Two years of Nimbus 4 backscattered ultraviolet data have been recalibrated and reprocessed. A Laplace transform inversion was applied to radiances at 2876 ¿ and below for 560,000 individual scans for the period April 1970--May 1972. The behavior of ozone near 50 km as a function of time, latitude, and longitude is presented. The high-latitude 1-mbar ozone mixing ratio is maximum at the winter solstice, about 10 μg/g, and is minimum at the summer solstice, about 4 μg/g. Below 30¿ latitude the ozone is fairly constant at 4μg/g. Ozone variability is large in winter and spring and small in summer and fall.