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| Titel |
Lacunarity, predictability and predictive instability of the daily pluviometric regime in the Iberian Peninsula |
| VerfasserIn |
M. D. Martínez, X. Lana, A. Burgueño, C. Serra |
| 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 ; 14, no. 2 ; Nr. 14, no. 2 (2007-03-14), S.109-121 |
| Datensatznummer |
250012156
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| Publikation (Nr.) |
 copernicus.org/npg-14-109-2007.pdf |
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| Zusammenfassung |
| The complexity of the daily pluviometric regime of the Iberian Peninsula is
analysed from the point of view of its lacunarity, predictability and
predictive instability. The database consists of daily pluviometric records
obtained from 43 rain gauges in Spain and Portugal for the period 1950–1990.
Five different series are generated for every rain gauge. The first series
is constituted by the consecutive daily amounts. The other four consist of
dry spell lengths with respect to daily amount thresholds of 0.1, 1.0, 5.0
and 10.0 mm/day. A dry spell length is defined as the number of consecutive
days with rainfall amounts below one of these thresholds. The empirical
lacunarity for every rain gauge is well reproduced by two power laws, the
exponents varying notably from one gauge to another. The spatial
distribution of the lacunarity is characterised by a north to south or
southeast gradient, thus suggesting that this parameter can be a useful tool
to distinguish between different pluviometric regimes. The predictability of
the five series is quantified by means of the rescaled analysis and the
interpretation of the Hurst exponent. Its patterns reveal that most part of
the Iberian Peninsula shows signs of persistence for the daily rainfall and
the dry spell series, although persistence is only clearly manifested in
some small domains. The instability of possible predictive algorithms is
analysed through the Lyapunov exponents. They are only computed for the
series of daily amounts and for dry lengths respect to the threshold level
of 0.1 mm/day due to the short number of dry spells for larger threshold
levels. The series of daily amounts depict the highest instability along the
Mediterranean coast. The series of dry spells show an increasing instability
from NE to SW Spain, with a relevant nucleus of high Lyapunov values in the
south-western Atlantic coast. As a summary, lacunarity and Hurst and
Lyapunov exponents depict a relevant spatial variation, which is in
agreement with well known patterns of the pluviometric regime, such as
annual amount spatial distribution and return periods of dry spells. |
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