scholarly journals Low-frequency radar sounding of ice in East Antarctica and southern Greenland

2014 ◽  
Vol 55 (67) ◽  
pp. 138-146 ◽  
Author(s):  
J. Mouginot ◽  
E. Rignot ◽  
Y. Gim ◽  
D. Kirchner ◽  
E. Le Meur
Keyword(s):  
Low Frequency ◽  
Radar Data ◽  
East Antarctica ◽  
Radar Signal ◽  
Airborne Radar ◽  
Ice Thickness ◽  
Decameter Wavelength ◽  
Radar Sounder ◽  
Thickness Measurements ◽  
Southwest Greenland

AbstractWe discuss a decameter-wavelength airborne radar sounder, the Warm Ice Sounding Explorer (WISE), that provides ice thickness in areas where radar signal penetration at higher frequencies is expected to be limited. Here we report results for three campaigns conducted in Greenland (2008, 2009, 2010) and two in Antarctica (2009, 2010). Comparisons with higher-frequency radar data indicate an accuracy of ±55 m for ice-thickness measurements in Greenland and ±25 m in Antarctica. We also estimate ice thickness of the Qassimiut lobe in southwest Greenland, where few ice-thickness measurements have been made, demonstrating that WISE penetrates in strongly scattering environments.

scholarly journals Comparison of Electromagnetic and Seismic-Gravity Ice Thickness Measurements in East Antarctica

1975 ◽  
Vol 15 (73) ◽  
pp. 137-150 ◽  
Author(s):  
David J. Drewry
Keyword(s):  
Seismic Reflection ◽  
East Antarctica ◽  
Ice Thickness ◽  
South Pole ◽  
Victoria Land ◽  
Radio Echo Sounding ◽  
Mean Differences ◽  
Thickness Measurements ◽  
Better Than ◽  
Echo Sounding

AbstractThe errors involved in ice thickness determinations in Antarctica by seismic reflection shooting, gravity observations and radio-echo sounding are briefly discussed. Relative accuracies of 3%, 7-10% and 1.5% have been suggested. Double checks of ice depths from radar sounding in east Antarctica indicate an internal consistency of measurement for this technique of <1%. Comparison of carefully executed seismic shooting and routine radio-echo sounding results against absolute ice thickness values from two deep core drilling sites show no significant differences between these two remote methods (i.e. both are better than 1.5%).Over 60 comparisons are examined between radar ice thicknesses and over-snow measurements obtained on eight independent traverses in east Antarctica. Three traverses exhibit consistently unacceptable results-U.S. Victoria Land Traverse II (southern leg), Commonwealth Transanlarctic Expedition and the U.S.S.R. Vostok to South Pole Traverse—which probably result from misinterpretation of “noisy” seismograms. The remaining comparisons indicate mean differences, including some navigational uncertainty, of ≈3%, <8% and 5% between radio-echo and (1) seismic, (2) gravity, and (3) gravity tied to seismic determinations, respectively.

scholarly journals Airborne radar survey above Vostok region, east-central Antarctica: ice thickness and Lake Vostok geometry

2002 ◽  
Vol 48 (160) ◽  
pp. 62-69 ◽  
Author(s):  
Ignazio E. Tabacco ◽  
Cesido Bianchi ◽  
Achille Zirizzotti ◽  
Enrico Zuccheretti ◽  
Alessandro Forieri ◽  
...  
Keyword(s):  
Major Axis ◽  
Radar Data ◽  
Surface Elevation ◽  
Airborne Radar ◽  
Ice Thickness ◽  
Maximum Width ◽  
East Central ◽  
Absolute Value ◽  
Lake Vostok ◽  
Ice Surface

AbstractDuring the 1999–2000 Italian Expedition, an airborne radar survey was performed along 12 transects across Lake Vostok, Antarctica, and its western and eastern margins. Ice thickness, subglacial elevation and the precise location of lake boundaries were determined. Radar data confirm the geometry derived from previous surveys, but with some slight differences. We measured a length of up to 260 km, a maximum width of 81 km and an area of roughly 14 000 km2. Along the major axis, from north to south, the ice thickness varies from 3800 to 4250 m, with a decreasing gradient. From west to east the ice thickness is fairly constant, except for two narrow strips located on the western and eastern margins, where it increases with high thickening rate. Over the lake the surface elevation increases from 3476 m a.s.l. (south) to 3525 (north), with a decreasing gradient, while the lake surface elevation decreases from −315 to −750 m a.s.l., with a decreasing gradient (absolute value). The ice-surface and lake-ceiling slopes suggest that the lake is in a state of hydrostatic equilibrium.

Wavelet Based Processing of Airborne Radar Data from East Antarctica

2002 ◽  
Author(s):  
M. Pipan ◽  
M. de Vecchi ◽  
E. Forte ◽  
I. Tabacco
Keyword(s):  
Radar Data ◽  
East Antarctica ◽  
Airborne Radar

scholarly journals A low-frequency ice-penetrating radar system adapted for use from an airplane: test results from Bering and Malaspina Glaciers, Alaska, USA

2009 ◽  
Vol 50 (51) ◽  
pp. 93-97 ◽  
Author(s):  
Howard Conway ◽  
Ben Smith ◽  
Pavan Vaswani ◽  
Kenichi Matsuoka ◽  
Eric Rignot ◽  
...  
Keyword(s):  
Low Frequency ◽  
Radar System ◽  
Ice Thickness ◽  
Radio Waves ◽  
Low Frequencies ◽  
Throat Region ◽  
High Attenuation ◽  
Glacier System ◽  
Dielectric Absorption ◽  
Thickness Measurements

AbstractIce-thickness measurements are needed to calculate fluxes through fast-flowing outlet glaciers in Greenland, Alaska, Patagonia and Antarctica. However, relatively high attenuation of radio waves by dielectric absorption and volume scattering from englacial water hampers detection of the bed through warm deep ice. In the past we have had success measuring ice thickness of temperate glaciers using a ground-based monopulse radar system operating at low frequencies (2 MHz). Here we adapt the same system to operate from an airplane. Test flights over Bering Glacier, Alaska, USA, detected the bed through ice up to 1250m thick. Flights across the Seward–Malaspina Glacier system, Alaska, resolved the ice thickness of Malaspina Glacier, but strong hyperbolic-shaped returns obscured the bed echo through the Seward throat. It is likely that this clutter in the signal was caused by off-nadir returns from chaotic surface crevasses that are ubiquitous in the throat region.

scholarly journals Implications of surface flooding on airborne estimates of snow depth on sea ice

2021 ◽  
Vol 15 (6) ◽  
pp. 2819-2833
Author(s):  
Anja Rösel ◽  
Sinead Louise Farrell ◽  
Vishnu Nandan ◽  
Jaqueline Richter-Menge ◽  
Gunnar Spreen ◽  
...  
Keyword(s):  
Sea Ice ◽  
Validation Studies ◽  
Snow Depth ◽  
The Arctic ◽  
Airborne Radar ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Thickness Measurements ◽  
Snow And Ice

Abstract. Snow depth observations from airborne snow radars, such as the NASA's Operation IceBridge (OIB) mission, have recently been used in altimeter-derived sea ice thickness estimates, as well as for model parameterization. A number of validation studies comparing airborne and in situ snow depth measurements have been conducted in the western Arctic Ocean, demonstrating the utility of the airborne data. However, there have been no validation studies in the Atlantic sector of the Arctic. Recent observations in this region suggest a significant and predominant shift towards a snow-ice regime caused by deep snow on thin sea ice. During the Norwegian young sea Ice, Climate and Ecosystems (ICE) expedition (N-ICE2015) in the area north of Svalbard, a validation study was conducted on 19 March 2015. This study collected ground truth data during an OIB overflight. Snow and ice thickness measurements were obtained across a two-dimensional (2-D) 400 m × 60 m grid. Additional snow and ice thickness measurements collected in situ from adjacent ice floes helped to place the measurements obtained at the gridded survey field site into a more regional context. Widespread negative freeboards and flooding of the snowpack were observed during the N-ICE2015 expedition due to the general situation of thick snow on relatively thin sea ice. These conditions caused brine wicking into and saturation of the basal snow layers. This causes the airborne radar signal to undergo more diffuse scattering, resulting in the location of the radar main scattering horizon being detected well above the snow–ice interface. This leads to a subsequent underestimation of snow depth; if only radar-based information is used, the average airborne snow depth was 0.16 m thinner than that measured in situ at the 2-D survey field. Regional data within 10 km of the 2-D survey field suggested however a smaller deviation between average airborne and in situ snow depth, a 0.06 m underestimate in snow depth by the airborne radar, which is close to the resolution limit of the OIB snow radar system. Our results also show a broad snow depth distribution, indicating a large spatial variability in snow across the region. Differences between the airborne snow radar and in situ measurements fell within the standard deviation of the in situ data (0.15–0.18 m). Our results suggest that seawater flooding of the snow–ice interface leads to underestimations of snow depth or overestimations of sea ice freeboard measured from radar altimetry, in turn impacting the accuracy of sea ice thickness estimates.

scholarly journals Age stratigraphy in the East Antarctic Ice Sheet inferred from radio echo sounding horizons

2018 ◽  
Author(s):  
Anna Winter ◽  
Daniel Steinhage ◽  
Timothy T. Creyts ◽  
Thomas Kleiner ◽  
Olaf Eisen
Keyword(s):  
Ice Sheet ◽  
Ice Cores ◽  
Radar Data ◽  
East Antarctica ◽  
Airborne Radar ◽  
Antarctic Ice Sheet ◽  
Radio Echo Sounding ◽  
Flow Features ◽  
Dronning Maud Land ◽  
East Antarctic Ice Sheet

Abstract. The East Antarctic Ice Sheet contains a wealth of information that can be extracted from its internal architecture such as distribution of age, past flow features and surface and basal properties. Airborne radar surveys can sample this stratigraphic archive across broad areas. Here, we identify and trace key horizons across several radar surveys to obtain the stratigraphic information. We transfer the age-depth scales from ice cores to intersecting radar data. We then propagate these age scales across the ice sheet using the high fidelity continuity of the radar horizons. In Dronning Maud Land, including Dome Fuji, we mapped isochrones with ages of 38 ka and 74 ka. In the central region of East Antarctica around Dome Concordia, Vostok, and Dome Argus, we use isochrone ages of 38 ka, 48 ka, 90 ka, and 161 ka. Taking together both regions, we provide isochrone depths traced along a combined profile length of more than 40,000 km and discuss uncertainties of the obtained stratigraphy, as well as factors important to consider for further expansion. This dataset the most extensive distribution of internal horizons in East Antarctica to date. The isochrone depths are available on PANGAEA: https://doi.pangaea.de/10.1594/PANGAEA.895528.

scholarly journals Airborne-radar studies: Ice Streams A, B and C, West Antarctica

1993 ◽  
Vol 39 (133) ◽  
pp. 495-506 ◽  
Author(s):  
R. Retzlaff ◽  
N. Lord ◽  
C.R. Bentley
Keyword(s):  
Bottom Topography ◽  
Radar Data ◽  
Temporal Variations ◽  
Surface Elevation ◽  
Airborne Radar ◽  
Ice Thickness ◽  
Ice Streams ◽  
Clear Cut ◽  
Ice Stream ◽  
Ice Stream B

AbstractDigital airborne-radar data were collected during the 1988–89 Antarctic field season in six gridded blocks covering the upstream parts of Ice Streams A, Β and C. An automated processing procedure was developed for picking onset times, converting travel times, interpolating missing data, converting pressure-transducer readings, correcting navigational drift, performing cross-over analysis and zeroing remanent cross-over errors. Cross-over analysis was used to remove the effects of temporal variations in atmospheric pressure and to estimate errors. Interpolation between flight lines was carried out using the Kriging method. Surface elevation was referred to the Rapp Set A geoid by tying the gridded surface to satellite-surveyed ground stations, using a planar-model fit.Maps of surface elevation, ice thickness and bottom topography with standard-error estimates of 4–9 m for surface elevation and 30–60 m for ice thickness and bottom topography were produced. These maps show that the locations of the ice streams are not clearly reflected in either the surface or basal topography, so are presumably controled by basal or internal conditions, that there is no clearly demarcated transition zone between sheet flow and streaming flow, that there is no clear cut evidence for the capture of the catchment of Ice Stream C by Ice Stream B, but that Ice Stream Β does drain virtually the entire region between the lateral boundaries of Ice Streams A and C.

scholarly journals Implications of surface flooding on airborne thickness measurements of snow on sea ice

2020 ◽  
Author(s):  
Anja Rösel ◽  
Sinead Louise Farrell ◽  
Vishnu Nandan ◽  
Jaqueline Richter-Menge ◽  
Gunnar Spreen ◽  
...  
Keyword(s):  
Sea Ice ◽  
Validation Studies ◽  
The Arctic ◽  
Airborne Radar ◽  
Ice Thickness ◽  
Sea Ice Thickness ◽  
Thickness Measurements ◽  
Snow Thickness ◽  
Snow And Ice

Abstract. Snow thickness observations from airborne snow radars, such as the NASA’s Operation IceBridge (OIB) mission, have recently been used in altimeter-derived sea ice thickness estimates, as well as for model parameterization. A number of validation studies comparing airborne and in situ snow thickness measurements have been conducted in the western Arctic Ocean, demonstrating the utility of the airborne data. However, there have been no validation studies in the Atlantic sector of the Arctic. Recent observations in this region suggest a significant and predominant shift towards a snow-ice regime, caused by deep snow on thin sea ice. During the Norwegian young sea ICE expedition (N-ICE2015) in the area north of Svalbard, a validation study was conducted on March 19, 2015, during which ground truth data were collected during an OIB overflight. Snow and ice thickness measurements were obtained across a two dimensional (2-D) 400 m × 60 m grid. Additional snow and ice thickness measurements collected in situ from adjacent ice floes helped to place the measurements obtained at the gridded survey field site into a more regional context. Widespread negative freeboards and flooding of the snow pack were observed during the N-ICE2015 expedition, due to the general situation of thick snow on relatively thin sea ice. These conditions caused brine wicking and saturation into the basal snow layers, causing more diffuse scattering and influenced the airborne radar signal to detect the radar main scattering horizon well above the snow/sea ice interface, resulting in a subsequent underestimation of total snow thickness, if only radar-based information is used. The average airborne snow thickness was 0.16 m thinner than that measured in situ at the 2-D survey field. Regional data within 10 km of the 2-D survey field suggested however a smaller deviation between average airborne and in situ snow thickness, a 0.06 m underestimate in snow thickness by the airborne radar, which is close to the resolution limit of the OIB snow radar system. Our results also show a broad snow thickness distribution, indicating a large spatial variability in snow across the region. Differences between the airborne snow radar and in situ measurements fell within the standard deviation of the in situ data (0.15–0.18 m). Our results suggest that, with frequent flooding of the snow-ice interface in specific regions of the Arctic in the future, it may result in an underestimate of snow thickness or an overestimate of ice freeboard, measured from radar altimetry, thereby affecting the accuracy of sea ice thickness estimates.

scholarly journals Airborne radar sounder for temperate ice: initial results from Patagonia

2009 ◽  
Vol 55 (191) ◽  
pp. 507-512 ◽  
Author(s):  
Rodrigo Zamora ◽  
David Ulloa ◽  
Gonzalo Garcia ◽  
Ronald Mella ◽  
José Uribe ◽  
...  
Keyword(s):  
Low Frequency ◽  
Digital Camera ◽  
Airborne Radar ◽  
Digital Receiver ◽  
Gps Receiver ◽  
Laser Altimeter ◽  
System A ◽  
Southern Patagonia ◽  
Radar Sounder ◽  
Initial Results

AbstractWe describe the development of a low-frequency airborne radar specifically designed for the sounding of temperate ice. The system operates at a central frequency of 1 MHz and consists of an impulse transmitter with an output voltage up to 5000 V and a digital receiver with a maximum gain of 80 dB. The radar was deployed on board a CASA 212 aircraft, which also carries a laser altimeter, an inertial navigation system, a digital camera and a GPS receiver. A description of the radar system is provided, as well as preliminary results obtained at Glaciar Tyndall, Campo de Hielo Sur (Southern Patagonia Icefield), where an ice depth of 670 m was reached.

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