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  • 1
    Online-Ressource
    Online-Ressource
    Cham :Springer International Publishing AG,
    Schlagwort(e): Geophysics. ; Electronic books.
    Materialart: Online-Ressource
    Seiten: 1 online resource (224 pages)
    Ausgabe: 1st ed.
    ISBN: 9783319596952
    Serie: Advances in Geophysical and Environmental Mechanics and Mathematics Series
    DDC: 530
    Sprache: Englisch
    Anmerkung: Intro -- Foreword -- Preface -- Acknowledgements -- Contents -- 1 Fundamental Equations of Fluid and Geophysical Fluid Dynamics -- 1.1 Introduction -- 1.2 The Continuum Hypothesis -- 1.3 Derivation of the Equations of Motion -- 1.3.1 Conservation of Mass -- 1.3.2 Incompressibility and Density Conservation -- 1.3.3 Momentum Equation in an Inertial Frame of Reference -- 1.4 Elementary Symmetries of the Euler's Equation -- 1.4.1 Continuous Symmetries -- 1.4.2 Discrete Symmetries -- 1.4.3 Role of Gravity in Breaking the Symmetries of the Euler's Equation -- 1.5 Momentum Equation in a Uniformly Rotating Frame of Reference -- 1.5.1 Vorticity Equation -- 1.5.2 Planar Flows with Constant Density -- 1.6 Elementary Symmetries of the Vorticity Equation -- 1.6.1 Continuous Symmetries -- 1.6.2 Discrete Symmetries -- 1.6.3 Breaking of Symmetries of the Vorticity Equation in the β Plane -- 1.7 Energy and Enstrophy Conservation -- 1.8 Conservation Laws -- 1.8.1 Kelvin's Circulation Theorem and Conservation of Circulation -- 1.8.2 Potential Vorticity and Ertel's Theorem -- 1.9 Conservation of Potential Vorticity and Models of Geophysical Flows -- 1.9.1 Shallow-Water Model with Primitive Equations -- 1.9.2 Quasi-geostrophic Shallow-Water Model -- 1.9.3 Energy and Enstrophy Conservation for the Quasi-geostrophic Shallow Water Model -- 1.9.4 Quasi-geostrophic Model of a Density Conserving Ocean -- 1.9.5 Quasi-geostrophic Model of a Potential Temperature-Conserving Atmosphere -- 1.9.6 Conservation of Pseudo-Enstrophy in a Baroclinic Quasi-geostrophic Model -- 1.9.7 Surface Quasi-geostrophic Dynamics -- 1.10 Bibliographical Note -- References -- 2 Mechanics, Symmetries and Noether's Theorem -- 2.1 Introduction -- 2.2 Hamilton's Principle of Least Action -- 2.3 Lagrangian Function, Euler--Lagrange Equations and D'Alembert's Principle. , 2.4 Covariance of the Lagrangian with Respect to Generalized Coordinates -- 2.5 Role of Constraints -- 2.6 Canonical Variables and Hamiltonian Function -- 2.7 Hamilton's Equations -- 2.8 Canonical Transformations and Generating Functions -- 2.8.1 Phase Space Volume as Canonical Invariant: Liouville's Theorem and Poisson Brackets -- 2.8.2 Casimir Invariants and Invertible Systems -- 2.9 Noether's Theorem for Point Particles -- 2.9.1 Mathematical Preliminary -- 2.9.2 Symmetry Transformations and Proof of the Theorem -- 2.9.3 Some Examples -- 2.10 Lagrangian Formulation for Fields: Lagrangian Depending on a Scalar Function -- 2.10.1 Hamiltonian for Scalar Fields -- 2.11 Noether's Theorem for Fields with the Lagrangian Depending on a Scalar Function -- 2.11.1 Mathematical Preliminary -- 2.11.2 Linking Back to the Physics -- 2.12 Lagrangian Formulation for Fields: Lagrangian Density -- 2.12.1 Hamilton's Equations for Vector Fields -- 2.12.2 Canonical Transformations and Generating Functionals for Vector Fields -- 2.13 Noether's Theorem for Fields: Lagrangian Density Dependent on Vector Functions -- 2.14 Bibliographical Note -- References -- 3 Variational Principles in Fluid Dynamics, Symmetries and Conservation Laws -- 3.1 Introduction: Lagrangian Coordinates and Labels -- 3.2 Lagrangian Density in Labelling Space -- 3.2.1 Hamilton's Equations -- 3.3 Hamilton's Principle for Fluids -- 3.4 Hamilton's Principle in the Eulerian Framework -- 3.4.1 Equivalence of the Lagrangian and Eulerian Forms of Hamilton's Principle -- 3.5 Symmetries and Conservation Laws -- 3.5.1 Preliminaries and Notation -- 3.5.2 Time Translations Symmetry -- 3.5.3 Particle Relabelling Symmetry -- 3.6 Bibliographical Note -- References -- 4 Variational Principles in Geophysical Fluid Dynamics and Approximated Equations -- 4.1 Introduction. , 4.2 Hamilton's Principle, Rotation and Incompressibility -- 4.2.1 Lagrangian Density in a Rotating Frame of Reference -- 4.2.2 Relabelling Symmetry in a Rotating Framework -- 4.2.3 Role of Incompressibility -- 4.3 A Finite Dimensional Example: Dynamics of Point Vortices -- 4.4 Approximated Equations -- 4.4.1 Rotating Shallow Water Equations -- 4.4.2 Two-Layer Shallow Water Equations -- 4.4.3 Rotating Green--Naghdi Equations -- 4.4.4 Shallow Water Semi-geostrophic Dynamics -- 4.4.5 Continuously Stratified Fluid -- 4.5 Selected Topics in Wave Dynamics -- 4.5.1 Potential Flows and Surface Water Waves -- 4.5.2 Luke's Variational Principle -- 4.5.3 Whitham's Averaged Variational Principle and Conservation of Wave Activity -- 4.5.4 Example 1: The Linear Klein--Gordon Equation -- 4.5.5 Example 2: The Nonlinear Klein--Gordon Equation -- 4.5.6 Example 3: The Korteweg--DeVries (KdV) Equation -- 4.6 Bibliographical Note and Suggestions for Further Reading -- References -- Appendix A Derivation of Equation 1.21.2) -- Appendix B Derivation of the Conservation of Potential Vorticity from Kelvin's Circulation Theorem -- Appendix C Some Simple Mathematical Properties of the Legendre Transformation -- Appendix D Derivation of Equation 2.142 -- Appendix E Invariance of the Equations of Motion 2.144 Under a Divergence Transformation -- Appendix F Functional Derivatives -- Appendix G Derivation of Equation 2.229 -- Appendix H Invariance of the Equations of Motion 2.217 Under a Divergence Transformation -- Appendix I Proofs of the Algebraic Properties of the Poisson Bracket -- Appendix J Some Identities Concerning the Jacobi Determinant -- Appendix K Derivation of 3.131 -- Appendix L Scaling the Rotating Shallow Water Lagrangian Density.
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  • 2
    Schlagwort(e): Physics ; Meteorology ; Geophysics ; Atmospheric sciences ; Fluids ; Environmental sciences
    Beschreibung / Inhaltsverzeichnis: This book describes the derivation of the equations of motion of fluids as well as the dynamics of ocean and atmospheric currents on both large and small scales through the use of variational methods. In this way the equations of Fluid and Geophysical Fluid Dynamics are re-derived making use of a unifying principle, that is Hamilton’s Principle of Least Action. The equations are analyzed within the framework of Lagrangian and Hamiltonian mechanics for continuous systems. The analysis of the equations’ symmetries and the resulting conservation laws, from Noether’s Theorem, represent the core of the description. Central to this work is the analysis of particle relabeling symmetry, which is unique for fluid dynamics and results in the conservation of potential vorticity. Different special approximations and relations, ranging from the semi-geostrophic approximation to the conservation of wave activity, are derived and analyzed. Thanks to a complete derivation of all relationships, this book is accessible for students at both undergraduate and graduate levels, as well for researchers. Students of theoretical physics and applied mathematics will recognize the existence of theoretical challenges behind the applied field of Geophysical Fluid Dynamics, while students of applied physics, meteorology and oceanography will be able to find and appreciate the fundamental relationships behind equations in this field
    Materialart: Online-Ressource
    Seiten: Online-Ressource (XVIII, 218 p, online resource)
    ISBN: 9783319596952
    Serie: Advances in Geophysical and Environmental Mechanics and Mathematics
    Sprache: Englisch
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  • 3
    Schlagwort(e): Geophysik ; Strömungsmechanik
    Materialart: Buch
    Seiten: xviii, 218 Seiten , 25 cm
    ISBN: 9783319596945
    Serie: Advances in geophysical and environmental mechanics and mathematics - AGEM2
    Sprache: Englisch
    Anmerkung: Literaturangaben
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  • 4
    Publikationsdatum: 2021-02-08
    Beschreibung: The North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO) describe the dominant part of the variability in the Northern Hemisphere extratropical troposphere. Due to the strong connection of these patterns with surface climate, recent years have shown an increased interest and an increasing skill in forecasting them. However, it is unclear what the intrinsic limits of short-term predictability for the NAO and AO patterns are. This study compares the variability and predictability of both patterns, using a range of data and index computation methods for the daily NAO/AO indices. Small deviations from Gaussianity are found and characteristic decorrelation time scales of around one week. In the analysis of the Lyapunov spectrum it is found that predictability is not significantly different between the AO and NAO or between reanalysis products. Differences exist however between the indices based on EOF analysis, which exhibit predictability time scales around 12 - 16 days, and the station-based indices, exhibiting a longer predictability of 18 - 20 days. Both of these time scales indicate predictability beyond that currently obtained in ensemble prediction models for short-term predictability. Additional longer-term predictability for these patterns may be gained through local feedbacks and remote forcing mechanisms for particular atmospheric conditions.
    Materialart: Article , PeerReviewed
    Format: text
    Format: text
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  • 5
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    Unbekannt
    Royal Society London
    In:  Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 472 (2191). Art. no. 20150864.
    Publikationsdatum: 2019-02-01
    Beschreibung: Characterizing the stratosphere as a turbulent system, temporal fluctuations often show different correlations for different time scales as well as intermittent behaviour that cannot be captured by a single scaling exponent. In this study, the different scaling laws in the long-term stratospheric variability are studied using multifractal de-trended fluctuation analysis (MF-DFA). The analysis is performed comparing four re-analysis products and different realizations of an idealized numerical model, isolating the role of topographic forcing and seasonal variability, as well as the absence of climate teleconnections and small-scale forcing. The Northern Hemisphere (NH) shows a transition of scaling exponents for time scales shorter than about 1 year, for which the variability is multifractal and scales in time with a power law corresponding to a red spectrum, to longer time scales, for which the variability is monofractal and scales in time with a power law corresponding to white noise. Southern Hemisphere (SH) variability also shows a transition at annual scales. The SH also shows a narrower dynamical range in multifractality than the NH, as seen in the generalized Hurst exponent and in the singularity spectra. The numerical integrations show that the models are able to reproduce the lowfrequency variability but are not able to fully capture the shorter term variability of the stratosphere.
    Materialart: Article , PeerReviewed
    Format: text
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  • 6
    facet.materialart.
    Unbekannt
    AMS (American Meteorological Society)
    In:  Journal of the Atmospheric Sciences, 71 (4). pp. 1494-1507.
    Publikationsdatum: 2017-10-24
    Beschreibung: Northern Hemisphere stratospheric variability is investigated with respect to chaotic behavior using time series from three different variables extracted from four different reanalysis products and two numerical model runs with different forcing. The time series show red spectra at all frequencies and the probability distribution functions show persistent deviations from a Gaussian distribution. An exception is given by the numerical model forced with perpetual winter conditions—a case that shows more variability and follows a Gaussian distribution, suggesting that the deviation from Gaussianity found in the observations is due to the transition between summer and winter variability. To search for the presence of a chaotic attractor the correlation dimension and entropy, the Lyapunov spectrum, and the associated Kaplan–Yorke dimension are estimated. A finite value of the dimensions can be computed for each variable and data product, with the correlation dimension ranging between 3.0 and 4.0 and the Kaplan–Yorke dimension between 3.3 and 5.5. The correlation entropy varies between 0.6 and 1.1. The model runs show similar values for the correlation and Lyapunov dimensions for both the seasonally forced run and the perpetual-winter run, suggesting that the structure of a possible chaotic attractor is not determined by the seasonality in the forcing, but must be given by other mechanisms.
    Materialart: Article , PeerReviewed
    Format: text
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  • 7
    facet.materialart.
    Unbekannt
    AMS (American Meteorological Society)
    In:  Journal of the Atmospheric Sciences, 71 (12). pp. 4611-4620.
    Publikationsdatum: 2017-10-24
    Beschreibung: Southern Hemisphere (SH) stratospheric variability is investigated with respect to chaotic behavior using time series from three different variables extracted from four different reanalysis products. The results are compared with the same analysis applied to the Northern Hemisphere (NH). The probability density functions (PDFs) for the SH show persistent deviations from a Gaussian distribution. The variability is given by white spectra for low frequencies, a slope of −1 for intermediate frequencies, and −3 slopes for high frequencies. Considering the time series for winter and summer separately, PDFs show a Gaussian distribution and the variability spectra change their slopes, indicating the role of the transition between winter and summer variability in shaping the time series. The correlation (D2) and the Kaplan–Yorke (DKY) dimensions are estimated. A finite value of the dimensions can be computed for each variable and data product, except for the NCEP zonal-mean zonal wind and temperature data, which violate the requirement D2 ≤ DKY, possibly owing to the presence of spurious trends and inconsistencies in the data. The value of D2 ranges between 2.6 and 3.9, while DKY ranges between 3.0 and 4.5. The results show that both D2 and DKY display large variability in their values both for different datasets and for different variables within the same dataset. The variability of the values of D2 and DKY thus leaves open the question about the existence of a low-dimensional attractor or if the finite dimensions of the system are the result of the projection of a larger attractor in a low-dimensional embedding space.
    Materialart: Article , PeerReviewed
    Format: text
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  • 8
    Publikationsdatum: 2019-01-08
    Beschreibung: The North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO) describe the dominant part of the variability in the Northern Hemisphere extratropical troposphere. Because of the strong connection of these patterns with surface climate, recent years have shown an increased interest and an increasing skill in forecasting them. However, it is unclear what the intrinsic limits of short-term predictability for the NAO and AO patterns are. This study compares the variability and predictability of both patterns, using a range of data and index computation methods for the daily NAO and AO indices. Small deviations from Gaussianity are found along with characteristic decorrelation time scales of around one week. In the analysis of the Lyapunov spectrum it is found that predictability is not significantly different between the AO and NAO or between reanalysis products. Differences exist, however, between the indices based on EOF analysis, which exhibit predictability time scales around 12–16 days, and the station-based indices, exhibiting a longer predictability of 18–20 days. Both of these time scales indicate predictability beyond that currently obtained in ensemble prediction models for short-term predictability. Additional longer-term predictability for these patterns may be gained through local feedbacks and remote forcing mechanisms for particular atmospheric conditions.
    Materialart: Conference or Workshop Item , NonPeerReviewed
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  • 9
    Publikationsdatum: 2022-05-26
    Beschreibung: Author Posting. © American Meteorological Society, 2015. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Bulletin of the American Meteorological Society 96 (2015): 1257–1279, doi:10.1175/BAMS-D-14-00015.1.
    Beschreibung: Lateral stirring is a basic oceanographic phenomenon affecting the distribution of physical, chemical, and biological fields. Eddy stirring at scales on the order of 100 km (the mesoscale) is fairly well understood and explicitly represented in modern eddy-resolving numerical models of global ocean circulation. The same cannot be said for smaller-scale stirring processes. Here, the authors describe a major oceanographic field experiment aimed at observing and understanding the processes responsible for stirring at scales of 0.1–10 km. Stirring processes of varying intensity were studied in the Sargasso Sea eddy field approximately 250 km southeast of Cape Hatteras. Lateral variability of water-mass properties, the distribution of microscale turbulence, and the evolution of several patches of inert dye were studied with an array of shipboard, autonomous, and airborne instruments. Observations were made at two sites, characterized by weak and moderate background mesoscale straining, to contrast different regimes of lateral stirring. Analyses to date suggest that, in both cases, the lateral dispersion of natural and deliberately released tracers was O(1) m2 s–1 as found elsewhere, which is faster than might be expected from traditional shear dispersion by persistent mesoscale flow and linear internal waves. These findings point to the possible importance of kilometer-scale stirring by submesoscale eddies and nonlinear internal-wave processes or the need to modify the traditional shear-dispersion paradigm to include higher-order effects. A unique aspect of the Scalable Lateral Mixing and Coherent Turbulence (LatMix) field experiment is the combination of direct measurements of dye dispersion with the concurrent multiscale hydrographic and turbulence observations, enabling evaluation of the underlying mechanisms responsible for the observed dispersion at a new level.
    Beschreibung: The bulk of this work was funded under the Scalable Lateral Mixing and Coherent Turbulence Departmental Research Initiative and the Physical Oceanography Program. The dye experiments were supported jointly by the Office of Naval Research and the National Science Foundation Physical Oceanography Program (Grants OCE-0751653 and OCE-0751734).
    Beschreibung: 2016-02-01
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Format: application/vnd.google-earth
    Format: application/pdf
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