Major Boundary Currents and Inter-basin Flows

How will the key science questions be addressed?

 

East Australian Current system -

  • Will the EAC strengthen with climate change as predicted?
  • Will the North Queensland Current weaken with climate change as predicted?
  • Will the bifurcation point and/or dynamics alter in a warmer ocean?

The same data streams required to detect interannual variability in the EAC and bifurcation dynamics of the South Equatorial Current in the Coral Sea will inform models forecasting future changes in basin flows over multi-decadal time scales. Without additional observations in the Gulf of Papua, the hydrodynamic model being developed for Queensland will be the richest source of information contributing to global understanding of heat transport from the South Equatorial Current to the New Guinea Coastal Undercurrent via the Hiri Current. In the future, it is reasonable to expect even more effort from the international community to gate the north-eastern boundary of the Coral Sea with permanent observing infrastructure (e.g. the Southwest Pacific Climate Experiment (SPICE program).

 

  •  What is the full-depth transport of the EAC leaving Queensland?
  • What are the short and long-term changes in the heat content of the EAC leaving Queensland?

The above questions will mainly be answered by the Bluewater and Climate Node, but the three moorings across the South East Queensland shelf and slope at 28°S will make an important contribution to measuring the inner part of the EAC.  The management of complementary infrastructure in deep water extending a ‘Brisbane Line’ across the full width of the poleward flow will be done by the Australian Bluewater Observing System.  These measurements on velocity will be supported by the Brisbane-Fiji high density XBT line, synoptic maps of sea surface temperature from remote sensing, and a well resolved model nested inside Bluelink.

 

  • Do changes in the EAC drive coastal currents in South East Queensland with impacts on sediment transport or beach erosion?

The Stradbroke National Reference Station and two slope moorings will provide key data sets to understand coastal currents in South East Queensland, particularly when teamed with observations from the wave ride buoy network. A key target will be monitoring erosion and beach replenishment, which is a focus of active coastal engineering groups at University of Queensland and Griffith University.  Again these observations are likely to feed hydrodynamic models with coupled models for waves, bottom stress, and sediment transport.