Influence of Stratospheric Intrusion on the Surface Ozone Levels in India

The surface ozone levels in some Indian cities have increased significantly in the recent years. Ozone being toxic to the living system and an important contributor to anthropogenic global warming, enhanced surface ozone may have adverse effects on the air quality and climate. Transport of ozone from the stratosphere to the troposphere causes stratospheric ozone to decrease and tropospheric ozone to increase, which can in turn have serious consequences for life on earth. Since stratosphere-troposphere exchange (STE) is an important factor influencing the ozone concentration in the troposphere, this paper investigates probably for the first time the possible contribution of STE events to the observed enhanced surface ozone levels for cities covering from north to south of India. It is concluded that apart from transport processes and in situ photochemical production, STE also influences the observed high-surface ozone levels in Indian cities to a small extent (8%–16%). STE events producing high-surface ozone levels are found to be higher at high latitudes.