Snow crystals scavenge aerosols in the atmosphere during the processes of growth and precipitation. Several kinds of flyash are found in acid snow by scanning electron microscope examination. Flyash particles from coal fired electric power plants in Fairbanks, Alaska, were found to be spherical or irregular in shape with a 0.2 to 50μm diameter, and were rich in calcium, silicon, aluminum and iron. The pH of 35 snow samples in Fairbanks ranged from 5.60 to 7.48. The acid snow was changed to alkaline snow by dry fallout of calcium-rich flyash from the electric power plants, which were using calcium-rich Alaskan coal.

Flyash particles from three oil fired heating plants in Hanover, New Hampshire, were spherical and 10 to 80 μm in diameter, with gas escape holes, and were always sulfur rich. The pH values of fresh snow from 44 snowfalls were measured to range from pH 3.96 to 5.45 in Hanover. The mean hydrogen ion concentration was calculated to be 10-448 mol/L for 22 snowfalls in 1980-84, and 10-4 mol/L for 22 snowfalls in 1972-73.

Computer analysis is carried out to predict the force that bears upon a horizontal beam embedded in settling snowpack. Use is made of extensive experimental data on snow depth, layering and density, and on measured force on a test beam, in order to evaluate the internal structural arrangement in a finite element representation of the region in the vicinity of the beam. The compressive secondary-creep viscoelastic properties and the densification properties of the snow are accounted for in the computer modelling. Results show that the bearing force on the beam develop from direct snow weight, from shear transfer by adjacent snowpack, from basal weakening below and to the side of the beam, and from snow densification above and to the side of the beam producing a bridging mechanism. These findings corroborate with related experimental results and point out the need for further refinement in definition, particularly of the bridging mechanism, which produces large force incrementation on the beam compared to the other mechanisms noted.

Values Of Effective thermal conductivities of snow and firn were obtained at Filchner Ice Shelf (Antarctica). We employed a transient line source method (a needle probe with a diameter of 1.6 mm) for conductivity determination, which allows quick measurements with high spatial resolution. Our data yield a linear relationship between effective thermal conductivity (lg keff) and density (p) of snow which implies a strong dependence of thermal conductivity on density for 0.24≤p≤0.42, Comparison of thermal conductivities and other snow pit data suggests that density alone is a poor measure of effective thermal conductivities of snow and firn. We propose that grain structure is probably the governing parameter in determining heat transport in the upper firn layers.

Relations between structures and physical properties of snow of four 30-m cores in Mizuho Plateau, Antarctica were investigated by measuring their specific areas of internal free surfaces and air permeabilities. The specific area of internal free surfaces and the air permeability decreased with increasing depth. Both of the depth profiles showed a kink at a depth of a critical density 550 kg/m3, indicating a change in the physical mechanism of densification. The drastic decrease of the specific areas above the depth of the kink was considered to be mainly caused by rounding and growth of ice particles; the gradual decreases below the kink were attributed to the development of bonding and particles.

Measured air permeability was compared with the theoretical one for randomly packed powders of uniformly sized solid particles. The discrepancy between the measured and theoretical permeabilities was explained by the change in shapes and sizes of air channels in the snow. The depth hoar formation, which was active in regions with smaller accumulation of snow, was considered to result in the favorable shapes of channels for air permeation.

If cold firn has reached a density of about 0.55 Mg m-3, further densificaron occurs by a sintering process which increases the contact surface between the firn grains. The pore volume is decreasing continuously but the firn remains permeable to air up to a density of 0.82 Mg m-3. At about this density the remaining air in the pore volume is closed off in isolated bubbles. We are interested in the age and the age distribution of the air enclosed in bubbles relative to the age of the surrounding ice, and are investigating the development of the pore volume in firn.

A newly constructed measuring device allows the field measurement of the amount of air which is already enclosed in bubbles of firn samples. Measurements have been made during summer 1983 in Greenland and during winter 1983/84 at the South Pole. The results are discussed and compared with results obtained with a simplified statistical sintering model, using some results of percolation theory.

Estimates of internal accumulation for five Alaskan glaciers in different climates suggests that internal accumulation occurs in glaciers throughout Alaska. A method of estimating the quantity of internal accumulation is based on the annual minimum temperature ?Γ the snow-firn interface. The consistency of the estimates suggests that valid approximations of internal accumulation can be made over large areas. The estimates have not been confirmed by measurements of mass change, but are believed to be accurate within 10 percent. Point balance quantities of internal accumulation range from 0.65 m a-1, which is 64% of the annual accumulation on McCall Glacier, to 0.12 m a-1, 7% of the annual accumulation on Wolverine Glacier. The amount of internal accumulation decreases rapidly from north to south in Alaska; however it should be expected worldwide where sub-freezing, porous firn is invaded by water.

Internal accumulation occurs in temperate glaciers in strongly maritime climates as well as glaciers in cold continental climates where it delays the onset of runoff, accelerates the process of converting snow into glacier ice, and explains the occurrence of temperate glaciers in permafrost areas.

A device capable of measuring the extinction coefficient of solar radiation within the snow cover was developed, using small silicone photocells as sensors. Extinction coefficient measured for natural snow covers in the field was 37-97 m-1 for dry snow of density 90-470 kg m-3. It decreased in the process of metamorphism from new snow to slightly compacted snow, and increased in the process of settlement from slightly compacted to compacted snow. It was 23-58 m-1 for wet snow of density 430-530 kg m-3 and in water content from 5-15%, being smaller than that for dry snow of the same density. The authors also determined local temperature increase of snow cover related to absorption of solar radiation. The temperature profile within the snow cover was calculated by solving the equation of heat conduction including the term of absorption of radiative energy. Measured and calculated snow temperatures agreed well, indicating the accuracy of the extinction measurements.

A large scale study on the dependence of time lag of runoff on snow depth and stratigraphy was carried out in a watershed. The time lag in peak runoff was found to be increased by 1.5 - 4 h per I m increment in snow depth. Although the data were widely scattered, it was found that the time lag series converged in a line every year and that discrete layers in the snow cover composed in a warm winter, accelerated meltwater flow.

Subtracting the time of propagation through a snowcover from the total time lag, the effect of size of a watershed on a delay in runoff was rearranged, as follows: where Tf is the time lag in min after discharge from a snow cover, A the area of a watershed in km2, Re the effective snowmelt in mm/hr. The time lag Tf increases only by 1.5 times when an area of a watershed is increased by a factor of ten.

In order to clarify the metamorphic process of snow particles immersed in water, distributions of grain size were examined as functions of time (0.1 to 1 000 hrs) and impurity concentrations. When disaggregated snow particles were immersed in water kept at 0°C, each particle became spherical and grain coarsening took place with time. The average diameter increased with cube root of time and the average volume increased in proportion to time. Grain coarsening was not detected in a kerosene environment.

In solutions of glucose, NaCl, HC1 and dextran, the growth rate was controlled by the concentration and the diffusivity of the solute. The higher concentration and the lower diffusivity, the grain coarsening was controlled. The grain coarsening is explained by the disappearance of relatively small particles and growth of relatively large ones, caused by differences of the equilibrium temperature of each particle if the total ice mass is conserved.

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.

At temperatures slightly below 0°C, ice filling a smooth-walled chamber that has porous phase barriers at either end can move through the chamber in a process resembling regelation; supercooled water passes through one barrier and freezes at the same time that ice melts at the other, emerging through the second barrier as supercooled water. The process may be induced mechanically (by differential water pressures at the phase barriers) or thermally {by imposed temperature differentials). The ice moves as a rigid body with slippage at the ice-wall boundary of the chamber. An apparent coefficient of static friction can be deduced and appeared to be about 0.12 for ice at a machined nylon wall at about -0.04 ˚C.

Extensive internal melting (puddle formation) was observed on the sheet of fast sea ice near Ongle Island, East Antarctica in 1980. In late November that year, when surface melting was not seen, puddles did not form beneath snow cover with a hig albedo (0.7 to 0.8) but were present in bare sea ice with low albedo (0.2 to 0.3). Electro-conductivities of puddle water ranged from 3.3-6.6 mS/cm; these were higher than for drinking water from an iceberg or snow drift (below 0.9 mS/cm), but lower than for sea water (30-42 mS/cm). Puddle water is therefore considered to originate from the internal melting of sea ice, as a result of the internal absorption of solar radiation from the surface down to a certain depth. The mechanism of puddle formation is explained by numerical analysis of a differential equation of heat conduction, which includes the amount of heat evolved by the absorbed solar radiation.

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.

The purpose of this work is to study the relationship of energetic and physical properties of polymetric materials with ice adhesion, and to develop the material to prevent ice adhesion. From various parameters of water and ice, dispersion and hydrogen bond contribution of surface free energy of ice were calculated. Using these values and that of contact angle formed between Ice and polymer in the air and also in paraffin, work of adhesion W-πe and W were determined respectively. The difference W-(W-πe) has made it possible to evaluate the effect of surface pressure n on ice adhesion. On the other hand, actual adhesive strength of ice was measured. Some correlations between theoretical and observed values were found. Further, visco-elastic properties of polymers below icing temperature and temperature dependence of strain in the ice/polymer system were investigated. The results showed some characteristics of polymers which are related to molecular mobility at lower temperature, are effective in reducing the adhesive strength to ice.

Numerous attempts were made to develop coating materials to prevent ice adhesion. A composite polymer composition, which has peculiar ingredients and structure, was proposed and found to provide the ability for the lowest ice adhesion. Ice preventive mechanism of the film was discussed.

Snow stratigraphical studies, together with crystallographic and oxygen isotope analyses, have affirmed the existence of a complete range of ice formation zones on the Law Dome, Antarctica. Asymmetric distribution of these zones and changes in the types of ice formation with depth in snow pits dug near the boundaries of the zones show an asymmetry in accumulation and thermal conditions in different sites on Law Dome, and a climatic change in past years. Crystallographic studies of ice from two boreholes near Cape Forger (BHC i and BHC 2) show change of microtexture and fabric of the ice crystals with depth. Six different layers of ice can be identified: 1) a deposition layer with polygonal shaped crystals, an ice fabric which is dependent on the ice formation process; 2) a transition layer with porphyrblastic crystals and a girdle fabric pattern developing toward a two-pole fabric; 3) a fine grained layer with cataclastic crystals and strong, nearly vertical single pole c-axis fabric; 4) a coarse grained layer with large, interlocking, branched crystals and a diamond pattern of fabric; 5) a second fine grained layer with single maximum fabric; 6) a second coarse grained layer with multi-maxima fabric. The origin of the second fine grained layer, found in the ice of the last glaciation is discussed. The author suggests that this ice results from conditions during the last glaciation.

Heat balance studies were carried out during summer ablation periods 1960-1983 by the glacial investigation team of the Chinese Academy of Sciences. The effect of energy exchange on development of mountain glaciers was determined, based on the observation of heat exchange over the glacial surface of various mountainous regions. Relationships between energy transfer and climatic parameters under different climatic regimes and landform conditions are analyzed in detail. It was found that the most important heat source for snow-ice melting is radiation, a contribution amounting to between 59.0% and 92.1% of the total. Sensible heat contributed 8 - 36%. The sensible heat flux depends on the bulk transfer coefficient and the glacier cooling effect. The mean value is about 16.3 Ly/day.K.. With the decrease of sea influence, altitude of the snow-line is elevated, aridity of glacier climate increases, evaporation increases gradually and melting decreases, providing conditions for glacial nourishment. When the glacier is covered with a debris layer, the glacier heat balance in continental regions is altered. Finally, the authors’ investigation on the glacier No 1, at the headwater of Urumqi river, shows that differences in structure of glacier heat balance are mainly the result of the influence of the topography and albedo on net radiation. Finally, diagrams of distribution of net radiation in space and time are presented.

In this paper, some features of energy balance terms will be discussed in respect to the melting capacity available at the surface of Vernagtferner in the Oetztal Alps. The climatic pattern of summer 1982 is described, then the method of calculating individual terms (shortwave and longwave radiation balance, sensible and latent heat flux) from records of radiation, air temperature, humidity and wind. The results of these calculations are discussed for ice, firn and snow areas of the glacier. In particular the relationship between the four terms is shown for 15 July 1982, the day with highest meltwater production in 1982. These values are then compared with the maximum values of the individual terms, showing that the highest meltwater production is caused by the combination of quite high values of the individual terms, but not of the absolutely highest ones. The importance of sensible heat flux for meltwater production in 1982 is discussed: comparison between meltwater production for the whole summer and measured runoff shows reasonable accordance.

Data on temperature and accumulation of high altitude firn in the Alps are compiled and discussed. Firn temperature varies with incoming radiation (slope aspect) at a given altitude. The altitudinal gradient of temperature in highly permeable firn bodies appears to be about twice as high as the mean lapse rate of air temperature. “Cold infiltration” takes place above about 3500 m a.s.l. Firn temperatures on the highest peaks are around -15°C. Accumulation (net balance) also decreases with increasing altitude from about 3m H2O at 3500 m a.s.1. to around 0.5 m H2O at wind exposed sites between 4300 and 4800 m a.s.l. Probably this is strongly due to wind erosion and topographical effects. However, temperature and accumulation not only appear to be interrelated, but also seem to be positively correlated to the heat applied to the surface. Assuming the observed altitudinal gradients have remained constant in time, it can be estimated that high altitude firn bodies have become considerably warmer since the last century. CO2-induced atmospheric warming could lead to a drastic change in (he mass turnover and flow activity of high glaciers, in wind-exposed places where wind erosion of the snowpack becomes a controlling factor of accumulation.

The reflectance distribution of polar and alpine snow was measured under various conditions at 450, 514, 750 and 1000 nm wavelength. A reflectance peak appears in the azimuth directions up to 60° to both sides of the solar azimuth, is more prominent at high zenith angles of incidence and of reflectance and is better developed in coarse than in fine-grained snow. Under natural conditions, when only hemispherical-directional reflectivity can be determined, the anisotropy is spread in the blue part of the spectrum where the diffuse component dominates global irradiance. Bidirectional reflectance of a laser beam at 514 nm over alpine snow is comparable to that at 1000 nm over polar snow.