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| Titel |
Climate trends and behaviour of drought indices based on precipitation and evapotranspiration in Portugal |
| VerfasserIn |
A. A. Paulo, R. D. Rosa, L. S. Pereira |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 12, no. 5 ; Nr. 12, no. 5 (2012-05-16), S.1481-1491 |
| Datensatznummer |
250010815
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| Publikation (Nr.) |
 copernicus.org/nhess-12-1481-2012.pdf |
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| Zusammenfassung |
| Distinction between drought and aridity is crucial to understand water
scarcity processes. Drought indices are used for drought identification and
drought severity characterisation. The Standardised Precipitation Index
(SPI) and the Palmer Drought Severity Index (PDSI) are the most known
drought indices. In this study, they are compared with the modified PDSI for
Mediterranean conditions (MedPDSI) and the Standardised Precipitation
Evapotranspiration Index (SPEI). MedPDSI results from the soil water balance
of an olive crop, thus real evapotranspiration is considered, while SPEI
uses potential (climatic) evapotranspiration. Similarly to the SPI, SPEI can
be computed at various time scales. Aiming at understanding possible impacts
of climate change, prior to compare the drought indices, a trend analysis
relative to precipitation and temperature in 27 weather stations of Portugal
was performed for the period 1941 to 2006. A trend for temperature increase
was observed for some weather stations and trends for decreasing
precipitation in March and increasing in October were also observed for some
locations. Comparisons of the SPI and
SPEI at 9- and 12-month time scales, the PDSI and MedPDSI
were performed for the same stations and period. SPI
and SPEI produce similar results for the same time scales concerning drought
occurrence and severity. PDSI and MedPDSI correlate well between them and
the same happened for SPI and SPEI. PDSI and MedPDSI identify more severe
droughts than SPI or SPEI and identify drought occurrence earlier than these
indices. This behaviour is likely to be related with the fact that a water
balance is performed with PDSI and MedPDSI, which better approaches the
supply-demand balance. |
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