Graph showing minimum levels of Antarctic ozone in Dobson Units (DU) from 1979 to 1996. (From Ministry for the Environment) A Dobson Unit is a basic measure used in ozone research. It is named after G.M.B. Dobson, who designed the 'Dobson Spectrometer' - the standard instrument used to measure ozone from the ground. The Dobson spectrometer measures the intensity of solar UV radiation at four wavelengths, two of which are absorbed by ozone and two of which are not. For more on the Dobson Unit go to: Total Ozone Mapping Spectrometer.