Solar eclipse induced changes in surface ozone at Ahmedabad

摘要

Measurements of surface ozone and related gases were made at Ahmedabad during the solar eclipse of 24 Oct. 1995. The maximum obscurity at Ahmedabad was 79.2%. The diurnal increase in ozone concentration due to photo-oxidation of pollutants like CO, CH_4 and non-methane hydrocarbons (NMHCs) observed on normal days after the sunrise was not observed until the time of maximum obscuration. In fact, there was a decrease in ozone concentration in the range of 18-21% at the maximum phase. Ozone levels were found to be lower even after the eclipse due to loss and delay in ozone production. The eclipse conditions were simulated in a photochemical box model which was used to calculate ozone changes. The model shows a decrease of ozone by about 16% as compared to a control day at the time of maximum obscuration. The model also shows significant role of boundary layer variations in the morning hours.