The Temperature, Melt Water Movement and Density Increase in the Névé of an Alpine Glacier

Hughes, T. P.; Seligman, G.

doi:10.1111/j.1365-246x.1939.tb02922.x

Cited by 40 publications

(2 citation statements)

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“…These profiles are comparable to the ones from earlier studies on Grosser Aletschgletscher (e.g. Hughes and Seligman, 1939;Seligman, 1941). The variability in the density profiles is composed of the real signal and measurement uncertainties.…”

Section: Comparison With In Situ Datasupporting

confidence: 87%

“…Already in the 1940s, extensive fieldwork was performed mainly to assess the temperature structure of the glacier (e.g. Hughes and Seligman, 1939;Seligman, 1941). Since 2011, Grosser Aletschgletscher has been observed by the TanDEM-X bistatic InSAR formation and has been defined by the DLR as an Alpine super-test site for glaciological applications; about 159 experimental repeat pass scenes have been acquired over the glacier.…”

Section: Study Areamentioning

confidence: 99%

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Elevation bias due to penetration of spaceborne radar signal on Grosser Aletschgletscher, Switzerland

Bannwart,

Piermattei,

Dussaillant

et al. 2024

J. Glaciol.

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Digital elevation models (DEMs) from the spaceborne interferometric radar mission TanDEM-X hold a large potential for glacier change assessments. However, a bias is potentially introduced through the penetration of the X-band signal into snow and firn. To improve our understanding of radar penetration on glaciers, we compare DEMs derived from the almost synchronous acquisition of TanDEM-X and Pléiades optical stereo-images of Grosser Aletschgletscher in March 2021. We found that the elevation bias – averaged per elevation bin – can reach up to 4–8 m in the accumulation area, depending on post co-registration corrections. Concurrent in situ measurements (ground-penetrating radar, snow cores, snow pits) reveal that the signal is not obstructed by the last summer horizon but reaches into perennial firn. Because of volume scattering, the TanDEM-X surface is determined by the scattering phase centre and does not coincide with a specific firn layer. We show that the bias corresponds to more than half of the decadal ice loss rate. To minimize the radar penetration bias, we recommend to select DEMs from the same time of the year and over long observation periods. A correction of the radar penetration bias is recommended, especially when combining optical and TanDEM-X DEMs.

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Section: Comparison With In Situ Datasupporting

confidence: 87%

Section: Study Areamentioning

confidence: 99%

Elevation bias due to penetration of spaceborne radar signal on Grosser Aletschgletscher, Switzerland

Bannwart,

Piermattei,

Dussaillant

et al. 2024

J. Glaciol.

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Radar investigations of melt pathways in a natural snowpack

1999

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Effect of snow structure on water flow and solute transport

Waldner

Schneebeli

Schultze-Zimmermann³

et al. 2004

Hydrological Processes

116

139

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Abstract:Water flow through a melting snow pack modifies its structure and stability and affects the release of water and nutrients into soils and surface waters. Field and laboratory observations indicate a large spatial variability on various scales of the liquid water content and flow, a dominant system feature currently not included in numerical models. We investigated experimentally water and dye tracer movement through microstructurally different snow pack horizons and the persistence of preferential flow paths. Naturally rounded snow of varying grain size was artificially packed to obtain well known conditions by sieving it into rectangular bins. Surface melt was induced with infrared lamps. The flow paths were visualized with tracers and liquid water content was monitored with time domain reflectometry probes. Vertical cuts through the snow pack were imaged. The dye tracer patterns allowed the two flow regimes 'matrix flow' and 'preferential flow' to be distinguished. Matrix flow is apparently dominated by film and capillary flow in the unsaturated snow matrix. The capillary barrier effect at a boundary between a fine over a coarse textured layer on matrix flow in snow was confirmed. In contrast, preferential flow appears as well-defined flow fingers that advance from 0Ð1 to 1 cm s 1 . During a melt phase, the advancing flow fingers enlarge and are only partially time invariant. It remains to be shown whether the continuum concept, including the Darcy-Buckingham law is apt to describe the extremely non-linear nature of water flow and the travel time of solutes in snow under conditions of melt water percolation. Probably, snow packs that include faceted crystals and large variations in bulk density, feature more pronounced capillary barriers and preferential flow triggering, but also stronger impeding of fingers by lateral dispersion. Further, triggering and persistence of preferential flow is complicated by the usually transient infiltration rate.

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The Temperature, Melt Water Movement and Density Increase in the Névé of an Alpine Glacier

Cited by 40 publications

References 0 publications

Elevation bias due to penetration of spaceborne radar signal on Grosser Aletschgletscher, Switzerland

Elevation bias due to penetration of spaceborne radar signal on Grosser Aletschgletscher, Switzerland

Radar investigations of melt pathways in a natural snowpack

Effect of snow structure on water flow and solute transport

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