Insights into the three-dimensional Lagrangian geometry of the Antarctic polar vortex

Curbelo, Jezabel; García-Garrido, Víctor J.; Mechoso, Carlos R.; Mancho, Ana M.; Wiggins, Stephen; Niang, Coumba

doi:10.5194/npg-24-379-2017

Cited by 22 publications

(19 citation statements)

References 45 publications

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“…As in our previous studies on the southern SPV( [17,12], [18]) we follow an approach based on dynamical systems theory by searching for dynamical objects from which the general behaviour of particles can be deduced. Among these objects are hyperbolic trajectories and their invariant manifolds as well as others defined in the Annex.…”

Section: The Lagrangian Descriptor Function Mmentioning

confidence: 99%

Lagrangian study of the final warming in the southern stratosphere during 2002: Part I. The vortex splitting at upper levels

et al. 2019

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The present two-part paper provides a Lagrangian perspective of the final southern warming in 2002, during which the stratospheric polar vortex (SPV) experienced a unique splitting. Part I focuses on the understanding of fundamental processes for filamentation and ultimately for vortex splitting on a selected isentropic surface in the middle stratosphere. Part II discusses the three-dimensional evolution of the selected sudden warming event. We approach the subject from a dynamical systems viewpoint and search for Lagrangian coherent structures using a Lagrangian descriptor as a tool. In this Part I we work in the idealized framework of a kinematic model that allows for an understanding of the contributing elements of the flow in late September during the splitting. We introduce a definition of kinematic SPV boundary based on a criterion for binning parcels inside and outside the vortex according to their values of the Lagrangian descriptor and associated PDF. This definition is justified by using arguments that go beyond heuristic considerations based on the potential vorticity. Next, we turn to the filamentation proceses along this kinematic boundary, and the role of Lagrangian structures in the SPV splitting. We determine a criterion for splitting based on the structure of the evolving unstable and unstable manifolds.

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Section: The Lagrangian Descriptor Function Mmentioning

confidence: 99%

Lagrangian study of the final warming in the southern stratosphere during 2002: Part I. The vortex splitting at upper levels

et al. 2019

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“…Tools from dynamical systems theory, such as Lagrangian coherent structures (LCSs), can help us to understand how fluid parcels in a flow will evolve. The study of atmospheric transport from a dynamical systems perspective has long focused on the study of large-scale phenomena [1,2,3,4,5,9,10,11,12]. This has been largely due to the larger-scale grid spacing of readily available atmospheric model data and the lack of high-resolution atmospheric measurements on a scale large enough to calculate Lagrangian data.…”

Section: Introductionmentioning

confidence: 99%

A Method for Detecting Atmospheric Lagrangian Coherent Structures Using a Single Fixed-Wing Unmanned Aircraft System

Nolan

McClelland

Woolsey

et al. 2019

Sensors

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The transport of material through the atmosphere is an issue with wide ranging implications for fields as diverse as agriculture, aviation, and human health. Due to the unsteady nature of the atmosphere, predicting how material will be transported via the Earth’s wind field is challenging. Lagrangian diagnostics, such as Lagrangian coherent structures (LCSs), have been used to discover the most significant regions of material collection or dispersion. However, Lagrangian diagnostics can be time-consuming to calculate and often rely on weather forecasts that may not be completely accurate. Recently, Eulerian diagnostics have been developed which can provide indications of LCS and have computational advantages over their Lagrangian counterparts. In this paper, a methodology is developed for estimating local Eulerian diagnostics from wind velocity data measured by a single fixed-wing unmanned aircraft system (UAS) flying in a circular arc. Using a simulation environment, driven by realistic atmospheric velocity data from the North American Mesoscale (NAM) model, it is shown that the Eulerian diagnostic estimates from UAS measurements approximate the true local Eulerian diagnostics and also predict the passage of LCSs. This methodology requires only a single flying UAS, making it easier and more affordable to implement in the field than existing alternatives, such as multiple UASs and Dopler LiDAR measurements. Our method is general enough to be applied to calculate the gradient of any scalar field.

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“…Part I also includes an Annex with a concise review of the Lagrangian concepts we use. In this Part II we examine the three-dimensional (3D) evolution of the event with special emphasis on (i) vortex splitting, and (ii) formation of barriers to transport in the 3D flow as introduced by [4] (referred to as JC17).…”

Section: Introductionmentioning

confidence: 99%

Lagrangian study of the final warming in the southern stratosphere during 2002: Part II. 3D structure

et al. 2019

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This two-part paper aims to provide a Lagrangian perspective of the final southern warming in spring of 2002, during which the stratospheric polar vortex (SPV) experienced a unique splitting. We approach the subject from a dynamical systems viewpoint and search for Lagrangian coherent structures using a Lagrangian descriptor that is applied to reanalysis data. Part I presents our methodology and focuses by means of a kinematic model, on the understanding of fundamental processes for filamentation and ultimately for vortex splitting on an isentropic surface in the middle stratosphere. The present Part II discusses the three dimensional (3D) evolution of the flow during the selected event. For this, we apply concepts developed in Part I concerning a definition of the vortex boundary that helps in the selection of trajectories to illuminate the evolving flow structures, and a criterion that allows to justify why at an isentropic level a pinched vortex will split in later times. Lagrangian structures identified include surfaces that are several kilometers deep, and which a particle trajectory analysis confirms as barriers to the flow. The role of Lagrangian structures in determining the fate of particles during the SPV splitting is discussed.. Keywords: Stratospheric warming, Lagrangian transport structures, normally hyperbolic invariant manifold (NHIM), filamentation, vortex split, links between troposphere and stratosphere

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Insights into the three-dimensional Lagrangian geometry of the Antarctic polar vortex

Cited by 22 publications

References 45 publications

Lagrangian study of the final warming in the southern stratosphere during 2002: Part I. The vortex splitting at upper levels

Lagrangian study of the final warming in the southern stratosphere during 2002: Part I. The vortex splitting at upper levels

A Method for Detecting Atmospheric Lagrangian Coherent Structures Using a Single Fixed-Wing Unmanned Aircraft System

Lagrangian study of the final warming in the southern stratosphere during 2002: Part II. 3D structure

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