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 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).

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 digital elevation model of the Antarctic ice sheet derived from ERS-1 altimeter data and comparison with terrestrial measurements

1994 ◽  
Vol 20 ◽  
pp. 48-54
Author(s):  
Jonathan L. Bamber
Keyword(s):  
Standard Deviation ◽  
Digital Elevation Model ◽  
Satellite Altimetry ◽  
Ice Sheet ◽  
Altimeter Data ◽  
Geopotential Model ◽  
Antarctic Ice Sheet ◽  
Digital Elevation ◽  
Elevation Model ◽  
The Antarctic

The launch of ERS-1 provides coverage, by satellite altimetry, of 80% of the Antarctic ice sheet, allowing topographic mapping of areas which previously had a dearth of accurate elevation data. Four 35 d repeat cycles of fastdelivery altimeter data were used in this study, comprising a total of approximately 1000000 height estimates. About 40% of these were rejected during a careful filtering procedure designed to remove erroneous values caused by poor tracking or complete loss of the returned echo. The OSU-91A geopotential model was used to convert ellipsoidal elevations to geoidal values. Corrections for surface slope were applied and a Digital Elevation Model (DEM) was produced with a grid spacing of 20km.The precision of the data was assessed from an analysis of crossing points of ascending and descending tracks. For 43864 cross-overs, the standard deviation was 6.8m. Regional biases associated with geoid, orbit and topography-induced errors reduce the accuracy of the height measurements. This was assessed by a comparison with ground-survey data. The DEM was compared with a 700km levelling survey, with an accuracy ranging from 1 to 5m, from the Lambert Glacier basin region (≈73° S, 55° E). The mean difference was found to be-1.6m with a standard deviation of 14m. A similar result was obtained for a 600km traverse line in Wilkes Land (75° S,≈1l0° E).The DEM was then compared with a digitized version of the Scott Polar Research Institute (SPRI) Antarctic folio map. This map was derived from orthometric measurements of surface elevation, primarily from pressure altimetry. Differences in excess of 300 m were observed between the two data sets. Only 37% of the region covered showed agreement to better than 50m, and a significant proportion ofthis was composed of the Ross and Filchner-Ronne Ice Shelves. The largest discrepancies occurred in marginal areas where there is poor coverage by both satellite altimetry and terrestrial data. Inland, significant differences were also found.

scholarly journals A digital elevation model of the Antarctic ice sheet derived from ERS-1 altimeter data and comparison with terrestrial measurements

1994 ◽  
Vol 20 ◽  
pp. 48-54 ◽  
Author(s):  
Jonathan L. Bamber
Keyword(s):  
Standard Deviation ◽  
Digital Elevation Model ◽  
Satellite Altimetry ◽  
Ice Sheet ◽  
Altimeter Data ◽  
Geopotential Model ◽  
Antarctic Ice Sheet ◽  
Digital Elevation ◽  
Elevation Model ◽  
The Antarctic

The launch of ERS-1 provides coverage, by satellite altimetry, of 80% of the Antarctic ice sheet, allowing topographic mapping of areas which previously had a dearth of accurate elevation data. Four 35 d repeat cycles of fastdelivery altimeter data were used in this study, comprising a total of approximately 1000000 height estimates. About 40% of these were rejected during a careful filtering procedure designed to remove erroneous values caused by poor tracking or complete loss of the returned echo. The OSU-91A geopotential model was used to convert ellipsoidal elevations to geoidal values. Corrections for surface slope were applied and a Digital Elevation Model (DEM) was produced with a grid spacing of 20km.The precision of the data was assessed from an analysis of crossing points of ascending and descending tracks. For 43864 cross-overs, the standard deviation was 6.8m. Regional biases associated with geoid, orbit and topography-induced errors reduce the accuracy of the height measurements. This was assessed by a comparison with ground-survey data. The DEM was compared with a 700km levelling survey, with an accuracy ranging from 1 to 5m, from the Lambert Glacier basin region (≈73° S, 55° E). The mean difference was found to be-1.6m with a standard deviation of 14m. A similar result was obtained for a 600km traverse line in Wilkes Land (75° S,≈1l0° E).The DEM was then compared with a digitized version of the Scott Polar Research Institute (SPRI) Antarctic folio map. This map was derived from orthometric measurements of surface elevation, primarily from pressure altimetry. Differences in excess of 300 m were observed between the two data sets. Only 37% of the region covered showed agreement to better than 50m, and a significant proportion ofthis was composed of the Ross and Filchner-Ronne Ice Shelves. The largest discrepancies occurred in marginal areas where there is poor coverage by both satellite altimetry and terrestrial data. Inland, significant differences were also found.

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.

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