Greenhouse gas molecules such as carbon dioxide can trap energy radiated by the warm Earth and transfer it to other atmospheric gas species by collisions, effectively warming the atmosphere. These same greenhouse gas molecules can also collect energy from collisions with other atmospheric species and radiate that energy to space, effectively cooling the atmosphere.
Whether cooling or warming dominates, depends on the frequency of atmospheric collisions. Near the Earth, the atmosphere is dense and enhanced greenhouse warming results from increased carbon dioxide concentrations. Higher in the atmosphere collisions between molecules are less frequent and increased concentrations of greenhouse gasses cool the atmospheric regions.
Present understanding of atmospheric processes leads to predictions that at an altitude of about 85 km, cooling will result in temperature decreases three to six times greater in magnitude than the temperature increase near the Earth’s surface. We monitor the temperature of this region above Davis by measuring an airglow emission (light emission from an air molecule) that comes from a 10 km wide layer at this altitude. One aim is to determine if ‘greenhouse warming’ can be monitored more conclusively from this region of enhanced signal, well distanced from other human-induced changes that can influence local temperature records over the long-time intervals needed to confirm greenhouse change in the lower atmosphere.
Some evidence has been presented by other scientists that this region of the atmosphere is cooling much faster than predicted. If confirmed by measurements such as the ones we are making, our understanding of atmospheric processes will require some modification.
Australia has been collecting weather data in Antarctica since 1947. Today Australia’s Casey, Davis and Mawson stations maintain an upper air observational program using weather balloons. These observations provide data for research into Antarctic and global climate, and for assimilation by global and regional Numerical Weather Prediction systems, used by global and regional forecasters. The three stations are part of the World Meteorological Organisation Global Upper Air Network.
Automatic weather stations deployed at remote sites of the Australian Antarctic Territory also provide data for, among other things, the interpretation of climate data locked in ice cores, and for studies into surface wind processes over the ice sheet.
Davis station is a hub for research into ozone depletion and recovery. Radar and LIDAR instruments are used to study atmospheric phenomena that contribute to ozone depletion and also act as early warning indicators of climate change.