bluuebunny/crossref_metadata_2025 huggingface dataset:
Formation Processes of Ice Fabric Pattern in Ice Sheets
Authors: Azuma N. , Higashi A.
Published: September 2017

Experimental studies on the Formation process of the single maximum fabric of ice from its random fabric were carried out using both Greenland Dye-3 ice cores and artificially grown polycrystalline ice. From the observations of the rotation of c-axes of individual grains in thin specimens, an empirical equation was obtained for describing the rotation process of c-axes. Combined with another empirical equation on the relationship between the uniaxial strain of whole specimen and the uniaxial strain in individual grains of different c-axis direction, an equation was derived which describes the formation of single maximum fabric in bulk ice samples.

Computer simulation of the formation process was performed based on an equation starting from an artificially made random fabric pattern. From the results obtained by a stepwise simulation of 2% strain intervals, the degree of concentration expressed by θm, the angle which halves the number of grains in the fabric diagram is correlated with the accumulated strain in bulk ice (Fig. 8). The strain deduced by applying this relationship to the obtained θm for samples of Dye-3 ice core coincided well with actual strain which the samples had experienced. This implies that the equation is valid and the mechanism of c-axis rotation prevails in polar ice sheets.
The Effect of Roughness on the Rate of Ice Accretion on a Cylinder
Authors: Makkonen Lasse , Stallabrass J. R.
Published: September 2017

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

Comparisons with empirical data show that the model simulates well the overall heat transfer rate from the front half of a cylinder with distributed roughness. The theory provides improved agreement between the results of a numerical icing model and icing wind tunnel tests.
Heat Balance at the Snow Surface in a Katabatic Wind Zone, East Antarctica
Authors: Ohata Tetsuo , Ishikawa Nobuyoshi , Kobayashi Shun’ichi , Kawaguchi Sadao
Published: September 2017

Each component of the heat balance equation was obtained independently for 24 days in winter and 8 days in summer in 1980 at Mizuho station, East Antarctica. In winter, net radiation QNR was -37.6W/m-2 , QS; +36.7W/m-2 and QC; +2.5W/m2 QL was three orders less than QS. In the summer, QNR; +l9.9W/m-2 QC;-7.4W/m’, QL ; -.SW/m-2 and Q C; .2W/m-2. In the winter cloud amount was an important factor determining the variation in heat balance components, but also variation in the strength of the katabatic wind had effect. Condensation of water vapor occurred in winter and sublimation in summer: summer sublimation had a significant effect on the heat balance. The small condensation may be due to the structure of the temperature inversion at Mizuho which is related to the katabatic wind. The present results show that at Mizuho, the radiation loss Q NR and Q S which compensate it is larger than at any other site on the continent excluding the coastal stations.
Snow Stratigraphy Measured by an Active Microwave System
Authors: Fujino Kazuo , Wakahama Gohow , Suzuki Masahiro , Matsumoto Tadashi , Kuroiwa Daisku
Published: September 2017

Snow stratigraphy was obtained in the laboratory and field, using a FM-CW radar system having microwave frequencies ranging from 2-8 GHz and from 6-12 GHz. A multi-layered model consisting of artificial snow such as glass beads or polystyrene plastics was used in the laboratory. In the field, the thickness of an individual layer within a snowpack was determined by analyzing the profile of responses from interfaces within the snowpacks. Large anomalies of the responses which produce misleading results, were found to have been caused mainly by multi-reflection between stratified layers as well as residual mismatch reflection in the system’s components.

The physical properties of a snowpack were measured by digging a snow pit. The comparison of the microwave responses in the profile with the visual stratigraphic layering of snow was made by inserting a reflection plate between individual layers within the snowpack,
Experimental Study on Direct Shear Strength of Sea Ice
Authors: Saeki Hiroshi , Ono Toshiyuki , Zong Niu En , Nakazawa Naoki
Published: September 2017

When structures such as oil drilling rigs are constructed on or through the ice plate in coastal and offshore regions, the shear strength of sea ice must be estimated to determine the loading on these structures. Testing methods for shear strength must be established so that shear strength of sea ice in various conditions can be determined.

The authors have been conducting, for five years, direct shear strength experiments using sea ice samples from the Okhotsk Sea coast. Physical characteristics of sea ice, including shear strength, depend to a great extent on such properties as salinity, porosity, grain size, etc; thus, there is variation in the test results of five years experimentation since the samples obtained varied from year to year.

The following conclusions were drawn from this experiment:

i)

Under certain conditions the relation between shear strength and vertical stress can be represented by Coulomb’s equation of soil; ie,

where Ts: shear strength, C* : apparent cohesion (shear strength at σv σv = 0), φ*: angle of internal friction, σv : vertical stress

ii)

The shear strength of sea ice increases, approaching a constant, with decreasing ice temperature.

iii)

The shear strength decreases with increasing ice shear area; an analogous relation exists in concrete.

iv)

The shear strength is not greatly dependent on either the shear velocity or stress rate.

v)

The shear strength is greater and generally increases more rapidly with decreasing ice temperatures in planes perpendicular to the ice growth direction than in planes parallel to it.

vi)

Two types of failure occurred in the sea ice samples. In the case of (sample diameter)/(sample length) less than 2 , the failure was induced by shear only. With d/l>2, the failure was not solely caused by shear since the existence of a small gap between the ice sample and shear box introduced a bending moment.
Katabatic Snow Storms in Stable Atmospheric Conditions at Mizuho Station, Antarctica
Authors: Kobayashi Shun’Ichi , Ishikawa Nobuyoshi , Ohata Tetsuo
Published: September 2017

This paper describes the results of snow drift measurements made on a strong katabatic wind slope at Mizuho Station (70°42.6’S, 44°18.9’E; 2230 m above mean sea level) in East Antarctica. From the vertical profile of the mass flux of blowing snow up to 28 m above the snow surface under conditions of snow fall, the snow fall densitities have been estimated as asymptotes of the profile (Fohn 1980). Snow fall densities as asymptotes were estimated between 8x10-6 and 8xl0-5 kg/m3. Assuming a fall velocity of blowing snow particles as 0.5 m/s, above values correspond to values of the vertical flux of snow fall between 2x10-3 and 1.5xl0-1 mm/h.
Comparison of Ice Crystals Grown from Vapour in Varying Conditions
Authors: Yamashtta Takira , Asano Asaharu , Ohno Takayuki
Published: September 2017

In a static supercooled cloud dendrites hardly grow at about -15°C except at the pointed tip of a needle-like ice crystal or an isolated thin plate-like ice crystal. When ice crystals are moved slowly in a static supercooled cloud, dendrites grow at about -15° C and the α-axis growth rate increases as the velocity of the dendrites increases; at velocities higher than 20 cm/s, however, the a-axis growth rate decreases as the velocity increases due to the influence of heavy riming. The maximum a-axis growth rate in a supercooled cloud is observed at about -15°C in experiments growing ice crystals in free fall.
Release Mechanism of an Avalanche on a Slope Covered with Bamboo Bushes
Authors: Endo Yasoichi
Published: September 2017

The glide of a snow cover on a slope covered with bamboo bushes was simulated so that the bushes’ resistance to glide was quantitatively related to the glide distance and speed. In one case their stalks and leaves were kept in the snow without falling down, in a second case they fell down and lay under the snow. Using the relations obtained, a description was given as to the behavior of a snow cover on a uniform slope as well as the distribution of stress and glide speed immediately before crack formation. Then, a criterion of crack formation was given in terms of glide speed.
Fluctuations of Sedimentary Environments of the Gyajo Glacier, Khumbu Region, East Nepal
Authors: Fushimi Hiroji , Kamiyama Koukichi , Kitaoka Kouichi , Ikegami Kouichi
Published: September 2017

Studies on the snow-layer stratigraphy were carried out at the Gyajo glacier, Khumbu region, East Nepal from 1973 to 1978. The ages of the snow layers were determined by stratigraphy and tritium analyses, and the fluctuations of sedimentary environments of the Gyajo Glacier, the lower type of a glacier located below 6,000 m in the Nepal Himalayas, were clarified from 1940s to 1975 in relation to the climatic changes. The results are: (1) It is likely that one snow layer per year is preserved divided by dirt bands: there are depositional periods ranging for 4-9 years, interrupted by depositional gaps (lacuna) lasting several years. Such stratifications contrast with such higher glaciers as the Khumbu Glacier, where two snow layers per year are formed with continuous deposition. (2) The ages of snow layers were determined by variation of tritium concentrations due to the thermonuclear tests series of 1950s-1970s. From 1940s to 1960s, the net annual balances have a decreasing trend from 450 to 45 mm, while annual balances are relatively large at the start of the 1970s, ranging from 540 to 270 mm, due to the increased precipitation.
Structure and Falling Motion of Early Snowflakes
Authors: Kajikawa Masahiro
Published: September 2017

Relations between the structure and falling motion of early snowflakes, ie those composed of a few crystals, were investigated to clarify their growth process.

The following results were obtained: (1) Two crystals of the same shape in a snowflake are similar in size, but those of different shape are considerably different in size. (2) In snowflakes having two crystals of the same shape, one crystal is attached near the center of the other; where the two are of different shapes, a smaller crystal is attached near the tip of the other. (3) The nondimensional amplitude of the spiral falling motion of snowflakes composed of two crystals of different shape, is slightly larger than for those with crystals of the same shape. This suggests that snowflakes composed of different shapes are more likely to aggregate to other snowflakes or crystals. (4) In snowflakes consisting ?G three crystals, the centers are usually arranged in a straight line. (5) The nondimensional amplitude of the spiral motion of snowflakes consisting of three crystals increases with departures from the straight-line arrangement of their centers.
Surface Layer Salinity of Young Sea Ice
Authors: Ono Nobuo , Kasai Takashi
Published: September 2017

The high-salinity surface layer of young sea ice was subjected to field and laboratory experiments. Artificial pools, in which young ice was formed, were opened within a fast-ice sheet in the Saroma lagoon, Hokkaido, in February of 1983 and 1984. The salinity of 1 mm thick surface layer of the young ice was observed as high as 42.4‰, which exceeds the seawater salinity of 31‰. The surface salinity increased with rising surface temperature. When a load was placed on the fast ice near the pool, seeped brine of salinity 72.5‰ was observed on the surface of the young ice; and when the load was removed, the brine disappeared. Meanwhile, brine permeabilities, both upward and downward, were measured in the laboratory, Both permeabilities decreased logarithmically with lowering surface temperature. A remarkable anisotropy was observed: the upward permeability was greater than downward, and the ratio of upward to downward premeability increased with lowering surface temperature from 5 at -3 °C to 33 at -5°C. Upward and downward permeabilities in ms-1 were respectively 1x10-4 and 2x10-5 at -3°C, 2x10-5 and 6x10-7 at -5°C, and at -10°C upward permeability was 3x10-7.
Mechanism of Formation of Radially-Grown Meltpatterns on the Surface of Ice
Authors: Toukairin Akio
Published: September 2017

Patterns like brittle-stars, known as “radially-grown meltpatterns” are formed on the surface of ice from water gushing through a hole in thin snow-covered ice. This in turn melts the snow on the surface while extending outward along the water veins produced.

This study has successfully produced artificial meltpatterns and thus made possible the accurate clarification of the mechanics of formation. Incidentally, concentric circle meltpatterns were also found. Matters concerning artificial meltpattern simulation tests and the formation speed are also discussed in this paper.
Air and Water-Vapour Convection in Snow
Authors: Klever N.
Published: September 2017

Heat and mass transport by an air and water-vapour mixture (pore air) in snow due to thermal convection has been computed. It can be shown theoretically that thermal convection is always occuring in newly fallen snow, but never occurs in snow with rounded grains. Rayleigh numbers of depth hoar and partly settled snow are close to the critical Rayleigh number, therefore a small change in one or more of the snow parameters will decide whether there is convective or conductive heat transport.

The influence of thermal convection on the mass transport rates of water vapour in snow is computed based on the assumption of the ventilation approach. Although thermal convection occurs more often than previously assumed, its influence amounts only to about 2-3%.
Avalanche Flow Dynamics with Material Locking
Authors: Lang Theodore E. , Nakamura Tsutomu , Dent Jimmle D. , Martinelli Mario
Published: September 2017

Reported are results of incorporating recent snow avalanche processes into hydrodynamic uniform flow equations, used to model motion of snow avalanches. Actual modifications include the relating of dissipative coefficients of the flow model to slab release depth, the representation of the material as a locking fluid, and the mini-segmentation of the avalanche path at low flow speeds in order to numerically accomodate viscous transition and avalanche cessation of motion. The purpose in looking at different formulations of the uniform flow hydrodynamic flow equations is to reduce the variation in the drag coefficients when the theory is applied to different avalanche paths, as compared to what has been previous experience. The model that reduced parameter variation the most was one in which the total drag force decreased in an intermediate velocity range, a mechanism that has had recent experimental verification.
The Effect of Blowing Snow on Katabatic Winds in Antarctica
Authors: Kodama Yuji , Wendler Gerd , Gosink Joan
Published: September 2017

An acceleration of the katabatic winds during periods of blowing snow was observed in Adelie Land, Antarctica. Data collected by Automatic Weather Stations' (AWS) showed a change in the relationship between the katabatic term of the surface geostrophic wind (katabatic force) and the wind speed for periods of blowing snow. When measurements of the katabatic force were plotted against the cube of the wind speed, the slope was steeper for wind speeds at less than a threshold speed for blowing snow. The difference between these two slopes was partly explained by the effect of blowing snow entrained into the atmospheric boundary layer.
Grain Growth and Mechanical Behaviour of Polar Ice
Authors: Duval P.
Published: September 2017

Crystal size in polar ice caps increases with depth from the snow surface down to several hundred meters. Data on crystal growth in isothermal polar snow and ice show the same linear relationship between the size of crystals and their age. This paper reviews the mechanical behavior of polar ice which exhibits grain growth. Grain boundary migration associated with grain growth appears to be an efficient accomodation process for grain boundary sliding and dislocation glide. For grain growth to occur, strain energy must always be lower than the free energy of boundaries. The sintering of ice particles in polar firn is energized by the pressure due to the overburden of snow. Dislocation creep must be taken into account to explain the densification rate in the intermediate and final stage Constants of power law creep should depend on the crystal growth rate.
Ice–ocean dynamics and mechanics: a summary of the papers
Authors: Hutter Kolumban
Published: September 2017

A subjective review and summary of the key ideas presented at the conference is given, with occasional indications as to which scientific steps might resolve specific queries that arose from the work. The intention is to encourage closer reading of the papers.
Transient sub-surface uplift of a floating ice sheet
Authors: Dempsey J. P. , Zhao Z. G.
Published: September 2017

In this paper, the transient response of an ice sheet subjected to sudden uplift is investigated. The ice sheet is modeled as an infinite thin plate undergoing small deflections that is being pushed vertically upwards by a rigid flatended cylinder. The water underneath the ice sheet is modeled using incompressible potential flow theory. For a given motion of the cylinder, the current problem is reduced to a Volterra integral equation of the first kind for the indentation force. It is solved by transforming the governing equation into an integro-differential equation. For the physical quantities of interest, comparisons are made with related experiments.
Oceanographic and meteorological effects on autumn sea-ice distribution in the western Arctic
Authors: Muench Robin D. , Pease Carol H. , Salo Sigrid A.
Published: September 2017

Oceanographic, meteorological and sea-ice data were obtained from the northern Bering Sea and Chukchi Sea during the autumns of 1987 and 1988. Ice-edge location was observed from ships and via AVHRR satellite data, and ice-drift information was obtained from ARGOS-tracked drift buoys. Meteorological data were obtained from ships, from an ARGOS-tracked meteorological station and from synoptic charts. The ice edge was significantly farther south in 1988 than during other years and impacted the Alaskan coastline. In 1987, the ice edge was, conversely, anomalously far north. Ice melt-back in certain regions, such as along the Alaskan coast and in Herald Canyon, was due to input from warm ocean currents. The larger-scale interannual differences in ice extent were, however, due to interannual differences in the regional winds. In particular, the anomalous and extreme southward extent of the ice edge during 1988 was due to northerly to northwesterly winds, which held the summer pack ice against the the beach. Meltwater from this ice salt-stratified the upper water column, so that the ice eventually became effectively insulated against vertical flux of heat from the underlying warm water in the coastal current.
The physical basis for a dynamic Antarctic sea-ice model for use with an atmospheric GCM
Authors: Budd W.F. , Simmonds Ian , Wu Xingren
Published: September 2017

An observed ocean-drift data set is used as the basis of a wind-driven coupled ocean-sea-ice-atmosphere model including interaction and feedback. The observed characteristics of the Antarctic sea ice are described including the ice thickness, ice concentration and horizontal advection. The atmospheric model computes heat fiuxes, sea-ice growth, changes in concentration and advection. Sensitivity studies show reasonable and stable simulations of the observed sea-ice characteristics for the present mean Antarctic winter climate. The response times and feedbacks of the ice-atmosphere system as represented by the model appear to allow scope for the development of some persistence of anomalies.
The effect of confinement on the brittle compressive fracture of ice
Authors: Schulson E. M. , Jones D. E. , Kuehn G. A.
Published: September 2017

Granular, fresh-water ice was deformed at −40°C at 10−3 s−1 under confinement. Loading was applied such that confining stress, σ2 and σ3, were equal to each other and proportional to the highest stress, σ1; i.e. σ2 = σ3 = Rσ1. Two regimes were evident. At lower confinement, the fracture stress, σ1f, increases markedly as R increases. At higher confinement, σ1f increases less sharply. The transition occurs at about R = 0.15. Wing cracks were seen in the ice fractured within the low-R regime. The data are analyzed in terms of the frictional crack sliding-wing crack mechanism of brittle compressive fracture.
Microcrack nucleation in granular ice under uniaxial compression: effect of grain-size and tetmperature
Authors: Kalifa P. , Jones S. J. , Slade T. D.
Published: September 2017

Uniaxial compression tests were carried out on fresh-water, isotropic, granular ice at a strain rate of 6 × 10−4 s−1. We investigated the effect of temperature (between −2 and −39°C) and grain-size (1 mm–8 mm) on the critical stress and strain at the initial crack nucleation. The amount of non-elastic strain at this event was estimated. The critical stress for initial crack nucleation increased strongly with decreasing temperature, following an Arrhenius law. It also exhibited a linear increase with dg−1/2 (where dg is the average grain-size). It is shown that the results cannot be explained by the purely brittle model of Sunder and Wu (1990). The results are interpreted in terms of grain-boundary sliding, controlled by the intrinsic viscosity of the boundary.
Energy exchanges during indentation tests in fresh-water ice
Authors: Sodhi Devinder S.
Published: September 2017

The data from a small-scale experimental study on ice-structure interaction are used to compute the energy exchanges that take place during creep deformation and intermittent and continuous crushing of ice. The energy supplied by the carriage is partly stored in the structural spring, partly converted to kinetic energy, partly dissipated in deforming and extruding the ice and partly dissipated as heat in the damping mechanisms of the structure. Except for the heat dissipation, all other forms of energy were computed from the experimental data, and the heat dissipation was computed from the energy balance using the first law of thermodynamics. Plots of all forms of energy are shown in graphical form, in which their relative magnitudes, times of occurrence and interplay can be seen. The main result of this study is the thesis that intermittent crushing or ice-induced vibration takes place whenever there is an imbalance between the rates of work done by the carriage and the indentor and that there are no vibrations when these rates of work are equal.
Synoptic and seasonal variations of the ice-ocean circulation in the Arctic: a numerical study
Authors: Warn-Varnas Alex , Allard Richard , Piacsek Steve
Published: September 2017

The circulations of the Arctic ice cover and ocean are investigated using a coupled ice-ocean model. The coupling is strong and two-way for synoptic time scales, but is limited on seasonal time scales: the geostrophic ocean currents are not changed by the computed heat and salt fluxes. The ice-drift motion, Ekman transports and the wind-driven part of the barotropic circulation are examined for the months of February and August 1986, representing different atmospheric forcing, ice-thickness and ice-strength regimes. Initial examination of the results revealed no significant seasonal dependence of ice-drift response on the synoptic time scale, other than larger velocities with larger wind stresses. Daily maximum ice-drift velocities range from 20-40 cm s−1 in February, and 15-30 cm s−1 in August. The corresponding mean monthly maximum drifts were 11 and 9 cm, respectively. The drag associated with the geostrophic currents plays a much bigger role in the summer because of the lighter atmospheric stresses. The well-known reversal of the normally clockwise Beaufort Gyre to a cyclonic system in August takes place in a few days and lasts well into September. In February, the Beaufort Gyre varies between a large, clockwise system covering all the Canadian Basin to a small, tight gyre centered over the southern Beaufort Sea, without any hint of reversal or disappearance. Large areas of strong divergence were found in the Ekman transport patterns, as well as the ice-divergence fields, indicating areas where ice thinning, openings and new ice formation might occur. In August this occurred in the Chukchi Sea, and in February just north of Novaya Zemlya.
The propagation of characteristics in sea-ice deformation fields
Authors: Erlingsson Björn
Published: September 2017

The role of internal forces in determining the geometrical properties of local features such as leads and ridges in sea ice has been investigated. A description of the horizontal stress distribution in a granular material subject to two-dimensional deformations has been derived. The description yields expressions for the propagation of deformation characteristics in a granular deformation field with constant angle of internal friction. The characteristics are mathematical singularities interpreted as trajectories of constant state variables, e.g. ice concentration or ice thickness typified as leads, fractures, pressure and shear ridges. The derived descriptions are used to study the geometrical nature of curving and rectilinear lead patterns frequently observed in sea-ice deformation fields. An expression for the relationship between the arching (tangent angling) of characteristics and relative increase in shear (maximum shear stress) along them is derived. It is explained how the acute angle between large-scale rectilinear characteristics is related to the important mechanical property of the deformed material, the angle of internal friction. It is outlined how the derived results can be applied to study the horizontal distribution of internal forces in sea ice by using imagery data and stress measurements at one site only.
Sea-ice dynamics in the Weddell Sea in winter
Authors: Hoeber Heinrich
Published: September 2017

Observations of ice drift received from an array of ARGOS buoys drifting in the Weddell Sea in winter 1986 are described. Wind and current data are also available, permitting derivation of the complete momentum budget including the internal ice stress computed as residuum. It is shown that the variability of forcing both of the atmosphere and of the ocean is large, and that internal ice stress is not negligible; monthly vector averages amount to about half of the wind and water stresses. Coefficients of shear and bulk viscosity are derived according to Hibler's model of ice rheology; they turn out to be negative occasionally, in particular when small-scale forcing of the atmosphere is large.
Study of glacier meltwater resources in China
Authors: Zhenniang Yang , Xiaogang Hu
Published: September 2017

Glacier meltwaters are an important component of surface water resources in western China. Based on glacier inventories, the total glacier area in China is 5.87 x 104km2, the second largest for an Asian country. The total storage of water in glaciers is about 5132 x 103 km3, and the mean annual amount of glacier melt runoff is about 5.64 x 1010m3, o r 2% of the total surface water resources of China. From the late 1950s to the present, measurements have been undertaken of about twenty mountain glaciers, and data on hydrology and meteorology obtained. The relationship between heat balance and glacier ablation has been investigated but for glacierized areas where there are no data, ice-melt runoff can be estimated from climatic data. Runoff of glacier meltwater decreases with increasing aridity of the climate. The impact of glacier meltwater on the regimes of mountain streams in different environments are described in this paper.
The terminus of Hubbard Glacier, Alaska
Authors: Krimmel Robert M. , Trabant D. C.
Published: September 2017

Hubbard Glacier advanced across the entrance of Russell Fiord in May 1986, transforming the fiord into a lake, which began filling with fresh water. The dam failed in October 1986. The calving terminus of Hubbard Glacier has been mapped with increasing frequency for nearly a century. A mapping interval of a few years establishes that the terminus has made a slow, but accelerating, advance. Recently the terminus has been mapped several times per month using vertical photography, ground surveys, and time-lapse cameras. At this frequency of observation, the terminus position is found to fluctuate seasonally. These seasonal fluctuations are compared with those of Columbia Glacier, where a longer detailed record is available. Although Columbia Glacier is now undergoing a drastic retreat, it continues to have seasonal length changes similar to those it experienced before the retreat began. The lengths of both Columbia and Hubbard Glaciers are extended in the spring, and retracted in the fall. The relatively long period of record for Columbia Glacier shows consistent seasonal variation in length and, when compared with the short period of record for Hubbard Glacier, suggests that there are consistent seasonal differences in length at Hubbard also. The lower Hubbard Glacier diverges, feeding ice into Disenchantment Bay and Russell Fiord, and advances and retreats synchronously over most of its width. The tidal current, which passes through the 250–500 m wide entrance to Russell Fiord, does not affect the seasonal advance and retreat in that area significantly.
Recent fluctuations of glaciers in the Gongga mountains
Authors: Zhen Su , Shiyin Liu , Ninglian Wang , Aiping Shi
Published: September 2017

From field observations and historical information, it is found that there are generally three end moraines in front of glaciers in the Gongga mountains. These moraines were formed during the Little Ice Age and represent three glacier advances. During the last 100 years, the glaciers have been in continuous retreat except for two periods of stability or even slight advance, one in the beginning of the 20th century, up to the 1920s, and the other from the middle 1960s to the early 1980s. The amplitudes of glacier fluctuations were greater on the east slope than on the west.
Characteristics of the distribution of glaciers in China
Authors: Zongtai Wang , Yang Huian
Published: September 2017

About 80% of the glaciers in China have been inventoried. Based on the inventory and an estimate of the area that has not been inventoried, there are about 45 375 glaciers in China, with a total area of 58 735 km2 and an ice volume of about 5.31 × 1012 m3. These glaciers are widespread in high mountains and in highland areas in western China, between 27°06′ to 49°09′N and 71°32′ to 103°54′E. The glacierized area in China comprises about 16% of the alpine glacier area in the world, and 47% of that in Asia. There are about 230 large glaciers, with areas exceeding 100 km2, in the world outside Antarctica and Greenland. Among them, 65 (28%) are in Asia and 31 (13%) in China.
Can the mass balance of the entire glacier area of the Tien Shan be estimated?
Authors: Dyurgerov M.B. , Kunakhovitch M.G. , Mikhalenko V.N. , Sokalskaya A. M. , Kuzmichenok V. A.
Published: September 2017

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

In computation procedure, the vertical profile of snow accumulation in these regions and exponential dependence of variation of ablation with altitude are used. Thus the mass balance in each basin, bn, was calculated on the basis of these curves and represented in its relation with the equilibrium line altitude (ELA). It is shown that the relation ELA = f(bn) is linear when the range of bn values is close to zero, and in all altitude intervals this relation can be described by hypsographic curves, in all basins bn positive up to an ELA elevation of 3450 to 3500 m a.s.l. For average annual altitude of ELA, bn is negative for all regions. So the glaciers of these mountains add about 4 km3 of water to the total annual runoff.
Temperature regime studies and mathematical calculations for dry snow covers in the western Tien Shan mountains, China
Authors: Hong Ma , Zongchao Liu , Zhian Yang
Published: September 2017

A mathematical model is proposed to simulate the spatial and temporal variations in snow temperature. The model is based on the non-steady, one-dimensional, heat-conduction equation with internal heat source. It gives the change in time of the internal temperature field of the snow as it responds to varying surface temperature and periodic solar radiation. Verification of the model is accomplished by comparing the calculated results with observed data. The model may serve as a basis for quantitative investigations of snow temperature and temperature gradient, and relevent problems such as energy-mass transfer processes. Moreover, it allows better understanding of the relationship between external atmospheric conditions and the internal thermal regime of dry snow covers in the western Tien Shan mountains.
Influence of local factors on the distribution of snow resources in northern Tien Shan
Authors: Severskiy S.I. , Severskiy I.V.
Published: September 2017

Methods of quantitative evaluation of the influence of local factors such as slope exposure (aspect and gradient) and types of vegetation on the distribution of snow cover found in the northern Tien Shan are described. This investigation is based on regular measurements of snow depth and density at different altitudes and exposures, and with different vegetation types. A strong statistical relationship was obtained between snow cover on the one hand and slope exposure and vegetation types on the other. Local factors have a stronger influence on the distribution of snow cover than elevation. These methods were used for the estimation of the distribution of snow cover in a typical river basin. The results obtained differ significantly from the results of evaluations made by traditional methods.
An experimental study of the water and heat balance in the source area of the Ürümqi River in the Tien Shan mountains
Authors: Ersi Kang , Daqing Yang , Yinsheng Zhang , Xinyuan Yang , Yafeng Shi
Published: September 2017

In the source area of the Ürümqi River, during the glacier ablation season, net radiation is the only heat input to the tundra, averaging 119W m−2 in July and August, more than twice that to the glacier, where additional heat input is contributed by sensible heat. The heat input to the tundra is mostly lost by evaporation, which accounts for 86%, while the input to the glacier is mostly lost by melting. The relatively small heat input to the glacier and the large evaporation rate of its surroundings favour the glacier’s existence. Most precipitation occurs between June and August, accounting for 66% of the annual total. Precipitation increases with altitude in average conditions during the ablation season; the annual precipitation is estimated to be about 650 mm at the mean equilibrium line altitude of 4030 m. This amount is considerably larger than that of the surrounding area. Evaporation is estimated at 270 mm a−1 on the tundra, reducing the runofTin a rather large proportion, and 120 mm a−1 on the glacier. Almost all runoff takes place between May and September, and is mostly concentrated in July and August when the glacier melt is the most intense. When air temperature is high during the ablation period, although the precipitation is less, runoff could peak because of the glacier melt. Based on the measured runoff and estimated regional precipitation and evaporation, the glacier mass balance is calculated and discussed.
An outline of avalanches in the Tien Shan mountains
Authors: Ruji Hu , Hong Ma , Guo Wang
Published: September 2017

The seasonal snow cover in the Tien Shan mountains is characterized by low density, low liquid-water content and low temperature. It is known as typical dry snow. Large temperature gradients in the basal layer of the snow cover exist throughout the entire period of snow accumulation, and depth hoar is therefore extremely well-developed. Full-depth depth-hoar avalanches, however, seldom occur. Avalanches in the Tien Shan mountains are mostly loose snow avalanches. Although normally not large in size, they are the most dangerous type. The occurrence of hazardous avalanches shows cycles of about ten years because of periodic climatic variations.
Energy balance of a snow cover and simulation of snowmelt in the western Tien Shan mountains, China
Authors: Hong Ma , Zongchao Liu , Yifeng Liu
Published: September 2017

The energy-balance approach was used to calculate snowmelt at a site in the mid-mountain zone of the western Tien Shan mountains. During a 19-day snowmelt period, the results showed that net radiation and sensible heat fluxes accounted for 76.9 and 23.1% of the incoming energy, while snowmelt and evaporation consumed 97.1 and 2.9% of the energy, respectively. Snowmelt calculated from the energy balance compares favourably with measured values, indicating the suitability of the energy-balance approach for estimating the rate of snowmelt in the mountain environment of the western Tien Shan.
Glacial and lake fluctuations in the area of the west Kunlun mountains during the last 45 000 years
Authors: Chaohai Liu , Shijie Li , Yafeng Shi
Published: September 2017

There appear to have been several important glacial advances on the southern slope of the west Kunlun mountains, Tibetan Plateau, since 45 000 a BP. Based on the record of alternating till and lacustrine sediments and 14C determinations, these advances are dated to 23 000–16 000, 8500–8000, and 4000–2500 a BP, and to the 16th–19th century AD, with regional variations occurring during each of the advances. The glaciation of 23 000–16 000 a BP is equivalent to the last glacial maximum (LGM) and its scope and scale were much larger than any of the others.

Lake changes are a response to both tectonic uplift of the plateau and global climatic change. With regard to the latter, both changes in precipitation and changes in the extent of glaciation can affect lake levels. High lake levels occurred during interstadial conditions between 40 000 and 30 000 a BP, when the area experienced a relatively warm and humid climate, and during the LGM, between 21 000 and 15 000 a BP. During the Holocene, lakes have been shrinking gradually, coincident with the dry climate of this period of time.
Jökulhlaups in the Kunmalike River, southern Tien Shan mountains, China
Authors: Jinshi Liu
Published: September 2017

Hydrological records of Kunmalike River in the southern Tien Shan show that jökulhlaups have occurred about once a year since 1956 from the glacier-dammed Lake Mertsbacher. The maximum peak discharge of the jökulhlaups is 1920 m3 s−1 and the maximum total volume is 3.275 × 108 m3. The release mechanism of the glacier-dammed lake is not a mechanical failure of the glacier dam, but drainage of pressurized water through a subglacial tunnel which is enlarged due to melting by frictional heat in the flowing water and advective heat from the lake. There is no relationship between the size of the jökulhlaups and the mean summer air temperature. The seasonal flood peaks in Kunmalike River have become larger and the flood periods have been prolonged both in spring and winter because of the draining of the lake. Once a jökulhlaup has started, its discharge is forecast hour by hour by extrapolating the measured hydrograph as exponential curves.
Ice charting based on multispectral satellite data in the Baltic Sea
Authors: Golovko V.A. , Leppäranta M. , Kalliosaari S. , Sedunov YU.S. , Volkov A.M.
Published: September 2017

Results are presented from an experiment concerning operational space-borne ice charting based on the Russian Ocean and Resource satellite systems. The surface truth consisted of routine operational data, helicopter-borne reconnaissance, and some ground measurements. Examples of the satellite imagery are given and identification of ice types is described. Cluster-analysis has been used for automatic image segmentation. The potential of these satellites in operational ice charting is discussed. A 160 m resolution optical scanner and a 2 km resolution radar are found to be very useful complements to the present routine system.
Melting characteristics of ice blocks immersed in quiescent saline water
Authors: Fukusako Shoichiro , Yamada Masahiko , Watanabe Chikara
Published: September 2017

An experimental and analytical study has been carried out to investigate the melting characteristics of ice blocks immersed in quiescent saline water. A horizontal ice cylinder and both downward- and upward-facing inclined ice plates were used as the testing blocks. The experiments were carried out in 3.5% (by weight) saline water at ambient temperatures ranging from 1.8° to 25.0°C for all kinds of ice blocks. Ice plates were tested at inclination angles from 0° to 75°. For downward-facing ice plates, melting rates were determined analytically using the profile method.
The elastic modulus of columnar-grain fresh-water ice
Authors: Gold Lorne W.
Published: September 2017

An analysis is presented of stress and strain measurements made during an investigation of the characteristics of cracks formed in columnar-grain, type S2 fresh-water ice, during uniaxial, compressive loading at the nominal strain rates of 10−3, 10−4 and 10−5s−1, and temperatures of −5°, −10°, −20° and −30°C. The analysis shows that for this range of strain rate and temperature, ice behaves as an anelastic solid. Results are given for the time, grain-size and temperature dependence of the elastic modulus in the plane perpendicular to the long direction of the grains. They are shown to be in reasonable agreement with results of an earlier study of the anelastic behaviour of the same type of ice. It is suggested that the grain-size and temperature dependence of the elastic moduli of ice for this range of strain rate and temperature may be due, in part, to the dependence of the relaxation time on these variables.
Microcracking and shear fracture in ice
Authors: Rist M.A. , Jones S.J. , Slade T.D.
Published: September 2017

The relationship between microcracking and ice Strength has been examined using triaxial apparatus in which track damage can be inhibited by the imposition of confining pressure. Shear fracture in ice is observed to be a rapid, unstable process with no apparent indication of tensile crack localisation or interaction prior to failure and no accompanying large-scale volumetric changes, at least to within 1 ms of the occurrence of macroscopic failure. Shear fracture strength displays little or no dependence on confinement at moderate pressures (P = 5–20MPa), and there is no evidence of significant crack sliding before macroscopic fracture under these conditions. Where flow with distributed microcracking occurs, yield strength can also remain remarkably unaffected by confining pressure, despite reduced crack damage. Particularly under conditions where microcracks are induced by predominantly elastic strains, they may remain stable and non-interacting even at high volumetric densities.
An analytical model of icicle growth
Authors: Szilder Krzysztof , Lozowski Edward P.
Published: September 2017

A model of icicle growth has been developed based on an analytical solution of the differential forms of the conservation of energy and mass. The problem has been formulated using dimensionless variables defined as the ratios of the various heat fluxes which determine the icicle’s growth. The evolution of the dimensionless icicle shape has been expressed as a function of the variation of the convective heat transfer with icicle radius. The time interval needed for the icicle to reach its maximum length and the variation of the icicle mass and drip rate are expressed in dimensionless form.
An error analysis of the techniques used in the measurement of high-speed friction on snow
Authors: Colbeck S. C.
Published: September 2017

Controlled tests are needed to find the coefficient of friction of snow as a function of speed. An error analysis shows how the test must be designed to give accurate answers. It seems necessary to use a remotely controlled, aerodynamical sled in place of a skier to get accurate results. Otherwise, two sets of tests are necessary, one to determine air drag versus speed and one to determine the frictional force versus speed, and even these tests would probably not give satisfactory results. The slope used for testing should be sleep for a quick acceleration and then uniform, but not flat, where the actual measurements are taken. A continuously reading speed sensor is needed, not discrete measuring points. Even with the underlying principles understood, there will still be many practical problems to be solved before accurate results can be obtained.
Two-dimensional analysis of ice ridging in the Beaufort Sea using aerial photography
Authors: Lewis J. E. , Budkewitsch P. , Newton G. , Sayed M. , Frederking R. M. W.
Published: September 2017

Aerial photography was obtained for the Beaufort Sea north of Tuktoyaktuk. The flight path covered two distinct ice zones over a 15.5 km transect extending perpendicular to the coast, yielding fifty-nine photographs at a scale of 1 : 2000. The process of ridge extraction was automated using a series of computer algorithms for image filtering, edge detection and edge linking. Examples from two different sections along the transect are chosen for presentation: (a) a heavily ridged area, and (b) an area with one dominant linear ridge feature that separates ice cover of different age. Two parameters used in the automated process, a minimum edge gradient and minimum number of connected pixels said to form a continuous ridge segment, influence the number, length and spatial pattern of extracted ridges. Direct one-to-one correlations between manually interpreted ridges from photographs and the algorithm extracted ridges from digital data are not always possible. However, results indicate that the automated ridge extraction procedure reliably characterizes the overall direction and density of the ice ridges. The distribution of the ice-ridge directions is estimated from circular (angular) histograms constructed directly from the digital data. Analysis of the Beaufort Sea transect reveals that the ice ridging is strongly anisotropic, with a principal direction parallel to the local coastline.