Drifter observations of surface currents from the Browse Basin

Drifting objects are the best proxy to elucidate the nature of the ocean surface currents. With the advancement of satellite tracked GPS, drifter observations offers a more comprehensive understanding of the spatial and temporal aspects of the ocean surface currents. North of Australia is a data sparse region from the oceanographers viewpoint. In the Browse Basin of Australia, The University of Western Australia deployed over 150 surface drifters during 2019 to 2022. This data was used to examine the seasonality in Lagrangian characteristics of the Browse basin surface currents, in the light of the wind data from the Adele island meteorological station of the Bureau of Meteorology. This extensive deployment revealed that the prominent mean currents in the region during the first indigenous season, Mangala (December to January) was directed northeastward due to winds from the southwestward direction. For the Marrul (April), Wirralburu (May), Barrgana (June-August), Wirlburu (September) through Laja (October-November) the surface currents were directed in a westward direction following the southeasterly winds. Furthermore, our drifters could capture the high frequency to low frequency variabilities in the surface currents like tides, inertial currents and eddies, which were not always captured in the satellite observations. The drifters also revealed a region of higher mixing which is in agreement with the higher kinetic energy imagery from satellite data.