How is ozone measured?
Australia takes part in the Global Atmosphere Watch (GAW) international monitoring and research program coordinated by the World Meteorological Organization (WMO). The Bureau operates a network of ozone monitoring stations, where the total amount of ozone above the station (the total column ozone) is monitored each day. The total column ozone is measured with an instrument called a Dobson spectrophotometer, compares the amount of sunlight at two ultraviolet wavelengths. One wavelength is affected strongly by ozone, the other is not. The difference between the two is directly related to the total column ozone. Polar orbiting satellites are now used now give a map of total column ozone over the entire globe. The Dobson spectrophotometers are used to check the results from the satellites, to extend existing long records of ozone monitoring (up to almost 40 years), and to provide a near simultaneous reference measurement for vertical profile measurements using ozonesondes. To get the verti
