LONG-TERM TRENDS IN TOTAL OZONE OVER SOUTH ASIA AS OBSERVED BY SATELLITES (TOMS AND GOME)

摘要

The breakdowns of stratospheric ozone by man made halogenated chemicals are known to be responsible for ozone depletion observed at poles and mid-latitudes. Total Ozone measurements from NASA's Total Ozone Mapping Spectrometer (TOMS) and from Global Ozone Monitoring Experiment (GOME) on Earth Resource Satellite (ERS-2), for July 1995 to Dec. 1997 and for the year 2000 were used to determine the quantitative spatial and temporal resolution of ozone over the region. The study was also aimed at quantitative evaluation of ozone data derived from TOMS and GOME. Daily total ozone observations made by these satellites over South Asian region (Dhaka(23.45°N, 90.29°E), Dehli (28.18°N, 77.30°E) , Karachi (24.53°N, 67.02°E), Tehran (35°N, 51.03°E), Chitral (35°N, 71°E), Lahore (31.34°N, 74.19°E) and Quetta (30.12°N. 67.01°E)) . Long term trend estimates obtained from the linear regression analysis show significant positive ozone trend in the southern latitudes ranging from+15.6% to 15% (Dhaka, Dehli and Karachi) over the study period. However, the measurements for mid latitudes (Tehran, Chitral, Lahore and Quetta) have shown significant negative trend of-15% to ―1.3% in total ozone.