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Supraglacial debris thickness data from Ngozumpa Glacier, Nepal

Nicholson, Lindsey


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    <subfield code="a">&lt;p&gt;This repository contains:&lt;/p&gt;

&lt;ul&gt;
	&lt;li&gt;2 files of measurements of supraglacial debris thickness at two sites (Gokyo and Margin) on the surface of the Ngozumpa Glacier (27&amp;deg;57&amp;prime;N, 85&amp;deg;42&amp;prime;E), Nepal, made using ground penetrating radar (GPR)&lt;/li&gt;
	&lt;li&gt;1 file of supplementary supraglacial thickness measurements from additional glacier sites using various methods&lt;/li&gt;
	&lt;li&gt;All files are comma separated text files&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Description of Ngozumpa GPR data:&lt;/p&gt;

&lt;ul&gt;
	&lt;li&gt;GPR measurements were made between 31&lt;sup&gt;st&lt;/sup&gt; March and 20&lt;sup&gt;th&lt;/sup&gt; April 2016.&lt;/li&gt;
	&lt;li&gt;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.&lt;/li&gt;
	&lt;li&gt;Data were collected to a Lenovo Thinkpad using the IDS K2 FastWave software.&amp;nbsp;&lt;/li&gt;
	&lt;li&gt;The 200 and 600&amp;nbsp;MHz antennas have separation distances of 0.230&amp;nbsp;m and 0.096&amp;nbsp;m respectively.&lt;/li&gt;
	&lt;li&gt;Data acquisition used a continuous step size, a time window of 100 ms and a digitization interval of 0.024 ns.&lt;/li&gt;
	&lt;li&gt;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.&lt;/li&gt;
	&lt;li&gt;Radargrams were processed in REFLEXW (Sandmeier software)&lt;/li&gt;
	&lt;li&gt;The reflection at the ice surface was picked manually wherever it was clearly identifiable and was not picked if it was indistinct.&lt;/li&gt;
	&lt;li&gt;The appropriate signal velocity for the supraglacial debris was obtained by burying a 1.5&amp;nbsp;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&lt;sup&gt;-1&lt;/sup&gt;), the average of which was used for all the radar lines measured&lt;/li&gt;
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&lt;p&gt;Description of supplementary data:&lt;/p&gt;

&lt;ul&gt;
	&lt;li&gt;C1: Ngozumpa glacier (Nepal) about 1km from the terminus, measured using a theodolite survey (Nicholson and Benn, 2012)&lt;/li&gt;
	&lt;li&gt;C2: Ngozumpa glacier (Nepal) about 7km from the terminus, measured using a theodolite survey (Nicholson and Benn, 2012)&lt;/li&gt;
	&lt;li&gt;C3: Ngozumpa glacier (Nepal) about 3km from the terminus, measured using a photogrammetric survey (Nicholson and Mertes, 2017)&lt;/li&gt;
	&lt;li&gt;C4: Lirung glacier (Nepal), measured with GPR (McCarthy and others 2016)&lt;/li&gt;
	&lt;li&gt;C5: Suldenferner (Italy), measured with GPR (del Gobbo, 2017)&lt;/li&gt;
	&lt;li&gt;C6: Suldenferner (Italy), measured by excavation of debris (del Gobbo, 2017)&lt;/li&gt;
	&lt;li&gt;C7: Arolla glacier, (Switzerland), measured by excavation of debris (Reid and others, 2012)&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Details of these datasets can be found in the following publications:&lt;/p&gt;

&lt;p&gt;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&amp;ndash;501, doi:10.1002/esp.3299, 2012.&lt;/p&gt;

&lt;p&gt;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&amp;ndash;10, doi:10.1017/jog.2017.68, 2017&lt;/p&gt;

&lt;p&gt;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&amp;ndash;555, doi:10.1017/jog.2017.18, 2017.&lt;/p&gt;

&lt;p&gt;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.&lt;/p&gt;

&lt;p&gt;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&amp;ndash;15, doi:10.1029/2012JD017795, 2012.&lt;/p&gt;

&lt;p&gt;&amp;nbsp;&lt;/p&gt;

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