Atmospheric aerosol particles have been sampled since 1985 at the Brazilian Antarctic station, Comandante Ferraz (62°05' S, 58°23 5'W) Stacked niter units were used to collect particles with an aerodynamic diameter of less than 10μm. The elemental concentration was measured by particle-induced X-ray emission, yielding data for 23 elements: Na, Mg, Al, Si, P, S, Cl, K, Ca, K, V, Cr, Mn, Fe, Ni, Cu, Zn Sc, Br Kb, SrZr and Pb. The detection limit was typically near 5 ng m −3 for elements with atomic number (z) less than 20, and Oingm for 21 < z <.30. Principal-factor and cluster analyses identified four sources for the Antarctic aerosol: fine and coarse sea salt, soil dust and sulphates. The fine-mode non-sea-salt sulphate concentration showed a clear seasonal pattern accompanying the biological cycle of algae, with minimum during winter. Some elements, such as Ni and Pb, showed very high enriched concentrations relative to the bulk sea-water composition. This indicates the existence of sources of regional or long-range transported pollution.

To complement a technique to detect internal structures of seasonal snow covers and glacier firn with ground-penetrating radar (GPR), we carried out calibration experiments and an observation of winter snow cover (5.7m thick dry snow with numerous ice layers) with an 800 MHz GPR. In particular, we aimed to discriminate periodic noise, which is inherent in GPR, from radar echoes and to obtain a relationship between the observed reflection strength and the magnitude of density contrasts. Experiments were done in air to evaluate noise levels and receiver characteristics of this system. Based on these, we removed noise from radar echoes in the snow-cover observation. We recognized numerous marked echoes in a noise-free radargram. The depths of these echoes coincided roughly with those of large density contrasts observed in the snow pit. Thus, we argue that the echoes correspond to thin ice layers. Furthermore, the minimum density contrasts detected by this GPR are found to vary from about 100 to 250 kgm–3 at 1–6m depth in the seasonal snow cover.

The determination of snow-grain characteristics (such as type or size) is crucial for validating snow models and interpreting remote-sensing data. Until now, the size and type of snow grains have been estimated in the field. Nowadays, the transport of a snow sample in iso-octane allows laboratory analyses. The objective analysis of snow-grain digital images has been developed at the Centre d'Études de la Neige since the mid 1980s. The images are taken in a cold room and stored on a video disk. The calculation of the relevant parameters for snow characterization has been developed. Recently, the hardware- and software-systems have been upgraded, allowing quicker and easier analyses. Finally, a procedure designed to determine snow types from image analysis has been developed and calibrated using 65 snow samples. For that purpose, independent experts have determined the snow type (as defined by the International Classification) of each sample. The procedure has been verified using an independent set of snow images. This semi-automated determination gives 97% correct results on granular-snow types. However, it is not reliable for precipitation particles.

During an inland traverse expedition along the route from Zhongshan station on the coast to Dome A (about 4200ma.s.l.; 1400 km from Zhongshan) in East Antarctica in 1998/99, three snow pits with a depth of 2.1–3.3m were sampled continuously. Snow pits were located at sites 800–1100km from the coast, with altitudes varying from 2850 to 3760 m. The samples were analyzed for stable oxygen isotope and major ions. Seasonal variations in δ18O are not clear, so initial dating was made through comparison of concentration profiles of major ions and then adjusted according to the visible stratigraphy. Generally, average ionic concentrations decrease with increasing altitude and hence distance from the coast, but NH4+ and Ca2+ have relatively high values at a site 1000 km inland. Ionic concentrations tend to increase with depth at lower altitudes, but the opposite is true at higher altitudes. Accumulation rates increase with depth at site DT401 (3760ma.s.l.; 1097 km from Zhongshan) and decrease at DT364 (3380ma.s.l.; 1022 km from Zhongshan) and DT263 (2850ma.s.l.; 820 km from Zhongshan), suggesting that differences in regional trends exist. In all snow pits, Na+ and Cl– concentration profiles have a very good positive correlation. Profiles of nssSO42– in the pits show quite different features. At 3760ma.s.l, no remarkable nssSO42– peaks can be distinguished, but one and three peak sets are quite striking at 3380 and 2850 m, respectively.

Finsterwalderbreen is a 35 km2, polythermal glacier in southern Spitsbergen, which last surged at around the start of the 20th century, and is still in the quiescent phase. Surface elevations measured several times since 1898 show strong thinning and retreat at the front, and gradual build-up in the accumulation area. Present-day annual velocities increase from about 1 m a–1 at the snout to a maximum of 13 m a–1 near the equilibrium line, then drop to 5 m a–1 at the bergschrund. Summer velocities are higher than the annual average, and winter velocities are lower (10–60% of summer velocities, where both are measured over several months). Velocities measured along the glacier centre line in 1950–52 are higher than those measured in 1994–95 in the upper basin, but are lower in the ablation area, which may be attributable to changes in surface profile on recovery from the surge. The measured modern ice flux (≈2.5 x 10–3 km3 a–1 w.e.) is only about 60% of the flux required to maintain balance (≈4.1 x 10–3 km3 a–1 w.e.), as determined from continuing mass-balance studies. Multi-frequency radar profiles show that most of the glacier is at the pressure-melting point at the base. This is consistent with hydrological studies showing high suspended-sediment loads, and hydro-chemical evidence of high sulphate levels, both indicating a well-developed basal drainage system during the summer which probably accounts for the seasonal velocity variations. Since the glacier still has a temperate bed, and appears to be building up in the accumulation area, it may be developing towards another surge.

Crevasse initiation is linked to strain rates that range over three orders of magnitude (0.001 and 0.163 a-1) as a result of the temperature-dependent nonlinear rheological properties of ice and from water and debris inclusions. Here we discuss a small cold glacier that contains buried crevasses at and near an ice divide. Surface-conformable stratigraphy, the glacier’s small size, and cold temperatures argue for limited rheological variability at this site. Surface ice-flow velocities of (1.2-15.5) ± 0.472 m a- 1 imply classic saddle flow surrounding the ice divide. Numerical models that incorporate field-observed boundary conditions suggest extensional strain rates of 0.003-0.015 a- 1 , which fall within the published estimates required for crevasse initiation. The occurrence of one crevasse beginning at 50 m depth that appears to penetrate close to the bed suggests that it formed at depth. Field data and numerical models indicate that a higher interior stress at this crevasse location may be associated with steep convex bed topography; however, the dynamics that caused its formation are not entirely clear.

Regional summer temperatures (TS), derived from tree rings, and large-scale atmospheric circulation indices (North Atlantic Oscillation (NAO)) were used to infer the mass balance of Storglaciären, Sweden, on annual and decadal timescales back to AD 1500. Winter (January–March) NAO was not a suitable proxy for interannual winter balance variability, but seemed to have substantial influence on decadal timescales. TS were highly correlated to the summer balance, but also to the annual net balance. This association was much weaker on decadal timescales, mainly because of the increased maritime climate around 1980. Storglaciären net balance was modelled back to AD 1500 with annual resolution (using TS as a predictor), and AD 1664 with decadal resolution (using TS and NAO as predictors). Both reconstructions displayed similar evolution. Negative mass balances dominated most of the 16th century, followed by a longer period of predominantly positive mass-balance years culminating in about 1750. This is in agreement with previous suggestions of Holocene maximum expansion of Storglaciären at that time. Subsequently, the mass balance is highly variable, with an increased number of negative years. The build-up to the well-documented early-20th-century advance is evident as mass balance becomes progressively more positive towards the early 20th century.

The 320 kyr climatic record from the 2503 m Dome Fuji (Antarctica) ice core was analyzed using two electrical methods: AC-ECM and ECM (electrical conductivity measurements). AC-ECM is a method to detect the complex admittance between electrodes dragged on the ice surface with mm-scale resolution and uses 1V and 1 MHz. the ratio of the real to imaginary part of the admittance is the AC loss factor, which responds linearly to the amount of sulfuric acid and hydrogen ions. Both the AC loss factor and the ECM current respond to acid, but the ECM signal tends to saturate at high acidities. Dome Fuji ice was measured to be highly acidic, with background values of 2–7 μM, and had 4500 major peaks with acidities of up to 90 μM. This ice-core evidence and earlier snow-chemistry survey around the dome region indicates that Dome F may have a better connection to the stratosphere than have sites at lower altitude, which allows more stratospheric aerosol and gases to reach the snow surface. Acidity tends to be high in interglacial periods, but correlation between acidity and δ18O is not straightforward. Electrical signals decreased and smoothed out with increasing depth; the diffusion coefficients deduced from this smoothing were 10–102 times greater than in solid ice. the ice core exhibited electromechanical effects and expelling effects from sulfate peaks.

Laboratory experiments were done to better understand the electrical conduction mechanisms of impure, polycrystalline ice as represented by the 2503 m Dome Fuji (Antarctica) ice core. Also, two electrical measurement techniques for ice cores were compared and their usefulness for determining the acidity of ice cores was studied. We measured the electrical conductivity and complex permittivity of 167 slab-ice samples at frequencies from 20 Hz to 1 MHz. Measurements were performed at –21˚C for all samples, and at –110˚ to –20˚C for several samples, to examine the effects of temperature. We found linear relations between the AC loss factor and the molarity of sulfuric acid, and between the high-frequency-limit conductivity and the AC loss factor. Thus, the acidity levels can be determined from the AC loss factor. In contrast, the electrical conductivity measurement (ECM) current correlated weakly with the other parameters; furthermore, the correlation worsens at larger signal. In several samples containing high acidity, the dielectric properties had distinct changes near –81˚C. We argue that these changes were caused by a change from a liquid-vein-mediated conduction mechanism above the eutectic point of the solute/water/ ice system to a solid-phase conduction mechanism at lower temperatures.

In order to measure total ice thickness and surface snow accumulation in Antarctica, we have designed and built a surveying system comprising two types of radar. This system is aimed at having low power consumption, low weight/volume and low construction cost. The system has a pulse-compression radar to measure ice thickness, and a frequency-modulated continuous wave (FM-CW) radar designed to measure hundreds of meters of surface snow/firn layers with high resolution. The pulse-compression radar operates at 155MHz, 20 MHz of bandwidth; and the FM-CW radar operates from 550 to 900 MHz. The system was tested in December 2010 at Union Glacier (79°46'S, 83°24'W), West Antarctica, during an oversnow campaign, where Union and other nearby glaciers (Schanz, Schneider and Balish) were covered through 82 km of track. Ice thickness of 1540m and snow/firn thickness of 120 m were detected in the area. The collected data allowed the subglacial topography, internal ice structure, isochronous and the snow/ice boundary layer to be detected. Here we describe radar electronics, their main features and some of the results obtained during the first test campaign. Further improvements will focus on the adaptation of the system to be implemented on board airplane platforms.

Numerous examples of synthetic aperture radar (SAR) imagery of ice sheets are shown and prominent features of glaciological importance which appear in the images are discussed. Features which can be identified include surface undulations, ice-flow lines, crevasses, icebergs, lakes, and streams (even lakes and streams which are inactive or covered by snow), and possibly, the extent of the ablation and wet snow zones. SAR images presented here include both L-band data from the Seasat satellite and X-band data from an airborne radar. These two data sets overlap at a part of eastern Greenland where a direct comparison can be made between two images. Comparison is also made between SAR and Landsat images in western Greenland. It is concluded that SAR and Landsat are highly complementary instruments; Landsat images contain minimal distortion while SAR’s all-weather, day/night capability plus its ability to penetrate snow provide glaciologists with an additional and very powerful tool for research.

Two geodetic airborne laser altimeter (ALA) systems coupled to Global Positioning System receivers acquired submeter-resolution topographic profiles of the lower parts of Breidamerkurjökull and Skeidarárjökull, Iceland, in May 1989 and September 1991 (Skeidarárjökull) and of Jakobshavns Isbræ, Greenland, in April 1992. Maximum measured crevasse depths on Breidamerkurjökull, Skeidarárjökull and Jakobshavns Isbræ were 20.7, 36.1 and 50.2 m, respectively. Crevasse spacings were 43 m (45 crevasses km−1) for Breidamerkur jökull, 46–51 m (25 crevasses km−1) for Skeidarárjökull and 20–40 m (lower part) or 50–80 m (upper part) of Jakobshavns Isbræ (27 crevasses km−1). Surface slopes were ~2.4° for the lower 11 km of Breidamerkurjökull, ~0.8° for the lower 10 km of Skeidarárjökull and 1.55° for the lower 28 km of Jakobshavns Isbræ (with a range of 0.55° for the final 17 km to ~6.3° for a steep central part several km in length). Average longitudinal strain-rate values, estimated by assuming a bulk ice temperature of 0°C and a density of 880 kg m−3, ranged from 0.12 a−1 for Breidamerkurjökull, to 0.63 a−1 for Skeidarárjökull; values for Jakobshavns Isbræ fell between 1.3 and 1.7 a−1. Remote sensing of glacier microtopography by ALA offers a potential new tool for determining crevasse morphology, spatial density and spacing, meter-scale local slopes, long-wavelength gradients and derived strain rates.

An ice-surface temperature retrieval algorithm for the Greenland ice sheet was developed using NOAA 11 thermal radiances from channels 4 and 5. Temperature, pressure and humidity profiles, cloud observations and skin temperatures from the Swiss Federal Institute of Technology (ETH) camp, located at the equilibrium line altitude at 49°17′W, 69°34′N, were used in the LOWTRAN 7 model. Through a statistical analysis of daily clear sky profiles, the coefficients that correct for the atmospheric effects were determined for the ETH-Camp field season (May to August). Surface temperatures retrieved by this method were then compared against the in situ observations with a maximum difference of 0.6 K. The NOAA 11 narrow-band planetary albedo values for channels 1 and 2 were calculated using pre-launch calibration coefficients. Scattering and absorption by the atmosphere were modelled with LOWTRAN 7. Then, narrow-band albedo values for the AVHRR visible and near infrared channels were compared with in situ high resolution spectral reflectance measurements. In the visible band (580–680 nm), AVHRR-derived narrow-band albedo and the in situ measurements corrected with radiative transfer model LOWTRAN 7 showed a difference of less than 2%. For the near infrared channel (725–1100 nm) the difference between the measured and modelled narrow-band albedo was 14%. These discrepancies could be either the result of inaccurate aerosol scattering modelling (lack of the in situ observation), or the result of sensor drift due to degradation.

In the Antarctic, climate-scale anomalies of surface temperature (Ts) are associated with the atmospheric circulation and also sea-ice conditions. Negative (positive) anomalies of station Ts tend to accompany more (less) extensive sea ice in broadly similar longitudes. However, the relationship between temperature and sea-ice conditions during large interannual variations of the circulation has been little explored, as has its association over longer distances within Antarctica. This study examines the inter-associations between Ts at seven automatic weather stations in East Antarctica and the Ross Sea area, and sea-ice conditions in the sector 30° Ε eastward to 60° W for the three ice-growth seasons (March-October) of 1987-89. Strong between-year differences occur in the intercorrelalions among station Ts, sectoral içe extent and the relationship between the two climate variables, especially for 1988 and 1989. These differences are also expressed in the patterns of cold-air mesoscale cyclogenesis over sub-Antarctic latitudes. The study indicates that the Ts-sea-ice link is modulated strongly in the presence of large-scale interannual anomalies of the atmospheric circulation, including the El Niño-Southern Oscillation (ENSO).

Evacuation of the ground-water intruding into a coal mine beneath Høganesbreen, Svalbard, is difficult and expensive. To solve this problem, it was proposed that the mine be connected to the ice–bedrock interface. Pumping hot water from the mine should establish a flow path along the glacier bed where the ground-water would drain gravitationally. In this paper, we assess the requirements for maintaining such a drainage system in open-channel conditions. To obtain the bedrock topography, we determined the ice thickness by ground-penetrating radar and subtracted it from the surface elevation measured by global positioning system. A measured temperature profile at the site where the mine should connect to the glacier bed (140m depth) revealed that the basal ice is below the pressure-melting point. The locations of major subglacial conduits were estimated using a hydraulic-potential approach. We adopted a model oftime-dependent discharge through a Röthlisberger channel to calculate a set of scenarios using different flow-law parameters. Results of the simulations suggest that for the given conditions, water flow would be pressurized, thereby inhibiting the gravitational drainage of the mine.

Sequential visible and radar satellite imagery is used to document the fluctuations of 39 outlet glaciers on James Ross Island (JRI; 64° S, 58° W), Antarctic Peninsula. The monitoring time interval of 17.4 years extends from late 1975 until early 1993. The study is based on synergistic use of different sensors for monitoring glacier variations. The digitally enhanced Landsat TM images also allowed definition of boundaries between grounded and floating ice within Röhss Bay and detection of ice rumples, resulting in an improved measurement of the areal extent of JRI. In addition to glacier boundaries, the analyzed ERS-1 SAR images provide information on morphological properties of snow and ice. The satellite data show a general glacier retreat since 1975, resulting in clear decrease of overall glacier area on JRI. Of 39 glaciers measured, 33 glaciers retreated in the period 1975–93, 15 of which showed significant retreat in comparison to glacier size. This is in accordance with the pronounced atmospheric-warming trend recorded during the last two decades on the Antarctic Peninsula. The analysis of glacier areas on JRI thus provides a base line for detection of future changes.

Digital maps and terrain models are used to calculate maximum snow-avalanche run-out distance based on topographic parameters. Maps of 1:50 000 scale are found to be accurate enough for the purpose. 113 well-known avalanches are discussed in this paper. A computer system is used to calculate terrain parameters such as rupture area (A), avalanche-path length (L), avalanche-track lengths (L1L2), and run-out lengths (L3). Maximum run-out angle (α), avalanche-track angle (β). and average angle of rupture zone (γ) are also found by computer. The use of computer and terrain model reduces subjective judgement of parameters to a minimum. Run-out distance was found to be best expressed by the regression equation:

α = 0.91β + 0.08γ–3.5°. R2 = 0.94, S = 1.4°.

L = 0.93L1 + 0.97L2 + 0.61A + 182 m. R2 = 0.96, S = 137 m.

A study of pollen grain concentration in surface snow and ice cores at 15 sites in the Canadian high Arctic and one site near the tree line, together with published pollen deposition rates south of the tree line has shown long-range dispersal of pollen from the boreal forest to the limits of our area on the Arctic Ocean close to Svalbard and the North Pole. There are no discernible trends of deposition rates within the high Arctic which suggests extremely long trajectories with strong zonal components; some of the pollen may have an Eurasian source. We relate the trajectories to synoptic patterns in the mid- and high Arctic.

Temperature-depth measurements from two sites on Crary Ice Rise, Antarctica are analyzed to deduce the time the ice first grounded at each location. At the thicker site (480 m), the best estimate of the time since grounding is 1100 years. At the shallower site (369 m) the grounding is more recent, 580 years ago, and there is evidence that basal cooling was delayed for 450 years while water at the base was freezing. This analysis leads to the conclusion that Crary Ice Rise was formed by at least two separate grounding events and is not a remnant of a more extensive grounded ice sheet which occupied the present position of the Ross Ice Shelf.

Ice flow from the ice sheets to the ocean contains the maximum potential contributing to future eustatic sea-level rise. In Antarctica most mass fluxes occur via the extended ice-shelf regions covering more than half the Antarctic coastline. The most extended ice shelves are the Filchner–Ronne and Ross Ice Shelves, which contribute ~30% to the total mass loss caused by basal melting. Basal melt rates here show small to moderate average amplitudes of <0.5ma–1. By comparison, the smaller but most vulnerable ice shelves in the Amundsen and Bellinghausen Seas show much higher melt rates (up to 30 ma–1), but overall basal mass loss is comparably small due to the small size of the ice shelves. The pivotal question for both characteristic ice-shelf regions, however, is the impact of ocean melting, and, coevally, change in ice-shelf thickness, on the flow dynamics of the hinterland ice masses. In theory, ice-shelf back-pressure acts to stabilize the ice sheet, and thus the ice volume stored above sea level. We use the three-dimensional (3-D) thermomechanical ice-flow model RIMBAY to investigate the ice flow in a regularly shaped model domain, including ice-sheet, ice-shelf and open-ocean regions. By using melting scenarios for perturbation studies, we find a hysteresis-like behaviour. The experiments show that the system regains its initial state when perturbations are switched off. Average basal melt rates of up to 2 ma–1 as well as spatially variable melting calculated by our 3-D ocean model ROMBAX act as basal boundary conditions in time-dependent model studies. Changes in ice volume and grounding-line position are monitored after 1000 years of modelling and reveal mass losses of up to 40 Gt a–1.