Uniaxial compression tests (UCT) under constant cross-head speed and simple shear tests (SST) under constant load have been carried out in a snow cave at -16°C on ice cores within at most one month of extraction from depths of 235, 504, 708, and 896 m at Dye-3, Greenland, as part of the Greenland Ice Sheet Program (GISP), in order to improve understanding of flow behavior. UCT specimens had their stress axis at 45° from the core axis and SST specimens had their shear parallel to the horizontal plane of the core, so that in both cases maximum resolved shear stress was in the horizontal plane of the ice sheet.

Fracture stresses in UCT had characteristic values for each depth corresponding to core quality. When effective strain-rate was plotted against effective shear stress on a double logarithmic plot, (1) data from the same depth fell on the same straight line for both tests, (2) for a given stress, strainrate varied with core-depth by less than half an order of magnitude, and (3) the stress exponent lay between 2 and 2.5, significantly less than the 3 to 4 reported for polycrystalline ice.

Values extrapolated from the present data agree quite well with those deduced from bore-hole tilting measurements at Byrd station, Antarctica, and Camp Century, Greenland.

Local ice strains and in situ ice stresses were simultaneously measured on the Coordinated Eastern Arctic Experiment (CEAREX). The experiment took place in the fall of 1988 and was centered about an ice-strengthened ship moored to a multi-year floe in the pack ice northeast of Spitsbergen. During the period of data collection, which extended from early October to late November, the ship and the ice surrounding it drifted from 82°40′N, 32°32′E to 78°54′N, 31°27′E.

As soon as ice temperatures were low enough to permit installation, stress sensors were placed at four sites, two sites on each of two adjacent multi-year floes. Principal stress components and the principal stress direction were determined at each sensor. At the same time, microwave transponders, capable of measuring ice deformation to accuracies better than 1 m, were positioned within 1 km of the stress sensors and provided an approximation of the local strain field.

What makes this joint dataset particularly interesting is that it includes some large ridging events and a particularly large event which terminated the experiment when the multi-year floes in the local area were broken into small fragments. A wide range of ice stresses was measured during the period. The largest compressive stresses, about 250 kPa, were measured by the near-surface sensors. Although sensors in different locations responded differently to ice movement, the large events were common to all shallow sensors.

In a static supercooled cloud dendrites hardly grow at about -15°C except at the pointed tip of a needle-like ice crystal or an isolated thin plate-like ice crystal. When ice crystals are moved slowly in a static supercooled cloud, dendrites grow at about -15° C and the α-axis growth rate increases as the velocity of the dendrites increases; at velocities higher than 20 cm/s, however, the a-axis growth rate decreases as the velocity increases due to the influence of heavy riming. The maximum a-axis growth rate in a supercooled cloud is observed at about -15°C in experiments growing ice crystals in free fall.

Measurement of wind velocity, wind direction, air temperature, precipitation and humidity were obtained at various altitudes in order to describe micrometeorological conditions on the north slope of Mount Qogir (K2). Meteorological elements were monitored above the moraine surface in the proglacial area and over the ice surface in the ablation area and snow surface in the firn area of K2 glacier. Precipitation increases quickly with altitude from the dry valley to the firn area. Relative humidity also increases with elevation. In the K2 glacier area, the highest absolute humidity occurs over the glacier tongue. The effects of melting and freezing of the surface of the glacier in the ablation area on diurnal and day-to-day changes in air temperature influence air temperature in ablation areas, decreasing diurnal range by comparison with the firn areas. On clear days, a down-valley wind blows from the firn area before sunrise and an up-valley wind after sunrise. On days with precipitation, an up-valley wind predominates in the night-time and a down-valley wind in the day-time.

A global atmosphere-ocean-sea-ice general circulation model (GCM) is used in simulations of climate with greenhouse gas concentrations and sulfate aerosols prescribed from observational data (1870−1995) and future projections (1995−2100). Simulations that include the variability in solar flux from 1870 through 1995 are also performed. The variation in solar flux of ± 2 W m−2 produces a global temperature change of ± 0.2°C in the model. The more recent simulated warming trend produced by increasing greenhouse gases exceeds this solar-flux warming, although the solar flux contributes to some of the simulated present-day warm temperatures. The future increases in greenhouse gases produce an increase in global temperature of 1.2°C over 70 years, with significant decreases in Arctic ice thickness and area. The model exhibits an atmospheric pressure mode similar to the Arctic Oscillation, with different correlation indices between the North Atlantic and North Pacific pressure anomalies.

The present and future ice conditions around 100 years from present in the Baltic Sea are examined by two 10 year integrations of an ice-ocean model. Results from atmospheric climate-model simulations constitute the atmospheric forcing, one representing present climate conditions (control simulation), and the other global warming due to CO2 doubling (scenario simulation). The present-day climatological ice conditions and the interannual variability were realistically reproduced by the ice-ocean model. The modelled range of the maximum annual ice extent in the Baltic was 190−420 × 103km2 in the control simulation and 50−270 × 103km2 in the scenario simulation. The range of the annual maximum level-ice thickness was 45−85 and 20−58 cm in the control and scenario simulations, respectively.

A collapse of the West Antarctic ice sheet due to warming by atmospheric carbon dioxide is a potential threat to mankind because low-lying land would be flooded by rising sea-level. Intervention would be possible by creating one or several artifical ice rises on the floating ice shelves surrounding the West Antarctic ice sheet. Ice rises are places where the ice shelf has run aground locally on the sea bed. Existing ice rises obstruct ice flow and are responsible for maintaining the ice sheet in its present stable condition. An artificial ice rise could be created by (1) drilling a hole through the ice shelf in a choice position such as over a sea-bed ridge, (2) pumping large volumes of sea-water from beneath the ice shelf so as to flood the surface, and (3) continuing to pump until the frozen sea-water has thickened the ice shelf by 100 m over an area of 100 km2. Approximately 1.6 × 106 kW of power would be required to accomplish the task in ten years. This would cost approximately 20 × 109 US dollars.

Sea-ice thickness distributions from 12 submarine cruises under the North Pole are used to evaluate and enhance the results of sea-ice model simulations. The sea-ice models include versions with cavitating fluid and elastic-viscous-plastic rheologies, and versions with a single thickness and with multiple (5–27) thicknesses in each gridcell. A greater portion of the interannual variance of observed mean thickness at the Pole is captured by the multiple-thickness models than by the single-thickness models, although even the highest correlations are only about 0.6. After The observed thickness distributions are used to ˚tune" the model to capture the primary mode of the distribution, the largest model-data discrepancies are in the thin-ice tail of the distribution. In a 41 year simulation ending in 1998, the model results show a pronounced decrease of mean ice thickness at the Pole around 1990; the minimum simulated thickness occurs in summer 1998. The decrease coincides with a shift of the Arctic Oscillation to its positive phase. The smallest submarine-derived mean thickness occurs in 1990, but no submarine data were available after 1992. The submarine-derived thicknesses for 1991 and 1992 are only slightly smaller than the 12–case mean.

In previous work, particle analyses of fresh snow and ice cores from Camp Century, Greenland, were conducted by transmission electron-microscopy. The particles found most frequently were silicate minerals 0.05-8 μm diameter (Kumai 1977). The mean pH of snow in Ellesmere Island (81 °N, 73°W) was 5.23 for 1954-80 (Koerner and Fisher 1982). The mean pH of snow in Hanover, NH, was 4.61 for 1972-73 and 4.48 for 1980-83. The mean pH of snow in a rural area near Fairbanks, Alaska, was 5.60 for 1972-73 (Kumai 1985).

In this paper, the results of measurement of pH, electrolytic conductivity, aerosol concentration and elemental analysis of aerosols in snow and ice cores from Greenland are described and compared with those of snow from Alaska, the Canadian Arctic and New Hampshire.

The snow samples were collected at Dye 3, Greenland, from 17 to 250 cm depth; they were deposited during snowfalls from January 1980 to spring 1983. A total of 45 snow samples was examined; the samples were each about 65 g and collected at 5 cm intervals in the snow pit. The snow and ice-core samples were melted in a microwave oven for measurements of pH and electrolytic conductivity. A pH meter (Solution Analyzer, model 4505A) was calibrated by two buffer solutions of pH 4.00 and 7.00 at 25 °C. Two instruments were used for electrolytic conductivity measurements, Solution Analyzer, model 4505A, and Conductance Bridge RCM 1581, and calibrated by a standard solution of 0.005 N KC1 (720 ± 1 (μS cm−1) at 25°C. The snow and ice melt-water samples were filtered through polycarbonate membrane filters of 0.4 μm pore diameter. Particles remaining on the filters dried in a vacuum oven at 30°C, and the aerosol concentrations measured by chemical balance. The aerosols on the filters were coated by Au and Pd vapor in a vacuum chamber, for examination by scanning electron-microscopy and energy-dispersive X-ray analysis.

Results of melted snow measurements from Greenland were as follows. The pH ranged from 4.57 to 5.01; the mean pH was 4.81 in 1981. For 1982 the pH ranged from 4.72 to 4.93; the mean was 4.81. For 1983, the pH ranged from 4.50 to 5.20; the mean was 4.85. The mean pH of all snow from Greenland was lower than that of snow in a rural area of the Alaskan and Canadian Arctic, but higher than that of snow in New Hampshire.

Electrolytic conductivity of snow from Greenland varied from 3.95 to 9.70 μS cm−1 for 1981, and the mean was 6.20 μS cm−1. In 1982 it ranged from 3.21 to 8.53 μS cm−1; the mean was 5.12 μS cm−1. For 1983, it ranged from 3.40 to 6.19 μS cm−1; the mean was 4.95 μS cm1. The mean electrolytic conductivity of snow from Greenland was much lower than that of snow in Hanover, New Hampshire.

Concentrations of particulate matter in snow from Greenland ranged from 0.24 to 2.40 mg kg−1; the mean was 1.37 mg kg−1. The particulate matter was examined by scanning electron-microscopy. Several kinds of silicate minerals, spherules and unidentified organic particles were found. Spherules found in the snow samples are glass, Fe-, Ti- and Ca-rich, and considered to be fly-ash particles from coal combustion.

A box model combining the different physical components of the coupled ocean, atmosphere, sea-ice and land-ice climate system is used to study the possible role of sea ice in the glacial-interglacial oscillations. In this paper we investigate the teleconnection between the two hemispheres, and suggest a mechanism which can explain the observed Southern Ocean sea-ice variability during glacial-interglacial cycles. The teleconnection mechanism involves changes in the temperature of the water transported from the Northern to the Southern Hemisphere by the thermohaline circulation (THC), rather than the amplitude of the THC as has often been suggested. The sequence of events proposed by this model indicates that it would be especially interesting to obtain accurate information on the relative timing of sea-ice and land-ice variations. Fuller general circulation models and new sea-ice proxy data are needed to quantify the relative role of the proposed teleconnection mechanism.

The total area of glacierization of the Tien Shan in the boundary area of the USSR is about 8000 km2. The computation of mass balance was determined for this area in 12 river basins.

In computation procedure, the vertical profile of snow accumulation in these regions and exponential dependence of variation of ablation with altitude are used. Thus the mass balance in each basin, bn, was calculated on the basis of these curves and represented in its relation with the equilibrium line altitude (ELA). It is shown that the relation ELA = f(bn) is linear when the range of bn values is close to zero, and in all altitude intervals this relation can be described by hypsographic curves, in all basins bn positive up to an ELA elevation of 3450 to 3500 m a.s.l. For average annual altitude of ELA, bn is negative for all regions. So the glaciers of these mountains add about 4 km3 of water to the total annual runoff.

A key measure of our understanding of polar glaciation is the ability to model the initiation, maintenance, and elimination of glaciation over Antarctica and high-latitude land masses in the Northern Hemisphere. Studies that address questions of Cenozoic Antarctic glaciation, as well as studies that address questions of Pleistocene glaciation in the Northern Hemisphere, are described in some detail. The intention is to emphasize and discuss issues that are important in modeling these types of glacial events as much as to present specific results.

A high-precision, self-operating storage precipitation gauge was designed and field-tested. It consists of a cylinder-shaped container that incorporates antifreeze solution to melt snow and a quartz-crystal pressure sensor to detect mass of the contained liquid. Field trials showed performance to be at least equivalent to the Japanese standard gauge. A novel feature of the developed instrument is that it also measures a parameter related to wind speed, which is the basis for a catch correction. The instrument is simple, robust and can be battery-operated, therefore making it useful for winter precipitation measurements at sites where electric power supply is unavailable.

To compare results of icing studies conducted in wind tunnels with natural icing conditions, a series of rotor icing studies were made on top of Mt. Washington, New Hampshire. The results indicated that considerable differences exist between the two under conditions of similar liquid water content and temperature. The wet-to-dry growth transition temperature, for instance, with comparable temperature and liquid water content, may be more than 10°C higher under natural conditions than in wind tunnel studies. The possible cause of such discrepancies was found to be the vapor saturation existing in most laboratory experiments. The transition temperature of ice accretion measured in natural fog on board an aircraft agreed better with the results of the Mt. Washington study.

This paper provides the first evidence for sea-ice formation in the Cordillera Darwin (CD) fjords in southern Chile, which is farther north than sea ice has previously been reported for the Southern Hemisphere. Initially observed from a passenger plane in September 2015, the presence of sea ice was then confirmed by aerial reconnaissance and subsequently identified in satellite imagery. A time series of Sentinel-1 and Landsat-8 images during austral winter 2015 was used to examine the chronology of sea-ice formation in the Cuevas fjord. A longer time series of imagery across the CD was analyzed from 2000 to 2017 and revealed that sea ice had formed in each of the 13 fjords during at least one winter and was present in some fjords during a majority of the years. Sea ice is more common in the northern end of the CD, compared to the south where sea ice is not typically present. Is suggested that surface freshening from melting glaciers and high precipitation reduces surface salinity and promotes sea-ice formation within the semi-enclosed fjord system during prolonged periods of cold air temperatures. This is a unique set of initial observations that identify questions for future research in this remote area.

Deep-water ‘stable’ subglacial lakes likely contain microbial life adapted in isolation to extreme environmental conditions. How water is supplied into a subglacial lake, and how water outflows, is important for understanding these conditions. Isochronal radio-echo layers have been used to infer where melting occurs above Lake Vostok and Lake Concordia in East Antarctica but have not been used more widely. We examine englacial layers above and around Lake Ellsworth, West Antarctica, to establish where the ice sheet is ‘drawn down’ towards the bed and, thus, experiences melting. Layer drawdown is focused over and around the northwest parts of the lake as ice, flowing obliquely to the lake axis becomes afloat. Drawdown can be explained by a combination of basal melting and the Weertman effect, at the transition from grounded to floating ice. We evaluate the importance of these processes on englacial layering over Lake Ellsworth and discuss implications for water circulation and sediment deposition. We report evidence of a second subglacial lake near the head of the hydrological catchment and present a new high-resolution bed DEM and hydropotential model of the lake outlet zone. These observations provide insight into the connectivity between Lake Ellsworth and the wider subglacial hydrological system.

The first European Remote Sensing Satellite (ERS-1) synthetic aperture radar (SAR) images offer opportunities for studying glacier surface properties and near-surface features. Analysis of back-scatter values from digital SAR data from 18 January, 7 June, 1 September and 25 October 1993 of Brúarjökull, an outlet glacier on the northeastern margin of the Vatnajökull ice cap, Iceland, that has a history of episodic surges, reveals several back-scatter boundaries that may relate to glacier facies and, inferentially, to mass balance. For example, a strong back-scatter boundary on the 18 January image of the snow-covered glacier, representing a back-scatter coefficient, σ°, difference of 4.34dB, appears to coincide with the position of the transient snow line at the end of the 1990–91 budget year. The boundary is visible on the 7 September 1991 Landsat thematic mapper (TM) image. The terminus is very difficult to define because of back-wasting from the last surge (1963–64) but is most easily delineated on the 1 September 1993 SAR and the 7 September 1991 TM images, in part due to the presence of ice-margin lakes.

The synthetic aperture radar (SAR) data have been used to study sea ice with respect to its motion and formation/deformation. With the prospect of the Alaska SAR Facility development in the near future, there is a great need for robust and efficient sea-ice analysis techniques. This paper presents a sea-ice motion analysis technique that can be used for (1) local motion analysis of a selected ice patch and (2) a global ice motion over the entire image area. Though there are several sea-ice motion tracking techniques, they do not provide the required operational speed or robustness. In order to meet the operational speed requirement (over fifty images per day), we have developed a sea-ice motion analysis technique which requires very little human interaction and much simplified computation. The proposed technique uses a subset of easily distinguishable features to predict global motion characteristics and apply template matching over a predicted search area. We applied the developed technique to two pairs of SEASAT SAR images, one pair with a minor motion of “ice pack” and another with a larger and discontinuous motion of “fast ice”. The two major achievements of the new approach are: first, development of a set of computer-aided tools for feature selection and registration and, secondly, implementation of an optimal search strategy for automatic template matching via a motion prediction model.