Snow accumulation and compaction derived from GPR data near Ross Island, Antarctica

N. C. Kruetzmann; W. Rack; A. J. McDonald; S. E. George

doi:10.5194/tcd-5-1-2011

Snow accumulation and compaction derived from GPR data near Ross Island, Antarctica

The Cryosphere ◽

10.5194/tc-5-391-2011 ◽

2011 ◽

Vol 5 (2) ◽

pp. 391-404 ◽

Cited By ~ 11

Author(s):

N. C. Kruetzmann ◽

W. Rack ◽

A. J. McDonald ◽

S. E. George

Keyword(s):

Ground Penetrating Radar ◽

Snow Accumulation ◽

Fourier Domain ◽

Improved Method ◽

Ice Shelf ◽

Dust Layer ◽

Direct Measurements ◽

Average Change ◽

One Year ◽

Ground Penetrating

Abstract. We present an improved method for estimating accumulation and compaction rates of dry snow in Antarctica with ground penetrating radar (GPR). Using an estimate of the emitted waveform from direct measurements, we apply deterministic deconvolution via the Fourier domain to GPR data with a nominal frequency of 500 MHz. This reveals unambiguous reflection horizons which can be observed in repeat measurements made one year apart. At two measurement sites near Scott Base, Antarctica, we extrapolate point measurements of average accumulation from snow pits and firn cores to a larger area by identifying a dateable dust layer horizon in the radargrams. Over an 800 m × 800 m area on the McMurdo Ice Shelf (77°45´ S, 167°17´ E) the average accumulation is found to be 269 ± 9 kg m−2 a−1. The accumulation over an area of 400 m × 400 m on Ross Island (77°40´ S, 167°11´ E, 350 m a.s.l.) is found to be higher (404 ± 22 kg m−2 a−1) and shows increased variability related to undulating terrain. Compaction of snow between 2 m and 13 m depth is estimated at both sites by tracking several internal reflection horizons along the radar profiles and calculating the average change in separation of horizon pairs from one year to the next. The derived compaction rates range from 7 cm m−1 at a depth of 2 m, down to no measurable compaction at 13 m depth, and are similar to published values from point measurements.

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

Journal of Glaciology ◽

10.1017/jog.2020.91 ◽

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.

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Ground-penetrating radar profiles of the McMurdo Shear Zone, Antarctica, acquired with an unmanned rover: Interpretation of crevasses, fractures, and folds within firn and marine ice

Geophysics ◽

10.1190/geo2015-0132.1 ◽

2016 ◽

Vol 81 (1) ◽

pp. WA21-WA34 ◽

Cited By ~ 9

Author(s):

Steven A. Arcone ◽

James H. Lever ◽

Laura E. Ray ◽

Benjamin S. Walker ◽

Gordon Hamilton ◽

...

Keyword(s):

Shear Zone ◽

Ground Penetrating Radar ◽

Ice Accretion ◽

Ice Shelf ◽

Ice Flow ◽

Ross Ice Shelf ◽

Robotic Vehicle ◽

Ground Penetrating ◽

Depth Ranges ◽

Radar Antennas

The crevassed firn of the McMurdo shear zone (SZ) within the Ross Ice Shelf may also contain crevasses deep within its meteoric and marine ice, but the surface crevassing prevents ordinary vehicle access to investigate its structure geophysically. We used a lightweight robotic vehicle to tow 200- and 400-MHz ground-penetrating radar antennas simultaneously along 100 parallel transects over a [Formula: see text] grid spanning the SZ width. Transects were generally orthogonal to the ice flow. Total firn and meteoric ice thickness was approximately 160 m. Firn crevasses profiled at 400 MHz were up to 16 m wide, under snow bridges up to 10 m thick, and with strikes near 35°–40° to the transect direction. From the top down, 200-MHz profiles revealed firn diffractions originating to a depth of approximately 40 m, no discernible structure within the meteoric ice, a discontinuous transitional horizon, and at least 20 m of stratified marine ice; 28–31 m of freeboard found more marine ice exists. Based on 10 consecutive transects covering approximately [Formula: see text], we preliminarily interpreted the transitional horizon to be a thin saline layer, and marine ice hyperbolic diffractions and reflections to be responses to localized fractures, and crevasses filled with unstratified marine ice, all at strikes from 27° to 50°. We preliminarily interpreted off-nadir, marine ice horizons to be responses to linear and folded faults, similar to some in firn. The coinciding and synchronously folded areas of fractured firn and marine ice suggested that the visibly unstructured meteoric ice beneath our grid was also fractured, but either never crevassed, crevassed and sutured without marine ice inclusions, or that any ice containing crevasses might have eroded before marine ice accretion. We will test these interpretations with analysis of all transects and by extending our grid and increasing our depth ranges.

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Estimating snow water equivalent over long mountain transects using snowmobile-mounted ground-penetrating radar

Geophysics ◽

10.1190/geo2015-0121.1 ◽

2016 ◽

Vol 81 (1) ◽

pp. WA183-WA193 ◽

Cited By ~ 9

Author(s):

W. Steven Holbrook ◽

Scott N. Miller ◽

Matthew A. Provart

Keyword(s):

Ground Penetrating Radar ◽

Snow Water Equivalent ◽

Ground Surface ◽

Snow Accumulation ◽

Accurate Estimation ◽

Snow Density ◽

Snow Stratigraphy ◽

Flood Estimation ◽

Snow Water ◽

Ground Penetrating

The water balance in alpine watersheds is dominated by snowmelt, which provides infiltration, recharges aquifers, controls peak runoff, and is responsible for most of the annual water flow downstream. Accurate estimation of snow water equivalent (SWE) is necessary for runoff and flood estimation, but acquiring enough measurements is challenging due to the variability of snow accumulation, ablation, and redistribution at a range of scales in mountainous terrain. We have developed a method for imaging snow stratigraphy and estimating SWE over large distances from a ground-penetrating radar (GPR) system mounted on a snowmobile. We mounted commercial GPR systems (500 and 800 MHz) to the front of the snowmobile to provide maximum mobility and ensure that measurements were taken on pristine snow. Images showed detailed snow stratigraphy down to the ground surface over snow depths up to at least 8 m, enabling the elucidation of snow accumulation and redistribution processes. We estimated snow density (and thus SWE, assuming no liquid water) by measuring radar velocity of the snowpack through migration focusing analysis. Results from the Medicine Bow Mountains of southeast Wyoming showed that estimates of snow density from GPR ([Formula: see text]) were in good agreement with those from coincident snow cores ([Formula: see text]). Using this method, snow thickness, snow density, and SWE can be measured over large areas solely from rapidly acquired common-offset GPR profiles, without the need for common-midpoint acquisition or snow cores.

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Helicopter-borne ground-penetrating radar investigations on temperate alpine glaciers: A comparison of different systems and their abilities for bedrock mapping

Geophysics ◽

10.1190/geo2015-0144.1 ◽

2016 ◽

Vol 81 (1) ◽

pp. WA119-WA129 ◽

Cited By ~ 24

Author(s):

Anja Rutishauser ◽

Hansruedi Maurer ◽

Andreas Bauder

Keyword(s):

Ground Penetrating Radar ◽

Low Frequency ◽

Large Data ◽

Internal Reflection ◽

Swiss Alps ◽

Reflection Band ◽

Data Set ◽

Investigation Area ◽

Attractive Option ◽

Ground Penetrating

On the basis of a large data set, comprising approximately 1200 km of profile lines acquired with different helicopter-borne ground-penetrating radar (GPR) systems over temperate glaciers in the western Swiss Alps, we have analyzed the possibilities and limitations of using helicopter-borne GPR surveying to map the ice-bedrock interface. We have considered data from three different acquisition systems including (1) a low-frequency pulsed system hanging below the helicopter (BGR), (2) a stepped frequency system hanging below the helicopter (Radar Systemtechnik GmbH [RST]), and (3) a commercial system mounted directly on the helicopter skids (Geophysical Survey Systems Incorporated [GSSI]). The systems showed considerable differences in their performance. The best results were achieved with the BGR system. On average, the RST and GSSI systems yielded comparable results, but we observed significant site-specific differences. A comparison with ground-based GPR data found that the quality of helicopter-borne data is inferior, but the compelling advantages of airborne surveying still make helicopter-borne data acquisition an attractive option. Statistical analyses concerning the bedrock detectability revealed not only large differences between the different acquisition systems but also between different regions within our investigation area. The percentage of bedrock reflections identified (with respect to the overall profile length within a particular region) varied from 11.7% to 68.9%. Obvious factors for missing the bedrock reflections included large bedrock depths and steeply dipping bedrock interfaces, but we also observed that internal features within the ice body may obscure bedrock reflections. In particular, we identified a conspicuous “internal reflection band” in many profiles acquired with the GSSI system. We attribute this feature to abrupt changes of the water content within the ice, but more research is required for a better understanding of the nature of this internal reflection band.

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Southeast Greenland high accumulation rates derived from firn cores and ground-penetrating radar

Annals of Glaciology ◽

10.3189/2013aog63a358 ◽

2013 ◽

Vol 54 (63) ◽

pp. 322-332 ◽

Cited By ~ 35

Author(s):

Clément Miège ◽

Richard R. Forster ◽

Jason E. Box ◽

Evan W. Burgess ◽

Joseph R. McConnell ◽

...

Keyword(s):

Ground Penetrating Radar ◽

Climate Model ◽

Regional Climate ◽

Elevation Gradient ◽

Greenland Ice Sheet ◽

Snow Accumulation ◽

Internal Layers ◽

Accumulation Rates ◽

High Accumulation ◽

Ground Penetrating

AbstractDespite containing only 14% of the Greenland ice sheet by area, the southeastern sector has the highest accumulation rates, and hence receives ∼30% of the total snow accumulation. We present accumulation rates obtained during our 2010 Arctic Circle Traverse derived from three 50 m firn cores dated using geochemical analysis. We tracked continuous internal reflection horizons between the firn cores using a 400 MHz ground-penetrating radar (GPR). GPR data combined with depth-age scales from the firn cores provide accumulation rates along a 70 km transect. We followed an elevation gradient from ∼2350 to ∼1830m to understand how progressive surface melt may affect the ability to chemically date the firn cores and trace the internal layers with GPR. From the firn cores, we find a 52% (∼0.43 m w.e. a-1) increase in average snow accumulation and greater interannual variability at the lower site than the upper site. The GPR profiling reveals that accumulation rates are influenced by topographic undulations on the surface, with up to 23% variability over 7 km. These measurements confirm the presence of high accumulation rates in the southeast as predicted by the calibrated regional climate model Polar MM5.

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Using ground-penetrating radar to image previous years’ summer surfaces for mass-balance measurements

Annals of Glaciology ◽

10.3189/s0260305500012441 ◽

1997 ◽

Vol 24 ◽

pp. 355-360 ◽

Cited By ~ 9

Author(s):

Jack Kohler ◽

John Moore ◽

Mike Kennett ◽

Rune Engeset ◽

Hallgeir Elvehøy

Keyword(s):

Dielectric Properties ◽

Mass Balance ◽

Ground Penetrating Radar ◽

Radar Data ◽

Snow Accumulation ◽

Ice Surface ◽

Winter Snow ◽

Depth Scale ◽

Ground Penetrating ◽

Previous Summer

In traditional mass-balance measurements one estimates winter snow accumulation by identifying the depth to the previous summer’s snow or ice surface using a snow probe. This is labor-intensive and unreliable for inhomogeneous summer surfaces. Another method is to image internal reflection horizons using a ground-penetrating radar (GPR), which has advantages in speed and areal coverage over traditional probing. However, to obtain quantitative mass-balance measurements from GPR images one needs to convert the time scale to a depth scale, not a straightforward problem. We compare a GPR section with dielectric profiles and visual stratigraphy of three snow cores, manual probings, and previous mass-balance measurements. We relate changes in snow-core dielectric properties to changes in density and to the travel times of reflecting horizons in the GPR section, and correlate some of these reflecting horizons with previous summer surfaces. We conclude that GPR can be used as a complementary tool in mass-balance measurements, giving a wide areal survey of winter accumulation and net balance for preceding years. However, proper calibration is essential for identifying specific surfaces in the radar data.

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Using ground-penetrating radar to image previous years’ summer surfaces for mass-balance measurements

Annals of Glaciology ◽

10.1017/s0260305500012441 ◽

1997 ◽

Vol 24 ◽

pp. 355-360 ◽

Cited By ~ 31

Author(s):

Jack Kohler ◽

John Moore ◽

Mike Kennett ◽

Rune Engeset ◽

Hallgeir Elvehøy

Keyword(s):

Dielectric Properties ◽

Mass Balance ◽

Ground Penetrating Radar ◽

Radar Data ◽

Snow Accumulation ◽

Ice Surface ◽

Winter Snow ◽

Depth Scale ◽

Ground Penetrating ◽

Previous Summer

In traditional mass-balance measurements one estimates winter snow accumulation by identifying the depth to the previous summer’s snow or ice surface using a snow probe. This is labor-intensive and unreliable for inhomogeneous summer surfaces. Another method is to image internal reflection horizons using a ground-penetrating radar (GPR), which has advantages in speed and areal coverage over traditional probing. However, to obtain quantitative mass-balance measurements from GPR images one needs to convert the time scale to a depth scale, not a straightforward problem. We compare a GPR section with dielectric profiles and visual stratigraphy of three snow cores, manual probings, and previous mass-balance measurements. We relate changes in snow-core dielectric properties to changes in density and to the travel times of reflecting horizons in the GPR section, and correlate some of these reflecting horizons with previous summer surfaces. We conclude that GPR can be used as a complementary tool in mass-balance measurements, giving a wide areal survey of winter accumulation and net balance for preceding years. However, proper calibration is essential for identifying specific surfaces in the radar data.

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DETECTION OF ROAD CAVITIES IN URBAN CITIES BY 3D GROUND PENETRATING RADAR

Geophysics ◽

10.1190/geo2020-0384.1 ◽

2021 ◽

pp. 1-44

Author(s):

Hai Liu ◽

Zhenshi Shi ◽

Jianhui Li ◽

Chao Liu ◽

Xu Meng ◽

...

Keyword(s):

Traffic Safety ◽

Antenna Arrays ◽

Ground Penetrating Radar ◽

Data Interpretation ◽

Cavity Depth ◽

Near Surface ◽

Horizontal Size ◽

3D Gpr ◽

One Year ◽

Ground Penetrating

Cavities under urban roads have increasingly become a great threat to the traffic safety in many cities. As a quick, effective, and high-resolution geophysical method, ground penetrating radar (GPR) has been widely used to detect and image near-surface objects. However, the interpretation of field GPR data is still challenging. For example, it is hard to distinguish reflections caused by road cavities or other urban utilities by a conventional 2D GPR survey. The superiority of 3D GPR in data interpretation is demonstrated by a laboratory experiment. Two pipes and a glass-made cavity buried in a sandpit show similar hyperbolic reflections in the 2D GPR profiles, and are hard to be discriminated. In contrast, their geometric shapes and dimensions are readily identified in the 3D image reconstructed from the synthetic 3D GPR dataset. Thus, a car-mounted 3D GPR system with two antenna arrays oriented in different polarization directions is developed, and has detected over 100 cavities in three Chinese cities over the past one year. The field data of two of the cavities are presented. As a result, the cavity depth, horizontal size and height can be accurately estimated from the 3D GPR dataset. Both laboratory and field experimental results indicate that 3D GPR possesses a great potential in detection and recognition of road cavities and utilities in the complicated urban environment.

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Interannual snow accumulation variability on glaciers derived from repeat, spatially extensive ground-penetrating radar surveys

The Cryosphere ◽

10.5194/tc-12-3617-2018 ◽

2018 ◽

Vol 12 (11) ◽

pp. 3617-3633 ◽

Cited By ~ 8

Author(s):

Daniel McGrath ◽

Louis Sass ◽

Shad O'Neel ◽

Chris McNeil ◽

Salvatore G. Candela ◽

...

Keyword(s):

Spatial Pattern ◽

Mass Balance ◽

Interannual Variability ◽

Ground Penetrating Radar ◽

Statistical Models ◽

Snow Accumulation ◽

Average Difference ◽

Elevation Gradients ◽

Small Component ◽

Ground Penetrating

Abstract. There is significant uncertainty regarding the spatiotemporal distribution of seasonal snow on glaciers, despite being a fundamental component of glacier mass balance. To address this knowledge gap, we collected repeat, spatially extensive high-frequency ground-penetrating radar (GPR) observations on two glaciers in Alaska during the spring of 5 consecutive years. GPR measurements showed steep snow water equivalent (SWE) elevation gradients at both sites; continental Gulkana Glacier's SWE gradient averaged 115 mm 100 m−1 and maritime Wolverine Glacier's gradient averaged 440 mm 100 m−1 (over > 1000 m). We extrapolated GPR point observations across the glacier surface using terrain parameters derived from digital elevation models as predictor variables in two statistical models (stepwise multivariable linear regression and regression trees). Elevation and proxies for wind redistribution had the greatest explanatory power, and exhibited relatively time-constant coefficients over the study period. Both statistical models yielded comparable estimates of glacier-wide average SWE (1 % average difference at Gulkana, 4 % average difference at Wolverine), although the spatial distributions produced by the models diverged in unsampled regions of the glacier, particularly at Wolverine. In total, six different methods for estimating the glacier-wide winter balance average agreed within ±11 %. We assessed interannual variability in the spatial pattern of snow accumulation predicted by the statistical models using two quantitative metrics. Both glaciers exhibited a high degree of temporal stability, with ∼85 % of the glacier area experiencing less than 25 % normalized absolute variability over this 5-year interval. We found SWE at a sparse network (3 stakes per glacier) of long-term glaciological stake sites to be highly correlated with the GPR-derived glacier-wide average. We estimate that interannual variability in the spatial pattern of winter SWE accumulation is only a small component (4 %–10 % of glacier-wide average) of the total mass balance uncertainty and thus, our findings support the concept that sparse stake networks effectively measure interannual variability in winter balance on glaciers, rather than some temporally varying spatial pattern of snow accumulation.

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