On some aspects of tropospheric ozone variability over the Indo-Gangetic (IG) basin, India

To study tropospheric ozone variability over the Indo-Gangetic (IG) basin, monthly tropospheric ozone residual (TOR) data has been analysed for the 1979-2004 period. Tropospheric column ozone has been observed to have a maximum during late summer (48±4.1 DU) and a minimum during late winter (30±4.2DU)over the IG basin. The amplitude of the seasonal cycle has been observed to be comparatively larger over the western part of the IG region (~51±2.3DU) than over the central (~47±3.2 DU) and eastern parts (~47±3.2 DU) of the region. Similarly, the seasonal variation in tropospheric ozone has been observed to be comparatively larger over the western part of the IG region (~22 DU)than over the central (~18 DU) and eastern parts (~17 DU) of the region. The difference in tropospheric ozone amount over the eastern and western parts of the IG region also shows seasonal variation with a large difference (up to 4 DU) during the monsoon season. The monsoon system plays an important role in the seasonal variation of the tropospheric ozone over the different parts of the IG region