Causes and Effects of Stratospheric Ozone Reduction An Update (1982) / Chapter Skim
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E TREND ANALYSIS OF TOTAL OZONE
E TREND ANALYSIS OF TOTAL OZONE
Pages 306-314
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From page 306... ...
reveals considerable differences in long-term variations from region to region; but, on the average, trends appear to be mostly positive in the 1960s and near zero in the 1970s. As we will see, more recent analyses based on sophisticated statistical models suggest positive trends in the 1970s, which are, however, not significantly different from zero.
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The main disagreement remaining concerns the extent to which statistical analysis can be used as an early warning system for the future. For the Dobson network, there are two main problems: first, how representative is the Dobson network of the global ozone distribution?
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STATISTICAL ANALYSIS OF THE DOBSON NETWORK Three separate groups of statisticians (Bloomfield et ale 1981, Reinsel et al.
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However, it should be noted that these three sets of differences cannot be associated with physical causes on a one-to-one basis. For example, "random" errors are introduced in the monthly averages by missing data, by the effect of large variations with periods of the order of a week, by local air pollution episodes or clouds, or simply by observational error.
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They found no statistically significant differences in this one small sample covering only a few years. The authors concluded from this result that there are no differences between global trends and trends derived from Dobson station data.
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do not differ LOW-FREQUENCY VARIATIONS Bishop and Hill (1981) used a partially inhomogeneous Arosa record to estimate the trend uncertainty due to low-frequency variations (not directly analyzable with the record of the Dobson network)
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SUMMARY AND RECOMMENDATIONS Because of the various controversies, it is not possible to arrive at a definite understanding of the uncertainties of global decadal ozone trends derived from Dobson stations or satellites. The statisticians using the "hockey stick" models would estimate the standard deviations of the decadal trends derived from Dobson stations to be of the order of 1 percent.
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Pages 337-339, Proceedings of the Quadrennial International Ozone Symposium, August 4-9, 1980. Boulder, Colo.: National Center for Atmospheric Research.
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Nytchka (1981) Statistical analysis of stratospheric ozone data for detection of trend.
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