Measurement unit of ozone?

Atmospheric ozone is measured by various methods and also by using various instruments. Ozone is measured in Dobson units (DU).

Different types of measurements used to measure ozone in the atmosphere are ground based measurements, air-borne measurements and satellite measurements.  

*Dobson spectrophotometer is the earliest instrument used to measure both column ozone and profiles of ozone in the atmosphere.

*LIDAR ( Light Detection and Ranging )  is a technique  used to measure ozone. This depends on absorption of laser light by ozone.

*Ozonesonde includes a ballon carrying the instrument upto 21 miles high into stratosphere to measure ozone.

*Rockets are used to measure level at an altitude of 75 km.

*Satellites are used to measure the ozone over the entire globe.  e.g. TOMS is one such aid to measure ozone.