CoAuthors

David Griffin (CSIRO, Australia); Madeleine Cahill (CSIRO, Australia); Bertrand Chapron (IFREMER, France); Johnny Johannessen (NERSC, Norway); Craig Donlon (ESA/ESTEC, The Netherlands)

The surface ocean current products (GlobCurrent, OSCAR, AVISO, CTOH…) are generally mainly based on the geostrophic and the Ekman contributions derived from altimetry and wind observations, respectively. However, the ocean tides are often one of the main contributors to the ocean currents on the shelves. Ignoring this contribution in the total surface currents can lead to errors of several cm/s in the surface current estimates, in some regions.
The East Australian Current (EAC), a strong geostrophic structure that flows southward along the Australian eastern coast, and the wide range of tidal regimes ranging from macro-tidal to micro-tidal that characterizes the Australian continental shelf both provide ideal conditions to thoroughly test the GlobCurrent surface current products. In addition, for more than 10 years Australia has been maintaining a network of about 50 ADCP instruments all around the country, principally through its government-supported Integrated Marine Observing System (IMOS). Finally, a large number of drifting buoys have been launched in the EAC region for more than 15 years and the observations are made available by NOAA/AOML.
This paper presents an assessment of the GlobCurrent products against IMOS current meter data and drifting buoys observations in Australia. First, the consistency between the GlobCurrent products and the in situ observations was evaluated on the EAC geostrophic structure, close to the coast and offshore. Second, an evaluation of the ocean current signal that is missed in the GlobCurrent products because of the tides was done in the wide Joseph Bonaparte Gulf, where the tidal currents can reach more than 1 m/s and represent more than 50% of the ocean surface currents in the region.