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 +/- 4.2 DU) 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 (similar to 51 +/- 2.3 DU) than over the central (similar to 47 +/- 3.2 DU) and eastern parts (similar to 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 (similar to 22 DU) than over the central (similar to 18 DU) and eastern parts (similar to 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.