scholarly journals Focused synthetic aperture radar processing of ice-sounder data collected over the Greenland ice sheet

2001 ◽  
Vol 39 (10) ◽  
pp. 2109-2117 ◽  
Author(s):  
J.J. Legarsky ◽  
S.P. Gogineni ◽  
T.L. Akins
Keyword(s):  
Synthetic Aperture Radar ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Synthetic Aperture ◽  
Aperture Radar

scholarly journals Analysis of synthetic aperture radar Data collected over the southwestern Greenland ice sheet

1993 ◽  
Vol 39 (131) ◽  
pp. 119-132 ◽  
Author(s):  
K. C. Jezek ◽  
M. R. Drinkwater ◽  
J. P. Crawford ◽  
R. Bindschadler ◽  
R. Kwok
Keyword(s):  
Synthetic Aperture Radar ◽  
Large Scale ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Synthetic Aperture ◽  
Model Calculations ◽  
Synthetic Aperture Radar Data ◽  
Surface Patterns ◽  
Sar Data ◽  
Aperture Radar

AbstractAnalyses of the first aircraft multi-frequency, Polarimetric synthetic aperture radar (SAR) data acquired over the southwestern Greenland ice sheet are presented. Data were collected on 31 August 1989 by the Jet Propulsion Laboratory SAR using the NASA DC-8 aircraft. Along with curvilinear patterns associated with large-scale morphologic features such as crevasses, lakes and streams, frequency and polarization dependencies are observed in the P-, L-and C-band image products. Model calculations that include firn grain-size and volumetric water content suggest that tonal variations in and between the images are attributable to large-scale variations in the snow-and ice-surface characteristics, especially snow wetness. In particular, systematic trends in back-scatter strength observed at C-band across regions of changing snow wetness are suggestive of a capability to delineate boundaries between snow facies. Ice lenses and ice pipes are the speculated cause for similar trends in P-band back-scatter. Finally, comparison between SEASAT SAR data collected in 1978 and these airborne data collected in 1989 indicate a remarkable stability of surface patterns associated with the locations of supraglacial lake and stream systems.

scholarly journals An analysis of balance velocities over the Greenland ice sheet and comparison with synthetic aperture radar interferometry

2000 ◽  
Vol 46 (152) ◽  
pp. 67-74 ◽  
Author(s):  
J. L. Bamber ◽  
R. J. Hardy ◽  
I. Joughin
Keyword(s):  
Synthetic Aperture Radar ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ablation Rate ◽  
Sar Interferometry ◽  
Synthetic Aperture ◽  
Ice Thickness ◽  
Good Representation ◽  
Elevation Model ◽  
Aperture Radar

AbstractBalance velocities for the Greenland ice sheet have been calculated from a new digital elevation model (DEM), accumulation rates and an existing ice-thickness grid, using a fully two-dimensional finite-difference scheme. The pattern of velocities is compared with velocities derived from synthetic-aperture radar (SAR) interferometry for three different regions of the ice sheet. Differences between the two estimates of velocity highlight the respective strengths and weaknesses of the datasets and techniques used. A comparison with ten global positioning system-derived velocities indicates that the balance-velocity scheme and input datasets used here provide a remarkably good representation of the velocity distribution inland from the margins. These balance-velocity data, therefore, could help constrain numerical ice-sheet models. The balance velocities were found to be unreliable close to the ice-sheet margins due to larger errors in ice thickness, surface slope and ablation rate in this region. Comparison of the balance velocities with SAR interferometry in the region of the “Northeast Greenland Ice Stream” indicates the importance of the smoothing distance that must be applied to the DEM before calculating balance velocities. A smoothing distance of 20 times the ice thickness gave good agreement between the two measures of velocity.

Monitoring the Greenland Ice Sheet: A comparison between Sentinel-3 and CryoSat-2 radar altimeters

2020 ◽  
Author(s):  
Jennifer Maddalena ◽  
Geoffrey Dawson ◽  
Stephen Chuter ◽  
Jack Landy ◽  
Jonathan Bamber
Keyword(s):  
Synthetic Aperture Radar ◽  
Volume Change ◽  
Interpolation Method ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Synthetic Aperture ◽  
Radar Altimeter ◽  
Elevation Change ◽  
Crossover Analysis ◽  
Aperture Radar

<p>Since 1992, satellite-borne radar altimetry has been used to record surface elevation change over the Greenland ice sheet (GrIS). Until the launch of CryoSat-2 in 2010, conventional radar altimeters performed poorly over high sloping terrain with heterogenous topography. The novel synthetic aperture radar interferometric (SARIn) mode of CryoSat-2 has improved capability in these regions over the margins of the GrIS, which have been experiencing the largest mass loss. ESA’s Sentinel-3 mission is the latest radar-altimeter to be launched. The first satellite, Sentinel-3A, was launched in February 2016 followed by Sentinel-3B April 2018. The Sentinel-3 satellites are the first to use synthetic aperture radar (SAR) across the interior of the GrIS. This has improved the along-track resolution to approximately 300m compared to CryoSat-2’s Low Resolution Mode (LRM) footprint which has a diameter of ~1.65km.</p><p>Here we assess the performance of Sentinel’s SAR mode compared to the LRM mode of CryoSat-2 over the interior of the ice sheet and the SARIn mode over the margins of the GrIS, through crossover analysis and a point-to-point comparison. We then assess the implications of this comparison for monitoring elevation changes over the ice sheet and we present rates of elevation change for June 2016 - June 2019 for both radar altimeter missions. To calculate rates of volume change from elevation change we use a statistical interpolation method, universal kriging, and present volume changes per basin over Greenland before comparing volume change estimates between CryoSat-2 and Sentinel-3.</p>

scholarly journals Analysis of synthetic aperture radar Data collected over the southwestern Greenland ice sheet

1993 ◽  
Vol 39 (131) ◽  
pp. 119-132 ◽  
Author(s):  
K. C. Jezek ◽  
M. R. Drinkwater ◽  
J. P. Crawford ◽  
R. Bindschadler ◽  
R. Kwok
Keyword(s):  
Synthetic Aperture Radar ◽  
Large Scale ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Synthetic Aperture ◽  
Model Calculations ◽  
Synthetic Aperture Radar Data ◽  
Surface Patterns ◽  
Sar Data ◽  
Aperture Radar

AbstractAnalyses of the first aircraft multi-frequency, Polarimetric synthetic aperture radar (SAR) data acquired over the southwestern Greenland ice sheet are presented. Data were collected on 31 August 1989 by the Jet Propulsion Laboratory SAR using the NASA DC-8 aircraft. Along with curvilinear patterns associated with large-scale morphologic features such as crevasses, lakes and streams, frequency and polarization dependencies are observed in the P-, L-and C-band image products. Model calculations that include firn grain-size and volumetric water content suggest that tonal variations in and between the images are attributable to large-scale variations in the snow-and ice-surface characteristics, especially snow wetness. In particular, systematic trends in back-scatter strength observed at C-band across regions of changing snow wetness are suggestive of a capability to delineate boundaries between snow facies. Ice lenses and ice pipes are the speculated cause for similar trends in P-band back-scatter. Finally, comparison between SEASAT SAR data collected in 1978 and these airborne data collected in 1989 indicate a remarkable stability of surface patterns associated with the locations of supraglacial lake and stream systems.

scholarly journals Iceberg Detection using Satellite Images

2021 ◽  
Vol 9 (VII) ◽  
pp. 1896-1901
Author(s):  
Dr. Ashoka K
Keyword(s):  
Neural Networks ◽  
Synthetic Aperture Radar ◽  
Convolutional Neural Networks ◽  
Satellite Images ◽  
Ice Sheet ◽  
Synthetic Aperture ◽  
The Arctic ◽  
Ice Shelves ◽  
Ice Conditions ◽  
Aperture Radar

Chunks of ice present genuine risks for transport route and seaward establishments. Subsequently, there is a huge interest to limit them ideal and over tremendous regions. As a result of their autonomy of overcast cover and sunlight, satellite Synthetic Aperture Radar (SAR) pictures are among the favoured information hotspots for functional ice conditions and ice sheet events. The picture spatial goal for the most part utilized for chunk of ice observing changes between a couple and 100 m. Prepared SAR information are portrayed by dot clamour, which causes a grainy appearance of the pictures making the distinguishing proof of ice shelves amazingly troublesome. The techniques for satellite checking of hazardous ice developments, similar to ice shelves in the Arctic oceans address a danger to the security of route and monetary action on the Arctic rack. Along these lines, here we have thought of a thought of an application which distinguishes the Iceberg pictures utilizing satellite pictures and it is proposed by utilizing Convolutional Neural Networks (CNN) grouping.

scholarly journals Differential interferometric synthetic aperture radar for tide modelling in Antarctic ice-shelf grounding zones

2019 ◽  
Vol 13 (12) ◽  
pp. 3171-3191 ◽  
Author(s):  
Christian T. Wild ◽  
Oliver J. Marsh ◽  
Wolfgang Rack
Keyword(s):  
Synthetic Aperture Radar ◽  
Ice Sheet ◽  
Synthetic Aperture ◽  
Small Scale ◽  
Gps Data ◽  
Interferometric Synthetic Aperture Radar ◽  
Ice Shelf ◽  
Absolute Residual ◽  
The Times ◽  
Aperture Radar

Abstract. Differential interferometric synthetic aperture radar (DInSAR) is an essential tool for detecting ice-sheet motion near Antarctica's oceanic margin. These space-borne measurements have been used extensively in the past to map the location and retreat of ice-shelf grounding lines as an indicator for the onset of marine ice-sheet instability and to calculate the mass balance of ice sheets and individual catchments. The main difficulty in interpreting DInSAR is that images originate from a combination of several SAR images and do not indicate instantaneous ice deflection at the times of satellite data acquisitions. Here, we combine the sub-centimetre accuracy and spatial benefits of DInSAR with the temporal benefits of tide models to infer the spatio-temporal dynamics of ice–ocean interaction during the times of satellite overpasses. We demonstrate the potential of this synergy with TerraSAR-X data from the almost-stagnant southern McMurdo Ice Shelf (SMIS). We then validate our algorithm with GPS data from the fast-flowing Darwin Glacier, draining the Antarctic Plateau through the Transantarctic Mountains into the Ross Sea. We are able to reconstruct DInSAR-derived vertical displacements to 7 mm mean absolute residual error and generally improve traditional tide-model output by up to 39 % from 10.8 to 6.7 cm RMSE against GPS data from areas where ice is in local hydrostatic equilibrium with the ocean and by up to 74 % from 21.4 to 5.6 cm RMSE against GPS data in feature-rich coastal areas where tide models have not been applicable before. Numerical modelling then reveals Young's modulus of E=1.0±0.56 GPa and an ice viscosity of ν=10±3.65 TPa s when finite-element simulations of tidal flexure are matched to 16 d of tiltmeter data, supporting the hypothesis that strain-dependent anisotropy may significantly decrease effective viscosity compared to isotropic polycrystalline ice on large spatial scales. Applications of our method include the following: refining coarsely gridded tide models to resolve small-scale features at the spatial resolution and vertical accuracy of SAR imagery, separating elastic and viscoelastic contributions in the satellite-derived flexure measurement, and gaining information about large-scale ice heterogeneity in Antarctic ice-shelf grounding zones, the missing key to improving current ice-sheet flow models. The reconstruction of the individual components forming DInSAR images has the potential to become a standard remote-sensing method in polar tide modelling. Unlocking the algorithm's full potential to answer multi-disciplinary research questions is desired and demands collaboration within the scientific community.

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