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Astronomy


Astronomy is a natural science that deals with the study of celestial objects (such as stars, planets, comets, nebulae, star clusters and galaxies) and phenomena that originate outside the Earth's atmosphere (such as the cosmic background radiation). It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the formation and development of the universe.

 
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Quantifying the Impact of Groundwater Depth on Evapotranspiration ...

By: T. Wang; J. D. Lenters; M. E. Soylu; E. Istanbulluoglu

Description: University of Nebraska-Lincoln, School of Natural Resources, Lincoln, Nebraska, USA. The interactions between shallow groundwater and land surface processes, mediated by capillary rise processes from groundwater, may play an important role in the ecohydrology of riparian zones in both humid and semi-arid ecosystems. Some recent land surface models (LSM) incorporate the contribution of groundwater to land surface processes with varying levels of complexi...

Allen, M. B. and Murphy, C. L.: A Finite-Element Collocation Method for Variably Saturated Flow in Two Space Dimensions, Water Resour. Res., 22, 1537–1542, doi:10.1029/WR022i011p01537, 1986.; Anat, A., Duke, H. R., and Corey, A. T.: Steady upward flow from water table, Hydrol. Pap. 7, Colo. State Univ., Fort Collins, 1965.; Bogaart, P. W., Teuling, A. J., and Troch, P. A.: A state-dependent parameterization of saturated-unsaturated zone interaction, Water Resour. Res., 4...

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Willy Stoffregen – an Early Pioneer of Advanced Ionospheric and Au...

By: K. Schlegel; H. Lühr

Description: Copernicus Gesellschaft, Göttingen, Germany. We sketch the eventful life of Willy Stoffregen and summarise his engineering and scientific achievements.

We did not attempt to list all publications of Stoffregen. In addition to the contributions cited here, he published numerous internal reports at the Uppsala Ionospheric Observatory.; ; Appleton, E. V. and Naismith, R.: Scattering of radio waves in polar regions, Nature, 143, 243–244, 1939.; Boström, R. and Stoffregen, W: Implementation of Ground-Based Facilities to Study the Ionosphere and Magnetosphere above Scandinavia and their Role in Sounding Rocket Experiments, Fi...

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Investigations of the Auroral Luminosity Distribution and the Dyna...

By: V. L. Zverev; M. Förster; Y. I. Feldstein; V. G. Vorobjev

Description: Institute of Terrestrial Magnetism, Ionosphere, and Radiowave Propagation of the Russian Academy of Sciences (IZMIRAN), 142090 Troitsk, Moscow region, Russia. Research results about planetary-scale auroral distributions are presented in a historical retrospective, beginning with the first maps of isochasms – lines of equal visibility of auroras in the firmament (Fig. 2) – up to isoaurora maps – lines of equal occurrence frequency of auroras in the zenith...

Akasofu, S.-I., The dynamical morphology of the aurora polaris, J. Geophys. Res., 68, 1667–1673, 1963.; Ackerson, K. L. and L. A. Frank, Correlated satellite measurements of low-energy electron precipitation and ground-based observations of a visibly auroral arc, J. Geophys. Res., 77, 1128–1136, 1972.; Akasofu, S.-I.: The development of the auroral substorm, Planet. Space Sci., 12, 273–282, 1964a.; Akasofu, S.-I.: The latitudinal shift of the auroral belt, J. Atmos. Terr...

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Magnetic Storm Free Ulf Analysis in Relation with Earthquakes in T...

By: T.-k. Yeh; H.-y. Yen; K. Hattori; T.-c. Shin; C.-h. Chen; H. Peng; J.-y. Liu; S. Wen; C.-h. Wang

Description: Institute of Seismology, National Chung Cheng University, Chiayi 621, Taiwan. Despite early optimism, pre-earthquake anomalous phenomena can be determined by using enhanced amplitude at the ultra-low-frequency range from geomagnetic data via the Fourier transform. In reality, accuracy of the enhanced amplitude in relation to earthquakes (deduced from time-varied geomagnetic data) would be damaged by magnetic storms and/or other unwanted influences resul...

Bernardi, A., Fraser-Smith, A. C., McGill, P. R., and Villard Jr., O. G.: ULF magnetic field measurements near the epicenter of the Ms 7.1 Loma Prieta earthquake, Phys. Earth Planet. Int., 68, 45–63, 1991.; Bliokh, P. V., Nickolaenko, A. P., Filippov, and Yu. F.: Schumann Resonances in the Earth-ionosphere Cavity, Peter Peregrinus Ltd., Stevenage, UK, 1980.; Chapman, S. and Bartels, J.: Geomagnetism, Vol. I: Geomagnetic and Related Phenomena, Vol. II: Analysis of Data an...

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Multiscale Entropy Analysis of Electroseismic Time Series : Volume...

By: F. Angulo-brown; A. Ramírez-rojas; L. Guzmán-vargas

Description: Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas, Instituto Politécnico Nacional, Av. IPN No. 2580, Col. Ticomán, México D. F. 07340, Mexico. In this work we use the multiscale entropy method to analyse the variability of geo-electric time series monitored in two sites located in Mexico. In our analysis we consider a period of time from January 1995 to December 1995. We systematically calculate the sample entropy of electroseism...

Hayakawa, M. (Ed.): Atmospheric and Ionospheric Phenomena Associated with Earthquakes, Terra Sc. Publ. Tokyo, 996 pp., 1999.; Costa, M., Goldberger, A. L., and Peng, C.-P.: Multiscale entropy analysis of physiologic time series, Phys. Rev. Lett., 89, 068102, 2002.; Costa, M., Goldberger, A. L., and Peng, C.-K.: Multiscale entropy analysis of biological signals, Phys. Rev. E., 71, 021906, 2005.; Eckmann, J.-P. and Ruelle, D.: Ergodic theory of chaos and strange atractors,...

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Synchronicity in Predictive Modelling: a New View of Data Assimila...

By: J. J. Tribbia; J. B. Weiss; G. S. Duane

Description: National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307, USA. The problem of data assimilation can be viewed as one of synchronizing two dynamical systems, one representing truth and the other representing model, with a unidirectional flow of information between the two. Synchronization of truth and model defines a general view of data assimilation, as machine perception, that is reminiscent of the Jung-Pauli notion of synchronicity be...

Afraimovich, V. S., Verichev, N. N., and Rabinovich, M. I.: Stochastic synchronization of oscillation in dissipative systems, Radiophys. Quantum Electron., 29, 795–803, 1986.; Anderson, J. L.: An ensemble adjustment Kalman filter for data assimilation, Mon. Wea. Rev., 129, 2884–2903, 2001.; Anderson, J. L.: A local least-squares framework for ensemble filtering, Mon. Wea. Rev., 131, 634–642, 2003.; Corazza, M., Kalnay, E., Patil, D. J., Yang, S.-C., Morss, R., Cai, M., S...

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Detecting Unstable Structures and Controlling Error Growth by Assi...

By: F. Uboldi; A. Trevisan

Description: no current affiliation. Oceanic and atmospheric prediction is based on cyclic analysis-forecast systems that assimilate new observations as they become available. In such observationally forced systems, errors amplify depending on their components along the unstable directions; these can be estimated by Breeding on the Data Assimilation System (BDAS). Assimilation in the Unstable Subspace (AUS) uses the available observations to estimate the amplitude ...

Brasseur, P., Ballabrera-Poy, J., and Verron, J.: Assimilation of altimetric data in the mid-latitude oceans using the Singular Evolutive Extended Kalman Filter with an eddy-resolving, primitive equation model, J. Mar. Syst., 22, 269-294, 1999.; Evensen, G.: Sampling strategies and square root analysis schemes for EnKF, Ocean Dynamics, 54, 539-560, 2004.; Bennett, A F.: Inverse methods in physical oceanography, Cambridge University Press, 1992.; Bennett, A F.: Inverse Mo...

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A Case for Variational Geomagnetic Data Assimilation: Insights fro...

By: T. Alboussière; C. Eymin; A. Fournier

Description: Laboratoire de Géophysique Interne et Tectonophysique, Université Joseph-Fourier, BP 53, 38041 Grenoble cedex 9, France. Secular variations of the geomagnetic field have been measured with a continuously improving accuracy during the last few hundred years, culminating nowadays with satellite data. It is however well known that the dynamics of the magnetic field is linked to that of the velocity field in the core and any attempt to model secular variatio...

Amit, H. and Olson, P.: Helical core flow from geomagnetic secular variation, Phys. Earth Planet. Inter., 147, 1–25, \doi10.1016/j.pepi.2004.02.006, 2004.; Anderson, E., Bai, Z., Bischof, C., Blackford, S., Demmel, J., Dongarra, J., Du~Croz, J., Greenbaum, A., Hammarling, S., McKenney, A., and Sorensen, D.: LAPACK Users' Guide, Society for Industrial and Applied Mathematics, Philadelphia, PA, third edn., 1999.; Backus, G E.: Kinematics of geomagnetic secular variation in...

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Climate of Utopia : Volume 15, Issue 4 (07/07/2008)

By: M. Gedalin; M. Balikhin

Description: Department of Physics, Ben-Gurion University, Beer-Sheva, Israel. Climate is usually considered to depend on a large number of parameters, this being essentially a functional in multi-dimensional parameter space. We propose a low-dimensional model of a climate where the temperature field on a thermally conducting planet depends on the external energy input and very limited number of internal parameters, like thermal conductivity and reflectivity. Equili...

Alley, R. B., Marotzke, J., Nordhauset, W. D., et al.: Abrupt climate change, Science, 299, 2005–2010, 2003.; Boer, G. J., Hamilton, K., and Zhu, W., Climate sensitivity and climate change under strong forcing, Clim. Dynam., 24, 685–700, 2005.; Braun, H., Christl, M., Rahmstorf, S., et al.: Possible solar origin of the 1,470-year glacial climate cycle demonstrated in a coupled model, Nature, 438, 208–211, 2005.; Braun, H., Ganopolski, A., Christl, M., and Chialvo, D. R.:...

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Extreme Event Return Times in Long-term Memory Processes Near 1/F ...

By: K. Fraedrich; F. Sienz; R. Blender

Description: Universität Hamburg, Meteorologisches Institut, Bundesstrasse 55, 20146 Hamburg, Germany. The distribution of extreme event return times and their correlations are analyzed in observed and simulated long-term memory (LTM) time series with 1/f power spectra. The analysis is based on tropical temperature and mixing ratio (specific humidity) time series from TOGA COARE with 1 min resolution and an approximate 1/f power spectrum. Extreme event...

%Kuznetsov, E. A., Passot, T., and Sulem, P. L.: A dynamical model %for nonlinear mirror modes near threshold, Phys. Rev. Lett., 98, %235003(1�4), 2007.; Abaimov, S. G., Turcotte, D. L., Shcherbakov, R., and Rundle, J. B.,: Recurrence and interoccurrence behavior of self-organized complex phenomena, Nonlin. Processes Geophys., 14, 455–464, 2007.; Altmann, E. G. and Kantz, H.: Recurrence time analysis, long-term correlations, and extreme events, Phys. Rev. E, 71, 056106, ...

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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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Convex and Concave Types of Second Baroclinic Mode Internal Solita...

By: Y. C. Fang; T. Y. Tang; S. R. Ramp; Y. J. Yang

Description: Department of Marine Science, Naval Academy, Kaohsiung, Taiwan. Two types of second baroclinic mode (mode-2) internal solitary waves (ISWs) were found on the continental slope of the northern South China Sea. The convex waveform displaced the thermal structure upward in the upper layer and downward in the lower layer, causing a bulge in the thermocline. The concave waveform did the opposite, causing a constriction. A few concave waves were observed in t...

Gill, A. E.: Atmosphere-Ocean Dynamics, Academic Press, San Diego, 662 pp., 1982; Grimshaw, R.: Evolution equations for long nonlinear waves in stratified shear flow, Stud. Appl. Math., 65, 159–188, 1981.; Gear, J. and Grimshaw, R.: A second-order theory for solitary waves in shallow fluids, Phys. Fluids, 26, 14–29, 1983.; Akylas, T. and Grimshaw, R.: Solitary internal waves with oscillatory tails, J. Fluid Mech., 242, 279–298, 1992.; Alpers, W.: Theory of radar imaging ...

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Non-diffusive, Non-local Transport in Fluids and Plasmas : Volume ...

By: D. Del-castillo-negrete

Description: Oak Ridge National Laboratory, Oak Ridge, TN, USA. A review of non-diffusive transport in fluids and plasmas is presented. In the fluid context, non-diffusive chaotic transport by Rossby waves in zonal flows is studied following a Lagrangian approach. In the plasma physics context the problem of interest is test particle transport in pressure-gradient-driven plasma turbulence. In both systems the probability density function (PDF) of particle displaceme...

Bouchaud, J. P. and Georges, A.: , Phys. Rep., 195, p. 127, doi:10.1016/0370-1573(90)90099-N, 1990.; Callen, J. D. and Kissick, M. W.: , Plasma Phys. Contr. F., 39, B173, doi:10.1088/0741-3335/39/12B/014, 1997.; Carreras, B. A., Garcia, L., and Diamond, P. H.: , Phys. Fluids, 30, 1388, doi:10.1063/1.866518, 1987.; Cartea, A. and del-Castillo-Negrete, D.: , Phys. Rev. E, 76, 041105, doi:10.1103/PhysRevE.76.041105, 2007.; del-Castillo-Negrete, D.: , Phys. Fluids, 10, p. 57...

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Predictability of Extreme Values in Geophysical Models : Volume 19...

By: P. Rabassa; H. W. Broer; M. P. Holland; A. E. Sterk; R. Vitolo

Description: College of Engineering, Mathematics and Physical Sciences, Harrison Building, Streatham Campus, University of Exeter, North Park Road, Exeter, EX4 4QF, UK. Extreme value theory in deterministic systems is concerned with unlikely large (or small) values of an observable evaluated along evolutions of the system. In this paper we study the finite-time predictability of extreme values, such as convection, energy, and wind speeds, in three geophysical models. ...

Abarbanel, H., Brown, R., and Kennel, M.: Variation of {L}yapunov Exponents on a Strange Attractor, J. Nonlin. Sci., 1, 175–199, 1991.; Bailey, B., Ellner, S., and Nychka, D.: Chaos with confidence: asymptotics and applications of local {L}yapunov exponents, Fields Institute Communications, 11, 115–133, 1997.; Beirlant, J., Goegebeur, Y., Teugels, J., and Segers, J.: Statistics of Extremes: Theory and Applications, John Wiley and Sons, Berlin, 2004.; Bowler, N., Arribas,...

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The Rossby Wave Extra Invariant in the Dynamics of 3-d Fluid Layer...

By: A. M. Balk

Description: Department of Mathematics, University of Utah, Salt Lake City, UT 84112, USA. We consider an adiabatic-type (approximate) invariant that was earlier obtained for the quasi-geostrophic equation and the shallow water system; it is an extra invariant, in addition to the standard ones (energy, enstrophy, momentum), and it is based on the Rossby waves. The presence of this invariant implies the energy transfer from small-scale eddies to large-scale zonal jet...

Balk, A. M., Nazarenko, S. V., and Zakharov, V. E.: New invariant for drift turbulence, Phys. Lett. A, 152, 276–280, 1991.; Balk, A. M.: A new invariant for Rossby wave systems, Phys. Lett. A, 155, 20–24, 1991.; Balk, A. M.: New conservation laws for the interaction of nonlinear waves, SIAM Rev., 39, 68–94, 1997.; Balk, A. M.: Angular distribution of Rossby wave energy, Phys. Lett. A, 345, 154–160, 2005.; Balk, A. M. and Ferapontov, E. V.: Invariants of 4-wave interactio...

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Data Assimilation Experiments Using the Diffusive Back and Forth N...

By: D. Auroux; G. A. Ruggiero; J. Blum; E. Cosme; J. Verron; Y. Ourmières

Description: Université de Nice Sophia-Antipolis/LJAD, Nice, France. The Diffusive Back and Forth Nudging (DBFN) is an easy-to-implement iterative data assimilation method based on the well-known Nudging method. It consists in a sequence of forward and backward model integrations, within a given time window, both of them using a feedback term to the observations. Therefore in the DBFN, the Nudging asymptotic behavior is translated into an infinite number of i...

Anderson, J. L.: A local least squares framework for ensemble filtering, Mon. Weather Rev., 131, 634–642, 2003.; Abarbanel, H. D. I., Kostuk, M., and Whartenby, W.: Data assimilation with regularized nonlinear instabilities, Q. J. Roy. Meteorol. Soc., 136, 769–783, doi:10.1002/qj.600, 2010.; Anthes, R. A.: Data assimilation and initialization of hurricane prediction models, J. Atmos. Sci., 31, 702–719,

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A Method to Calculate Finite-time Lyapunov Exponents for Inertial ...

By: D. Garaboa; V. Pérez-muñuzuri

Description: Group of Nonlinear Physics, Faculty of Physics, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain. The present study aims to improve the calculus of Finite-Time Lyapunov Exponents (iFTLEs) applied to describe the transport of inertial particles in a fluid flow. To this aim, the deformation tensor used to obtain the iFTLE is modified to take into account that the stretching rate between particles separated by a certain ...

Babiano, A., Cartwright, H. H. E., Piro, O., and Provenzale, A. Dynamics of a small neutrally buoyant sphere in a fluid and targeting in Hamiltonian systems, Phys. Rev. Lett., 84, 5764–5767, 2000.; Bec, J.: Fractal clustering of inertial particles in random flows, Phys. Fluids 15, L81–L84, 2003.; Beron-Vera, F. J., Olascoaga, M. J., Haller, G., Farazmand, M., Triñanes, J., and Wang, Y.: Dissipative inertial transport patterns near coherent Lagrangian eddies in the ocean,...

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On the Indonesian Throughflow in the Occam 1/4 Degree Ocean Model ...

By: U. W. Humphries; D. J. Webb

Description: King Monghut's Institute of Technology, Thailand. The Indonesian Throughflow is analysed in two runs of the OCCAM 1/4 degree global ocean model, one using monthly climatological winds and one using ECMWF analysed six-hourly winds for the period 1993 to 1998. The long-term model throughflow agrees with observations and the value predicted by Godfrey's Island Rule. The Island Rule has some skill in predicting the annual signal each year but is poor at pre...

Arief, D. and Murray, S. P: Low-frequency fluctuations in the Indonesian Throughflow through Lombok Strait, J. Geophys. Res., 101(C5), 12 455–12 464, 1996.; Arakawa, A.: Computational design for long-term numerical integration of the equations of fluid motion: Two-dimensional incompressible flow, J. Comput. Phys., 1, 119–143, 1966.; Armi, L. and Williams, R.: The hydraulics of a stratified fluid flowing through a contraction, J. Fluid Mech., 251, 355–375, 1993.; Bryan, K...

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On the Time to Tracer Equilibrium in the Global Ocean : Volume 5, ...

By: E. Deleersnijder; F. Primeau

Description: Department of Earth System Science, University of California at Irvine, Rowland Hall, Irvine, CA 92697, USA. An important issue for the interpretation of data from deep-sea cores is the time for tracers to be transported from the sea surface to the deep ocean. Global ocean circulation models can help shed light on the timescales over which a tracer comes to equilibrium in different regions of the ocean. In this note, we discuss how the most slowly ...

Broecker, W. S. and Peng, T.-H.: Tracers in the sea, Lamont-Doherty Geological Observatory, Palisades, NY., 690 pp., 1982.; Campin, J.-M., Fichefet, T., and Duplessy, J.-C.: Problems with using radiocarbon to infer ocean ventilation rates for past and present climates, Earth Planet. Sci. Lett., 165, 17–24, 1999.; Cox, M. D.: An Idealized Model of the World Ocean. Part I: The Global-Scale Water Masses., J. Phys. Oceanogr. 19, 1730–1752, 1989.; Delhez, E. J. M., Campin, J....

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Estimates of Radiance Reflected Towards the Zenith at the Surface ...

By: E. Aas

Description: Department of Geosciences, University of Oslo, Norway. Remote sensing of water colour by ship-mounted sensors represents an important tool for the validation of satellite products and the monitoring of water quality. The recorded radiance from the sea has to be corrected for the surface-reflected radiance from sun and sky in order to obtain the water-leaving radiance. Here the simple case of radiance reflected towards the zenith is studied. A set of obs...

Aas, E.: Calibration of a marine radiance and colour index meter, Rep. No. 87, Dept. Geophys., Univ. Oslo, 1993.; Aas, E. and Høkedal, J.: Reflection of spectral sky irradiance on the surface of the sea and related properties, Remote Sens. Environ., 70, 181–190, 1999.; Aas, E. and Højerslev, N. K.: Analysis of underwater radiance observations: Apparent optical properties and analytic functions describing the angular radiance distribution, J. Geophys. Res., 104, 8015–8024...

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