An operational version of avalanche forecasting using the nearest neighbours method was given to the Parsenndienst, the safety service in the ski area of the Parsenn region. They have tested this NXD method through two winters and have now decided to acquire their own computer with a mass storage unit in order to run the programme. The forecasting is being run by the patrolmen themselves, including the input of weather and snow data, and they also update the file of avalanche and blasting activities with the details of operations, as required for ammunition accountancy. The nearest neighbours method provides the patrolmen with a list of the avalanches that have occurred on the 10 d in the past 20 years most similar to the day being considered. These data represent the nearest neighbours of the method's name. The men are able to interpret the list correctly without any need of instruction, and rely on getting information from it which will help them to decide when and where to use (or not to use) explosives. The method of interpretation of the information supplied is illustrated by way of four specific examples.

Results of wind-tunnel investigations of the propagation of air within snow showed that the process responsible for causing horizontal air flux in the pore space of snow was not necessarily related to specific surface topography. The reasons for this flux formation are: (i) the near-surface wind characteristics, such as the frequency of the pressure variation related to the turbulent character of the near-surface wind; (ii) the structure of the near-surface snow, responsible for the air exchange between the atmosphere and the pore space; and (iii) the temperature difference between the snow and the atmosphere, forming the air-density difference which augments or decreases the air exchange. This paper summarizes the experimentally observed effects that the wind and the air flux generated in the pore space had on snow. These included isothermal temperature distributions throughout the artificial snow cover, snow-density change and snow recrystallization.

The ice cap on Berkner Island is grounded on bedrock within the Filchner-Ronne Ice Shelf and is, therefore, expected to be a well-suited place to retrieve long-term ice-core records reflecting the environmental situation of the Weddell Sea region. Shallow firn cores were drilled to 11 m at the two main summits of Berkner Island and analysed in high depth resolution for electrical d.c. conductivity(ECM), stable isotopes, chloride, sulphate, nitrate and methane-sulphonate (MSA).From the annual layering of δD and non-sea-salt (nss) sulphate, a mean annual snow accumulation of 26.6 cm water at the north dome and 17.4cm water at the south domeare obtained. As a result of ineffective wind scouring indicated by a relatively lownear-surface snow density, regular annual cycles are found for all species at least in the upper 4-5 m. Post-depositional changes are responsible for a substantial decrease o[the seasonal δD and nitrate amplitude as well as for considerable migration of the MSA signal operating below a depth of 3-4 m. The mean chemical and isotopic firn properties at the south dome correspond to the situation on the Filchner-Ronne Ice Shelf at a comparable distance to the coast, whereas the north dome is found to be much more influenced by maritime air masses. Persistent high sea-salt levels in winter snow at Berkner Island heavily obscure the determination of nss sulphate probably due to sulphate fractionation in the Antarctic sea-salt aerosol. Estimated time-scale spredict ages at 400 m depth to be ~2000 years for the north and ~3000 years for the south dome. Pleistocene ice is expected in the bottom 200 and 300 m, respectively.

Thrust-block naled in front of Kuannersuit Glacier, West Greenland, appears to have formed during the termination of a terrestrial surge event by a combination of enhanced winter runoff, rapid advance of the glacier terminus, and proglacial stress release by thrusting and stacking of naled blocks. This process is equivalent to the formation of thrust-block moraines. The thrust-block naled consists of at least seven thrust sheets, which are characterized by stratified ice with beds composed of a lower debris-rich lamina, an intermediate dispersed lamina and a top clean-ice lamina, and underlain by frozen outwash deposits. The thrust-block naled differs from basal stratified ice in the absence of internal deformation structures, a relatively low debris concentration, a clay-rich particle-size distribution and a preferential sorting of lighter minerals. The oxygen isotope composition of the thrust-block naled is indistinguishable from δ18O values from meteoric glacier ice and bulk meltwater, but different from basal stratified ice facies. The d–δD relationship indicates that thrust-block naled has been formed by freezing of successive thin layers of bulk waters with variable isotopic composition, whereas basal stratified ice has developed in a subglacial environment with regelation. This work shows that the association between proglacial naled and rapidly advancing glaciers may have significant consequences for the proglacial geomorphology and the interpretation of basal ice layers.

The replicate ice-coring system was developed by Ice Drilling Design and Operations (IDDO) for the US National Science Foundation. The design of the system leverages the existing infrastructure of the deep ice-sheet coring (DISC) drill to create a steerable drill capable of recovering replicate core at any targeted depth in an existing borehole. Critical requirements of the system include: collecting up to 400 m of core from the high side of an open hole; maintaining access to the entire borehole for logging tools; collecting up to four cores at a single depth; and operating to a depth of 4000m at −55°C and 34 MPa. The system was developed and tested from 2010 through 2012 and integrates several new mechanical subsystems, including two electromechanical actuators capable of pushing the sonde to any targeted azimuth, new reduced diameter core and screen barrels made from off-the-shelf casing tube, and new cutter heads optimized for the multiple stages of the replicate coring procedure. The system was successfully deployed at West Antarctic Ice Sheet (WAIS) Divide in the 2012/13 field season, recovering 285 m of core from five intentional deviations at four target depths.

This paper analyzes the effect of forest canopy on snow water equivalent during two consecutive snow seasons in a mixed beech–fir stand in the Pyrenees. The results confirm that the forest canopy is a dominant influence on snowpack distribution during the accumulation and melting periods. In general, a noticeable decrease in snow water equivalent and an increase in variability among observations are detected with increasing density of the forest canopy. The influence of the forest canopy on melting rates is complex and highly dependent on the dominant climatic conditions. Similar conclusions are reached for both of the snow seasons for which measurements are available, but several differences are also recorded. This study highlights the important influence of climatic conditions observed during the snow season on the relationship between stand characteristics and snowpack dynamics.

Stationary ice-penetrating radar (sIPR) systems can be used to monitor temporal changes in electromagnetically sensitive properties of glaciers and ice sheets. We describe a system intended for autonomous operation in remote glacial environments, and document its performance during deployments in cold and temperate settings. The design is patterned after an existing impulse radar system, with the addition of a fibre-optic link and timing module to control transmitter pulses, a micro-UPS (uninterruptable power supply) to prevent uncontrolled system shutdown and a customized satellite telemetry scheme. Various implementations of the sIPR were deployed on the Kaskawulsh Glacier near an ice-marginal lake in Yukon, Canada, for 44–77 days in summers 2014, 2015 and 2017. Pronounced perturbations to englacial radiostratigraphy were observed commensurate with lake filling and drainage, and are interpreted as changes in englacial water storage. Another sIPR was deployed in 2015–2016 on ice island PII-A-1-f, which originated from the Petermann Glacier in northwest Greenland. This system operated autonomously for almost a year during which changes in thickness of the ice column were clearly detected.

Determining whether increasing temperature or precipitation will dominate the cryospheric response to climate change is key to forecasting future sea-level rise. The volume of ice contained in the ice caps and glaciers of the Arctic archipelago of Svalbard is small compared with that of the Greenland or Antarctic ice sheets, but is likely to be affected much more rapidly in the short term by climate change. This study investigates the mass balance of Austfonna, Svalbard’s largest ice cap. Equilibrium-line fluxes for the whole ice cap, and for individual drainage basins, were estimated by combining surface velocities measured using satellite radar interferometry with ice thicknesses derived from radio-echo sounding. These fluxes were compared with balance fluxes to reveal that during the 1990s the total mass balance of the accumulation zone was (5.6±2.0)×108m3 a–1. Three basins in the quiescent phase of their surge cycles contributed 75% of this accumulation. The remaining volume may be attributable either to as yet unidentified surge-type glaciers, or to increased precipitation. This result emphasizes the importance of considering the surge dynamics of glaciers when attempting to draw any conclusions on climate change based on snapshot observations of the cryosphere.

An ice-flow model is used to simulate the front variations of the Pasterze glacier, Austria. The model deals explicitly with the ice flux from sub-streams and tributaries to the main ice stream. The dynamic calibration method adopted successfully calibrates the ice-flow model under a non-steady-state condition. Despite the complexity of the glacier geometry, the ice dynamics of the Pasterze are adequately simulated.

Results of the sensitivity experiments suggest that the Pasterze glacier has been in a non-steady state most of the time and has a response time of 34–50 years.

Projections of the behaviour of the Pasterze in the next 100 years are made under various climate scenarios. Results suggest that the Pasterze will undergo a substantial retreat if there is future warming. The glacier is likely to retreat 2–5 km by the year 2100. The ice volume could be reduced by 24–63% by the end of the 21st century.

An ice-shelf model which features efficient numerical techniques is developed to determine the back-force exerted by sides and pinning points, such as islands of an embayed ice shelf. The model is applied to three ideal geometries and shows that the restraint exerted by a small island, even far downstream from the grounding line, can represent about one-half of the total restraint due to the embayment. Our results are further interpreted to suggest several criteria useful for testing any ice-shelf model.

Methanesulphonic acid (MSA) is an important trace-ion constituent in ice cores, with connections to biological activity and sea-ice distribution. Post-depositional movement of MSA has been documented in firn, and this study investigates movement in solid ice by measuring variations in MSA distribution across several horizontal sections from an ice core after 14.5 years storage. The core used is from below the bubble close-off depth at Dome Summit South, Law Dome, East Antarctica. MSA concentration was studied at 3 and 0.5 cm resolution across the core widths. Its distribution was uniform through the core centres, but the outer 3 cm showed gradients in concentrations down to less than half of the central value at the core edge. This effect is consistent with diffusion to the surrounding air during its 14.5 year storage. The diffusion coefficient is calculated to be 2 ×10–13 m2 s–1, and the implications for the diffusion mechanism are discussed.

The cone penetration test has been successfully used to classify soil for ∼100 years. However, it has received only limited contemporary use in frozen geomaterials. The historical and contemporary use of the cone penetration test in various frozen geomaterials is considered here and contemporary data from recent work in polar snow are examined. It is probable that many material physical properties (e.g. density, strength and microstructure) can be obtained directly from cone penetration testing. It appears under-utilized as a contemporary scientific and engineering investigative tool in frozen geomaterials.

The reflection and transmission of ice-coupled waves under a sea-ice sheet is re-examined in this work. Recent theory can account for inhomogeneities in ice sheets such as the sails of pressure ridges and cracks or leads, but has only examined small numbers of features. Here the scattering coefficients can be obtained for an ice sheet containing a region of arbitrarily varying thickness that more closely approximates a real ice sheet and, consequently, models wave scattering more effectively. We explore the consequences of inverting ridge keels, placing the mass above the ice sheet as a technique by which the keel can be partially accounted for. It is found that the ridge sails themselves can reasonably be neglected. Upward-looking submarine sonar data are used to demonstrate the use of the model, noting that there are choices as to how to interpret such data. The model is tested to establish its sensitivity to these choices.

Statistics of Arctic Sea-ice Surface roughness have been investigated in order to improve classification of ice-thickness regimes. The data consist of Surface roughness and thickness profiles, acquired Simultaneously by helicopter-borne laser altimetry and electromagnetic induction Sounding. Five thickness classes were identified using the modal thickness as a criterion. For each class, the Statistical properties of the Surface roughness profiles were analyzed. A classification algorithm was designed, which assigns profiles to the thickness classes on the basis of a Set of Selected Statistical roughness parameters. The algorithm was applied to profiles of different lengths. Best results were obtained for 2 km long profiles, for which it was possible to discriminate well between thick first-year and multi-year ice, and to distinguish these classes from thinner ice. The classification rule was tested on data obtained under winter and Summer conditions. The results Suggest that Statistical Surface roughness properties are different for thinner and thicker ice classes. However, individual thin-ice classes cannot be discriminated on the basis of the Selected roughness parameters.

An energy-balance model is used to calculate mass balance and equilibrium-line altitudes (ELAs) on two northwest Spitsbergen glaciers, Austre Brøggerbreen and Midre Lovénbreen, whose mass balances are at present negative, and for which greater than 20 year records of mass-balance data are available. The model takes meteorological data, ice-mass area distribution with altitude, and solar radiation as inputs. Modelling uses mean daily meteorological data from a nearby weather station, adjusted for altitude. Average net balances modelled for 1980–89 using models tuned to the decade’s average were –0.44 and –0.47 m w.e. for Lovénbreen and Brøggerbreen, respectively, compared with the measured averages of –0.27 and –0.36 m. Sensitivity tests on glacier response to greenhouse warming predict a net balance change of –0.61 m year–1 per °C temperature rise relative to today, and a rise in ELA of 90 m °C–1. Modelling of Little lee Age conditions in Spitsbergen suggests that a 0.6°C cooling or a precipitation increase of 23% would yield zero net mass balance for Lovénbreen and that further cooling would increase net balance by 0.30 m year–1 °C–1. Set in the context of similar modelling of southern Norwegian, Alpine and Greenland ice masses, these results support the suggestion that glaciers with a maritime influence (i.e. higher accumulation) are most sensitive to climate change, implying a gradient towards decreasing sensitivity as accumulation decreases eastward and with altitude in Svalbard.

The first recordings of acoustic signals associated with avalanches go back to the 1970s when premonitory low-frequency acoustic emission was observed in the snow cover just before the setting off of natural avalanches (Sommerfeld, 1977; Sommerfeld and Gubler, 1983). Recently, it has been demonstrated that avalanches also produce strong infrasonic vibrations in air during their movement. These infrasonic vibrations propagate great distances and can follow the natural relief. It was then a question of automatically detecting this emission to monitor avalanche activity, with a view to improving forecasting and assisting in the study of certain aspects of avalanche dynamics.

With the double aim of pursuing investigations on the mechanics of the acoustic emission from avalanches and designing an automatic detection system, our laboratory has developed specific instrumentation, the essential link of which is an array of infrasonic microphones associated with a goniometer. Systematic measurements of the infrasonic emissions are being carried out, not only of the natural or released avalanches themselves but of all events with the aim of characterizing the former in relation to “infrasonic noise”.

According to the division into subareas of water-resource distribution in China, and based on the Glacier Inventory of China (GIC), China’s total glacier water storage is 5040.2 x 109m3, 33.0% of which is distributed in the southwest drainage basins and 64.1% in the northwest inland drainage basins, forming enormous solid reservoirs with plentiful freshwater storage. Glacier change in China is estimated for the periods from the Little Ice Age (LIA) maximum to about 1960 and from 1960 to 1995. The relative glacierized area loss is 23% and 8.9% respectively for maritime glaciers and 15% and 4.9% respectively for continental glaciers. The normal annual glacier meltwater runoff is estimated at 60 465 x 106m3 by the climate parameter temperature-index method, 38.7% of which is distributed in the northwest inland drainage basins, and at 61 574 x 106m3 by the glacier system temperature-index method, 41.5% of which is distributed in the northwest inland drainage basins. Simulation of glacier meltwater runoff under the temperature change ratio of 0.03 K a–1 by the glacier system model in west China between 1980 and 2000 indicates that the total glacier meltwater runoff increment is 10.8% overall, 14.3% in the inland drainage basins of northwest China and 9.0% in the outflow drainage basins of southwest China.

Radar surveys across ice sheets typically measure numerous englacial layers that can often be regarded as isochrones. Such layers are valuable for extrapolating age–depth relationships away from ice-core locations, reconstructing palaeoaccumulation variability, and investigating past ice-sheet dynamics. However, the use of englacial layers in Antarctica has been hampered by underdeveloped techniques for characterising layer continuity and geometry over large distances, with techniques developed independently and little opportunity for inter-comparison of results. In this paper, we present a methodology to assess the performance of automated layer-tracking and layer-dip-estimation algorithms through their ability to propagate a correct age–depth model. We use this to assess isochrone-tracking techniques applied to two test case datasets, selected from CreSIS MCoRDS data over Antarctica from a range of environments including low-dip, continuous layers and layers with terminations. We find that dip-estimation techniques are generally successful in tracking englacial dip but break down in the upper and lower regions of the ice sheet. The results of testing two previously published layer-tracking algorithms show that further development is required to attain a good constraint of age–depth relationships away from dated ice cores. We recommend that auto-tracking techniques focus on improved linking of picked stratigraphy across signal disruptions to enable accurate determination of the Antarctic-wide age–depth structure.

The Sea of Okhotsk is the southernmost area in the Northern Hemisphere where seasonal sea ice is produced every year. The formation of sea ice drives thermohaline circulation in the Sea of Okhotsk, and this circulation supports the high productivity in the region. However, recent reports have indicated that sea-ice production in the Sea of Okhotsk is decreasing, raising concern that the decreased sea ice will affect not only circulation but also biological productivity in the sea. To reconstruct climatic changes in the Sea of Okhotsk region, we analyzed an ice core obtained from Ichinskaya Sopka (Mount Ichinsky), Kamchatka. We assumed that the remarkable negative peaks of δD in the ice core were caused by expansion of sea ice in the Sea of Okhotsk. Melt feature percentage (MFP), which indicates summer snowmelt, showed high values in the 1950–60s and the mid-1990s–2000s. The high MFP in the 1950–60s was assumed to be caused by an increase in cyclone activity reaching Kamchatka during a negative period of the Pacific Decadal Oscillation index, and that in the 1990–2000s may reflect the increase in solar irradiation during a positive period of the summer Arctic Oscillation index.

Virkisjökull is a rapidly retreating outlet glacier draining the western flanks of Öræfajökull in SE Iceland. Since 2011 there have been continuous measurements of flow in the proglacial meltwater channel and regular campaigns to sample stable isotopes δ2H and δ18O from the river, ice, moraine springs and groundwater. The stable isotopes provide reliable end members for glacial ice and shallow groundwater. Analysis of data from 2011 to 2014 indicates that although ice and snowmelt dominate summer riverflow (mean 5.3–7.9 m3 s−1), significant flow is also observed in winter (mean 1.6–2.4 m3 s−1) due primarily to ongoing glacier icemelt. The stable isotope data demonstrate that the influence of groundwater discharge from moraines and the sandur aquifer increases during winter and forms a small (15–20%) consistent source of baseflow to the river. The similarity of hydrological response across seasons reflects a highly efficient glacial drainage system, which makes use of a series of permanent englacial channels within active and buried ice throughout the year. The study has shown that the development of an efficient year round drainage network within the lower part of the glacier has been coincident with the stagnation and subsequent rapid retreat of the glacier.