COMPARISON OF SEASONAL-VARIATIONS OF UPPER STRATOSPHERIC OZONE CONCENTRATIONS REVEALED BY UMKEHR AND NIMBUS-4-BUV OBSERVATIONS

The results are reported of a comparison between upper stratospheric ozone concentration profiles in the region between 22 and 1. 4 mbar, as determined from surface-based Umkehr observations and satellite Nimbus 4 BUV observations. Aside from some bias in the magnitudes of the Umkehr and BUV data, marked annual cycles of ozone concentration in the upper stratosphere are clearly revealed. Above 4 mbar the profiles show a summer minimum and a winter maximum, while below 4 mbar the annual variation is reversed from this pattern. In the northern hemisphere the winter maximum is accompanied by a secondary minimum of 1- to 2-month duration near 3 mbar. This short-term minimum is much less obvious in the southern hemisphere data. Some of the problems of attempting to monitor long-term changes in the upper stratosphere are discussed briefly.