High ozone episodes and their association to stratospheric intrusion over Northeast India

Surface ozone measurements in the northern hemisphere till date have found spring maximum. This spring maximum is a combined effect of photochemical production from anthropogenic emissions of precursors and intrusion of stratospheric air with high concentrations of ozone but quantification of contribution from each of these processes is still uncertain. Strong stratospheric intrusion have been observed in the month of April over 25-30 N latitude accompanied by intrusion of ozone rich air into the troposphere. Ground measurements also show higher ozone concentration (> 40 ppb) near the surface. Observation of CO (carbon monoxide) is used to delineate the convective outflow of ozone and its precursors or contribution from biomass burning.