Statistical description of the East Australian Current low-frequency variability from the WOCE PCM3 array
Mauricio M. Mata A D , Susan Wijffels B , John A. Church B and Matthias Tomczak CA Department of Physics, Fundação Universidade Federal do Rio Grande (FURG), Rio Grande, RS, Brazil.
B CSIRO Marine and Atmospheric Research, GPO Box 1538, Hobart, Tas. 7001, Australia.
C The Flinders University of South Australia, SOCPES, PO Box 2100, Adelaide, SA 5001, Australia.
D Corresponding author. Email: mauricio.mata@furg.br
Marine and Freshwater Research 57(3) 273-290 https://doi.org/10.1071/MF05058
Submitted: 30 March 2005 Accepted: 4 January 2006 Published: 1 May 2006
Abstract
The in situ dataset used in the current study consists of the Pacific Current Meter 3 (PCM3) array, which was a significant part of the Australian contribution to the World Ocean Circulation Experiment to study the variability of the East Australian Current (EAC), and was operational between September 1991 and March 1994. Area-preserving spectral analysis has been used to investigate the typical time scales observed by the current meters. As a general rule, the spectra from the top layers of the shallow (1, 2 and 3) and the deep (4, 5 and 6) moorings have a distinct peak in the temporal mesoscale band (periods between 70 and 170 days), with a general redistribution of energy towards the higher-frequencies near the ocean floor. This peak has been linked with eddy variability of the EAC system, which influences the fluctuations of the current main jet. The vertical modes of the velocity profile show that the strong surface-intensified baroclinic signal of the EAC dominated the variability at mooring 4 location. Further offshore the predominant configuration resembles more closely the barotropic mode. Ultimately, spatial empirical orthogonal functions (EOF) analysis point out the impact of the presence/absence of the EAC jet in the array.
Extra keywords: direct measurements, eddies, mesoscale variability, Tasman Sea.
Acknowledgments
This paper is contribution to the CSIRO Climate Research Program and was funded in part by the Australian Greenhouse Office. M. M. Mata acknowledges the support by the Brazilian research council (CNPq, grant 200167/96–0). The current study is a contribution to the World Ocean Circulation Experiment. We thank J. A. Lima for early discussions. E. H. L. Fernandes, M. E. C. Bernardes and three anonymous reviewers provided helpful comments on the manuscript.
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