Real-time prediction of atmospheric Lagrangian coherent structures based on forecast data: An application and error analysis

BozorgMagham, Amir E.; Ross, Shane D.; Schmale, David G.

doi:10.1016/j.physd.2013.05.003

Cited by 34 publications

(26 citation statements)

References 38 publications

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“…Because atmospheric Lagrangian structures can play a significant role in airborne transport, further studies were made investigating the uncertainty of the FTLE calculation and the contributions of unresolved turbulence and other forecast uncertainties. 13,14 The geometric techniques have been utilized to study several different biological systems. One of the first studies considered flows induced by a swimming jellyfish.…”

Section: Applications Of the Geometric Approachmentioning

confidence: 99%

Lagrangian based methods for coherent structure detection

Allshouse

Peacock

2015

Chaos: An Interdisciplinary Journal of Nonlinear Science

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There has been a proliferation in the development of Lagrangian analytical methods for detecting coherent structures in fluid flow transport, yielding a variety of qualitatively different approaches. We present a review of four approaches and demonstrate the utility of these methods via their application to the same sample analytic model, the canonical double-gyre flow, highlighting the pros and cons of each approach. Two of the methods, the geometric and probabilistic approaches, are well established and require velocity field data over the time interval of interest to identify particularly important material lines and surfaces, and influential regions, respectively. The other two approaches, implementing tools from cluster and braid theory, seek coherent structures based on limited trajectory data, attempting to partition the flow transport into distinct regions. All four of these approaches share the common trait that they are objective methods, meaning that their results do not depend on the frame of reference used. For each method, we also present a number of example applications ranging from blood flow and chemical reactions to ocean and atmospheric flows. The transport of material by advection in fluid systems is a process of vital and ubiquitous importance, underlying scenarios as diverse as pollutant distribution and searchand-rescue operations in the ocean to blood flow in the human body. The rapidly advancing field of Lagrangian based methods for studying flow transport has demonstrated an effective ability to find robust and significant transport features that underly the organization of flow transport in complex, unsteady flow fields. In this review, we present an overview of four of the leading Lagrangian approaches, each with their own strengths and challenges. Details of each method are presented along with an example application to the same model system, the double-gyre flow. Furthermore, we highlight a number of exciting applications and future directions to bring Lagrangian based analysis closer to implementation in real-time, real-world decision making strategies.

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Section: Applications Of the Geometric Approachmentioning

confidence: 99%

Lagrangian based methods for coherent structure detection

Allshouse

Peacock

2015

Chaos: An Interdisciplinary Journal of Nonlinear Science

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“…Thermospheric LCSs were found as material transport barriers that respond to geomagnetic activity (Wang et al, 2017). LCSs have also been found in stellar plasmas (BozorgMagham et al, 2013). Previous study of LCSs in ionospheric plasma solved fluid mass and ion and electron momentum equations for midlatitude E and F region over a 100-km-scale horizontal region (Tang & Mahalov, 2013).…”

Section: Introductionmentioning

confidence: 99%

Horseshoes in the High‐Latitude Ionosphere

et al. 2018

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In the high‐latitude ionosphere, predicting transport of polar cap patches is important because of their impact on radio communications and navigation systems. Lagrangian coherent structures (LCSs) are barriers to transport in nonlinear time‐varying flow fields, found by computing the local maximum finite‐time Lyapunov exponent (FTLE). We propose that LCSs are barriers governing patch formation. In this work, we compute and visualize the LCSs in high‐latitude ionospheric convection by computing the FTLE field with the Ionosphere‐Thermosphere Algorithm for Lagrangian Coherent Structures (ITALCS). The Weimer 2005 high‐latitude electric potential model and the 12th‐generation International Geomagnetic Reference Field (IGRF‐12) are used to generate the trueE→×trueB→ drift field at each gridpoint in the ionosphere. The trueE→×trueB→ drifts are used as the input to ITALCS. Time‐varying structures are detected in two‐dimensional ionospheric drifts at high latitudes based on locally maximum forward time FTLE values for both geomagnetically stormy and quiet periods. Typically, the dominant structure is shaped like the letter “U,” or a “horseshoe,” oriented with the curved portion of the “U” on the dayside around local noon. The LCSs during the geomagnetically stormy period have more complex topology and shift equatorward compared to the LCSs during quiet times. Analysis of a polar cap patch observed on 17 March 2015 with the Multi‐Instrument Data Analysis System indicates that a necessary condition for its formation and transport is that storm enhanced density exist poleward of the LCS.

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“…FTLE and FSLE methods have seen wide usage in both experimental [37,38,39,40] and observational [42,43,47,83,84,85,46,49,50,51] contexts.…”

Section: Lcs Diagnostic Methodsmentioning

confidence: 99%

“…The key point is whatever the definitions of LCSs, their formulation is typically (with a few exceptions, such as, for example, the burning manifolds of [32,33,34,35,36]) based solely on the Lagrangian trajectories associated with (1), and the goal is to identify fluid parcel groups that behave similarly, and are thus 'coherent.' This has been a rich area of study using both experimental [37,38,39,40] and observational [41,42,43,44,45,46,47,48,49,50,51,52,53] data.…”

Section: Introductionmentioning

confidence: 99%

Generalized Lagrangian coherent structures

Balasuriya

Ouellette

Rypina

2018

Physica D: Nonlinear Phenomena

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The notion of a Lagrangian Coherent Structure (LCS) is by now well established as a way to capture transient coherent transport dynamics in unsteady and aperiodic fluid flows that are known over finite time. We show that the concept of an LCS can be generalized to capture coherence in other quantities of interest that are transported by, but not fully locked to, the fluid. Such quantities include those with dynamic, biological, chemical, or thermodynamic relevance, such as temperature, pollutant concentration, vorticity, kinetic energy, plankton density, and so on. We provide a conceptual framework for identifying the Generalized Lagrangian Coherent Structures (GLCSs) associated with such evolving quantities. We show how LCSs can be seen as a special case within this framework, and provide an overarching discussion of various methods for identifying LCSs. The utility of this more general viewpoint is highlighted through a variety of examples. We also show that although LCSs approximate GLCSs in certain limiting situations under restrictive assumptions on how the velocity field affects the additional quantities of interest, LCSs are not in general sufficient to describe their coherent transport.

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Real-time prediction of atmospheric Lagrangian coherent structures based on forecast data: An application and error analysis

Cited by 34 publications

References 38 publications

Lagrangian based methods for coherent structure detection

Lagrangian based methods for coherent structure detection

Horseshoes in the High‐Latitude Ionosphere

Generalized Lagrangian coherent structures

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