Effect of lightning activity on surface NO x and O 3 over a tropical station during premonsoon and monsoon seasons

We study the effect of lightning activity on surface NO x and O 3 over Pune, India (18.54°N, 73.81°E) for the years 2005 to 2008 during thunderstorm events in premonsoon and monsoon periods. Surface concentration of NO x is found to be increased significantly at the dissipation stage of thunderstorms. It is observed that increase in NO x greater than titration threshold level reduces the surface ozone concentration. However, in some cases when NO x increases but it does not reach the titration threshold limit, it helps in the production of ozone. Thus, results suggest that lightning production of NO x inside a thunderstorm can lead to significant impacts on surface ozone concentrations in the tropics. Enhancement in NO x at the surface after thunderstorm activity is much greater in premonsoon periods compared to the monsoon period.