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.

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.

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 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.

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 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.

Airborne UHF Radio Echo-Sounding of Three Yukon Glaciers

1980 ◽  
Vol 25 (91) ◽  
pp. 23-32 ◽  
Author(s):  
B. B Narod ◽  
G. K. C. Clarke
Keyword(s):  
Field Trials ◽  
High Gain ◽  
Yukon Territory ◽  
Ice Thickness ◽  
Spatial Averaging ◽  
Ice Caps ◽  
Signal Degradation ◽  
High Gain Antenna ◽  
Radio Echo Sounding ◽  
Moving Platform

AbstractA high-resolution radio echo-sounder operating at a frequency of 840 MHz has been developed for airborne sounding of small and medium-sized polar glaciers and ice caps. The sounder uses a compact,, high-gain antenna which suppresses valley-wall echoes and simplifies operation from light aircraft, Successful field trials were carried out on Rusty, Trapridge, and Hazard Glaciers, Yukon Territory, Canada. Results compare well with ice depths obtained from earlier ground-based soundings on Rusty and Trapridge Glaciers. The maximum ice thickness encountered was 200 m on Hazard Glacier.Owing to the high operating frequency, random scattering from inhomogeneities within the ice is a major cause of signal degradation. For this reason the sounder cannot penetrate great thicknesses of temperate or debris-rich ice. Spatial averaging, an immediate result of operating from a moving platform, reduces the effects of back-scattered “clutter”.

scholarly journals New maps of the ice thickness and subglacial topography in Dronning Maud Land, Antarctica, determined by means of airborne radio-echo sounding

1999 ◽  
Vol 29 ◽  
pp. 267-272 ◽  
Author(s):  
D. Steinhage ◽  
U. Nixdorf ◽  
U. Meyer ◽  
H. Miller
Keyword(s):  
Three Dimensional ◽  
Austral Summer ◽  
Ice Thickness ◽  
Ice Volume ◽  
Site Survey ◽  
Radio Echo Sounding ◽  
First Results ◽  
Dronning Maud Land ◽  
Subglacial Topography ◽  
Echo Sounding

AbstractSince the austral summer of 1994-95 the Alfred Wegener Institute has carried out airborne radio-echo sounding (RES) measurements in Antarctica with its newly designed RES system. Since 1995-96 an ongoing pre-site survey for an ice-coring drill site in Dronning Maud Land has been carried out as part of the European Project for Ice Goring in Antarctica. The survey covers an area of 948 000 km2, with >49 500 km of airborne RES obtained from >200 hours of flight operation flown during the period 1994-97. In this paper, first results of the airborne RES survey are graphically summarized as newly derived maps of the ice thickness and subglacial topography, as well as a three-dimensional view of surface and subglacial bed and outcrop topography, revealing a total ice volume of 1.48 x 106 km3.

scholarly journals A revised inventory of Antarctic subglacial lakes

2005 ◽  
Vol 17 (3) ◽  
pp. 453-460 ◽  
Author(s):  
MARTIN J. SIEGERT ◽  
SASHA CARTER ◽  
IGNAZIO TABACCO ◽  
SERGEY POPOV ◽  
DONALD D. BLANKENSHIP
Keyword(s):  
East Antarctica ◽  
Large Lake ◽  
Dome A ◽  
Lake Vostok ◽  
The Third ◽  
The Us ◽  
Radio Echo Sounding ◽  
Subglacial Lakes ◽  
Lake Type ◽  
Echo Sounding

The locations and details of 145 Antarctic subglacial lakes are presented. The inventory is based on a former catalogue of lake-type features, which has been subsequently reanalysed, and on the results from three additional datasets. The first is from Italian radio-echo sounding (RES) of the Dome C region of East Antarctica, from which 14 new lakes are identified. These data also show that, in a number of occasions, multiple lake-type reflectors thought previously to be individual lakes are in fact reflections from the same relatively large lake. This reduces the former total of lake-type reflectors by six, but also adds a significant level of information to these particular lakes. The second dataset is from a Russian survey of the Dome A and Dome F regions of East Antarctica, which provides evidence of 18 new lakes and extends the coverage of the inventory considerably. The third dataset comprises three airborne RES surveys undertaken by the US in East Antarctica over the last five years, from which forty three new lakes have been identified. Reference to information on Lake Vostok, from Italian and US surveys taken in the last few years, is now included.

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.

Sign in / Sign up

Export Citation Format

Share Document