, F. and Brock, B. W.: Including debris cover effects in a distributed model of glacier ablation, J. Geophys. Res., 117(D18), 1–15, doi:10.1029/2012JD017795, 2012.</p>
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https://doi.org/10.5281/zenodo.1451560
oai:zenodo.org:1451560
Zenodo
https://zenodo.org/communities/acinn
https://doi.org/10.5281/zenodo.1451559
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Supraglacial debris thickness data from Ngozumpa Glacier, Nepal
info:eu-repo/semantics/other