Interannual variability of the Guinea Dome and its possible link with the Atlantic Meridional Mode
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Using a high-resolution ocean general circulation model forced by NCEP/NCAR reanalysis data, the interannual variability of the Guinea Dome is studied from a new viewpoint of its possible link with the Atlantic Meridional Mode (AMM), which is related to the meridional migration of the Intertropical Convergence Zone (ITCZ). The dome develops off Dakar seasonally from late spring to late fall owing to the wind-induced Ekman upwelling; its seasonal evolution is associated with the northward migration of the ITCZ. When the ITCZ is located anomalously northward (southward) from late spring to early summer, as a result of the wind-evaporation-sea surface temperature (SST) positive feedback with positive (negative) SST anomaly over the Northern Hemisphere, the dome becomes unusually strong (weak) in fall as a result of stronger (weaker) Ekman upwelling. This may contribute to the decay of the AMM. Thus, the coupled nature between the AMM and the Guinea Dome could be important in understanding, modeling, and predicting the tropical Atlantic variability.
KeywordsAtlantic Meridional Mode Guinea Dome Intertropical Convergence Zone Interannual variability
We thank H. Sasaki and Y. Masumoto for the OFES data, which was run on the Earth Simulator Center of Japan Agency for Marine-Earth Science and Technology. The present research is supported by the Japan Society for Promotion of Science (JSPS) through Grant-in-Aid for Scientific Research B (20340125). Also, the first author is supported by the Research Fellowship of the JSPS for Young Scientists (208479). Wavelet software was provided by C. Torrence and G. Compo, and is available at http://atoc.colorado.edu/research/wavelets/.
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