Variability in the vertical distribution of ozone measured over Thumba during the 1990 DYANA campaign

A rocket campaign was conducted from Thumba (8.5°N), India, jointly by India and Russia, to study the vertical distribution of ozone during the International DYANA programme in 1990. Sixteen instrumented payloads were launched using M-100 rockets to measure the vertical distribution of ozone at different times of the day and night during the March–June 1990 period. The ozone density profiles measured during March–April show variabilities in the height region below 25 km and above 45 km. The profiles on 10 April show wave-like perturbations with amplitude increasing with height. The mean ozone density profile for March–April shows larger values than the May–June mean profile in the altitude region of 30–45 km. The deviations from the mean reference profile during March–April are positive, about 15%, while they are negative, about 25%, in May–June. Ozone number densities are also found to be larger during the night-time at altitudes above about 50 km. The observed increase is larger than the model estimates.