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| Titel |
Low-frequency variability of European runoff |
| VerfasserIn |
L. Gudmundsson, L. M. Tallaksen, K. Stahl, A. K. Fleig |
| 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 ; 15, no. 9 ; Nr. 15, no. 9 (2011-09-13), S.2853-2869 |
| Datensatznummer |
250012958
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| Publikation (Nr.) |
 copernicus.org/hess-15-2853-2011.pdf |
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| Zusammenfassung |
This study investigates the low-frequency components of observed
monthly river flow from a large number of small catchments in
Europe. The low-frequency components, defined as fluctuations on time
scales longer than one year, were analysed both with respect to their
dominant space-time patterns as well as their contribution to the
variance of monthly runoff.
The analysis of observed streamflow and corresponding time series of
precipitation and temperature, showed that the fraction of
low-frequency variance of runoff is on average larger than, and not
correlated to, the fraction of low-frequency variance of precipitation
and temperature. However, it is correlated with mean climatic
conditions and is on average lowest in catchments with significant
influence of snow. Furthermore, it increases (decreases) under drier
(wetter) conditions – indicating that the average degree of catchment
wetness may be a primary control of low-frequency runoff
dynamics. The fraction of low-frequency variance of runoff is
consistently lower in responsive catchments, with a high
variability of daily runoff.
The dominant space-time patterns of low-frequency runoff in Europe,
identified using nonlinear dimension reduction, revealed that
low-frequency runoff can be described with three modes,
explaining together 80.6% of the variance. The dominant mode has
opposing centres of simultaneous variations in northern and southern
Europe. The secondary mode features a west-east pattern and the third
mode has its centre of influence in central Europe. All modes
are closely related to the space-time patterns extracted from time
series of precipitation and temperature.
In summary, it is shown that the dynamics of low-frequency runoff
follows well known continental-scale atmospheric features, whereas the
proportion of variance attributed to low-frequency fluctuations is
controlled by catchment processes and varies with mean climatic
conditions. The results may have implications for interpreting the
impact of changes in temperature and precipitation on river-flow dynamics. |
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