Short-term ground ozone fluctuations at Poona

Abstract

Short-term fluctuations superimposed on the diurnal variations of surface ozone recorded at Poona during 1969–1970 are discussed.

While there is a net production of ozone during electrical discharges in a thunder cloud, the surface ozone recorder often registered a decrease in surface ozone concentration. This decrease coincided with updraughts generated during the formation of a thunderstorm. Similar sharp increases in ozone were observed with downdraughts. In cases of lightning without the development of a thunderstorm over the station, an increase in ozone density was observed just after the first lightning discharge.

Apart from the fluctuations associated with thunderstorms in summer, sharp fluctuations in density were also noticed during winter, in the mornings. Abrupt falls in ozone occur with the formation of a stable layer near the ground at night and a sudden surge after the breaking up of the layers in the morning. The changes in ozone are, however, much more pronounced than those in temperature and wind and this striking correlation between surface ozone, surface air temperature and wind provides a unique tool for the study of low-level temperature inversions, their establishment and destruction.