Impact of the solar eclipse of 15 January 2010 on the surface ozone and nitrogen dioxide concentrations at Kanyakumari, India

359-363Solar radiation derives the chemistry of the atmosphere. Solar eclipse, being a rare event, provides unique opportunities for studying the changes in the atmosphere due to the sudden reduction in the incoming radiation. The effects of solar eclipse of 15 January 2010 on surface ozone (SOZ) and nitrogen dioxide (NO2) at the coastal site, Kanyakumari (8o4’8’’N, 77o33’6’’E), Tamil Nadu, India, has been investigated in the present study. The behaviour of SOZ, NO2 and variation in meteorological parameters, like temperature, relative humidity (RH) were studied during this annular solar eclipse as well as one day before and after the eclipse. The experimental results showed that solar eclipse phenomenon affects the concentration of SOZ and NO2 as well as temperature and RH near the ground. Further, few minutes after the total eclipse, SOZ decreased to around 30 ppb, which is 25 ppb less than the normal and the level of nitrogen dioxide increased to 5 ppb. Also, it was noticed that during the course of the eclipse, the RH increased by 3% and temperature decreased by 4°C. The decrease in SOZ concentration was attributed to the reduction in the incoming solar radiation that affects the photochemical reaction. The observed increase in the NO2 concentration may primarily be due to the low photolysis rate of NO2