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Dynamics of Turbulence Under the Effect of Stratification and Inte...

By: L. A. Ostrovsky; O. A. Druzhinin

Description: The Institute of Applied Physics, Russian Acad. Sci., Nizhny Novgorod, Russia. The objective of this paper is to study the dynamics of small-scale turbulence near a pycnocline, both in the free regime and under the action of an internal gravity wave (IW) propagating along a pycnocline, using direct numerical simulation (DNS). Turbulence is initially induced in a horizontal layer at some distance above the pycnocline. The velocity and density fields of IW ...

Anis, A. and Moum, J. N.: Surface wave-turbulence interactions: scaling ϵ(z) near the sea surface, J. Phys. Oceanogr., 25, 2025–2045, 1995.; Carruthers, D. J. and Hunt, J. C. R.: Velocity fluctuations near an interface between a turbulent region and a stably stratified layer, J. Fluid Mech., 165, 475–501, 1986.; Druzhinin, O. A., Ostrovsky, L. A., and Zilitinkevich, S. S.: The study of the effect of small-scale turbulence on internal gravity waves propa...

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Simulation of the Long-term Behaviour of a Fault with Two Asperiti...

By: S. Santini; M. Dragoni

Description: Dipartimento di Fisica, Università di Bologna, Viale Carlo Berti Pichat 8, 40127 Bologna, Italy. A system made of two sliding blocks coupled by a spring is employed to simulate the long-term behaviour of a fault with two asperities. An analytical solution is given for the motion of the system in the case of blocks having the same friction. An analysis of the phase space shows that orbits can reach a limit cycle only after entering a particular subset of ...

Beltrami, H. and Mareschal, J.-C.: Strange seismic attractor?, Pure Appl. Geophys., 141, 71–81, 1993.; Burridge, R. and Knopoff, L.: Model and theoretical seismology, B. Seismol. Soc. Am., 57, 341–371, 1967.; Byerlee, J.: Friction of rocks, Pure Appl. Geophys., 116, 616–626, 1978.; Cao, T. and Aki, K.: Seismicity simulation with a mass-spring model and a displacement hardening-softening friction law, Pure Appl. Geophys., 122, 10–23, 1984.; Cao, T. and Aki, K.: Seismicity...

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Shallow Seismicity in the Area of Greece: Its Character as Seen by...

By: L. C. Polimenakos

Description: PANGAEA Consulting Engineers, Kifissias Avenue 131, GR 11524 Athens, Greece. Occurrence of successive earthquake events in space is analysed by means of semi-stochastic processes. The analysis employs earthquakes events with M > 5.2 from the area of Greece and its surroundings (18-31° E, 34-43° N) for the time interval 1911-1985. The sequence of earthquake occurrences can be only marginally described by a first order Markov chain model. Substituta...

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Discrete Simulations of Spatio-temporal Dynamics of Small Water Bo...

By: B. S. Daya Sagar

Description: Faculty of Engineering and Technology, Melaka Campus, Multimedia University, Jalan Ayer Keroh Lama, 75450, Melaka, Malaysia. Spatio-temporal patterns of small water bodies (SWBs) under the influence of temporally varied stream flow discharge are simulated in discrete space by employing geomorphologically realistic expansion and contraction transformations. Cascades of expansion-contraction are systematically performed by synchronizing them with stream fl...

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Heliospheric Pick-up Ions Influencing Thermodynamics and Dynamics ...

By: D. Rucinski; H. J. Fahr

Description: Institut für Astrophysik und Extraterrestrische Forschung der Universität Bonn, Auf dem Hügel 71, D-53121 Bonn, Germany. Neutral interstellar H-atoms penetrate into the inner heliosphere and upon the event of ionization are converted into pick-up ions (PUIs). The magnetized solar wind flow incorporates these ions into the plasma bulk and enforces their co-motion. By nonlinear interactions with wind-entrained Alfvén waves, these ions are t...

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Representing Model Error in Ensemble Data Assimilation : Volume 21...

By: R. Buizza; N. Žagar; G. Radnoti; C. Cardinali

Description: European Centre for Medium-Range Weather Forecasts, Reading, UK. The paper investigates a method to represent model error in the ensemble data assimilation (EDA) system. The ECMWF operational EDA simulates the effect of both observations and model uncertainties. Observation errors are represented by perturbations with statistics characterized by the observation error covariance matrix whilst the model uncertainties are represented by stochastic perturba...

Desroziers, G. and Ivanov, S.: Diagnosis and adaptive tuning of observation-error parameters in a variational assimilation, Q. J. Roy. Meteor. Soc., 127, 1443–1452, 2001.; Desroziers, G., Berre, L., Chapnik, B., and Poli, P.: Diagnosis of observation, background and analysis error statistics in observation space, Q. J. Roy. Meteor. Soc., 131, 3385–3396, 2005.; Fisher, M.: Background error covariance modeling, in: Proceedings of the ECMWF Seminar on recent developments in...

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Methods to Describe Barotropic Vortices by Global Fields and Vorte...

By: W.-g. Früh

Description: Department of Mechanical and Chemical Engineering, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS, UK. Results from an experimental study of vortices in a rotating shear layer are presented. The data are in the form of maps of the instantaneous horizontal velocity field obtained by a particle tracking technique. Two fundamentally different methods to analyse time series of these velocity fields are presented and compared. One tech...

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Turbulence in the Interstellar Medium : Volume 21, Issue 3 (16/05/...

By: E. Falgarone; G. Kowal; A. C.-l. Chian; D. Falceta-gonçalves

Description: SUPA, School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9SS, UK. Turbulence is ubiquitous in the insterstellar medium and plays a major role in several processes such as the formation of dense structures and stars, the stability of molecular clouds, the amplification of magnetic fields, and the re-acceleration and diffusion of cosmic rays. Despite its importance, interstellar turbulence, like turbulence in gener...

Alexakis, A.: Non-local Phenomenology for Anisotropic Magnetohydrodynamic Turbulence, Astrophys. J., 667, L93–L96, 2007.; Alexakis, A.: Large-Scale Magnetic Fields in Magnetohydrodynamic Turbulence, Phys. Rev. Lett., 110, 084502, 2013.; Alexandrova, O., Lacombe, C., and Mangeney, A.: Spectra and anisotropy of magnetic fluctuations in the Earth's magnetosheath: Cluster observations, Ann. Geophys., 26, 3585–3596, doi:10....

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Scaling Laws of Diffusion and Time Intermittency Generated by Cohe...

By: D. Contini; A. Donateo; R. Cesari; P. Paradisi; P. Allegrini

Description: Istituto di Scienza e Tecnologie dell'Informazione A. Faedo (ISTI-CNR), Via Moruzzi 1, 56124 Pisa, Italy. We investigate the time intermittency of turbulent transport associated with the birth-death of self-organized coherent structures in the atmospheric boundary layer. We apply a threshold analysis on the increments of turbulent fluctuations to extract sequences of rapid acceleration events, which is a marker of the transition between self-organized s...

Bianco, S., Grigolini, P., and Paradisi, P.: Fluorescence intermittency in blinking quantum dots: renewal or slow modulation?, J. Chem. Phys., 123, 174704, doi:10.1063/1.2102903, 2005.; Bianco, S., Grigolini, P., and Paradisi, P.: A fluctuating environment as a source of periodic modulation Chem. Phys. Lett., 438, 336–340, 2007.; Cava, D. and Katul, G. G.: The effects of thermal stratification on clustering properties of ca...

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Characteristics of Electrostatic Solitary Waves Observed in the Pl...

By: H. Matsumoto; Y. Omura; K. Miyaguti; H. Kojima; T. Mukai

Description: Radio Atmospheric Science Center, Kyoto University, Kyoto, Japan. We present the characteristics of the Electrostatic Solitary Waves (ESW) observed by the Geotail spacecraft in the plasma sheet boundary layer based on the statistical analyses. We also discuss the results referring to a model of ESW generation due to electron beams, which is proposed by computer simulations. In this generation model, the nonlinear evolution of Langmuir waves excited by e...

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Strategies for Coupling Global and Limited-area Ensemble Kalman Fi...

By: E. Ott; I. Szunyogh; D. Merkova

Description: University of Maryland, College Park, MD, USA. This paper compares the forecast performance of four strategies for coupling global and limited area data assimilation: three strategies propagate information from the global to the limited area process, while the fourth strategy feeds back information from the limited area to the global process. All four strategies are formulated in the Local Ensemble Transform Kalman Filter (LETKF) framework.

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Juang, H. M. H., Hong, S. Y., and Kanamitsu, M.: The NCEP {R}egional {S}pectral {M}odel: {A}n Update, Bull. Am. Meteorol. Soc., 78, 2125–2143, 1997.; Juang, H. M. H. and Kanamitsu, M.: The NMC Nested {R}egional {S}pectral {M}odel, Mon. Weather Rev., 122, 3–26, 1994.; Bishop, C. H., Etherton, B. J., and Majumdar, S. J.: Adaptive Sampling with the ensemble transform {K}alman filter, {P}art {I}: Theoretical Aspects, Mon. Weather Rev., 129, 420–436, 2001.; Fertig, E. J., Bae...

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A Statistical Mechanical Approach for the Computation of the Clima...

By: V. Lucarini; S. Sarno

Description: Department of Meteorology, University of Reading, Reading, UK. The climate belongs to the class of non-equilibrium forced and dissipative systems, for which most results of quasi-equilibrium statistical mechanics, including the fluctuation-dissipation theorem, do not apply. In this paper we show for the first time how the Ruelle linear response theory, developed for studying rigorously the impact of perturbations on general observables of non-equilibriu...

Abramov, R. and Majda, A. J.: Blended response algorithms for linear fluctuation-dissipation for complex nonlinear dynamical systems, Nonlinearity, 20, 2793–2821, 2007.; Arnold, V. I.: Catastrophe Theory, Springer, Berlin, 1992.; Baladi, V.: On the susceptibility function of piecewise expanding interval maps, Commun. Math. Phys., 275, 839–859, 2007.; Brayshaw, D. J., Hoskins, B., and Blackburn, M.: The storm track response to idealised SST perturbations in an aquaplanet ...

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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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A Minimalist Model of Characteristic Earthquakes : Volume 9, Issue...

By: J. B. Gómez; A. F. Pacheco; Á. González; M. Vázquez-prada

Description: Faculty of Sciences, University of Zaragoza, Pedro Cerbuna, 12, 50009 Zaragoza, Spain. In a spirit akin to the sandpile model of self-organized criticality, we present a simple statistical model of the cellular-automaton type which simulates the role of an asperity in the dynamics of a one-dimensional fault. This model produces an earthquake spectrum similar to the characteristic-earthquake behaviour of some seismic faults. This model, th...

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Using a Variance-based Sensitivity Analysis for Analyzing the Rela...

By: C. Tiede; J. Zhao

Description: Department of Geoinformatics, University of Applied Sciences Munich, Karlstr. 6, 80333 Munich, Germany. An implementation of uncertainty analysis (UA) and quantitative global sensitivity analysis (SA) is applied to the non-linear inversion of gravity changes and three-dimensional displacement data which were measured in and active volcanic area. A didactic example is included to illustrate the computational procedure. The main emphasis is placed on the...

Saltelli, A., Tarantola, S., and Chan, K. P. S.: A quantitative model-independent methodfor global sensitivity analysis of model output, Technometrics, 41, 39–56, 1999.; Saltelli, A., Chan, K., and Scott, M. (Eds.): Sensitivity Analysis, John Wiley and Sons Ltd, 2000.; Saltelli, A., Tarantola, S., Campolongo, F., and Ratto, M.: Sensitivity Analysis in Practice, John Wiley and Sons Ltd., 2004.; Beauducel, F., Cornet, F., Suhanto, E., Duquesnoy, T., and Kasser, M.: Constra...

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Multi-scale Analysis of Teleconnection Indices: Climate Noise and ...

By: C. Franzke

Description: British Antarctic Survey, Natural Environment Research Council, Cambridge, UK. The multi-scale nature and climate noise properties of teleconnection indices are examined by using the Empirical Mode Decomposition (EMD) procedure. The EMD procedure allows for the analysis of non-stationary time series to extract physically meaningful intrinsic mode functions (IMF) and nonlinear trends. The climatologically relevant monthly mean teleconnection indices of th...

Bengtsson, L., Hagemann, S., and Hodges, K. I.: Can climate trends be calculated from reanalysis data?, J. Geophys. Res., 109, D11111, doi:10.1029/2004JD004536.; Cash, B. A. and Lee, S.: Observed Nonmodal Growth of the Pacific-North American Teleconnection Pattern, J. Climate, 14, 1017–1028, 2001.; Crommelin, D. T. and Vanden-Eijnden, E.: Reconstruction of Diffusions using spectral data from timeseries, Comm. Math. Sci., 4, 651–668, 2006.; Czaja, A., Robertson, A. W., an...

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Local Finite Time Lyapunov Exponent, Local Sampling and Probabilis...

By: D. G. Schmale III; S. D. Ross; A. E. Bozorgmagham

Description: Department of Atmospheric and Oceanic Science, University of Maryland, College Park, MD, 20742, USA. The time-varying finite time Lyapunov exponent (FTLE) is a powerful Lagrangian concept widely used for describing large-scale flow patterns and transport phenomena. However, field experiments usually have modest scales. Therefore, it is necessary to bridge between the powerful concept of FTLE and (local) field experiments. In this paper a new interpretati...

Abarbanel, H. D., Brown, R., and Kennel, M. B.: Local Lyapunov exponents computed from observed data, J. Nonlinear Sci., 2, 343–365, 1992.; Batchelor, G. K.: An Introduction to Fluid Dynamics, Cambridge University Press, 2000.; BozorgMagham, A. E. and Ross, S. D.: Atmospheric Lagrangian coherent structures considering unresolved turbulence and forecast uncertainty, Commun. Nonlinear Sci., 22, 964–979, 2015.; BozorgMagham, A. E., Ross, S. D., and Schmale, D. G.: Real-time...

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Non-stationary Extreme Models and a Climatic Application : Volume ...

By: D. Dacunha-castelle; S. Parey; M. Nogaj

Description: EDF R&D, 6 Quai Watier, 78401 Chatou, France. In this paper, we study extreme values of non-stationary climatic phenomena. In the usually considered stationary case, the modelling of extremes is only based on the behaviour of the tails of the distribution of the remainder of the data set. In the non-stationary case though, it seems reasonable to assume that the temporal dynamics of the entire data set and that of extremes are closely related and thus al...

Beniston, M. and Stephenson, D.: \newblock Extreme climatic events and their evolution under changing climatic conditions, Global Planet. Change, 44, 1–9, 2004.; Chavez-Demoulin, V.: Ajustement de vraisemblance selon Mccullagh et Tibshirani, Internal Report 97.1, Department of Mathematics, EPFL, 1997.; Coles, S.: An Introduction to Statistical Modeling of Extreme Values, Springer, New York, 2001.; Davison, A. and Ramesh, N.: Local likelihood smoothing of sample extremes,...

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Forecast Improvement in Lorenz 96 System : Volume 19, Issue 5 (02/...

By: L. Kocarev; L. Basnarkov

Description: SS. Cyril and Methodius University, Faculty of Computer Science and Engineering, P.O. Box 393, Skopje, Macedonia. Contemporary numerical weather prediction schemes are based on ensemble forecasting. Ensemble members are obtained by taking different (perturbed) models started with different initial conditions. We introduce one type of improved model that represents interactive ensemble of individual models. The improved model's performance is tested with ...

Bishop, C. M.: Pattern Recognition and Machine Learning, Springer, 2006.; Allgaier, N. A., Harris, K. D., and Danforth, C. M.: Empirical correction of a toy climate model, Phys. Rev. E, 85, 026201, doi:10.1103/PhysRevE.85.026201, 2012.; Bjerknes, V.: Dynamic Meteorology and hydrography, Part II. Kinematics, Gibson Bros., Carnegie Institute, New York, 1911.; Bougeault, P., Toth, Z., Bishop, C., Brown, B., Burridge, ...

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Search for the 531 Day-period Wobble Signal in the Polar Motion Ba...

By: H. Ding; W. B. Shen

Description: School of Geodesy and Geomatics, Key Laboratory of Geospace Environment and Geodesy of the Ministry of Education, Wuhan University, Wuhan 430079, China. In this study, we use a nonlinear and non-stationary time series analysis method, the ensemble empirical mode decomposition method (EEMD), to analyze the polar motion (PM) time series (EOP C04 series from 1962 to 2013) to find a 531 day-period wobble (531 dW) signal. The 531 dW signal has been found in t...

Carter, W. E.: Frequency modulation of the Chandlerian component of polar motion, J. Geophys. Res., 86, 1653–1658, 1981.; Carter, W. E.: Refinements of the polar motion frequency modulation hypothesis, J. Geophys. Res., 87, 7025–7028, 1982.; Chambers, D. P.: Evaluation of empirical mode decomposition for quantifying multi-decadal variations and acceleration in sea level records, Nonlin. Processes Geophys., 22, 157–166, doi:

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