Geostrophic currents in the south-eastern Indian Ocean

Hamon, B. V.

doi:10.1071/mf9650255

Cited by 74 publications

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This flow is driven by the strong meridional gradient of steric height, which is represented by the southeastward oriented contours projecting seaward from the western Australian coastal boundary [ Hamon , 1965; Godfrey and Ridgway , 1985]. The slope aligned flow penetrates eastward around Cape Leeuwin to 121°E and broadens onto the continental shelf [ Cresswell and Golding , 1980; Cresswell and Peterson , 1993].…”

Section: Mean Circulation At the Coastal Boundarymentioning

confidence: 99%

The 5500‐km‐long boundary flow off western and southern Australia

2004

View full text Add to dashboard Cite

The path of the shelf edge flow off southwestern Australia is documented using results from satellite altimetry and sea surface temperature (SST) and a climatogical in situ analysis. During Austral winter a continuous current is shown to extend from its origin at North West Cape to the southern tip of Tasmania, a distance of 5500 km. Satellite SST observations and surface buoy tracks confirm the location and continuity of the current trajectory. While the Leeuwin Current is forced by the strong alongshore pressure gradient associated with the meridional portion of the western Australian coastal boundary, our results suggest that the essentially zonal shelf edge flow along the southern Australian coast arises from the setup of coastal sea level by onshore Ekman flow driven by the winter westerly wind and possibly a further alongshore pressure gradient. The timing of these two different forcing mechanisms means that the west coast pressure gradient delivers the Leeuwin Current to the south coast just as the winds reverse and are thus able to maintain the eastward passage of the current. The shelf edge flow consists of two main water masses. A low‐salinity, warm water type of tropical origin associated with the Leeuwin Current and a high‐salinity, warm water inflow formed on the western end of the Great Australian Bight continental shelf. A naming convention is proposed, the Leeuwin Current representing flow from North West Cape to the Great Australian Bight (GAB); the South Australian Current, between the eastern GAB and western Bass Strait; and the Zeehan Current off western Tasmania.

show abstract

Section: Mean Circulation At the Coastal Boundarymentioning

confidence: 99%

The 5500‐km‐long boundary flow off western and southern Australia

2004

View full text Add to dashboard Cite

show abstract

“…The longshore windstress is near 0.10 N m-2 in summer, dropping to near zero in winter (Godfrey and Ridgway, 1985). The sea level drops about 0.33 m between 20S and 32S (Hamon, 1965;Thompson, 1984;Godfrey and Ridgway, 1985) along 1I1E, which is a geopotential gradient of (1.1) [45,4 poleward. Away from the continent, this poleward push is constrained by rotation from causing a poleward flow; it is rotated to an eastward flow of 1 Py A 1 U = -]; = 7"= -0.04 m s-.…”

Section: Introductionmentioning

confidence: 99%

Continental-shelf-scale model of the Leeuwin Current

Thompson¹

1987

J Mar Res

103

View full text Add to dashboard Cite

A simple model is presented for the poleward eastern boundary current (the Leeuwin Current) off Western Australia. For continental-shelf length-scales and seasonal time-scales, the advective and time-derivative terms are small, and water flows onto the shelf until a sufficient cross-shelf pressure gradient is set up to push the same flux back. In a rotating system, the return flux takes place in a frictional (Ekman) layer at the bottom, and is synonymous with a near-bottom longshore current VB' from which is equatorward close to shore, but poleward past the 40 m isobath. If the mixed layer is deep enough, there is no upwelling, despite the upwelling-favorable winds. The light surface water is pushed down, causing a baroclinic shear enhancing the poleward current. Advection causes an intense sloping density, salinity, and tracers front. Observed u~and Py from Western Australia predict VB to be poleward in early winter at about 0.2 m S-l, and near zero in summer. The sea-level-slope lJI/y correlates highly (r~0.9) with the wind-stress u~, with a regression of (100 m)-\ both along Western Australia and western North America.

show abstract

“…Eddy motion associated with the Gulf Stream northeast of the Azores has been analyzed by Derant [1940]; the shedding of eddies by the Gulf Stream was first observed by Fuglister and Worthington [1951], and the occurrence of eddies in the Sargasso Sea has been analyzed by Fuglister [1972]. Eddies have also been observed in other parts of the oceans, in the East Australia current [Wyrtki, 1962;Hamon, 1965], off South Africa [Duncan, 1968], in Hawaiian waters [Patzert, 1969], and in the Baltic Sea [Keunecke and Magaard, 1975]. Many of these eddies are related to topographic features like seamounts and islands, but they do also occur in the open ocean as shown in statistical analysis of thermocline topography by Wyrtki [1967].…”

Section: Introductionmentioning

confidence: 99%

Eddy energy in the oceans

Wyrtki¹,

Magaard²,

Hager³

1976

J. Geophys. Res.

293

136

View full text Add to dashboard Cite

Observations of surface drift currents made by merchant ships are used to calculate the kinetic energy of the mean flow as well as the kinetic energy of the fluctuations, which is interpreted as eddy kinetic energy. The distribution of these properties is charted for the North Atlantic Ocean based on 1° squares and for the world oceans based on 5° squares. Both distributions show essentially the same features, namely, high values in the western boundary currents and in the equatorial current system and low values in the subtropical gyres. The ratio between mean energy and eddy energy is high (about 1 to 2) in the strong currents and low (about 1/20 to 1/40) in the central and eastern portions of the gyres. Comparing mean and eddy energies in ocean and atmosphere, it becomes apparent that eddy energies in the two systems are uncorrelated. The results are consistent with the idea that eddy motion in the ocean is generated in areas of strong mean shear flow and is subsequently distributed over the whole ocean.

show abstract

Geostrophic currents in the south-eastern Indian Ocean

Cited by 74 publications

References 0 publications

The 5500‐km‐long boundary flow off western and southern Australia

The 5500‐km‐long boundary flow off western and southern Australia

Continental-shelf-scale model of the Leeuwin Current

Eddy energy in the oceans

Contact Info

Product

Resources

About