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1. NSF COLDEX 2023-24 Level 2 Basal Specularity Content Profiles

   https://doi.org/10.18738/T8/KHUT1U  

   Young, Duncan; Kerr, Megan E; Singh, Shivangini; Yan, Shuai; Kempf, Scott D; Ng, Gregory; Blankenship, Donald D; Young, Duncan (January 2025, Texas Data Repository)

   <p><b> Introduction </b> <br> The National Science Foundations Center for Oldest Ice Exploration (<a href="https://www.coldex.org">NSF COLDEX</a>) is a Science and Technology Center working to extend the record of atmospheric gases, temperature and ice sheet history to greater than 1 million years. As part of this effort, NSF COLDEX has been searching for a site for a continuous ice core extending through the mid-Pleistocene transition. Two seasons of airborne survey were conducted from South Pole Station across the southern flank of Dome A. </p> <p><b> 2023-2024 Field Season </b> <br> In the 2023-2024 field season (CXA2), and using a BT-67 Basler, NSF COLDEX conducted 17 flights from South Pole Station toward the southern flank of Dome C. Three test flights were conducted from McMurdo Station. Instrumentation included the <a href="https://doi.org/10.18738/T8/J38CO5">60 MHz MARFA ice penetrating radar </a> from the University of Texas Institute for Geophysics, a <a href="https://doi.org/10.1109/IGARSS53475.2024.10640448">UHF ice penetrating radar </a> from the Center for Remote Sensing and Integrated Systems; an GT-2 Gravimeter, and LD-90 laser altimeter and an G-823 Magnetometer. </p> <p><b> Basal specularity content </b> <br> These basal specularity content were derived from comparing 1D and 2D focused MARFA data (<a href="http://doi.org/10.1109/TGRS.2007.897416">Peters et al., 2007</a>). By comparing bed echo strengths for different focusing apertures, and accounting for the ranges and angles involved, we can derive the "specularity content" of the bed echo, a proxy for small scale bed roughness and a good indicator for subglacial water pressure in regions of distributed subglacial water (<a href="https://doi.org/10.1109/LGRS.2014.2337878">Schroeder et al., 2014, IEEE GRSL </a>, <a href="https://doi.org/10.1016/j.epsl.2019.115961">Dow et al., 2019, EPSL </a>) and smooth deforming bed material (<a href="http://doi.org/10.1002/2014GL061645">Schroeder et al., 2014, GRL</a>, <a href="http://dx.doi/org/10.1098/rsta.2014.0297">Young et al., 2016, PTRS</a>. Specularity data are inherently noisy, so these products have been smoothed with a 1 km filter.</p> 

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2. NSF COLDEX 2022-23 Level 2 Basal Specularity Content Profiles

   https://doi.org/10.18738/T8/6T5JS6  

   Young, Duncan; Kerr, Megan E; Singh, Shivangini; Yan, Shuai; Kempf, Scott D; Ng, Gregory; Blankenship, Donald D; Young, Duncan (January 2025, Texas Data Repository)

   <p><b> Introduction </b> <br> The National Science Foundations Center for Oldest Ice Exploration (<a href="https://www.coldex.org">NSF COLDEX</a>) is a Science and Technology Center working to extend the record of atmospheric gases, temperature and ice sheet history to greater than 1 million years. As part of this effort, NSF COLDEX has been searching for a site for a continuous ice core extending through the mid-Pleistocene transition. Two seasons of airborne survey were conducted from South Pole Station across the southern flank of Dome A. </p> <p><b> 2022-2023 Field Season </b> <br> In the 2022-20223 field season (CXA1), and using a BT-67 Basler, NSF COLDEX conducted 13 full flights and one weather abort from South Pole Station toward the southern flank of Dome C; as well as 1 survey flight toward Hercules Dome in support of the Hercules Dome Drilling project. Three test flights were conducted from McMurdo Station. Instrumentation included the <a href="https://doi.org/10.18738/T8/J38CO5">60 MHz MARFA ice penetrating radar </a> from the University of Texas Institute for Geophysics, a <a href="https://doi.org/10.1109/IGARSS53475.2024.10640448">UHF ice penetrating radar </a> from the Center for Remote Sensing and Integrated Systems; an GT-2 Gravimeter, and LD-90 laser altimeter and an G-823 Magnetometer. </p> <p><b> Basal specularity content </b> <br> These basal specularity content were derived from comparing 1D and 2D focused MARFA data (<a href="http://doi.org/10.1109/TGRS.2007.897416">Peters et al., 2007</a>). By comparing bed echo strengths for different focusing apertures, and accounting for the ranges and angles involved, we can derive the "specularity content" of the bed echo, a proxy for small scale bed roughness and a good indicator for subglacial water pressure in regions of distributed subglacial water (<a href="https://doi.org/10.1109/LGRS.2014.2337878">Schroeder et al., 2014, IEEE GRSL </a>, <a href="https://doi.org/10.1016/j.epsl.2019.115961">Dow et al., 2019, EPSL </a>) and smooth deforming bed material (<a href="http://doi.org/10.1002/2014GL061645">Schroeder et al., 2014, GRL</a>, <a href="http://dx.doi/org/10.1098/rsta.2014.0297">Young et al., 2016, PTRS</a>. Specularity data are inherently noisy, so these products have been smoothed with a 1 km filter.</p> 

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3. NSF COLDEX Ice Penetrating Radar Derived Grids of the Southern Flank of Dome A:Subtitle

   https://doi.org/10.18738/T8/M77ANK  

   Young, Duncan A; Paden, John P; Yan, Shuai; Kerr, Megan E; Singh, Shivangini; Vega_Gonzàlez, Alejandra; Kaundinya, Shravan; Greenbaum, Jamin S; Chan, Kristian; Blankenship, Donald D; et al (January 2025, Texas Data Repository)

   <p>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.</p> <p>Here we generate crustal scale maps of ice thickness, bed elevation, specularity content, subglacial RMS deviation and fractional basal ice thickness with 1 km sampling, and 10 km resolution. We include both masked and unmasked grids.</p> <p> The projection is in the SCAR standard ESPG:3031 polar stereographic projection with true scale at 71˚S.</p> <p>These geotiffs were generated using performed using GMT6.5 (<a href="https://doi.org/10.1029/2019GC008515">Wessel et al., 2019</a>) using the pygmt interface, by binning the raw data to 2.5 km cells, and using the <a href="https://github.com/sakov/nn-c"> nnbathy </a> 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. </p> Ice thickness, bed elevation and RMS deviation @ 400 m length scale (<a href="http://dx.doi.org/10.1029/2000JE001429">roughness</a>) data includes the following datasets: <ul> <li> UTIG/CRESIS <a href="https://doi.org/10.18738/T8/J38CO5">NSF COLDEX Airborne MARFA data</a></li> <li> British Antarctic Survey <a href="https://doi.org/10.5285/0f6f5a45-d8af-4511-a264-b0b35ee34af6">AGAP-North</a></li> <li> LDEO <a href="https://doi.org/10.1594/IEDA/317765"> AGAP-South </a></li> <li> British Antarctic Survey <a href="https://doi.org/10.5270/esa-8ffoo3e">Polargap</a></li> <li> UTIG Support Office for Airborne Research <a href="https://doi.org/10.15784/601588">Pensacola-Pole Transect (PPT) </a></li> <li> NASA/CReSIS <a href="https://doi.org/10.5067/GDQ0CUCVTE2Q"> 2016 and 2018 Operation Ice Bridge </a> </li> <li> ICECAP/PRIC <a href="https://doi.org/10.15784/601437"> SPICECAP Titan Dome Survey </a> </ul> <p>Specularity content (<a href="https://doi.org/10.1109/LGRS.2014.2337878">Schroeder et al. 2014</a>) is compiled from <a href="https://doi.org/10.18738/T8/KHUT1U"> Young et al. 2025a </a> and <a href="https://doi.org/10.18738/T8/6T5JS6"> Young et al. 2025b</a>.</p> <p>Basal ice fractional thickness is complied from manual interpretation by Vega Gonzàlez, Yan and Singh. </p> <p>Code to generated these grids can be found at <a href="https://github.com/smudog/COLDEX_dichotomy_paper_2025"> at github.com </a></p> 

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4. ESCHER ice thickness, echo strength and specularity content data for the Exploration of Saline Cryospheric Habitats with Europa Relevance project

   https://doi.org/10.18738/T8/ZN15UF  

   Blankenship, Donald; Beem, Lucas H; Pierce, Christopher; Buhl, Dillon P; Skidmore, Mark; Kempf, Scott D (January 2024, Texas Data Repository)

   ESCHER (Exploration of Saline Cryospheric Habitats with Europa Relevance) is a NASA funded PSTAR (Planetary Science and Technology from Analog Research) program with the general geophysical goals of characterizing the subglacial environment of Devon Ice Cap in Nunavut, Canada as a potential planetary analog. The project seeks to gather additional evidence for unique chemistry in the subglacial hydrological system and to further the technical development of the scientific instrumentation. ESCHER represents the first field deployment of a multi-polarization radar system on an A-Star 350 B2 helicopter platform. This is the sixth polar deployment of this helicopter geophysical system, and the first in the arctic. The previous helicopter-based systems expeditions were KRT1, KRT2, ASE2, ASE3, ASE4. Similar results for ASE3 are described in Pierce et al, 2023, and Pierce et al, 2024. The science goals include characterizing the subglacial environment from the summit of Devon Ice Cap to Sverdrup Glacier’s marine termination. The study area includes three linked geographical regions: i) The summit area where Rutishauser et al. (2020), presented further evidence for the existence of fluid at the base of Devon Ice Cap; ii) the shoulder region of the ice cap, just upstream of the ice flow that enters the outlet valleys of Fox and Sverdrup Glaciers. This region includes the hypothesized distributed hydrological system that transitions into channelized geometry, and iii) The Sverdrup/Fox valley glaciers, tidewater terminus, and locations of subglacial discharge. The study region also includes the upper catchment of the Crocker Bay Glaciers and some of the western land terminating flanks of the ice cap. All data in this collection is derived from a multipolarization version of the Helicopter Radar (HERA) system (Lindzey et al., 2017, 2022). Included in this dataset are the Level 2 time registered geophysical observables for the specific lines mentioned in Pierce et al., (2024); ice thickness, partial bed reflectivity, surface reflectivity, bed and surface elevation derived both from incoherent processing (IR2HI2) and focused processing (IRFOC2; Peters et al., 2007); no multipolarization processing is included here. Also included is specularity content (IRSPC2; Schroeder et al., 2014, Young et al, 2016). Data consists of ASCII tab delimited tables, with header describing the columns and key metadata on a per transect basis. Images showing simple maps of values are also included. The following transects are included: DEV3/PER0a/Y79a DEV3/PER0a/Y80a DEV3/PER0a/Y81a DEV3/PER0a/Y82a DEV3/PER0a/Y83a DEV3/PER0a/Y84a DEV3/PER0a/Y85a DEV3/PER0a/Y86a DEV3/PER0a/Y87a References: Pierce, C., 2024, Advanced Analysis of the Sub-Glacial Environment Using Radar Echo Sounding Simulations, Ph. D. Thesis, Montana State University Pierce, C., Gerekos, C., Skidmore, M., Beem, L., Blankenship, D., Lee, W. S., Adams, E., Lee, C.-K., and Stutz, J., 2024, Characterizing sub-glacial hydrology using radar simulations, The Cryosphere, 18, 4, 1495--1515, 10.5194/tc-18-1495-2024 Pierce, C., Skidmore, M., Beem, L., Blankenship, D., Adams, E., and Gerekos, C., 2024, Exploring canyons beneath Devon Ice Cap for sub-glacial drainage using radar and thermodynamic modeling, Journal Of Glaciology, 1--18, 10.1017/jog.2024.49 Lindzey, L., Quartini, E., Buhl, D., Blankenship, D., Richter, T., Greenbaum, J., and Young, D., 2017, KRT1/LGV1 Season Field Report, 237 10.26153/tsw/11620 Lindzey, L. E., Beem, L. H., Young, D. A., Quartini, E., Blankenship, D. D., Lee, C.-K., Lee, W. S., Lee, J. I., and Lee, J., 2020, Aerogeophysical characterization of an active subglacial lake system in the David Glacier catchment, Antarctica, The Cryosphere, 14, 7, 2217--2233, 10.5194/tc-14-2217-2020 Peters, M. E., Blankenship, D. D., Carter, S. P., Young, D. A., Kempf, S. D., and Holt, J. W., 2007, Along-track Focusing of Airborne Radar Sounding Data From West Antarctica for Improving Basal Reflection Analysis and Layer Detection, IEEE Transactions On Geoscience And Remote Sensing, 45, 9, 2725-2736, 10.1109/TGRS.2007.897416Rutishauser, A., Blankenship, D. D., Young, D. A., Wolfenbarger, N. S., Beem, L. H., Skidmore, M. L., Dubnick, A., and Criscitiello, A. S., 2022, Radar sounding survey over Devon Ice Cap indicates the potential for a diverse hypersaline subglacial hydrological environment, The Cryosphere, 16, 379-395, https://doi.org/10.5194/tc-16-379-2022 Schroeder, D. M., Blankenship, D. D., Raney, R. K., and Grima, C., 2015, Estimating subglacial water geometry using radar bed echo specularity: application to Thwaites Glacier, West Antarctica, IEEE Geoscience And Remote Sensing Letters, 12, 3, 443-447, 10.1109/LGRS.2014.2337878 Young, D. A., Schroeder, D. M., Blankenship, D. D., Kempf, S. D., and Quartini, E., 2016, The distribution of basal water between Antarctic subglacial lakes from radar sounding, Philosophical Transactions Of The Royal Society A, 374, 20140297, 1-21, 10.1098/rsta.2014.0297 

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5. Warm Core Ring Trajectories in the Northwest Atlantic Slope Sea (2000-2010)

   https://doi.org/10.5281/zenodo.7406675  

   Porter, Nicholas; Silver, Adrienne; Gangopadhyay, Avijit (January 2022, Zenodo)

   {"Abstract":["This dataset consists of weekly trajectory information of Gulf Stream Warm Core Rings from 2000-2010. This work builds upon Silver et al. (2022a) ( https://doi.org/10.5281/zenodo.6436380) which contained Warm Core Ring trajectory information from 2011 to 2020. Combining the two datasets a total of 21 years of weekly Warm Core Ring trajectories can be obtained. An example of how to use such a dataset can be found in Silver et al. (2022b).<\/p>\n\nThe format of the dataset is similar to that of  Silver et al. (2022a), and the following description is adapted from their dataset. This dataset is comprised of individual files containing each ring\u2019s weekly center location and its area for 374 WCRs present between January 1, 2000 and December 31, 2010. Each Warm Core Ring is identified by a unique alphanumeric code 'WEyyyymmddA', where 'WE' represents a Warm Eddy (as identified in the analysis charts); 'yyyymmdd' is the year, month and day of formation; and the last character 'A' represents the sequential sighting of the eddies in a particular year. Continuity of a ring which passes from one year to the next is maintained by the same character in the first sighting.  For example, the first ring in 2002 having a trailing alphabet of 'F' indicates that five rings were carried over from 2001 which were still observed on January 1, 2002. Each ring has its own netCDF (.nc) filename following its alphanumeric code. Each file contains 4 variables, \u201cLon\u201d- the ring center\u2019s weekly longitude, \u201cLat\u201d- the ring center\u2019s weekly latitude, \u201cArea\u201d - the rings weekly size in km^{2<\/sup>, and \u201cDate\u201d in days - representing the days since Jan 01, 0000. <\/p>\n\n}The process of creating the WCR tracking dataset follows the same methodology of the previously generated WCR census (Gangopadhyay et al., 2019, 2020). The Jenifer Clark\u2019s Gulf Stream Charts used to create this dataset are 2-3 times a week from 2000-2010. Thus, we used approximately 1560 Charts for the 10 years of analysis. All of these charts were reanalyzed between 75° and 55°W using QGIS 2.18.16 (2016) and geo-referenced on a WGS84 coordinate system (Decker, 1986). <\/p>\n\n <\/p>\n\nSilver, A., Gangopadhyay, A, & Gawarkiewicz, G. (2022a). Warm Core Ring Trajectories in the Northwest Atlantic Slope Sea (2011-2020) (1.0.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.6436380<\/p>\n\nSilver, A., Gangopadhyay, A., Gawarkiewicz, G., Andres, M., Flierl, G., & Clark, J. (2022b). Spatial Variability of Movement, Structure, and Formation of Warm Core Rings in the Northwest Atlantic Slope Sea. Journal of Geophysical Research: Oceans<\/em>, 127<\/em>(8), e2022JC018737. https://doi.org/10.1029/2022JC018737 <\/p>\n\nGangopadhyay, A., G. Gawarkiewicz, N. Etige, M. Monim and J. Clark, 2019. An Observed Regime Shift in the Formation of Warm Core Rings from the Gulf Stream, Nature - Scientific Reports, https://doi.org/10.1038/s41598-019-48661-9. www.nature.com/articles/s41598-019-48661-9.<\/p>\n\nGangopadhyay, A., N. Etige, G. Gawarkiewicz, A. M. Silver, M. Monim and J. Clark, 2020.  A Census of the Warm Core Rings of the Gulf Stream (1980-2017). Journal of Geophysical Research, Oceans, 125, e2019JC016033. https://doi.org/10.1029/2019JC016033.<\/p>\n\nQGIS Development Team. QGIS Geographic Information System (2016).<\/p>\n\nDecker, B. L. World Geodetic System 1984. World geodetic system 1984 (1986).<\/p>\n\n <\/p>"],"Other":["Funded by two NSF US grants OCE-1851242, OCE-212328","{"references": ["Silver, A., Gangopadhyay, A, & Gawarkiewicz, G. (2022). Warm Core Ring Trajectories in the Northwest Atlantic Slope Sea (2011-2020) (1.0.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.6436380", "Silver, A., Gangopadhyay, A., Gawarkiewicz, G., Andres, M., Flierl, G., & Clark, J. (2022b). Spatial Variability of Movement, Structure, and Formation of Warm Core Rings in the Northwest Atlantic Slope Sea.\\u00a0Journal of Geophysical Research: Oceans,\\u00a0127(8), e2022JC018737.\\u00a0https://doi.org/10.1029/2022JC018737", "Gangopadhyay, A., G. Gawarkiewicz, N. Etige, M. Monim and J. Clark, 2019. An Observed Regime Shift in the Formation of Warm Core Rings from the Gulf Stream, Nature - Scientific Reports, https://doi.org/10.1038/s41598-019-48661-9. www.nature.com/articles/s41598-019-48661-9.", "Gangopadhyay, A., N. Etige, G. Gawarkiewicz, A. M. Silver, M. Monim and J. Clark, 2020. A Census of the Warm Core Rings of the Gulf Stream (1980-2017). Journal of Geophysical Research, Oceans, 125, e2019JC016033. https://doi.org/10.1029/2019JC016033.", "QGIS Development Team. QGIS Geographic Information System (2016).", "Decker, B. L. World Geodetic System 1984. World geodetic system 1984 (1986)."]}"]} 

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