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East Australian Current (the EAC)
Where is it?
EAC Properties• Warm, deep, fast, nutrient
poor water• 100 km wide by 500km deep• 30 million m3/s transport! • Well known for eddy
formation (can be 200km across!)
Physical Description• Balance of Ekman wind-stress and coastal
friction (balance of wind curl and frictional vorticity)
• In S.H. : curl + or counterclockwise and friction vorticity – or clockwise
• Stommel- Coriolis term varies with latitude, strengthens W. Boundary EAC
• Surface EAC also strengthened (some) by deep->shallow shelf
Wind field response drives separation (not New Zealand or bottom topography
Eddies• Geostrophic balance: pressure balances coriolis• Cyclonic clockwise around low-pressure cells and counterclockwise (anticyclonic around high pressure cells) IN S.Hemis!
UpwellingW. coast of Aus doesn’t have wind-
driven upwellingInstead EAC “encroachment”
towards coast pushes up isopycnals
References
M. Roughan, J.H. Middleton / Continental Shelf Research 22 (2002) 2551–2572K.R. Ridgway, J.R. Dunn / Progress in Oceanography 56 (2003) 189-222http://www.cmar.csiro.au/remotesensing/oceancurrents/http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=15366
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