All available mean annual accumulation data on the Greenland ice sheet (excluding the Thule peninsula) have been collected and analyzed using multiple regression techniques to develop equations capable of predicting mean annual accumulation. The analysis was carried out for north Greenland, south Greenland, and for the transition zone between the two major regions. The resulting equations show that mean annual accumulation can be predicted from the independent parameters latitude, longitude and elevation. The patterns of accumulation are shown in a series of isohyetal (contours of accumulation in terms of water) maps. The major feature shown is a well defined asymmetry in accumulation; a pronounced east-slope maximum in south Greenland and an equally pronounced west-slope maximum in north Greenland. Poleward of lat. 69° N., isohyets decrease in elevation to the north. Mean annual accumulation ranges from >90 g./cm.2 in south-east Greenland to <15 g./cm.2 in north-east Greenland. A brief discussion of mass balance estimates of the Greenland ice sheet and of the relevance of this study to them is included.

In the summer of 1972, the amount of ice melt obtained by stake measurements on the McCall Glacier, Brooks Range, was compared with the discharge of a small controlled run-off site, and with heat balance calculations. For daily values the agreement was not always good; however, for the 11 d period for which the study was carried out, the agreement can be considered as excellent. The amount of ice melt calculated from run-off and heat balance gave 3.5 and 1.2% higher values, respectively, than the direct measurements. This is encouraging, insofar as it suggests that it may be possible to calculate the combined ice, water, and heat balance for the glacier as a whole.

A study of the movement of Rusty Glacier was undertaken and continued through four summers because it is believed to be a surging glacier in the last stages of the inactive phase preceding a surge. The entire glacier is very slow moving, essentially motionless in the lower third and most rapid in an area well above the firn line. Unusually steep flow-line emergence angles and higher than average longitudinal compression rates in the lower–middle part of the glacier indicate gradual thickening of the ice above the stagnant lower tongue. There is no clear correlation between local variations in flow rates and surface or bottom topography. The glacier is mostly colder than 0° C to the bottom, and in the one known area of 0° C bottom temperature, flow rates are not greater than elsewhere. Although the glacier is everywhere very thin, maximum flow rates seem clearly related only to variations in ice thickness. The nearby Trapridge Glacier is also a surging glacier and exhibits a strikingly similar flow pattern.

Glacial ripping involves glaciotectonic disintegration of rock hills and extensive removal of rock at the ice-sheet bed, triggered by hydraulic jacking caused by fluctuating water pressures. Evidence from eastern Sweden shows that glacial ripping caused significant subglacial erosion during the final deglaciation of the Fennoscandian ice sheet, distinct from abrasion and plucking (quarrying). Here we analyse the ice drag forces exerted onto rock obstacles at the base of an ice sheet, and the resisting forces of such rock obstacles: glaciotectonic disintegration requires that ice drag forces exceed the resisting forces of the rock obstacle. We consider rock obstacles of different sizes, shapes and fracture patterns, informed by natural examples from eastern Sweden. Our analysis shows that limited overpressure events, unfavourable fracture patterns, low-transmissivity fractures, slow ice and streamlined rock hamper rock hill disintegration. Conversely, under fast ice flow and fluctuating water pressures, disintegration is possible if the rock hill contains subhorizontal, transmissive fractures. Rock steps on previously smooth, abraded surfaces, caused by hydraulic jacking, also enhance drag forces and can cause disintegration of a rock hill. Glacial ripping is a physically plausible erosion mechanism, under realistic glaciological conditions prevalent near ice margins.

The “T term” in the longitudinal stress-equilibrium equation for glacier mechanics, a double y-integral of ∂2τxy/∂x2 where x is a longitudinal coordinate and y is roughly normal to the ice surface, can be evaluated within the framework of longitudinal flow-coupling theory by linking the local shear stress τxy at any depth to the local shear stress τB at the base, which is determined by the theory. This approach leads to a modified longitudinal flow-coupling equation, in which the modifications deriving from the T term are as follows: 1. The longitudinal coupling length is increased by about 5%. 2. The asymmetry parameter σ is altered by a variable but small amount depending on longitudinal gradients in ice thickness h and surface slope α. 3. There is a significant direct modification of the influence of local h and α on flow, which represents a distinct “driving force” in glacier mechanics, whose origin is in pressure gradients linked to stress gradients of the type ∂τxy/∂x. For longitudinal variations in h, the “T force” varies as d2h/dx2 and results in an in-phase enhancement of the flow response to the variations in h, describable (for sinusoidal variations) by a wavelength-dependent enhancement factor. For longitudinal variations in α, the “force” varies as dα/dx and gives a phase-shifted flow response. Although the “T force” is not negligible, its actual effect on τB and on ice flow proves to be small, because it is attenuated by longitudinal stress coupling. The greatest effect is at shortest wavelengths (λ 2.5h), where the flow response to variations in h does not tend to zero as it would otherwise do because of longitudinal coupling, but instead, because of the effect of the “T force”, tends to a response about 4% of what would occur in the absence of longitudinal coupling. If an effect of this small size can be considered negligible, then the influence of the T term can be disregarded. It is then unnecessary to distinguish in glacier mechanics between two length scales for longitudinal averaging of τb, one over which the T term is negligible and one over which it is not.

Longitudinal flow-coupling theory also provides a basis for evaluating the additional datum-state effects of the T term on the flow perturbations Δu that result from perturbations Δh and Δα from a datum state with longitudinal stress gradients. Although there are many small effects at the ~1% level, none of them seems to stand out significantly, and at the 10% level all can be neglected.

The foregoing conclusions apply for long wavelengths λh. For short wavelengths (λ h), effects of the T term become important in longitudinal coupling, as will be shown in a later paper in this series.

This paper describes how to grow single crystals of ice of desired orientation by applying the method of seed extraction from the melt. A single crystal of more than 1 g can be grown in less than one hour.

Glaciological studies during the Sheffield University Expeditions to Kilimanjaro in 1953 and 1957 included a survey of the glaciers and a close examination of the Penck Glacier and the stagnant remnants of the ice cap on the summit. The Penck Glacier has done little downcutting although it rests on friable rock. The glaciers and summit remnants are rapidly retreating, the Penck Glacier having retreated 3 m. in 3 months in 1957, and nearly 300 m. since 1912. The main accumulation zone appears to be at about 4,500–5,000 m. with a local “low level” firn line and an upper firn line above the top of the mountain. Maps of the glaciers, their recent fluctuations and moraines are being prepared. The glaciological and meteorological observations in 1957 form part of the I.G.Y. programme for East Africa.

During the summer of 1983 a 2 kW array of solar voltaic panels was used to power a drill which collected two cores of 154 m and 163 m length to bedrock on the Quelccaya ice cap in Peru. The operation and performance of this array are discussed, considering the need for future requirements in remote pristine areas of the world.

Since its inception in 1975, the Northwest Avalanche Center (NWAC) has developed and produced micro- and mesoscale weather forecasts to support avalanche forecast and control needs for the Olympic and Cascades Mountains of Washington and Oregon, U.S.A. This paper describes NWAC’s array of data, observational results, and analytical techniques that make “avalanche weather” forecasting possible. In addition, NWAC’s operational program and the general terrain and climate of the area are described. A sample forecast is also included.

Inclinometry with embedded probes is analyzed with a Stokes model of a solid body floating in a fluid with much smaller viscosity for a two-dimensional flow field. The assumption that such a probe behaves like a Lagrangian unit vector is only justified for probes embedded in a Newtonian fluid with lengths at least four times their width. A fluid with Glen-type rheology results in a slightly smaller rotation rate of the probe compared to Newtonian fluids.

Eight different ice budgets for the Antarctic Ice Sheet are examined. Five of these budgets call for rates of increase of the ice which are in surprisingly good agreement considering the wide dispersion of individual components of the budgets. The observed rise in sea-level of the world’s oceans would appear to contradict the removal of water required to nourish the Antarctic Ice Sheet at the claimed rates. The thermal expansion of oceanic columns, caused by “climatic” warming of the oceans, has been invoked to resolve this contradiction but it appears that this is not large enough judging from the 30 yr. difference in water temperatures measured by the Meteor and the Crawford in two profiles across the tropical Atlantic Ocean.

Ice originating near the inland ice divide of the ice sheet can reappear as marginal ice at the surface near the ice terminal in the ablation area. We have analyzed δ18O values and ion concentrations of the Skallen, Skarvsnes and Hamna terminal ice sections, located along the estuary line in the Sôya drainage basin, East Antarctica. The data suggest that the upper part of the Skallen terminal ice section could have originated from inland precipitation on the Shirase drainage basin during marine isotope stage (MIS) 5e, while the upper part of Skarvsnes and Hamna terminal ice sections could have originated from inland precipitation on the Sôya drainage basin. We calculate past elevation maps for the Antarctic ice sheet using the three-dimensional model, SICOPOLIS. This model suggests that the upstream portion of the Sôya drainage basin during the glacial period (MIS 2, 3 or 4) was located to the northeast of its present location. A flow history is proposed wherein ice from the inland Shirase drainage area flowed over the present ice-divide line from the Shirase to the Sôya drainage basin during the glacial period. The ice in the Sôya drainage basin then flowed to the marginal part of the sheet after the ice divide had assumed its present position.

On the Ross Ice Shelf near Scott Base the annual surface snow accumulation is about 18 g.cm.−2. The increase of firn density with depth is greater than normal, due to horizontal compaction. Where the bottom of the ice shelf has a density less than 0.8 g.cm.−3 the shelf becomes brine-soaked by vertical infiltration. The bottom of the shelf is melting, at about 44 g.cm.−2 yr.−1 where the bottom is impermeable ice and 73 g.cm.−2 yr.−1 where the bottom is permeable firn. Surface velocities at 40 points within 30 km. of Scott Base vary between 4 and 840 m.yr.−1. From the pattern of velocities, ice thicknesses and surface features, a transition zone is delineated, separating the Ross Ice Shelf from the “McMurdo Ice Shelf”.

The hypothesis that ice-sheet evolution is only controlled by the long-term non-Newtonian viscous behavior of ice has been challenged by observations indicating that effects like brittle failure, stick-slip sliding, tides and wave action may affect ice-sheet evolution on sub-daily timescales. Over these timescales, the quasi-static-creep approximation is no longer appropriate and elastic effects become important. Simulating elastic effects in ice-sheet models over relevant timescales, however, remains challenging. Here, we show that by including a visco-elastic rheology and reintroducing the oft neglected acceleration term back into the ice-sheet stress balance, we can create a visco-elastic system where the velocity is locally determined and information propagates at the elastic wave speed. Crucially, the elastic wave speed can be treated like an adjustable parameter and set to any value to reproduce a range of phenomena, provided the wave speed is large compared to the viscous velocity. We illustrate the system using three examples. The first two examples demonstrate that the system converges to the steady-state viscous and elastic limits. The third example examines ice-shelf rifting and iceberg calving. This final example hints at the utility of the visco-elastic formulation in treating both long-term evolution and short-term environmental effects.

A model, relating spatial patterns of snow accumulation in the alpine belt of major mountain ranges to the angular relationship which exists among terrain features such as cirque basins, mean storm-path trajectories, and incident solar radiation, is presented together with a limited amount of relevant empirical data. It is suggested that an “orientation gradient” exists in both the temporal and spatial variation of accumulation and ablation in the alpine terrain, the importance of which varies as some function of the relative control exerted by wind redistribution of snow and of direct incident solar radiation on the accumulation and ablation processes. The data obtained to date suggest that the importance of the orientation gradient varies widely among the mountain ranges studied, being a good predictor of snow distribution patterns in the Front Range of the Colorado Rockies and the Snowy Range in southern Wyoming, both of which are relatively windswept, while in the much less windy Bridger Range, in south-western Montana, both orientation and elevation appear to contribute on an almost equal basis. An indirect method of estimating relative amounts of annual mass turnover, using eleven glaciers located in the Wind River of west central Wyoming, is presented.