Dr. Erik van Sebille
Climate Change Research Centre & ARC Centre of Excellence for Climate System Science,
University of New South Wales, Sydney, Australia

Using Lagrangian particles to study the pathways and time scales of the global ocean circulation

Time and place
Mon 13 May 2013, 14.00
Room C609, Arrhenius Laboratory, 6th floor

(This event has taken place)


The pathways of water masses and the connections and exchanges between ocean basins can most aptly be studied in a Lagrangian framework, where the ocean flow is traced out using particle trajectories. These trajectories can come from either numerical integration of virtual floats in high-resolution ocean models, or from the paths of free-flowing observational drifters (surface buoys or Argo floats) in the real ocean. In either case, the trajectories can be used to directly infer the time scales and pathways on which regions of the ocean are connected.
Here, I will show how Lagrangian trajectories can be used to study the pathways of water around the ocean, with particular attention to the Agulhas and Tasman leakage; two components of the inter-ocean exchanges of the Southern Hemisphere “supergyre”. I will show how Lagrangian trajectories in numerical models can be used to estimate the volumetric transports between the different ocean basins. Furthermore, I will show how the details of these trajectories can be used to infer information on the carrying agents (eddies, mean flow) of the leakages.
Finally, I will spend some time introducing a more statistical approach to the Lagrangian framework, where information from relatively short observational surface buoys can be used to form so-called super-trajectories. These super-trajectories can be grown to any desired length and can thereby provide information on the centennial-scale accumulation of marine debris in the infamous great garbage patches.