Abstract
The results of the intercomparison between Dobson spectrophotometer No. 118 operating in Athens, Greece and the Reference Instruments Dobson No. 065 and No. 064 in the period 1990–2006 is presented. The Athens Dobson spectrophotometer participated in the Dobson intercomparison campaigns held at Arosa, Switzerland (1990), Kalavryta, Greece (1997) and Hohenpeißenberg, Germany (2006). The results obtained at Arosa showed a deviation of 0.03% in total ozone observations, whereas at Kalavryta and Hohenpeißenberg the highest deviations were –0.4% and 0.6%, respectively. Hence the Dobson spectrophotometer installed in Athens since 1989 can be regarded as a reliable ground-truth station that can be used for the validation of satellite ozone observations and the study of trends in total ozone content (TOC).