Nonlinear Processes in Geophysics
Nonlinear Processes in Geophysics
NPG
Articles | Volume 28, issue 1
Articles | Volume 28, issue 1
https://doi.org/10.5194/npg-28-43-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/npg-28-43-2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.
Articles | Volume 28, issue 1
Research article
 | 
19 Jan 2021
Research article |  | 19 Jan 2021

Ordering of trajectories reveals hierarchical finite-time coherent sets in Lagrangian particle data: detecting Agulhas rings in the South Atlantic Ocean

David Wichmann, Christian Kehl, Henk A. Dijkstra, and Erik van Sebille

Data sets

Lagrangian particle dataset (2 years) for Agulhas region surface flow David Wichmann https://doi.org/10.5281/zenodo.3899942

Model code and software

OceanParcels/coherent_vortices_OPTICS: Release for publication of corresponding paper (Version v1.0) David Wichmann https://doi.org/10.5281/zenodo.4426287

OceanParcels/near_surface_microplastic: Release of code for near-surface microplastic simulations David Wichmann https://doi.org/10.5281/zenodo.4426310

Video supplement

Animation of finite-time coherent sets in the Agulhas region David Wichmann https://doi.org/10.5281/zenodo.4103741

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Short summary
Fluid parcels transported in complicated flows often contain subsets of particles that stay close over finite time intervals. We propose a new method for detecting finite-time coherent sets based on the density-based clustering technique of ordering points to identify the clustering structure (OPTICS). Unlike previous methods, our method has an intrinsic notion of coherent sets at different spatial scales. OPTICS is readily implemented in the SciPy sklearn package, making it easy to use.
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