GLOBAL OZONE DEPLETION AND THE ANTARCTIC OZONE HOLE

The secular trend of the Antarctic ozone hole has been studied with a two-dimensional model which can simulate formation of polar stratospheric clouds and includes heterogeneous chemical reactions. Results from the numerical simulation have been validated by comparison with available experimental data. Trends up to the year 2010 using standard (i.e., homogeneous) and heterogeneous chemistry have been compared and show that global ozone depletion reached 5-6% in the last 30 years and will average 8% for the next 20 years. Subtracting a 2% loss due to standard chemistry in the presence of trace gas increase in the last 30 years, we find a 3-4% global ozone loss -due to heterogeneous chemistry. The depletion is evident even outside the southern hemisphere spring season and at mid-latitudes, pointing to an increase in global ozone sink.