Stable Oxygen Isotopic Composition of Corals from the Gulf of Guinea as Indicators of Periods of Extreme Precipitation Conditions in the Sub-Sahara

Authors

Peter Koenraad Swart, University of Miami
Kathy S. White, University of Miami
David Enfield, National Oceanic and Atmospheric Association
Richard E. Dodge, Nova Southeastern UniversityFollow
Peter Milne, University of Miami

Document Type

Article

Publication Title

Journal of Geophysical Research

ISSN

0148-0227

Publication Date

11-15-1998

Keywords

Radioactivity, Radioisotopes

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.

DOI

10.1029/98JC02404

Volume

103

Issue

12

First Page

27885

Last Page

27891

Comments

©1998 by the American Geophysical Union

NSUWorks Citation

Swart, Peter K., Kathy S. White, David Enfield, Richard E. Dodge, and Peter Milne. "Stable oxygen isotopic composition of corals from the Gulf of Guinea as indicators of periods of extreme precipitation conditions in the sub‐Sahara." Journal of Geophysical Research: Oceans (1978–2012) 103, no. C12 (1998): 27885-27891.