Validation of 3 years of ozone measurements over network for the detectionof stratospheric change station Lauder, New Zealand

A large number of ozone profiles measured by using various methods (lidar, ozonesondes, microwave radiometer, and Stratospheric Aerosol and Gas Experi ment II) over Lauder, New Zealand, between late 1994 and early 1998 are int ercompared. These profiles are also used to validate a collocated Dobson sp ectrophotometer. Between March 1996 (August 1996 for sonde measurements) an d January 1998, all instruments were operational and no instrument changes took place. The ozone number densities averaged over this period agreed wit hin 5% in the 20- to 35-km range. Between 12 and 20 km, lidar and sonde res ults deviated by less than 8%, and lidar and SAGE II results deviated by le ss than 15%, The ozone column densities measured by the Dobson spectrophoto meter agreed within 3% with the integrated ozone profiles. The various meth ods are discussed, and modifications are proposed. They comprise a decrease of the reported sonde altitudes of about 125 m (+/-50 m) to correct for th e response time of the sonde's chemical solution, the use of more accurate molecular parameter values in the lidar algorithm, and a 2.5% decrease in S AGE II ozone densities. Improved agreement between the average ozone profil es to within 1.5% for lidar and sondes (20-35 km) and within 2.5% for lidar and SAGE II (20-35 km) is achieved. The Dobson results are found to be inf luenced by the annual cycle of the temperature profile through the altitude -averaged ozone absorption cross section, which has been assumed to be cons tant in the presented data but actually varies with an amplitude of 2% over Lauder.