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Salinity dominance on the Indian Ocean Eastern Gyral current
Author(s) -
Menezes Viviane V.,
Phillips Helen E.,
Schiller Andreas,
Domingues Catia M.,
Bindoff Nathaniel L.
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2013gl057887
Subject(s) - sverdrup , throughflow , salinity , geostrophic current , geostrophic wind , oceanography , argo , current (fluid) , geology , water mass , subtropical front , ocean current , temperature salinity diagrams , ekman transport , boundary current , ocean surface topography , climatology , upwelling , arctic , soil science
This study demonstrates the importance of salinity gradients to the formation of the Eastern Gyral Current (EGC) in the South Indian Ocean. The EGC flows eastward near 15 ∘ S, opposite to the direction predicted by classical theories of wind‐driven circulation and is a source of water for the Leeuwin Current. In the upper ocean, a strong salinity front exists between fresh water from the Indonesian Throughflow (ITF) in the South Equatorial Current (SEC) and salty subtropical waters. In that region, salinity overwhelms the temperature contribution to density gradients, generating eastward geostrophic shear and establishing the EGC. Without the salinity front the EGC cannot be maintained: If the salinity contribution is neglected in the calculation of geostrophic currents, the EGC vanishes. Our observational analysis associated with the fact that both Sverdrup and Ekman theories produce westward flows in the region strongly supports the idea that the EGC is a salinity‐driven current.