Casting snow is necessary to prevent metamorphism and deformation prior to X-ray micro-computed tomography (μCT) imaging. Current methods are insufficient for large-scale field sampling of snow due to safety considerations associated with the casting medium and/or lengthy sample preparation times. Here, a casting method using contrast-enhanced diethylphthalate (DEP) for μCT of snow is presented. The X-ray contrast of DEP is enhanced with barium titanate nanoparticles (BaTiO3) and iodine (I2). A partially unsupervised, three-phase segmentation method utilizing traditional Gaussian smoothing followed by a three-step process to address transition voxels is also presented. Synthetic images derived from real snow samples are used to evaluate the segmentation method with various configurations of trapped air bubbles. Real snow samples spanning a range of specific surface areas (SSAs) (8–28 m2 kg−1) and densities (135–463 kg m−3) are used to assess the performance of the segmentation method on real, cast samples. The method yields SSA, density and correlation length errors of less than 10% for synthetic images with air bubble surface areas less than 333 m−1 per sample volume for eight of the nine snow samples. For eight of the nine cast samples, the method yields errors of less than 10% for all three parameters.

Cryoconite holes can be important sources and stores of water and nutrients on cold and polythermal glaciers, and they provide a habitat for various forms of biota. Understanding the hydrological connectivity of cryoconite holes may be the key to understanding the transport of nutrients and biological material to the proglacial areas of such glaciers. This paper aims to characterize and explain spatial variability in the connectivity of ice-lidded cryoconite holes on a small, piedmont glacier in the McMurdo Dry Valleys through geochemical analysis of cryoconite hole waters. Solute concentrations in both surface and near-surface ice and cryoconite holes, vary greatly along the glacier centerline, and all sample types displayed similar spatial patterns of variability. Using chloride as a tracer, we estimated variations in cryoconite hole connectivity along the glacier centerline. We found that a previously used mass transfer method did not provide reliable estimates of the time period for which cryoconite hole waters had been isolated from the atmosphere. We attribute this to spatial variability in both the chloride content of the surface ice and surface ablation rates. The approach may, however, be used to qualitatively characterize spatial variations in the hydrological connectivity of the cryoconite holes. These results also suggest that ice-lidded cryoconite holes are never truly isolated from the near-surface drainage system.

This paper reports on research on the relationship between the electromagnetic scattering properties and physical properties of snow-pack. An FM-CW active microwave radar system operating in the frequency range 8-12 GHz is used to scatter electromagnetic radiation from surface and subsurface stratigraphic layers in the snow-pack. The amplitude of the scattered radiation as a function of depth in the snow-pack can be correlated with such physical characteristics as density, hardness, stratigraphy, and moisture content. A direct determination of snow-pack water equivalence can be made from these observations.

Observations on both the modern and Pleistocene snow lines were made during a journey through the Peruvian Andes. En route observations were supplemented by an evaluation of air photographs in the Servicio Aerofotográfico Nacional in Lima and a survey of the literature. The large-scale variation of the Pleistocene snow-line depression is discussed with respect to possible palaeoclimatic implications.

Hydrologic pathways beneath ice sheets and glaciers play an important role in regulating ice flow. Antarctica has experienced, and will continue to experience, changes in ice dynamics and geometry, but the associated changes in subglacial hydrology have received less attention. Here, we use the GlaDS subglacial hydrology model to examine drainage evolution beneath an idealised Antarctic glacier in response to steepening ice surface slopes, accelerating ice velocities and subglacial lake drainages. Ice surface slope changes exerted a dominant influence, redirecting basal water to different outlet locations and substantially increasing channelised discharge crossing the grounding line. Faster ice velocities had comparatively negligible effects. Subglacial lake drainage results indicated that lake refilling times play a key role in drainage system evolution, with lake flux more readily accommodated following shorter refilling times. Our findings are significant for vulnerable Antarctic regions currently experiencing dynamic thinning since subglacial water re-routing could destabilise ice shelves through enhanced sub-shelf melting, potentially hastening irreversible retreat. These changes could also affect subglacial lake activity. We, therefore, emphasise that including a nuanced and complex representation of subglacial hydrology in ice-sheet models could provide critical information on the timing and magnitude of sea-level change contributions from Antarctica.

We developed a tilt sensor for studying ice deformation and installed our tilt sensor systems in two boreholes drilled close to the shear margin of Jarvis Glacier, Alaska to obtain kinematic measurements of streaming ice. We used the collected tilt data to calculate borehole deformation by tracking the orientation of the sensors over time. The sensors' tilts generally trended down-glacier, with an element of cross-glacier flow in the borehole closer to the shear margin. We also evaluated our results against flow dynamic parameters derived from Glen's exponential flow law and explored the parameter space of the stress exponent n and enhancement factor E. Comparison with values from ice deformation experiments shows that the ice on Jarvis is characterized by higher n values than that is expected in regions of low stress, particularly at the shear margin (~3.4). The higher n values could be attributed to the observed high total strains coupled with potential dynamic recrystallization, causing anisotropic development and consequently sped up ice flow. Jarvis' n values place the creep regime of the ice between basal slip and dislocation creep. Tuning E towards a theoretical upper limit of 10 for anisotropic ice with single-maximum fabric reduces the n values by 0.2.

Shortly before the war this new word for the study of glaciology was coined in Central Europe. The Greek noun κρύος means “cold.” It is not clear why this word should be applied exclusively to cooled water; it could equally well be used for any cooled substance, for example carbon dioxide or ice cream.

Synchrotron-based micro-X-ray fluorescence (μXRF) equipment has been used to analyze impurities in polar ice. A customized sample holder has been developed and the μXRF equipment has been adapted with a thermal control system to keep samples unaltered during analyses. Artificial ice samples prepared from ultra-pure water were analyzed to investigate possible contamination and/or experimental artefacts. Analyses of polar ice from Antarctica (Dome C and Vostok) confirm this μXRF technique is non-destructive and sensitive. Experiments can be reproduced to confirm or refine results by focusing on interesting spots such as crystal grain boundaries or specific inclusions. Integration times and resolution can be adjusted to optimize sensitivity. Investigation of unstable particles is possible due to the short analysis time. In addition to identification of elements in impurities, μXRF is able to determine their speciations. The accuracy and reliability of the results confirm the potential of this technique for research in glaciology.

Microscopic observation of air-hydrate crystals was carried out using 34 deep ice-core samples retrieved at Vostok Station, Antarctica. Samples were obtained from depths between 1050 and 2542 m, which correspond to Wisconsin/Sangamon/Illinoian ice. It was found that the volume and number of air-hydrate varied with the climatic changes. The volume concentration of air-hydrate in the interglacial ice was about 30% larger than that in the glacial ice. In the interglacial ice, the number concentration of air-hydrate was about a half and the mean volume of air-hydrate was nearly three times larger than that in the glacial-age ice. The air-hydrate crystals were found to grow in the ice sheet, about 6.7 × 10−12 cm3 year-1, in compensation for the disappearance of smaller ones. The volume concentration of air-hydrate was related to the total gas content by a geometrical equation with a proportional parameter α. The mean value of α below 1250 m, where no air bubbles were found, was about 0.79. This coincided with an experimentally determined value of the crystalline site occupancy of the air-hydrate in a 1500 m core obtained at Dye 3, Greenland (Hondoh and others, 1990). In the depth profile of calculated α for many samples, α in the interglacial ice was about 30% smaller than that in the glacial-age ice.

This pilot study adopts a computer-assisted synoptic typing methodology to evaluate the totality of climatic influences on snow- and ice-melt dynamics within a small cirque basin in the French Pyrénées. The synoptic categories identified possess contrasting large-scale atmospheric circulation patterns and surface energy budgets which generate differential ablation responses. Continental air masses yield consistently high melt. Advection of moist maritime air also produces elevated but more variable ablation due to air-mass transitions. The two observed local valley circulation types show melt to be higher under nocturnal katabatic drainage than for anabatic wind flows associated with development of daytime ridge-top cumulus.

Pleistocene ice-sheet temperatures are reconstructed for a west-to-east transect across northern Scotland at the ice maximum using the temperature-profile model of Budd and others (1971[a]). Basal freezing is predicted for the central area of the ice sheet, and zones of basal melting on each side to the west and east. Variations in estimates of annual accumulation rate and ice thickness do not greatly alter this general pattern. However, small errors in estimating mean annual temperature at the ice edge and ice-surface temperature lapse-rate may significantly change the pattern of predicted basal temperature regimes, and basal freezing may have extended over the whole of the area considered. Zones of areal scouring occur in both the west and east of the transect but are absent from the central mountain area. Under some of the temperature conditions modelled there is a partial spatial coincidence of the areal scouring in the west with predicted areas of basal melting, but almost none in the east. Possibly this is explained because glacial erosion relates to time periods other than the ice maximum.

Observations of glacier flow and explanations of its origin started as early as the 18th century. Several mechanisms were suggested before gravity-driven viscous flow became the accepted theory of glacier flow in the 1950s, the early years of the Journal of Glaciology. Since the viscosity of ice is strongly temperature-dependent, the topic of glacier and ice-sheet dynamics became essentially a fluid-dynamical problem. The availability of growing computing power turned the field of glacier mechanics and thermodynamics into a field of numerical modelling with increasing sophistication.

Study of the waning snow-pack along the crest of the White Mountains of California and Nevada in 1970 and 1974 indicates that a significant proportion of the high-altitude snow in the range sublimates and/or evaporates shortly after melting. Qualitative and limited quantitative evidence suggest that the amount of snow thus disposed of may be as much as 50-80% of the total springtime pack. Meteorological observations in the White Mountains demonstrate that atmospheric conditions particularly favorable for effective sublimation/evaporation are common in May and June, the main ablation period in the mountains. The general lack of evidence of surficial erosion on slopes above 3 500 m, often supposed to be wide-spread and caused by so-called "snow-melt" runoff, is therefore readily explained-there is little "snow-melt" erosion simply because there is only limited snow-melt.

Recent research has highlighted the potential for high-resolution, high-density, 3D and 4D ground-penetrating radar (GPR) acquisitions on alpine glaciers. When carried out on foot, such surveys are laborious and time consuming, which limits their application to small domains of limited glaciological interest. Further, crevasses and other hazards make the data acquisition risky. To address these issues, we have developed a drone-based GPR system. The system has a payload weight of 2.2 kg and a data output rate of 14 traces per second. An 80-MHz antenna and a recording time of 2800 ns mean that depths of over 100 m can be reached in temperate ice. Differential GPS positioning assures accurate flight paths. At a speed of 4 m s−1 and height of 5 m above the glacier surface, our system can acquire over 4 line-km of GPR data in 20 min on a single set of drone batteries. After presenting the technical specifications of the system and tests required to optimize its performance, we showcase a recently acquired 3D dataset from the Otemma glacier in Switzerland, where 462 parallel GPR profiles were surveyed at a 1-m line spacing, totaling over 112 line-km of data, in only 4 days.