Continental Shelf Processes
A major research area of the Q-IMOS Node is investigating the impact of continental shelf processes on Queensland’s coastal and marine ecosystems.
The Coral Sea has a complex bathymetry, providing considerable potential for topographic steering of ocean currents both upstream and immediately adjacent to the continental margin. Eventually, all westerly flows are forced to follow the slope bathymetry as northern (North Queensland Current) and southern (East Australian Current) boundary currents. The Great Barrier Reef occupies 210,000 km2 on a continental shelf that varies in width from just 50 km in the far northern section to 250 km at 22°S. Along most of its length, the offshore reef matrix is separated from the coast by a shallow lagoon of variable width and depth. Although there are many applications requiring knowledge of shelf currents, the complexity of the continental shelf bathymetry and inflows only allows empirical observations over a tiny fraction of the domain. Consequently, all attempts to forecast shelf currents over larger areas require the use of hydrodynamic models, and all models require appropriate forcing from the oceanic boundary to produce accurate results. Knowledge of shelf currents in this complex domain is set to improve as new models are developed.
Surveys of seabed communities throughout the Great Barrier Reef Marine Park have revealed several regions on the shelf where marine plants are unusually abundant. These regions are likely to have persistent upwelling of nutrients from deeper layers in the Coral Sea. Several physical mechanisms appear responsible and further investigation of the formation and effects of these mechanisms is required.
Key Science Questions
Boundary current-shelf interactions
- What is the influence of the EAC on longshore flow in the Great Barrier Reef Lagoon?
- What is the influence of the EAC on eddy dynamics in the lee of the Swain Reefs?
- What is the influence of the EAC on formation of the Fraser Island Gyre?
- What is the influence of the EAC on longshore flow on the shelf south of Fraser Island?
Upwelling and downwelling
- What is the influence of the EAC upon the frequency or magnitude of coastal upwelling?
- What are the determinants of persistent upwelling regions in Queensland?
- Do upwelling dynamics at any site display a seasonal signal?
- Do upwelling dynamics at any site respond to the sign of the Southern Oscillation Index?
- Are different upwelling regions in phase or independent?