DOI: 10.18738/t8/m77ank
title: NSF COLDEX Ice Penetrating Radar Derived Grids of the Southern Flank of Dome A
title: Ice thickness, bed elevation, specularity content, subglacial RMS deviation, surface elevation and fractional basal ice thickness

description: &lt;p&gt;NSF COLDEX performed two airborne campaigns from South Pole Station over the Southern Flank of Dome A and 2022-23 and 2023-24, searching for a potential site of a continuous ice core that could sample the mid-Pleistocene transition. Ice thickness data extracted from the MARFA radar system has allow for a new understanding of this region.&lt;/p&gt;

&lt;p&gt;Here we generate crustal scale maps of ice thickness, bed elevation, specularity content, subglacial RMS deviation, surface elevation and fractional basal ice thickness with 1 km sampling, and 10 km resolution. We include both masked and unmasked grids.&lt;/p&gt;

&lt;p&gt; The projection is in the SCAR standard ESPG:3031 polar stereographic projection with true scale at 71˚S.&lt;/p&gt;

&lt;p&gt;These geotiffs were generated using performed using GMT6.5 (&lt;a href="https://doi.org/10.1029/2019GC008515"&gt;Wessel et al., 2019&lt;/a&gt;) using the pygmt interface, by binning the raw data to 2.5 km cells, and using the &lt;a href="https://github.com/sakov/nn-c"&gt; nnbathy &lt;/a&gt; program to apply natural neighbor interpolation to 1 km sampling. A 10 km Gaussian filter - representing typical lines spacings - was applied and then a mask was applied for all locations where the nearest data point was further than 8 km. &lt;/p&gt;

Ice thickness, bed elevation and RMS deviation @ 400 m length scale (&lt;a href="http://dx.doi.org/10.1029/2000JE001429"&gt;roughness&lt;/a&gt;) data includes the following datasets:
&lt;ul&gt;
&lt;li&gt; UTIG/CRESIS &lt;a href="https://doi.org/10.18738/T8/J38CO5"&gt;NSF COLDEX Airborne MARFA data&lt;/a&gt;&lt;/li&gt;
&lt;li&gt; British Antarctic Survey &lt;a href="https://doi.org/10.5285/0f6f5a45-d8af-4511-a264-b0b35ee34af6"&gt;AGAP-North&lt;/a&gt;&lt;/li&gt;
&lt;li&gt; LDEO &lt;a href="https://doi.org/10.1594/IEDA/317765"&gt; AGAP-South &lt;/a&gt;&lt;/li&gt;
&lt;li&gt; British Antarctic Survey &lt;a href="https://doi.org/10.5270/esa-8ffoo3e"&gt;Polargap&lt;/a&gt;&lt;/li&gt;
&lt;li&gt; UTIG Support Office for Airborne Research &lt;a href="https://doi.org/10.15784/601588"&gt;Pensacola-Pole Transect (PPT) &lt;/a&gt;&lt;/li&gt;
&lt;li&gt; NASA/CReSIS &lt;a href="https://doi.org/10.5067/GDQ0CUCVTE2Q"&gt; 2016 and 2018 Operation Ice Bridge &lt;/a&gt; &lt;/li&gt;
&lt;li&gt; ICECAP/PRIC &lt;a href="https://doi.org/10.15784/601437"&gt; SPICECAP Titan Dome Survey &lt;/a&gt;
&lt;/ul&gt;

&lt;p&gt;Specularity content (&lt;a href="https://doi.org/10.1109/LGRS.2014.2337878"&gt;Schroeder et al. 2014&lt;/a&gt;) is compiled from &lt;a href="https://doi.org/10.18738/T8/KHUT1U"&gt; Young et al. 2025a &lt;/a&gt; and &lt;a href="https://doi.org/10.18738/T8/6T5JS6"&gt; Young et al. 2025b&lt;/a&gt;.&lt;/p&gt;

&lt;p&gt;Basal ice fractional thickness is complied from manual interpretation by Vega González, Yan and Singh. &lt;/p&gt;

&lt;p&gt; Surface elevations is derived by combining the following datasets:
&lt;ul&gt;
&lt;li&gt; UTIG &lt;a href="https://doi.org/10.18738/T8/99IEOG"&gt; 2022-23 &lt;/a&gt; and &lt;a href="https://doi.org/10.18738/T8/PNBFOL"&gt; 2023-24 &lt;/a&gt; NSF COLDEX laser altimetry data &lt;/li&gt;
&lt;li&gt; BAS &lt;a href="https://doi.org/10.5285/d55e87dd-a74d-4182-be99-93ab805103ab"&gt; 2015-16 &lt;/a&gt; Polargap laser altimetry data (used for the surface in the bed elevation pick data)&lt;/li&gt;
&lt;li&gt; SOAR &lt;a href="https://doi.org/10.18738/T8/QMEWFA"&gt; 1998-99 &lt;/a&gt; Pensacola-Pole Transect laser altimetry data &lt;/li&gt;
&lt;li&gt; ICECAP &lt;a href="https://doi.org/10.15784/601437"&gt; 2016-17 &lt;/a&gt; SPICECAP laser altimetry data &lt;/li&gt;
&lt;li&gt; NASA &lt;a href="https://doi.org/10.5067/ATLAS/ATL14.004"&gt; 2019-2024 &lt;/a&gt; ICESat-2/ATLAS gridded surface elevation data (north of 88˚S)&lt;/li&gt;
&lt;/ul&gt;


&lt;p&gt;Code to generated these grids can be found at &lt;a href="https://github.com/smudog/COLDEX_dichotomy_paper_2025"&gt; at github.com &lt;/a&gt;&lt;/p&gt;