Analysis of the 1984--1996 SAGE II ozone mixing ratio data revealed that the occurrence of minima was strongly stratified in altitude, both globally and seasonally, when analyzed against the curvature of minima. Four dominant stratified regions of ozone mixing ratio minima were found to exist in the 20--45 km altitude range, and studies of their frequency of occurrence, altitude distribution, vertical extent, depth of ozone reduction, and minima profiles are included. Dominant minima near 30 km were found to be more frequent closer to the subtropics during the winter, and they displayed a semiannual variation in frequency and depth in the tropics. Time variation in the mean depth of minima near 30 km did not reveal significant change over the period 1979--1996. Significant positive departures in the ozone mixing ratio were found to occur immediately above and below minima, and the difference between these upper and the lower departures was observed to depend on the vertical distance of minima from the mean altitudes of stratification. A comparison between minima analyses of SAGE and ozonesonde profiles from the South Australian region, for the two periods December--March and May--August, indicated consistency in the vertical distribution, in the minima depths, and in the positive departures in mixing ratio above and below the altitude of the minima. ¿ 2000 American Geophysical Union