A Digital Radio Echo-Sounding and Navigation Recording System

The Scott Polar Research Institute (SPRI) Mk IV 60 MHz radio echo-sounding (RES) system has proven itself to be a most effective and versatile tool in glaciology. During the last 15 years, it has been used from a variety of platforms, both surface and airborne, and over a range of ice thicknesses from 4000 m to 100 m. However, the photographic recording methods used during this period were felt to be increasingly outdated in the context of modern data handling procedures. Accordingly, in late 1982 the Mk IV system was modified to incorporate fast digitizing of the RES receiver output, with microcomputer-controlled magnetic-tape recording of both the radar data and navigational inputs (Drewry and Liestøl 1985). The new system will be described, along with the improvements in data processing which have resulted from its use.

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Ice-volume changes (1936–1990) and structure of Aldegondabreen, Spitsbergen

Annals of Glaciology ◽

10.3189/172756405781812646 ◽

2005 ◽

Vol 42 ◽

pp. 158-162 ◽

Cited By ~ 12

Author(s):

F.J. Navarro ◽

A.F. Glazovsky ◽

Yu.Ya. Macheret ◽

E.V. Vasilenko ◽

M.I. Corcuera ◽

...

Keyword(s):

Radar Data ◽

Ice Age ◽

Aerial Photographs ◽

Joint Analysis ◽

Topographic Map ◽

Ice Volume ◽

Radio Echo Sounding ◽

Loss Of Mass ◽

Elevation Model ◽

Echo Sounding

AbstractAldegondabreen is a small valley glacier, ending on land, located in the Grønfjorden area of Spitsbergen, Svalbard. Airborne radio-echo sounding in 1974/75, using a 440 MHz radar, revealed a polythermal two-layered structure, which has been confirmed by detailed ground-based radio-echo sounding done in 1999 using a 15 MHz monopulse radar. The 1999 radar data reveal an upper cold layer extending down to 90m depth in the southern part of the glacier, where the thickest ice (216 m) was also found. A repeated pattern of diffractions from the southern part of the glacier, at depths of 50–80 m and dipping down-glacier, has been interpreted as an englacial channel which originates in the temperate ice. From joint analysis of the 1936 topographic map, a digital elevation model constructed from 1990 aerial photographs and the subglacial topography determined from radar data, a severe loss of mass during the period 1936–90 has been estimated: a glacier tongue retreat of 930 m, a decrease in area from 8.9 to 7.6 km2, in average ice thickness from 101 to 73 m and in ice volume from 0.950 to 0.558 km3, which are equivalent to an average annual balance of –0.7 mw.e. This is comparable with the only available data of net mass balance for Aldegondabreen (–1.1 and –1.35m w.e. for the balance years 1976/77 and 2002/03) and consistent with the 0.27˚C increase in mean summer air temperature in this zone during 1936–90, as well as the warming in Spitsbergen following the end of the Little Ice Age (LIA), and the general glacier recession trend observed in this region.

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Antarctic airborne radio echo sounding, 1977–78

Polar Record ◽

10.1017/s0032247400018271 ◽

1978 ◽

Vol 19 (120) ◽

pp. 267-273 ◽

Cited By ~ 30

Author(s):

D. J. Drewry ◽

D. T. Meldrum

Keyword(s):

National Science Foundation ◽

Austral Summer ◽

Applied Physics ◽

Joint Project ◽

Johns Hopkins University ◽

The Us ◽

National Science ◽

Radio Echo Sounding ◽

Polar Research Institute ◽

Echo Sounding

During the austral summer 1977–78 the Scott Polar Research Institute (SPRI) conducted a fifth season of airborne radio echo sounding in Antarctica as part of a joint project with the US National Science Foundation Division of Polar Programs (NSF-DPP) and the Technical University of Denmark (TUD). In addition, trials were undertaken of a magnetometer installation, developed and operated, under NSF contract, by the Applied Physics Laboratory (APL) of the Johns Hopkins University, USA.

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Removal of ‘strip noise’ in radio-echo sounding data using combined wavelet and 2-D DFT filtering

Annals of Glaciology ◽

10.1017/aog.2019.4 ◽

2019 ◽

Vol 61 (81) ◽

pp. 124-134

Author(s):

Bangbing Wang ◽

Bo Sun ◽

Jiaxin Wang ◽

Jamin Greenbaum ◽

Jingxue Guo ◽

...

Keyword(s):

Wavelet Transforms ◽

Radar Data ◽

Discrete Wavelet ◽

Multi Scale ◽

Ice Surface ◽

Fourier Filtering ◽

Radio Echo Sounding ◽

Instrument Noise ◽

Echo Sounding

ABSTRACTRadio-echo sounding (RES) can be used to understand ice-sheet processes, englacial flow structures and bed properties, making it one of the most popular tools in glaciological exploration. However, RES data are often subject to ‘strip noise’, caused by internal instrument noise and interference, and/or external environmental interference, which can hamper measurement and interpretation. For example, strip noise can result in reduced power from the bed, affecting the quality of ice thickness measurements and the characterization of subglacial conditions. Here, we present a method for removing strip noise based on combined wavelet and two-dimensional (2-D) Fourier filtering. First, we implement discrete wavelet decomposition on RES data to obtain multi-scale wavelet components. Then, 2-D discrete Fourier transform (DFT) spectral analysis is performed on components containing the noise. In the Fourier domain, the 2-D DFT spectrum of strip noise keeps its linear features and can be removed with a ‘targeted masking’ operation. Finally, inverse wavelet transforms are performed on all wavelet components, including strip-removed components, to restore the data with enhanced fidelity. Model tests and field-data processing demonstrate the method removes strip noise well and, incidentally, can remove the strong first reflector from the ice surface, thus improving the general quality of radar data.

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Glaciological investigations of surging ice caps in Nordaustlandet, Svalbard, 1983

Polar Record ◽

10.1017/s0032247400005611 ◽

1985 ◽

Vol 22 (139) ◽

pp. 359-378 ◽

Cited By ~ 28

Author(s):

D. J. Drewry ◽

O. Liestøl

Keyword(s):

Digital System ◽

Svalbard Archipelago ◽

Ice Caps ◽

Ice Cap ◽

Radio Echo Sounding ◽

Polar Research Institute ◽

Echo Sounding ◽

Research Institute

AbstractDuring spring 1983 a joint British-Norwegian expedition from the Scott Polar Research Institute (SPRI) and the Norsk Polarinstitutt (NP) undertook a programme of glaciological research in the Svalbard archipelago. Work focussed on obtaining airborne radio echo sounding measurements using a newly-constructed digital system and some reconnaissance observations (temperatures, net mass budgets and ice velocities) on the ice caps of Nordaustlandet for the investigation of their surging behaviour. Valley glaciers in Spitsbergen and the ice cap on Kvitøya were also sounded from the air.

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Radio Echo-Sounding of Riiser-Larsenisen (Abstract only)

Annals of Glaciology ◽

10.3189/s0260305500003347 ◽

1982 ◽

Vol 3 ◽

pp. 355-355 ◽

Cited By ~ 2

Author(s):

Olav Orheim

Keyword(s):

Outer Part ◽

Ice Thickness ◽

Horizontal Distance ◽

Ice Shelf ◽

Ice Stream ◽

Grounding Line ◽

Radio Echo Sounding ◽

Polar Research Institute ◽

Antarctic Research ◽

Echo Sounding

The Norwegian Antarctic Research Expedition 1978–79 used the Scott Polar Research Institute Mk IV radio echo-sounding system fitted in a Bell 206B helicopter to survey 620 km of Riiser-Larsenisen and 100 km across the outer part of Stancomb-Wills Ice Stream. Observed thicknesses of Riiser-Larsenisen decrease from 700 m at the grounding line to less than 200 m at the ice front. The thickness of Bllenga ice rise varied between 200 and 450 m. The ice shelf thins towards the east, and seems there to flow obliquely to the ice front (Fig.1).Step-like change in thickness of >150 m over 500 m horizontal distance i s observed in the central part of the ice shelf. The records also demonstrate undulations in ice thickness of 600 to 700 m wavelength and 50 m amplitude, and various types of rifts and crevasses. Internal layering is recorded at 250 to 300 m depth over Blåenga and i n the ice shelf up-stream of this ice rise.Observed ice thicknesses on Stancomb-Wills Ice Stream range from 130 to 220 m, with no systematic decrease towards the ice front. The records include long sections of heavy scatter from densely spaced rifts and bottom crevasses. This ice stream attains velocities > 4 km a−1, and is much more active than Riiser-Larsenisen. This high activity has resulted in extensive fracturing of the ice shelf.

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RECONSTRUCTION OF SUBGLACIAL RELIEF FROM RADIO ECHO SOUNDING RECORDS

Geophysics ◽

10.1190/1.1440146 ◽

1970 ◽

Vol 35 (6) ◽

pp. 1099-1115 ◽

Cited By ~ 61

Author(s):

C. H. Harrison

Keyword(s):

Ice Sheet ◽

Real Space ◽

Striking Difference ◽

Ice Shelves ◽

Ice Surface ◽

Radio Echo Sounding ◽

Seismic Surveying ◽

Polar Research Institute ◽

Similar Range ◽

Echo Sounding

In 1967 a party from the Scott Polar Research Institute, Cambridge, England, carried out a radio echo sounding survey of the Antarctic ice sheet; their data have been used in the analyses discussed. The radio echo sounding apparatus, basically a pulse‐modulated radar operating at 35 Mhz, was installed in a U.S. Navy Constellation aircraft with the aerials attached to the tail, giving a fan‐shaped beam. The beam is broadest along the line of flight, causing problems of interpretation analogous with those encountered in marine echo sounding and seismic surveying. Also, bottom echoes are affected by refraction at the ice surface. Examples of hyperbolic variations of echo delay with horizontal movement may be seen at the edges of ice shelves, crevasses, or cracks at the bottom of the ice. Sometimes more complex surfaces can give roughly hyperbolic echo profiles. It is possible to distinguish specular from nonspecular reflections; we use a method of computing the position of specular reflecting points from the echo profile which allows the shape of the reflecting surface to be calculated. A computer program transforms the digitized film record into a real space profile. Errors may arise from faulty digitization, but these have been largely eliminated by checking the digitized points early in the program. Occasionally, because of their similar range and echo strength, strong side echoes may be confused with sub‐ice features. A cross‐section of Nimrod Glacier and the bottom of the ice sheet near Vostok have been plotted; in both cases there is a striking difference between the computed space profile and the echo profile.

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Radio Echo-Sounding of Riiser-Larsenisen (Abstract only)

Annals of Glaciology ◽

10.1017/s0260305500003347 ◽

1982 ◽

Vol 3 ◽

pp. 355 ◽

Cited By ~ 6

Author(s):

Olav Orheim

Keyword(s):

Outer Part ◽

Ice Thickness ◽

Horizontal Distance ◽

Ice Shelf ◽

Ice Stream ◽

Grounding Line ◽

Radio Echo Sounding ◽

Polar Research Institute ◽

Antarctic Research ◽

Echo Sounding

The Norwegian Antarctic Research Expedition 1978–79 used the Scott Polar Research Institute Mk IV radio echo-sounding system fitted in a Bell 206B helicopter to survey 620 km of Riiser-Larsenisen and 100 km across the outer part of Stancomb-Wills Ice Stream. Observed thicknesses of Riiser-Larsenisen decrease from 700 m at the grounding line to less than 200 m at the ice front. The thickness of Bllenga ice rise varied between 200 and 450 m. The ice shelf thins towards the east, and seems there to flow obliquely to the ice front (Fig.1). Step-like change in thickness of >150 m over 500 m horizontal distance i s observed in the central part of the ice shelf. The records also demonstrate undulations in ice thickness of 600 to 700 m wavelength and 50 m amplitude, and various types of rifts and crevasses. Internal layering is recorded at 250 to 300 m depth over Blåenga and i n the ice shelf up-stream of this ice rise. Observed ice thicknesses on Stancomb-Wills Ice Stream range from 130 to 220 m, with no systematic decrease towards the ice front. The records include long sections of heavy scatter from densely spaced rifts and bottom crevasses. This ice stream attains velocities > 4 km a−1, and is much more active than Riiser-Larsenisen. This high activity has resulted in extensive fracturing of the ice shelf.

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Airborne radio echo sounding of glaciers in Svalbard

Polar Record ◽

10.1017/s0032247400003405 ◽

1980 ◽

Vol 20 (126) ◽

pp. 261-266 ◽

Cited By ~ 14

Author(s):

D. J. Drewry ◽

O. Liestøl ◽

C. S. Neal ◽

O. Orheim ◽

B. Wold

Keyword(s):

Ice Thickness ◽

Wide Range ◽

Radio Echo Sounding ◽

Polar Research Institute ◽

Echo Sounding ◽

Research Institute

During April–May 1980 the Scott Polar Research Institute (SPRI) and Norsk Polarinstitutt (NPI) conducted a joint programme of radio echo sounding (RES) in Svalbard. The principal aims were to evaluate the performance of SPRI 60 MHz echo sounding equipment of Svalbard glaciers, to measure ice thickness over a wide range of conditions, and to investigate specific glaciers which are the focus of current glaciological studies.

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Comparison of measurements from different radio-echo sounding systems and synchronization with the ice core at Dome C, Antarctica

The Cryosphere ◽

10.5194/tc-11-653-2017 ◽

2017 ◽

Vol 11 (1) ◽

pp. 653-668 ◽

Cited By ~ 11

Author(s):

Anna Winter ◽

Daniel Steinhage ◽

Emily J. Arnold ◽

Donald D. Blankenship ◽

Marie G. P. Cavitte ◽

...

Keyword(s):

Ice Core ◽

Basal Layer ◽

Radar Data ◽

Sensitivity Study ◽

Data Set ◽

Range Resolution ◽

Radio Echo Sounding ◽

Conductivity Profile ◽

The Individual ◽

Echo Sounding

Abstract. We present a compilation of radio-echo sounding (RES) measurements of five radar systems (AWI, BAS, CReSIS, INGV and UTIG) around the EPICA Dome C (EDC) drill site, East Antarctica. The aim of our study is to investigate the differences of the various systems in their resolution of internal reflection horizons (IRHs) and bed topography, penetration depth and capacity of imaging the basal layer. We address the questions of the compatibility of existing radar data for common interpretation and the suitability of the individual systems for reconnaissance surveys. We find that the most distinct IRHs and IRH patterns can be identified and transferred between most data sets. Considerable differences between the RES systems exist in range resolution and depiction of the bottom-most region. Considering both aspects, which we judge as crucial factors in the search for old ice, the CReSIS and the UTIG systems are the most suitable ones. In addition to the RES data set comparison we calculate a synthetic radar trace from EDC density and conductivity profiles. We identify 10 common IRHs in the measured RES data and the synthetic trace. We then conduct a sensitivity study for which we remove certain peaks from the input conductivity profile. As a result the respective reflections disappear from the modeled radar trace. In this way, we establish a depth conversion of the measured travel times of the IRHs. Furthermore, we use these sensitivity studies to investigate the cause of observed reflections. The identified IRHs are assigned ages from the EDC's timescale. Due to the isochronous character of these conductivity-caused IRHs, they are a means to extend the Dome C age structure by tracing the IRHs along the RES profiles.

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