scholarly journals Miniature high-power impulse transmitter for radio-echo sounding

1994 ◽  
Vol 40 (134) ◽  
pp. 190-194 ◽  
Author(s):  
B. Barry Narod ◽  
Garry K.C. Clarke
Keyword(s):  
High Power ◽  
Yukon Territory ◽  
Ice Thickness ◽  
Maximum Dimension ◽  
Pulse Generators ◽  
Ice Cap ◽  
Bering Glacier ◽  
Radio Echo Sounding ◽  
Towed Arrays ◽  
Echo Sounding

AbstractWe have developed a miniature high-power impulse transmitter for radio-echo sounding of glaciers. It features two synchronous second break-down pulse generators operating in a differential configuration. Specifications include bipolar 550 V pulses having rise times less than 2 ns, 512 Hz repetition rate, 180 mA at 10-14 V d.c. operating power, 5 mA standby current and maximum dimension of 12 cm. Because of its small size and low power consumption, the transmitter is suitable for back-portable systems and for towed arrays. The transmitter first saw service in 1990 on Trapridge Glacier, Yukon Territory. Subsequent copies have been used on Agassiz Ice Cap, Northwest Territories, Bering Glacier, Alaska and elsewhere. To date, the maximum ice thickness measured using this transmitter is 825 m, on temperate Bering Glacier.

scholarly journals Miniature high-power impulse transmitter for radio-echo sounding

1994 ◽  
Vol 40 (134) ◽  
pp. 190-194 ◽  
Author(s):  
B. Barry Narod ◽  
Garry K.C. Clarke
Keyword(s):  
High Power ◽  
Yukon Territory ◽  
Ice Thickness ◽  
Maximum Dimension ◽  
Pulse Generators ◽  
Ice Cap ◽  
Bering Glacier ◽  
Radio Echo Sounding ◽  
Towed Arrays ◽  
Echo Sounding

AbstractWe have developed a miniature high-power impulse transmitter for radio-echo sounding of glaciers. It features two synchronous second break-down pulse generators operating in a differential configuration. Specifications include bipolar 550 V pulses having rise times less than 2 ns, 512 Hz repetition rate, 180 mA at 10-14 V d.c. operating power, 5 mA standby current and maximum dimension of 12 cm. Because of its small size and low power consumption, the transmitter is suitable for back-portable systems and for towed arrays. The transmitter first saw service in 1990 on Trapridge Glacier, Yukon Territory. Subsequent copies have been used on Agassiz Ice Cap, Northwest Territories, Bering Glacier, Alaska and elsewhere. To date, the maximum ice thickness measured using this transmitter is 825 m, on temperate Bering Glacier.

scholarly journals Results from the Radio Echo-Sounding on Parts of the Jostedalsbreen Ice Cap, Norway

1986 ◽  
Vol 8 ◽  
pp. 156-158 ◽  
Author(s):  
Arne Chr. Saetrang ◽  
Bjørn Wold
Keyword(s):  
Ice Thickness ◽  
Ice Cap ◽  
Radio Echo Sounding ◽  
Subglacial Topography ◽  
Echo Sounding

The paper describes instrumentation, navigation methods, and interpretation problems from radio echo-sounding on parts of Jostedalsbreen. A map of the subglacial topography is presented. Ice thickness ranges from 60 m to 600 m with most sections between 150 m and 300 m.

scholarly journals Results from the Radio Echo-Sounding on Parts of the Jostedalsbreen Ice Cap, Norway

1986 ◽  
Vol 8 ◽  
pp. 156-158 ◽  
Author(s):  
Arne Chr. Saetrang ◽  
Bjørn Wold
Keyword(s):  
Ice Thickness ◽  
Ice Cap ◽  
Radio Echo Sounding ◽  
Subglacial Topography ◽  
Echo Sounding

The paper describes instrumentation, navigation methods, and interpretation problems from radio echo-sounding on parts of Jostedalsbreen. A map of the subglacial topography is presented. Ice thickness ranges from 60 m to 600 m with most sections between 150 m and 300 m.

scholarly journals Radio Echo-Sounding of Spitsbergen Glaciers: Problems in the Interpretation of Layer and Bottom Returns

1984 ◽  
Vol 30 (104) ◽  
pp. 16-21 ◽  
Author(s):  
J. A. Dowdeswell ◽  
D.J. Drewry ◽  
O. Liestøl ◽  
O. Orheim
Keyword(s):  
Melting Point ◽  
Water Content ◽  
Ice Thickness ◽  
Drill Core ◽  
Ice Cap ◽  
Radio Echo Sounding ◽  
Pressure Melting ◽  
Radio Frequencies ◽  
Similar Depth ◽  
Echo Sounding

AbstractAirborne radio echo-sounding of Spitsbergen glaciers during 1980 used 60 MHz SPR1 Mk IV equipment. On several glaciers results showed unambiguous bottom returns at depths 2–3 times those reported in previous Soviet echo-sounding at 440 and 620 MHz. Comparison of 60 MHZ records and independent gravity-surveyed ice thickness for two glaciers agreed to within 10%, whereas Soviet ice thicknesses were only 30–60% of gravity depths. Soviet bed echoes often coincided closely with an internal reflecting horizon recorded by the SPRI Mk IV system, and it is shown that Soviet U.H.F. equipment failed to penetrate to the true glacier bed on a number of ice masses (e.g. Finsterwalderbreen, Kongsvegen, Negribreen). This was probably due to increased absorption and scattering at higher radio frequencies, related to the inhomogeneous nature of Spitsbergen glaciers, which are often at or near the pressure-melting point. Both 60 MHz and U.H.F. equipment seldom recorded bed echoes in ice-cap accumulation areas (e.g. Isachsenfonna), where firn soaking during summer and 10 m temperatures of zero degrees have been observed. An isolated internal reflecting horizon was recorded on many glaciers. It is unlikely to be a moraine layer, but may be related to ice with a water content of 1–2% observed at a similar depth (115 m) in a drill core from Fridtjovbreen.

A 1976 radio echo sounding expedition to the Vatnajökull ice cap, Iceland

Polar Record ◽  
1977 ◽  
Vol 18 (115) ◽  
pp. 375-377 ◽  
Author(s):  
H. Björnsson ◽  
R. L. Ferrari ◽  
K. J. Miller ◽  
G. Owen
Keyword(s):  
Ice Thickness ◽  
First Year ◽  
Detailed Knowledge ◽  
Polar Regions ◽  
Related Data ◽  
Ice Cap ◽  
Geothermal Activity ◽  
Radio Echo Sounding ◽  
Depth Sounding ◽  
Echo Sounding

This brief report describes the first year of a joint Cambridge University—Iceland University two-year project to develop radio echo depth-sounding apparatus suitable for the temperate ice of the Vatnajökull ice cap. There is much interest in obtaining detailed ice thickness measurements for the 8 400 km2 Vatnajökull area, where only limited ice-depth surveys, using bore-hole and seismxic techniques, have been carried out in the past. A line of volcanic and geothermal activity extends through the western regions of the ice and creates a sub-glacial lake, Grimsvotn, which collapses every five years or so giving rise to the jökulhlaups, a catastrophic flooding which affects considerable areas of the Icelandic coast to the south of Vatnajökull. Proper understanding of the jökulhlaups phenomena can only be achieved if detailed knowledge of ice thickness and related data are available. Established radio echo sounding techniques which have been successfully applied in the polar regions do not work in water-laden ice such as is to be found in the Vatnajökull area.

The 1981 – 1982 surge of Hazard Glacier, Yukon Territory

1984 ◽  
Vol 21 (3) ◽  
pp. 297-304 ◽  
Author(s):  
Garry K. C. Clarke ◽  
Sam G. Collins
Keyword(s):  
Melting Point ◽  
Dimensional Analysis ◽  
Yukon Territory ◽  
Ice Thickness ◽  
Depth Profiles ◽  
The Third ◽  
Radio Echo Sounding ◽  
Echo Sounding

A surge of Hazard Glacier, believed to have started in 1981, displaced ice as much as 0.7 km. Before the surge, ice thickness was measured by radio echo sounding and temperatures were taken in three holes to the glacier bed. The glacier is subpolar with 10 m temperatures near −5.4 °C, and temperature versus depth profiles show many anomalous features. We attribute these anomalies to various effects of past surges and to ablation at the upper surface. The interpretations are supported by simple calculations derived from dimensional analysis. Part of the glacier is warm based: at two sites the basal temperature was at the melting point; at the third site, upstream from the others, it was −2.70 °C.

Surface and Bedrock Topography of Ice Caps in Iceland, Mapped by Radio Echo-Sounding

1986 ◽  
Vol 8 ◽  
pp. 11-18 ◽  
Author(s):  
Helgi Björnsson
Keyword(s):  
Surface Elevation ◽  
Ice Thickness ◽  
Volcanic Complex ◽  
Glacier Surface ◽  
Ice Caps ◽  
Ice Cap ◽  
North East ◽  
Ice Surface ◽  
Radio Echo Sounding ◽  
Echo Sounding

Since 1977, large areas on western Vatnajökull have been surveyed by ground-based, radio echo-sounding and the whole ice cap, HofsjökuIl, was surveyed in 1983. Detailed maps of the glacier-surface elevation and the sub-ice bedrock have been compiled. The instrumentation includes a 2–5 MHz, mono-pulse echo-sounder, for continuous profiling, a satellite geoceiver and Loran-C equipment, for navigation, and a precision pressure altimeter. The maps of western Vatnajökull cover about 1500 km2 and are compiled from 1500 km-long sounding lines, which yielded about 50 000 data points for ice thickness and 20 000 points for ice-surface elevation. The maps of HofsjökuIl cover 923 km2, the sounding lines were 1350 km long; 42 000 points were used for determining ice thickness and 30 000 for surface elevation. The maps obtained from these data are the first ones of the ice caps with surface elevation of known accuracy. The bedrock map of western Vatnajökull shows details of volcanic ridges and subglacial valleys, running north-east to south-west, as well as the central, volcanic complexes, Hamarinn, Bárdarbunga, and Grimsvtön and the related fissure swarms. The map of Hofsjökull reveals a large volcanic complex, with a 650 m deep caldera. The landforms in southern Hofsjökull are predominantly aligned from north to south, but those in the northern ice cap run north by 25° east.

scholarly journals Surface and Bedrock Topography of Ice Caps in Iceland, Mapped by Radio Echo-Sounding

1986 ◽  
Vol 8 ◽  
pp. 11-18 ◽  
Author(s):  
Helgi Björnsson
Keyword(s):  
Surface Elevation ◽  
Ice Thickness ◽  
Volcanic Complex ◽  
Glacier Surface ◽  
Ice Caps ◽  
Ice Cap ◽  
North East ◽  
Ice Surface ◽  
Radio Echo Sounding ◽  
Echo Sounding

Since 1977, large areas on western Vatnajökull have been surveyed by ground-based, radio echo-sounding and the whole ice cap, HofsjökuIl, was surveyed in 1983. Detailed maps of the glacier-surface elevation and the sub-ice bedrock have been compiled. The instrumentation includes a 2–5 MHz, mono-pulse echo-sounder, for continuous profiling, a satellite geoceiver and Loran-C equipment, for navigation, and a precision pressure altimeter. The maps of western Vatnajökull cover about 1500 km2 and are compiled from 1500 km-long sounding lines, which yielded about 50 000 data points for ice thickness and 20 000 points for ice-surface elevation. The maps of HofsjökuIl cover 923 km2, the sounding lines were 1350 km long; 42 000 points were used for determining ice thickness and 30 000 for surface elevation. The maps obtained from these data are the first ones of the ice caps with surface elevation of known accuracy. The bedrock map of western Vatnajökull shows details of volcanic ridges and subglacial valleys, running north-east to south-west, as well as the central, volcanic complexes, Hamarinn, Bárdarbunga, and Grimsvtön and the related fissure swarms. The map of Hofsjökull reveals a large volcanic complex, with a 650 m deep caldera. The landforms in southern Hofsjökull are predominantly aligned from north to south, but those in the northern ice cap run north by 25° east.

scholarly journals Ice thickness, internal structure and subglacial topography of Bowles Plateau ice cap and the main ice divides of Livingston Island, Antarctica, by ground-based radio-echo sounding

2009 ◽  
Vol 50 (51) ◽  
pp. 49-56 ◽  
Author(s):  
Yu.Ya. Macheret ◽  
J. Otero ◽  
F.J. Navarro ◽  
E.V. Vasilenko ◽  
M.I. Corcuera ◽  
...  
Keyword(s):  
Internal Structure ◽  
Sea Level ◽  
Low Frequency ◽  
South Shetland Islands ◽  
Ice Thickness ◽  
Radio Waves ◽  
Ice Cap ◽  
Livingston Island ◽  
Radio Echo Sounding ◽  
Echo Sounding

AbstractWe present the results of low-frequency (20 MHz) radio-echo sounding (RES) carried out in December 2000 and December 2006 on the main ice divides of Livingston Island, South Shetland Islands (SSI), Antarctica, and Bowles Plateau, Antarctica, respectively, as well as high-frequency (200 MHz) RES on the latter, aimed at determining the ice thickness, internal structure and subglacial relief. Typical ice thickness along the main ice divides is ~150 m, reaching maxima of ~200 m. On Bowles Plateau the ice is much thicker, with an average of 265 m and maxima of ~500 m. The bed below the main ice divides is above sea level, while part of the outlet glaciers from Bowles Plateau lies significantly below sea level, down to –120 m. The strong scattering of the radio waves in the areas under study constitutes further evidence that the ice in the accumulation area of the ice masses of the SSI is temperate. Typical thickness of the firn layer in Bowles Plateau is 20–35 m, similar to that found in King George ice cap. A strong internal reflector within the firn layer, interpreted as a tephra layer from the 1970 eruption at Deception Island, has allowed a rough estimate of the specific mass balances for Bowles Plateau within 0.20–0.40ma–1w.e., as average values for the period 1970–2006.

scholarly journals Radio Echo-Sounding of Spitsbergen Glaciers: Problems in the Interpretation of Layer and Bottom Returns

1984 ◽  
Vol 30 (104) ◽  
pp. 16-21 ◽  
Author(s):  
J. A. Dowdeswell ◽  
D.J. Drewry ◽  
O. Liestøl ◽  
O. Orheim
Keyword(s):  
Melting Point ◽  
Water Content ◽  
Ice Thickness ◽  
Drill Core ◽  
Ice Cap ◽  
Radio Echo Sounding ◽  
Pressure Melting ◽  
Radio Frequencies ◽  
Similar Depth ◽  
Echo Sounding

AbstractAirborne radio echo-sounding of Spitsbergen glaciers during 1980 used 60 MHz SPR1 Mk IV equipment. On several glaciers results showed unambiguous bottom returns at depths 2–3 times those reported in previous Soviet echo-sounding at 440 and 620 MHz. Comparison of 60 MHZ records and independent gravity-surveyed ice thickness for two glaciers agreed to within 10%, whereas Soviet ice thicknesses were only 30–60% of gravity depths. Soviet bed echoes often coincided closely with an internal reflecting horizon recorded by the SPRI Mk IV system, and it is shown that Soviet U.H.F. equipment failed to penetrate to the true glacier bed on a number of ice masses (e.g. Finsterwalderbreen, Kongsvegen, Negribreen). This was probably due to increased absorption and scattering at higher radio frequencies, related to the inhomogeneous nature of Spitsbergen glaciers, which are often at or near the pressure-melting point. Both 60 MHz and U.H.F. equipment seldom recorded bed echoes in ice-cap accumulation areas (e.g. Isachsenfonna), where firn soaking during summer and 10 m temperatures of zero degrees have been observed. An isolated internal reflecting horizon was recorded on many glaciers. It is unlikely to be a moraine layer, but may be related to ice with a water content of 1–2% observed at a similar depth (115 m) in a drill core from Fridtjovbreen.

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