Abstract
Oceanic surface flows are dominated by finite-time mesoscale structures that separate two-dimensional flows into volumes of qualitatively different dynamical behavior. Among these, the transport boundaries around eddies are of particular interest since the enclosed volumes show a notable stability with respect to filamentation while being transported over significant distances with consequences for a multitude of different oceanic phenomena. In this paper, we present a novel method to analyze coherent transport in oceanic flows. The presented approach is purely based on convexity and aims to uncover maximal persistently star-convex (MPSC) volumes, volumes that remain star-convex with respect to a chosen reference point during a predefined time window. Since these volumes do not generate filaments, they constitute a sub-class of finite-time coherent volumes. The new perspective yields definitions for filaments, which enables the study of MPSC volume formation and dissipation. We discuss the underlying theory and present an algorithm, the material star-convex structure search, that yields comprehensible and intuitive results. In addition, we apply our method to different velocity fields and illustrate the usefulness of the method for interdisciplinary research by studying the generation of filaments in a real-world example.
Highlights
Hydrodynamic mesoscale structures separate the oceans into regions of qualitatively different dynamical behavior
The presented approach is purely based on convexity and aims to uncover maximal persistently star-convex (MPSC) volumes, volumes that remain starconvex with respect to a chosen reference point during a predefined time window
We demonstrate that it is possible to determine when which parts of the volumes generate filaments by changing the size of the time interval T and show that each MPSC volume remains coherent during the time window used for its construction
Summary
Hydrodynamic mesoscale structures separate the oceans into regions of qualitatively different dynamical behavior These jets, fronts, and eddies give rise to short-lived order in the oceans’ upper layer before they inevitably have to pass away in the face of ever-changing turbulence. During their lifetime, they have a significant effect on the distribution of hydrodynamic scalar fields like temperature, oxygen concentration, and salinity,[1,2,3,4,5] as well as nutrient concentration,[2,6] and thereby impact marine life in complex ways.[2,5–9] these structures are considered to have a relevant effect on the climate by providing focused transport of heat and salt over larger distances.[3]. The joint rotation of the enclosed water has the potential to change the interior nutrient concentration by inducing vertical velocity fields.[2,6] This way, eddies can transport warm saline water across the South Atlantic[10–12] and have a significant impact on the plankton production.[2,6,13–15]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
