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  • 1
    Online Resource
    Online Resource
    Cham :Springer International Publishing AG,
    Keywords: Energy transfer-Mathematical models. ; Electronic books.
    Type of Medium: Online Resource
    Pages: 1 online resource (323 pages)
    Edition: 1st ed.
    ISBN: 9783030057046
    Series Statement: Mathematics of Planet Earth Series ; v.1
    DDC: 541.22
    Language: English
    Note: Intro -- Preface -- Acknowledgements -- Contents -- Contributors -- 1 Multi-scale Methods for Geophysical Flows -- 1.1 Introduction -- 1.2 The Governing Equations -- 1.2.1 Rotating Boussinesq Equations -- 1.2.2 Imbalance Variables -- 1.2.3 Mid-latitude Scalings -- 1.2.4 Hydrostatic Approximation -- 1.2.5 The Quasi-geostrophic Approximation on the β-plane -- 1.2.6 Rotating Shallow Water Equations -- 1.2.7 Geostrophic Scalings -- 1.2.8 Equatorial Scalings -- 1.3 Variational Principles and Hamiltonian Mechanics -- 1.3.1 Variational Principles -- 1.3.2 Variational Model Reduction -- 1.3.3 Poisson Formulation -- 1.3.4 Nambu Formulation -- 1.4 Dissipation, Turbulence, and Nonlinear Waves -- 1.4.1 Viscosity and Dissipation -- 1.4.2 Nonlinear Waves and Dynamical Systems Methods -- 1.5 Stochastic Model Reduction -- 1.5.1 Basic Setup -- 1.5.2 Slow Dynamics via the Kolmogorov Backward Equation -- 1.5.3 Direct Averaging -- 1.6 Outlook -- References -- 2 The Interior Energy Pathway: Inertia-Gravity Wave Emission by Oceanic Flows -- 2.1 Introduction -- 2.2 Rotating Shallow Water Equations and Spontaneous Emission -- 2.2.1 Shallow Water on the f-Plane -- 2.2.2 Spontaneous Emission -- 2.2.3 Beyond Shallow Water -- 2.3 Ray Equations and Wave Capture -- 2.4 Interactions Between IGWs and Density Fronts -- 2.4.1 Wave Capture in Frontal Strain -- 2.4.2 Role of IGWs in Frontal Geostrophic Adjustment -- 2.5 Diagnostics -- 2.5.1 Characterization of Flow Regimes via the Rossby Number -- 2.5.2 Linear Filters -- 2.5.3 Optimal Potential Vorticity Balance -- 2.5.4 A Simple Model for Optimal Balance -- 2.6 High-resolution Ocean General Circulation Models as a Novel Tool for Studying Spontaneous Emission -- 2.7 Discussion -- References -- 3 The IDEMIX Model: Parameterization of Internal Gravity Waves for Circulation Models of Ocean and Atmosphere. , 3.1 Internal Waves in Ocean and Atmosphere -- 3.2 The IDEMIX Model -- 3.2.1 Details of the Oceanic IDEMIX -- 3.2.2 The IDEMIX Concept Applied to Atmospheric Gravity Waves -- 3.3 Oceanic Processes in Present and Future IDEMIX -- 3.3.1 Including Energy Transfers from Mesoscale Eddies to Internal Waves -- 3.3.2 Including Wave-Mean Flow Interaction -- 3.3.3 Including Anisotropic Tidal Forcing -- 3.3.4 Including High-Frequency Compartments -- 3.3.5 Evaluation with Available Observations -- 3.4 Atmospheric Processes in IDEMIX -- 3.5 Summary -- References -- 4 Observations and Models of Low-Mode Internal Waves in the Ocean -- 4.1 Introduction -- 4.2 Numerical Modeling -- 4.2.1 Wind -- 4.2.2 Tides -- 4.3 Dissipation -- 4.4 Observations -- 4.4.1 Satellite Altimetry -- 4.4.2 Shipboard Observations -- 4.4.3 Moorings -- 4.5 Summary and Outlook -- References -- 5 Toward Consistent Subgrid Momentum Closures in Ocean Models -- 5.1 Introduction -- 5.2 Subgrid Momentum Closures -- 5.3 Quasigeostrophic Turbulence and Ocean Eddies -- 5.3.1 Two-Dimensional Turbulence -- 5.3.2 Two-Layer Geostrophic Flows -- 5.3.3 Continuously Stratified and Surface QG Dynamics -- 5.3.4 Ocean Models and Observational Evidence -- 5.4 Energy Backscatter -- 5.4.1 Models with Scalar Subgrid Energy Budget -- 5.4.2 Stochastic Superparameterizations -- 5.5 Other Closures -- 5.5.1 The Mana-Zanna Parameterization of Ocean Mesoscale Eddies -- 5.5.2 α-Models -- 5.6 Concluding Remarks -- References -- 6 Diagnosing and Parameterizing the Effects of Oceanic Eddies -- 6.1 Introduction -- 6.1.1 Isopycnal and Diapycnal Diffusion -- 6.1.2 Skew Diffusion -- 6.1.3 Diagnosing and Parameterizing the Diffusivities -- 6.2 Eddy Diffusivity Diagnostics -- 6.2.1 Lagrangian Particle Dispersion -- 6.2.2 Quasigeostrophic Linear Stability Analysis -- 6.2.3 Diffusivities from Eulerian Eddy Fluxes. , 6.3 Eddy Diffusivity Estimates in the Global Ocean -- 6.4 Limits of the Eddy Diffusion Model and Anomalous Diffusion -- 6.5 Eddy Diffusivity Parameterization -- 6.5.1 EKE Equation -- 6.6 Conclusions -- References -- 7 Entropy Production in Turbulence Parameterizations -- 7.1 The Numerically Modeled Atmosphere as a Forced-Dissipative System -- 7.2 The Entropy Budget Equation in Numerical Models of the Atmosphere -- 7.3 Moisture and Precipitation Fluxes -- 7.4 Thermal Fluxes -- 7.5 Momentum Fluxes -- 7.6 Fluctuation Theorem -- 7.7 Applicability of the Fluctuation Theorem in Geophysical Flows -- References -- 8 Reducing Spurious Diapycnal Mixing in Ocean Models -- 8.1 Introduction -- 8.2 Diagnosing Spurious Mixing -- 8.2.1 An Analytical Example -- 8.2.2 Variance Decay as a Measure for Mixing and Dissipation -- 8.2.3 Discrete Variance Decay -- 8.2.4 Applications -- 8.3 Arbitrary Lagrangian Eulerian Vertical Coordinate -- 8.3.1 tildez-Vertical Coordinate and its Effect on Spurious Mixing -- 8.3.2 Additional Techniques for Adaptive Vertical Model Layers -- 8.4 Advection Algorithms Stabilized with Isoneutral Mixing -- 8.5 ADER High Order Flux Evaluation and WENO Reconstruction -- 8.5.1 The Generalized Riemann Problem -- 8.5.2 Kernel-Based WENO Reconstruction -- 8.6 Discussion and Conclusions -- References -- 9 Diffuse Interface Approaches in Atmosphere and Ocean-Modeling and Numerical Implementation -- 9.1 Introduction -- 9.2 Diffuse Interface Approach -- 9.2.1 Notation -- 9.2.2 The Mathematical Model -- 9.3 Discretization -- 9.3.1 The Temporal Discretization -- 9.3.2 The Spatial Discretization and Energy Inequalities -- 9.3.3 A posteriori Error Estimation -- 9.4 Numerics -- 9.5 Outlook on the Direction of Research -- References -- Index.
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  • 2
    Description / Table of Contents: This book describes a recent effort combining interdisciplinary expertise within the Collaborative Research Centre “Energy transfers in atmosphere and ocean” (TRR-181), which was funded by the German Research Foundation (DFG). Energy transfers between the three dynamical regimes - small-scale turbulence, internal gravity waves and geostrophically balanced motion - are fundamental to the energy cycle of both the atmosphere and the ocean. Nonetheless, they remain poorly understood and quantified, and have yet to be adequately represented in today’s climate models. Since interactions between the dynamical regimes ultimately link the smallest scales to the largest ones through a range of complex processes, understanding these interactions is essential to constructing atmosphere and ocean models and to predicting the future climate. To this end, TRR 181 combines expertise in applied mathematics, meteorology, and physical oceanography. This book provides an overview of representative specific topics addressed by TRR 181, ranging from - a review of a coherent hierarchy of models using consistent scaling and approximations, and revealing the underlying Hamiltonian structure - a systematic derivation and implementation of stochastic and backscatter parameterisations - an exploration of the dissipation of large-scale mean or eddying balanced flow and ocean eddy parameterisations; and - a study on gravity wave breaking and mixing, the interaction of waves with the mean flow and stratification, wave-wave interactions and gravity wave parameterisations to topics of a more numerical nature such as the spurious mixing and dissipation of advection schemes, and direct numerical simulations of surface waves at the air-sea interface. In TRR 181, the process-oriented topics presented here are complemented by an operationally oriented synthesis focusing on two climate models currently being developed in Germany. In this way, the goal of TRR 181 is to help reduce the biases in and increase the accuracy of atmosphere and ocean models, and ultimately to improve climate models and climate predictions
    Type of Medium: Book
    Pages: xvi, 312 Seiten , Illustrationen, Diagramme
    ISBN: 9783030057039
    Series Statement: Mathematics of Planet Earth volume 1
    RVK:
    Language: English
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  • 3
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    Springer Verlag
    In:  EPIC3Energy Transfers in Atmosphere and Ocean, Energy Transfers in Atmosphere and Ocean, Berlin, Springer Verlag, 41 p., pp. 87-127, ISBN: 978-3-030-05703-9
    Publication Date: 2019-04-01
    Repository Name: EPIC Alfred Wegener Institut
    Type: Inbook , peerRev
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  • 4
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    ELSEVIER SCI LTD
    In:  EPIC3Ocean Modelling, ELSEVIER SCI LTD, 94, pp. 112-127, ISSN: 1463-5003
    Publication Date: 2017-01-27
    Description: This paper quantifies spurious dissipation and mixing of various advection schemes in idealised experiments of lateral shear and baroclinic instabilities in numerical simulations of a re-entrant Eady channel for configurations with large and small Rossby numbers. In addition, a two-dimensional barotropic shear instability test case is used to examine numerical dissipation of momentum advection in isolation, without any baroclinic effects. Effects of advection schemes on the evolution of background potential energy and the dynamics of the restratification process are analysed. The advection schemes for momentum and tracers are considered using several different methods including a recently developed local dissipation analysis. As highly accurate but computationally demanding schemes we apply WENO and MP5, and as more efficient lower-order total variation diminishing (TVD) schemes we use among others the SPL-max-View the MathML source13 and a third-order-upwind scheme. The analysis shows that the MP5 and SPL-max-View the MathML source13 schemes provide the most accurate results. Following our comprehensive analysis of computational costs, the MP5 scheme is approximately 2.3 times more expensive in our implementation. In contrast to the configuration with a small Rossby number, in which significant differences between schemes are apparent, the different advection schemes behave similarly for a larger Rossby number. Regions of high numerical dissipation are shown to be associated with low grid Reynolds numbers. The major outcome of the present study is that generally positive global numerical dissipation and positive background potential energy evolution delay the restratification process.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 5
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    AMER METEOROLOGICAL SOC
    In:  EPIC3Journal of Physical Oceanography, AMER METEOROLOGICAL SOC, 46, pp. 2335-2350, ISSN: 0022-3670
    Publication Date: 2016-09-19
    Description: Two surface waves can interact to produce an internal gravity wave by nonlinear resonant coupling. The process has been called spontaneous creation (SC) because it operates without internal waves being initially present. Previous studies have shown that the generated internal waves have high frequency close to the local Brunt–Väisälä frequency and wavelengths that are much larger than those of the participating surface waves, and that the spectral transfer rate of energy to the internal wave field is small compared to other generation processes. The aim of the present analysis is to provide a global map of the energy transfer into the internal wave field by surface–internal wave interaction, which is found to be about 10 23 TW in total, based on a realistic wind-sea spectrum (depending on wind speed), mixed layer depths, and stratification below the mixed layer takenfrom a state-of-the-art numericalocean model.Unlikepreviouscalculationsof the spectral transfer rate based on a vertical mode decomposition, the authors use an analytical framework that directly derives the energy flux of generated internal waves radiating downward from the mixed layer base. Since the radiated waves are of high frequency, they are trapped and dissipated in the upper ocean. The radiative flux thus feeds only a small portion of the water column, unlike in cases of wind-driven near-inertial waves that spread over the entire ocean depth before dissipating. The authors also give an estimate of the interior dis- sipation and implied vertical diffusivities due to this process. In an extended appendix, they review the modal description of the SC interaction process, completed by the corresponding counterpart, the modulation in- teraction process (MI), where a preexisting internal wave is modulated by a surface wave and interacts with another one. MI establishes a damping of the internal wave field, thus acting against SC. The authors show that SC overcomes MI for wind speeds exceeding about 10m/s.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 6
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    AMER METEOROLOGICAL SOC
    In:  EPIC3Journal of Physical Oceanography, AMER METEOROLOGICAL SOC, 47, pp. 2267-2289, ISSN: 0022-3670
    Publication Date: 2017-10-12
    Description: Small-scale turbulent mixing affects large-scale ocean processes such as the global overturning circulation but remains unresolvedin ocean models. Since the breaking of internal gravity waves is a major source of this mixing, consistent parameterizations take internal wave energetics into account. The model Internal Wave Dissipation,EnergyandMixing(IDEMIX)predictstheinternalwaveenergy,dissipationrates,anddiapycnal diffusivities based on a simplification of the spectral radiation balance of the wave field and can be used as a mixing module in global numerical simulations. In this study, it is evaluated against finestructure estimates of turbulent dissipation rates derived from Argo float observations. In addition, a novel method to compute internal gravity wave energy from finescale strain information alone is presented and applied. IDEMIX well reproducesthe magnitudeandthelarge-scalevariations ofthe Argo-derived dissipationrateandenergylevel estimates. Deficiencies arise with respect to the detailed vertical structure or the spatial extent of mixing hot spots. This points toward the need to improve the forcing functions in IDEMIX, both by implementing additionalphysicaldetailandbybetterconstrainingtheprocessesalreadyincludedinthemodel.Aprominent example is the energy transfer from the mesoscale eddies to the internal gravity waves, which is identified as an essential contributor to turbulent mixing in idealized simulations but needs to be better understood through the help of numerical, analytical, and observational studies in order to be represented realistically in ocean models.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 7
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    In:  EPIC349th International Liege colloquium, Liege, 2017-05-22-2017-05-26
    Publication Date: 2017-10-12
    Description: A host of studies has recognized that truncation errors of the discretized advection terms lead to spurious mixing and dissipation (Fig. 1) and may interact nonlinearly with turbulent mixing and transport. To investigate the impacts of spurious mixing and dissipation, we implemented some of the most novel advection schemes into the coastal ocean model GETM. We quantified spurious dissipation [Klingbeil, 2014] and mixing of the advection schemes (Fig. 3) in idealized experiments of baroclinic instabilities (Fig. 2) ranging from mesoscales (small Rossby number) to sub-mesoscales (order-one Rossby number). The processes at submesosales are distinct from mesoscale by their contribution to restratification of the mixed layer. Such analyses (Fig. 4) help to choose between highly accurate but complex schemes and lower-order less complex schemes balancing accuracy and computational costs. The major outcome of the present study is that both, numerically induced dissipation (leading to a decrease of kinetic energy) and numerically induced mixing (leading to an increase of background potential energy), artificially delay the restratification process [Mohammadi-Aragh, 2015], an effect that needs to be taken into account if parameterizations for eddy-induced mixing and dissipation are compared with numerical model simulations.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 8
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    In:  EPIC3EGU General Assembly, OS5.1/AS4.3, 2015-04-14
    Publication Date: 2015-04-28
    Description: Breaking of internal gravity waves is a major source of diapycnal mixing, driving the large-scale circulation. An energetically consistent model of the diapycnal diffusivity requires a closed model of the wave energetics, including generation, non-linear transfer and dissipation. IDEMIX meets this requirement by heavy truncation of the radiation balance equation: the energetics are formulated for a small number of compartments as integrals over respective parts of the spectral wavenumber space. The current version has compartments for up- and downward propagating waves in the frequency-wavenumber continuum and low-mode near-inertial and tidal waves. Forcing occurs by radiation of wind-driven near-inertial waves from the surface mixed layer and barotropic to baroclinic conversion of tidal energy at submarine topography. The compartments are coupled by wave-wave interactions and bottom scattering. Energy transferred by wave-wave interactions to high wavenumbers is dissipated and partly used for mixing. The model is working in physical space - the global ocean - with wave propagation by mean group velocities. IDEMIX has been studied as stand-alone module (using a Brunt-Väisälä frequency climatology and the Osborn-Cox relation to infer diapycnal diffusivities) and in a coupled mode in a global OGCM. The inferred diapycnal diffusivities have a reasonable size and plausible spatial pattern. We report on new developments in IDEMIX as the incorporation of topographic lee-waves and wave-mean flow interaction.
    Repository Name: EPIC Alfred Wegener Institut
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  • 9
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    In:  EPIC3WTD workshop, Ilse of Vilm, 2015-08-31
    Publication Date: 2015-09-07
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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  • 10
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    In:  EPIC3Seminar, Institut fuer Atmosphäre und Umwelt Goethe-Universität Frankfurt, 2015-07-16-2015-07-16
    Publication Date: 2015-07-22
    Repository Name: EPIC Alfred Wegener Institut
    Type: Conference , notRev
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