Statistical analysis of total ozone and stratospheric Umkehr data for trends and solar cycle relationship

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Abstract
We report on trend analysis of Dobson total ozone data through 1984 and stratospheric Umkehr profile ozone data through 1981, including an examination of the relationship between ozone and long‐term solar cycle activity using the 10.7‐cm solar flux data. The estimate of the overall global trend in total ozone during the period 1970–1984, with associated 95% confidence (two standard error) limits, is (−0.26±0.92)% per decade, which indicates no significant overall trend. Based on use of the 10.7‐cm flux measurements, an overall estimate of the total ozone‐solar flux relationship is (1.18±0.66)% change in total ozone from solar cycle minimum to maximum, which indicates a statistically significant positive relationship. Trend analysis of Umkehr data through 1981 yields statistically significant negative trends on the order of (−0.30±0.17)% per year in layers 7 and 8 (∼34–43 km), with Mauna Loa transmission data being used to account for volcanic aerosol effects on the Umkehr data. The analysis also indicates significant relationships between Umkehr data and solar flux in layers 6 and 7 (∼29–38 km) of (2.57±1.25)% and (3.40±2.16)% change, respectively, from solar cycle minimum to maximum, with no significant relationship detected in the higher layers 8 and 9 where the estimates are more variable. Comparison of these empirical estimates with theoretical model calculations is discussed. Trend analysis of Umkehr data using data through 1984 is not reported in this paper because of the severe impact of volcanic aerosols from El Chichon on the Umkehr measurements during 1982–1984, although further research on methods for adjustment of Umkehr data for aerosol effects during this period is continuing.