bluuebunny/crossref_metadata_2025 huggingface dataset:
Antarctic Ice-Shelf Boundaries and Elevations From Satellite Radar Altimetry
Authors: Zwally H.J. , Stephenson S.N. , Bindschadler R.A. , Thomas R.H.
Published: September 2017

As part of a systematic analysis of Seasat radar altimetry data to obtain Antarctic ice fronts and ice-shelf elevations north of lat. 72° S., Fimbulisen (between long. 12°W. and 08°E.) and the Amery Ice Shelf (around long. 72°E.) are mapped. Interactive computer analysis is used to examine and correct the altimetry range measurements and derive the ice-front positions. Surface elevations and ice-front positions from radar altimetry are compared with ice fronts, ice rises, crevasse zones, and grounding lines identified in Landsat imagery. By comparison of the visible features in imagery and the computer-contoured elevations from radar altimetry, the radar-elevation mapping on some ice rises is confirmed, but some spurious contours are also identified. During the interval between the 1974 Landsat imagery and the 1978 radar altimetry, the central part of the Amery Ice Shelf front advanced 1.5 ± 0.6 km/a, which is in agreement with the ice-velocity measurements of 1.1 ± 0.1 km/a (Budd and others 1982), suggesting negligible calving in the central part of the ice shelf. The undulating surface and small mean slope from the grounding line to about lat. 70°S. suggest a zone of partial grounding similar to Rutford Ice Stream, On Fimbulisen, some previously unmapped ice rises are identified. The ridge of the Jutul-straumen ice tongue is shown to be about 20 m above the surrounding ice and laterally expanding as it flows northward to the ice front. Icebergs within the sea ice and a zone of shore-fast ice are also identified with the same technique used to map the ice-shelf front.
Acoustical Reflection and Scattering from the Underside of Laboratory-Grown Sea Ice: Measurements and Predictions (Abstract)
Authors: Jezek K.C. , Stanton T.K. , Gow A.J.
Published: September 2017

We have studied acoustical reflection and scattering properties of the underside of laboratory-grown sea ice. Our purpose was to determine the morphologic characteristics of undeformed sea ice that control acoustic scattering and reflection. So our experiments included both detailed studies of the structure of the ice as well as the application of a variety of acoustic methods.

Ice sheets were grown in an outdoor pond (about 6 m by 13 m by 1.5 m) and exhibited features characteristic of undeformed, cold sea ice: an upper granular zone; a columnar zone of crystals with cross-sectional areas of about 1 cm2; vertical sheets of brine pockets; a bulk salinity of 9.1‰ distributed over 9 cm of ice; a dendritic interface at the ice/water boundary with dendrites about 0.5 mm across at the time of our measurements. Echo-amplitude fluctuations of normal-incidence sonar pings (100 kHz to 800 kHz) were measured as the sonars moved horizontally under the ice and accumulated into echo-amplitude histograms. (Data from a deteriorating ice sheet as well as data on lake ice were also collected.) We fitted the Rice probability density function (PDF) to the data and combined the resultant statistical parameter with Eckart acoustic scattering theory. The reflection coefficients calculated using this method ranged from 0.06 to 0.12, depending on environmental conditions. RMS roughness calculated using data from new sea ice was estimated to be about 0.3 mm. Because our ice thin sections show the ice to be porous and permeable at the interface with dendrites 0.5 mm thick, we suspect that the dendrites control the scattering as described by the echo-amplitude histograms. Further, we attribute the low reflection coefficients to the dendritic structure which may act as an impedance-matching zone into the columnar section of the sea ice.

Transmission measurements were performed by positioning a transducer located at the ice/air interface directly over the transducer located in the water. The total attenuation through 18 cm of ice ranged from 12 dB at 50 kHz to 70 dB at 420 kHz (signal levels were measured relative to the same path in water).
A Back-Portable Microprocessor-Based Impulse Radar System
Authors: Jones F.H.M. , Narod B.B. , Clarke G.K.C.
Published: September 2017

We have developed and tested a portable impulse radar for ground-based sounding of glaciers. Noteworthy characteristics of the instrument are its portability, low power consumption, digital data storage, and the ability to be operated either manually or automatically under program control. Current system specifications include a band width of 46 MHz; a sampling interval of 10.76 ns; depth precision of 0.9 m; 1024 samples per record; amplitude resolution of 8 bits; minimum recordable signal at the receive antenna equal to 0.26 mV; an operating center frequency of 8.5 MHz and an antenna-damping coefficient of 300 ohms.

The transmitter uses paired SCRs and a 12 V to 800 V converter to impress a 1200 V step on to a resistively damped dipole antenna. This pulse is triggered from the receiving system via a fibre optics cable so that each record can include the complete surface-path wavelet. The receiver unit combines a wide-band amplifier (with variable front-end attenuation) with a microprocessor-controlled data-acquisition system of our own design. The result of each sounding can be replayed as an “A-scope” display on a small, low-cost oscilloscope and stored on or retrieved from digital cassettes. In the unattended mode, records are collected at programmable intervals. The system weighs about 7.5 kg and uses dry cells or rechargeable batteries for power.

Examples were presented in a poster session of sounding profiles taken in July 1986 on Trapridge Glacier, Yukon Territory in Canada, along lines coinciding with an extensive drilling program. Although not yet fully analysed, we feel that some of the results may represent the effects of crevasses, internal features such as morainal material, varying bed features, and changes in subglacial and englacial hydrology.
Characteristics of Altimetry Signatures Over Sea Ice (Abstract)
Authors: McIntyre N.F. , Laxon S.W.
Published: September 2017

We report characteristics of Seasat altimetry signatures recorded over Antarctic sea ice. Up to four discrete zones can at times be seen in characteristic sequences in the Weddell and Ross Seas, and elsewhere. They are substantially larger than those reported in the Arctic, covering up to 2500 km at the time of maximum ice extent in 1978. Transitions between them can be abrupt, with marked changes occurring in less than a few kilometres. Some zones were found to persist through the 3 month satellite lifetime; others exhibited intermittent variations. Repeat data coverage has enabled temporal as well as spatial patterns to be investigated.

Interpretation of the geophysical cause of the patterns observed has been limited by available data. Some comparisons may be made with surface measurements of nadir back-scatter on first- and multi-year floes but these account for only a small proportion of the altimetry returns studied. Correlations with the NOAA Navy Ice Charts show significant disparities in the determination of the ice edge which may relate to the sensitivity of the altimeter to the presence of fresh ice or ice in very small quantities. Similar signatures can be found next to small coastal leads at the continental margin, an area known to be important for the growth of new ice.
Analysis of Simulated Radar Altimetric Wave Forms for Polar Ice and Snow Surfaces (Abstract)
Authors: Novotny Eva
Published: September 2017

The radar altimeter of the satellite Seasat has proved that ice and snow surfaces in the polar regions can return meaningful signals if the terrain is not excessively rugged or sloping. Because the use of the leading edge of the wave forms for height determination entails inherent uncertainties and, at best, provides only a single datum per wave form, the entire wave forms should be studied. Excesses or deficiencies in amplitude at various ranges within a single wave form, and the changes that occur in successive wave forms, can be analysed to yield information on the geometric and scattering properties of features observed by the altimeter.

Results from computer simulations are presented, showing how (1) a margin of sea ice (sinusoidal in the model) can be mapped, (2) the boundaries of two isolated ice floes can be outlined, (3) sea-ice concentrations can be derived within annuli about the nadir of an individual footprint, and (4) for land ice, the elevations of topographic features, together with the general slope of the ground, can be determined if an imaging instrument that operates simultaneously with the altimeter provides the outlines of these features. In examples (1) and (2), it is assumed that the ice is contiguous wherever that is possible, to permit the analytical reconstruction of the ice margin or individual ice floes in the presence of the inevitable ambiguity in the position of any feature with respect to the two sides of the satellite track. Example (4) requires that the altimeter record correctly records the strongest signals returned by ice-packs. This condition is not fulfilled by any existing radar altimeter, but it may be achieved in the next generation of these instruments. In additional examples of information from entire wave forms, the effects of crevasses and sastrugi in reducing or re-distributing the energy of the returned signals are also illustrated.

Full details of these analyses and results will be published at a later date.
Acoustic Emission Methods Applied to Avalanche-Formation Studies (Abstract)
Authors: Epifanov V.P. , Kuz’menko V.P.
Published: September 2017

The relationship between the intensity of snow acoustic emission impulses and snow-cover stability is revealed by measuring the physical and mechanical properties of the snow cover in the starting zones of avalanches. This relationship is fundamental to the remote identification of an avalanche-hazard period.

In order to estimate the mechanical properties of a snow layer, a method of applying a rigid penetrometer equipped with a piezoelectric accelerometer is used. The viscosity coefficients of snow under destruction and the specific energy of destruction are determined. The overall effect of the different elements of destruction is assessed using both structural investigations and acoustic methods (acoustic emissions).
Methods of Calculation and Remote-Sensing Measurements for the Spatial Distribution of Glacier Annual Mass Balances (Abstract)
Authors: Konovalov V.G.
Published: September 2017

The areal distribution of glacier annual mass balance b(z) is an important characteristic of the existence of glacierization and its evolution. At present the measured value of annual mass balance at different elevations is only available for a limited number of mountain glaciers of the globe, because of the great amount of labour required for such measurements.

The analysis of long-term mass-balance measurements made at Abramova Glacier, Limmerngletscher, White Glacier, Hintereisferner, and Peyto Glacier has revealed that for each year the spatial distribution of annual mass balance is well described by quadratic equations. The main variable in these equations is altitude (z). The various parameters of these formulae are estimated by the author for mean weighted height of the ablation and accumulation areas, and for the glaciers as a whole. It is found that the parameters of annual mass balance for each glacier can be calculated from formulae which include combinations of the following variables: annual balance at one of the three weighted altitudes, maximum annual snow-line elevation, annual and seasonal amounts of precipitation, and air temperatures at nearby meteorological stations.

Therefore, in order to calculate the distribution of annual mass balance as a function of absolute altitude, it is sufficient to obtain a value for mass balance measured only at a single point on a glacier, and common meteorological observational data. A comparison of actual and calculated values of mass balance has shown good agreement between them.

Considering the successful use of aerial remote-sensing for the measurement of snow depth in mountains by means of special stakes, it is satisfactory to accept this method for the assessment of annual mass balance at the mean weighted altitude of the ablation zone. It is possible to use aerial photo-surveys or stereophotogrammetry to resolve this problem. Then annual mass balance for the whole area of a glacier is calculated by using data from one point together with data from a nearby meteorological station.
An Experiment on Image Transmission to an Icebreaker (Abstract)
Authors: Korhonen O.
Published: September 2017

Finland has such a climate that all its harbours in the Baltic Sea are frozen every winter. Ice may sometimes be more than 1 m thick, as it was in the Bay of Bothnia, the northernmost basin of the Baltic Sea, during the winter of 1985.

The Finnish Institute of Marine Research has used the imagery of the Tiros-N series of satellites successfully in sea-ice mapping for some years. In the Institute daily ice charts have been prepared and sent by facsimile to icebreakers in the Baltic Sea. In 1985, an experiment was conducted to transmit the same imagery to an icebreaker operating in the Bay of Bothnia. Existing telecommunication networks were used. The image data transmitted by NOAA-6 and NOAA-9 satellites were received at Tromsø Telemetry Station in Norway and then transmitted to Espoo in Finland. The data processing consisted of geometric correction, edge enhancement, and drawing the coastline with location symbols. The most interesting area was extracted and transmitted by NMT mobile telephone to the icebreaker.

The almost real-time image transmission turned out to be useful from the point of view of icebreaker operation. The images could be used to identify cracks and narrow leads in the ice. Such very detailed information cannot be included in routine ice charts. The icebreaker can use this information for giving instructions to other ships to find easier routes. This reduces the need for icebreaker assistance. The images can also help the icebreaker to avoid wide heavily ridged areas.

This experiment was at low cost and can be technically developed further. It showed that this kind of assistance for icebreakers is economically profitable for winter navigation.
Methods for Snow Mapping from Meteorological Satellite Imagery of the Qilian Mountains, North-West China (Abstract)
Authors: Liu Z.K. , Chang S.Y.
Published: September 2017

A snow survey in north-west China has been carried out using meteorological satellite NOAA-9 imagery. A two-step geometric correction method is presented. The first step involves a large-scale geometric correction, and the second step concentrates on a small area of interest, using the control-point correction method. A high precision of geometric correction can beachieved by using this method. The snow-covered area of the Qilian Mountains basin is calculated.
Remote Sensing of Fast Ice in Lützowholmbukta, East Antarctica, using Satellite NOAA-7, 8 and Aircraft (Abstract)
Authors: Mae S. , Yamanouchi T. , Fujii Y.
Published: September 2017

Lützowholmbukta, East Antarctica, is covered by fast ice except during a short period in April and May, but occasionally the ice cover breaks up and floats out of the bay.

The fast ice was observed every day using NOAA-7, 8 infra-red imagery. The satellite signal was received at Syowa Station, located on Ongul Island. In addition, aerial photographs and video pictures were taken using aircraft every fortnight.

In 1983, before the break-up of the fast ice in April, a distinctive increase of the infra-red radiance (NOAA AVHRR) was observed, even though the aerial observation showed no change. The increase of the radiance was estimated to be 5°C. It was in this area, where the higher infra-red signal was observed, where the fast ice broke up. In December, in the central part of the northern area of the fast ice, the hummock-ice zone formed in a triangular shape. Before the hummock-ice zone floated out, observation of the infra-red radiance showed that the temperature of the ice had decreased by 3°C.
Estimation of Snow-Melt Run-Off During Pre-Monsoon Months in Beas Sub-Basin using Satellite Imagery (Abstract)
Authors: Sharma K.P. , Garg P.K.
Published: September 2017

The increasing demand for water, coupled with the construction of multi-purpose reservoirs to control and regulate snow-melt run-off, requires accurate strearm-flow forecast. For making an accurate prediction of spring run-off, information on the amount of snow accumulation in winter is necessary; this may be achieved through remote-sensing techniques in any inaccessible region.

This paper outlines the snow-melt run-off study carried out in a part of Beas basin, India, using Landsat imagery for the years 1973, 1975, 1976, and 1977. The Beas basin lies between long. 76°56' to 77°52'E. and lat. 31°30' to 32°25'N., covering an area about 4900 km2, of which 1400 km2 is permanently covered by snow. The gradual melting of snow accumulated over the catchment area during the winter months is responsible for the perennial character of the Beas River.

Photohydrological investigation of the part of the Beas basin up-stream of Barji was carried out and a study was made for the estimation of the snow-melt run-off during the pre-monsoon period in the sub-basin up-stream of Manali. For this purpose, the sub-basin has been divided into permanent and temporary snow-covered zones. The degree-day method and the melt due to rainfall on snow have been used to estimate snow-melt run-off. The routing of snow-melt, after accounting for losses as well as the run-off from the excess rainfall from the permanent and temporary snow-covered areas, has also been done taking the recession coefficient K as 0.90, and the excess rain from the non-snow-covered areas has been assumed to contribute directly to the run-off for that day. Run-off coefficients of 0.595 for rainfall on the snow-covered areas and 0.278 for rainfall on the non-snow-covered areas have been determined.

Reference can be made to similar work in India and Pakistan to establish the relationship between the snow cover and the cumulative discharges for the months of March, April, and May of the years 1973, 1975, 1976, and 1977, and an exponential trend was observed with the help of Landsat Imagery. Furthermore, the snow-covered areas as determined from bands 5 and 7 of the Landsat imagery, for the same day, showed a linear trend.

The analysis of the results shows that remote-sensing data used in conjunction with conventional methods are likely to improve the accuracy of the snow-melt forecasts in remote areas like the Himalayan catchments.
Inter-Relations between the Arctic Sea Ice and the General Circulation of the Atmosphere (Abstract)
Authors: Wendler G. , Jeffries M. , Nagashima Y.
Published: September 2017

Satellite imagery has substantially improved the quality of sea-Ice observation over the last decades. Therefore, for a 25-year period, a statistical study based on the monthly Arctic sea-ice data and the monthly mean 700 mbar maps of the Northern Hemisphere was carried out to establish the relationships between sea-ice conditions and the general circulation of the atmosphere. It was found that sea-ice conditions have two opposing effects on the zonal circulation intensity, depending on the season. Heavier than normal ice in winter causes stronger than normal zonal circulation in the subsequent months, whereas heavier than normal ice in the summer–fall causes weaker zonal circulation in the subsequent months. Analyzing the two sectors, the Atlantic and Pacific ones separately, a negative correlation was found, which means a heavy ice year in the Atlantic Ocean is normally associated with a light one in the Pacific Ocean and vice versa.
Photo-Interpretation, Digital Mapping, and the Evolution of Glaciers in Glacier National Park, B.C.
Authors: Champoux André , Ommanney C.S.L.
Published: September 2017

The inventory of Glacier National Park, B.C., has provided an opportunity to test a number of new procedures which might be applied to future Canadian glacier inventories. The objectives of this particular study were to complete a tripartite inventory based on available map and photo sources and develop an automated system of data acquisition and processing. The conjunction of the two has permitted an analysis of the evolution of the glaciers in this area during the last 100 years. The techniques used and a summary of the results are reported.
Map of the Mount Gongga Glacier: A Combination of Terrestrial and Aerial Photogrammetry
Authors: Jianming Chen
Published: September 2017

For use in glaciological research, between 1982 and 1984, we succeeded in surveying and mapping the Mount Gongga Glacier, on a scale of 1:25 000, by means of a combination of terrestrial and aerial photogrammetry. This paper describes the method in detail.

In the survey area, we set up an independent, triangulation network, with microwave distance measurement, and two, independent, straight-line traverses, for basic control. Control points were observed by intersection. The terrestrial, photogrammetric baselines were projected and corrected into distances on the. plane of the map.

Terrestrial photography accounted for the majority of the photographs of the survey area. Surveying and mapping of planimetrie and topographic features were completed on a stereo-autograph, using plates mainly from terrestrial photogrammetry. Where these data were insufficient, they were supplemented by aerial photography, plotted on a photographic plotting instrument. Orientation points of the aerial photographs were established by terrestrial, photogrammetric analysis and located on the map by an optical, mechanical method.

The practical result showed that a combination of terrestrial and aerial photogrammetry, in mapping a high, mountain, glacier area, on a large scale, is more feasible and flexible than other methods and more economical as well.
Least Squares Method Used in Reduction of Data From Theodolite Measurements on Fast Moving Glaciers
Authors: Dahl-Jensen D. , Steffensen J.P. , Johnsen S.J.
Published: September 2017

A statistical method to determine surface velocities from theodolite measurements is described. The method assumes that the measuring points move according to a model and the model parameters are estimated directly from the directional observations. Observations from two fixed points need not be simultaneous, which is an advantage in the case of fast moving glaciers. The method is practised on data from the Daugaard-Jensen glacier, in East Greenland, where the motion of the measuring points is calculated to the accuracy of the directional observations.
Digital Mapping of the Nordaustlandet Ice Caps from Airborne Geophysical Investigations
Authors: Dowdeswell J.A. , Drewry D.J. , Cooper A.P.R. , Gorman M.R. , Liestøl O. , Orheim O.
Published: September 2017

Airborne geophysical investigations of the previously tittle-studied Nordaustlandet ice caps (11 150 km2) took place in 1983, using SPRI 60 MHz radio echo-sounding (RES) equipment of 160 dB system performance. RES and navigational data were recorded digitally. Navigation used a ranging system (accurate to ±30 m) from aircraft to ground-based transponders, located by satellite geoceivers, supplemented by the aircraft’s navigational instruments and timed crossings of known features. Ice surface and bedrock elevations were measured, using aircraft pressure altitude, terrain clearance, and ice thickness data. The mean error of 251 crossing points on Austfonna was 11 m. The reduced geophysical data are stored on a direct-access computer database. During 3400 km of flying, Austfonna (8105 km2) was covered by traverses a nominal 5 km apart, whereas a 15 km-spaced grid was flown over Vestfonna (2510 km2). Maps of ice surface morphology and subglacial, bedrock topography were produced for Austfonna and Vestfonna, along with an ice thickness map of Austfonna, Austfonna reaches a maximum surface elevation of 791 m and ice thickness of 583 m. 28% of the bedrock area beneath Austfonna lies below sea level. RES yielded bedrock echoes for 91% of track over Austfonna, but only 52% over Vestfonna. This was probably due to warmer conditions on Vestfonna, resulting in greater absorption and scattering of electro-magnetic energy. Ice surface elevations are a principal data source in the revision of official Norwegian maps of Nordaustlandet.
Glacier Mapping to Confirm Results from Mass-Balance Measurements
Authors: Haakensen Nils
Published: September 2017

Annual mass-balance measurements have been made at a number of glaciers in Norway since the beginning of the 1960s, A detailed and reliable map is necessary as a base for field work and more than twenty glacier maps have been constructed photogrammetrically at scales of 1:10 000 or 1:20 000 since 1952. For some of the glaciers more than one map has been constructed and changes in glacier volume can be calculated, provided the maps have sufficient accuracy.

For the glaciers, Nigardsbreen, Hellstugubreen, and Gråsubreen, two or more good maps are available and these form a good basis for comparisons and calculations of changes in volume between the years when the air photographs were taken.

Comparisons have been made for Gråsubreen between 1968 and 1984, for Hellstugubreen between 1968 and 1980, and for Nigardsbreen between 1964 and 1984.

The calculations are made by placing a 100 m grid on the glacier maps and comparing the altitude for corresponding points. The changes in height are regarded as representative for the 0.01 km2 glacier areas represented by each point.

Results from the investigation have been used to check the accuracy in cumulative mass balance for corresponding periods.

Repeated air photography, at intervals of 5—10 years, can be used in the future to find the cumulative mass balance for a great number of glaciers at lower cost than “normal” mass-balance work.
Main Results of Mapping Glacio-Nival Systems in the World Atlas of Snow and Ice Resources
Authors: Kotlyakov Vladimir M. , Dreyer Natalia N. , Kravtsova Valentina I.
Published: September 2017

The compilation of the Atlas was based on the concept of glacio-nival systems (and the fields of these systems), developed in the U.S.S.R. It became possible to map glacionival systems by using all available data and by the development of indirect methods of obtaining regime parameters, characterising the glacio-nival zones. This, in turn, made it possible to show, on maps of different scales, properties relating to glacio-nival phenomena and processes, such as air temperature in a glacierized zone, the amount of solid and liquid precipitation, snow storage, the accumulation and surface ablation of glaciers and melt run-off.

The compilation of these maps has demonstrated their conformity and complementary nature, the principles of which were worked out in the course of creating the Atlas.

Based on the experience of compiling hundreds of various maps, the paper describes some peculiarities of depicting different elements of glacio-nival systems on maps of different scales and shows ways to overcome shortages of data in preparing the maps.
Antarctic Ice-Sheet Topography and Surface-Bedrock Relationships
Authors: McIntyre N.F.
Published: September 2017

Mapping the topography of the Antarctic ice sheet has confirmed that there is, typically, a decrease in the wavelength and increase in the amplitude of surface undulations with distance from ice divides. This pattern is distorted by converging ice flow in coastal regions and by other variations in subglacial relief, ice velocity, and viscosity. The near-symmetry of undulations indicates the extent of three-dimensional flow over bedrock peaks. Spectral analyses indicate the greater response of the ice sheet to bedrock features with longer wavelengths. This is affected, and in some cases dominated, by the inhomogeneous and non-isothermal nature of the ice sheet.
Repeated Glacier Mapping for Hydrological Purposes: Water Power Planning
Authors: Østrem Gunnar
Published: September 2017

Good hydrological knowledge is necessary for the planning of a hydro-electric power installation. Observations of daily discharge in Norwegian streams are available for several decades, but for glacierized basins there is a lack of information. Either the observation period is too short or it comprises mainly years when glaciers retreated and thus produced extra amounts of melt water – a direct result of negative mass balance. Consequently, many discharge figures are too ‘optimistic” — they indicate larger average run-off than would be the case if glaciers were in a steady state, or, even worse, if they started to grow and then started to reduce their melt-water contribution to rivers.

Our means of correcting actually observed discharge figures for glacier influence is to perform annual mass-balance measurements. This has been done since 1948 for one glacier and since 1962 for several glaciers and results have been used in the planning of power stations. The method is, however, relatively costly.

Another method is now being developed. Repeated glacier mapping makes it possible to calculate the average change (decrease) in glacier volume between the years when air photographs were taken. Therefore, several glacier maps have been produced based upon older vertical photographs and new maps are constructed from repeated air photography of the same glaciers. By subtraction, the total decrease in ice volume can be calculated and, hence, corrections of observed discharge be made.

This method is quicker and cheaper than conventional mass-balance measurements. Large potentials for this method lie in future digital maps.

Almost all the detailed (1:10 000) Norwegian glacier maps are printed in four colours and they have a standard UTM coordinate grid and 10 m contours. An example of a recent map is enclosed in the map pocket on the rear cover of this volume.
Ice Divide Migration at Blue Glacier, U.S.A.
Authors: Waddington E.D. , Marriott R.T.
Published: September 2017

A 1984 strain net on the Snowdome of Blue Glacier showed that the surface slope is a good estimator of ice flow direction and divide location. Topographic maps from 1939, 1952, 1957, 1979, and 1984 show that the flow divide migrates within a zone up to 350 m wide, in response to changes in east-west gradient in snowfall. This zone encloses 6% of the Blue Glacier accumulation area and up to 10% of the year-end residual snow. An ongoing 28-year mass-balance study has used an extreme, westerly divide, giving systematically high net balance estimates. The correct catchment area, for a given balance year calculation, depends on the future migration sequence of the ice divide, with a time constant of about 30 years.
Cartographic Methods for Large Scale Glacier Maps
Authors: Shicong Yin , Jianming Chen
Published: September 2017

Glacier mapping is steadily developing, along with the continuous expansion of glaciological research, in China. In the last 20 years we have made surveys and drawn up glacial topographic maps on large scales, of various study areas in Tianshan and the Qinghai-Xizang Plateau. This paper discusses the cartographic techniques, in the form of points, lines, symbols, brush-shading, colours, etc., used to create a vivid reproduction of the special natural landscape of glaciers on maps for the use of glaciologists and other scientists. For example, variations in rock symbols may be used to show the exposed bedrock, the glacial abrasion and the cryogenetic weathering. Different colours and points are used to indicate the various depositional landforms which are also enhanced by the method of brush-shading and the use of differently coloured contour lines. In addition, the paper discusses the technical and theoretical problems of glacier mapping.
Surface Topography of the Greenland Ice Sheet by Satellite Radar Altimetry (Abstract)
Authors: Bindschadler R.A. , Zwally H.J.
Published: September 2017

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).
Preliminary Evaluation of Landsat 4 & 5 Data of Antarctica (Abstract)
Authors: Ferrigno Jane G.
Published: September 2017

Landsats 4 & 5 have acquired approximately one thousand images of Antarctica in 1984 and 1985, including a few thematic mapper images. I will show, on two maps, where these images have been acquired and give a preliminary evaluation of their quality.
Ice Streams and Grounding Zones of West Antarctica and the Ross Ice Shelf (Abstract)
Authors: Shabtaie S. , Bentley C.R.
Published: September 2017

In 1984-85, airborne radar soundings were carried out over West Antarctic ice streams A, B, and C, the neighboring parts of the Ross Ice Shelf, and Crary Ice Rise. Here we use the radar data to map the boundaries of the ice streams, to calculate surface elevations, and to measure ice thicknesses. Lee thicknesses and surface elevations have been used together to map the grounding zones and ice rises (Figure 1).
New Frontiers of Seismic Surveying in Antarctica: The Mapping of A Thin Layer at the Base of Ice Stream B (Abstract)
Authors: Blankenship Donald D.
Published: September 2017

The recent availability of high resolution (greater than 250 Hz) seismic recording equipment in the Antarctic field environment has allowed the acoustical mapping of a previously unobserved subglacial phenomenon. This phenomenon is a thin (less than 10 m), yet continuous, layer at the base of Ice Stream B in West Antarctica. Discovery of this layer came during the 1983–84 austral summer in a seismic reflection survey that covered approximately 10 km2 near the Upstream B field camp (83°31’S, 138°05’W). Although analysis of the seismic data is at a preliminary stage, there is the possibility that this feature could be a basal “lubricating” layer; some sort of lubrication is of course necessary to explain the very large horizontal velocities of these ice streams.

During the seismic reflection survey on Ice Stream B, a new digital seismic recording system, developed by the Geophysical and Polar Research Center, was used for the first time under field conditions. Resolution of such a thin layer was possible only because of the very large bandwidth (0–600 Hz) and dynamic range (84 dB) of this device; this bandwidth is about twice that possessed by commercially available seismic recorders. In addition, a new level of portability (i.e. a weight of 40 kg and a power requirement of 90 watts), which should make this device usable in virtually any Antarctic field situation, has been achieved by the application of advanced recording technologies. The portability of this digital seismic recorder, when combined with its large bandwidth and dynamic range, should result in the resolution of a whole new class of intra- and subglacial phenomena, of which the thin basal layer of Ice Stream B is the first example.
Compilation of Glacier Maps for Some Mountains (Abstract)
Authors: Pei Gu , Jueying Bu
Published: September 2017

Chinese Glacier Inventory is part of International Glacier Inventory, and glacier maps are important components of the glacier inventory.

Since 1979, we have completed glacier maps for Qilianshan, Altaishan, Tianshan and Pamier mountain systems one after another, about 40% of the whole work.

In order to improve the quality and accuracy of the maps, we fully considered the principles for the compilation of the International Glacier Inventory with due respect to the specific conditions in China as follows;

1.

Materials and data.

Newly published aerial topographic maps of 1:50 000 and 1:100 000 are used as basic maps with aerial photographs as supplementary data for checking and correction.

2.

Scale and projection.

According to the use of the glacial maps, the shape and size of the surveyed area and base data, the scale of the maps of drainage basins is fixed at 1:250 000 and 1:400 000, with Gauss projection. For the distribution maps of glaciers and their geographic landscape and characteristics, and for coding key maps, scales of 1:1 000 000 and 1:2000 000 are used, respectively, and their projection is the normal, minimum-error, conformal, conical projection, with two standard parallels.

3.

Synthesis and presentational method.

To show the location, type, shape, direction of movement and dependent drainage basin of glaciers is the most important task for the compilation of glacier inventory. Therefore, it is very necessary to carry out scientific summarization during compilation and to decide the acceptance or rejection of the surveyed features. In addition, the key elements of drainage basins, ridges, etc. are also given in detail.

The glacier map is a basic skeleton for the glacier inventory, giving important basic data for glaciological research and exploitation, as well as the utilization of the ice-snow resources, etc.
Glaciological and Hydrological Map of the Hornsund Fiord Area: 1:75 000 (Abstract)
Authors: Jania J. , Pulina M.
Published: September 2017

The problem of how to select and synthesize glaciological and hydrological information for the map of South Spitsbergen is discussed. The area of interest covers aproximately 1700 km2, but not all of it has been explored equally well so far. The map is under preparation for printing. It is one of a series of environmental maps of Hornsund at 1:75 000. Geomorphology and geology have been completed already. The general objective was to reveal the spatial differentiation of glacial and hydrological phenomena in the vicinity of the Hornsund Fiord but particular interest was focused on providing synthesized information about glacial and hydrological phenomena and processes, which had been considered in the context of natural hydrological basins.

The result is a specification of the phenomena represented in the map. It had been divided into five parts;

(1)

elements of geomorphology, geology (lithology) and topography (basemap);

(2)

features of glaciers and glacial phenomena on land;

(3)

physical and chemical properties of on-land streams and glacier streams;

(4)

features of marine environment and Hornsund Fiord bottom (during contruction); and

(5)

general characterization and classification of phenomena occurring in hydrological basins.

The first is of a general nature. Parts two, three and four include detailed, analytical information. Part five comprises synthesized data.

The glaciers of Hornsund are specified by morphological classification, according to PSFG of the IAHS, by the position of the mean firn line and major glacier zones, and by the pattern of the ice flow-lines, along with some information on the velocity of flow. Thermal classification of the glaciers, and data on the oscillations of the glacier fronts in the 20th century are presented.

Of the Hornsund glaciers, Werenskioldbreen (approximately 27 km2)has been exposed in the map at 1.25 000. It has roused the interest of many investigators and is amongst the best explored examples. The available set ot data pertaining to this glacier consists predominantly of analytical, quantifying information, e.g. on the changes of the glacier surface altitude which occurred from 1957 to 1983, on the net balance at selected points of the glacier, on the pattern of englacial and subglacial channels, on the discharge in glacial streams, and on the quantity and degree of mineralization and chemical content of glacial streams, etc.

The result is a coloured map which aims at representing, in a systematic and synthesized manner, contemporary phenomena and processes associated with the glaciers and the water system of the Hornsund Fiord basin.
A Numerical Ice-Stream Model: Application to Holocene Retreat in the Ross Sea, West Antarctica (Abstract)
Authors: Linglet Craig S. , Clark James A.
Published: September 2017

A numerical model of ice-stream retreat during the Holocene period of rising sea-level has been constructed, and applied to one of the ice streams draining the Ross Sea sector of the West Antarctic ice sheet. The purpose of the experiment is to assess the relative significance of eustatic sea-level rise, the response of the solid Earth to the changing ice load, and the formation of the Ross Ice Shelf on retreat of the ice-stream grounding line to its present position in the Ross embayment. An underlying hypothesis is that marine ice sheets (such as that in West Antarctica), the ocean, and the solid Earth form a coupled dynamic system in which changes, once initiated by an external event such as rising sea-level, can proceed independently of climatic change. Ice stream E (see maps by Rose 1979) was used as a test case during development of the model.
Tides, Tidally Driven Barotropic Circulation and the Formation of Tidal Fronts Below the Ross Ice Shelf, Antarctica (Abstract)
Authors: MacAyeal Douglas R.
Published: September 2017

Ocean circulation and heat transport below the Ross Ice Shelf are difficult to observe because of the thick ice cover. Numerical modeling thus provides a practical method for testing ideas about sub-ice-shelf circulation and basal melting. In this study, tidal rectification (Zimmerman 1981), tidal front formation (Fearnhead 1975), and their impact on the sub-ice-shelf environment are determined from a numerical tidal model.
A Time-Dependent Simulation of the Ross Ice Shelf Flow (Abstract)
Authors: MacAyeal Douglas R. , Thomas Robert H.
Published: September 2017

The finite-element model discussed by MacAyeal and Thomas (1982) has been improved to include solution of the heat equation within each element, and to accelerate convergence to solution of the momentum-balance equations in terms of ice-shelf spreading rates. The model is now sufficiently rapid to permit both snapshot and time-marching simulations of a large ice shelf at high spatial and temporal resolution (grid size 10 km; time step 0.1 a). Here, we describe three model simulations of Ross Ice Shelf behavior.
The IGS Symposium on Ice and Climate Modeling: An Overview
Authors: Radok Uwe
Published: September 2017

The Symposium on Ice and Climate Modeling was staged by the International Glaciological Society (IGS) with the co-sponsorship of the American Meteorological Society to bring glaciologists into direct contact with modelers of the Earth’s climates during interglacials (such as the present) and glacial episodes. The purpose of mutual familiarization was served by reviews of the hierarchies which now exist for models of atmosphere, ocean, and climate. These reviews emphasized the actual or potential uses of ice data and parameterizations, and both general and specific aspects of coupling and sensitivity testing. The glaciologists in their turn reviewed the problems of exploring different ice forms and simulating their responses to climatic forcing. Interspersed with the didactic presentations important new results were reported. The most significant concerned atmospheric concentrations of carbon dioxide deduced from ice core analyses, which were put into a wider context by a new interpretation of the ocean as a chemical system.

The presentations and discussions highlighted a wide range of problems ripe for collaborative study. Topics recommended for priority attention include contemporaneous changes in the properties of ice cores from Greenland and Antarctica, links between weather sequences and the stable isotope contents of polar precipitation, systematic intercomparisons of a wide range of model results, and the construction of intermediate-complexity sea-ice models for use in climate simulations.
Field Test 1 of Compressive Strength of First-Year Sea Ice
Authors: Sinha N. K.
Published: September 2017

A test program undertaken in April 1981 on the uniaxial compressive strength of freshly recovered first-year columnar-grained sea ice at a portable field laboratory floating on top of the ice cover in Eclipse Sound, Baffin Island, Canadian Arctic, is reported. Using a small battery-operated test machine, both vertical and horizontal samples were tested so that the load could be applied either parallel or perpendicular to the axis of the columns. Rate sensitivity of the observed strength is discussed in terms of measured average strain-rate and average stress-rate to upper yield or failure. Strain and time aspects of the test results are considered as well. Although vertical samples showed considerably greater strength than horizontal samples, no significant differences were detected in the failure strains. Examination of the interdependence of failure stress and failure time revealed certain anomalies in the results for vertical samples that could be linked to the performance characteristics of the test machine. As such problems could be common to any test system, methods of analysis are proposed for rational examination of the results.