Data/hora: 06/06/2024 02:34:39

Provedor de dados: | 5
País: | France
Título: | Modélisation haute-résolution des courants dans le Golfe de Guinée : Etude des oscillations bimensuelles.
Autores: | Guiavarch, Catherine.
Data: | 2007-03-12
Ano: | 2007
Palavras-chave: | Deep current; Biweekly oscillations; Equatorial waves; Coastal trapped waves; Gulf of Guinea; Numerical modelling; Courant profond; Oscillations bimensuelles; Ondes équatoriales; Ondes piégées à la côte; Golfe de Guinée; Modélisation numérique.
Resumo: | Currentmeter measurements on the continental slope of the Gulf of Guinea (near 7°40 S) point out a biweekly oscillation of the currents, bottom intensified and oriented along the bathymetry. Those energetic oscillations dominate the signal. A three-dimensional high-resolution primitive equation model  (NEMO/OPA) of the Gulf of Guinea has been developed to study the oscillations and their forcing mechanism.  The data does not support the tide as a forcing mechanism and the wind-forced regional model reproduces biweekly oscillations, which fit the data quite well. Experiments with different forcings have been run to explore the origin of the biweekly variability. Those experiments highlight the equatorial origin of the oscillations forced by equatorial winds. At the equator, wind-forced Yanaï waves propagate eastward, reach the coast and propagate poleward in both directions. The dominant period of 15-day can be explained by equatorial waves theory. In the equatorial Atlantic, there are no 15-day waves propagating westward, thereby all the incident energy reaching the African coast propagates poleward via coastal-trapped waves. The spatial structure and the temporal variability of the biweekly waves are examined using the regional model and a linear mode of the equatorial Atlantic. High baroclinic modes explain the bottom intensification and the decrease of the signal to the South, because of the fast dissipation of the highest modes.   Intermittency of the biweekly signal is underlined by wavelet analysis of the data and partially reproduced by the regional model but not by the linear model. Although being forced by equatorial winds, the temporal variability of the oscillations is not directly correlated with the variability of the equatorial winds.
Tipo: | Text
Idioma: | Francês
Identificador: | http://archimer.ifremer.fr/doc/2007/these-3647.pdf
Editor: | Université de Bretagne Occidentale
Relação: | http://archimer.ifremer.fr/doc/00000/3647/
Formato: | application/pdf