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| Titel |
The influence of the North Atlantic Oscillation and El Niño–Southern Oscillation on mean and extreme values of column ozone over the United States |
| VerfasserIn |
I. Petropavlovskikh, R. Evans, G. McConville, G. L. Manney, H. E. Rieder |
| 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. 3 ; Nr. 15, no. 3 (2015-02-13), S.1585-1598 |
| Datensatznummer |
250119410
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| Publikation (Nr.) |
 copernicus.org/acp-15-1585-2015.pdf |
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| Zusammenfassung |
| Continuous measurements of total ozone (by Dobson spectrophotometers) across
the contiguous United States began in the early 1960s. Here, we analyze
temporal and spatial variability and trends in total ozone from the five US
sites with long-term records. While similar long-term ozone changes are
detected at all five sites, we find differences in the patterns of ozone
variability on shorter timescales. In addition to standard evaluation
techniques, STL-decomposition methods (Seasonal Trend decomposition of time
series based on LOESS (LOcally wEighted Scatterplot Smoothing)) are used to
address temporal variability and "fingerprints" of dynamical features in the
Dobson data. Methods from statistical extreme value theory (EVT) are used to
characterize days with high and low total ozone (termed EHOs and ELOs,
respectively) at each station and to analyze temporal changes in the
frequency of ozone extremes and their relationship to dynamical features
such as the North Atlantic Oscillation (NAO) and El Niño–Southern Oscillation.
A comparison of the fingerprints detected in the frequency distribution of
the extremes with those for standard metrics (i.e., the mean) shows that
more fingerprints are found for the extremes, particularly for the
positive phase of the NAO, at all five US monitoring sites. Results from the
STL decomposition support the findings of the EVT analysis. Finally, we
analyze the relative influence of low- and high-ozone events on seasonal mean
column ozone at each station. The results show that the influence of ELOs
and EHOs on seasonal mean column ozone can be as much as ±5 %,
about as large as the overall long-term decadal ozone trends. |
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