Understanding Coherent Turbulence and the Roll‐Cell Transition With Lagrangian Coherent Structures and Frame‐Indifferent Fluxes

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dc.contributor.authorAksamit , Nikolas
dc.contributor.authorKaturji, Marwan
dc.contributor.authorZhang , Jiawei
dc.date.accessioned2025-02-03T20:26:21Z
dc.date.available2025-02-03T20:26:21Z
dc.date.issued2024
dc.description.abstract<jats:title>Abstract</jats:title><jats:p>We present the first analysis of frame‐indifferent (objective) fluxes and material vortices in Large Eddy Simulations of atmospheric boundary layer turbulence. We extract rotating fluid features that maintain structural coherence over time for near‐neutral, transitional, and convective boundary layers. In contrast to traditional analysis of coherent structures in turbulent boundary layers, we provide the first identification of vortex boundaries that are mathematically defined to behave as tracer transport barriers. Furthermore, these vortices are indifferent to the choice of observer reference frame and can be identified without user‐dependent velocity field decompositions. We find a strong agreement between the geometric qualities of the coherent structures we extract using our new method and classical descriptions of horizontal rolls and convective cells arising from decades of observational studies. We also quantify trends in individual vortex contributions to turbulent and advective fluxes of heat under varying atmospheric stability. Using recently developed tools from the theory of transport barrier fields, we compare diffusive momentum and heat barrier fields with the presence of rolls and cells, and determine a strong connection between heat and momentum orthogonality with the physical drivers of roll‐cell transformation. This newly employed frame‐indifferent characterization of coherent turbulent structures can be directly applied to numerical model output, and thus provides a new Lagrangian approach to understand complex scale‐dependent processes and their associated dynamics.</jats:p>
dc.identifier.citationAksamit N, Katurji M, Zhang J (2024). Understanding Coherent Turbulence and the Roll‐Cell Transition With Lagrangian Coherent Structures and Frame‐Indifferent Fluxes. Journal of Geophysical Research: Atmospheres. 129(18).
dc.identifier.doihttp://doi.org/10.1029/2024jd041490
dc.identifier.issn2169-897X
dc.identifier.issn2169-8996
dc.identifier.urihttps://hdl.handle.net/10092/107602
dc.languageen
dc.publisherAmerican Geophysical Union (AGU)
dc.rightsAll rights reserved unless otherwise stated
dc.rights.urihttp://hdl.handle.net/10092/17651
dc.subject.anzsrc37 - Earth sciences::3701 - Atmospheric sciences::370105 - Atmospheric dynamics
dc.subject.anzsrc37 - Earth sciences::3709 - Physical geography and environmental geoscience
dc.titleUnderstanding Coherent Turbulence and the Roll‐Cell Transition With Lagrangian Coherent Structures and Frame‐Indifferent Fluxes
dc.typeJournal Article
uc.collegeFaculty of Science
uc.departmentSchool of Earth and Environment
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