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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110, C03019, doi:10.1029/2004JC002533, 2005

Variability and forcing of the East Australian Current

Melissa M. Bowen

Colorado Center for Astrodynamics Research, University of Colorado, Boulder, Colorado, USA


John L. Wilkin

Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, New Jersey, USA


William J. Emery

Colorado Center for Astrodynamics Research, University of Colorado, Boulder, Colorado, USA


Abstract

The spatial and temporal variability of the East Australian Current (EAC) is investigated using 6 years (1993–1998) of surface geostrophic stream function from an optimal interpolation of altimeter sea surface heights and velocities derived from tracking thermal features in satellite imagery. Variability appears as a series of cyclones and anticyclones propagating southwestward and westward with periods between 90 and 180 days. The behavior of the variability changes over the 6 years. Energy in the mesoscale frequencies moves slowly south and diminishes with more westward propagation in the region where the current separates from the coast. We find no evidence for a consistent forcing of the EAC by mesoscale signals propagating westward from the South Pacific basin. We suggest that the observations are consistent with variability originating between 32°S and 35°S through intrinsic instabilities of the current.

Received 17 June 2004; accepted 26 January 2005; published 23 March 2005.

Keywords: East Australian Current; mesoscale variability; western boundary current.

Index Terms: 4520 Oceanography: Physical: Eddies and mesoscale processes; 4576 Oceanography: Physical: Western boundary currents.

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Citation: Bowen, M. M., J. L. Wilkin, and W. J. Emery (2005), Variability and forcing of the East Australian Current, J. Geophys. Res., 110, C03019, doi:10.1029/2004JC002533.