COMPARISONS OF OBSERVED OZONE TRENDS AND SOLAR EFFECTS IN THE STRATOSPHERE THROUGH EXAMINATION OF GROUND-BASED UMKEHR AND COMBINED SOLAR BACKSCATTERED ULTRAVIOLET (SBUV) AND SBUV-2 SATELLITE DATA

Within the past year, two papers have been published which present upd ated profile ozone trends from the recently revised ground-based Umkeh r record [Miller et al., 1995] and the combined Nimbus 7 solar backsca ttered ultraviolet (SBUV) and NOAA 11 SBUV 2 satellite data record [Ho llandsworth er al, 1995]. In this paper we compare the ozone trends an d responses to the Ii-year solar cycle (represented by the F10.7 cm ra dio flux) derived from these two datasets for the period June 1977 to June 1991 (November 1978 to June 1991 for the satellite data), We cons ider data at northern midlatitudes (30 degrees-50 degrees N) at altitu des between 25 and 45 km derived from these two data sets. In particul ar, we investigate the effects of spatial sampling differences between the data sets on the derived signals. The trends derived from the two independent data sets are nearly identical at all levels except 35 km , where the Umkehr data indicate a somewhat more negative trend, The t rend is approximately zero near 25 km but becomes more negative in the upper stratosphere, reaching nearly -7% per decade in the 40-45 km re gion, The upper stratospheric decreases are consistent with model resu lts and are associated with the gas-phase chemical effect of chloroflu orocarbons CFC's and other ozone-destroying chemicals [World Meteorolo gical Organization, 1995], The ozone correlations in the two data sets with the F10.7 cm solar flux are similar, with near-zero solar-induce d ozone variations in the 25-30 km region and statistically significan t in-phase variations at higher altitudes. Estimates of the solar cycl e in the ozone time series at 40-45 km from a regression model indicat e variations of about 4.5% from solar cycle maximum to minimum. Analys is of the satellite overpass data at the Umkehr station locations show s that the average of the data from the 11 Umkehr stations is a good a pproximation for the 30 degrees-50 degrees N zonal mean.