Ozone measurements in the tropics

Abstract

The discovery in 1985 of the ozone hole over the Antarctic and recent reports of ozone depletion over the Arctic have led to a serious, world-wide concern of possible damage to the ozone layer that shields the biosphere from the lethal ultraviolet radiation from the sun. Statistical analysis of the long-term measurements of the global average of column ozone has, however, shown no significant fall in total ozone with time (UKSORG, 1987). But the Ozone Trends panel established by the U.S. Aeronautics and Space Administration (NASA), the U.S. National Oceanic and Atmospheric Administration (NOAA), the U.S. Federal Aviation Administration (FAA), the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO), reported a small but detectable stratospheric ozone reduction in the Northern Hemisphere and identified chlorofluorocarbons (CFCs) as possible contributors to this reduction and as the most likely primary cause of the drastic springtime ozone depletion over the Antarctic (Watson et al, 1988). Regular measurements of total ozone and its vertical distribution in the atmosphere, using Dobson ozone spectrophotometers, have been made at a network of six stations in India since the International Geophysical Year, 1957. The data recorded in the Indian network, as well as at 21 additional stations in the tropics from 30°N to 30°S, were examined to see whether the processes, which give rise to the ozone depletions in the Antarctic and Arctic regions, affect the tropical latitudes. An analysis of the available data has shown no significant trend of ozone depletion in the tropics in the last three decades.