Nondestructive, three‐dimensional density measurements of ice core samples by X ray computed tomography

Κawamura, Toshiyuki

doi:10.1029/jb095ib08p12407

Cited by 28 publications

(19 citation statements)

References 11 publications

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“…quartz, topaz, graphite, disthene have a relation between IT and density close to relation (1) (Boespflug et al, 1994). It is preferable to use the IT as unit; however, certain authors such as Wellington and Vinegar (1987) and Kawamura (1990) use relation (1) to connect IT and samples density. The studied sediments present a percentage of organic matter lower than 5% and the same chemical composition, so it will be considered that the density is the prevalent factor of the IT variation.…”

Section: Methodsmentioning

confidence: 95%

Resuspension potential of surficial sediments in Saguenay Fjord (Québec, Canada)

et al. 2006

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Section: Methodsmentioning

confidence: 95%

Resuspension potential of surficial sediments in Saguenay Fjord (Québec, Canada)

et al. 2006

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“…However, no results are reported for densities below 460 kg m −3 . Kawamura (1990) reported good agreement between CT and the hydrostatical method to determine the density of ice cores. Hawley et al (2008) compared neutron probing, dielectric profiling, optical stratigraphy, and gravimetric measurements on an 11 m firn and ice core from Kongsvegen, Svalbard.…”

Section: Proksch Et Al: Snow Densitymentioning

confidence: 99%

Intercomparison of snow density measurements: bias, precision, and vertical resolution

Proksch

Rutter

Fierz³

et al. 2016

The Cryosphere

105

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Abstract. Density is a fundamental property of porous media such as snow. A wide range of snow properties and physical processes are linked to density, but few studies have addressed the uncertainty in snow density measurements. No study has yet quantitatively considered the recent advances in snow measurement methods such as micro-computed tomography (µCT) in alpine snow. During the MicroSnow Davos 2014 workshop, different approaches to measure snow density were applied in a controlled laboratory environment and in the field. Overall, the agreement between µCT and gravimetric methods (density cutters) was 5 to 9 %, with a bias of −5 to 2 %, expressed as percentage of the mean µCT density. In the field, density cutters overestimate (1 to 6 %) densities below and underestimate (1 to 6 %) densities above a threshold between 296 to 350 kg m −3 , dependent on cutter type. Using the mean density per layer of all measurement methods applied in the field (µCT, box, wedge, and cylinder cutters) and ignoring ice layers, the variation between the methods was 2 to 5 % with a bias of −1 to 1 %. In general, our result suggests that snow densities measured by different methods agree within 9 %. However, the density profiles resolved by the measurement methods differed considerably. In particular, the millimeter-scale density variations revealed by the high-resolution µCT contrasted the thick layers with sharp boundaries introduced by the observer. In this respect, the unresolved variation, i.e., the density variation within a layer which is lost by lower resolution sampling or layer aggregation, is critical when snow density measurements are used in numerical simulations.

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“…Density profiles are most reliably retrieved from ice/firn cores either by measuring discrete samples gravimetrically, or by using continuous dielectric profiling (Wilhelms et al, 1998) or X-ray tomography (Kawamura, 1990;Freitag et al, 2013a). Techniques such as gamma-, neutron-, laser-, or optical-scattering (Hubbard et al, 2013, and references therein) circumnavigate the labor-intensive retrieval of an ice core and only require a borehole, which can rapidly be drilled using hot water.…”

Section: R Drews Et Al: Density From Wide-angle Radarmentioning

confidence: 99%

Constraining variable density of ice shelves using wide-angle radar measurements

Drews

Brown²,

Matsuoka

et al. 2016

The Cryosphere

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Abstract. The thickness of ice shelves, a basic parameter for mass balance estimates, is typically inferred using hydrostatic equilibrium, for which knowledge of the depthaveraged density is essential. The densification from snow to ice depends on a number of local factors (e.g., temperature and surface mass balance) causing spatial and temporal variations in density-depth profiles. However, direct measurements of firn density are sparse, requiring substantial logistical effort. Here, we infer density from radio-wave propagation speed using ground-based wide-angle radar data sets (10 MHz) collected at five sites on Roi Baudouin Ice Shelf (RBIS), Dronning Maud Land, Antarctica. We reconstruct depth to internal reflectors, local ice thickness, and firn-air content using a novel algorithm that includes traveltime inversion and ray tracing with a prescribed shape of the depthdensity relationship. For the particular case of an ice-shelf channel, where ice thickness and surface slope change substantially over a few kilometers, the radar data suggest that firn inside the channel is about 5 % denser than outside the channel. Although this density difference is at the detection limit of the radar, it is consistent with a similar density anomaly reconstructed from optical televiewing, which reveals that the firn inside the channel is 4.7 % denser than that outside the channel. Hydrostatic ice thickness calculations used for determining basal melt rates should account for the denser firn in ice-shelf channels. The radar method presented here is robust and can easily be adapted to different radar frequencies and data-acquisition geometries.

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Nondestructive, three‐dimensional density measurements of ice core samples by X ray computed tomography

Cited by 28 publications

References 11 publications

Resuspension potential of surficial sediments in Saguenay Fjord (Québec, Canada)

Resuspension potential of surficial sediments in Saguenay Fjord (Québec, Canada)

Intercomparison of snow density measurements: bias, precision, and vertical resolution

Constraining variable density of ice shelves using wide-angle radar measurements

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