Low-frequency variability and zonal contrast in Sahel rainfall and Atlantic sea surface temperature teleconnections during the last century

Bastien Dieppois, Alain Durand, Matthieu Fournier, Arona Diedhiou, Bernard Fontaine, Nicolas Massei, Zeinnedine Nouaceur, David Sebag

Research output: Contribution to journalArticle

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Abstract

This study systematically examines teleconnections between Atlantic sea surface temperature (SST) and the west–east distribution of Sahel rainfall throughout the twentieth century, taking nonstationarity into account. Sahel rainfall variability of six selected rain gauges displays three dominant time scales: multi-decadal (>20 years), quasi-decadal (8–18 years) and interannual (2–8 years). Regarding their patterns of low-frequency scales, three coherent Sahelian subregions can be identified: the Atlantic Coast (Dakar), western–central Sahel (Nioro and Mopti) and eastern Sahel (Niamey, Maradi, Maine-Soroa). Cross-analyses combining spectral and multivariate analyses of 20 station-based data and West-African gridded rainfall data statistically confirm dissimilarities between the western and eastern Sahel. Western and eastern Sahel rainfall data are correlated with SSTs from different regions of the Atlantic Ocean, especially in the North and tropical South Atlantic. As determined by wavelet coherence and phase, in-phase relationship with North Atlantic SSTs only occurs in wet periods and at the multi- and quasi-decadal scales. This teleconnection depends on the time period and the time scale, displaying a NW–SE pattern, which suggests nonuniform modulations of meridional displacements of the Intertropical Convergence Zone (ITCZ). Tropical South Atlantic SST variability is often related to opposite patterns between the Gulf of Guinean Coast (in phase) and Sahel region (out of phase).
Original languageEnglish
Pages (from-to)139-155
Number of pages7
JournalTheoretical and Applied Climatology
Volume121
Issue number1
Early online date23 Jul 2014
DOIs
Publication statusPublished - Jul 2015

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teleconnection
sea surface temperature
rainfall
timescale
coast
intertropical convergence zone
twentieth century
wavelet
gauge
ocean

Keywords

  • Sahel rainfall
  • Atlantic sea surface temperature

Cite this

Low-frequency variability and zonal contrast in Sahel rainfall and Atlantic sea surface temperature teleconnections during the last century. / Dieppois, Bastien; Durand, Alain; Fournier, Matthieu; Diedhiou, Arona; Fontaine, Bernard; Massei, Nicolas; Nouaceur, Zeinnedine; Sebag, David .

In: Theoretical and Applied Climatology, Vol. 121, No. 1, 07.2015, p. 139-155.

Research output: Contribution to journalArticle

Dieppois, Bastien ; Durand, Alain ; Fournier, Matthieu ; Diedhiou, Arona ; Fontaine, Bernard ; Massei, Nicolas ; Nouaceur, Zeinnedine ; Sebag, David . / Low-frequency variability and zonal contrast in Sahel rainfall and Atlantic sea surface temperature teleconnections during the last century. In: Theoretical and Applied Climatology. 2015 ; Vol. 121, No. 1. pp. 139-155.
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