ORCID Profile
0000-0002-6866-8176
Current Organisation
The University of Texas at Austin
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Publisher: Copernicus GmbH
Date: 05-05-2017
Abstract: Abstract. Digital elevation models of Antarctic bed topography are smoothed and interpolated onto low-resolution ( 1 km) grids as current observed topography data are generally sparsely and unevenly s led. This issue has potential implications for numerical simulations of ice-sheet dynamics, especially in regions prone to instability where detailed knowledge of the topography, including fine-scale roughness, is required. Here, we present a high-resolution (100 m) synthetic bed elevation terrain for Antarctica, encompassing the continent, continental shelf, and seas south of 60° S. Although not identically matching observations, the synthetic bed surface – denoted as HRES – preserves topographic roughness characteristics of airborne and ground-based ice-penetrating radar data measured by the ICECAP (Investigating the Cryospheric Evolution of the Central Antarctic Plate) consortium or used to create the Bedmap1 compilation. Broad-scale ( 5 km resolution) features of the Antarctic landscape are incorporated using a low-pass filter of the Bedmap2 bed elevation data. HRES has applicability in high-resolution ice-sheet modelling studies, including investigations of the interaction between topography, ice-sheet dynamics, and hydrology, where processes are highly sensitive to bed elevations and fine-scale roughness. The data are available for download from the Australian Antarctic Data Centre (doi:10.4225/15/57464ADE22F50).
Publisher: Copernicus GmbH
Date: 14-08-2017
Abstract: Abstract. A high-resolution (1 km line spacing) aerogeophysical survey was conducted over a region near the East Antarctic Ice Sheet's Dome C that may hold a 1.5 Myr climate record. We combined new ice thickness data derived from an airborne coherent radar sounder with unpublished data that was in part unavailable for earlier compilations, and we were able to remove older data with high positional uncertainties. We generated a revised high-resolution digital elevation model (DEM) to investigate the potential for an old ice record in this region, and used laser altimetry to confirm a Cryosat-2 derived DEM for inferring the glaciological state of the candidate area. By measuring the specularity content of the bed, we were able to find an additional 50 subglacial lakes near the candidate site, and by Doppler focusing the radar data, we were able to map out the roughness of the bed at length scales of hundreds of meters. We find that the primary candidate region contains elevated rough topography interspersed with scattered subglacial lakes and some regions of smoother bed. Free subglacial water appears to be restricted from bed overlain by ice thicknesses of less than 3000 m. A site near the ice ide was selected for further investigation. The high resolution of this ice thickness data set also allows us to explore the nature of ice thickness uncertainties in the context of radar geometry and processing.
Publisher: Springer Science and Business Media LLC
Date: 12-12-2019
Publisher: Copernicus GmbH
Date: 22-11-2022
Publisher: Copernicus GmbH
Date: 09-07-2020
Abstract: Abstract. We present a topographic digital elevation model (DEM) for Princess Elizabeth Land (PEL), East Antarctica – the last remaining region in Antarctica to be surveyed by airborne radio-echo sounding (RES) techniques. The DEM covers an area of ~900,000 km2 and was established from new RES data collected by the ICECAP-2 consortium, led by the Polar Research Institute of China, from four c aigns since 2015. Previously, the region (along with Recovery basin elsewhere in East Antarctica) was characterised by an inversion using low resolution satellite gravity data across a large ( km wide) data-free zone to generate the Bedmap2 topographic product. We use the mass conservation (MC) method to produce an ice thickness grid across faster-flowing ( m yr-1) regions of the ice sheet and streamline diffusion in slower-flowing areas. The resulting ice thickness model is integrated with an ice surface model to build the bed DEM. With the revised bed DEM, we are able to model the flow of subglacial water and assess where the hydraulic pressure, and hydrological routing, is most sensitive to small ice-surface gradient changes. Together with BedMachine Antarctica, and Bedmap2, this new PEL bed DEM completes the first order measurement of subglacial continental Antarctica – an international mission that began around 70 years ago. The ice thickness and bed elevation DEMs of PEL (resolved horizontally at 500 m relative to ice surface elevations obtained from a combination of European Remote Sensing Satellite 1 radar (ERS-1) and Ice, Cloud and Land Elevation Satellite (ICESat) laser satellite altimetry datasets) are accessible from 0.5281/zenodo.3666088 (Cui et 38al., 2020).
Publisher: Copernicus GmbH
Date: 04-05-2018
DOI: 10.5194/TC-2018-80
Abstract: Abstract. Previous studies of Totten Ice Shelf have employed surface velocity measurements to estimate its mass balance and understand its sensitivities to interannual changes in climate forcing. However, displacement measurements acquired over timescales of days to weeks may not accurately characterize long-term flow rates where ice velocity fluctuates with the seasons. Quantifying annual mass budgets or analyzing interannual changes in ice velocity requires knowing when and where observations of glacier velocity could be aliased by subannual variability. Here, we analyze 16 years of velocity data for Totten Ice Shelf, which we generate at subannual resolution by applying feature tracking algorithms to several hundred satellite image pairs. We identify a seasonal cycle characterized by a spring to autumn speedup of more than 100 m yr−1 close to the ice front. The litude of the seasonal cycle diminishes with distance from the open ocean, suggesting the presence of a resistive backstress at the ice front that is strongest in winter. Springtime acceleration precedes summer surface melt and is not attributable to thinning from basal melt. We attribute the onset of ice shelf acceleration each spring to the loss of buttressing from the breakup of seasonal landfast sea ice.
Publisher: Copernicus GmbH
Date: 20-07-2016
DOI: 10.5194/TC-2016-169
Abstract: Abstract. A high resolution (1 km line spacing) aerogeophysical survey was conducted over a region near the East Antarctic Ice Sheet's Dome C that may hold a 1.5 million year old climate record. New ice thickness data derived from an airborne coherent radar sounder was combined with unpublished data that was unavailable for earlier compilations. We find under the primary candidate region elevated rough topography, near a number of subglacial lakes, but also regions of smoother bed. The high resolution of this ice thickness dataset also allows us to explore the nature of ice thickness uncertainties in the context of radar geometry and processing.
Publisher: Wiley
Date: 21-09-2020
Publisher: Elsevier BV
Date: 06-2021
Publisher: American Geophysical Union (AGU)
Date: 06-07-2018
DOI: 10.1029/2018GL078153
Publisher: Wiley
Date: 24-03-2020
Publisher: American Geophysical Union (AGU)
Date: 10-2020
DOI: 10.1029/2020JB019825
Publisher: American Geophysical Union (AGU)
Date: 03-2012
DOI: 10.1029/2011JF002066
Publisher: Springer Science and Business Media LLC
Date: 06-2011
DOI: 10.1038/NATURE10114
Abstract: The first Cenozoic ice sheets initiated in Antarctica from the Gamburtsev Subglacial Mountains and other highlands as a result of rapid global cooling ∼34 million years ago. In the subsequent 20 million years, at a time of declining atmospheric carbon dioxide concentrations and an evolving Antarctic circumpolar current, sedimentary sequence interpretation and numerical modelling suggest that cyclical periods of ice-sheet expansion to the continental margin, followed by retreat to the subglacial highlands, occurred up to thirty times. These fluctuations were paced by orbital changes and were a major influence on global sea levels. Ice-sheet models show that the nature of such oscillations is critically dependent on the pattern and extent of Antarctic topographic lowlands. Here we show that the basal topography of the Aurora Subglacial Basin of East Antarctica, at present overlain by 2-4.5 km of ice, is characterized by a series of well-defined topographic channels within a mountain block landscape. The identification of this fjord landscape, based on new data from ice-penetrating radar, provides an improved understanding of the topography of the Aurora Subglacial Basin and its surroundings, and reveals a complex surface sculpted by a succession of ice-sheet configurations substantially different from today's. At different stages during its fluctuations, the edge of the East Antarctic Ice Sheet lay pinned along the margins of the Aurora Subglacial Basin, the upland boundaries of which are currently above sea level and the deepest parts of which are more than 1 km below sea level. Although the timing of the channel incision remains uncertain, our results suggest that the fjord landscape was carved by at least two iceflow regimes of different scales and directions, each of which would have over-deepened existing topographic depressions, reversing valley floor slopes.
Publisher: Copernicus GmbH
Date: 03-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-1809
Abstract: & & The Princess Elizabeth Land (PEL) sector of the East Antarctic Ice Sheet, one of the largest grounded ice reservoirs in Antarctica, is adjacent to regions that experienced significant change during the last glacial maximum. The identification of subglacial water in PEL (to date only inferred from satellite image data) would provide important constraints on our estimation of the basal thermal condition in this region. Also, the existence of a large subglacial hydrology system in PEL comes with potential impacts on the basal melting rate and stability of downstream ice shelves, such as the West Ice Shelf. Here we present geophysical evidences confirming the existence of a large subglacial lake in PEL, hereby referred as Lake Snow Eagle (LSE), for the first time, using recently acquired aerogeophyscial data by international collaborations. We estimate LSE to be about 42 km in length and 370 km& sup& & /sup& in area, making it one of the largest subglacial lakes in Antarctica. LSE is shown to lie in a subglacial canyon system that is linked to the coastal ice shelves, which makes LSE the first known major Antarctic interior water body that has a potential direct hydrological pathway into the ocean. We then systematically investigate its geological characteristics and bathymetry by 2-D geophysics modellings. We estimate the water volume of LSE to be about 21 km& sup& & /sup& , while the sediment volume to be about 20 km& sup& & /sup& . Our geophysical modelling results also suggest that LSE is located along a compressional geologic boundary, indicating possible tectonic controls over LSE.& &
Publisher: Copernicus GmbH
Date: 17-07-2023
DOI: 10.5194/ESSD-15-2695-2023
Abstract: Abstract. One of the key components of this research has been the mapping of Antarctic bed topography and ice thickness parameters that are crucial for modelling ice flow and hence for predicting future ice loss and the ensuing sea level rise. Supported by the Scientific Committee on Antarctic Research (SCAR), the Bedmap3 Action Group aims not only to produce new gridded maps of ice thickness and bed topography for the international scientific community, but also to standardize and make available all the geophysical survey data points used in producing the Bedmap gridded products. Here, we document the survey data used in the latest iteration, Bedmap3, incorporating and adding to all of the datasets previously used for Bedmap1 and Bedmap2, including ice bed, surface and thickness point data from all Antarctic geophysical c aigns since the 1950s. More specifically, we describe the processes used to standardize and make these and future surveys and gridded datasets accessible under the Findable, Accessible, Interoperable, and Reusable (FAIR) data principles. With the goals of making the gridding process reproducible and allowing scientists to re-use the data freely for their own analysis, we introduce the new SCAR Bedmap Data Portal (bedmap.scar.org, last access: 1 March 2023) created to provide unprecedented open access to these important datasets through a web-map interface. We believe that this data release will be a valuable asset to Antarctic research and will greatly extend the life cycle of the data held within it. Data are available from the UK Polar Data Centre: data.bas.ac.uk (last access: 5 May 2023). See the Data availability section for the complete list of datasets.
Publisher: Copernicus GmbH
Date: 06-09-2018
Abstract: Abstract. Previous studies of Totten Ice Shelf have employed surface velocity measurements to estimate its mass balance and understand its sensitivities to interannual changes in climate forcing. However, displacement measurements acquired over timescales of days to weeks may not accurately characterize long-term flow rates wherein ice velocity fluctuates with the seasons. Quantifying annual mass budgets or analyzing interannual changes in ice velocity requires knowing when and where observations of glacier velocity could be aliased by subannual variability. Here, we analyze 16 years of velocity data for Totten Ice Shelf, which we generate at subannual resolution by applying feature-tracking algorithms to several hundred satellite image pairs. We identify a seasonal cycle characterized by a spring to autumn speedup of more than 100 m yr−1 close to the ice front. The litude of the seasonal cycle diminishes with distance from the open ocean, suggesting the presence of a resistive back stress at the ice front that is strongest in winter. Springtime acceleration precedes summer surface melt and is not attributable to thinning from basal melt. We attribute the onset of ice shelf acceleration each spring to the loss of buttressing from the breakup of seasonal landfast sea ice.
Publisher: Copernicus GmbH
Date: 17-04-2018
Abstract: Abstract. We reconstruct the pattern of surface accumulation in the region around Dome C, East Antarctica, since the last glacial. We use a set of 18 isochrones spanning all observable depths of the ice column, interpreted from various ice-penetrating radar surveys and a 1-D ice flow model to invert for accumulation rates in the region. The shallowest four isochrones are then used to calculate paleoaccumulation rates between isochrone pairs using a 1-D assumption where horizontal advection is negligible in the time interval of each layer. We observe that the large-scale (100s km) surface accumulation gradient is spatially stable through the last 73 kyr, which reflects current modeled and observed precipitation gradients in the region. We also observe small-scale (10 s km) accumulation variations linked to snow redistribution at the surface, due to changes in its slope and curvature in the prevailing wind direction that remain spatially stationary since the last glacial.
Publisher: Copernicus GmbH
Date: 03-11-2015
Abstract: Abstract. Ice cores provide some of the best dated and most comprehensive proxy records, as they yield a vast and growing array of proxy indicators. Selecting a site for ice core drilling is nonetheless challenging, as the assessment of potential new sites needs to consider a variety of factors. Here, we demonstrate a systematic approach to site selection for a new East Antarctic high resolution ice core record. Specifically, seven criteria are considered: (1) 2000 year old ice at 300 m depth, (2) above 1000 m elevation, (3) a minimum accumulation rate of 250 mm yr−1 IE, (4) minimal surface re-working to preserve the deposited climate signal, (5) a site with minimal displacement or elevation change of ice at 300 m depth, (6) a strong teleconnection to mid-latitude climate and (7) an appropriately complementary relationship to the existing Law Dome record (a high resolution record in East Antarctica). Once assessment of these physical characteristics identified promising regions, logistical considerations (for site access and ice core retrieval) were briefly considered. We use Antarctic surface mass balance syntheses, along with ground-truthing of satellite data by airborne radar surveys to produce all-of-Antarctica maps of surface roughness, age at specified depth, elevation and displacement change and surface air temperature correlations to pinpoint promising locations. We also use the European Centre for Medium-Range Weather Forecast ERA 20th Century reanalysis (ERA-20C) to ensure a site complementary to the Law Dome record is selected. We find three promising sites in the Indian Ocean sector of East Antarctica in the coastal zone from Enderby Land to the Ingrid Christensen Coast (50–100° E). Although we focus on East Antarctica for a new ice core site, the methodology is more generally applicable and we include key parameters for all of Antarctica which may be useful for ice core site selection elsewhere and/or for other purposes.
Publisher: Copernicus GmbH
Date: 22-11-2022
Abstract: Abstract. Over the past 60 years, scientists have strived to understand the past, present and future of the Antarctic Ice Sheet. One of the key components of this research has been the mapping of Antarctic bed topography and ice thickness parameters that are crucial for modelling ice flow and hence for predicting future ice loss and ensuing sea level rise. Supported by the Scientific Committee on Antarctic Research (SCAR), the Bedmap3 Action Group aims not only to produce new gridded maps of ice thickness and bed topography for the international scientific community, but also to standardize and make available all the geophysical survey data points used in producing the Bedmap gridded products. Here, we document the survey data used in the latest iteration, Bedmap3, incorporating and adding to all of the datasets previously used for Bedmap1 and Bedmap2, including ice-bed, surface and thickness point data from all Antarctic geophysical c aigns since the 1950s. More specifically, we describe the processes used to standardize and make these and future survey and gridded datasets accessible under the ‘Findable, Accessible, Interoperable and Reusable’ (FAIR) data principles. With the goals to make the gridding process reproducible and to allow scientists to re-use the data freely for their own analysis, we introduce the new SCAR Bedmap Data Portal (bedmap.scar.org, last access: 18 October 2022) created to provide unprecedented open access to these important datasets, through a user-friendly webmap interface. We believe that this data release will be a valuable asset to Antarctic research and will greatly extend the life cycle of the data held within it. Data are available from the UK Polar Data Centre: data.bas.ac.uk.
Publisher: Copernicus GmbH
Date: 04-07-2016
DOI: 10.5194/ESSD-2016-18
Abstract: Abstract. Digital elevation models of Antarctic bed topography are heavily smoothed and interpolated onto low-resolution ( 1 km) grids as our current observed topography data are generally sparsely and unevenly s led. This issue has potential implications for numerical simulations of ice-sheet dynamics, especially in regions prone to instability where detailed knowledge of the topography, including fine-scale roughness, is required. Here, we present a high-resolution (100 m) synthetic bed elevation terrain for the whole Antarctic continent. The synthetic bed surface preserves topographic roughness characteristics of airborne and ground-based ice-penetrating radar data from the Bedmap1 compilation and the ICECAP consortium. Broad-scale features of the Antarctic landscape are incorporated using a low-pass filter of the Bedmap2 bed-elevation data. Although not intended as a substitute for Bedmap2, the simulated bed elevation terrain has applicability in high-resolution ice-sheet modelling studies, including investigations of the interaction between topography, ice-sheet dynamics, and hydrology, where processes are highly sensitive to bed elevations. The data are available for download at the Australian Antarctic Data Centre (doi:10.4225/15/57464ADE22F50).
Publisher: Copernicus GmbH
Date: 14-11-2020
DOI: 10.5194/ESSD-12-2765-2020
Abstract: Abstract. We present a topographic digital elevation model (DEM) for Princess Elizabeth Land (PEL), East Antarctica. The DEM covers an area of ∼900 000 km2 and was built from radio-echo sounding data collected during four c aigns since 2015. Previously, to generate the Bedmap2 topographic product, PEL's bed was characterized from low-resolution satellite gravity data across an otherwise large ( km wide) data-free zone. We use the mass conservation (MC) method to produce an ice thickness grid across faster flowing ( m yr−1) regions of the ice sheet and streamline diffusion in slower flowing areas. The resulting ice thickness model is integrated with an ice surface model to build the bed DEM. Together with BedMachine Antarctica and Bedmap2, this new bed DEM completes the first-order measurement of subglacial continental Antarctica – an international mission that began around 70 years ago. The ice thickness data and bed DEMs of PEL (resolved horizontally at 500 m relative to ice surface elevations obtained from the Reference Elevation Model of Antarctica – REMA) are accessible from 0.5281/zenodo.4023343 (Cui et al., 2020a) and 0.5281/zenodo.4023393 (Cui et al., 2020b).
Publisher: American Association for the Advancement of Science (AAAS)
Date: 30-11-2012
Abstract: Mass loss from the ice sheets of Greenland and Antarctica account for a large fraction of global sea-level rise. Part of this loss is because of the effects of warmer air temperatures, and another because of the rising ocean temperatures to which they are being exposed. Joughin et al. (p. 1172 ) review how ocean-ice interactions are impacting ice sheets and discuss the possible ways that exposure of floating ice shelves and grounded ice margins are subject to the influences of warming ocean currents. Estimates of the mass balance of the ice sheets of Greenland and Antarctica have differed greatly—in some cases, not even agreeing about whether there is a net loss or a net gain—making it more difficult to project accurately future sea-level change. Shepherd et al. (p. 1183 ) combined data sets produced by satellite altimetry, interferometry, and gravimetry to construct a more robust ice-sheet mass balance for the period between 1992 and 2011. All major regions of the two ice sheets appear to be losing mass, except for East Antarctica. All told, mass loss from the polar ice sheets is contributing about 0.6 millimeters per year (roughly 20% of the total) to the current rate of global sea-level rise.
Publisher: Copernicus GmbH
Date: 13-07-2011
Abstract: Abstract. Ice thickness data over much of East Antarctica are sparse and irregularly distributed. This poses difficulties for reconstructing the homogeneous coverage needed to properly assess underlying sub-glacial morphology and fundamental geometric constraints on sea level rise. Here we introduce a new physically-based ice thickness interpolation scheme and apply this to existing ice thickness data in the Aurora Subglacial Basin region. The skill and robustness of the new reconstruction is demonstrated by comparison with new data from the ICECAP project. The interpolated morphology shows an extensive marine-based ice sheet, with considerably more area below sea-level than shown by prior studies. It also shows deep features connecting the coastal grounding zone with the deepest regions in the interior. This has implications for ice sheet response to a warming ocean and underscores the importance of obtaining additional high resolution data in these marginal zones for modelling ice sheet evolution.
Publisher: Copernicus GmbH
Date: 08-03-2016
Abstract: Abstract. Ice cores provide some of the best-dated and most comprehensive proxy records, as they yield a vast and growing array of proxy indicators. Selecting a site for ice core drilling is nonetheless challenging, as the assessment of potential new sites needs to consider a variety of factors. Here, we demonstrate a systematic approach to site selection for a new East Antarctic high-resolution ice core record. Specifically, seven criteria are considered: (1) 2000-year-old ice at 300 m depth (2) above 1000 m elevation (3) a minimum accumulation rate of 250 mm years−1 IE (ice equivalent) (4) minimal surface reworking to preserve the deposited climate signal (5) a site with minimal displacement or elevation change in ice at 300 m depth (6) a strong teleconnection to midlatitude climate and (7) an appropriately complementary relationship to the existing Law Dome record (a high-resolution record in East Antarctica). Once assessment of these physical characteristics identified promising regions, logistical considerations (for site access and ice core retrieval) were briefly considered. We use Antarctic surface mass balance syntheses, along with ground-truthing of satellite data by airborne radar surveys to produce all-of-Antarctica maps of surface roughness, age at specified depth, elevation and displacement change, and surface air temperature correlations to pinpoint promising locations. We also use the European Centre for Medium-Range Weather Forecast ERA 20th Century reanalysis (ERA-20C) to ensure that a site complementary to the Law Dome record is selected. We find three promising sites in the Indian Ocean sector of East Antarctica in the coastal zone from Enderby Land to the Ingrid Christensen Coast (50–100° E). Although we focus on East Antarctica for a new ice core site, the methodology is more generally applicable, and we include key parameters for all of Antarctica which may be useful for ice core site selection elsewhere and/or for other purposes.
Publisher: Copernicus GmbH
Date: 03-11-2015
No related grants have been discovered for Duncan Young.