scholarly journals 50 MHz helicopter-borne radar data for determination of glacier thermal regime in the central Chilean Andes

2015 ◽  
Vol 56 (70) ◽  
pp. 193-201 ◽  
Author(s):  
Guisella Gacitúa ◽  
José A. Uribe ◽  
Ryan Wilson ◽  
Thomas Loriaux ◽  
Jorge Hernández ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Radar Data ◽  
Ice Thickness ◽  
Ice Dynamics ◽  
Central Chile ◽  
Glacier Ice ◽  
Ground Penetrating ◽  
Further Development ◽  
Chilean Andes

AbstractDespite their importance as freshwater reservoirs for downstream river systems, few glaciers in central Chile have been comprehensively surveyed. This study presents ground-penetrating radar (GPR) and field-based observations for characterizing the englacial and basal conditions of Glaciar Olivares Alfa (33°110 S, 70°130 W), central Chilean Andes. Using a 50 MHz radar mounted onto a helicopter platform, data were collected covering large portions of the glacier accumulation and ablation zones. The radar data revealed boundaries of a temperate-ice layer at the base of the eastern body of Glaciar Olivares Alfa which appears to be covered by colder ice that extends throughout large parts of the glacier. The thickness of the temperate ice layer is highly variable across the glacier, being on average 40% of the total ice thickness. Radar data analyses reveal regions of cold ice at the bottom/base of the glacier and also patterns of highly saturated sediments beneath the glacier. Using GPR data, this study represents the most exhaustive analysis of glacier ice structure performed in the central Chilean Andes. The results will enable improved estimations of the glacier’s mass balance and ice dynamics, helping us to understand its further development and its impact on water availability.

scholarly journals Ice thickness distribution of all Swiss glaciers based on extended ground-penetrating radar data and glaciological modeling

2021 ◽  
pp. 1-19
Author(s):  
Melchior Grab ◽  
Enrico Mattea ◽  
Andreas Bauder ◽  
Matthias Huss ◽  
Lasse Rabenstein ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Thickness Distribution ◽  
Radar Data ◽  
Tourism Industry ◽  
Swiss Alps ◽  
Ice Thickness ◽  
Hazard Management ◽  
Bed Topography ◽  
Ice Volume ◽  
Ground Penetrating

Abstract Accurate knowledge of the ice thickness distribution and glacier bed topography is essential for predicting dynamic glacier changes and the future developments of downstream hydrology, which are impacting the energy sector, tourism industry and natural hazard management. Using AIR-ETH, a new helicopter-borne ground-penetrating radar (GPR) platform, we measured the ice thickness of all large and most medium-sized glaciers in the Swiss Alps during the years 2016–20. Most of these had either never or only partially been surveyed before. With this new dataset, 251 glaciers – making up 81% of the glacierized area – are now covered by GPR surveys. For obtaining a comprehensive estimate of the overall glacier ice volume, ice thickness distribution and glacier bed topography, we combined this large amount of data with two independent modeling algorithms. This resulted in new maps of the glacier bed topography with unprecedented accuracy. The total glacier volume in the Swiss Alps was determined to be 58.7 ± 2.5 km3 in the year 2016. By projecting these results based on mass-balance data, we estimated a total ice volume of 52.9 ± 2.7 km3 for the year 2020. Data and modeling results are accessible in the form of the SwissGlacierThickness-R2020 data package.

scholarly journals Pervasive cold ice within a temperate glacier – implications for glacier thermal regimes, sediment transport and foreland geomorphology

2019 ◽  
Vol 13 (3) ◽  
pp. 827-843 ◽  
Author(s):  
Benedict T. I. Reinardy ◽  
Adam D. Booth ◽  
Anna L. C. Hughes ◽  
Clare M. Boston ◽  
Henning Åkesson ◽  
...  
Keyword(s):  
Climate Warming ◽  
Ground Penetrating Radar ◽  
Radar Data ◽  
Ice Thickness ◽  
Systematic Mapping ◽  
Ablation Area ◽  
Seasonal Snow ◽  
Thermal Regimes ◽  
Subglacial Topography ◽  
Ground Penetrating

Abstract. This study suggests that cold-ice processes may be more widespread than previously assumed, even within temperate glacial systems. We present the first systematic mapping of cold ice at the snout of the temperate glacier Midtdalsbreen, an outlet of the Hardangerjøkulen icefield (Norway), from 43 line kilometres of ground-penetrating radar data. Results show a 40 m wide cold-ice zone within the majority of the glacier snout, where ice thickness is <10 m. We interpret ice to be cold-based across this zone, consistent with basal freeze-on processes involved in the deposition of moraines. We also find at least two zones of cold ice up to 15 m thick within the ablation area, occasionally extending to the glacier bed. There are two further zones of cold ice up to 30 m thick in the accumulation area, also extending to the glacier bed. Cold-ice zones in the ablation area tend to correspond to areas of the glacier that are covered by late-lying seasonal snow patches that reoccur over multiple years. Subglacial topography and the location of the freezing isotherm within the glacier and underlying subglacial strata likely influence the transport and supply of supraglacial debris and formation of controlled moraines. The wider implication of this study is the possibility that, with continued climate warming, temperate environments with primarily temperate glaciers could become polythermal in forthcoming decades with (i) persisting thinning and (ii) retreat to higher altitudes where subglacial permafrost could be and/or become more widespread. Adversely, the number and size of late-lying snow patches in ablation areas may decrease and thereby reduce the extent of cold ice, reinforcing the postulated change in the thermal regime.

scholarly journals Targeted reflection-waveform inversion of experimental ground-penetrating radar data for quantification of oil spills under sea ice

Geophysics ◽  
2016 ◽  
Vol 81 (1) ◽  
pp. WA59-WA70 ◽  
Author(s):  
John H. Bradford ◽  
Esther L. Babcock ◽  
Hans-Peter Marshall ◽  
David F. Dickins
Keyword(s):  
Sea Ice ◽  
Ground Penetrating Radar ◽  
Oil Spills ◽  
Waveform Inversion ◽  
Radar Data ◽  
The Arctic ◽  
Ice Thickness ◽  
Inversion Algorithm ◽  
Control Value ◽  
Ground Penetrating

Rapid spill detection and mapping are needed with increasing levels of oil exploration and production in the Arctic. Previous work has found that ground-penetrating radar (GPR) is effective for qualitative identification of oil spills under, and encapsulated within, sea ice. Quantifying the spill distribution will aid effective spill response. To this end, we have developed a targeted GPR reflection-waveform inversion algorithm to quantify the geometry of oil spills under and within sea ice. With known electric properties of the ice and oil, we have inverted for oil thickness and variations in ice thickness. We have tested the algorithm with data collected during a controlled spill experiment using 500-MHz radar reflection data. The algorithm simultaneously recovered the thickness of a 5-cm-thick oil layer at the base of the ice to within 8% of the control value, estimated the thickness of a 1-cm-thick oil layer encapsulated within the ice to within 30% of the control value, and accurately mapped centimeter-scale variations in ice thickness.

scholarly journals Spatial distribution of cold-ice within a temperate glacier – implications for glacier dynamics, sediment transport and foreland geomorphology

2018 ◽  
Author(s):  
Benedict T. I. Reinardy ◽  
Adam Booth ◽  
Anna Hughes ◽  
Clare M. Boston ◽  
Henning Åkesson ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Sediment Transport ◽  
Ground Penetrating Radar ◽  
Radar Data ◽  
Ice Thickness ◽  
Direct Observations ◽  
Glacier Dynamics ◽  
Ground Penetrating

Abstract. This study suggests that cold-ice processes may be more widespread even within temperate glacial systems, than previously assumed. We present the first direct observations of cold-ice at the snout of the temperate glacier Midtdalsbreen an outlet of the Hardangerjøkulen icefield (Norway) from 43 line-kilometres of ground penetrating radar data. Results show a 40 m-wide cold-ice zone within the majority of the glacier snout, where ice thickness is

Removal of wavelet dispersion from ground‐penetrating radar data

Geophysics ◽  
2003 ◽  
Vol 68 (3) ◽  
pp. 960-970 ◽  
Author(s):  
James D. Irving ◽  
Rosemary J. Knight
Keyword(s):  
Ground Penetrating Radar ◽  
Electromagnetic Waves ◽  
Radar Data ◽  
Dominant Frequency ◽  
Seismic Attenuation ◽  
Inverse Q Filtering ◽  
Damped Least Squares ◽  
Ground Penetrating ◽  
Seismic Attenuation Tomography

Wavelet dispersion caused by frequency‐dependent attenuation is a common occurrence in ground‐penetrating radar (GPR) data, and is displayed in the radar image as a characteristic “blurriness” that increases with depth. Correcting for wavelet dispersion is an important step that should be performed before GPR data are used for either qualitative interpretation or the quantitative determination of subsurface electrical properties. Over the bandwidth of a GPR wavelet, the attenuation of electromagnetic waves in many geological materials is approximately linear with frequency. As a result, the change in shape of a radar pulse as it propagates through these materials can be well described using one parameter, Q*, related to the slope of the linear region. Assuming that all subsurface materials can be characterized by some Q* value, the problem of estimating and correcting for wavelet dispersion becomes one of determining Q* in the subsurface and deconvolving its effects using an inverse‐Q filter. We present a method for the estimation of subsurface Q* from reflection GPR data based on a technique developed for seismic attenuation tomography. Essentially, Q* is computed from the downshift in the dominant frequency of the GPR signal with time. Once Q* has been obtained, we propose a damped‐least‐squares inverse‐Q filtering scheme based on a causal, linear model for constant‐Q wave propagation as a means of removing wavelet dispersion. Tests on synthetic and field data indicate that these steps can be very effective at enhancing the resolution of the GPR image.

scholarly journals Detecting and Measuring Internal Anomalies in Tree Trunks Using Radar Data for Layer Identification

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Xiayang Xiao ◽  
Jian Wen ◽  
Zhongliang Xiao ◽  
Weilin Li
Keyword(s):  
Ground Penetrating Radar ◽  
Measurement Method ◽  
Matched Filter ◽  
Laser Scanner ◽  
Radar Data ◽  
Summer Palace ◽  
Ground Penetrating ◽  
Wooden Structures

Radar detection has proven to be an effective, nondestructive test for the determination of the quality of wood-based materials, especially in the wooden structures of ancient buildings and trees. However, the results are usually inaccurate, and it is difficult to interpret internal anomalies due to the moisture content of wood, individual differences, and other factors. In this paper, a new measurement method is proposed based on the use of ground-penetrating radar (GPR) for abnormality localization and imaging. Firstly, the time delay of the reflected signal in the inner trees is analyzed with matched filter and Hilbert detections. Secondly, the two approaches are compared with the use of a forward model, and the Hilbert algorithm is found to be more accurate. Thirdly, a laser scanner is used to collect contour data and determine the location and characteristics of internal tree anomalies. Lastly, the proposed method is tested on ancient willows at the Summer Palace. The results show that the error in the depth and area estimates of the anomalies was within 10% and 5%, respectively. Consequently, the GPR method for locating the anomalies in trees is feasible, and a laser scanner combined with contour data can present the size of the abnormal regions within the trees.

scholarly journals Ground-penetrating radar studies in Svalbard aimed to the calculation of the ice volume of its glaciers

2016 ◽  
Vol 42 (2) ◽  
pp. 399 ◽  
Author(s):  
F. J. Navarro ◽  
J. Lapazaran ◽  
A. Martín-Español ◽  
J. Otero
Keyword(s):  
Numerical Simulation ◽  
Physical Properties ◽  
Sea Level ◽  
Ground Penetrating Radar ◽  
Ice Thickness ◽  
Ice Volume ◽  
Glacier Ice ◽  
Ground Penetrating

During the period 1999-2014, the Group of Numerical Simulation in Sciences and Engineering of Universidad Politécnica de Madrid carried out many ground-penetrating radar campaigns in Svalbard, aimed to the study of glacier ice-thickness and the physical properties of glacier ice. The regions covered were Nordenskiöld Land, Wedel Jarlsberg Land, Sabine Land and Nordaustlandet. We here present a review of these works, focused on the aspects related to the estimate of the volume of individual glaciers and its extrapolation to the entire set of Svalbard glaciers, for which the authors estimate a total volume of 6700±835 km3, o 17±2 mm in sea-level equivalent.

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