scholarly journals Melt regimes, stratigraphy, flow dynamics and glaciochemistry of three glaciers in the Alaska Range

2012 ◽  
Vol 58 (207) ◽  
pp. 99-109 ◽  
Author(s):  
Seth Campbell ◽  
Karl Kreutz ◽  
Erich Osterberg ◽  
Steven Arcone ◽  
Cameron Wake ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Ice Core ◽  
Chemical Diffusion ◽  
Flow Dynamics ◽  
Alaska Range ◽  
Ice Volume ◽  
Glacier Ice ◽  
Age Model ◽  
Ground Penetrating ◽  
Climate Studies

AbstractWe used ground-penetrating radar (GPR), GPS and glaciochemistry to evaluate melt regimes and ice depths, important variables for mass-balance and ice-volume studies, of Upper Yentna Glacier, Upper Kahiltna Glacier and the Mount Hunter ice divide, Alaska. We show the wet, percolation and dry snow zones located below ~2700ma.s.l., at ~2700 to 3900ma.s.l. and above 3900ma.s.l., respectively. We successfully imaged glacier ice depths upwards of 480 m using 40-100 MHz GPR frequencies. This depth is nearly double previous depth measurements reached using mid-frequency GPR systems on temperate glaciers. Few Holocene-length climate records are available in Alaska, hence we also assess stratigraphy and flow dynamics at each study site as a potential ice-core location. Ice layers in shallow firn cores and attenuated glaciochemical signals or lacking strata in GPR profiles collected on Upper Yentna Glacier suggest that regions below 2800ma.s.l. are inappropriate for paleoclimate studies because of chemical diffusion, through melt. Flow complexities on Kahiltna Glacier preclude ice-core climate studies. Minimal signs of melt or deformation, and depth-age model estimates suggesting ~4815 years of ice on the Mount Hunter ice divide (3912ma.s.l.) make it a suitable Holocene-age ice-core location.

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.

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 Reconstruction of historical surface mass balance, 1984–2017 from GreenTrACS multi-offset ground-penetrating radar

2020 ◽  
pp. 1-10
Author(s):  
Tate G. Meehan ◽  
H. P. Marshall ◽  
John H. Bradford ◽  
Robert L. Hawley ◽  
Thomas B. Overly ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ground Penetrating Radar ◽  
Greenland Ice Sheet ◽  
Snow Accumulation ◽  
Surface Mass Balance ◽  
Snow Density ◽  
Surface Mass ◽  
Age Model ◽  
Ground Penetrating ◽  
Good Agreement

Abstract We present continuous estimates of snow and firn density, layer depth and accumulation from a multi-channel, multi-offset, ground-penetrating radar traverse. Our method uses the electromagnetic velocity, estimated from waveform travel-times measured at common-midpoints between sources and receivers. Previously, common-midpoint radar experiments on ice sheets have been limited to point observations. We completed radar velocity analysis in the upper ~2 m to estimate the surface and average snow density of the Greenland Ice Sheet. We parameterized the Herron and Langway (1980) firn density and age model using the radar-derived snow density, radar-derived surface mass balance (2015–2017) and reanalysis-derived temperature data. We applied structure-oriented filtering to the radar image along constant age horizons and increased the depth at which horizons could be reliably interpreted. We reconstructed the historical instantaneous surface mass balance, which we averaged into annual and multidecadal products along a 78 km traverse for the period 1984–2017. We found good agreement between our physically constrained parameterization and a firn core collected from the dry snow accumulation zone, and gained insights into the spatial correlation of surface snow density.

scholarly journals On the errors involved in ice-thickness estimates I: ground-penetrating radar measurement errors

2016 ◽  
Vol 62 (236) ◽  
pp. 1008-1020 ◽  
Author(s):  
J.J. LAPAZARAN ◽  
J. OTERO ◽  
A. MARTÍN-ESPAÑOL ◽  
F.J. NAVARRO
Keyword(s):  
Ground Penetrating Radar ◽  
Measurement Errors ◽  
Ice Thickness ◽  
Independent Components ◽  
Ice Volume ◽  
Thickness Error ◽  
Grid Points ◽  
Ground Penetrating ◽  
Volume Estimates

ABSTRACTThis is the first (Paper I) of three companion papers focused respectively, on the estimates of the errors in ice thickness retrieved from pulsed ground-penetrating radar (GPR) data, on how to estimate the errors at the grid points of an ice-thickness DEM, and on how the latter errors, plus the boundary delineation errors, affect the ice-volume estimates. We here present a comprehensive analysis of the various errors involved in the computation of ice thickness from pulsed GPR data, assuming they have been properly migrated. We split the ice-thickness error into independent components that can be estimated separately. We consider, among others, the effects of the errors in radio-wave velocity and timing. A novel aspect is the estimate of the error in thickness due to the uncertainty in horizontal positioning of the GPR measurements, based on the local thickness gradient. Another novel contribution is the estimate of the horizontal positioning error of the GPR measurements due to the velocity of the GPR system while profiling, and the periods of GPS refreshing and GPR triggering. Their effects are particularly important for airborne profiling. We illustrate our methodology through a case study of Werenskioldbreen, Svalbard.

scholarly journals Ice volume changes (1936–1990–2007) and ground-penetrating radar studies of Ariebreen, Hornsund, Spitsbergen

2013 ◽  
Vol 32 (1) ◽  
pp. 11068 ◽  
Author(s):  
Javier Lapazaran ◽  
Michal Petlicki ◽  
Francisco Navarro ◽  
Francisco Machío ◽  
Darek Puczko ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Volume Changes ◽  
Ice Volume ◽  
Ground Penetrating

scholarly journals Changes in glacier facies zonation on Devon Ice Cap, Nunavut, detected from SAR imagery and field observations

2018 ◽  
Author(s):  
Tyler de Jong ◽  
Luke Copland ◽  
David Burgess
Keyword(s):  
Ice Core ◽  
Envisat Asar ◽  
Ice Cap ◽  
Meltwater Runoff ◽  
Devon Ice Cap ◽  
Glacier Ice ◽  
High Backscatter ◽  
Sar Imagery ◽  
Ground Penetrating ◽  
Line Switching

Abstract. Envisat ASAR WS images, verified against mass balance, ice core, ground-penetrating radar and air temperature measurements, are used to map changes in the distribution of glacier facies zones across Devon Ice Cap between 2004 and 2011. Glacier ice, saturation/percolation and pseudo dry snow zones are readily distinguishable in the satellite imagery, and the superimposed ice zone can be mapped after comparison with ground measurements. Over the study period there has been a clear upglacier migration of glacier facies, resulting in regions close to the firn line switching from being part of the accumulation area with high backscatter to being part of the ablation area with relatively low backscatter. This has coincided with a rapid increase in positive degree days near the ice cap summit, and an increase in the glacier ice zone from 71 % of the ice cap in 2005 to 92 % of the ice cap in 2011. This has significant implications for the area of the ice cap subject to meltwater runoff.

Cosmogenic nuclide exposure age constraints on the glacial history of the Lake Wellman area, Darwin Mountains, Antarctica

2010 ◽  
Vol 22 (6) ◽  
pp. 603-618 ◽  
Author(s):  
B.C. Storey ◽  
D. Fink ◽  
D. Hood ◽  
K. Joy ◽  
J. Shulmeister ◽  
...  
Keyword(s):  
Ross Ice Shelf ◽  
Ice Volume ◽  
Model Interpretation ◽  
Ice Surface ◽  
Exposure Age ◽  
Glacier Ice ◽  
History Of ◽  
Age Model ◽  
Elevation Model ◽  
Exposure Ages

AbstractWe present direct terrestrial evidence of ice volume change of the Darwin and Hatherton glaciers which channel ice from the Transantarctic Mountains into the Ross Ice Shelf. Combining glacial geomorphology with cosmogenic exposure ages from 25 erratics indicates a pre-LGM ice volume at least 600 m thicker than current Hatherton ice elevation was established at least 2.2 million years ago. In particular, five erratics spread across a drift deposit at intermediate elevations located below a prominent moraine feature mapped previously as demarcating the LGM ice advance limits, give a well-constrained single population with mean 10Be age of 37.0 ± 5.5 ka (1σ). At lower elevations of 50–100 m above the surface of Lake Wellman, a further five samples from within a younger drift deposit range in exposure age from 1 to 19 ka. Our preferred age model interpretation, which is partly dependent on the selection of a minimum or maximum age-elevation model, suggests that LGM ice volume was not as large as previously estimated and constrains LGM ice elevation to be within ± 50 m of the modern Hatherton Glacier ice surface, effectively little different from what is observed today.

scholarly journals Recent accumulation variability in northwest Greenland from ground-penetrating radar and shallow cores along the Greenland Inland Traverse

2014 ◽  
Vol 60 (220) ◽  
pp. 375-382 ◽  
Author(s):  
Robert L. Hawley ◽  
Zoe R. Courville ◽  
Laura M. Kehrl ◽  
Eric R. Lutz ◽  
Erich C. Osterberg ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Spatial Scales ◽  
Ice Core ◽  
Greenland Ice Sheet ◽  
Accumulation Rates ◽  
Density Profiles ◽  
Direct Measurements ◽  
Point Data ◽  
Ground Penetrating ◽  
Key Parameter

AbstractAccumulation is a key parameter governing the mass balance of the Greenland ice sheet. Several studies have documented the spatial variability of accumulation over wide spatial scales, primarily using point data, remote sensing or modeling. Direct measurements of spatially extensive, detailed profiles of accumulation in Greenland, however, are rare. We used 400 MHz ground-penetrating radar along the 1009 km route of the Greenland Inland Traverse from Thule to Summit during April and May of 2011, to image continuous internal reflecting horizons. We dated these horizons using ice-core chemistry at each end of the traverse. Using density profiles measured along the traverse, we determined the depth to the horizons and the corresponding water-equivalent accumulation rates. The measured accumulation rates vary from ~0.1 m w.e. a–1 in the interior to ~0.7 m w.e. a–1 near the coast, and correspond broadly with existing published model results, though there are some excursions. Comparison of our recent accumulation rates with those collected along a similar route in the 1950s shows a ~10% increase in accumulation rates over the past 52 years along most of the traverse route. This implies that the increased water vapor capacity of warmer air is increasing accumulation in the interior of Greenland.

scholarly journals Kilimanjaro's Iconic Snows Mapped in Three Dimensions

Eos ◽  
2017 ◽  
Author(s):  
Katherine Kornei
Keyword(s):  
Ground Penetrating Radar ◽  
Three Dimensions ◽  
Ice Volume ◽  
Ice Field ◽  
Radar Measurements ◽  
Ground Penetrating

New ground-penetrating radar measurements reveal the thickness and total ice volume of the mountain's Northern Ice Field.

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