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| Titel |
On the nature of rainfall intermittency as revealed by different metrics and sampling approaches |
| VerfasserIn |
G. Mascaro, R. Deidda, M. Hellies |
| 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 ; 17, no. 1 ; Nr. 17, no. 1 (2013-01-29), S.355-369 |
| Datensatznummer |
250017695
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| Publikation (Nr.) |
 copernicus.org/hess-17-355-2013.pdf |
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| Zusammenfassung |
| A general consensus on the concept of rainfall intermittency has not yet been
reached, and intermittency is often attributed to different aspects of rainfall
variability, including the fragmentation of the rainfall support (i.e., the alternation of wet and dry intervals)
and the strength of intensity fluctuations and bursts. To explore these different aspects,
a systematic analysis of rainfall intermittency properties in the time domain
is presented using high-resolution (1-min) data recorded by a network of 201
tipping-bucket gauges covering the entire island of Sardinia (Italy). Four
techniques, including spectral and scale invariance analysis, and computation
of clustering and intermittency exponents, are applied to quantify the
contribution of the alternation of dry and wet intervals (i.e., the rainfall support fragmentation), and the
fluctuations of intensity amplitudes, to the overall intermittency of the rainfall process. The presence of three ranges of scaling
regimes between 1 min to ~ 45 days is first
demonstrated. In accordance with past studies, these regimes can be
associated with a range dominated by single storms, a regime typical of
frontal systems, and a transition zone. The positions of the breaking points
separating these regimes change with the applied technique, suggesting
that different tools explain different aspects of rainfall variability. Results
indicate that the intermittency properties of rainfall support are fairly
similar across the island, while metrics related to rainfall intensity
fluctuations are characterized by significant spatial variability, implying
that the local climate has a significant effect on the amplitude of
rainfall fluctuations and minimal influence on the process of rainfall
occurrence. In addition, for each analysis tool, evidence is shown of spatial patterns
of the scaling exponents computed in the range of frontal systems.
These patterns resemble the main pluviometric regimes observed on the island
and, thus, can be associated with the corresponding synoptic circulation
patterns. Last but not least, we demonstrate how the methodology adopted
to sample the rainfall signal from the records of the tipping instants can
significantly affect the intermittency analysis, especially at smaller
scales. The multifractal scale invariance analysis is the only tool that is
insensitive to the sampling approach. Results of this work may be useful to
improve the calibration of stochastic algorithms used to downscale coarse
rainfall predictions of climate and weather forecasting models, as well as
the parameterization of intensity-duration-frequency curves, adopted for land
planning and design of civil infrastructures. |
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