Diurnal and seasonal variation of columnar ozone at Rajkot

Abstract

Ozone data obtained from Earth-Probe Total Ozone Mapping Spectrometer (TOMS) has been used to calibrate a Microtops-II Sun photometer. Results of observed diurnal and seasonal variation of ozone at Rajkot, obtained using Microtops-II Sun photometer is reported. Since the ozone concentrations measured by Dobson spectrometers in India and TOMS are found to correlate well, it is possible to calibrate Microtops-II Sun photometer with the help of TOMS to get accurate ozone values over Indian low latitudes. This will in turn reduce the inconvenience of carrying the Microtops Sun photometer to a Dobson center for calibration. The diurnal variation of ozone measured by Microtops-II Sun photometer indicates a higher vertical column density of ozone during morning compared to evening hours. This may be due to an increase in daytime temperature and the corresponding increase in ozone by photolysis. An examination of the monthly mean ozone values obtained from Microtops-II Sun photometer indicates a marked seasonal variation with a maximum ozone concentration around June and a minimum around December.