Annual Cycle of Tropical and Subtropical Total Columnar Ozone and Its Decadal Variability

Total columnar ozone (TCO) variability is studied over tropics (0N-25N, 65E-95E) and subtropics (25N-45N, 65E-95E) for the period 1979-2012 (except data gap 1993-96) using satellite data. Annual cycle of TCO is examined. The maximum values of TCO over tropics are found in the summer whereas the maxima values over subtropics are in the winter season. Seasonal variation in subtropical TCO shows higher gradient (140 DU) than that of the tropical TCO (gradient is 60 DU). The conclusions arrived over tropical and subtropical region are found to be valid over micro scale domain as seen from the analysis over smaller region surrounding Thiruvananthapuram (7.5N-9.5N, 75.6E-78.1E), Pune (17.5N-19.5N, 73.1E-74.4E) and Delhi (28.5N-29.5N, 76.9E-78.1E) using same satellite data sets for 30 years. Further, the seasonal behavior of TCO over global tropical (0N-25N) and subtropical (25N-45N) domain are not affected by changing longitudinal belt.