Observations of Ozone Depletion Associated With

rates of the various species. We can gain valuable insight into the chemistry by observing the response of ozone to changes in individual species. Gradual changes, such as those caused by the introduction of chlorofluoromethanes, are dicult to distinguish from the normal background variability and require accurate long-term monitoring pro- grams for accuracy. But during a solar proton event NOx (N, NO, and NO2) and HOx(H, OH, and HO2) are produced very rapidly (during the hours of the event itself) and in a limited area of the globe (above about 60 o geomagnetic latitudes), and this signature makes the resulting changes in ozone relatively easy to identify. SPEs (solar proton events) there- fore act as natural 'experiments' that can be used to check elements of the stratospheric chemistry problem. The first measurement of changes in ozone resulting from SPEs was reported by Weeks et al. (1972). Rockets fired during and after the November 2, 1969, SPE showed a large decrease in ozone even at 52 km, the lowest altitude ob- served. The atmospheric chemistry required to explain such a depletion was developed by Swider and Keneshea (1973) and further revised by Frederick (1976) and Swider et al.