Connecting the Pacific and Indian Oceans, modelling the source pathways of the East Australian and Leeuwin Currents.

Australia is unique in having a poleward flowing boundary current on both sides of the continent. The Leeuwin Current in the eastern Indian Ocean and East Australian Current (EAC) in the western Pacific Ocean are important transporters of heat and nutrients, supporting Australia’s temperate coastlines. Both currents form a pathway of water beyond their respective basins, and together with the Indonesian Throughflow and Tasman leakage, are the main conduits of interocean exchange between the Pacific and Indian Ocean. Being boundary currents, they also exchange water and nutrients with the shelf.

Here, we present results on the dynamics and variability of these two boundary currents in the eddy-resolving NEMO ocean model. Using Lagrangian particles advected within these model fields, we quantify the source pathways of Leeuwin Current and EAC water. Furthermore, we investigate the impact of eddies fluxing water into the ocean interior. Specifically, we calculate the volume fluxes between the open ocean, the boundary currents, and the inner shelf areas, and relate this to the dynamics of the system. We then show how these exchanges impact the locations where the boundary currents separate from the shelf.