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Abstract
During the annular (87.6%) solar eclipse of May 20, 1966, more than 60 measurements of total ozone were taken with the Dobson ozonespectrophotometer at the University of Sofia, Bulgaria. An analysis of data obtained shows an ozone increase of 25–30 m atm-cm (Δ Ω 2σΩ) at the maximum phase of the eclipse. However, according to the photochemical theory, only ~1 m atm-cm increase should occur during an eclipse such as this.
The difference between the theoretical and observed increase of the total ozone may be partly due to the limb-darkening effect. The importance of this effect increases progressively to the maximum phase of the eclipse. When dark-limb correction is applied to observational data, the ozone increase is reduced to 14 m atm-cm (about 4 per cent of the total ozone amount). This increase is as yet unexplained.