Studying an Agulhas ring's long-term pathway and decay with finite-time coherent sets.
Coherent sets in dynamical systems are regions in phase space that optimally "carry mass" with them under the system's evolution, so that these regions experience minimal leakage. The dominant tool for determining coherent sets is the transfer operator, which provides a complete description of Lagrangian mass transport. In this work, we combine existing transfer operator methods with a windowing scheme to study the spatial and temporal evolution of a so-called Agulhas ring: a large anticyclonic mesoscale eddy playing a key role in inter-ocean exchange of climate-relevant properties. Our focus is on ring decay over time and the windowing scheme enables us to study how the most coherent region (our estimate of the ring) varies in position and size over a period of more than two years. We compare the eddy-like structure and its spatio-temporal changes as revealed by our method and by a classical Eulerian approach.
School of Mathematics and Statistics, University of New South Wales, Sydney, New South Wales 2052, Australia.
Gary
G
Froyland
Department of Mathematics, University of Paderborn, 33098 Paderborn, Germany.
Christian
C
Horenkamp
IFISC (Institute for Cross-Disciplinary Physics and Complex Systems), CSIC-UIB, Palma de Mallorca 07122, Spain.
Vincent
V
Rossi
Climate Change Research Centre and ARC Centre of Excellence for Climate System Science, University of New South Wales, Sydney, New South Wales 2052, Australia.
Erik
E
van Sebille