scholarly journals A new 1 km digital elevation model of the Antarctic derived from combined satellite radar and laser data – Part 1: Data and methods

2008 ◽  
Vol 2 (5) ◽  
pp. 811-841 ◽  
Author(s):  
J. L. Bamber ◽  
J. L. Gomez-Dans ◽  
J. A. Griggs
Keyword(s):  
Surface Expression ◽  
Altimeter Data ◽  
Grid Cells ◽  
Satellite Mission ◽  
Laser Altimeter ◽  
Digital Elevation ◽  
Spatial Coverage ◽  
Laser Data ◽  
Vertical Accuracy ◽  
Satellite Radar

Abstract. Digital elevation models (DEMs) of Antarctica have been derived, previously, from satellite radar altimetry (SRA) and limited terrestrial data. Near the ice sheet margins and in other areas of steep relief the SRA data tend to have relatively poor coverage and accuracy. To remedy this and to extend the coverage beyond the latitudinal limit of the SRA missions (81.5° S) we have combined laser altimeter measurements from the Geosciences Laser Altimeter System onboard ICESat with SRA data from the geodetic phase of the ERS-1 satellite mission. The former provide decimetre vertical accuracy but with poor spatial coverage. The latter have excellent spatial coverage but a poorer vertical accuracy. By combining the radar and laser data using an optimal approach we have maximised the vertical accuracy and spatial resolution of the DEM and minimised the number of grid cells with an interpolated elevation estimate. We assessed the optimum resolution for producing a DEM based on a trade-off between resolution and interpolated cells, which was found to be 1 km. This resulted in just under 35% of grid cells having an interpolated value. The accuracy of the final DEM was assessed using a suite of independent airborne altimeter data and used to produce an error map. The RMS error in the new DEM was found to be roughly half that of the best previous 5 km resolution, SRA-derived DEM, with marked improvements in the steeper marginal and mountainous areas and between 81.5 and 86° S. The DEM contains a wealth of information related to ice flow. This is particularly apparent for the two largest ice shelves – the Filchner-Ronne and Ross – where the surface expression of flow of ice streams and outlet glaciers can be traced from the grounding line to the calving front. The surface expression of subglacial lakes and other basal features are also illustrated. We also use the DEM to derive new estimates of balance velocities and ice divide locations.

scholarly journals A new 1 km digital elevation model of the Antarctic derived from combined satellite radar and laser data – Part 1: Data and methods

2009 ◽  
Vol 3 (1) ◽  
pp. 101-111 ◽  
Author(s):  
J. L. Bamber ◽  
J. L. Gomez-Dans ◽  
J. A. Griggs
Keyword(s):  
Surface Expression ◽  
Altimeter Data ◽  
Grid Cells ◽  
Satellite Mission ◽  
Laser Altimeter ◽  
Digital Elevation ◽  
Spatial Coverage ◽  
Laser Data ◽  
Vertical Accuracy ◽  
Satellite Radar

Abstract. Digital elevation models (DEMs) of the whole of Antarctica have been derived, previously, from satellite radar altimetry (SRA) and limited terrestrial data. Near the ice sheet margins and in other areas of steep relief the SRA data tend to have relatively poor coverage and accuracy. To remedy this and to extend the coverage beyond the latitudinal limit of the SRA missions (81.5° S) we have combined laser altimeter measurements from the Geosciences Laser Altimeter System onboard ICESat with SRA data from the geodetic phase of the ERS-1 satellite mission. The former provide decimetre vertical accuracy but with poor spatial coverage. The latter have excellent spatial coverage but a poorer vertical accuracy. By combining the radar and laser data using an optimal approach we have maximised the vertical accuracy and spatial resolution of the DEM and minimised the number of grid cells with an interpolated elevation estimate. We assessed the optimum resolution for producing a DEM based on a trade-off between resolution and interpolated cells, which was found to be 1 km. This resulted in just under 32% of grid cells having an interpolated value. The accuracy of the final DEM was assessed using a suite of independent airborne altimeter data and used to produce an error map. The RMS error in the new DEM was found to be roughly half that of the best previous 5 km resolution, SRA-derived DEM, with marked improvements in the steeper marginal and mountainous areas and between 81.5 and 86° S. The DEM contains a wealth of information related to ice flow. This is particularly apparent for the two largest ice shelves – the Filchner-Ronne and Ross – where the surface expression of flow of ice streams and outlet glaciers can be traced from the grounding line to the calving front. The surface expression of subglacial lakes and other basal features are also illustrated. We also use the DEM to derive new estimates of balance velocities and ice divide locations.

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 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 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

Abstract Detailed 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 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 An Improved Digital Elevation Model of the Lunar Mons Rümker Region Based on Multisource Altimeter Data

2018 ◽  
Vol 10 (9) ◽  
pp. 1442 ◽  
Author(s):  
Fei Li ◽  
Chang Zhu ◽  
Weifeng Hao ◽  
Jianguo Yan ◽  
Mao Ye ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Ground Truth ◽  
Horizontal Resolution ◽  
Altimeter Data ◽  
Laser Altimeter ◽  
Lunar Landing ◽  
Data Processing Method ◽  
Digital Elevation ◽  
Lunar Reconnaissance Orbiter ◽  
Elevation Model

Mons Rümker is the primary candidate region for the lunar landing mission of Chang’E-5. We propose a data processing method that combines multisource altimeter data and we developed an improved digital elevation model (DEM) of the Mons Rümker region with a horizontal resolution of 256 pixels per degree. The lunar orbiter laser altimeter (LOLA) onboard the lunar reconnaissance orbiter (LRO) acquired 884 valid orbital benchmark data with a high precision. A special crossover adjustment of 156 orbital profiles from the Chang’E-1 laser altimeter (LAM) and 149 orbital profiles from the SELenological and ENgineering Explorer (SELENE) laser altimeter (LALT) was applied. The radial residual root mean square (RMS) of the LAM was reduced from 154.83 ± 43.60 m to 14.29 ± 27.84 m and that of the LALT was decreased from 3.50 ± 5.0 m to 2.75 ± 4.4 m. We used the adjusted LAM and LALT data to fill the LOLA gaps and created the merged LOLA + LAM and LOLA + LALT DEMs. The merged LOLA + LAM DEM showed distortions because of the horizontal geolocation errors in the LAM data. The merged LOLA + LALT DEM was closer to the ground truth than the LOLA-only DEM when validated with the images of the LRO camera (LROC).

The potential of TanDEM-X repeat acquisitions to monitor elevation and mass changes of Arctic and Antarctic glaciers

2021 ◽  
Author(s):  
Christian Sommer ◽  
Thorsten Seehaus ◽  
Lukas Sochor ◽  
Philipp Malz ◽  
Matthias Braun
Keyword(s):  
Antarctic Peninsula ◽  
Greenland Ice Sheet ◽  
The Arctic ◽  
Radar Signal ◽  
Altimeter Data ◽  
Satellite Mission ◽  
Laser Altimeter ◽  
North Asia ◽  
Elevation Changes ◽  
The Antarctic

<p>The large ice caps and glaciers of the northern and southern polar regions have the potential to contribute significantly to global sea-level rise, yet measurements of glacier mass changes in those regions are scarce and difficult due to harsh conditions and the size of Arctic and Antarctic glacier areas. Acquisitions of the synthetic aperture radar satellite mission TanDEM-X provide valuable insights into glacier dynamics in those regions as the X-band radar is independent from clouds and illumination and can resolve elevation changes of large glacierized areas as well as individual glaciers. We use specifically generated and coregistered digital elevation models (DEM) from repeated TanDEM-X data takes to derive glacier elevation changes between 2010 and 2020.</p><p>For the Arctic regions, we already calculated elevation changes for the Russian Arctic archipelagos from TanDEM-X acquisitions (2000-2017). Currently, we are preparing similar TanDEM-X DEM differences for Arctic glaciers outside the Greenland ice sheet (Svalbard, Iceland, Alaska, Canadian Arctic, Scandinavia and North Asia). In contrast to the wide and smooth areas of the East and West Antarctic ice sheets, the steep topography of the Antarctic Peninsula strongly limits the application of altimeter data for accurately quantifying glacier mass changes. Therefore, we computed glacier mass changes along the Antarctic Peninsula by means of TanDEM-X data.</p><p>Additionally, measurements of the IceSAT2 laser altimeter will be integrated in the analysis to improve the estimation of radar signal penetration into snow and firn and thereby reduce the elevation change and mass balance uncertainties.</p>

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