The radar antenna sits inside the tire tube and is pushed across the surface of the snow by a Tucker.
Preparing to drill an ice core.
Studying Ice Cores
Ice cores drilled from the ice sheet provide a sample of all the layers of snow accumulated over thousands of years, the oldest at the bottom. Choosing a site to drill from can be just as important as the core that is recovered. Many factors are considered including the shape of the underlying bedrock and the height of the ice sheet. Radar antennae are use to survey the ice sheet. They provide very accurate calculations of the depth and surface contours of the ice as well as pinpoint the location of dangerous crevasses. Once a site is selected, a drill is set up and the coring begins. Mechanical drills can penetrate up to 3 feet (1 m) at a time before being withdrawn for the core to be recovered. To reach the 200 year depth, the team will have to drill 160-230 feet (50-70 m) which will typically take about a day. There are plans to drill cores as deep as 650 feet (200 m) to get longer records. Those cores will take three to four days to drill.
Ice cores are usually about 3 inches (10 cm) in diameter. As they are brought to the surface a scientist will examine the core and attempt to place that section of core in time. Alternating bands of light and dark snow can been seen when light is shone through the ice core from behind. The light layers represent summer snow and the dark layers are winter snow. By keeping track of the individual layers they can be counted in much the same way as tree rings. More sophisticated techniques for dating ice cores are done later back in the labora tory by analyzing the concentration of oxygen atoms in the ice.
Climatic parameters such as air temperature, precipitation rate, and solar radiation can be interpreted from ice cores. By studying this record, scientists can identify the natural cycles in
global warming and cooling.