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| Titel |
Tracing the second stage of ozone recovery in the Antarctic ozone-hole with a "big data" approach to multivariate regressions |
| VerfasserIn |
A. T. J. de Laat, R. J. van der A, M. van Weele |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 1 ; Nr. 15, no. 1 (2015-01-08), S.79-97 |
| Datensatznummer |
250119287
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| Publikation (Nr.) |
 copernicus.org/acp-15-79-2015.pdf |
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| Zusammenfassung |
This study presents a sensitivity analysis of multivariate regressions of
recent springtime Antarctic vortex ozone trends using a "big data"
ensemble approach.
Our results indicate that the poleward heat flux (Eliassen–Palm flux) and
the effective chlorine loading respectively explain most of the short-term
and long-term variability in different Antarctic springtime total ozone
records. The inclusion in the regression of stratospheric volcanic aerosols,
solar variability and the quasi-biennial oscillation is shown to increase
rather than decrease the overall uncertainty in the attribution of
Antarctic springtime ozone because of large uncertainties in their
respective records.
Calculating the trend significance for the ozone record from the late 1990s
onwards solely based on the fit of the effective chlorine loading is not
recommended, as this does not take fit residuals into account, resulting in
too narrow uncertainty intervals, while the fixed temporal change of the
effective chlorine loading does not allow for any flexibility in the trends.
When taking fit residuals into account in a piecewise linear trend fit, we
find that approximately 30–60% of the regressions in the full ensemble
result in a statistically significant positive springtime ozone trend over
Antarctica from the late 1990s onwards. Analysis of choices and
uncertainties in time series show that, depending on choices in time series
and parameters, the fraction of statistically significant trends in parts of
the ensemble can range from negligible to a complete 100% significance. We also find
that, consistent with expectations, the number of statistically significant
trends increases with increasing record length.
Although our results indicate that the use multivariate regressions is a
valid approach for assessing the state of Antarctic ozone hole recovery, and
it can be expected that results will move towards more confidence in recovery with increasing record length, uncertainties in choices currently do not yet
support formal identification of recovery of the Antarctic ozone hole. |
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