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Anomalous Diffusion in Geophysical and Laboratory Turbulence : Vol...

By: A. Tsinober

Description: Department of Fluid Mechanics and Heat Transfer, Faculty of Engineering, Tel Aviv University, Ramat Aviv 69978 Tel Aviv, Israel. We present an overview and some new results on anomalous diffusion of passive scalar in turbulent flows (including those used by Richardson in his famous paper in 1926). The obtained results are based on the analysis of the properties of invariant quantities (energy, enstrophy, dissipation, enstrophy generation, helicity densit...

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Time-dependent Long's Equation : Volume 22, Issue 2 (06/03/2015)

By: M. Humi

Description: Department of Mathematical Sciences, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA01609, USA. Long's equation describes steady-state two-dimensional stratified flow over terrain. Its numerical solutions under various approximations were investigated by many authors. Special attention was paid to the properties of the gravity waves that are predicted to be generated as a result. In this paper we derive a time-dependent generalization ...

Baines, P. G.: Topographic effects in Stratified flows. Cambridge Univ. Press, New York, 1995.; Drazin, P. G.: On the steady flow of a fluid of variable density past an obstacle, Tellus, 13, 239–251, 1961.; Drazin, P. G. and Moore, D. W.: Steady two dimensional flow of fluid of variable density over an obstacle, J. Fluid. Mech., 28, 353–370, 1967.; Durran, D. R.: Two-Layer solutions to Long's equation for vertically propagating mountain waves, Q. J. Roy. Meteorol. Soc., ...

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A Typical Wave Wake from High-speed Vessels: Its Group Structure a...

By: A. Rodin; I. Didenkulova

Description: Laboratory of Wave Engineering, Institute of Cybernetics at Tallinn University of Technology, Akadeemia tee 21, 12618 Tallinn, Estonia. High-amplitude water waves induced by high-speed vessels are regularly observed in Tallinn Bay, the Baltic Sea, causing intense beach erosion and disturbing marine habitants in the coastal zone. Such a strong impact on the coast may be a result of a certain group structure of the wave wake. In order to understand it, her...

Brown, E. D., Buchsbaum, S. B., Hall, R. E., Penhune, J. P., Schmitt, K. F., Watson, K. M., and Wyatt, D. C.: Observations of a nonlinear solitary wave packet in the Kelvin wake of a ship, J. Fluid Mech., 204, 263–293, 1989.; Didenkulova, I., Parnell, K. E., Soomere, T., Pelinovsky, E., and Kurennoy, D.: Shoaling and runup of long waves induced by high-speed ferries in Tallinn Bay, J. Coast. Res., Special Issue, 56, 491–495, 2009a.; Didenkulova, I., Pelinovsky, E., and R...

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The Nonlinear Coupling of Electromagnetic Ion Cyclotron and Lower ...

By: L. A. Avanov; K. V. Gamayunov; E. N. Krivorutsky; G. V. Khazanov

Description: NASA, Marshall Space Flight Center, Huntsville, Alabama, USA. The excitation of lower hybrid waves (LHWs) is a widely discussed mechanism of interaction between plasma species in space, and is one of the unresolved questions of magnetospheric multi-ion plasmas. In this paper we present the morphology, dynamics, and level of LHW activity generated by electromagnetic ion cyclotron (EMIC) waves during the 2-7 May 1998 storm period on the global scale. The L...

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On the Nonstationarity of the Decadal Periodicities of the Length ...

By: G. Consolini; R. Tozzi; P. De Michelis

Description: Istituto Nazionale di Geofisica e Vulcanologia, 00143 Rome, Italy. The Earth's rotation rate is not constant, but changes on all observable timescales, from subdaily to decadal and longer. These variations are usually discussed in terms of variations in the length of the day (LoD) and are caused by processes acting within the interior, at the surface and outside of the Earth. Here, we investigate the presence of long-standing decadal variations in yearl...

Braginsky, S. I.: Short-period geomagnetic secular variation, Geophys. Astrophys. Fluid Dynam., 30, 1–78, 1984.; Buffet, B. A.: A mechanism for decade fluctuations in the length of day, Geophys. Res. Lett., 23, 3803–3806, 1996.; Currie, R. G.: The 60 year spectral line in length of day fluctuations, S. Afr. J. Sci., 69, 180–182, 1973.; Flandrin, P., Rilling, G., and Goncalvès, P., Empirical mode decomposition as a filter bank, EEE Sig. Proc. Lett., 11, 112–114, 2004.; Gi...

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Numerical Investigation of Algebraic Oceanic Turbulent Mixing-laye...

By: M. Gómez-mármol; S. Rubino; T. Chacón-rebollo

Description: Dpto. EDAN & IMUS, Universidad de Sevilla, C/Tarfia, s/n. 41012, Seville, Spain. In this paper we investigate the finite-time and asymptotic behaviour of algebraic turbulent mixing-layer models by numerical simulation. We compare the performances given by three different settings of the eddy viscosity. We consider Richardson number-based vertical eddy viscosity models. Two of these are classical algebraic turbulence models usually used in numerical simu...

Bennis, A. C., Chacón-Rebollo, T., Gómez-Mármol, M., and Lewandowski, R.: Stability of some turbulent vertical models for the ocean mixing boundary layer, Appl. Math. Lett., 21, 128-133, doi:10.1016/j.aml.2007.02.016, 2008.; Bennis, A. C., Chacón-Rebollo, T., Gómez-Mármol, M., and Lewandowski, R.: Numerical modelling of algebraic closure models of oceanic turbulent mixing layers, ESAIM-Math. Model. Num., 44, 1255-12...

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Evolution of Localized Vortices in the Presence of Stochastic Pert...

By: V. Pavlov; E. Bécu

Description: Laboratoire de MÉcanique de Lille, Boulevard Paul Langevin, 59 655 Villeneuve d'Ascq, France. We consider the evolution of a distribution of N identical point vortices when stochastic perturbations in the Hamiltonian are present. It is shown that different initial configurations of vorticity with identical integral invariants may exist. Using the Runge-Kutta scheme of order 4, it is also demonstrated that different initial configurations with the...

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Detecting Spatial Patterns with the Cumulant Function – Part 2: an...

By: P. Yiou; P. Naveau; M. Vrac; A. Bernacchia

Description: Dipartimento di Fisica, Università La Sapienza, Roma, Italy. The spatial coherence of a measured variable (e.g. temperature or pressure) is often studied to determine the regions of high variability or to find teleconnections, i.e. correlations between specific regions. While usual methods to find spatial patterns, such as Principal Components Analysis (PCA), are constrained by linear symmetries, the dependence of variables such as temperature or pressur...

Alexander, M. A., Blade, I., Newman, M., Lanzante, J. R., Lau, N. C., and Scott, J.D.: The atmospheric bridge: the influence of ENSO teleconnections on air-sea interaction over the global oceans, J. Climate, 15, 2205–2231, 2002.; Arfken, G.: The Method of Steepest Descents, in: Mathematical Methods for Physicists, 3rd Ed., Orlando, FL, Academic Press, 428–436, 1985.; Bernacchia, A. and Naveau, P.: Detecting spatial patterns with the cumulant function – Part 1: The theory...

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Ensemble Kalman Filter Assimilation of Temperature and Altimeter D...

By: N. P. Kurkowski; M. M. Rienecker; D. A. Adamec; C. L. Keppenne

Description: Science Applications International Corporation, 4600 Powder Mill Road, Beltsville, Maryland 20705, USA. To compensate for a poorly known geoid, satellite altimeter data is usually analyzed in terms of anomalies from the time mean record. When such anomalies are assimilated into an ocean model, the bias between the climatologies of the model and data is problematic. An ensemble Kalman filter (EnKF) is modified to account for the presence of a forecast-mod...

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The Evolution of Mode-2 Nonlinear Internal Waves Over the Northern...

By: D. B. Reeder; M. C. Buijsman; Y. J. Yang; F. L. Bahr; S. R. Ramp

Description: Soliton Ocean Services, Inc., Carmel Valley, CA 93924, USA. Two research cruises were conducted from the R/V OCEAN RESEARCHER 3 during 5–16 August 2011 to study the generation of high-frequency nonlinear internal waves (NLIW) over the northern Heng-Chun Ridge south of Taiwan. The primary study site, centered near 21°34' N, 120°54' E, was on top of a smaller ridge about 15 km wide by 400 m high atop the primary ridge, with a sill depth of a...

Alford, M. H., Lien, R.-C., Simmons, H., Klymak, J., Ramp, S. R., Yang, Y.-J., Tang, T.-Y., Farmer, D., and Chang, M.-H.: Speed and evolution of nonlinear internal waves transiting the South China Sea, J. Phys. Oceanogr., 40, 1338–1355, 2010.; Alford, M. H., MacKinnon, J. A., Nash, J. D., Simmons, H., Pickering, A., Klymak, J. M., Pinkel, R., Sun, O., Rainville, L., Musgrave, R., Beitzel, T., Fu, K.-H., and Lu, C.-W.: Energy flux and Dissipation in Luzon Strait: two tale...

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Percolating Magmas in Three Dimensions : Volume 14, Issue 6 (27/11...

By: S. Lovejoy; M. Carrier-nunes; H. Gaonac'H; F. Lepine; D. Schertzer

Description: GEOTOP-UQAM/McGill Centre, UQAM, Montreal, Qc., Canada. The classical models of volcanic eruptions assume that they originate as a consequence of critical stresses or critical strain rates being exceeded in the magma followed by catastrophic fragmentation. In a recent paper (Gaonac'h et al., 2003) we proposed an additional mechanism based on the properties of complex networks of overlapping bubbles; that extreme multibubble coalescence could lead to cat...

Aldibirov, M.: A model for viscous magma fragmentation during volcanic blasts, Bull. Volcanol., 56, 459–465, 1994.; Aldibirov, M. and Dingwell, D. B.: Magma fragmentation by rapid decompression, Nature, 380, 146–148, 1996.; Arbabi, S. and Sahimi, M.: Elastic properties of three-dimensional percolation networks with stretching and bond-bending forces, Phys. Rev. B, 38, 7173–7176, 1988.; Arbabi, S. and Sahimi, M.: Mechanics of disordered solids. I. Percolation on elastic n...

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Fluctuation-response Relation and Modeling in Systems with Fast an...

By: A. Vulpiani; G. Lacorata

Description: Institute of Atmospheric and Climate Sciences, National Research Council, Str. Monteroni, 73100 Lecce, Italy. We show how a general formulation of the Fluctuation-Response Relation is able to describe in detail the connection between response properties to external perturbations and spontaneous fluctuations in systems with fast and slow variables. The method is tested by using the 360-variable Lorenz-96 model, where slow and fast variables are coupled to ...

Abramov, R. and Majda, A.: New approximations and tests of linear fluctuation-response for chaotic nonlinear forced-dissipative dynamical systems, J. Nonlinear Sci., accepted, 2007.; Bell, T. L.: Climate sensitivity from fluctuation-dissipation: some simple model tests, J. Atmos. Sci., 37, 1700–1707, 1980.; Biferale, L., Daumont, I., Lacorata, G., and Vulpiani, A.: Fluctuation-response relation in turbulent systems, Phys. Rev. E, 65, 016302, 016302-1–016302-7, 2002.; Bof...

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A Mechanistic Modelling and Data Assimilation Approach to Estimate...

By: M. Lévy; O. Bernard; A. Sciandra; B. Faugeras

Description: Institut de Recherche pour le Développement (IRD), Sète, France. The principal objective of hydrodynamical-biological models is to provide estimates of the main carbon fluxes such as total and export oceanic production. These models are nitrogen based, that is to say that the variables are expressed in terms of their nitrogen content. Moreover models are calibrated using chlorophyll data sets. Therefore carbon to chlorophyll (C:Chl) and carbon to nitrogen...

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Reversal in the Nonlocal Large-scale Αω-dynamo : Volume 1, Issue 2...

By: L. K. Feschenko; G. M. Vodinchar

Description: Institute of Cosmophysical Researches and Radio Wave Propagation FEB RAS, Paratunka, Russia. Inversion of the magnetic field in a large-scale model of ΑΩ-dynamo with nonlocal α-effect is under the investigation. The model allows us to reproduce the main features of the geomagnetic field reversals. It was established that the polarity intervals in the model are distributed according to the power law. Model magnetic polarity time scale is f...

Anufriev, A. and Sokoloff, D.: Fractal properties of geodynamo models, Geophys. Astro. Fluid, 74, 207–223, doi:10.1080/03091929408203639, 1994.; Brandenburg, A. and Sandin, C.: Catastrophic alpha quenching alleviated by helicity flux and shear, Astron. Astrophys., 427, 13–21, doi:10.1051/0004-6361:20047086, 2004.; Ermushev, A. V., Rusmaikin, A. A., and Sokolof...

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Chaos in Magnetospheric Radio Emissions : Volume 9, Issue 5/6 (30/...

By: F. A. Borotto; E. L. Rempel; A. C.-l. Chian

Description: World Institute for Space Environment Research – WISER, NITP/WISER, Adelaide University, Adelaide, SA 5005, Australia. A three-wave model of auroral radio emissions near the electron plasma frequency was proposed by Chian et al. (1994) involving resonant interactions of Langmuir, whistler and Alfvén waves. Chaos can occur in the nonlinear evolution of this three-wave process in the magnetosphere. In particular, two types of intermittency,...

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Brief Communication: Weibel, Firehose and Mirror Mode Relations : ...

By: W. Baumjohann; R. A. Treumann

Description: Department of Geophysics and Environmental Sciences, Munich University, Munich, Germany. Excitation of Weibel magnetic fields in an initially non-magnetized though anisotropic plasma may trigger other low-frequency instabilities fed by pressure anisotropy. It is shown that under Weibel-like stable conditions the Weibel-like thermal fluctuation magnetic field allows for restricted Firehose-mode growth. In addition, low-frequency Whistlers can also propaga...

Landau, L. D. and Lifshitz, E. M.: Electrodynamics of Continuous Media, Pergamon Press, Oxford, 1960.; Achterberg, A. and Wiersma, J.: The Weibel instability in relativistic plasmas. I. Linear theory, II. Nonlinear theory and stabilization mechanism, Astron. Astrophys., 475, 1–18, doi:10.1051/0004-6361:20065365, 2007.; Akhiezer, A. I., Akhiezer, I. A., Sitenko, R. V., and Stepanov, K. N.: Nonlinear Theory and Fluct...

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Toward an Understanding of the Nonlinear Nature of Atmospheric Pho...

By: A. M. Feigin; I. B. Konovalov

Description: Institute of Applied Physics of the Russian Academy of Sciences, 46 Ulyanov Str., Nizhny Novgorod, 603600 Russia. The methods of nonlinear dynamics are used to reveal the origin of complicated dynamic behaviour (CDB) of a dynamic model of the mesospheric photochemical system (PCS) perturbed by diurnal variations in photolysis rates. We found that CDB appearance during the multi-day evolution is unambiguously determined by two peculiarities in the model b...

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Self-sustained Vibrations in Volcanic Areas Extracted by Independe...

By: S. De Martino; M. Falanga; M. Palo; E. De Lauro

Description: Dipartimento di Ingegneria Industriale, Salerno University, Ponte Don Melillo street, 84084, Fisciano (SA), Italy. We investigate the physical processes associated with volcanic tremor and explosions. A volcano is a complex system where a fluid source interacts with the solid edifice so generating seismic waves in a regime of low turbulence. Although the complex behavior escapes a simple universal description, the phases of activity generate stable (self-...

Abel, M., Bergweiler, S., and Gerhard-Multhaupt, R.: Synchronization of organ pipes by means of air flow coupling: experimental observations and modeling, J. Acoust. Soc. Am., 119, 2467–2475, 2006.; Acernese, F., Ciaramella, A., De Martino, S., De Rosa, R., Falanga, M., and Tagliaferri, R.: Neural networks for blind-source separation of Stromboli explosion quakes, IEEE Trans. Neural Networks 14, 167–175, 2003.; Acernese, F., Ciaramella, A., De Martino, S., Falanga, M., G...

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Joule Heating and Anomalous Resistivity in the Solar Corona : Volu...

By: S. R. Spangler

Description: Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, USA. Recent radioastronomical observations of Faraday rotation in the solar corona can be interpreted as evidence for coronal currents, with values as large as 2.5×109 Amperes (Spangler, 2007). These estimates of currents are used to develop a model for Joule heating in the corona. It is assumed that the currents are concentrated in thin current sheets, as suggested ...

Bigot, B., Galtier, S., and Politano, H.: Development of anisotropy in incompressible magnetohydrodynamic turbulence, Phys. Rev. E., 78, 066301, doi:10.1103/PhysRevE.78.066301, 2008.; Bird, M. K. and Edenhofer, P.: Remote sensing observations of the solar corona, in: Physics of the Inner Heliosphere I, edited by: Schwenn, R. and Marsch, E., Springer Verlag, 13, 1990.; Chittenden, J. P.: The effect of lower hybrid instabilities on plasma confinement in fiber Z pinches, Ph...

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A Weakly Nonlinear Model for Multi-modal Evolution of Wind-generat...

By: L. G. Redekopp; T. Sakai

Description: Department of Aerospace & Mechanical Engineering, University of Southern California, Los Angeles, CA 90089-1191, USA. A weakly nonlinear evolution model that accounts for multi-modal interaction in a small, continuously stratified lake of variable depth is derived. In particular, an evolution model for the first two vertical modes in a lake that is subject to wind stress forcing is numerically simulated. Defining modal energies, energy transfer between ...

Antenucci, J., Imberger, J., and Saggio, A.: Seasonal evolution of the basin-scale internal wave field in a large stratified lake, Limnol. Oceanogr., 45(7), 1621–1638, 2000.; Baines, P. G.: Topographic effects in strafified flows, Cambridge University press, , 1995.; Boehrer, B.: Modal response of a deep stratified lake: western Lake Constance, J. Goephys. Res., 105, 28837–28845, 2000.; Bogucki, D. J., Redekopp, L. G., and Barth, J.: Internal solitary waves in the coasta...

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