23.05.2013: FB1-Seminar

Donnerstag, 23. Mai 2013, 11:00 Hörsaal (West)

Abstract: 

"Chasing water: The Lagrangian perspective on Marine Plastics and Antarctic Bottom Water "

Erik van Sebille

Climate Change Research Centre & ARC Centre of Excellence for Climate System Science, University of New South Wales, Sydney, Australia

The pathways of water masses and the connections 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.

I will present two case studies where the Lagrangian framework is able to help answer elusive questions in physical oceanography. The first is on the mixing of Antarctic Bottom Water (AABW) in the Southern Ocean. AABW forms in three distinct locations around the continent, yet is more or less one water mass when it reaches the subtropical gyres. Using Lagrangian particles in a high-resolution ocean model, we show how these distinct source types amalgamate into one global AABW.

The second case is on the evolution and dynamics of marine debris into the great garbage patches. We have used data from observational buoys to create a statistical representation of surface advection and mixing. In a transition matrix approach, we have been able to study the formation and attribution of garbage released from anywhere around the world ocean into the five garbage patches. The main result is that these patches are much more dynamic and connected than previously thought.