Ozone concentration studies near the ground at Poona- Part I: Diurnal, seasonal and other time variations and ozone flux measurements

Abstract

Using a Brewer bubbler ozone sensor, designed and developed in the Instruments Research Laboratories of the India Met. Dep. continuous measurements of ozone concentration near the ground were made at Poona (18°N, 73°E) for one year 1969,70. There is a marked diurnal variation in surface ozone concentration which clearly follows the diurnal variation of temperature and is again a maximum during the pre-monsoon hot season months and a minimum during the monsoon. The surface ozone concentration also shows a pronounced seasonal variation, with a minimum during the monsoon months and a maximum during the pre-monsoon hot weather months. A secondary maximum in ozone concentration occurs in the forenoon during the winter months, associated with the breakdown of temperature inversion that occurs near the ground.

From continuous measurements of surface ozone made with three electrochemical sensors exposed at three levels, 0,15 and 35 m above the ground, the ozone flux was calculated using the rate of decay method used by Kroening and Ney, and Regener's profile method. The profile method gives values of 1. 71 to 7. 04X 10¹¹ mol/cm²/sec and the rate of decay method gives 4.2 to5.6 x 10^l1mol/cm²/sec which are in good agreement with the flux values reported by other investigators.