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Self-breeding: a New Method to Estimate Local Lyapunov Structures ...

By: J. D. Keller; A. Hense

Description: Hans-Ertel-Centre for Weather Research, Bonn, Germany. We present a new approach to estimate local Lyapunov vectors. The so called self-breeding method is based on the breeding of growing modes technique from medium range weather forecasting and consists of a continuous forecasting and rescaling cycle. Using the Lorenz96 model we test and characterize the behavior of the algorithm regarding error growth, spatial perturbation structure estimates and...

Lorenz, E. N.: Predictability: a problem partly solved, in: Proceedings of the Seminar on Predictability, vol. 1, 1–18, ECMWF, Reading, UK, 1995.; Kalnay, E., Corazza, M., and Cai, M.: Are bred vectors the same as Lyapunov vectors?, in: AMS Symposium on Observations, Data Assimilation and Probabilistic Prediction, Orlando, FL, USA, 173–177, 2002.; Legras, B. and Vautard, R.: A guide to Liapunov vectors, in: Proceedings of the Seminar on Predictability, vol. 1, ECMWF, Rea...

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Long Solitary Internal Waves in Stable Stratifications : Volume 11...

By: J. M. Rees; W. B. Zimmerman

Description: Department of Chemical and Process Engineering, University of Sheffield, Sheffield S1 3JD, UK. Observations of internal solitary waves over an antarctic ice shelf (Rees and Rottman, 1994) demonstrate that even large amplitude disturbances have wavelengths that are bounded by simple heuristic arguments following from the Scorer parameter based on linear theory for wave trapping. Classical weak nonlinear theories that have been applied to stable stratific...

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Loading Rates in California Inferred from Aftershocks : Volume 15,...

By: P. Shebalin; M. Holschneider; C. Narteau

Description: Laboratoire de Dynamique des Fluides Géologiques, Institut de Physique du Globe de Paris, 75252 Paris Cedex 05, France. We estimate the loading rate in southern California and the change in stress induced by a transient slip event across the San Andreas fault (SAF) system in central California, using a model of static fatigue. We analyze temporal properties of aftershocks in order to determine the time delay before the onset of the power law aftershoc...

Argus, D. and Gordon, R.: Present tectonic motion across the Coast Ranges and San Andreas fault system in central California, Geol. Soc. Am. Bull., 113, 1580–1592, 2001.; Atkinson, B K.: Subcritical crack growth in geological materials, J. Geophys. Res., 89, 4077–4114, 1984.; Atkinson, B K. and Meredith, P G.: The theory of subcritical crack growth with applications to minerals and rocks, in: Fracture Mechanics of rock, edited by Atkinson, B K., Geology series, 111–166, ...

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Time-scale Invariant Changes in Atmospheric Radon Concentration an...

By: Y. Yasuoka; Y. Omori; T. Ishikawa; H. Nagahama; Y. Kawada; S. Tokonami; M. Shinogi

Description: Department of Geoenvironmental Sciences, Graduate School of Science, Tohoku University, Sendai, Japan. Prior to large earthquakes (e.g. 1995 Kobe earthquake, Japan), an increase in the atmospheric radon concentration is observed, and this increase in the rate follows a power-law of the time-to-earthquake (time-to-failure). This phenomenon corresponds to the increase in the radon migration in crust and the exhalation into atmosphere. An irreversible therm...

Ball, T. K., Cameron, D. G., Colman, T. B., and Roberts, P. D.: Behaviour of radon in the geological environment: a review, Quart. J. Engng. Geol., 24, 169–182, 1991.; Bear, J.: Dynamics of Fluids in Porous Media, Elsevier, New York, 1972.; Biot, M. A.: General theory of three-dimensional consolidation, J. Appl. Phys., 12, 155–164, 1941.; Ben-Zion, Y. and Lyakhovsky, V.: Accelerated seismic release and related aspects of seismicity patterns on earthquake faults, Pure App...

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New Significance Test Methods for Fourier Analysis of Geophysical ...

By: J. Moore; Z. Zhang

Description: College of Global Change and Earth System Science, Beijing Normal University, China. When one applies the discrete Fourier transform to analyze finite-length time series, discontinuities at the data boundaries will distort its Fourier power spectrum. In this paper, based on a rigid statistics framework, we present a new significance test method which can extract the intrinsic feature of a geophysical time series very well. We show the difference in sign...

Baldwin, M. P. and T. J. Dunkerton, Stratospheric harbingers of anomalous weather regimes, Science, 294, 581–584, 2001.; Brockwell, P. J. and Davis, R. A., Time series: Theory and Methods, Springer-Verlag, New York, 1991.; Chatfield, C.: The Analysis of Time Series: An Introduction, 4th Edn., Chapman and Hall, 1989.; Gilman, D. L., Fuglister, F. J., and Mitchell Jr., J. M.: On the power spectrum of red noise, J. Atmos. Sci., 20, 182–184, 1963.; Ghil, M., Allen, M. R., De...

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Increasing the Horizontal Resolution of Ensemble Forecasts at Cmc ...

By: C. Girard; L. Lefaivre; P. Houtekamer; G. Pellerin

Description: Canadian Meteorological Centre, Montreal, Canada. Ensemble forecasts are run operationally since February 1998 at the Canadian Meteorological Centre, with outputs up to ten days. The ensemble size was increased from eight to sixteen members in August 1999. The method of producing the perturbed analyses consists of running independent assimilation cycles that use perturbed sets of observations and are driven by eight different models, ...

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Long's Equation in Terrain Following Coordinates : Volume 16, Issu...

By: M. Humi

Description: Department of Mathematical Sciences, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA. Long's equation describes two dimensional stratified atmospheric flow over terrain which is represented by the geometry of the domain. The solutions of this equation over simple topography were investigated analytically and numerically by many authors. In this paper we derive a new terrain following formulation of this equation which incorp...

Baines, P. G.: Topographic effects in Stratified flows, Cambridge Univ.\ Press, New-York, 1995.; Nappo, C. J.: Atmospheric Gravity Waves, Academic Press, Boston, 2002.; Davis, K. S.: Flow of Nonuniformly Stratified Fluid of Large Depth over Topography, M.Sc. thesis in Mechanical Engineering, MIT, Cambridge, MA, 1999.; Dewan, E. M., Picard, R. H., O'Neil, R. R., Gardiner, H. A., Gibson, J., Mill, J. D., Richards, E., Kendra, M., and Gallery, W. O.: MSX satellite observati...

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Contraction of Westward-travelling Nonlocal Modons Due to the Vort...

By: Z. Kizner; D. Berson

Description: Department of Physics, Bar-Ilan University, Ramat-Gan 52900, Israel. Long-term evolution of westward-travelling non-local modons on the β-plane, i.e. dipolar vortices imbedded in slowly damping Rossby wave fields, is studied numerically. In the framework of the nondivergent (barotropic) model, two stages of the evolution are observed. At the first stage (for about 30 synoptic periods), the parameters and the form of the vortex ...

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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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Direct and Inverse Cascades in the Geodynamo : Volume 15, Issue 6 ...

By: P. Hejda; M. Reshetnyak

Description: Institute of the Physics of the Earth, Russian Acad. Sci, 123995 Moscow, Russia. The rapid rotation of planets causes cyclonic thermal turbulence in their cores which may generate the large-scale magnetic fields observed outside the planets. We investigate numerically a model based on the geodynamo equations in simplified geometry, which enables us to reproduce the main features of small-scale geostrophic flows in physical and wave vector spaces. ...

Alexakis, A., Mininni, P. D., and Pouquet, A.: Turbulent cascades, transefer, and scale interactions in magentohydrodynamics, New J. Phys., 9, 1–20, 2007.; Batchelor, G. K.: The theory of homogeneous turbulence, Cambridge University Press, Cambridge, 1953.; Buffett, B.: A comparison of subgrid-scale models for large-eddy simulations of convection in the Earth's core, Geophys. J. Int., 153, 753–765, 2003.; Busse, F. H.: Thermal instabilities in rapidly rotating systems, J...

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Generation of Weakly Nonlinear Nonhydrostatic Internal Tides Ove...

By: T. Gerkema; R. Maugé

Description: Laboratoire de Physique des Océans, Université de Bretagne Occidentale, 6 avenue Le Gorgeu, 29238 Brest, France. A set of evolution equations is derived for the modal coefficients in a weakly nonlinear nonhydrostatic internal-tide generation problem. The equations allow for the presence of large-amplitude topography, e.g. a continental slope, which is formally assumed to have a length scale much larger than that of the internal tide. However, comparison ...

Akylas, T R., Grimshaw, R. H J., Clarke, S R., and Tabaei, A.: Reflecting tidal wave beams and local generation of solitary waves in the ocean thermocline, J. Fluid Mech., 593, 297–313, 2007.; Bender, C M. and Orszag, S A.: Advanced mathematical methods for scientists and engineers, McGraw-Hill, 1978.; Durran, D R.: Numerical methods for wave equations in geophysical fluid dynamics, Springer, 1999.; Garrett, C. and Gerkema, T.: On the body-force term in internal-tide gen...

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Passive Tracer Patchiness and Particle Trajectory Stability in Inc...

By: M. G. Brown; M. J. Olascoaga; F. J. Beron-vera

Description: RSMAS, University of Miami, Miami, Florida, USA. Particle motion is considered in incompressible two-dimensional flows consisting of a steady background gyre on which an unsteady wave-like perturbation is superimposed. A dynamical systems point of view that exploits the action-angle formalism is adopted. It is argued and demonstrated numerically that for a large class of problems one expects to observe a mixed phase space, i.e. the occurrence of regula...

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Fem and Ann Combined Approach for Predicting Pressure Source Param...

By: G. Currenti; C. Del Negro; L. Fortuna; G. Nunnari; A. Di Stefano

Description: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Catania, Italy. A hybrid approach for forward and inverse geophysical modeling, based on Artificial Neural Networks (ANN) and Finite Element Method (FEM), is proposed in order to properly identify the parameters of volcanic pressure sources from geophysical observations at ground surface. The neural network is trained and tested with a set of patterns obtained by the solutions of numerical model...

Aagaard, B., Kientz, S., Knepley, M., Strand, L., and Williams, C.: PyLith User Manual, Version 1.3, Computational Infrastructure for Geodynamics, www.geodynamics.org/cig/software/short/pylith/pylith_book-1.3.pdf (last access: October 2009), 2008; Ajmera, T. and Rastogi, A. K.: Artificial Neural Network Application on Estimation of Aquifer Transmissivity, JoSH, 8(2), 15–31, 2008.; Arena, P., Fo...

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The Role of Subsidence in a Weakly Unstable Marine Boundary Layer:...

By: M. Cassol; U. Rizza; M. M. Miglietta; A. S. Lanotte; A. M. Sempreviva; I. M. Mazzitelli

Description: Dip. Ingegneria dell'Innovazione, Univ. del Salento, 73100 Lecce, Italy. The diurnal evolution of a cloud free, marine boundary layer is studied by means of experimental measurements and numerical simulations. Experimental data belong to an investigation of the mixing height over inner Danish waters. The mixed-layer height measured over the sea is generally nearly constant, and does not exhibit the diurnal cycle characteristic of boundary layers over la...

Batcharova, E. and Gryning, S.-E.: Applied model for the growth of the daytime mixed layer, Bound.-Lay. Meteorol., 56, 261–274, 1991.; Batcharova, E. and Gryning, S.-E.: Applied model for the height of the daytime mixed layer and the entrainment zone, Bound.-Lay. Meteorol., 71, 311–323, 1994.; Bellon, G. and Stevens, B.: Using the Sensitivity of Large-Eddy Simulations to Evaluate Atmospheric Boundary Layer Models, J. Atmos. Sci., 69, 1582–1601, 2012.; Carlson, M. A. and ...

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Nonlinear Electron Acoustic Structures Generated on the High-poten...

By: M. Berthomier; R. Pottelette

Description: LPP-CNRS/INSU, 4 avenue de Neptune, 94107 Saint-Maur des Fossés, France. High-time resolution measurements of the electron distribution function performed in the auroral upward current region reveals a large asymmetry between the low- and high-potential sides of a double-layer. The latter side is characterized by a large enhancement of a locally trapped electron population which corresponds to a significant part (~up to 30%) of the total electron density. ...

Bale, S. D., Hull, A., Larson, D. E., Lin, R. P., Muschietti, L., Kellogg, P. J., Goetz, K., and Monson, S. J. : Electrostatic turbulence and Debye-scale structures associated with electron thermalization at collisionless shocks, Astrophys. J., 575, L25–L28, 2002.; Berthomier, M., Pottelette, R., Malingre, M., and Khotyaintsev, Y.: Electron-acoustic solitons in an electron-beam plasma system, Phys. Plasmas, 9, 2987–2994, 2000.; Carlson, C. W., Pfaff, R., and Watzin, J. G...

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Estimation of the Total Magnetization Direction of Approximately S...

By: V. C. F. Barbosa; D. P. Sales; V. C. Oliveira Jr.; L. Uieda

Description: Observatório Nacional, Rio de Janeiro, Brazil. We have developed a fast total-field anomaly inversion to estimate the magnetization direction of multiple sources with approximately spherical shape and known centres. Our method can be applied to interpret multiple sources with different magnetization directions. It neither requires the prior computation of any transformation like reduction to the pole nor the use of regularly spaced data on a hori...

Almeida, F. F. M.: Relações tectônicas das rochas alcalinas mesozóicas da região meridional da plataforma sul-americana, Revista Brasileira de Geociências, 13, 139–158, 1983.; Aster, R. C., Borchers, B., and Thurber, C. H.: Parameter Estimation and Inverse Problems (International Geophysics), Academic Press, San Diego, USA, 2005.; Baranov, V.: A new method for interpretation of aeromagnetic maps: pseudo-gravimetric anomalies, Geophysics, 22, 359–382,

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Temporal Variations of the Fractal Properties of Seismicity in the...

By: I. Main; Ö. Alptekin; A. O. Öncel

Description: Department of Geophysical Engineering, Division of Seismology, Istanbul University, 34850 Avcilar, Instanbul, Turkey. Seismically-active fault zones are complex natural systems exhibiting scale-invariant or fractal correlation between earthquakes in space and time, and a power-law scaling of fault length or earthquake source dimension consistent with the exponent b of the Gutenberg-Richter frequency-magnitude relation. The fractal dimension of seismicity...

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Asymmetric Multifractal Model for Solar Wind Intermittent Turbulen...

By: W. M. MacEk; A. Szczepaniak

Description: Space Research Centre, Polish Academy of Science, Bartycka 18A, 00-716 Warsaw, Poland. We consider nonuniform energy transfer rate for solar wind turbulence depending on the solar cycle activity. To achieve this purpose we determine the generalized dimensions and singularity spectra for the experimental data of the solar wind measured in situ by Advanced Composition Explorer spacecraft during solar maximum (2001) and minimum (2006) at 1 AU. By determin...

Marsch, E. and Tu, C.-Y.: Intermittency, non-Gaussian statistics and fractal scaling of MHD fluctuations in the solar wind, Nonlin. Processes Geophys., 4, 101–124, 1997.; Marsch, E., Tu, C.-Y., and Rosenbauer, H.: Multifractal scaling of the kinetic energy flux in solar wind turbulence, Ann. Geophys., 14, 259–269, 1996.; Meneveau, C. and Sreenivasan, K. R.: Simple multifractal cascade model for fully developed turbulence, Phys. Rev. Lett., 59, 1424–1427, 1987.; Meneveau,...

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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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Earthquake Forecasting Based on Data Assimilation: Sequential Mont...

By: M. J. Werner; K. Ide; D. Sornette

Description: Swiss Seismological Service, Institute of Geophysics, ETH Zurich, Switzerland. Data assimilation is routinely employed in meteorology, engineering and computer sciences to optimally combine noisy observations with prior model information for obtaining better estimates of a state, and thus better forecasts, than achieved by ignoring data uncertainties. Earthquake forecasting, too, suffers from measurement errors and partial model information and may thus...

Zechar, J. D., Schorlemmer, D., Liukis, M., Yu, J., Euchner, F., Maechling, P. J., and Jordan, T. H.: The {C}ollaboratory for the {S}tudy of {E}arthquake {P}redictability perspective on computational earthquake science, Concurrency and Computation: Practice and Experience, 22(12), 1836–1847, doi:10.1002/cpe.1519, 2010.; Andrieu, C., Doucet, A., Singh, S., and Tadic, V.: Particle methods for change detection, system identific...

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