Ozone is a naturally occurring chemical consisting of three oxygen atoms and is predominantly found in a layer of the atmosphere beginning at about 10km above the surface of the Earth with a peak in concentration at about 22km. It's important to life on earth because the ozone layer absorbs all Ultra Violet C radiation from the sun which is very dangerous to all life. It also absorbs most of the Ultra Violet B radiation which causes skin cancer and cataracts in people and damages crops and the ecosystem, particularly aquatic lifeforms.
A hole in the ozone layer was discovered at Halley Station, Antarctica, in 1985 by three British scientists and it still exists today. It changes seasonally and forms in late winter and lasts through out the spring. Sometimes it can be very circular and centred over the south pole and at other times it can be elongated or distorted and wobble back and forth over the pole. In 1987 the "Montreal Protocol On Substances That Deplete The Ozone Layer" was agreed and signed by every country in the world which lead to a phase out of ozone depleting substances. It was only in 2018 that an assessment made by the World Meteorological Organisation was ready to say that signs of improvement in the ozone hole were now starting to become evident.
Nearly every Wednesday morning since 2003 the Bureau of Meteorology (BoM) team at Davis have released an ozone sonde. An ozone sonde is an instrument that records the concentration of ozone in the air and is attached to a weather balloon. As the balloon ascends up through the atmosphere the ozone sonde continually records the concentration of ozone at all heights from the surface to about 35km where the balloon bursts. The data is transmitted back to the weather station where an ozone vertical profile is created. The ozone vertical profile is a graph that illustrates the important features of the ozone layer such as where it begins, how thick it is and where the highest concentration of ozone is. This is analysed by BoM staff in Melbourne and shared with other meteorological organisations globally. The processed data is sent to the World Ozone and Ultraviolet Data Centre in Canada, from where it is permanently available for international scientific study.
The Davis ozone sonde program is very important because most long term records of ozone are from the northern hemisphere. Davis is one of only a very few long term sites in the southern hemisphere and the only Australian site on continental Antarctica. The BoM also release ozone sondes from Macquarie Island and Broadmeadows in Victoria.
The Altitude Profile graph shows the concentration of ozone at different altitudes for all the sondes released since the beginning of this year. Note the peak in ozone concentration centred at about 22km. The Annual Cycle graph shows the amount of ozone where the layer is the thickest for the whole year dating back to when records began. Note the low ozone levels in spring when the ozone hole is over Davis Station.
Craig Butsch - Bureau of Meteorology - TO3 Observer
