scholarly journals A fine-scale digital elevation model of Antarctica derived from ICESat-2

2021 ◽  
Author(s):  
Xiaoyi Shen ◽  
Chang-Qing Ke ◽  
Yubin Fan ◽  
Lhakpa Drolma
Keyword(s):  
Ice Sheet ◽  
Fine Scale ◽  
Specific Time ◽  
Scientific Applications ◽  
Laser Altimeter ◽  
Ice Shelves ◽  
Digital Elevation ◽  
Time Stamps ◽  
Stereo Photogrammetry ◽  
Elevation Model

Abstract. Antarctic digital elevation models (DEMs) are essential for human fieldwork, ice topography monitoring and ice mass change estimation. In the past thirty decades, several Antarctic DEMs derived from satellite data have been published. However, these DEMs either have coarse spatial resolutions or vague time stamps, which limit their further scientific applications. In this study, the new-generation satellite laser altimeter Ice, Cloud, And Land Elevation Satellite-2 (ICESat-2) is used to generate a fine-scale and specific time-stamped Antarctic DEM for both the ice sheet and ice shelves. Approximately 4.69 × 109 ICESat-2 measurement points from November 2018 to November 2019 are used to estimate surface elevations at resolutions of 250 m, 500 m and 1 km based on a spatiotemporal fitting method, which results in a modal resolution of 250 m for this DEM. Approximately 74 % of Antarctica is observed, and the remaining observation gaps are interpolated using the ordinary kriging method. National Aeronautics and Space Administration Operation IceBridge (OIB) airborne data are used to evaluate the generated Antarctic DEM (hereafter called the ICESat-2 DEM) in individual Antarctic regions and surface types. Overall, a median bias of 0.11 m and a root-mean-square deviation of 8.27 m result from approximately 1.4 × 105 spatiotemporally matched grid cells. The accuracy and uncertainty of the ICESat-2 DEM vary in relation to the surface slope and roughness, and more reliable estimates are found in the flat ice sheet interior. The ICESat-2 DEM is superior to previous DEMs derived from satellite altimeters for both spatial resolution and elevation accuracy and comparable to those derived from stereo-photogrammetry and interferometry. The decimeter-scale accuracy and specific time stamp make the ICESat-2 DEM an essential addition to the existing Antarctic DEM groups, and it can be further used for other scientific applications.

scholarly journals A new digital elevation model of Antarctica derived from CryoSat-2 altimetry

2018 ◽  
Vol 12 (4) ◽  
pp. 1551-1562 ◽  
Author(s):  
Thomas Slater ◽  
Andrew Shepherd ◽  
Malcolm McMillan ◽  
Alan Muir ◽  
Lin Gilbert ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Ice Sheet ◽  
Grid Cells ◽  
Radar Altimeter ◽  
Laser Altimeter ◽  
Ice Shelves ◽  
Digital Elevation ◽  
Spatio Temporal ◽  
Satellite Radar ◽  
Elevation Model

Abstract. We present a new digital elevation model (DEM) of the Antarctic ice sheet and ice shelves based on 2.5×108 observations recorded by the CryoSat-2 satellite radar altimeter between July 2010 and July 2016. The DEM is formed from spatio-temporal fits to elevation measurements accumulated within 1, 2, and 5 km grid cells, and is posted at the modal resolution of 1 km. Altogether, 94 % of the grounded ice sheet and 98 % of the floating ice shelves are observed, and the remaining grid cells north of 88∘ S are interpolated using ordinary kriging. The median and root mean square difference between the DEM and 2.3×107 airborne laser altimeter measurements acquired during NASA Operation IceBridge campaigns are −0.30 and 13.50 m, respectively. The DEM uncertainty rises in regions of high slope, especially where elevation measurements were acquired in low-resolution mode; taking this into account, we estimate the average accuracy to be 9.5 m – a value that is comparable to or better than that of other models derived from satellite radar and laser altimetry.

scholarly journals A new Digital Elevation Model of Antarctica derived from CryoSat-2 altimetry

2017 ◽  
Author(s):  
Thomas Slater ◽  
Andrew Shepherd ◽  
Malcolm McMillan ◽  
Alan Muir ◽  
Lin Gilbert ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Ice Sheet ◽  
Grid Cells ◽  
Radar Altimeter ◽  
Laser Altimeter ◽  
Ice Shelves ◽  
Digital Elevation ◽  
Spatio Temporal ◽  
Satellite Radar ◽  
Elevation Model

Abstract. We present a new Digital Elevation Model (DEM) of the Antarctic ice sheet and ice shelves based on 2.5 × 108 observations recorded by the CryoSat-2 satellite radar altimeter between July 2010 and July 2016. The DEM is formed from spatio-temporal fits to elevation measurements accumulated within 1, 2 and 5 km grid cells, and is posted at the modal resolution of 1 km. Altogether, 94 % of the grounded ice sheet and 98 % of the floating ice shelves are observed, and the remaining grid cells North of 88° S are interpolated using ordinary kriging. The median and root mean square difference between the DEM and 2.3 × 107 airborne laser altimeter measurements acquired during NASA Operation IceBridge campaigns are −0.30 m and 13.50 m, respectively. The DEM uncertainty rises in regions of high slope – especially where elevation measurements were acquired in Low Resolution Mode – and, taking this into account, we estimate the average accuracy to be 9.5 m – a value that is comparable to or better than that of other models derived from satellite radar and laser altimetry.

scholarly journals A new 1 km digital elevation model of Antarctica derived from combined radar and laser data – Part 2: Validation and error estimates

2009 ◽  
Vol 3 (1) ◽  
pp. 113-123 ◽  
Author(s):  
J. A. Griggs ◽  
J. L. Bamber
Keyword(s):  
Digital Elevation Model ◽  
Satellite Data ◽  
Ice Sheet ◽  
Multiple Linear Regression Model ◽  
Altimeter Data ◽  
Laser Altimeter ◽  
Digital Elevation ◽  
Surface Slopes ◽  
Wide Range ◽  
Elevation Model

Abstract. We have developed a new digital elevation model (DEM) of Antarctica from a combination of satellite radar and laser altimeter data. Here, we assess the accuracy of the DEM by comparison with airborne altimeter data from four campaigns covering a wide range of surface slopes and ice sheet regions. Root mean squared (RMS) differences varied from 4.75 m, when compared to a densely gridded airborne dataset over the Siple Coast region of West Antarctica to 33.78 m when compared to a more limited dataset over the Antarctic Peninsula where surface slopes are high and the across track spacing of the satellite data is relatively large. The airborne data sets were employed to produce an error map for the DEM by developing a multiple linear regression model based on the variables known to influence errors in the DEM. Errors were found to correlate highly with surface slope, roughness and density of satellite data points. Errors ranged from typically ~1 m over the ice shelves to between about 2 and 6 m for the majority of the grounded ice sheet. In the steeply sloping margins, along the Peninsula and mountain ranges the estimated error is several tens of metres. Less than 2% of the area covered by the satellite data had an estimated random error greater than 20 m.

scholarly journals A new 1 km digital elevation model of Antarctica derived from combined radar and laser data – Part 2: Validation and error estimates

2008 ◽  
Vol 2 (5) ◽  
pp. 843-872 ◽  
Author(s):  
J. A. Griggs ◽  
J. L. Bamber
Keyword(s):  
Digital Elevation Model ◽  
Satellite Data ◽  
Ice Sheet ◽  
Multiple Linear Regression Model ◽  
Altimeter Data ◽  
Laser Altimeter ◽  
Digital Elevation ◽  
Surface Slopes ◽  
Wide Range ◽  
Elevation Model

Abstract. We have developed a new digital elevation model (DEM) of Antarctica from a combination of satellite radar and laser altimeter data. Here, we assess the accuracy of the DEM by comparison with airborne altimeter data from four campaigns covering a wide range of surface slopes and ice sheet regions. RMS differences varied from 4.84 m, when compared to a densely gridded airborne dataset over the Siple Coast region of West Antarctica to 29.28 m when compared to a more limited dataset over the Antarctic Peninsula where surface slopes are high and the across track spacing of the satellite data is relatively large. The airborne data sets were employed to produce an error map for the DEM by developing a multiple linear regression model based on the variables known to influence errors in the DEM. Errors were found to correlate highly with surface slope, roughness and density of satellite data points. Errors ranged from typically ~1 m over the ice shelves to between about 4 and 10 m for the majority of the grounded ice sheet. In the steeply sloping margins, along the Peninsula and mountain ranges the estimated error is several tens of metres. Slightly less than 7% of the area covered by the satellite data had an estimated random error greater than 20 m.

scholarly journals Measurement of ice-sheet topography using satellite-radar interferometry

1996 ◽  
Vol 42 (140) ◽  
pp. 10-22 ◽  
Author(s):  
Ian Joughin ◽  
Dale Winebrenner ◽  
Mark Fahnestock ◽  
Ron Kwok ◽  
William Krabill
Keyword(s):  
Ice Sheets ◽  
Ice Sheet ◽  
Surface Displacement ◽  
Horizontal Resolution ◽  
Radar Interferometry ◽  
Altimeter Data ◽  
Laser Altimeter ◽  
Digital Elevation ◽  
Satellite Radar ◽  
Ice Sheet Topography

AbstractDetailed digital elevation models (DEMs) do not exist for much of the Greenland and Antartic ice sheets. Radar altimetry is at present the primary, in many cases the only, source of topographic data over the ice sheets, but the horizontal resolution of such data is coarse. Satellite-radar interferometry uses the phase difference between pairs of synthetic aperture radar (SAR) images to measure both ice-sheet topography and surface displacement. We have applied this technique using ERS-1 SAR data to make detailed (i.e. 80 m horizontal resolution) maps of surface topography in a 100 km by 300 km strip in West Greenland, extending northward from just above Jakobshavns Isbræ. Comparison with а 76 km long line of airborne laser-altimeter data shows that We have achieved a relative accuracy of 2.5 m along the profile. These observations provide a detailed view of dynamically Supported topography near the margin of an ice sheet. In the final section We compare our estimate of topography with phase contours due to motion, and confirm our earlier analysis concerning vertical ice-sheet motion and complexity in ERS-1 SAR interferograms.

scholarly journals Bathymetric Photogrammetry to Update CHS Charts: Comparing Conventional 3D Manual and Automatic Approaches

2018 ◽  
Vol 7 (10) ◽  
pp. 395 ◽  
Author(s):  
René Chénier ◽  
Marc-André Faucher ◽  
Ryan Ahola ◽  
Yask Shelat ◽  
Mesha Sagram
Keyword(s):  
Hybrid Approach ◽  
Safe Navigation ◽  
Coastline Change ◽  
Digital Elevation ◽  
Stereo Photogrammetry ◽  
Global Matching ◽  
Elevation Model ◽  
Almost All ◽  
Depth Ranges ◽  
Remote Sensing Methods

The Canadian Hydrographic Service (CHS) supports safe navigation within Canadian waters through approximately 1000 navigational charts as well as hundreds of publications. One of the greatest challenges faced by the CHS is removing gaps in bathymetric survey data, particularly in the Canadian Arctic where only 6% of navigational water is surveyed to modern standards. Therefore, the CHS has initiated a research project to explore remote sensing methods to improve Canadian navigational charts. The major components of this project explore satellite derived bathymetry (SDB), coastline change detection and coastline extraction. This paper focuses on the potential of two stereo satellite techniques for deriving SDB: (i) automatic digital elevation model (DEM) extraction using a semi-global matching method, and (ii) 3D manual delineation of depth contours using visual stereoscopic interpretation. Analysis focused on quantitative assessment which compared estimated depths from both automatic and 3D manual photogrammetric approaches against available in situ survey depths. The results indicate that the 3D manual approach provides an accuracy of < 2 m up to a depth of 15 m. Comparable results were obtained from the automatic approach to a depth of 12 m. For almost all investigated depth ranges for both techniques, uncertainties were found to be within the required vertical accuracies for the International Hydrographic Organization category zone of confidence (CATZOC) level C classification for hydrographic surveys. This indicates that both techniques can be used to derive navigational quality bathymetric information within the investigated study site. While encouraging, neither technique was found to offer a single solution for the complete estimation of depth within the study area. As a result of these findings, the CHS envisions a hybrid approach where stereo- and reflectance-based bathymetry estimation techniques are implemented to provide the greatest understanding of depth possible from satellite imagery. Overall, stereo photogrammetry techniques will likely allow for new potential for supporting the improvement of CHS charts in areas where modern surveys have not yet been obtained.

scholarly journals A new bed elevation dataset for Greenland

2013 ◽  
Vol 7 (2) ◽  
pp. 499-510 ◽  
Author(s):  
J. L. Bamber ◽  
J. A. Griggs ◽  
R. T. W. L. Hurkmans ◽  
J. A. Dowdeswell ◽  
S. P. Gogineni ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Surface Elevation ◽  
The Arctic ◽  
Ice Thickness ◽  
Data Sampling ◽  
Ice Dynamics ◽  
Bed Elevation ◽  
Digital Elevation ◽  
Arctic Ice ◽  
Elevation Model

Abstract. We present a new bed elevation dataset for Greenland derived from a combination of multiple airborne ice thickness surveys undertaken between the 1970s and 2012. Around 420 000 line kilometres of airborne data were used, with roughly 70% of this having been collected since the year 2000, when the last comprehensive compilation was undertaken. The airborne data were combined with satellite-derived elevations for non-glaciated terrain to produce a consistent bed digital elevation model (DEM) over the entire island including across the glaciated–ice free boundary. The DEM was extended to the continental margin with the aid of bathymetric data, primarily from a compilation for the Arctic. Ice thickness was determined where an ice shelf exists from a combination of surface elevation and radar soundings. The across-track spacing between flight lines warranted interpolation at 1 km postings for significant sectors of the ice sheet. Grids of ice surface elevation, error estimates for the DEM, ice thickness and data sampling density were also produced alongside a mask of land/ocean/grounded ice/floating ice. Errors in bed elevation range from a minimum of ±10 m to about ±300 m, as a function of distance from an observation and local topographic variability. A comparison with the compilation published in 2001 highlights the improvement in resolution afforded by the new datasets, particularly along the ice sheet margin, where ice velocity is highest and changes in ice dynamics most marked. We estimate that the volume of ice included in our land-ice mask would raise mean sea level by 7.36 m, excluding any solid earth effects that would take place during ice sheet decay.

scholarly journals Improving maps of ice-sheet surface elevation change using combined laser altimeter and stereoscopic elevation model data

2013 ◽  
Vol 59 (215) ◽  
pp. 524-532 ◽  
Author(s):  
J.F. Levinsen ◽  
I.M. Howat ◽  
C.C. Tscherning
Keyword(s):  
Point Clouds ◽  
Altimeter Data ◽  
Laser Altimeter ◽  
Registration Errors ◽  
Digital Elevation ◽  
Surface Elevation Change ◽  
Laser Altimeters ◽  
Elevation Changes ◽  
Elevation Model ◽  
Spot 5

AbstractWe combine the complementary characteristics of laser altimeter data and stereoscopic digital elevation models (DEMs) to construct high-resolution (∼100 m) maps of surface elevations and elevation changes over rapidly changing outlet glaciers in Greenland. Measurements from spaceborne and airborne laser altimeters have relatively low errors but are spatially limited to the ground tracks, while DEMs have larger errors but provide spatially continuous surfaces. The principle of our method is to fit the DEM surface to the altimeter point clouds in time and space to minimize the DEM errors and use that surface to extrapolate elevations away from altimeter flight lines. This reduces the DEM registration errors and fills the gap between the altimeter paths. We use data from ICESat and ATM as well as SPOT 5 DEMs from 2007 and 2008 and apply them to the outlet glaciers Jakobshavn Isbræ (JI) and Kangerdlugssuaq (KL). We find that the main trunks of JI and KL lowered at rates of 30–35 and 7–20 m a−1,respectively. The rates decreased inland. The corresponding errors were 0.3–5.2 m a−1for JI and 0.3–5.1 m a−1for KL, with errors increasing proportionally with distance from the altimeter paths.

scholarly journals GIS dataset: geomorphological record of terrestrial-terminating ice streams, southern sector of Baltic Ice Stream Complex, last Scandinavian Ice Sheet, Poland

2021 ◽  
Author(s):  
Izabela Szuman ◽  
Jakub Z. Kalita ◽  
Marek W. Ewertowski ◽  
Chris D. Clark ◽  
Stephen J. Livingstone ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Ice Streams ◽  
Southern Sector ◽  
Ice Stream ◽  
Digital Elevation ◽  
Scandinavian Ice Sheet ◽  
Data Source ◽  
Elevation Model ◽  
The Baltic ◽  
The Last Glacial

Abstract. Here we present a comprehensive dataset of glacial geomorphological features covering an area of 65 000 km2 in central west Poland, located along the southern sector of the last Scandinavian Ice Sheet, within the limits of the Baltic Ice Stream Complex. The GIS dataset is based on mapping from a 0.4 m high-resolution Digital Elevation Model derived from airborne Light Detection and Ranging data. Ten landform types have been mapped: Mega-Scale Glacial Lineations, drumlins, marginal features (moraine chains, abrupt margins, edges of ice-contact fans), ribbed moraines, tunnel valleys, eskers, geometrical ridge networks and hill-hole pairs. The map comprises 5461 individual landforms or landform parts, which are available as vector layers in GeoPackage format at http://doi.org/10.5281/zenodo.4570570 (Szuman et al., 2021a). These features constitute a valuable data source for reconstructing and modelling the last Scandinavian Ice Sheet extent and dynamics from the Middle Weichselian Scandinavian Ice Sheet advance, 50–30 ka BP, through the Last Glacial Maximum, 25–21 ka BP and Young Baltic Advances, 18–15 ka BP. The presented data are particularly useful for modellers, geomorphologists and glaciologists.

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