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04.04.2016 01:56 Age: 1 year
Category: Home Slider, NSW-IMOS, ABOS

The EAC Array – Revealing the Boundary Current

Data from an IMOS East Australian Current (AEC) array of moorings provide a significant advance in our understanding of the system and begin to expose its complexity.


Velocity throughout the water column as observed by the EAC Array for 21 Feb 2013, showing the array has captured the entire southward flow (in blue) of the EAC (in the upper 250m) and also a weak northward flow which extends for 2,000m at the bottom of the water column.

Sea Surface Temperature (SST) for 25 May 2012 with EAC Array observed surface velocity at 27°S

Ocean western boundary currents redistribute heat around the world and have a profound effect on the world’s climate. The East Australian Current (EAC) is the major pole-ward flowing current of the South Pacific. It provides the dominant mechanism for transporting heat from the equatorial Pacific to the cooler mid-latitudes. Satellite observations show the spatial extent and variability at the surface but the subsurface velocities and properties can extend to depths of thousands of metres and remain largely unknown.

Data from the first deployment, April 2012–August 2013, reveal the complexity and dynamic nature of the EAC, including the offshore return flow and the episodic nature of the deep northward undercurrent. The EAC array was designed to capture the entire breadth and depth of the flow. For this reason it was placed off Brisbane where the current is almost at full strength and still in jet form rather than as a complex eddy field found further south. Even so, there are a few days in June 2012 when a rarely occurring eddy pushes the main stream of the EAC further offshore than the 150km extent of the array. 

Data from the initial 18-month deployment has been calibrated and extensively quality controlled. Tidal signals have been filtered out and for ease of interpretation the data have been interpolated onto a regular grid (10m vertical, 2km horizontal resolution).  

The original dataset is available for download from the IMOS data portal.

Further details of the deployment, initial results and data preparation are presented in Sloyan et al, 2016.