Ternon Jean-François, Roberts M. J., Morris T., Hancke L., Backeberg B. (2014). In situ measured current structures of the eddy field in the Mozambique Channel. In :
Barlow R. (ed.), Marsac Francis (ed.), Ternon Jean-Francois (ed.), Roberts M. (ed.). The Mozambique channel : mesoscale dynamics and ecosystem responses. Deep-Sea Research Part II.Topical Studies in Oceanography, 100 (No spécial), p. 10-26. ISSN 0967-0645.
Titre du document
In situ measured current structures of the eddy field in the Mozambique Channel
Ternon Jean-François, Roberts M. J., Morris T., Hancke L., Backeberg B.
In
Barlow R. (ed.), Marsac Francis (ed.), Ternon Jean-Francois (ed.), Roberts M. (ed.), The Mozambique channel : mesoscale dynamics and ecosystem responses
Source
Deep-Sea Research Part II.Topical Studies in Oceanography, 2014,
100 (No spécial), p. 10-26 ISSN 0967-0645
Circulation and the related biological production have been studied during five cruises conducted in the Mozambique Channel (MZC) between 2005 and 2010. The circulation in the MZC is known to be highly turbulent, favouring enhanced primary production as a result of mesoscale eddy dynamics, and connectivity throughout the Channel due to the variable currents associated with migrating eddies. This paper presents the results of in situ measurements that characterize the horizontal and vertical currents in the surface and subsurface layers (0-500 m). The in situ data were analysed together with the geostrophic eddy field observed from satellite altimeter measurements. Different circulation regimes were investigated, including the "classical" anticyclonic eddy generated at the Channel narrows (16 S), the enhancement of southward migrating eddies by merging with structures (both cyclonic and anticyclonic) formed in the east of the Channel, and the presence of a fully developed cyclonic eddy at the Channel narrows. Comparison between in situ measurements (S-ADCP and velocities derived from surface drifters) and the geostrophic current derived from sea surface height measurements indicated that the latter can provide a reliable, quantitative description of eddy driven circulation in the MZC, with the exception that these currents are weaker by as much 30%. It is also suggested from in situ observation (drifters) that the departure from geostrophy of the surface circulation might be linked to strong wind conditions. Finally, our observations highlight that a-geostrophic currents need to be considered in future research to facilitate a more comprehensive description of the circulation in this area.
