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Application of the Cross Wavelet Transform and Wavelet Coherence t...

By: S. Jevrejeva; J. C. Moore; A. Grinsted

Description: Arctic Centre, University of Lapland, Rovaniemi, Finland. Many scientists have made use of the wavelet method in analyzing time series, often using popular free software. However, at present there are no similar easy to use wavelet packages for analyzing two time series together. We discuss the cross wavelet transform and wavelet coherence for examining relationships in time frequency space between two time series. We demonstrate how phase angle statist...

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Width Dependent Collisionless Electron Dynamics in the Static Fiel...

By: M. A. Balikhin; M. Gedalin

Description: Ben-Gurion University, Beer-Sheva, Israel. We study the collisionless dynamics of electrons in the shock ramp using the numerical trajectory analysis in the model electric and magnetic fields of the shock. Even with very modest assumptions about the cross-shock potential the electron trajectories are very sensitive to the width of the ramp. The character of electron motion changes from the fully adiabatic (with conservation of v2  ...

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Structural and Statistical Properties of the Collocation Technique...

By: W. Wagner; W. Dorigo; K. Scipal; S. Zwieback

Description: Vienna University of Technology, Institute of Photogrammetry and Remote Sensing, Vienna, Austria. The validation of geophysical data sets (e.g. derived from models, exploration techniques or remote sensing) presents a formidable challenge as all products are inherently different and subject to errors. The collocation technique permits the retrieval of the error variances of different data sources without the need to specify one data set as a reference. I...

Caires, S. and Sterl, A.: Validation of ocean wind and wave data using triple collocation, J. Geophys. Res., 108, 3098–3114, 2003.; Cantrell, C. D.: Modern Mathematical Methods for Physicists and Engineers, Cambridge University Press, 2000.; Dorigo, W. A., Scipal, K., Parinussa, R. M., Liu, Y. Y., Wagner, W., de Jeu, R. A. M., and Naeimi, V.: Error characterisation of global active and passive microwave soil moisture datasets, Hydrol. Earth Syst. Sci., 14, 2605–2616,

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Soils' Seismic Property Research on the Basis of Investigation of ...

By: V. B. Zaalishvili

Description: Geophysical Institute VSC RAS, Vladikavkaz, Russia. The most important problem of seismic microzonation (SMZ) is to prove the assessment of soil conditions' influence on the response of buildings and constructions. On the modern stage, SMZ can not remain in linear positions, and empirical tools of SMZ take into account nonlinear soil properties. A number of instrumental techniques for nonlinear phenomenon investigation in soils are given in the paper. N...

Dzhindzholava, B. S.: Evaluation of the sensitivity of metrological parameters of measuring and computing systems in operation modes, in: Methods and Means of Metrological Assurance: Coll. Works NMI, Metsniereba, Tbilisi, 72–75, 1986.; Engelbrecht, Y. K. and Feldman, M. V.: Change in the spectral composition of the seismic pulses during propagation in a nonlinear medium, in: Problems of Nonlinear Seismology, Nauka, Moscow, 103–108, 1987.; Khalturin, V. I., Rautian, T. G....

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Asymmetric Tide in Lake Vallunden (Spitsbergen) : Volume 20, Issue...

By: E. G. Morozov; A. V. Marchenko

Description: Svalbard University Center, Longyearbyen, Spitsbergen, Norway. We observed strongly asymmetric tide in a channel connecting the Van Mijen Fjord and Lake Vallunden in Spitsbergen. The channel is approximately 100 m long, 10 m wide, and 1–2 m deep. Asymmetric tide was also observed in the lake. The form of the semidiurnal tide is described by a combination of only three harmonics (M2, S2 and M4) with di...

Aubrey, D. G. and Speer, P. E.: A study of non-linear tidal propagation in shallow inlet/estuarine systems, Part I: Observations, Estuarine, Coast. Shelf Sci., 21, 185–205, 1985.; Boon, J. D. and Byrne, R. J.: On basin hypsometry and the morphodynamic response of coastal inlets, Marine Geol., 40, 27–48, 1981.; Blanton, J. O., Lin, G. Q., and Elston, S. A.: Tidal current asymmetry in shallow estuaries and tidal creeks, Cont. Shelf Res., 22, 1731–1743, 2002.; Caline, F.: C...

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Chaos in Magnetoplasmas : Volume 6, Issue 3/4 (30/11/-0001)

By: B. Buti

Description: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. A nonlinear wave, in general, is equivalent to a nonlinear dynamical system, which exhibits the phenomena of chaos. By means of techniques of nonlinear dynamical systems, we have investigated the conditions under which nonlinear Alfvén waves and lower-hybrid waves can become chaotic. The role of heavy ions, in controlling the chaos in magnetoplasmas, is examined. ...

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On the Possibility of Precursors of Earthquakes in Vlf Range Obser...

By: A. K. Gwal; D. K. Sondhiya; S. Kumar

Description: Space Science Laboratory, Department of Physics, Barkatullah University, Bhopal-462026, India. Very Low Frequency (VLF) disturbances in the ionospheric electric field observed by DEMETER satellite prior to three different earthquakes that occurred during the years 2008–2009 have been presented. The electromagnetic wave data has been analyzed for few days before the earthquake with special attention to the variation in spectral characteristics and non-li...

Antonov, N. V., Lanotte, A., and Mazzino, A.: Persistence of small-scale anisotropies and anomalous scaling in a model of magnetohydrodynamics turbulence, Phys. Rev. E, 61, 6586–6605, doi:10.1103/PhysRevE.61.6586, 2000.; Artemyev, A. V., Orlova, K. G., Mourenas, D., Agapitov, O. V., and Krasnoselskikh, V. V.: Electron pitch-angle diffusion: resonant scattering by waves vs. nonadiabatic effects, Ann. Geophys., 31, 148...

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A Hybrid Variational Ensemble Data Assimilation for the High Resol...

By: O. Vignes; J. Bojarova; N. Gustafsson

Description: Swedish Meteorological and Hydrological Institute, 60176 Norrköping, Sweden. A hybrid variational ensemble data assimilation has been developed on top of the HIRLAM variational data assimilation. It provides the possibility of applying a flow-dependent background error covariance model during the data assimilation at the same time as full rank characteristics of the variational data assimilation are preserved. The hybrid formulation is based on an augme...

Berre, L.: Estimation of synoptic and mesoscale forecast error covariances in a limited area model, Mon. Weather Rev., 128, 644–667, 2000.; Berre, L. and Desroziers, G.: Filtering of background error variances and correlations, Mon. Weather Rev., 138, 3693–3720, 2010.; Bishop, C. H., Etherton, B. J., and Majumdar, S. J.: Adaptive Sampling with the Ensemble Transform Kalman Filter, Part I: Theoretical Aspects, Mon. Weather Rev., 129, 420–436, 2001.; Bojarova, J., Gustafss...

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3D Reconnection Due to Oblique Modes: a Simulation of Harris Curre...

By: J. U. Brackbill; G. Lapenta

Description: Istituto Nazionale per la Fisica della Materia and Dipartimento di Energetica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy. Simulations in three dimensions of a Harris current sheet with mass ratio, mi/me = 180, and current sheet thickness, pi/L = 0.5, suggest the existence of a linearly unstable oblique mode, which is independent from either the drift-kink or the tearing instability. The new o...

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Estimating Model Error Covariance Matrix Parameters in Extended Ka...

By: A. Ilin; J. Hakkarainen; A. Solonen; A. Bibov; M. Abbas

Description: Lappeenranta University of Technology, Lappeenranta, Finland. The extended Kalman filter (EKF) is a popular state estimation method for nonlinear dynamical models. The model error covariance matrix is often seen as a tuning parameter in EKF, which is often simply postulated by the user. In this paper, we study the filter likelihood technique for estimating the parameters of the model error covariance matrix. The approach is based on computing the likeli...

Dee, D. P.: On-line estimation of error covariance parameters for atmospheric data assimilation, Mon. Weather Rev., 123, 1128–1145, 2.0.CO;2>doi:10.1175/1520-0493(1995)123<1128:OLEOEC>2.0.CO;2, 1995.; Durbin, J. and Koopman, S. J.: Time series analysis by state space methods, Oxford University Press, New York, 2001.; Evensen, G.: Data assimilation: The ensemble Kalman filter, Springer, Berlin, 2007.; Do...

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On Resonant Interactions of Ions with Plasma Waves in a Reduced Qu...

By: E. Marsch

Description: Max-Planck-Institut für Aeronomie, Max-Planck-Str. 2, D-37191 Katlenburg-Lindau, Germany. Based on quasi-linear theory (involving pitch angle scattering), the resonant interactions between ions and waves in an anisotropic multi-component plasma are discussed. In particular, electromagnetic Alfvén and ion-cyclotron waves propagating along or obliquely to the magnetic field are considered. A set of reduced (with respect to the perpendicular...

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Hamiltonian Approach to the Derivation of Evolution Equations for ...

By: N. N. Romanova

Description: Institute of Atmospheric Physics, Russian Academy of Sciences, Pyzhevsky 3, 109017, Moscow, Russia. The dynamics of weakly nonlinear wave trains in unstable media is studied. This dynamics is investigated in the framework of a broad class of dynamical systems having a Hamiltonian structure. Two different types of instability are considered. The first one is the instability in a weakly supercritical media. The simplest example of instability of this type ...

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Phase Space Vortices in Collisionless Plasmas : Volume 10, Issue 1...

By: S. Børve; P. Michelsen; H. L. Pécseli; J. Juul Rasmussen; L. K. S. Daldorff; J. Trulsen; J. P. Lynov; P. Guio; K. Saeki

Description: University of Oslo, Institute for Theoretical Astrophysics, Box 1029 Blindern, N-0315 Oslo, Norway. Results on the formation and propagation of electron phase space vortices from laboratory experiments are summarized. The electron phase space vortices were excited in a strongly magnetized Q-machine plasma by applying a pulse to a segment of a waveguide surrounding the plasma. Depending on the temporal variation of the applied pulse, one o...

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Local Polynomial Method for Ensemble Forecast of Time Series : Vol...

By: M. Clark; B. Rajagopalan; U. Lall; Y.-i. Moon; S. Regonda

Description: Dept. of Civil, Env. and Arch. Eng., University of Colorado, Boulder, CO, USA. We present a nonparametric approach based on local polynomial regression for ensemble forecast of time series. The state space is first reconstructed by embedding the univariate time series of the response variable in a space of dimension (D) with a delay time (Τ). To obtain a forecast from a given time point t, three steps are involved: (i) the current state of ...

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Hamiltonian Description of Wave Dynamics in Nonequilibrium Media :...

By: N. N. Romanova

Description: Institute of Atmospheric Physics, Russian Academy of Sciences, Pyzhevsky 3, 109017, Moscow, Russia. We consider Hamiltonian description of weakly nonlinear wave dynamics in unstable and nonequilibrium media. We construct the appropriate canonical variables in the whole wavenumber space. The essentially new element is the construction of canonical variables in a vicinity of marginally stable points where two normal modes coalesce. The commonly used normal...

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Structure Function Measurements of the Intermittent Mhd Turbulent ...

By: A. Balogh; T. S. Horbury

Description: The Blackett Laboratory, Imperial College, London, U.K.. The intertmittent nature of turbulence within solar wind plasma has been demonstrated by several studies of spacecraft data. Using magnetic field data taken in high speed flows at high heliographic latitudes by the Ulysses probe, the character of fluctuations within the inertia] range is discussed. Structure functions are used extensively. A simple consideration of errors associated with calculatio...

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On the Problem of Optimal Approximation of the Four-wave Kinetic I...

By: V. G. Polnikov; L. Farina

Description: Centro de Previsão de Tempo e Estudos Climáticos (CPTEC), Instituto Nacional de Pesquisas Espaciais (INPE), CPTEC/INPE, Cachoeira Paulista, SP, 12630-000, Brazil. The problem of optimization of analytical and numerical approximations of Hasselmann's nonlinear kinetic integral is discussed in general form. Considering the general expression for the kinetic integral, a principle to obtain the optimal approximation is formulated. From this consi...

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Systematic Attribution of Observed Southern Hemisphere Circulation...

By: C. L. E. Franzke; I. Horenko; T. J. O'Kane; J. S. Risbey; D. P. Monselesan

Description: Meteorological Institute and Center for Earth System Research and Sustainability, University of Hamburg, Hamburg, Germany. A critical question in the global warming debate concerns the causes of the observed trends of the Southern Hemisphere (SH) atmospheric circulation over recent decades. Secular trends have been identified in the frequency of occurrence of circulation regimes, namely the positive phase of the Southern Annular Mode (SAM) and the hemisp...

Arblaster, J. M. and Meehl, G. A.: Contributions of External Forcings to Southern Annular Mode Trends, J. Climate, 19, 2896–2905, 2006.; Akaike, H.: Information Theory and an Extension of the Maximum Likelihood Principle. 1998, in Selected Papers of Hirotugu Akaike, edited by: Parzen, E., Tanabe, K., and Kitagawa, G., Springer, New York, 1998.; Barnes, E. A., Barnes, N. W., and Polvani, L. M.: Delayed Southern Hemisphere climate change induced by stratospheric ozone reco...

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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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Logit-normal Mixed Model for Indian Monsoon Rainfall Extremes : Vo...

By: L. R. Dietz; S. Chatterjee

Description: University of Minnesota, School of Statistics, Minneapolis, Minnesota, USA. Describing the nature and variability of Indian monsoon rainfall extremes is a topic of much debate in the current literature. We suggest the use of a generalized linear mixed model (GLMM), specifically, the logit-normal mixed model, to describe the underlying structure of this complex climatic event. Several GLMM algorithms are described and simulations are performed to...

Attri, S. D. and Tyagi, A.: Climate Profile of India, Tech. rep., Government of India, Ministry of Earth Sciences, India Meteorological Department, 2010.; Breslow, N. and Clayton, D.: Approximate inference in generalized linear mixed models, J. Am. Stat. Assoc.,88, 9–25, 1993.; Ghosh, S., Luniya, V., and Gupta, A.: Trend analysis of Indian summer monsoon rainfall at different spatial scales, Atmos. Sci. Lett., 10, 285–290, 2009.; Bates, D.: lme4: Mixed-Effects Modeling l...

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