Hobart

Seminar Abstract

Friday 24 October 2008, 11.30am (Tas time)
CSIRO Auditorium, Hobart

Lisa M Beal
The Rosenstiel School of Marine and Atmospheric Science
The Division of Meteorology and Physical Oceanography
University of Miami

Mixing and interleaving characteristics of the Agulhas Current

Observations at four principal latitudes in the Agulhas Current show that the water mass properties on either side of its dynamical core are significantly different. Three lateral mixing regimes for the Agulhas Current are suggested. The surface and thermocline waters are always inhibited from mixing by the presence of both a strong, cross-frontal potential vorticity gradient and kinematic steering. At intermediate depths mixing is inhibited by steering alone, and hence driven by periodic meander events. Finally, in the deep waters there is a regime of free lateral mixing. Cross-frontal interleaving of these distinct water masses is observed at over 80% of the stations occupied in the Agulhas Current. Direct velocity measurements allow for a comparison between the characteristic vertical length scales of the Agulhas intrusions and those of velocity perturbations found throughout the current. It is found that the interleaving scales match those of the velocity perturbations, which are identified as near-inertial oscillations. Furthermore, the properties of the intrusions indicate that double diffusion is not an important process in their development. It is suggested that Agulhas intrusions are the result of the interaction of mesoscale stirring and vertical mixing by near- inertial oscillations.

[back]

Location:
CSIRO = Marine Laboratories Auditorium, Castray Esplanade, Hobart

For further information, or to schedule a seminar, contact:
To schedule a seminar, contact:
Bernadette Sloyan, (Oceanographic seminars) CSIRO Marine and Atmospheric Research (03) 6232 5152
Thomas Kunz, (Biological seminars) CSIRO Marine and Atmospheric Research
(03) 6232 5076
Natalie Dowling, (Fisheries Modelling) CSIRO Marine and Atmospheric Research
(03) 6232 5148
Jillian Enraght-Moony, (seminar administrator) CSIRO Marine and Atmospheric Research (03) 6232 5320
Communications Manager, Antarctic Climate and Ecosystems CRC (03) 6226 2265
Margaret Hazelwood, Institute of Antarctic and Southern Ocean Studies (IASOS) University of Tasmania (03) 6226 2971

Last updated 21/07/09