COMPARISONS OF OBSERVED OZONE TRENDS IN THE STRATOSPHERE THROUGH EXAMINATION OF UMKEHR AND BALLOON OZONESONDE DATA

During the past several years, several authors have published results of the annual and seasonal trends depicted in the total ozone data fro m both satellite and ground-based observations. The examination of the vertical profile data available from the balloon ozonesonde and Umkeh r observations, however, has been generally restricted to limited peri ods and to nonseasonal trend calculations. Within this study, we have examined the nonseasonal and the seasonal trend behavior of the ozone profile data from both ozonesonde and Umkehr measurements in a consist ent manner, covering the same extended time period, 1968-1991, thus pr oviding the first overall comparison of results. Our results reaffirm the observation of significant negative ozone trends in both the lower stratosphere (15-20 km), about -6% per decade, and upper stratosphere (35-50 km), about -6% per decade, separated by a nodal point in the r egion of 25-30 km. The upper stratosphere decrease is, apparently, ass ociated with the classic gas phase chemical effect of the chlorofluoro carbons, whereas the cause of the lower stratospheric decline is still under investigation, but may well be associated with the chlorine and bromine chemistry in this region.