Trend analysis of Total Column Ozone over New Delhi, India

Total Column Ozone measurements from Total Ozone Mapping Spectrometer (TOMS) onboard satellite Nimbus 7, Meteor 3 and Earth Probe have been used to determine trends in column ozone over New Delhi. Long term trend obtained with ozone time series data and least square fitting without removing Seasonal cycle, QBO, Solar effect and ENSO, shows that ozone concentration is decreasing by 2.11 (+/- 1.04) % per decade over New Delhi. Therefore, to calculate the exact trend, multifunctional regression model have been used to remove the effect ofseasonal cycle, solar cycle, QBO and ENSO. The obtained long term trend with multifunctional regression model shows that column ozone over Delhi is actually decreasing by 1.83 (+/- 1.02) % per decade. The trend obtained from ozone time series data with least square fit overestimates multifunctional regression model by about 15%. The objective of this paper is to present the result of a long term trend analysis of the TOMS total ozone data over New Delhi.