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| Titel |
Evolution of atmospheric connectivity in the 20th century |
| VerfasserIn |
F. Arizmendi, A. C. Martí, M. Barreiro |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 21, no. 4 ; Nr. 21, no. 4 (2014-08-08), S.825-839 |
| Datensatznummer |
250120932
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| Publikation (Nr.) |
 copernicus.org/npg-21-825-2014.pdf |
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| Zusammenfassung |
We aim to study the evolution of
the upper atmosphere connectivity over the 20th century as well as to
distinguish the oceanically forced component from the atmospheric internal
variability. For this purpose we build networks from two different reanalysis
data sets using both linear and nonlinear statistical similarity measures to
determine the existence of links between different regions of the world in
the two halves of the last century. We furthermore use symbolic analysis to
emphasize intra-seasonal, intra-annual and inter-annual timescales. Both
linear and nonlinear networks have similar structures and evolution, showing
that the most connected regions are in the tropics over the Pacific Ocean.
Also, the Southern Hemisphere extratropics have more connectivity in the
first half of the 20th century, particularly on intra-annual and
intra-seasonal timescales.
Changes over the Pacific main connectivity regions are analyzed in more
detail. Both linear and nonlinear networks show that the central and western
Pacific regions have decreasing connectivity from early 1900 up to about
1940, when it starts increasing again until the present. The inter-annual
network shows a similar behavior. However, this is not true of other
timescales. On intra-annual timescales the minimum connectivity is around
1956, with a negative (positive) trend before (after) that date for both the
central and western Pacific. While this is also true of the central Pacific
on intra-seasonal timescales, the western Pacific shows a positive trend
during the entire 20th century.
In order to separate the internal and forced connectivity networks and to
study their evolution through time, an ensemble of atmospheric general
circulation model outputs is used. The results suggest that the main
connectivity patterns captured in the reanalysis networks are due to the
oceanically forced component, particularly on inter-annual timescales.
Moreover, the atmospheric internal variability seems to play an important
role in determining the intra-seasonal timescale networks. |
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