SEA ICE STUDIES ON MCMURDO SOUND DURING DEEP FREEZE 65.

The sea ice adjacent to McMurdo Station, Antarctica, has been used extensively since 1956 for aircraft operations, travel, freight hauling, and loading and unloading ships. A study of some factors affecting the safety and efficiency of these operations was made during the summer of 1964-65. The factors included cracks, seal holes, pressure ridges, and breakout of the ice in this area at the end of the 1964-65 summer season. It was found that cracks which did not penetrate the ice sheet, and seal holes in thick ice did not seriously affect the bearing capacity of the ice; however, flooding in pressure zones and around seal holes on the ice sheet created a hazard to travel where the ice was covered with snow. In addition, it was observed that breakout of the ice south of McMurdo Station began about 3 weeks after the ice exhibited minimum strength, maximum temperature, and a rapid decrease in thickness, and 4 to 6 weeks after maximum daily air temperatures were observed at McMurdo Station. It was concluded that additional research is needed to provide adequate knowledge on the influence of those factors affecting the safe and efficient utilization of sea ice in Antarctica.