Variation in tropospheric ozone concentrations over different stations in India

The paper presents the nature of variations of tropospheric ozone retrieved from the convective cloud differential (CCD) technique over different stations in India, namely, Trivandrum (8.25°N, 76.9°E), Bangalore (13°N, 77.5°E), Hyderadabad (17.25°N, 78.5°E), Dumdum (22.5°N, 88.5°E), Varanasi (25.5°N, 83°E), New Delhi (29°N, 77°E) and Srinagar (34°N, 74.8°E) from October 2004 to September 2015. Monthly variations of monthly mean tropospheric ozone clearly reveals that though oscillatory it had enhanced slowly from October 2004 to September 2015 over all the above stations. Yearly variations of monthly mean concentrations of tropospheric ozone for different months depicted the increasing trends over all stations except January, February and August mean values over Trivandrum, February values over Dumdum, March values over Varanasi, March, April and November values over New Delhi and Srinagar. Yearly mean tropospheric ozone gradually increased from 2005 to 2014 over the all stations with different rates. Yearly variations of seasonal mean tropospheric ozone concentrations reveal gradual slow growth of winter, pre-monsoon, monsoon and post-monsoon tropospheric ozone over all the above stations except the stations Trivandrum and New Delhi for winter and pre-monsoon variations of tropospheric ozone, respectively for the above period. Annual cycles and seasonal variations of tropospheric ozone concentrations occurred the maximum in the months of April and May during pre-monsoon season and the minimum in the month of August during monsoon season. Monthly mean tropospheric ozone concentrations had increased with rise in latitude in Indian region.