Satellite measurements of ozone have been made since the launch of the Backscatter Ultraviolet (BUV) instrument on the United States Nimbus-4 satellite in 1970 [Heath et al., 1975]. Subsequent instruments, using the same measurement technique as the Nimbus-4 BUV instrument, have been providing total ozone measurements nearly continuously since that time. These instruments provided quantitative information about the total amount of ozone between the earth's surface and the satellite and primarily provide scientists with information about the distribution of ozone in the stratosphere since ~90% of the ozone in the atmosphere lies in this region (~15 km - 55 km). The remaining ~10% is located in the troposphere; the boundary between the troposphere and the stratosphere, the tropopause, is generally located at an altitude between 12 km and 18 km and varies as both a function of latitude and time of year. In the tropics, the tropopause is located higher in the atmosphere (16-18 km) than at middle latitudes, where the height of the tropopause can be as low as 8-10 km, or as high as 15-16 km, with higher tropopause heights generally found in the summer.

The amount of ozone in a column of air is expressed in units called Dobson Units (DU) where one DU has a value of 2.69 x 10e16 molecules of ozone cm-2. A representative amount of total ozone in the atmosphere is 300 DU, of which ~30 DU is in the troposphere and the remainder is in the stratosphere. In the unusual occurrence of the "ozone hole" found over Antarctica during austral spring, total ozone values <100 DU have been measured.