Stable oxygen isotopic composition of corals from the Gulf of Guinea as indicators of periods of extreme precipitation conditions in the sub-Sahara

Peter K Swart, K. S. White, D. Enfield, R. E. Dodge, P. Milne

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Stable oxygen isotopic analyses of scleractinian coral skeletons from the Gulf of Guinea in the eastern Atlantic reveal that the corals from this region can be used to identify periods of severe drought and above average precipitation in sub-Sahara Africa. Data presented in this paper show an inverse correlation between precipitation in the Sahel and the δ18O values of a coral skeletons of the species Siderastrea spp. collected from the island of Principe in the Gulf of Guinea. This is opposite to the correlation expected, as previous work has suggested that higher sea surface temperatures occur in the Gulf of Guinea during periods of low rainfall in the Sahel. Such an association would lead to a positive correlation between Sahel precipitation and skeletal δ18O. The explanation for the observed inverse correlation is that the salinity of the Gulf of Guinea is strongly influenced by the outflow from the Niger and Congo rivers. These periods of high freshwater input also correlate with periods of higher rainfall in the sub-Sahara and therefore affect the δ18O values of the coral skeleton. The correlation between δ18O values of the coral skeleton and temperature in the northern subtropical Atlantic Ocean (r= -0.34), the magnitude of the dipole (r= -0.45), and the latitudinal position of the intertropical convergence zone (r= -0.37) illustrate that the δ18O values in the coral skeleton reflect climate dynamics of the region that affect the precipitation patterns in sub-Sahara Africa.

Original languageEnglish (US)
JournalJournal of Geophysical Research C: Oceans
Volume103
Issue numberC12
StatePublished - Nov 15 1998

Fingerprint

Guinea
gulfs
musculoskeletal system
Rain
coral
isotopic composition
skeleton
Oxygen
oxygen
Drought
Precipitation (meteorology)
Chemical analysis
Rivers
Association reactions
Temperature
Niger
drought
Atlantic Ocean
sea surface temperature
salinity

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science
  • Astronomy and Astrophysics
  • Oceanography

Cite this

Stable oxygen isotopic composition of corals from the Gulf of Guinea as indicators of periods of extreme precipitation conditions in the sub-Sahara. / Swart, Peter K; White, K. S.; Enfield, D.; Dodge, R. E.; Milne, P.

In: Journal of Geophysical Research C: Oceans, Vol. 103, No. C12, 15.11.1998.

Research output: Contribution to journalArticle

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