%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Illig, Serena
%A Bachelery, M. L.
%T Propagation of subseasonal equatorially-forced coastal trapped waves down to the Benguela upwelling system
%D 2019
%L fdi:010075550
%G ENG
%J Scientific Reports - Nature
%@ 2045-2322
%K ATLANTIQUE
%K BENGUELA COURANT
%M ISI:000462585600016
%P art. 5306 [10 ]
%R 10.1038/s41598-019-41847-1
%U https://www.documentation.ird.fr/hor/fdi:010075550
%> https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers19-04/010075550.pdf
%V 9
%W Horizon (IRD)
%X The oceanic connection between the coastal variability along the southwestern African coasts and the linear equatorial dynamics at subseasonal time-scales (<120 days) is examined using a variety of model outputs, ranging from linear to general circulation models. We focus on the equatorially-forced fast and weakly dissipative first-mode coastal trapped waves which are shown to propagate down to the southern tip of Africa. In the eastern equatorial Atlantic, the first-mode equatorial forcing is tangled with the higher-order Kelvin wave modes and is overshadowed by the dominant second baroclinic mode. The latter is slower and peaks 10 days after the concealed first-mode contribution. Within this time frame, the remotely-forced first-mode coastal trapped waves impinge on the variability of the Benguela upwelling ecosystem, almost in phase with the subseasonal sea level fluctuations in the Gulf of Guinea. Over 1993-2008, the equatorial forcing undergoes a substantial interannual modulation. Periods of energetic first-mode equatorial Kelvin waves coincide with a strong subseasonal coastal wind activity that breaks the stronger equatorial connection. This suggests the existence of a large-scale atmospheric connection between the equatorial wave forcing and the along-shore winds in the Benguela, modulating the maximum latitude at which the equatorial dynamics impacts the local marine resources.
%$ 032