| Summary: | In 1989 the Total Ozone Mapping Spectrometer (TOMS) aboard the Nimbus 7 satellite observed the springtime decrease in Antarctic total ozone for the 11th consecutive year. The 1989 minimum values of total ozone measured by TOMS declined throughout the month of September at a rate nearly identical to 1987. The area of the ozone hole as defined by the 220 DU contour grew rapidly during early September. It reached a mid-September peak of 7.5 percent of the Southern Hemisphere, or 19 million square kilometers, essentially the same as observed in 1987. From mid-October through November 1989, minimum polar total ozone values increased and the area within the 220 DU contour decreased more rapidly than during the comparable period of 1987. The more rapid erosion of the 1989 ozone hole resulted from strong wave number one perturbations of the vortex dynamics in late October.
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