No abstract

Snow movement in polar areas creates problems for surface (at-grade) camps, particularly in areas of net annual snow accumulation. Snowdrift studies, which were made over a 4-year period around a single unprotected building and around a cluster of buildings in an area of net annual snow accumulation on the Ross Ice Shelf near McMurdo Station, Antarctica, showed that at-grade camps will eventually become covered with drifting snow. Drift control measures, however, can be used to increase the usefulness and life of such camps. The measures developed cover proper building orientation and camp layout with respect to the major storm winds. In addition, mobile foundations may be used for buildings to facilitate camp moves when snowdrift becomes excessive.

A study of thickness, density, and salinity of various ages of sea'ice on McMurdo Sound, Antarctica was conducted during the summer season of Deep Freeze 62. During the sampling period, the 1-and 3-year ice decreased in thickness about 3 feet on the bottom; no loss occurred in the older 30-foot thick ice. The sampling interval of 4 to 5 weeks at 3-to 5-foot depth intervals was too great to permit the development of summer trends in salinity, density and strength.Because of the lack of knowledge on the characteristics of antarctic sea ice, further sampling of natural and flood produced ice in McMurdo Sound are planned by the Laboratory. INTRODUCTIONAntarctica is surrounded by sea ice at least nine months of the year; in some areas, the ice may persist for several years befor moving out to sea.Aircraft operations on this ice tend to be limited in scope and time because of the unstable nature and the limited knowledge of the ice.Numerous investigations have been conducted on the properties of arctic sea ice and the feasibility of producing stable sea ice platforms by the surface thickening technique of free flooding. 1 ,2 ,3 No similar work, however, has been done on antarctic sea ice. Preliminary to a study of ice thickening techniques for Antarctica, an investigation of some physical properties on various ages of sea ice in McMurdo Sound were made during the summer of Deep Freeze 62. The site of these investigations was in the vicinity of McMurdo Station. Site Selection iThe age of the 30-foot thick sea ice under Williams Field was known only to be at least 7 years old. The area to the east of Williams Field was covered with younger ice, Little other information was available as to the age of various areas of sea ice near McMurdo Station bu t from depth measurements, one area was estimated to be 3 years old and an adjacent ice area was known to be one year old. They were located about 2 miles southeast of Cape Armitage and 1/2 mile from the face of the Ross Ice Shelf. These two areas and the old ice at Williams Field were sampled at 4-to 5-week intervals between November 1961 and February 1962. At Williams Field the samples were obtained along the northern edge of the runway. WeatherThe daily maximum, minimum and average mean temperatures for the Deep Freeze 62 sumer season (October-February) at Scott Base, which is located at the edge of the Ross Ice Shelf near the sampling areas, is shown in Figure 1.During the sampling period the average mean temperature, which was obtained from hourly readings, ranged from about 5 r in early November to about 25 F in early January. SAMPLINGA lightweight sled mounted laboratory was used to test the core samples as soon as they were extracted from the ice.Three cores were taken at all sampling stations each sampling period. These were used to obtain the average salinity, density and strength at selected depths. EquipmentCoring and test equipment was housed in a lightweight 5-by 8-foot plywood shelter mounted on a 1-ton sled. This mobile laboratory, which was moved fr...

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During the spring of 1962, the U. S. Naval Civil Engineering Laboratory, Port Hueneme, California conducted trials at Point Barrow, Alaska on the deterioration, ablation and some physical characteristics of natural and constructed sea ice. Although deterioration occurred throughout the ice sheet, ablation occurred only at the surface. Observations on temperature, salinity, density and crystal orientation of these two ice types showed that the average ice temperature for the total ice thickness was about the same for an undisturbed natural ice area as for a constructed ice area. It was found that the high salinity of constructed ice did not greatly affect the salinity of the underlying natural ice and that with time the salinity and density of the constructed ice approached that of natural ice. Also it was observed that the preferred C-axis orientation of sea ice is towards the horizontal, although snow and wind influence a random orientation and crystal size.It was concluded from these trials that prevention and reduction of ablation during thaw should improve the characteristics or sea ice, but further knowledge is needed to determine the influence and effect of the size and C-axis orientation of the ice crystals. Improved field sampling and testing techniques are needed to obtain more accurate knowledge of the properties of ice.Qualified requesters may obtain copies of this report from ASTIA.The Laboratory invites comment on this report, particularly on the results obtained by those who have applied the information.