scholarly journals Interferometric radar observations of Glaciares Europa and Penguin, Hielo Patagónico Sur, Chile

1999 ◽  
Vol 45 (150) ◽  
pp. 325-337 ◽  
Author(s):  
Richard R. Forster ◽  
Eric Rignot ◽  
Bryan L. Isacks ◽  
Kenneth C. Jezek
Keyword(s):  
Space Shuttle ◽  
Phase Coherence ◽  
Surface Velocity ◽  
Interferometric Synthetic Aperture Radar ◽  
Low Coherence ◽  
Ice Surface ◽  
Digital Elevation ◽  
Ice Velocity ◽  
Elevation Model ◽  
High Degree

AbstractRepeat-pass L-band interferometric synthetic aperture radar (InSAR) data for part of Hielo Patagónico Sur, Chile, were collected by the space-shuttle-based Spaceborne Imaging Radar C (SIR-C) over a 4 day span in October 1994. Three co-registered complex SAR images are used to generate phase-coherence maps, a digital elevation model (DEM) and an ice-velocity map. The phase-coherence maps indicate low coherence in the 5–15 km approaching the termini due to large displacements, ice deformation and melting. However, the coherence is high over nearly all of the remaining imaged icefield. Ice-velocity precision is greater than 2 cm d−1, while the DEM is good to about 25 m. A flow divide between two of the glaciers is mapped by locating a narrow band of near-zero ice velocity. Horizontal ice-surface velocity profiles calculated along flowlines show there is a high degree of spatial variability reaching a peak value of 5.5 m d−1located 3.5 km from the terminus of Glaciar Europa. Longitudinal strain rates along the center lines calculated from these velocities at the locations of the initiation of crevassing are used to compute the tensile strength of ice (169–224 kPa).

scholarly journals Interferometric radar observations of Glaciares Europa and Penguin, Hielo Patagónico Sur, Chile

1999 ◽  
Vol 45 (150) ◽  
pp. 325-337 ◽  
Author(s):  
Richard R. Forster ◽  
Eric Rignot ◽  
Bryan L. Isacks ◽  
Kenneth C. Jezek
Keyword(s):  
Space Shuttle ◽  
Phase Coherence ◽  
Surface Velocity ◽  
Interferometric Synthetic Aperture Radar ◽  
Low Coherence ◽  
Ice Surface ◽  
Digital Elevation ◽  
Ice Velocity ◽  
Elevation Model ◽  
High Degree

AbstractRepeat-pass L-band interferometric synthetic aperture radar (InSAR) data for part of Hielo Patagónico Sur, Chile, were collected by the space-shuttle-based Spaceborne Imaging Radar C (SIR-C) over a 4 day span in October 1994. Three co-registered complex SAR images are used to generate phase-coherence maps, a digital elevation model (DEM) and an ice-velocity map. The phase-coherence maps indicate low coherence in the 5–15 km approaching the termini due to large displacements, ice deformation and melting. However, the coherence is high over nearly all of the remaining imaged icefield. Ice-velocity precision is greater than 2 cm d−1, while the DEM is good to about 25 m. A flow divide between two of the glaciers is mapped by locating a narrow band of near-zero ice velocity. Horizontal ice-surface velocity profiles calculated along flowlines show there is a high degree of spatial variability reaching a peak value of 5.5 m d−1 located 3.5 km from the terminus of Glaciar Europa. Longitudinal strain rates along the center lines calculated from these velocities at the locations of the initiation of crevassing are used to compute the tensile strength of ice (169–224 kPa).

scholarly journals Decadal GPS-derived ice surface velocity along the transect from Zhongshan Station to and around Dome Argus, East Antarctica, 2005–16

2018 ◽  
Vol 59 (76pt1) ◽  
pp. 1-9 ◽  
Author(s):  
Yang Yuande ◽  
Ke Hao ◽  
Wang Zemin ◽  
Li Fei ◽  
Ding Minghu ◽  
...  
Keyword(s):  
High Resolution ◽  
Ground Truth ◽  
East Antarctica ◽  
Surface Velocity ◽  
Interferometric Synthetic Aperture Radar ◽  
Gps Measurements ◽  
Zhongshan Station ◽  
Ice Surface ◽  
Ice Velocity ◽  
Ice Sheet Dynamics

ABSTRACTUsing repeat GPS measurements during 2005–16, we calculated and updated two-dimensional high-resolution decadal ice surface velocity estimates along the traverse route from Zhongshan Station to and around Dome Argus, East Antarctica. Along the 71 sites of the transect, the magnitudes of ice velocity increased from near 0 in Dome Argus to 1, 10 and ~100 m a−1 at the sites DT416, DT333 and LT980, respectively. The comparison between GPS and interferometric synthetic aperture radar (InSAR) derived results agree well when the magnitude of the ice surface velocities is faster than 5 m a−1, and disagree for slower flow velocities. A scale value 1.15 and 0.12 can be applied to InSAR derived results over this region with ice surface velocity larger and <5 m a−1, respectively. We attributed the cause of the discrepancy to the insensitivity of InSAR to the magnitude of low ice surface velocities, thus confirming the importance of GPS fieldwork-based ground truth high-resolution ice velocity estimates to constrain ice-sheet dynamics.

scholarly journals Dynamics of Dalk Glacier in East Antarctica Derived from Multisource Satellite Observations Since 2000

2020 ◽  
Vol 12 (11) ◽  
pp. 1809
Author(s):  
Yiming Chen ◽  
Chunxia Zhou ◽  
Songtao Ai ◽  
Qi Liang ◽  
Lei Zheng ◽  
...  
Keyword(s):  
East Antarctica ◽  
Surface Velocity ◽  
Cyclic Behavior ◽  
Glacier Terminus ◽  
Digital Elevation ◽  
Ice Velocity ◽  
Velocity Changes ◽  
Elevation Model ◽  
Surface Ice

Monitoring variability in outlet glaciers can improve the understanding of feedbacks associated with calving, ocean thermal forcing, and climate change. In this study, we present a remote-sensing investigation of Dalk Glacier in East Antarctica to analyze its dynamic changes. Terminus positions and surface ice velocities were estimated from Landsat and Sentinel-1 data, and the high-precision Worldview digital elevation model (DEM) was generated to determine the location of the potential ice rumple. We detected the cyclic behavior of glacier terminus changes and similar periodic increases in surface velocity since 2000. The terminus retreated in 2006, 2009, 2010, and 2016 and advanced in other years. The surface velocity of Dalk Glacier has a 5-year cycle with interannual speed-ups in 2007, 2012, and 2017. Our observations show the relationship between velocity changes and terminus variations, as well as the driving role of the ice rumple. Ice velocity often increases after calving events and continuous retreats. The loss of buttressing provided by an ice rumple may be a primary factor for increases in ice velocity. Given the restriction of the ice rumple, the surface velocity remains relatively stable when the glacier advances. The calving events may be linked to the unstable terminus caused by the ice rumple.

scholarly journals Ice velocity measurements of Langjökull, Iceland, from interferometric synthetic aperture radar (InSAR)

2009 ◽  
Vol 55 (193) ◽  
pp. 834-838 ◽  
Author(s):  
Steven Palmer ◽  
Andrew Shepherd ◽  
Helgi Björnsson ◽  
Finnur Pálsson
Keyword(s):  
Interferometric Synthetic Aperture Radar ◽  
Velocity Measurements ◽  
Gps Measurements ◽  
Ice Flow ◽  
Ice Cap ◽  
Gps Survey ◽  
Ice Surface ◽  
Ice Velocity ◽  
Elevation Model ◽  
Good Agreement

AbstractWe have computed the velocity of Langjökull ice cap (LIC), Iceland, using InSAR data acquired by the European Remote-sensing Satellite in 1994 and an ice-surface elevation model derived from a GPS survey conducted in 1997. The velocity map covers 68% of the 925 km2 of LIC. Eight principal outlet glaciers were identified, along which ice velocities increased from zero at the ice divide to a maximum of 75 m a−1. When the InSAR velocity dataset is compared with surface GPS measurements of ice flow determined in summer 2001, there is generally good agreement, suggesting interannual and seasonal stability for much of the ice cap during this period. However, non-zero ice velocities at the termini of four of the eight glaciers surveyed suggest that these glaciers were advancing in 1994. Comparison of our GPS and InSAR velocities suggests that Sudurjökull experienced elevated velocity in late February 1994, which, when other studies are considered, appears to be consistent with a glacier surge.

scholarly journals The propagation of a surge front on Bering Glacier, Alaska, 2001–2011

2013 ◽  
Vol 54 (63) ◽  
pp. 221-228 ◽  
Author(s):  
James Turrin ◽  
Richard R. Forster ◽  
Chris Larsen ◽  
Jeanne Sauber
Keyword(s):  
Feature Tracking ◽  
Average Rate ◽  
Surface Velocity ◽  
Ablation Zone ◽  
Ice Surface ◽  
Glacier Terminus ◽  
Bering Glacier ◽  
Landsat 7 ◽  
Ice Velocity ◽  
Recent Activity

AbstractBering Glacier, Alaska, USA, has a ∼20 year surge cycle, with its most recent surge reaching the terminus in 2011. To study this most recent activity a time series of ice velocity maps was produced by applying optical feature-tracking methods to Landsat-7 ETM+ imagery spanning 2001-11. The velocity maps show a yearly increase in ice surface velocity associated with the down-glacier movement of a surge front. In 2008/09 the maximum ice surface velocity was 1.5 ±0.017 km a-1 in the mid-ablation zone, which decreased to 1.2 ±0.015 km a-1 in 2009/10 in the lower ablation zone, and then increased to nearly 4.4 ± 0.03 km a-1 in summer 2011 when the surge front reached the glacier terminus. The surge front propagated down-glacier as a kinematic wave at an average rate of 4.4 ±2.0 km a-1 between September 2002 and April 2009, then accelerated to 13.9 ± 2.0 km a-1 as it entered the piedmont lobe between April 2009 and September 2010. The wave seems to have initiated near the confluence of Bering Glacier and Bagley Ice Valley as early as 2001, and the surge was triggered in 2008 further down-glacier in the mid-ablation zone after the wave passed an ice reservoir area.

scholarly journals A new Greenland digital elevation model derived from ICESat-2

2021 ◽  
Author(s):  
Yubin Fan ◽  
Chang-Qing Ke ◽  
Xiaoyi Shen
Keyword(s):  
High Accuracy ◽  
Great Accuracy ◽  
Model Fit ◽  
Kriging Interpolation ◽  
Additional Time ◽  
Spatiotemporal Model ◽  
Digital Elevation ◽  
Ice Velocity ◽  
Image Pairs ◽  
Elevation Model

Abstract. Greenland digital elevation models (DEMs) are indispensable to fieldwork, ice velocity calculations and mass change estimations. Previous DEMs provided Greenland elevation information for different periods, but long temporal coverage introduced additional time uncertainty to scientific research. To provide a high-resolution DEM with a definite time, approximately 5.8 × 108 ICESat-2 observations from November 2018 to November 2019 were used to generate a new DEM for both the ice sheet and glaciers in peripheral Greenland. A spatiotemporal model fit process was first performed at 500 m resolution. To improve ICESat-2 data utilization, DEMs with 1 km and 2 km resolution across all of Greenland and an additional 5 km resolution in southernmost Greenland were used to fill the DEM gaps. Kriging interpolation was used to fill the remaining 2 % of void grids that were insufficiently observed by ICESat-2 measurements. IceBridge mission data acquired by the Airborne Topographic Mapper (ATM) Lidar system were used to evaluate the accuracy of the newly generated ICESat-2 DEM. Overall, the ICESat-2 DEM had a median difference of −0.48 m for all of Greenland, which agreed well with the IceBridge data, and the performance in the calculated and interpolated grids was similar. Better accuracy could be observed in the northern basins due to the larger proportion of calculated grids with 500 m resolution. The ICESat-2 DEM showed significant improvements in accuracy compared with other altimeter-derived DEMs. Compared to the DEM generated by image pairs, the accuracy was also significantly higher than those of the 1 km ArcticDEM and TanDEM. Similar performance between the ICESat-2 DEM and 500 m ArcticDEM indicated the high accuracy and reliability of the ICESat-2 DEM. Moreover, the ICESat-2 DEM performed better on northern aspects than the 500 m ArcticDEM. Overall, the ICESat-2 DEM showed great accuracy stability under various topographic conditions, hence providing a time-accurate DEM with high accuracy that will be helpful to study elevation and mass balance changes in Greenland. The Greenland DEM and its uncertainty are available at (https://data.tpdc.ac.cn/en/disallow/07497631-047548b5-ba53-c17f9076c72f/, Fan et al, 2021).

scholarly journals Simulation of Three-Dimensional of coastal erosion using differential interferometric synthetic aperture radar

2013 ◽  
Vol 16 (1) ◽  
pp. 80-86
Keyword(s):  
Synthetic Aperture Radar ◽  
Three Dimensional ◽  
Shoreline Change ◽  
Synthetic Aperture ◽  
Interferometric Synthetic Aperture Radar ◽  
Envisat Asar ◽  
Digital Elevation ◽  
Elevation Model ◽  
Dimensional Object ◽  
Aperture Radar

<p>This study aims at modelling three-dimensional shoreline change rates using differential interferometric synthetic aperture radar (DInSAR) techinuqe. Neverthless, decorrelation plays significant role to control the accuracy of three dimensional object reconstruction using DInSAR. To solve this problem, multichannel MAP height estimator algorithm is implemented with in ENVISAT ASAR data. Therefore, the proposed method has been applied to coastaline of Johor, Malaysia. The study shows the critical erosion of -3.5 m y-1 with accuracy (RMSE) of &plusmn;0.05 m. In addition, the volume rate of shoreline changes of -2343.42 m3 y-1 corresponds to the lowest digital elevation model (DEM) of 7.4 m. It can be said that accurate rate of shoreline change can be achieved with root mean square error (RMSE) of &plusmn;0.05 m using multichannel MAP height estimator algorithm.</p>

scholarly journals Weighted Visibility Classification and Seating Plan for the Aitken University Centre

2014 ◽  
Vol XL-2 ◽  
pp. 227-234
Author(s):  
T. Allison ◽  
D. Fraser ◽  
E. Stefanakis
Keyword(s):  
Web Application ◽  
Web Applications ◽  
Ice Surface ◽  
Price Levels ◽  
Digital Elevation ◽  
Information Products ◽  
Interactive Map ◽  
Elevation Model ◽  
The University

This paper describes the requirements for a weighted visibility classification of seats in the University of New Brunswick’s (UNB) Aitken University Centre (AUC). Price levels for seats are typically set for sections of seats based on promoter preferences. In a visibility classification, the digital elevation model (DEM) is created for the AUC and includes possible view obstructions. The view obstructions taken into account for this design were the penalty boxes, player bencher, and the rink boards. There were no other major obstructions in the AUC. The visibility calculations compute the number of visible pixels of the rink surface for each seat. It is expected that seats with a higher number of visible pixels will also have better visibility. The number of viewable pixels is weighted by distance to the center of ice surface to account for the preference of seats that are closer to the rink surface. This paper outlines the collection of data, weighted visibility classification method, and the development of information products. There are two main objectives of this weighted visibility classification and seating plan: (a) to demonstrate that a weighted visibility classification is a viable method to classify seats, and that this methodology could be used to set price levels for a venue and (b) create online web applications to suit the functionality for users and venue administrators. The user web application allows the user to pan, zoom and perform limited searches in the interactive map.

scholarly journals ERS SAR feature-tracking measurement of outlet glacier velocities on a regional scale in East Greenland

2003 ◽  
Vol 36 ◽  
pp. 129-134 ◽  
Author(s):  
Adrian Luckman ◽  
Tavi Murray ◽  
Hester Jiskoot ◽  
Hamish Pritchard ◽  
Tazio Strozzi
Keyword(s):  
Feature Tracking ◽  
Regional Scale ◽  
Surface Velocity ◽  
Ice Flow ◽  
Outlet Glacier ◽  
East Greenland ◽  
Ice Surface ◽  
Fast Ice ◽  
Regional Basis ◽  
Ice Velocity

AbstractFeature tracking, or patch intensity cross-correlation, is used to derive two-dimensional ice-surface velocity fields from 1day and 35 day repeat-pass European Remote-sensing Satellite (ERS) synthetic aperture radar (SAR) data covering a 500 km by 500 km area of central East Greenland. Over regions of fast ice flow, 35 day tracking yields only a slightly lower density of velocity measurements than 1day tracking, and both are broadly in agreement about the spatial pattern of ice velocity except at the glacier termini where tidal effects may dominate. This study suggests that SAR feature tracking may be used to routinely monitor ice-discharge velocities on a regional basis and thereby inform studies of regional mass balance.

scholarly journals Glacier mass balance over the central Nyainqentanglha Range during recent decades derived from remote-sensing data

2019 ◽  
Vol 65 (251) ◽  
pp. 422-439 ◽  
Author(s):  
KUNPENG WU ◽  
SHIYIN LIU ◽  
ZONGLI JIANG ◽  
JUNLI XU ◽  
JUNFENG WEI
Keyword(s):  
Mass Balance ◽  
Remote Sensing Data ◽  
Shuttle Radar Topography Mission ◽  
Topographic Maps ◽  
Glacier Mass Balance ◽  
Glacier Area ◽  
Ice Surface ◽  
Digital Elevation ◽  
Elevation Changes ◽  
Elevation Model

ABSTRACTTo obtain information on changes in glacier mass balance in the central Nyainqentanglha Range, a comprehensive study was carried out based on digital-elevation models derived from the 1968 topographic maps, the Shuttle Radar Topography Mission DEM (2000) and TerraSAR-X/TanDEM-X (2013). Glacier area changes between 1968 and 2016 were derived from topographic maps and Landsat OLI images. This showed the area contained 715 glaciers, with an area of 1713.42 ± 51.82 km2, in 2016. Ice cover has been shrinking by 0.68 ± 0.05% a−1 since 1968. The glacier area covered by debris accounted for 11.9% of the total and decreased in the SE–NW directions. Using digital elevation model differencing and differential synthetic aperture radar interferometry, a significant mass loss of 0.46 ± 0.10 m w.e. a−1 has been recorded since 1968; mass losses accelerated from 0.42 ± 0.20 m w.e. a−1 to 0.60 ± 0.20 m w.e. a−1 between 1968–2000 and 2000–2013, with thinning noticeably greater on the debris-covered ice than the clean ice. Surface-elevation changes can be influenced by ice cliffs, as well as debris cover and land- or lake-terminating glaciers. Changes showed spatial and temporal heterogeneity and a substantial correlation with climate warming and decreased precipitation.

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