Long-term trend of ozone column over the Indian region

Ozone observations taken during the past 23-45 years by Dobson spectrophotometer at six stations of India have been analyzed to examine its long-term trend over this subcontinent. These stations are Kodaikanal (10 degrees N, 77 degrees E), Pune (18 degrees N, 74 degrees E), Mount Abu/Ahmedabad (24 degrees N, 72 degrees E), Varanasi (25 degrees N, 82 degrees E), New Delhi (28 degrees N, 77 degrees E), and Srinagar (34 degrees N, 74 degrees E). An increasing trend of this species over the years has been noticed at all the places, except at Varanasi, where a decreasing Vend has been found. The Nimbus 7 total ozone mapping spectrometer data at all the six stations have been compared with the Dobson data. Goad agreement is found at all the stations except at Kodaikanal and Ahmedabad. The cause of these trends could be attributed, partly, to the trends of ozone in the troposphere.