Continental Shelf Processes
How will the key science questions be addressed?
Boundary current-eddy shelf interactions
What is the influence of Indonesian Throughflow waters on continental shelf and coastal regions of the Kimberley and Pilbara?
The majority of the Indonesian Throughflow (Indonesian Throughflow) is located along the Timor passage which continues as the South Equatorial Current. However, it is possible that under certain conditions, Indonesian Throughflow water flows onto to the continental shelf and coastal regions of the Kimberley and Pilbara. Cross-shelf arrays of currents and Temperature-Salinity data at Pilbara and Kimberley will document these episodes due to the different Temperature-Salinity characteristics between the Indonesian Throughflow water and shelf water. By relating the specific events to synoptic conditions will allow identification of the events which lead to the Indonesian Throughflow water on the shelf
Is the Holloway Current a major feature of the regional circulation in north-west Australia and if present, is it driven by alongshore and/or cross-shore pressure gradients?
What is the northward extent of the Ningaloo Current and the response of the regional currents?
What are main the interactions between Capes and Leeuwin Current?
What is the hydraulic connectivity and variability between the different regions in the northern, north-west and south-west of Australia?
What are the main driving forces (seasonal?) of shelf currents in the region?
The Holloway current is not adequately described in the region. Here, time series of currents and Temperature-Salinity are required across the shelf to determine the presence of the current and its changes through the season. The Temperature-Salinity data, together with Slocum glider tracks will allow the determination of the alongshore and cross-shore pressure gradients to determine the forcing. The Ningaloo current is characterised by colder water and thus having Temperature-Salinity data along the Pilbara line, together with sea surface temperature images will allow the documentation of the northern extent of the current. The interaction between the northward flowing Capes Current and southward flowing Leeuwin Current creates a strong shear and frontal zone which is related to the strength of the southerly winds. The HF Radar surface current data will provide detailed information on the location of the frontal zone, which can then be related to the strength of the wind. Hydraulic connectivity may be examined through numerical models although a more direct measurement would be through the use of surface drifters.
What is the relative importance of Coastally Trapped Waves on driving continental shelf circulation?
What is the tidal regime in the region? In particular, the tides in deeper water in the northern region of Australia?
Time series of currents and water levels are required together with wind fields. Correlations between currents, water levels and wind records will enable the documentation of the relative importance of the tides and wind as driving forces of the shelf circulation. Isolation of the coastally trapped wave signal through low pass-filtering the currents and water level records will indicate the relative importance of the coastally trapped waves as a driver of shelf circulation. There is very limited data on tidal variability in deeper water. Data from the deeper moorings will contribute to the validation of numerical models of the region to better define the tidal regime of the region.
Upwelling and downwelling
What is the role of alongshore density gradients generated by (1) freshwater inputs and (2) evaporation in cross shore exchange through baroclinic forcing?
What is the role of wind on cross-shore exchange?
Having cross-shore mooring transect consisting currents through the water column and Temperature-Salinity together with Slocum glider tracks will allow the determination of the crossshore changes in density and how it changes with season.