Variance analysis of the long time series of mass balances recorded on Glacier de Sarennes (45°07’ N, 6°07’ E) France, since 1949 shows that the variability can be separated linearly in two spatial and temporal terms. Annual balances deviate from their mean values over the period of record by an annual amount that is uniform over the glacier. Annual balances at each stake are therefore highly correlated, and sampling at a single site would be acceptable to record the annual deviation. A result of the linear character of the variance is the possibility of obtaining a systematic error-free estimate of the annual glacier-total budget by combining the mean annual balance obtained from photogrammetry and the annual deviation obtained from the variance analysis, rather than using the traditional area integration of balances at each stake.

Satellite radar interferometry (SRI) is used to provide new information on grounding zones in areas of the eastern Ross Ice Shelf and the Filchner Ice Shelf, Antarctica. At the times of the RADARSAT SRI passes, separated by 24 days, a tidal model predicts a change in vertical displacement of the freely floating ice of >1 m in both areas. The change in vertical position occurs over a 5–10 km flexure zone adjacent to the grounding line and would lead to a relatively high interferometric phase fringe rate. This was observed in some areas, and suitable imagery has been used to map the grounding-zone position to an estimated accuracy of 1–2 km. Results for the ice-plain area upstream of the Crary Ice Rise are consistent with the tidal model and improve the previous grounding-line estimates based on field surveys and Système Probatoire pour l’Observation de la Terre (SPOT) data. The results support the suggestion of increased ice grounding in this area, and show that a sub-ice-shelf water channel around the southern end of the Crary Ice Rise is unlikely. Results for the Filchner Ice Shelf also show that existing maps of the grounding zone can be refined. In particular, we identify a large ice rise close to the mouth of the Bailey Ice Stream.

We model runoff from glaciers in the McMurdo Dry Valleys, Antarctica, with summer (December–January) average air temperatures from 1990 to 2002 for the purpose of estimating decades- to millennial-scale glacial runoff into Lakes Fryxell, Hoare and Bonney. The relationship between summer temperatures and melt is found to be exponential near the melting temperature. We propose a variety of simple models that are calibrated using measured discharge from a number of streams draining from ten glaciers in Taylor Valley. The surface melting rate is constrained by mass-balance measurements from four of the glaciers. A model based solely on temperature produced good results (coefficient of determination, r2 = 0.71) for the south-facing glaciers, but poor results for the north-facing glaciers (r2 < 0). The inclusion of a solar radiation index increased the modeled melt from the north-facing glaciers and thus improved the results (r2 = 0.73) for the north-facing glaciers, with little change from the south-facing glaciers. Including a wind index did not improve the correlation between modeled and measured runoff.

Results from 15 years of work on glacier-bed mapping by radio-echo soundings on Finsteraar-, Lauteraar- and Unteraargletscher, Switzerland, are summarized, and a new and greatly improved map of the ice-thickness distribution presented. In contrast to the tongue of Unteraargletscher, its two main tributaries, Lauteraar and Finsteraar, are both deep and narrow, and ice-thickness determination depends on the detection of more than just the primary reflection. Migrating the data led to considerably improved bed determination. Wherever possible, additional information on ice thicknesses gained from numerous hot-water drillings to the glacier bed is used as an independent verification of the results of the radar measurements, and a fair agreement is found.

The optical system of the snow-particle counter (SPC), which was developed by Schmidt in 1977, has been improved. A laser diode is used as a light source, achieving uniform sensitivity to a blowing snow particle regardless of the location of particle trajectory within a sampling volume. The light entering a slit, which may be affected by a blowing snow particle, is perfectly detected by use of a piano-cylindrical lens and a dual-type photodiode. A signal processor has been developed to get output voltage proportional to the mass flux of blowing snow.

From the estimates based on blowing snow characteristics and wind speed profile, the new SPC system can accurately detect all the particles of effective sizes at least at a height above 0.1 m when the wind speed at a height of 1 m is less than 15 m s−1.

Considering the Fraunhofer diffraction by both the wire and the particle, the relation between a particle diameter and sensor output of the new SPC system is derived from the calibration with spinning wires.

Mass flux obtained with the new SPC system was found to be close to that with a snow trap. The system was operated continuously for at least nine days using two 35 A h lead batteries.

The results of the 1984-85 post-GISP campaigns in central Greenland are presented. Eight ice cores were obtained, some spanning up to 360 years. We present:

• I. Geographical positions and elevations at the drill sites,

• II. Density and temperature in the bore holes,

• III. Filtered δ18O profiles and accumulation-rate variations along the ice cores.

The δ18O and accumulation profiles, along with those from the 400 m Crête ice core obtained in 1974, are compared.

The accumulation-rate series over a large region have a very high coherence. This indicates that a single bore hole in this region would give a representative accumulation time series over a long period. Further, it appears that for this region there is a linear relation between the measured annual accumulation rate and the mean annual δ18O values. Thus the area between Crête and Summit, just west of the ice divide, seems to be favorable for a deep-drilling operation.

The future behaviour of the Antarctic ice sheet depends to some extent on its current state of balance and its past history. The past history is primarily influenced by global climate changes, with some small amount of local feedback, and by sea-level changes generated primarily by the Northern Hemisphere ice-sheet changes, again with a small amount of feedback from the Antarctic ice sheet. An ice-sheet model which includes ice shelves has been used to model the Antarctic region and the whole Northern Hemisphere high-latitude region through the last ice-age cycle. For the climate forcing, the results from the global energy-balance model of Budd and Rayner (1990) are used. These are based on the Earth's orbital radiation changes with ice-sheet albedo feedback. Additional sensitivity studies are carried out for the amplitudes of the derived temperature changes and for changes in precipitation over the ice-sheets. For the Antarctic snow-accumulation changes, the results from the Voslok ice core are used with proportional changes over the rest of the ice sheet. For the sea-level variations, the results generated by the Northern Hemisphere ice-sheet changes provide the primary forcing, but account is also taken of the feedback effects from bed response under changing ice and ocean loading and from the Antarctic changes.

The results of the modelling provide a wide range of features for comparison with observations, such as the margins of maximum ice extent. For the Northern Hemisphere the results indicate that the peak mean temperature shift required for the ice-edge region is about -12°C, whereas outside the ice-sheet region this change is smaller but over the ice sheets it is larger. For the Antarctic region during the ice age the interior region decreases in thickness, due to lower accumulation, while the grounding-edge region expands and thickens due to the sea-level lowering. As a result, the derived present state of balance shows a positive region over most of inland East Antarctica, whereas coastal regions tend to be nearer to balance, with some slightly negative regions around some of the large ice shelves and coastal ice streams which are still adjusting slowly to the post-ice-age changes of sea level and accumulation rates.

By consideration of model-generated atmospheric data, dominant anomalies in the synoptic circulation patterns are observed under conditions of high Antarctic precipitation. This is associated with strong moisture advection of marine origin. Examining precipitation at individual locations reveals a strong relationship between local surface temperature and precipitation amount. Days with > 5 mm of precipitation (which, on average, corresponds to about 8% of days over Antarctica) have surface temperatures that are around 10°C warmer than the mean. This bias suggest that abnormal conditions are captured in the ice-core record and that interpretation or reconstruction of palaeotemperatures will succeed only under the possibly flawed assumption that similar abnormal conditions existed at the time of deposition. Although isotopic analysis of Antarctic ice cores has been used successfully in palaeoclimate studies, a complete understanding of the underlying processes affecting the deposition of the core remains to be found. It is reasoned that by obtaining such an understanding, it may be possible to reconstruct the synoptic conditions under which accumulation occurred.

Sea-ice volume fluxes through Fram Strait, Arctic Ocean, are estimated for the two Icesat measurement periods in February/March and October/November 2003 by combining Sea-ice area fluxes, determined from Space-borne microwave observations, with estimates of the Sea-ice thickness distribution, inferred from measurements of Icesat’s Geoscience Laser Altimeter System (GLAs) instrument. The thickness is derived from Icesat data by converting its Surface elevation measurements into an ice freeboard estimate. Combined with prior information about ice density and Snow depth and density, the freeboard is converted into ice thickness. Uncertainties in freeboard estimates due to geoid model errors are reduced through the use of the recent geoid from the Arctic Gravity Project. Missing information about the ocean circulation and ocean tides is approximated locally by interpolating the Sea Surface height linearly between open leads. Meridional ice volume fluxes estimated for 79˚N using ice drift observed by AMSR-E (QuiksCAT) amount to 168 km3 (236km3) and 62 km3 (77 km3) for 30 day periods in February/March and October/November 2003, respectively. These values lie in the range of previous results from Similar Studies, but are considerably Smaller than the average ice flux during the 1990s, most likely because of a Smaller ice-drift Speed during 2003.

Radio-echo sounding surveys over the Greenland ice sheet show clear, extensive internal layering, and comparisons with age–depth scales from deep ice cores allow for dating of the layering along the ice divide. We present one of the first attempts to extend the dated layers beyond the ice core drill sites by locating the depth of the Bølling–Allerød transition in >400 flight-lines using an automated fitting method. Results show that the transition is located in the upper one-third of the ice column in the central part of North Greenland, while the transition lowers towards the margin. This pattern mirrors the present surface accumulation, and also indicates that a substantial amount of pre-Holocene ice must be present in central North Greenland.

In the summer of 2004, a firn profile, 18.3 m long, extending down to glacier ice, was recovered in the accumulation area of the largest glacier, Baishui No. 1, on Yulong mountain, the southernmost glacier-covered area in mainland Eurasia. Multivariate empirical orthogonal function (EOF) and statistical correlation analyses of major-ion data from the profile demonstrate that three distinct types of ionic material contribute to the chemical characteristics of firn in this monsoonal region: material of marine origin, which is transported by the Indian southwest monsoon; crustal materials, which come from local sources; and anthropogenic pollutants, which are produced by industrial and agricultural activities in South Asia. Although the influence of post-depositional processes on the seasonal isotopic and soluble ionic compositions is significant, dust layers in the firn profile are clearly visible. Due to the effects of meltwater percolation, the dust layers generally coincide with late-summer snow surfaces. We therefore use the dust layers, combined with the seasonal variations of electrical conductivity (EC), Ca2+ and Mg2+, to establish a depth/age scale for the firn profile. The reconstructed net accumulation has a significant negative correlation with the temperature at Lijiang, whereas the correlation between the net accumulation and the precipitation amount at Lijiang is weak. Although the δ18O time series of the firn profile was modified significantly by meltwater percolation, the correlation between annual mean δ18O values and the Indian southwest monsoon index (WSI1) is significant. This result suggests that δ18O records from monsoon-influenced temperate glaciers can provide a valuable record of past variations of the Indian southwest monsoon.

VALKYRIE (Very-deep Autonomous Laser-powered Kilowatt-class Yo-yoing Robotic Ice Explorer) is a NASA-funded project to develop key technologies for an autonomous ice penetrator, or cryobot, capable of delivering science payloads through outer planet ice caps and terrestrial glaciers. This 4 year effort will produce a cylindrical cryobot prototype 280 cm in length and 25 cm in diameter. One novel element of VALKYRIE’s design is the use of a high-energy laser as the primary power source. 1070 nm laser light is transmitted at 5 kW from a surface-based laser and injected into a custom-designed optical waveguide that is spooled out from the descending cryobot. Light exits the downstream end of the fiber, travels through diverging optics, and strikes an anodized aluminum beam dump, which channels thermal power to hot-water jets that melt the descent hole. Some beam energy is converted to electricity via photovoltaic cells, for running on-board electronics and jet pumps. Since the vehicle can be sterilized prior to deployment, and forward contamination is minimized as the melt path refreezes behind the cryobot, expansions on VALKYRIE concepts may enable cleaner access to deep subglacial lakes. This paper focuses on laser delivery and beam dump thermal design.

Regional climate modelling in conjunction with accumulation measurements collected on Antarctic traverses of the International Trans-Antarctic Scientific Expedition (ITASE) is presented as a tool for extending the spatial coverage of field measurements. The modelling of part of East Antarctica spanned the 7 year epoch 1980–86 where data covering the same period are available. The agreement between simulation and observation is improved when a parameterization of the snow surface redistribution processes, such as wind erosion, is included in the regional climate model. The modelled spatial distribution of the net snow mass transported in the boundary layer over coastal East Antarctica indicates that this mass is a significant component of the surface mass balance.

In the marginal areas of the Pleistocene Scandinavian ice sheet in north Germany there are few signs of direct glacial erosion. Fine gravel analyses show that glacial reworking was not very important. This may be partly due to the fact that at least in the late phases of the glaciation the active parts of the ice sheet moved over dead ice and were not in direct contact with the underlying substratum. Buried tunnel valleys with a depth of more than 400m show that considerable erosion by sub glacial melt-water streams took place, at least during the Elsterian glaciation.

During retreat from the lateWisconsinan maximum advance in the Great Lakes region of North America, the Laurentide ice sheet margin became distinctly lobate. The Lake Michigan, Saginaw, and Huron—Erie lobes converged in southern Michigan and Indiana, U.S.A. to form a complex interlobate region. Some time after the glacial maximum, the Lake Michigan lobe advanced over landscapes previously formed by the Saginaw lobe. This can be explained by an asynchronous advance of the Lake Michigan lobe during a Saginaw lobe retreat or by an increase in size of the Lake Michigan lobe relative to the Saginaw lobe during a synchronous readvance.

Cross-cutting relationships in southwestern Michigan, including palimpsest tunnel valleys, document the overriding of Saginaw lobe terrain. Deep, generally straight trenches parallel to glacial flow lines with hummocky, irregular sides and bottoms are interpreted as tunnel valleys. Saginaw lobe tunnel valleys trend northeast—southwest and Lake Michigan lobe tunnel valleys generally trend east—west.

At some time after a Saginaw lobe retreat in southern Michigan, the drumlinized landscape was overridden by an advance of the Lake Michigan lobe to an ice-marginal position at the Tekonsha moraine. Saginaw lobe tunnel valleys in the overridden area were completely filled with ice and debris from the Saginaw lobe retreat at the time of the Lake Michigan lobe advance. Supraglacial and proglacial sediments were deposited over the buried valleys by the Lake Michigan lobe, sometimes by meltwater streams that flowed at high angles to the trends of the valleys. After entrenchment of the Kalamazoo River valley, probably by a subglacial outburst flood, short tributaries were cut nearly at right angles across and through the debris and ice within several buried Saginaw lobe tunnel valleys. After the retreat of the Lake Michigan lobe, subsequent melting of ice in the palimpsest tunnel valleys exhumed the valleys, creating the cross-cutting relationships with the Lake Michigan lobe deposits.

In this study, long-term series of winter mass balances from two neighbouring glaciers in the southern Oetztal Alps, Austria, i.e. Hintereisferner and Vernagtferner, are analyzed with respect to the methods used in their determination. For this purpose, (1) some basic data of field surveys are presented, (2) the influence of different temporal systems is discussed, and (3) the profile, contour and a ‘model’ method based on energy-balance ablation modelling and measured net mass balance are discussed with respect to the reliability of the resulting series. The main findings of the investigations are: (1) The winter mass-balance series for Hintereisferner and Vernagtferner as determined with all applied methods result in a reliable climatologic average of 1000±100mmw.e. (2) When using the profile method, different spatial integration approaches are quite sensitive to the altitudinal coverage and the spatial pattern of observations. (3) The error of the model method occurs randomly, whereas contour as well as profile-method errors are more systematic. (4) Filtered time series from the two glaciers show similar tendencies for the last three decades.

In this paper an algorithm for ice/water classification of C- and L-band dual polarization synthetic aperture radar data is presented. A comparison of the two different frequencies is made in order to investigate the potential to improve classification results with multi-frequency data. The algorithm is based on backscatter intensities in co- and cross-polarization and autocorrelation as a texture feature. The mapping between image features and ice/water classification is made with a neural network. Accurate ice/water maps for both frequencies are produced by the algorithm and the results of two frequencies generally agree very well. Differences are found in the marginal ice zone, where the time difference between acquisitions causes motion of the ice pack. C-band reliably reproduces the outline of the ice edge, while L-band has its strengths for thin ice/calm water areas within the icepack. The classification shows good agreement with ice/water maps derived from met.no ice-charts and radiometer data from AMSR-2. Variations are found in the marginal ice zone where the generalization of the ice charts and lower accuracy of ice concentration from radiometer data introduce deviations. Usage of high-resolution dual frequency data could be beneficial for improving ice cover information for navigation and modelling.

During sea-ice formation, the dissolved constituents of water are rejected from ice crystals. the initial fractionation of dissolved organic matter (DOM) in the Baltic Sea ice was studied through two freezing experiments and by sampling natural sea ice. DOM was characterized by the spectral absorption of chromophoric DOM (CDOM) and the parallel factor analysis of DOM fluorescence. Molecular weight measurements of DOM were applied to assess changes in the molecular size distribution of DOM in new sea ice relative to parent sea water. Both in the newly formed artificial and the natural sea ice, CDOM was enriched by 34–39% relative to salinity. the same three identified DOM fluorophores were present both in sea water and ice but enriched by 15–54% relative to salinity in ice. After the incorporation of DOM into ice, the ageing of ice decreased the spectral slope coefficient and the molecular weight of DOM. This study shows that physical processes during freezing of brackish water enrich chromo- and fluorophoric DOM relative to salts in sea ice.

Measurements of summer and winter mass balances have been carried out over the past 53 years on Storglaciären, northern Sweden. Repeated surveys of the glacier have resulted in several maps of surface topography as well as a map of the bed topography A new time-dependent ice flow model allows us to compare the observed surface evolution of the glacier with that computed by the model using measured mass-balance maps as input. The computed volume change compares well with the measured change: the model replicates the distribution of surface elevation to within ±10 m over 30 years of integration. On the model side, these deviations can be attributed to the low-resolution discretization of the model domain as well as to the limited accuracy of the ice rheology and omitted basal sliding. On the other hand, the uncertainties of the topography and mass-balance maps match the model uncertainties. In this sense, the experiments are a validation of both model and observations.

We examined microorganisms and pollen in a pit (4.5m deep) and a shallow ice core (25.01m long) from Sofiyskiy glacier in the Altai mountains of Russia for potential use in dating ice cores from a mid-latitude glacier. The ice-core and pit samples contained various green algae, cyanobacteria, bacteria, fungi and pollen. In the vertical profiles of the pit, algal biomass peaks corresponded to high δ18O layers and Pinaceae pollen peaks, suggesting that these algae grew during the melt season. In contrast, the layer with the lowest δ18O contained almost no algal cells. Major peaks of the cyanobacteria, bacteria and a fungus roughly corresponded to those of the algae. However, seasonal changes in these microorganisms became indistinct deeper in the core, as did the seasonal variation in δ18O and major ions, most likely due to heavy meltwater percolation and/or post-depositional decomposition. In contrast, clear seasonal cycles were evident in the algal biomass and pollen in snow samples. Assuming that the peaks of the snow algae and Pinaceae pollen marked summer layers and that the layers with almost no snow algae represented the winter layers, we estimated that the ice core contained 16 annual layers (1985–2001). The mean annual mass balance for the period was estimated to be 1.01mw.e. The value agreed well with those estimated from stake measurements, indicating that snow algae and pollen could provide reliable boundary markers of annual layers in the ice cores of this region.