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2.0

Jun 28, 2018
06/18

by
Simen Å. Ellingsen

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In the study of surface waves in the presence of a shear current, a useful and much studied model is that in which the shear flow has constant vorticity. Recently it was shown by Constantin [Eur. J. Mech. B/Fluids 30 (2011) 12-16] that a flow of constant vorticity can only permit waves travelling exactly upstream or downstream, but not at oblique angles to the current, and several proofs to the same effect have appeared thereafter. Physical waves cannot possibly adhere to such a restriction,...

Topics: Fluid Dynamics, Nonlinear Sciences, Atmospheric and Oceanic Physics, Pattern Formation and...

Source: http://arxiv.org/abs/1511.02584

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12

Jun 27, 2018
06/18

by
Fabo Feng; C. A. L. Bailer-Jones

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The Milankovitch theory states that the orbital eccentricity, precession, and obliquity of the Earth influence our climate by modulating the summer insolation at high latitudes in the northern hemisphere. Despite considerable success of this theory in explaining climate change over the Pleistocene epoch (2.6 to 0.01 Myr ago), it is inconclusive with regard to which combination of orbital elements paced the 100 kyr glacial-interglacial cycles over the late Pleistocene. Here we explore the role...

Topics: Earth and Planetary Astrophysics, Atmospheric and Oceanic Physics, Astrophysics, Physics

Source: http://arxiv.org/abs/1505.02183

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0.0

Jun 30, 2018
06/18

by
Alberto Alberello; Federico Frascoli; Miguel Onorato; Alessandro Toffoli

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The dynamic and thermal regimes of climate are regulated by an exchange of energy and momentum between the atmosphere and the ocean. The role exerted by surface waves on this interchange is particularly enigmatic. Waves induce turbulence in the upper ocean by breaking and through Langmuir circulations. However, waves can directly inject energy into subsurface layers. This relates to waves not being truly irrotational and therefore the induced orbital motion being turbulent. The existence,...

Topics: Fluid Dynamics, Physics, Atmospheric and Oceanic Physics

Source: http://arxiv.org/abs/1701.02174

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3.0

Jun 27, 2018
06/18

by
Yang Wang; Avi Gozolchiani; Yosef Ashkenazy; Shlomo Havlin

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Oceanic Kelvin and Rossby waves play an important role in tropical climate and \en dynamics. Here we develop and apply a climate network approach to quantify the characteristics of \en related oceanic waves, based on sea surface height satellite data. We associate the majority of dominant long distance ($\geq 500$ km) links of the network with (i) equatorial Kelvin waves, (ii) off-equatorial Rossby waves, and (iii) tropical instability waves. Notably, we find that the location of the hubs of...

Topics: Physics and Society, Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1505.07220

3
3.0

Jun 28, 2018
06/18

by
M. Andrejczuk; F. C. Cooper; S. Juricke; T. N. Palmer; A. Weisheimer; L. Zanna

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We study the impact of three stochastic parametrizations in the ocean component of a coupled model, on forecast reliability over seasonal timescales. The relative impacts of these schemes upon the ocean mean state and ensemble spread are analyzed. The oceanic variability induced by the atmospheric forcing of the coupled system is, in most regions, the major source of ensemble spread. The largest impact on spread and bias came from the Stochastically Perturbed Parametrization Tendency (SPPT)...

Topics: Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1506.09181

2
2.0

Jun 28, 2018
06/18

by
Markus Gross; Vanesa Magar

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Recently it was demonstrated how climate data can be utilized to estimate regional wind power densities. In particular it was shown that the quality of the global scale estimate compared well with regional high resolution studies and a link between surface temperature and moist density in the estimate was presented. In the present paper the methodology is tested further, to ensure that the results using one climate data set are reliable. This is achieved by extending the study to include four...

Topics: Geophysics, Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1510.02043

2
2.0

Jun 30, 2018
06/18

by
Pascal Marquet; Jean-François Geleyn

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The squared Brunt-V\"{a}is\"{a}l\"{a} Frequency (BVF) is computed in terms of the moist entropy potential temperature recently defined in Marquet (2011). Both homogeneously saturated and non-saturated versions of $N^2$ (the squared BVF) are derived. The method employed for computing these special homogeneous cases relies on the expression of density written as a function of pressure, total water content and specific moist entropy only. The associated conservative variable...

Topics: Physics, Fluid Dynamics, Atmospheric and Oceanic Physics, Geophysics

Source: http://arxiv.org/abs/1401.2379

4
4.0

Jun 28, 2018
06/18

by
X. Barthelemy; M. L. Banner; W. L. Peirson; F. Fedele; M. Allis; F. Dias

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We revisit the classical but as yet unresolved problem of predicting the breaking onset of 2D and 3D irrotational gravity water waves. This study focuses on domains with flat bottom topography and conditions ranging from deep to intermediate depth (depth to wavelength ratio from 1 to 0.2). Our calculations based on a fully nonlinear boundary element model investigated geometric, kinematic and energetic differences between maximally recurrent and marginally breaking waves in focusing wave...

Topics: Fluid Dynamics, Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1508.06002

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8.0

Jun 27, 2018
06/18

by
Ardeshir M. Ebtehaj; Rafael L. Bras; Efi Foufoula-Georgiou

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For precipitation retrievals over land, using satellite measurements in microwave bands, it is important to properly discriminate the weak rainfall signals from strong and highly variable background surface emission. Traditionally, land rainfall retrieval methods often rely on a weak signal of rainfall scattering on high-frequency channels (85 GHz) and make use of empirical thresholding and regression-based techniques. Due to the increased ground surface signal interference, precipitation...

Topics: Atmospheric and Oceanic Physics, Data Analysis, Statistics and Probability, Physics

Source: http://arxiv.org/abs/1503.05495

1
1.0

Jun 27, 2018
06/18

by
Cesar B. Rocha; William R. Young; Ian Grooms

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We study the representation of solutions of the three-dimensional quasigeostrophic (QG) equations using Galerkin series with standard vertical modes, with particular attention to the incorporation of active surface buoyancy dynamics. We extend two existing Galerkin approaches (A and B) and develop a new Galerkin approximation (C). Approximation A, due to \cite{flierl1978}, represents the streamfunction as a truncated Galerkin series and defines the potential vorticity (PV) that satisfies the...

Topics: Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1504.03361

1
1.0

Jun 28, 2018
06/18

by
Zhiyu Liu

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The stability of stratified flows at locations in the Clyde, Irish and Celtic Seas on the UK Continental Shelf is examined. Flows are averaged over periods of 12-30 min in each hour, corresponding to the times taken to obtain reliable estimates of the rate of dissipation of turbulent kinetic energy per unit mass, $\varepsilon$. The Taylor-Goldstein equation is solved to find the maximum growth rate of small disturbances to these averaged flows, and the critical gradient Richardson number,...

Topics: Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1512.07055

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7.0

Jun 27, 2018
06/18

by
Pushkarev Andrei; Zakharov Vladimir

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We discuss several experimental and theoretical techniques historically used for Hasselmann equation wind input terms derivation. We show that recently developed ZRP technique in conjunction with high-frequency damping without spectral peak dissipation allows to reproduce more than a dozen of fetch-limited field experiments. Numerical simulation of the same Cauchy problem for different wind input terms has been performed to discuss nonlinearity implications as well as correspondence to...

Topics: Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1503.07091

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7.0

Jun 26, 2018
06/18

by
Francesco Fedele

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We propose a new conceptual framework for the prediction of rogue waves and third-order space-time extremes of wind seas that relies on the Tayfun (1980) and Janssen (2009) models coupled with Adler-Taylor (2009) theory on the Euler characteristics of random fields. Extreme statistics of the Andrea rogue wave event are examined capitalizing on European Reanalysis (ERA)-interim data. A refinement of Janssen's (2003) theory suggests that in realistic oceanic seas characterized by short-crested...

Topics: Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1501.03370

2
2.0

Jun 28, 2018
06/18

by
Philippe H. Trinh

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In 1982, Marshall P. Tulin published a report proposing a framework for reducing the equations for gravity waves generated by moving bodies into a single nonlinear differential equation solvable in closed form [Proc. 14th Symp. on Naval Hydrodynamics, 1982, pp.19-51]. Several new and puzzling issues were highlighted by Tulin, notably the existence of weak and strong wave-making regimes, and the paradoxical fact that the theory seemed to be applicable to flows at low speeds, "but not too...

Topics: Fluid Dynamics, Atmospheric and Oceanic Physics, Complex Variables, Mathematics, Physics

Source: http://arxiv.org/abs/1510.06014

4
4.0

Jun 29, 2018
06/18

by
Nicola Scafetta; Franco Milani; Antonio Bianchini; Sergio Ortolani

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An oscillation with a period of about 2100-2500 years, the Hallstatt cycle, is found in cosmogenic radioisotopes (C-14 and Be-10) and in paleoclimate records throughout the Holocene. Herein we demonstrate the astronomical origin of this cycle. Namely, this oscillation is coherent to the major stable resonance involving the four Jovian planets - Jupiter, Saturn, Uranus and Neptune - whose period is p=2318 yr. The Hallstatt cycle could derive from the rhythmic variation of the circularity of the...

Topics: Atmospheric and Oceanic Physics, Solar and Stellar Astrophysics, Physics, Earth and Planetary...

Source: http://arxiv.org/abs/1610.03096

1
1.0

Jun 29, 2018
06/18

by
Aseel Farhat; Evelyn Lunasin; Edriss S. Titi

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Analyzing the validity and success of a data assimilation algorithm when some state variable observations are not available is an important problem in meteorology and engineering. We present an improved data assimilation algorithm for recovering the exact full reference solution (i.e. the velocity and temperature) of the 3D Planetary Geostrophic model, at an exponential rate in time, by employing coarse spatial mesh observations of the temperature alone. This provides, in the case of this...

Topics: Fluid Dynamics, Atmospheric and Oceanic Physics, Analysis of PDEs, Physics, Mathematics, Geophysics

Source: http://arxiv.org/abs/1608.04770

4
4.0

Jun 30, 2018
06/18

by
Pascal Marquet

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The specific thermal enthalpy of a moist-air parcel is defined analytically following a method in which specific moist entropy is derived from the Third Law of thermodynamics. Specific thermal enthalpy is computed by integrating specific heat content with respect to absolute temperature and including the impacts of various latent heats (i.e., solid condensation, sublimation, melting, and evaporation). It is assumed that thermal enthalpies can be set to zero at $0$ K for the solid form of the...

Topics: Physics, Fluid Dynamics, Atmospheric and Oceanic Physics, Geophysics

Source: http://arxiv.org/abs/1401.3125

5
5.0

Jun 27, 2018
06/18

by
Eric Danioux; Jacques Vanneste; Oliver Bühler

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An overlooked conservation law for near-inertial waves propagating in a steady background flow provides a new perspective on the concentration of these waves in regions of anticyclonic vorticity. The conservation law implies that this concentration is a direct consequence of the decrease in spatial scales experienced by an initially homogeneous wave field. Scaling arguments and numerical simulations of a reduced-gravity model of mixed-layer near-inertial waves confirm this interpretation and...

Topics: Atmospheric and Oceanic Physics, Fluid Dynamics, Physics

Source: http://arxiv.org/abs/1503.00551

5
5.0

Jun 30, 2018
06/18

by
Pascal Marquet

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The available enthalpy is an early form of the modern thermodynamic concept of exergy, which is the generic name for the amount of work obtainable when some matter is brought to a state of equilibrium with its surroundings by means of reversible processes. It is shown in this paper that a study of the hydrodynamic properties of available enthalpy leads to a generalization of the global meteorological available energies previously introduced by Lorenz, Dutton and Pearce. A local energy cycle is...

Topics: Physics, Fluid Dynamics, Atmospheric and Oceanic Physics, Geophysics, History and Philosophy of...

Source: http://arxiv.org/abs/1402.4610

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6.0

Jun 30, 2018
06/18

by
Pascal Marquet

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Shepherd (1993) derived a general expression for the available potential energy for compressible, hydrostatic flow, where the sum of this available energy and the kinetic energy is called pseudo-energy. He demonstrated that for a special basic state the small-amplitude limit of the generalized available potential energy reduces to the well-known approximate form of Lorenz (1955) expressed in a pressure vertical coordinate. Other forms of available energies exist in atmospheric energetics and in...

Topics: Physics, Fluid Dynamics, Atmospheric and Oceanic Physics, Geophysics

Source: http://arxiv.org/abs/1402.5637

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0.0

Jun 30, 2018
06/18

by
Pascal Marquet

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A new potential vorticity is derived by using a specific entropy formulation expressed in terms of a moist-air entropy potential temperature. The new formulation is compared with Ertel's version and with others based on virtual and equivalent potential temperatures. The new potential vorticity is subject to conservative properties ensured by the Second Law applied to the moist-air material derivatives. It is shown that the upper tropospheric and stratospheric (dry) structures are nearly the...

Topics: Physics, Fluid Dynamics, Atmospheric and Oceanic Physics, Geophysics

Source: http://arxiv.org/abs/1401.2006

4
4.0

Jun 29, 2018
06/18

by
David Lannes

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This paper addresses the floating body problem which consists in studying the interaction of surface water waves with a floating body. We propose a new formulation of the water waves problem that can easily be generalized in order to take into account the presence of a floating body. The resulting equations have a compressible-incompressible structure in which the interior pressure exerted by the fluid on the floating body is a Lagrange multiplier that can be determined through the resolution...

Topics: Fluid Dynamics, Atmospheric and Oceanic Physics, Analysis of PDEs, Numerical Analysis, Physics,...

Source: http://arxiv.org/abs/1609.06136

1
1.0

Jun 30, 2018
06/18

by
Marco van Hulten; Andreas Sterl; Rob Middag; Hein de Baar; Marion Gehlen; Jean-Claude Dutay; Alessandro Tagliabue

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The distribution of dissolved aluminium in the West Atlantic Ocean shows a mirror image with that of dissolved silicic acid, hinting at intricate interactions between the ocean cycling of Al and Si. The marine biogeochemistry of Al is of interest because of its potential impact on diatom opal remineralisation, hence Si availability. Furthermore, the dissolved Al concentration at the surface ocean has been used as a tracer for dust input, dust being the most important source of the bio-essential...

Topics: Physics, Atmospheric and Oceanic Physics

Source: http://arxiv.org/abs/1405.5752

4
4.0

Jun 27, 2018
06/18

by
Elsa Dos Santos Cardoso-Bihlo; Roman O. Popovych

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Modern weather and climate prediction models are based on a system of nonlinear partial differential equations called the primitive equations. Lie symmetries of the primitive equations are computed and the structure of its maximal Lie invariance algebra, which is infinite dimensional, is studied. The maximal Lie invariance algebra for the case of a nonzero constant Coriolis parameter is mapped to the case of vanishing Coriolis force. The same mapping allows one to transform the constantly...

Topics: Atmospheric and Oceanic Physics, Mathematics, Physics, Mathematical Physics

Source: http://arxiv.org/abs/1503.04168

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7.0

Jun 27, 2018
06/18

by
David G. Dritschel; Wanming Qi; J. B. Marston

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Using complementary numerical approaches at high resolution, we study the late-time behaviour of an inviscid, incompressible two-dimensional flow on the surface of a sphere. Starting from a random initial vorticity field comprised of a small set of intermediate wavenumber spherical harmonics, we find that -- contrary to the predictions of equilibrium statistical mechanics -- the flow does not evolve into a large-scale steady state. Instead, significant unsteadiness persists, characterised by a...

Topics: Atmospheric and Oceanic Physics, Computational Physics, Nonlinear Sciences, Physics, Chaotic...

Source: http://arxiv.org/abs/1506.01015

4
4.0

Jun 28, 2018
06/18

by
X. Barthelemy; M. L. Banner; W. L. Peirson; F. Dias; M. Allis

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The kinematic properties of unsteady highly non-linear 3D wave groups have been investigated using a numerical wave tank. Although carrier wave speeds based on zero-crossing analysis remain within +-7% of linear theory predictions, crests and troughs locally undertake a systematic cyclical leaning from forward to backward as the crests/troughs transition through their maximum amplitude. Consequently, both crests and troughs slow down by approximately 15% of the linear velocity, in sharp...

Topics: Fluid Dynamics, Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1508.06001

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0.0

Jun 30, 2018
06/18

by
Valery Liapidevskii; Denys Dutykh; Marguerite Gisclon

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In this study we investigate shallow turbidity density currents and underflows from mechanical point of view. We propose a simple hyperbolic model for such flows. On one hand, our model is based on very basic conservation principles. On the other hand, the turbulent nature of the flow is also taken into account through the energy dissipation mechanism. Moreover, the mixing with the pure water along with sediments entrainment and deposition processes are considered, which makes the problem...

Topics: Fluid Dynamics, Physics, Atmospheric and Oceanic Physics

Source: http://arxiv.org/abs/1704.08024

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0.0

Jun 28, 2018
06/18

by
Marx Chhay; Denys Dutykh; Didier Clamond

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In this short note, we present a multi-symplectic structure of the Serre-Green-Naghdi (SGN) equations modelling nonlinear long surface waves in shallow water. This multi-symplectic structure allow the use of efficient finite difference or pseudo-spectral numerical schemes preserving exactly the multi-symplectic form at the discrete level.

Topics: Atmospheric and Oceanic Physics, Mathematics, Geophysics, Analysis of PDEs, Fluid Dynamics, Exactly...

Source: http://arxiv.org/abs/1511.00612

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0.0

Jun 30, 2018
06/18

by
Dimitrios Mitsotakis; Denys Dutykh; John D. Carter

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We numerically study nonlinear phenomena related to the dynamics of traveling wave solutions of the Serre equations including the stability, the persistence, the interactions and the breaking of solitary waves. The numerical method utilizes a high-order finite-element method with smooth, periodic splines in space and explicit Runge-Kutta methods in time. Other forms of solutions such as cnoidal waves and dispersive shock waves are also considered. The differences between solutions of the Serre...

Topics: Physics, Nonlinear Sciences, Fluid Dynamics, Atmospheric and Oceanic Physics, Pattern Formation and...

Source: http://arxiv.org/abs/1404.6725

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1.0

Jun 30, 2018
06/18

by
V. P. Ruban

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A nonlinear Schr\"odinger equation with variable coefficients for surface waves on a large-scale steady nonuniform current has been derived without the assumption of a relative smallness of the velocity of the current. This equation can describe with good accuracy the loss of modulation stability of a wave coming to a counter current, leading to the formation of so called rogue waves. Some theoretical estimates are compared to the numerical simulation with the exact equations for a...

Topics: Fluid Dynamics, Physics, Atmospheric and Oceanic Physics

Source: http://arxiv.org/abs/1704.04016

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4.0

Jun 27, 2018
06/18

by
Simon Birkholz; Carsten Brée; Ayhan Demircan; Günter Steinmeyer

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Using experimental data from three different rogue wave supporting systems, determinism and predictability of the underlying dynamics are evaluated with methods of nonlinear time series analysis. We included original records from the Draupner platform in the North Sea as well as time series from two optical systems in our analysis. One of the latter was measured in the infrared tail of optical fiber supercontinua, the other in the fluence profiles of multifilaments. All three data sets exhibit...

Topics: Atmospheric and Oceanic Physics, Data Analysis, Statistics and Probability, Physics

Source: http://arxiv.org/abs/1503.00706

2
2.0

Jun 30, 2018
06/18

by
William Cottrell; Miao Tian; Alex Sheremet

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The quasi-streamfunction (Psi) formalism proposed by Kim et. al. (J.W. Kim, K.J. Bai, R.C. Ertekin, W.C. Webster, J. Eng. Math. 40, 17 (2001)) provides a natural framework for systematically studying zero-vorticity waves over arbitrary bathymetry. The modified Psi-formalism developed here discards the original constraints of zero-vorticity by allowing for vertical vorticity which is the case of most interest for coastal dynamics. The problem is reformulated in terms of two dynamical equations...

Topics: Fluid Dynamics, Physics, Atmospheric and Oceanic Physics

Source: http://arxiv.org/abs/1407.7818

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0.0

Jun 30, 2018
06/18

by
Till J. W. Wagner; Alon A. Stern; Rebecca W. Dell; Ian Eisenman

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Although iceberg models have been used for decades, they have received far more widespread attention in recent years, in part due to efforts to explicitly represent icebergs in climate models. This calls for increased scrutiny of all aspects of typical iceberg models. An important component of iceberg models is the representation of iceberg capsizing, or rolling. Rolling occurs spontaneously when the ratio of iceberg width to height falls below a critical threshold. Here we examine previously...

Topics: Physics, Atmospheric and Oceanic Physics

Source: http://arxiv.org/abs/1702.06870

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0.0

Jun 28, 2018
06/18

by
Gualtiero Badin

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The role of short-wave instabilities on geostrophic turbulence is studied in a simplified model consisting of three layers in the quasi-geostrophic approximation. The linear stability analysis shows that short-wave instabilities are created by the interplay between the shear in the upper and the lower layers. If the stratification is non-uniform, in particular surface intensified, the linear growth rate is larger for short-wave instabilities than for long-wave instabilities and the layers are...

Topics: Fluid Dynamics, Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1510.04993

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1.0

Jun 30, 2018
06/18

by
M. J. Olascoaga; F. J. Beron-Vera; Y. Wang; J. Triñanes; P. Pérez-Brunius

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Ocean flows are routinely inferred from low-resolution satellite altimetry measurements of sea surface height (SSH) assuming a geostrophic balance. Recent nonlinear dynamical systems techniques have revealed that altimetry-inferred flows can support mesoscale eddies with material boundaries that do not filament for many months, thereby representing effective mechanisms for coherent transport. However, the significance of such coherent Lagrangian eddies is not free from uncertainty due to the...

Topics: Fluid Dynamics, Physics, Chaotic Dynamics, Nonlinear Sciences, Atmospheric and Oceanic Physics

Source: http://arxiv.org/abs/1704.06186

2
2.0

Jun 28, 2018
06/18

by
Y. Charles Li

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The mechanism of a rogue water wave is still unknown. One popular conjecture is that the Peregrine wave solution of the nonlinear Schr\"odinger equation (NLS) provides a mechanism. A Peregrine wave solution can be obtained by taking the infinite spatial period limit to the homoclinic solutions. In this article, from the perspective of the phase space structure of these homoclinic orbits in the infinite dimensional phase space where the NLS defines a dynamical system, we exam the...

Topics: Atmospheric and Oceanic Physics, Mathematics, Fluid Dynamics, Mathematical Physics, Physics,...

Source: http://arxiv.org/abs/1511.00620

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Jun 28, 2018
06/18

by
Stefano Sello

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In this paper, starting from the updated time series of global temperature anomalies, Ta, we show how the solar component affects the observed behavior using, as an indicator of solar activity, the Solar Sunspot Number SSN. The results that are found clearly show that the solar component has an important role and affects significantly the current observed stationary behavior of global temperature anomalies. The solar activity behavior and its future role will therefore be decisive in...

Topics: Solar and Stellar Astrophysics, Astrophysics, Atmospheric and Oceanic Physics, Data Analysis,...

Source: http://arxiv.org/abs/1512.01075

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1.0

Jun 30, 2018
06/18

by
Anna S. von der Heydt; Peter Köhler; Roderik S. W. van de Wal; Henk A. Dijkstra

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Palaeo data have been frequently used to determine the equilibrium (Charney) climate sensitivity $S^a$, and - if slow feedback processes (e.g. land ice-albedo) are adequately taken into account - they indicate a similar range as estimates based on instrumental data and climate model results. Most studies implicitly assume the (fast) feedback processes to be independent of the background climate state, e.g., equally strong during warm and cold periods. Here we assess the dependency of the fast...

Topics: Physics, Atmospheric and Oceanic Physics

Source: http://arxiv.org/abs/1403.5391

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1.0

Jun 29, 2018
06/18

by
Vladimir Zakharov; Donald Resio; Andrei Pushkarev

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The new ZRP wind input source term (Zakharov et al. 2012) is checked for its consistency via numerical simulation of Hasselmann equation. The results are compared to field experimental data, collected at different sites around the world, and theoretical predictions of self-similarity analysis. Good agreement is obtained for limited fetch and time domain statements

Topics: Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1608.03790

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0.0

Jun 29, 2018
06/18

by
E. Masciadri; F. Lascaux; A. Turchi; L. Fini

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In this contribution we present the most relevant results obtained in the context of a feasibility study (MOSE) undertaken for ESO. The principal aim of the project was to quantify the performances of a mesoscale model (Astro-Meso-NH code) in forecasting all the main atmospherical parameters relevant for the ground-based astronomical observations and the optical turbulence (CN2 and associated integrated astroclimatic parameters) above Cerro Paranal (site of the VLT) and Cerro Armazones (site of...

Topics: Astrophysics, Instrumentation and Methods for Astrophysics, Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1608.06506

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1.0

Jun 29, 2018
06/18

by
Maria Oreshenko; Kevin Heng; Brice-Olivier Demory

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Optical phase curves have become one of the common probes of exoplanetary atmospheres, but the information they encode has not been fully elucidated. Building on a diverse body of work, we upgrade the Flexible Modeling System (FMS) to include scattering in the two-stream, dual-band approximation and generate plausible, three-dimensional structures of irradiated atmospheres to study the radiative effects of aerosols or condensates. In the optical, we treat the scattering of starlight using a...

Topics: Earth and Planetary Astrophysics, Astrophysics, Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1601.03050

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Jun 29, 2018
06/18

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Elena Masciadri; Franck Lascaux; Alessio Turchi; Luca Fini

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One of the main goals of the feasibility study MOSE (MOdellig ESO Sites) is to evaluate the performances of a method conceived to forecast the optical turbulence above the ESO sites of the Very Large Telescope and the European-Extremely Large Telescope in Chile. The method implied the use of a dedicated code conceived for the optical turbulence (OT) called Astro-Meso-Nh. In this paper we present results we obtained at conclusion of this project concerning the performances of this method in...

Topics: Astrophysics, Instrumentation and Methods for Astrophysics, Atmospheric and Oceanic Physics, Physics

Source: http://arxiv.org/abs/1612.00711

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Jun 30, 2018
06/18

by
Eugene Kazantsev

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A 4D-Var data assimilation technique is applied to the rectangular-box configuration of the NEMO in order to identify the optimal parametrization of boundary conditions at lateral boundaries. The case of the staircase-shaped coastlines is studied by rotating the model grid around the center of the box. It is shown that, in some cases, the formulation of the boundary conditions at the exact boundary leads to appearance of exponentially growing modes while optimal boundary conditions allow to...

Topics: Physics, Atmospheric and Oceanic Physics

Source: http://arxiv.org/abs/1402.7201

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Jun 30, 2018
06/18

by
Fenwick C. Cooper; Laure Zanna

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An optimisation scheme is developed to accurately represent the sub-grid scale forcing of a high dimensional chaotic ocean system. Using a simple parameterisation scheme, the velocity components of a 30km resolution shallow water ocean model are optimised to have the same climatological mean and variance as that of a less viscous 7.5km resolution model. The 5 day lag-covariance is also optimised, leading to a more accurate estimate of the high resolution response to forcing using the low...

Topics: Physics, Nonlinear Sciences, Fluid Dynamics, Atmospheric and Oceanic Physics, Chaotic Dynamics

Source: http://arxiv.org/abs/1410.5722

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Jun 30, 2018
06/18

by
Pierre Auger Collaboration; Gabriele Curci

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The Pierre Auger Observatory is making significant contributions towards understanding the nature and origin of ultra-high energy cosmic rays. One of its main challenges is the monitoring of the atmosphere, both in terms of its state variables and its optical properties. The aim of this work is to analyze aerosol optical depth $\tau_{\rm a}(z)$ values measured from 2004 to 2012 at the observatory, which is located in a remote and relatively unstudied area of the Pampa Amarilla, Argentina. The...

Topics: Physics, Instrumentation and Methods for Astrophysics, High Energy Astrophysical Phenomena,...

Source: http://arxiv.org/abs/1405.7551