Skip navigation
Please use this identifier to cite or link to this item:

Full metadata record
DC FieldValueLanguage
dc.contributor.authorSantos, João Filipe-
dc.contributor.authorPulido-Calvo, Inmaculada-
dc.contributor.authorPortela, Maria Manuela-
dc.identifier.citationJournal of Water Resources Research, 46, ISSN 0043–1397.por
dc.description.abstractAn analysis of droughts in Mainland Portugal based on monthly precipitation data, from September 1910 to October 2004, in 144 rain gages distributed uniformly over the country is presented. The drought events were characterized by means of the Standardized Precipitation Index (SPI) applied to different time scales (1, 6 and 12 consecutive months and 6 months from April to September and 12 months from October to September). To assess spatial and temporal patterns of droughts, a principal component analysis (PCA) and K means clustering (KMC) were applied to the SPI series. By this way three different and spatially well-defined regions with different temporal evolution of droughts were identified (north, central and south regions of Portugal). A spectral analysis of the SPI patterns obtained with principal component analysis and clusters analysis, using the fast Fourier transform algorithm (FFT), showed that there is a manifest 3.6-years cycle in the SPI pattern in the south of Portugal and evident 2.4-year and 13.4-year cycles in the north of Portugal. The observation of the drought periods supports the occurrence of more frequent cycles of dry events in the south (droughts from moderate to extreme approximately every 3.6 years) than in the north (droughts from severe to extreme approximately every 13.4 years). These results suggest a much stronger immediate influence of the NAO in the south than in the north of Portugal, although these relations remain a challenging task.por
dc.publisherAmerican Geophysical Unionpor
dc.subjectStandardized Precipitation Index (SPI)por
dc.subjectPrincipal component analysis (PCA)por
dc.subjectClusters analysispor
dc.subjectFast fourier transform (FFT)por
dc.titleSpatial and temporal variability of droughts in Portugalpor
Appears in Collections:D-ENG - Artigos em revistas com peer review

Files in This Item:
File Description SizeFormat 
Journal_WRR_AGU_Santos_Portela_Calvo_2010(en).pdf648.77 kBAdobe PDFView/Open

FacebookTwitterDeliciousLinkedInDiggGoogle BookmarksMySpace
Formato BibTex MendeleyEndnote Currículo DeGóis 

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.