Assessing drought cycles in SPI time series using a Fourier analysis

Elsa E. Moreira, D. S. Martins, L. S. Pereira, DM Group Author

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

In this study, drought in Portugal was assessed using 74 time series of Standardized Precipitation Index (SPI) with a 12 month time scale and 66 years length. A clustering analysis on the SPI Principal Components loadings was performed in order to find regions where SPI drought characteristics are similar. A Fourier analysis was then applied to the SPI time series included in each cluster to investigate the existence of cycles that could represent the return periods of droughts. The most frequent and significant cycles that compound the time series in each of the three clusters were therefore identified and analysed. Results show that droughts periodicities vary among the three clusters identified. The results point to a cycle with 6 years return period of droughts occurrence across the country and a cycle with 9.4 years period of droughts with very high presence in central and southern Portugal. Both these cycles are likely showing influences of the North Atlantic Oscillation on the occurrence and severity of droughts in Portugal.
Original languageEnglish
Pages (from-to)571-585
JournalNatural Hazards And Earth System Sciences
Volume15
Issue number3
DOIs
Publication statusPublished - 15 Mar 2015

Keywords

  • ATLANTIC OSCILLATION INFLUENCE
  • IBERIAN PENINSULA
  • WINTER PRECIPITATION
  • TEMPORAL VARIABILITY
  • HARMONIC-ANALYSIS
  • SPATIAL-PATTERNS
  • MONSOON RAINFALL
  • SOLAR-ACTIVITY
  • WET PERIODS
  • PORTUGAL

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