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| Titel |
Multi-decadal river flow variations in France |
| VerfasserIn |
J. Boé, F. Habets |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 18, no. 2 ; Nr. 18, no. 2 (2014-02-19), S.691-708 |
| Datensatznummer |
250120285
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| Publikation (Nr.) |
 copernicus.org/hess-18-691-2014.pdf |
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| Zusammenfassung |
| In this article, multi-decadal variations in the French hydroclimate are
investigated, with a specific focus on river flows. Based on long
observed series, it is shown that river flows in France generally
exhibit large multi-decadal variations in the instrumental period
(defined in this study as the period from the late 19th century to
the present), especially in spring. Differences of means between 21 yr
periods of the 20th century as large as 40% are indeed found
for many gauging stations. Multi-decadal spring river flow variations
are associated with variations in spring precipitation and
temperature. These multi-decadal variations in precipitation are
themselves found to be driven by large-scale atmospheric circulation,
more precisely by a multi-decadal oscillation in a sea level pressure
dipole between western Europe and the eastern Atlantic. It is suggested
that the Atlantic Multidecadal Variability, the main mode of multi-decadal
variability in the North Atlantic–Europe sector, controls those
variations in large-scale circulation and is therefore the main
ultimate driver of multi-decadal variations in spring river
flows. Potential multi-decadal variations in river flows in other seasons, and
in particular summer, are also noted. As they are not associated with
significant surface climate anomalies (i.e. temperature,
precipitation) in summer, other mechanisms are investigated based on
hydrological simulations. The impact of climate variations in spring
on summer soil moisture, and the impact of soil moisture in summer on
the runoff-to-precipitation ratio, could potentially play a role in
multi-decadal summer river flow variations. The large amplitude of
the multi-decadal variations in French river flows suggests that
internal variability may play a very important role in the evolution
of river flows during the next decades, potentially temporarily
limiting, reversing or seriously aggravating the long-term impacts of
anthropogenic climate change. |
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