The total ozone content over Bulgaria during the solar eclipse on 11 August 1999

Summary form only given. The ozone is a very important component in the Earth atmosphere as far as the radiation processes are concerned. The solar eclipse affords an opportunity to investigate the ozone reaction when the solar irradiation changes significantly and comparatively quickly. The total ozone content (TOC) during the solar eclipse (the maximum coverage was 96%) has been measured by the Photon-2 spectrophotometer. The device measures the direct solar irradiation in the range 300-340 nm at 1 nm spectral resolution. It has been calibrated by comparison to the Brewer spectrophotometer in Thessaloniki, Greece, in 1997. The TOC computation has been made by comparing different irradiation wavelenghts. Having in mind the quick temperature change during the solar eclipse, wavelenghts have been used, whose cross sections depend slightly on the temperature. The previous data analysis for the ozone behaviour during the eclipse shows that the TOC change approximately 15% mainly after the maximum phase. This result can be slightly modified taking into account some factors as the dark limb effect, for example