Interannual variability of the Guinea Dome and its possible link with the Atlantic Meridional Mode
- 311 Downloads
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/.
- Barreiro M, Giannini A, Chang P, Saravanan R (2004) On the role of the South Atlantic atmospheric circulation in tropical Atlantic variability. In Earth’s climate: the ocean-atmosphere interaction. Geophys Monogr Ser 147:143–156Google Scholar
- Breugem WP, Hazeleger W, Haarsma RJ (2006) Multi-model study of tropical Atlantic variability and change. Geophys Res Lett. doi: 10.1029/2006GL027831
- Conkright ME et al (1998) World ocean database 1998 documentation and quality control. Available via DIALOG. http://www.nodc.noaa.gov/OC5/WOA98F/woaf_cd/doc/readme.html of subordinate document. Accessed 23 May 2008
- Masumoto Y, Sasaki H, Kagimoto T, Komori N, Ishida A, Sasai Y, Miyama T, Motoi T, Mitsudera H, Takahashi K, Sakuma H, Yamagata T (2004) A fifty-year eddy-resolving simulation of the world ocean–preliminary outcomes of OFES (OGCM for the earth simulator). J Earth Simul 1:35–56Google Scholar
- Pacanowski RC, Griffies SM (2000) MOM 3.0 manual. Available via DIALOG. http://www.gfdl.gov/~smg/MOM/web/guide_parent/guide_parent.html of subordinate document. Accessed 23 May 2008
- Pradhan Y, Lavender SJ, Hardman-Mountford NJ, Aiken J (2006) Seasonal and inter-annual variability of chlorophyll-a concentration in the Mauritanian upwelling: observation of an anomalous event during 1998–1999. Deep Sea Res Part II Top Stud Oceanogr 53:1548–1559. doi: 10.1016/j.dsr2.2006.05.016 CrossRefGoogle Scholar
- Rossignol M, Meyrueis AM (1964) Campagnes oceanographiques du Gerad-Treca, Cent. Oceanogr. Dakar-Thiaroye, ORSTOM, Dakar, Senegal, p 53Google Scholar
- Stramma L, Huttl S, Schafstall J (2005) Water masses and currents in the upper tropical northeast Atlantic off northwest Africa. J Geophys Res. doi: 10.1029/2005JC002939
- Xie SP (1999) A dynamic ocean-atmosphere model of the tropical Atlantic decadal variability. J Clim 12:64–70Google Scholar
- Xie SP, Carton JA (2004) Tropical Atlantic variability: patterns, mechanisms, and impacts. In Earth’s climate: the ocean-atmosphere interaction. Geophys Monogr Ser 147:121–142Google Scholar