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Decadal variability of East Australian Current transport inferred from repeated high-density XBT transects, a CTD survey and satellite altimetry

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Ridgway, KR and Coleman, R and Bailey, RJ and Sutton, P (2008) Decadal variability of East Australian Current transport inferred from repeated high-density XBT transects, a CTD survey and satellite altimetry. Journal of Geophysical Research, 113 (C08039). pp. 1-18. ISSN 0148-0227

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Abstract

A time series of the net geostrophic transport through the Tasman Sea (representing
the flow of the East Australian Current (EAC) Extension) is determined from a full-depth
CTD section, 15 years of high-density XBT transects, and satellite altimetry data. A
section between Sydney and Wellington (PX34) has been occupied four times per year
since 1991 with high resolution XBT sampling. Two methods to infer baroclinic transport
from proxy data along the section are presented. The first uses shallow XBT transects to
derive geostrophic transport relative to a deep (2000 m) reference level. In the second
approach (SynTS) the subsurface temperature and salinity structure are inferred from
satellite surface height and temperature fields using a model developed from historical in
situ observations. The baroclinic transport is then computed in the usual manner. The
methods are validated using both a full-depth CTD occupation of the PX34 section and
further transects crossing the EAC in the northern Tasman Sea. There is close agreement
between the 49 XBT and SynTS PX34 transport estimates obtained between 1992 and
2006. The time series of transport through the Sydney–Wellington section shows a
range of temporal signals from eddyscale, seasonal, interannnual to decadal. In
particular, we note that the net EAC flow ranges from 5 Sv in 1995 to a maximum of
16 Sv in 2000/2001. This decadal variation confirms the EAC response to a spin-up of the
South Pacific circulation forced by changes in the basin-wide winds and matches the
changes in oceanic properties observed in the Tasman Sea.

Item Type: Article
Keywords: physical oceanography, decadal variability, East Australian Current, baroclinic transport,decadal flow
Journal or Publication Title: Journal of Geophysical Research
Page Range: pp. 1-18
ISSN: 0148-0227
Identification Number - DOI: 10.1029/2007JC004664
Additional Information:

An edited version of this paper was published by AGU. Copyright 2008 American Geophysical Union.”

Date Deposited: 04 Mar 2009 04:07
Last Modified: 18 Nov 2014 03:56
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