Recently, a 700 m long ice core was drilled at Mizuho Station (2230 m a.s.1.), 270 km south-east of Syowa Station and situated in a typical katabatic-slope region.

In order to obtain basic knowledge for dating the core and for interpreting climatic change and depositional environment change along the core, a study of the regional characteristics of the snow-deposition regime on Mizuho plateau has started. Surface-firn cores 10–30 m deep and snow-stake data obtained along the traverse routes on Mizuho plateau since 1970 were analyzed.

The general trend of annual snow accumulation and the regional characteristics of the δ18O profile of snow cover were obtained.

Extensive echo-sounding was carried out in east Dronning Maud Land during the 1984 field season. A 179 MHz radar with separate transmitting and receiving antennae was used and the echoes were recorded by a digital system to detect minute reflections. The results gave cross-sections of the ice sheet along traverse routes from lat. 69 °S. to 75°S, Detailed observations on the ground at Mizuho station showed that there was elliptical polarization in the internally reflected echoes when two antennae, kept in parallel with each other, were rotated horizontally. The internal echoes were most clearly distinguished when the antenna azimuth was oriented perpendicular to the flow line of the ice sheet. The internal echoes with a high reflection coefficient were detected at depths of 500–700 m and 1000–1500 m at Mizuho station. Since a distinct internal echo at a depth of 500 m coincides with a 5 cm thick volcanic ash-laden ice layer found in the 700 m ice core taken near the observation site, these echoes may correspond to the acidic ice layers formed by past volcanic events in east Dronning Maud Land.

The dielectric constants of alpine snow samples with different stages of metamorphism and with different liquid water saturations have been measured in the frequency range of 10Hz to 50MHz using a plate condenser and network-analyzer. The limiting static dielectric constant, €s’, has been derived from the measured frequency dependence of the complex permittivity of snow by a least-square-fit using the model of Cole-Cole. A strong dependence of e on porosity, liquid water content and on the shape of the snow grains was found. Calculations of shape factors from the measured static permittivity based on the model of Polder and van Santen are given, and are compared to shape factors derived from an analysis of photographs of the snow samples.

A map of the surface elevation for the southern half of the Greenland ice sheet has been produced from data gathered by the radar altimeter on board the SEASAT satellite. From June 1978 until September 1978, useful data were collected during most passes over the ice sheet, but data was not collected continuously along each pass. Over 85 000 separate ranges were obtained from the satellite to the surface at points spaced 662 m apart along each orbital pass.

Techniques required for the reduction of the recorded return waveforms to surface elevations have previously been described in a series of papers (Martin and others, 1983; Brenner and others, 1983; and Zwally and others, 1983). Once all corrections have been applied to the range data due to atmospheric effects, ocean and earth tides, and orbital perturbations, the set of ranges at orbital crossing points (where ascending orbits crossed descending orbits) had a mean relative error of 2.9 m, with a standard deviation of ±2.9 m. Elevations over the flatter and smoother portions of the ice sheet have a precision as small as ±0.25 m, while data over sloping and rough areas are of lower quality. Along each orbital track, the data are corrected for the slope-induced error.

The reduced set of surface elevations has been interpolated to assigned elevation values at the nodal points of a regular grid with a 10 km spacing (polar stereographic projection). This grid was then contoured at intervals of 50 m above 2400 m altitude and 100 m at lower elevations. Similar grids of slope-induced error corrections were contoured to provide some measure of its effect on the data. Ancillary plots of parameters of the fitting and gridding process are included to help in estimating the quality of the derived surface topography in different regions.

The surface elevation contour map shows the existence of distinct drainage basins within the ice sheet — most notably in the southern and eastern areas. This detail will prove most useful in the delineation of these basins for hydrological or glaciological studies. In combination with ice-thickness data, these elevation data permit a more accurate measurement of the bedrock elevation. The corrected altimeter data in orbital-pass and map format have been provided to the National Space Science Data Center at Goddard Space Flight Center and to the World Data Center-A, Glaciology, as a source of information to be used by other scientific investigators. These data have already been used to produce detailed maps of the topography in more localized areas (e.g. Figure 2, from Zwally and others, 1983 and Figure 2 of Bindschadler, 1984).

The glaciers of the Antarctic Peninsula are believed to react rapidly to climatic fluctuations. Thus it is of great interest to find methods for monitoring regional climate variability in this region, Two small glaciers on the Antarctic Peninsula were chosen to monitor the accumulation and ablation pattern of the snow cover in respect to climate variations. During two summer seasons, synthetic aperture radar pulse-repetition interval images from the European ERS-1 active microwave satellite instrument were collected. Simultaneously, micro-meteorological measurements with simple automatic weather stations were carried out at three locations on the glaciers. Energy available for snowmelt was computed using the bulk transfer equations. Incorporating a digital terrain model and a model for shortwave irradiance, estimates of the energy available for melt were then calculated for the entire glaciers. The resulting time series of spatially distributed information on available energy can be used to separate periods and areas with snow-melt from periods and areas with completely frozen snow cover. The same separation can be achieved from the ERS-1 imagery. Integrating both the remote-sensing technique and the ground observations, it may be possible to establish a combined method to monitor the effects of weather patterns on a seasonal basis.

In order to obtain new information concerning the anomalous properties of Antarctic ice previously observed through electrical measurements, we have studied specimens from a coastal site by means of internal friction measurements in the 1 Hz range. The results have been compared to previous ones obtained with polar ice from Dome C and electrical measurements have been made on the same samples in order to confirm the anomalous behaviour of such material.

Two possible explanations of the anomalous properties of polar ice are discussed, namely the role of impurities and the ageing effect. It seems improbable that impurities could be responsible for such properties due to their low concentration. Some experiments, however, lead us to interpret the behaviour of polar ice in terms of modifications with time of the concentration and distribution of intrinsic point defects present at the beginning of the existence of the ice microcrystals

Numerical experiments, where a simple ice-sheet model was coupled with sediment-deformation models, were performed to investigate the transport of glacigenic material to the western Barents Shelf during the Late Weichselian. The ice-sheet model, and its environmental inputs, has been matched previously with a series of geological datasets relating to the maximum extent of the ice sheet (Howell and others, http://www.ggg.qub.ac.uk [rp05/1999]). Additional geological data on the volumes of sediment delivered to the Bear Island fan (Barents continental margin) are available for comparison. The experiments indicate the sensitivity of sediment transport and deposition to variations in (a) the ice-stream model and (b) a variety of model parameters. Two ice-stream models were used: (1) a height-above-buoyancy model, in which basal velocity is controlled by basal driving stress and a buoyancy-induced reduction in the normal load beneath a marine-based ice sheet; and (2) a modified version of the method presented by Alley (1990) in which basal velocity is related to pore-water pressure, sediment thickness, and driving basal stress. The results of the two different models were then compared. An extensive set of sensitivity tests was carried out to determine sediment-transport response to changes in the model’s parameters. Results indicate that, using physically realistic parameters for deforming subglacial sediment, both models reproduce the volume of Late Weichselian sediment measured on the Bear Island fan. Results from both models are sensitive to (1) cohesion of the sediment and (2) the thickness of deforming sediment beneath the ice sheet. The two models exhibited different degrees of sensitivity to the sediment parameters, with the height-above-buoyancy model proving to be less sensitive to variations in the thickness of the deforming sediment layer than the model proposed by Alley (1990). The differences between the two models examined here highlight the need for a comprehensive comparison of all the methodologies for calculating basal-ice motion currently in use.

This paper focuses on the surface mass balance of a horizontally homogeneous snowfield, with emphasis on the effects of snowdrift sublimation. A one-dimensional model of the atmospheric boundary layer that includes snowdrift physics and thermodynamics is used. In sufficiently strong winds, snow particles are eroded from the surface. Once airborne, they are susceptible to sublimation. Averaged over longer time periods, the net erosive flux equals sublimation of snowdrift. However, model results show that there is no such balance in the course of a snowstorm event. They also indicate that snowdrift sublimation tends to enhance net erosion, but the increase occurs more slowly than the mass transfer by snowdrift sublimation, and the maximum is smaller. This difference in temporal behaviour influences the average erosion rate owing to non-linear interactions between snowdrift sublimation, drift density and erosion. Since the increase in relative humidity due to snowdrift diminishes surface sublimation, the average change in total ablation induced by snowdrift sublimation remains small. Observations made during snowdrift episodes in Antarctica agree qualitatively with some of the model results.

The relationship between the behavior of water in snow and its microstructure is crucial to improve the prediction of wet snow disasters. X-ray computed tomography (X-ray CT) is frequently used to observe snow microscopically. However, distinguishing between ice and water in the X-ray images is difficult because ice exhibits an X-ray absorption coefficient similar to that of water. In contrast, magnetic resonance imaging (MRI) acquires nuclear magnetic resonance (NMR) signals of protons in a liquid and visualizes the NMR signal intensity, enabling discrimination between water and ice signals. However, snow grains and pore spaces cannot be distinguished in MRI images because they do not generate NMR signals.

To investigate the relationship between the microstructure of snow and the distribution of liquids in snow, we developed a novel method that combines X-ray CT and MRI images to compensate for the disadvantages associated with each method. Using this method, we successfully visualized where liquid (C12H24) occupied pore spaces. We also showed the possibility of using C12H24 instead of water to obtain water retention curve of snow cover, which is a fundamental aspect of hydraulic properties. Although there is room for improvement in the visualization of water in snow, such as shortening the imaging time to escape snow metamorphosis and image superimposition methods, this method is expected to effectively elucidate the behavior of water in snow and clarify the characteristics of wet snow.

We revise and evaluate frontal ablation fluxes obtained by the Open Global Glacier Model (OGGM) for Greenland's tidewater peripheral glaciers de-coupled from the ice sheet. By making use of new region-wide ice thickness and solid ice discharge data, we re-evaluate model performance and suggest future research directions to improve the ice thickness estimation of glacier models. OGGM is unable to predict individual tidewater glacier dynamics well if it has to rely only on surface mass balance estimates and the assumption of a closed budget to constrain the calving parameterization. Velocity observations are essential to constrain the model and estimate the dynamic mass loss of Greenland's tidewater peripheral glaciers.

The rate of icing in the wet growth conditions typical of ship icing and icing in freezing precipitation depends on the rate at which the heat liberated in the freezing process is transferred to the environment. A theoretical model for the heat transfer from the front half of a rough cylinder, based on boundary-layer theory, is described.

Comparisons with empirical data show that the model simulates well the overall heat transfer rate from the front half of a cylinder with distributed roughness. The theory provides improved agreement between the results of a numerical icing model and icing wind tunnel tests.

Measurements of crystal size have been made on seven firn cores drilled at sites covering a range of mean annual temperature from –12.6° to –52.5°C and a range of accumulation rate from 52 to 315 kg m−2 a−1. The sorting coefficient, which gives a measure of the dispersion of crystal sizes within a sample, shows an overall pattern when data from all cores are grouped together as a function of depth. The values are generally small near the surface, increasing to a maximum around 8 m depth, then decreasing but becoming more diffuse at greater depths. Below about 5 m depth, the crystal size increases at an essentially constant rate, which depends on temperature, but in the upper 5 or 7 m the size increases at 1.5 to 2 times this rate. The seasonal variation in temperature enhances the effective mean growth rate of crystals in the near-surface layers compared to conditions with a constant mean temperature and accounts for a part of that increase. But it is likely that vapour diffusion along strong vertical temperature gradients causes the greater part of the observed increase in growth rate. The dependence of crystal-growth rate on temperature is consistent with the Arrhenius-type relation found by other studies.

This paper describes the results of snow drift measurements made on a strong katabatic wind slope at Mizuho Station (70°42.6’S, 44°18.9’E; 2230 m above mean sea level) in East Antarctica. From the vertical profile of the mass flux of blowing snow up to 28 m above the snow surface under conditions of snow fall, the snow fall densitities have been estimated as asymptotes of the profile (Fohn 1980). Snow fall densities as asymptotes were estimated between 8x10-6 and 8xl0-5 kg/m3. Assuming a fall velocity of blowing snow particles as 0.5 m/s, above values correspond to values of the vertical flux of snow fall between 2x10-3 and 1.5xl0-1 mm/h.

Two types of experiments were performed near Upstream B Camp on Ice Stream B2 using a high-resolution ground-penetrating radar system. In the first type of experiment, tracking a metal drill tip through the upper 85 m of the ice column indicated an approximately linear decrease of wave speed with depth down to 50 m, with a constant speed of 170 ± 4 m µs−1 below. We believe the (unexpected) linearity may have been caused by one or more buried crevasses. In the second experiment, a survey of a 250 km2 grid showed a population of buried crevasses at about 30 m depth that have an estimated burial age of 210 ± 25 years, which is taken to indicate that this ice has been exhibiting streaming behavior for at least that length of time. One 3 km segment along the edge of the survey area nearest the center of the stream showed virtually flat, undisrupted stratigraphy down to the maximum depth of our measurements. The fact that this ice was accelerated from near-zero speed to its present 440 m a−1 without cracking or folding suggests that this ice may have been incorporated into the ice stream as a solid block.

During the second half of the 20th century, the Antarctic Peninsula region has undergone a long and sustained warming period, followed by a shorter but also sustained cooling period, and then a very recent return to warming conditions. All of these have profoundly impacted the glaciers peripheral to the Antarctic Peninsula. This paper focuses on the analysis of the surface mass balance monitoring of such glaciers by the glaciological method, complemented by the analysis of mass-balance estimates by geodetic methods, as well as frontal ablation estimates. We aim to summarize the current knowledge and outline the main challenges faced by investigating the mass balance of such peripheral glaciers and their current contribution to sea-level rise.

Seismic Rayleigh wave ellipticity measurements are the horizontal-to-vertical ratio of the Rayleigh wave particle motion, and are sensitive to the subsurface structure beneath a seismic station. H/V ratios measured from the ambient vibrations of the Earth are being increasingly used in glaciological applications to determine glacier and ice sheet thickness, seismic velocities and firn properties. Using the newly developed degree-of-polarisation (DOP-E) method which exploits the polarisation properties of seismic noise, we identify and extract Rayleigh waves from seismic stations in Greenland, and relate them to sea ice processes and the geology of the upper crust. Finally, we provide some suggestions for future applications of DOP-E method to gain greater insight into seasonal and long-term variability of sea ice formation and breakup as well as the monitoring of ice sheet thickness, subglacial environment and firn layers in the poles.

For the winters of 1985 to 1989, ice-edge melt rates off Labrador and eastern Newfoundland were calculated from ice charts and satellite-tracked ice beacon data. The ice charts provided ice-edge motion and ice thicknesses, while the beacons provided ice-drift rates and rates of ice-edge retreat. Over the continental slope, ice-edge melt rates, ice-drift rates and heat fluxes required to melt the ice were all higher than those over the continental shelf. Ice-edge melt rates had a mean value of 18.0 km d−1 over the slope but reduced to 4.8 km d−1 over the shelf. Similarly, the mean ice-drift rate was higher over the slope (41.5 km d−1) than over the shelf (12.7km d−1). Ice-edge melt rates increased linearly, as ice-drift rates perpendicular to the edge increased. Estimates of heat fluxes (±30%), required to melt the ice at the ice edge, reached values of 700 W m−2 for 3-day periods and had a mean of 340 W m−2 over the slope and 130 W m−2 over the shelf.