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- Title
Eddy‐Driven Cross‐Shelf Transport in the East Australian Current Separation Zone.
- Authors
Malan, Neil; Archer, Matthew; Roughan, Moninya; Cetina‐Heredia, Paulina; Hemming, Michael; Rocha, Carlos; Schaeffer, Amandine; Suthers, Iain; Queiroz, Eduardo
- Abstract
In western boundary current systems, sharp velocity gradients between the poleward flowing jet and coastal waters generally act to inhibit cross‐shelf exchange. Downstream of jet separation, dynamic mesoscale eddies dominate the flow. In the East Australian Current System, counter‐rotating eddy dipoles are often present which, in the appropriate configuration, have potential to drive cross‐shelf transport. However, this eddy dipole mode is poorly understood in the framework of cross‐shelf exchange and the effect of these structures on shelf waters is uncertain. Using 25 years of satellite altimetry, as well as in situ sampling of a typical dipole event, we investigate the characteristics of eddy‐driven cross‐shelf exchange. We show that the maximum onshore velocity is driven by an eddy dipole structure and occurs in a defined latitudinal band between 33°S and 34°S more than 50% of the time. We sample a typical eddy dipole and find a strong onshore jet, 37 km wide, with velocities up to 1.78 m s −1 and a transport of at least 16 Sv. Hydrographic data from an autonomous underwater glider show that this jet manifests on the shelf as a subsurface intrusion of warm salty water extending from offshore up onto the midshelf. In the light of climatic changes in western boundary current transport and the increase in their eddy kinetic energy, understanding eddy‐driven cross‐shelf exchange is important to predict future changes to the shelf water mass. Key Points: An eddy dipole mode is the main driver of cross‐shelf transport in the East Australian Current extensionDipole events can result in onshore velocities up to 1.78 m s −1, with a maximum transport at 33–34°SWater from the observed dipole jet is advected from offshore up to the midshelf in the form of a warm salty intrusion of offshore water
- Subjects
EAST Australian Current; EQUATORIAL currents; SALINITY; UNDERWATER gliders; GEOSTROPHIC currents
- Publication
Journal of Geophysical Research. Oceans, 2020, Vol 125, Issue 2, p1
- ISSN
2169-9275
- Publication type
Article
- DOI
10.1029/2019JC015613