No. 45: May-Jun 1986
Reviewing ozone-mapping data from the polar-orbiting Nimbus-7 satellite, R. Stolarski and colleagues at NASA's Goddard Space Flight Center have seen the concentration of ozone over Antarctica drop dramatically -- some 40% -- every October. This disappearing act commences about a month after the sun begins to graze the northern horizon and affects the entire continent. By early November, the sun is high enough to manufacture enough ozone via its ultraviolet radiation to fill the ozone hole up again. An analogous hole does form over the North Pole in the northern spring. An additional fact of interest: the hole is getting deeper each year; that is, the ozone concentration is less and less each October. Speculations about the deepening seasonal hole involve the widespread use of chlorofluorocarbons and Antarctica's physical isolation from other land masses which would help channel ozone southward from areas where the sun still shines.
(Weisburd, S.; "Ozone Hole at Southern Pole," Science News, 129:133, 1986.)