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Sample records for earth magnetosphere

  1. Global MHD model of the earth's magnetosphere

    Science.gov (United States)

    Wu, C. C.

    1983-01-01

    A global MHD model of the earth's magnetosphere is defined. An introduction to numerical methods for solving the MHD equations is given with emphasis on the shock-capturing technique. Finally, results concerning the shape of the magnetosphere and the plasma flows inside the magnetosphere are presented.

  2. Magnetic Reconnection in the Earth's Magnetosphere

    Science.gov (United States)

    Tsurutani, B. T.; Lakhina, G. S.

    1997-01-01

    The process of magnetic reconnection plays an important role during the interaction of the solar wind with the Earth's magnetosphere which leads to the exchange of mass, momentum, and energy between these two highly conducting plasmas.

  3. An MHD model of the earth's magnetosphere

    Science.gov (United States)

    Wu, C. C.

    1985-01-01

    It is pointed out that the earth's magnetosphere arises from the interaction of the solar wind with the earth's geomagnetic field. A global magnetohydrodynamics (MHD) model of the earth's magnetosphere has drawn much attention in recent years. In this model, MHD equations are used to describe the solar wind interaction with the magnetosphere. In the present paper, some numerical aspects of the model are considered. Attention is given to the ideal MHD equations, an equation of state for the plasma, the model as an initial- and boundary-value problem, the shock capturing technique, computational requirements and techniques for global MHD modeling, a three-dimensional mesh system employed in the global MHD model, and some computational results.

  4. Multiscale phenomena in the Earth's Magnetosphere

    Science.gov (United States)

    Surjalal Sharma, A.

    The multiscale phenomena in the Earth's magnetosphere have been studied using data from ground-based and space-borne measurements. The ground-based observations provide data over decades and are suitable for characterizing the inherent nature of the multiscale behavior and for studying the dynamical and statistical features. On the other hand, the spacecraft data provide in-situ observations of the processes. The multipoint measurements by Cluster have provided a new understanding of the plasma processes at microand meso-scales and the cross-scale coupling among them. The role of cross-scale coupling is evident in phenomena such as bursty bulk flows, flux ropes, and reconnection. The characteristic scales of the processes range from electron skin depth to MHD scales and the modeling of these processes need different physical models, such as kinetic, EMHD, Hall MHD, and MHD. The ground-based data have been used to develop models based on techniques of nonlinear science and yield predictive models which can be used for forecasting. These models characterize the magnetospheric dynaics and yield its global and multiscale aspects. The distribution of scales in the magnetosphere is studied using an extensive database of the solar wind and the magnetosphere. The distributions of the waiting times deviate significantly from a power law as well as stretched exponential distributions, and show a scaling with respect to the mean, indicating a limited role of long-term correlations in the magnetospheric dynamics.

  5. Global ENA Imaging of Earth's Dynamic Magnetosphere

    Science.gov (United States)

    Brandt, Pontus

    2015-04-01

    The interaction between singly charged ions of Earth's magnetosphere and its neutral exosphere and upper atmosphere gives rise to Energetic Neutral Atoms (ENAs). This has enabled several missions to remotely image the global injection dynamics of the ring current and plasma sheet, the outflow of ions from Earth's polar regions, and the location of the sub-solar magnetopause. In this presentation we review ENA observations by the Astrid, IMAGE, TWINS and IBEX missions. We focus on results from the IMAGE/HENA Camera including observations of proton and oxygen ion injections in to the ring current and their impact on the force-balance and ionospheric coupling in the inner magnetosphere. We report also on the status of inversion techniques for retrieving the ion spatial and pitch-angle distributions from ENA images. The presentation concludes with a discussion of future next steps in ENA instrumentation and analysis capabilities required to deliver the science as recommended by the Heliophysics Decadal Survey.

  6. Oscillation of Quasi-Steady Earth's Magnetosphere

    Institute of Scientific and Technical Information of China (English)

    HU You-Qiu; GUO Xiao-Cheng; LI Guo-Qiang; WANG Chi; HUANG Zhao-Hui

    2005-01-01

    @@ A three-dimensional magnetohydrodynamics (MHD) code is designed specially for global simulations of the solar wind-magnetosphere-ionosphere system. The code possesses a high resolution in capturing MHD shocks and discontinuities and a low numerical dissipation in examining possible instabilities inherent in the system. The ionosphere is approximated by a spherical shell with uniform height-integrated conductance. The solar wind is steady, and the interplanetary magnetic field is either due northward or due southward. The code is then run to find solutions of the whole system. It is found that the system has never reached a steady state, but keeps oscillating with a period of about one hour in terms of density variation at the geosynchronous orbit. However,if a certain artificial resistivity is added either in the whole numerical box or in the reconnection sites only, the reconnections change from intermittent to steady regime and the oscillation disappears accordingly. We conclude that the Earth's magnetosphere tends to be in a ceaseless oscillation status because of the low dissipation property inherent in the magnetospheric plasma, and the oscillation may be driven by intermittent magnetic reconnections that occur somewhere in the magnetopause and/or the magnetotail.

  7. Earth's magnetosphere - Global problems in magnetospheric plasma physics

    Science.gov (United States)

    Roederer, J. G.

    1979-01-01

    Magnetospheric physics is presently in a transition from the exploratory stage to one in which satellite missions and ground-based observations are planned with the specific object of achieving a global understanding and self-consistent quantitative description of the cause-and-effect relationship among the principal dynamic processes involved. Measurements turn to lower and lower energies and to higher ion mass species, in order to encompass the entire particle population, and to a broader range of the frequency spectrum of magnetic and electric field variations. In the present paper, the current status of our knowledge on magnetospheric plasma physics is reviewed, with particular reference of such fundamental advances as the discovery of layers of streaming plasma in the magnetosphere beneath its boundary surface, the identification of the terrestrial magnetosphere as a celestial source of kilometric radiation and relativistic particles, the identification of parallel electric field regions within the magnetosphere and their role in auroral particle acceleration, and the discovery of large fluxes of energetic heavy ions trapped in the magnetosphere.

  8. Observational Aspects of Magnetic Reconnection at the Earth's Magnetosphere

    Science.gov (United States)

    Souza, Vitor M.; Koga, Daiki; Gonzalez, Walter D.; Cardoso, Flavia R.

    2017-08-01

    Magnetic field reconnection has shown to be the dominant process in the solar wind-Earth's magnetosphere interaction. It enables mass, momentum, and energy exchange between different plasma regimes, and it is regarded as an efficient plasma acceleration and heating mechanism. Reconnection has been observed to occur in laboratory plasmas, at planetary magnetospheres in our Solar System, and the Sun. In this work, we focus on analyzing the characteristics of magnetic reconnection at the Earth's magnetosphere according to spaceborne observations in the vicinity of our planet. Firstly, the locations where magnetic field reconnection are expected to occur within the vast magnetospheric region are addressed, and is shown how they are influenced by changes in the interplanetary magnetic field direction. The main magnetic field and plasma signatures of magnetic reconnection are discussed from both theoretical and observational points of view. Spacecraft observations of ion inertial length scale reconnection are also presented.

  9. Earth's Magnetosphere Impinged by Interplanetary Shocks of Different Orientations

    Institute of Scientific and Technical Information of China (English)

    GUO Xiao-Cheng; HU You-Qiu; WANG Chi

    2005-01-01

    @@ Using a recently developed PPMLR-MHD code, we carry out a global numerical simulation of the interaction between interplanetary shocks and Earth's magnetosphere. The initial magnetosphere is in a quasi-steady state,embedded in a uniform solar wind and a spiral interplanetary magnetic field (IMF). An interplanetary (IP)shock interacts in turn with the bow shock, the magnetosheath, the magnetopause, and the magnetosphere, and changes the magnetosphere in shape and structure, and the distribution of the electric current and potential in the ionosphere as well. A preliminary comparison is made between two IP shocks of the same solar wind dynamic pressure and a vanishing IMF Bz on the downstream side, but with different propagation directions, one parallel and the other oblique to the Sun-Earth line. The numerical results show that both shocks cause a compression of the magnetosphere, an enhancement of magnetic field strength and field-aligned current in the magnetosphere, and an increase of the dawn-dusk electric potential drops across the polar ionosphere. Moreover, the magnetosphereionosphere system approaches a similar quasi-steady state after the interaction, for the downstream states are very close for the two shocks. However, the evolution processes of the system are remarkably different during the interaction with the two shocks of different orientations. The shock with the normal oblique to the Sun-Earth line results in a much longer evolution time for the system. This demonstrates that the shock orientation plays an important role in determining the associated geophysical effects and interpreting multisatellite observations of IP shock-magnetosphere interaction events.

  10. Auroral phenomenology and magnetospheric processes earth and other planets

    CERN Document Server

    Keiling, Andreas; Bagenal, Fran; Karlsson, Tomas

    2013-01-01

    Published by the American Geophysical Union as part of the Geophysical Monograph Series. Many of the most basic aspects of the aurora remain unexplained. While in the past terrestrial and planetary auroras have been largely treated in separate books, Auroral Phenomenology and Magnetospheric Processes: Earth and Other Planets takes a holistic approach, treating the aurora as a fundamental process and discussing the phenomenology, physics, and relationship with the respective planetary magnetospheres in one volume. While there are some behaviors common in auroras of the diffe

  11. Cosmic Rays in Magnetospheres of the Earth and other Planets

    CERN Document Server

    Dorman, Lev

    2009-01-01

    This monograph describes the behaviour of cosmic rays in the magnetosphere of the Earth and of some other planets. Recently this has become an important topic both theoretically, because it is closely connected with the physics of the Earth’s magnetosphere, and practically, since cosmic rays determine a significant part of space weather effects on satellites and aircraft. The book contains eight chapters, dealing with – The history of the discovery of geomagnetic effects caused by cosmic rays and their importance for the determination of the nature of cosmic rays or gamma rays – The first explanations of geomagnetic effects within the framework of the dipole approximation of the Earth’s magnetic field – Trajectory computations of cutoff rigidities, transmittance functions, asymptotic directions, and acceptance cones in the real geomagnetic field taking into account higher harmonics – Cosmic ray latitude-longitude surveys on ships, trains, tracks, planes, balloons and satellites for determining the...

  12. The statistical approach for turbulent processes in the Earth's magnetosphere

    Science.gov (United States)

    Kozak, Liudmyla; Savin, Sergey; Budaev, Vyacheslav; Pilipenko, Viacheslav

    The scaling features of the probability distribution functions (PDFs) of the magnetic field fluctuations in different regions of Earth magnetosphere and the solar wind plasma at different timescales were considered. Data obtained by Interball spacecraft were used. Changes of shape and parameters of the probability distribution function for periods of the satellite position in different magnetosphere regions were examined. The probabilities of return P(0) with t, and kurtosis values at different timescales were used for the analysis. Two asymptotic regimes of P(0) characterized by different power laws were founded. In particular, while the large timescale the scaling is quite well in agreement with the typical scaling features for a normal Gaussian process, in the limit of small timescale the observed scaling resembles the behavior of a Levy process. The crossover characteristic timescale is corresponding to 1 sec. This value can be connected with ion gyrofrequency. In addition, for the analysis of turbulent processes the structure functions of different orders were investigated, and comparison of the obtained results with log-Poisson cascade model was made. Near magnetospheric boundaries the statistical study reveals super-diffusive character of the transport processes. In the quiet magnetosheath and in solar wind classical diffusion is recovered.

  13. Global X-ray Imaging of the Earth's Magnetosphere

    Science.gov (United States)

    Branduardi-Raymont, G.

    2012-04-01

    Plasma and magnetic field environments can be studied in situ, or by remote sensing. In situ measurements return precise information about plasma composition, instabilities and dynamics, but cannot provide the global view necessary to understand the overall behaviour and evolution of the plasma, which instead can be explored by remote imaging. We propose a new approach by remote global X-ray imaging, now possible thanks to the relatively recent discovery of solar wind charge-exchange X-ray emission; this has been found, by observatories such as XMM-Newton, to occur in the vicinity of the Earth's magnetosphere and to peak in the sub-solar magnetosheath, where both solar wind and neutral exospheric densities are high. We describe how an appropriately designed and located X-ray telescope, supported by simultaneous in situ measurements of the solar wind, can be used to image the Earth's dayside magnetosphere, magnetosheath and bow shock, with temporal and spatial resolutions sufficient to address key outstanding questions concerning how the solar wind interacts with planetary magnetospheres. This medium-size mission incorporates a wide-field soft X-ray telescope, using micropore optics and CCD detectors, for imaging and spectroscopy, a proton and alpha particle sensor designed to measure the bulk properties of the solar wind, an ion composition analyser which aims to characterise the populations of minor ions in the solar wind, and a magnetometer for accurate measurements of the strength and direction of the magnetic field. Details of the mission profile will be presented, as well as simulations of the expected performance for possible mission configurations. The AXIOM Team: G. Branduardi-Raymont(1), S. F. Sembay(2), J. P. Eastwood(3), D. G. Sibeck(4), A. Abbey(2), P. Brown(3), J. A. Carter(2), C. M. Carr(3), C. Forsyth(1), D. Kataria(1), S. Milan(2), C. J. Owen(1), A. M. Read(2), C. S. Arridge(1), A. J. Coates(1), M. R. Collier(4), S. W. H. Cowley(2), G. Fraser(2), G

  14. The Transport of Solar Ions Through the Earth's Magnetosphere

    Science.gov (United States)

    Lennartsson, O. W.

    1999-01-01

    This report covers the initial phase of an investigation that was originally selected by NASA Headquarters for funding by a grant but was later transferred to NASA GSFC for continued funding under a new and separate contract. The principal objective of the investigation, led by Dr. O.W. Lennartsson, is to extract information about the solar origin plasma in Earth's magnetosphere, specifically about the entry and transport of this plasma, using energetic (10 eV/e to 18 keV/e) ion composition data from the Lockheed Plasma Composition Experiment on the NASA/ESA International Sun-Earth Explorer One (ISEE 1) satellite. These data were acquired many years ago, from November 1977 through March of 1982, but, because of subsequent failures of similar experiments on several other spacecraft, they are still the only substantial ion composition data available from Earth's magnetotail, beyond 10 R(sub E), in the critically important sub-kev to keV energy range. All of the Lockheed data now exist in a compacted scientific format, suitable for large-scale statistical investigations, which has been archived both at Lockheed Martin in Palo Alto and at the National Space Science Data Center (NSSDC) in Greenbelt. The completion of the archiving, by processing the remaining half of the data, was made possible by separate funding through a temporary NASA program for data restoration and was given priority over the data analysis by a no-cost extension of the subject grant. By chance, the period of performance coincided with an international study of source and loss processes of magnetospheric plasma, sponsored by the International Space Science Institute (ISSI) in Bern, Switzerland, for which Dr. Lennartsson was invited to serve as one of 12 co-chairs. This study meshed well with the continued analysis of the NASA/Lockheed ISEE ion composition data and provided a natural forum for a broader discussion of the results from this unique experiment. What follows is arranged, for the most

  15. The Transport of Solar Ions Through the Earth's Magnetosphere

    Science.gov (United States)

    Lennartsson, O. W.

    1999-01-01

    This report covers the initial phase of an investigation that was originally selected by NASA Headquarters for funding by a grant but was later transferred to NASA GSFC for continued funding under a new and separate contract. The principal objective of the investigation, led by Dr. O.W. Lennartsson, is to extract information about the solar origin plasma in Earth's magnetosphere, specifically about the entry and transport of this plasma, using energetic (10 eV/e to 18 keV/e) ion composition data from the Lockheed Plasma Composition Experiment on the NASA/ESA International Sun-Earth Explorer One (ISEE 1) satellite. These data were acquired many years ago, from November 1977 through March of 1982, but, because of subsequent failures of similar experiments on several other spacecraft, they are still the only substantial ion composition data available from Earth's magnetotail, beyond 10 RE, in the critically important sub-kev to keV energy range. All of the Lockheed data now exist in a compacted scientific format, suitable for large-scale statistical investigations, which has been archived both at Lockheed Martin in Palo Alto and at the National Space Science Data Center (NSSDC) in Greenbelt. The completion of the archiving, by processing the remaining half of the data, was made possible by separate funding through a temporary NASA program for data restoration and was given priority over the data analysis by a no-cost extension of the subject grant. By chance, the period of performance coincided with an international study of source and loss processes of magnetospheric plasma, sponsored by the International Space Science Institute (ISSI) in Bern, Switzerland, for which Dr. Lennartsson was invited to serve as one of 12 co-chairs. This study meshed well with the continued analysis of the NASA/Lockheed ISEE ion composition data and provided a natural forum for a broader discussion of the results from this unique experiment. What follows is arranged, for the most part, in

  16. Plasma boundary layer and magnetopause layer of the earth's magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Eastman, T.E.

    1979-06-01

    IMP 6 observations of the plasma boundary layer (PBL) and magnetopause layer (MPL) of the earth's magnetosphere indicate that plasma in the low-latitude portion of the PBL is supplied primarily by direct transport of magnetosheath plasma across the MPL and that this transport process is relatively widespread over the entire sunward magnetospheric boundary.

  17. Observations of Electrostatic and Electromagnetic Waves in the Earth's Magnetosphere.

    Science.gov (United States)

    Filbert, Paul Charles

    Using data from the University of Minnesota Plasma Wave Experiment aboard the IMP-6 (Explorer 43) satellite, three topics are addressed. The first concerns the wave lengths of certain electrostatic waves in the earth's magnetosphere. Using the fact that the X and Y dipole antennas on IMP-6 are of unequal length, the antenna response to electrostatic waves is calculated as a function of wavelength. This result is used to experimentally determine the wavelengths of Bernstein mode waves observed just beyond the plasmapause. These wavelengths are then used in conjunction with present theoretical models to determine the energy of the electrons driving these waves and a range of energies between (TURN) several tens to (TURN) several hundreds of electron volts is found. This procedure is also applied to Langmuir waves observed upstream of the earth's bow shock and the results are in good agreement with theoretical predictions. Second it is demonstrated that enhanced levels of the so-called continuum radiation are correlated with AE enhancements. In addition, a source region of continuum radiation is directly observed and movement of the source region is seen which is consistent with a cloud of electrons having been injected into the night side magnetosphere and undergoing gradient drifts in an eastward direction towards local dawn. This drift movement is then used to estimate the energy of the electrons which produce the observed continuum enhancement and a range between 10 kev to 50 kev is found. Spectral properties of the directly observed source are also presented, and indicate a high frequency spectral index of (TURN)f('-5.5). A new type of continuum radiation which correlates with TKR on a time scale of (TURN)1 minute is also observed and is found to have a source region distinct from that mentioned above. Third, a correlation between TKR and VLF auroral hiss has been observed for several high latitude passes of IMP-6 through the midnight auroral zone. This

  18. Localization of energetic electrons in the earth's outer magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Antonova, A.E. (Moskovskii Gosudarstvennyi Universitet, Moscow, USSR); Nikolaeva, N.S. (Akademiia Nauk SSSR, Institut Kosmicheskikh Issledovanii, Moscow, USSR)

    1979-09-01

    The distribution of fluxes of electrons with energies greater than 40 keV and greater than 300 keV is analyzed, which were recorded by Prognoz 3 in various sectors of the outer magnetosphere. Using Mead-Fairfield's (1975) empirical model of the magnetosphere, the regions with the highest electron fluxes are projected onto the earth's surface and the geomagnetic equator. The distribution obtained reveals the presence of considerable fluxes at the day side, including the region adjacent to the equatorial boundary along the lines of force that intersect the plasma layer of the magnetospheric tail.

  19. Simulation in the Front Region of the Earth's Magnetosphere

    Directory of Open Access Journals (Sweden)

    Gung Yur

    2012-01-01

    Full Text Available A laboratory experiment was conducted to investigate the interaction between a plasma beam and a magnetic dipole, simulating the interaction between the solar wind and magnetized planets. The emphasis in this paper is on the laboratory simulation in the front region of the _ magnetosphere and their variation under different solar wind conditions. The boundary in the front region of the magnetosphere is observed in a space simulation laboratory and the magnetospheric structure is produced by a super-Alfvénic and collisionless plasma beam interacting with terrella field. The boundary of the magnetosphere is determined by the factors that include solar wind parameters, such as magnetic fields, ion current density and magnetospheric structure images. It is interesting to compare the results of laboratory simulations with the empirical model by Shue et al. (1997 and the theoretical model by Cheng (1998 as well for the prediction of magnetopause locations under any solar wind condition. The comparisons show that for the northward IMF, magnetopause locations in the laboratory simulation are consistent with the theoretical model. As the magnitude of northward IMF Bz becomes higher, the subsolar distance and the flank position in laboratory simulations are consistent with the empirical model as well. For a lower southward IMF Bz, magnetopause locations in laboratory simulations are consistent with both the empirical and theoretical models. As the magnitude of the southward IMF Bz becomes higher, the subsolar distance and the flank position in laboratory simulations seem closer to the theoretical model than the empirical model.

  20. Near-Earth Magnetic Field Effects of Large-Scale Magnetospheric Currents

    DEFF Research Database (Denmark)

    Lühr, Hermann; Xiong, Chao; Olsen, Nils

    2017-01-01

    Magnetospheric currents play an important role in the electrodynamics of near-Earth space. This has been the topic of many space science studies. Here we focus on the magnetic fields they cause close to Earth. Their contribution to the geomagnetic field is the second largest after the core field...

  1. IMF dependence of energetic oxygen and hydrogen ion distributions in the near-Earth magnetosphere

    Science.gov (United States)

    Luo, H.; Kronberg, E. A.; Nykyri, K.; Trattner, K. J.; Daly, P. W.; Chen, G. X.; Du, A. M.; Ge, Y. S.

    2017-05-01

    Energetic ion distributions in the near-Earth plasma sheet can provide important information for understanding the entry of ions into the magnetosphere and their transportation, acceleration, and losses in the near-Earth region. In this study, 11 years of energetic proton and oxygen observations (> 274 keV) from Cluster/Research with Adaptive Particle Imaging Detectors were used to statistically study the energetic ion distributions in the near-Earth region. The dawn-dusk asymmetries of the distributions in three different regions (dayside magnetosphere, near-Earth nightside plasma sheet, and tail plasma sheet) are examined in Northern and Southern Hemispheres. The results show that the energetic ion distributions are influenced by the dawn-dusk interplanetary magnetic field (IMF) direction. The enhancement of ion intensity largely correlates with the location of the magnetic reconnection at the magnetopause. The results imply that substorm-related acceleration processes in the magnetotail are not the only source of energetic ions in the dayside and the near-Earth magnetosphere. Energetic ions delivered through reconnection at the magnetopause significantly affect the energetic ion population in the magnetosphere. We also believe that the influence of the dawn-dusk IMF direction should not be neglected in models of the particle population in the magnetosphere.

  2. A three dimensional MHD model of the earth's magnetosphere

    Science.gov (United States)

    Wu, C. C.; Walker, R. J.; Dawson, J. M.

    1981-01-01

    The results of a global MHD calculation of the steady state solar wind interaction with a dipole magnetic field are presented. The computer code used, being much faster than previous codes, makes it possible to increase the number of grid points in the system by an order of magnitude. The resulting model qualitatively reproduces many of the observed features of the quiet time magnetosphere including the bow shock, magnetopause, and plasma sheet.

  3. One year in the Earth's magnetosphere: A global MHD simulation and spacecraft measurements

    CERN Document Server

    Facsko, G; Zivkovic, T; Palin, L; Kallio, E; Agren, K; Opgenoorth, H; Tanskanen, E I; Milan, S E

    2016-01-01

    The response of the Earth's magnetosphere to changing solar wind conditions are studied with a 3D Magnetohydrodynamic (MHD) model. One full year (155 Cluster orbits) of the Earth's magnetosphere is simulated using Grand Unified Magnetosphere Ionosphere Coupling simulation (GUMICS-4) magnetohydrodynamic code. Real solar wind measurements are given to the code as input to create the longest lasting global magnetohydrodynamics simulation to date. The applicability of the results of the simulation depends critically on the input parameters used in the model. Therefore, the validity and the variance of the OMNIWeb data is first investigated thoroughly using Cluster measurement close to the bow shock. The OMNIWeb and the Cluster data were found to correlate very well before the bow shock. The solar wind magnetic field and plasma parameters are not changed significantly from the $L_1$ Lagrange point to the foreshock, therefore the OMNIWeb data is appropriate input to the GUMICS-4. The Cluster SC3 footprints are dete...

  4. Tunneling and mode conversion of fast magnetosonic waves in the magnetospheres of Earth and Mercury

    CERN Document Server

    Kazakov, Yevgen O

    2014-01-01

    Narrow-band linearly polarized waves, having a resonant structure and a peak frequency between the local cyclotron frequency of protons and heavy ions, have been detected in the magnetospheres of Earth and of Mercury. Some of these wave events have been suggested to be driven by linear mode conversion (MC) of the fast magnetosonic waves at the ion-ion hybrid (IIH) resonances. Since the resonant IIH frequency is linked to the plasma composition, solving the inverse problem allows one to infer the concentration of the heavy ions from the measured frequency spectra. In this paper, we identify the conditions when the MC efficiency is maximized in the magnetospheric plasmas and discuss how this can be applied for estimating the heavy ion concentration in the magnetospheres of Earth and Mercury.

  5. On the Magnetospheric Engine Behind Kilometric Radiation at Earth and Saturn

    Science.gov (United States)

    Brandt, Pontus; Mitchell, Donald

    2014-05-01

    The planets of the solar system display a range of different space environments and solar interaction regimes, from non/weakly magnetized, to magnetized with convective- versus rotation-dominated magnetospheres. All magnetized planets with an appreciable magnetosphere are immersed in a dynamic energetic particle (hot plasma), as well as cold plasma, environment. These five planetary magnetospheres (Earth, Jupiter, Saturn, Uranus and Neptune) are also significant emitters of low-frequency radio waves that are consistent with a cyclotron-maser instability set up in a field-aligned current region. Radio observations in the Kilometric Radiation (AKR) emissions in the ~30-800 kHz range have long been known to be associated with auroral intensifications and magnetospheric substorms. In a similar fashion, recent remote imaging using Energetic Neutral Atoms (ENAs) obtained by the Cassini mission have revealed that the periodic Saturn Kilometric Radiation (SKR) emission from Saturn's high-latitude magnetosphere is highly correlated with simultaneous large-scale injections of energetic particles in the night side magnetosphere. These observations imply that the engine behind the AKR and SKR is current system associated with the planet ward fast plasma flows during an injection and/or the resulting plasma pressure gradients of the heated plasma.

  6. Earth's magnetosphere formed by the low-latitude boundary layer

    CERN Document Server

    Heikkila, W J

    2011-01-01

    The author argues that, after five decades of debate about the interactive of solar wind with the magnetosphere, it is time to get back to basics. Starting with Newton's law, this book also examines Maxwell's equations and subsidiary equations such as continuity, constitutive relations and the Lorentz transformation; Helmholtz' theorem, and Poynting's theorem, among other methods for understanding this interaction. Includes chapters on prompt particle acceleration to high energies, plasma transfer event, and the low latitude boundary layer More than 200 figures illustrate the text Includes a color insert.

  7. Determination of the arrival time of ICME Shock to Earth's Magnetosphere

    Science.gov (United States)

    Shaltout, Mosalam; Mahrous, Ayman; Shaltout, Mosalam; Youssef, Mohamed; Ramy Mawad, Rr.

    . We are estimated the arrival time of ICME shock to the Earth's magnetosphere during the solar cycle 23rd , for the period 1996-2005, by using certain temporal and spatial conditions. We selected the Data of the SSC events from Preliminary Reports of the ISGI (Institut de Physique du Globe, France). While the associated CMES during the same period are selected from SOHO/LASCO/C2. We construct a numerical model to estimate the arrival time of the CME reached the Earth's magnetosphere. According to our model, we found high correlation between CMEs and their shocks (R = 75%). In addition , we studied the characteristics of the CMEs which reached to Earth's magnetosphere. Also we examined the relation between the logarithms of the halo CME energy and the duration of the associated intense geomagnetic storms(Dst < -100nT ). We found a significant correlation (R = 0.82) between the length of the duration of the intense geomagnetic storms and the related halo CME energies. This means that the halo CMEs events is the main source of the energy transfer processes into the Earth's magnetosphere.

  8. Kinetic models of magnetic flux ropes observed in the Earth magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Vinogradov, A. A. [Department of Physics, Lomonosov Moscow State University, Moscow (Russian Federation); Vasko, I. Y.; Petrukovich, A. A.; Zelenyi, L. M. [Space Research Institute of Russian Academy of Sciences, Moscow (Russian Federation); Artemyev, A. V. [Space Research Institute of Russian Academy of Sciences, Moscow (Russian Federation); University of California, Los Angeles, California 90095 (United States); Yushkov, E. V. [Department of Physics, Lomonosov Moscow State University, Moscow (Russian Federation); Space Research Institute of Russian Academy of Sciences, Moscow (Russian Federation)

    2016-07-15

    Magnetic flux ropes (MFR) are universal magnetoplasma structures (similar to cylindrical screw pinches) formed in reconnecting current sheets. In particular, MFR with scales from about the ion inertial length to MHD range are widely observed in the Earth magnetosphere. Typical MFR have force-free configuration with the axial magnetic field peaking on the MFR axis, whereas bifurcated MFR with an off-axis peak of the axial magnetic field are observed as well. In the present paper, we develop kinetic models of force-free and bifurcated MFR and determine consistent ion and electron distribution functions. The magnetic field configuration of the force-free MFR represents well-known Gold-Hoyle MFR (uniformly twisted MFR). We show that bifurcated MFR are characterized by the presence of cold and hot current-carrying electrons. The developed models are capable to describe MFR observed in the Earth magnetotail as well as MFR recently observed by Magnetospheric Multiscale Mission at the Earth magnetopause.

  9. Sensitivity of the Earth Magnetosphere to the Solar Wind Activity: 3D Macroparticle Model

    Science.gov (United States)

    Baraka, S. M.; Ben Jaffel, L.

    2006-05-01

    A new approach is proposed to study the sensitivity of the Earth Magnetosphere to the variability of the Solar Wind bulk velocity. A numerical particles in cell (PIC) method initially proposed by Buneman (1993) has been adopted and modified to carry out the study. Space was stretched as cubic boxes of dimension 155x105x105 Re filled with 2 million of Solar Wind particles, with Earth is located at 60x52x53 Re. The magnetic field of Earth was hypothetically set to zero, and then switched on. The formation of the magnetospheric cavity and its elongation around the planet was observed to evolve with time until a steady state topology of the system is attained with the classical structure of a magnetosphere. We also found that the cavity is repopulated by clouds of particles from the Solar Wind, producing the current sheet-- a thin plasma sheet that stands at the equatorial plane. The study was carried out with the very basic elements of the interaction processes as described by Maxwell and Lorentz equations. IMF was then included as a steady southward magnetic field. Drift velocity of the Solar Wind was changed to simulate compression/depression of the system. 3-D analysis of the response of the magnetosphere dayside to that variation was studied, and the corresponding relaxation time of the magnetopause interface was measured. In response to the Solar Wind drift velocity imposed drop-off, a ~ 15 Re gap in the incoming Solar Wind plasma appeared moving toward Earth. As soon as the gap hit the initial shock of the steady magnetosphere, a reconnection between the Earth magnetic field and IMF was noticed at the dayside magnetopause when IMF was included. Injection of nightside of the magnetosphere by energetic particles due to magnetic erosion and reconnection is observed. During the expansion phase of the disturbance, the outer boundary of the dayside magnetopause broke up during the absence of the IMF as it responded to the reduction of the ram pressure, whilst

  10. The Earth's magnetosphere is 165 R(sub E) long: Self-consistent currents, convection, magnetospheric structure, and processes for northward interplanetary magnetic field

    Science.gov (United States)

    Fedder, J. A.; Lyon, J. G.

    1995-01-01

    The subject of this paper is a self-consistent, magnetohydrodynamic numerical realization for the Earth's magnetosphere which is in a quasi-steady dynamic equilibrium for a due northward interplanetary magnetic field (IMF). Although a few hours of steady northward IMF are required for this asymptotic state to be set up, it should still be of considerable theoretical interest because it constitutes a 'ground state' for the solar wind-magnetosphere interaction. Moreover, particular features of this ground state magnetosphere should be observable even under less extreme solar wind conditions. Certain characteristics of this magnetosphere, namely, NBZ Birkeland currents, four-cell ionospheric convection, a relatively weak cross-polar potential, and a prominent flow boundary layer, are widely expected. Other characteristics, such as no open tail lobes, no Earth-connected magnetic flux beyond 155 R(sub E) downstream, magnetic merging in a closed topology at the cusps, and a 'tadpole' shaped magnetospheric boundary, might not be expected. In this paper, we will present the evidence for this unusual but interesting magnetospheric equilibrium. We will also discuss our present understanding of this singular state.

  11. Data Mining for Vortices on the Earth's Magnetosphere

    Science.gov (United States)

    Collado-Vega, Y. M.; Kalb, V.; Sibeck, D. G.

    2016-12-01

    This research validates a method to detect and characterize vortices based on velocity from simulation data. The current algorithm involves systematically searching the 3-dimensional velocity fields to identify critical points, points where the magnitude of the velocity vector field vanishes, making these points candidates for vortex centers. We utilize the Community Coordinated Modeling Center (CCMC) run on request capability to create a series of model runs initialized from the conditions observed by the Cluster mission in the Hwang et al., 2011 analysis of Kelvin Helmholtz vortices observed during southward IMF. The fast data characterization and vortex detection will permit the scientist to focus in on different magnetosphere locations for further investigation in large data sets. This not only saves time to scientist, but also diminishes the potential for missing features of interest. We also analyze further the properties of the vortices found including the velocity changes within their motion across the magnetosheath, and the potential of our tool to characterize transient features (e.g. Flux Transfer Event (FTEs)) with vortical internal structures.

  12. Earth's magnetosphere and outer radiation belt under sub-Alfvénic solar wind

    Science.gov (United States)

    Lugaz, Noé; Farrugia, Charles J.; Huang, Chia-Lin; Winslow, Reka M.; Spence, Harlan E.; Schwadron, Nathan A.

    2016-10-01

    The interaction between Earth's magnetic field and the solar wind results in the formation of a collisionless bow shock 60,000-100,000 km upstream of our planet, as long as the solar wind fast magnetosonic Mach (hereafter Mach) number exceeds unity. Here, we present one of those extremely rare instances, when the solar wind Mach number reached steady values hours on 17 January 2013. Simultaneous measurements by more than ten spacecraft in the near-Earth environment reveal the evanescence of the bow shock, the sunward motion of the magnetopause and the extremely rapid and intense loss of electrons in the outer radiation belt. This study allows us to directly observe the state of the inner magnetosphere, including the radiation belts during a type of solar wind-magnetosphere coupling which is unusual for planets in our solar system but may be common for close-in extrasolar planets.

  13. Dynamics of the earth's radiation belts and inner magnetosphere (geophysical monograph series)

    CERN Document Server

    2013-01-01

    Dynamics of the Earth's Radiation Belts and Inner Magnetosphere draws together current knowledge of the radiation belts prior to the launch of Radiation Belt Storm Probes (RPSP) and other imminent space missions, making this volume timely and unique. The volume will serve as a useful benchmark at this exciting and pivotal period in radiation belt research in advance of the new discoveries that the RPSP mission will surely bring. Highlights include the following: a review of the current state of the art of radiation belt science; a complete and up-to-date account of the wave-particle interactions that control the dynamical acceleration and loss processes of particles in the Earth's radiation belts and inner magnetosphere; a discussion emphasizing the importance of the cross-energy coupling of the particle populations of the radiation belts, ring current, and plasmasphere in controlling the dynamics of the inner magnetosphe...

  14. The magnetopause as an intermediary between interplanetary structures and the Earth's inner magnetosphere

    Science.gov (United States)

    Hwang, K.; Sibeck, D. G.; Fok, M. H.; Zheng, Y.; Glocer, A.; Mitchell, D. G.

    2013-12-01

    Observational studies using data from multipoint spacecraft combined with global modeling of the Earth's magnetosphere are presented to understand the magnetopause as an intermediary between interplanetary structures and the inner magnetosphere in response to a variety of solar-wind structures, such as Coronal Mass Ejections (CMEs), Corotating Interaction Regions (CIRs), interplanetary shocks, and pressure pulses. The importance of the magnetopause in the solar wind-inner magnetosphere coupling arises not only from its global motion, which determines the location of the magnetopause relative to the drift paths of outer radiation-belt particles, but also from physical processes occurring at the magnetopause boundary layer. Common physical processes occurring at the magnetopause boundary layer include Kelvin-Helmholtz waves and newly-identified velocity fluctuations, which both provide multiple channels to increase, decrease, or modulate inner-magnetospheric particle density/energy fluxes. We have surveyed the data sets, finding a number of events in which THEMIS observed magnetopause boundary waves while the Van Allen Probes observed flux enhancements in response to various solar-wind structures. Ultra-Low-Frequency (ULF) waves are often excited by, or enhanced, during these boundary fluctuations. Simultaneous intensifications and/or modulations in the energetic radiation belt and ring current populations are common. Amongst these events, we present categorized case studies in which inner-magnetospheric fluxes are regulated by different solar wind-magnetopause couplings. These results provide evidence that the energy from the interplanetary structures is transferred into the inner magnetosphere via magnetopause dynamics. We use measurements from multiple spacecraft including the Van Allen Probes and the THEMIS and global MHD simulations to track down the mechanisms by which this transport is implemented.

  15. Observation of a Hydromagnetic Wave in the Earth’s Magnetosphere.

    Science.gov (United States)

    1987-12-01

    traveling Alfven wave guided by the earth’s magnetic field line. Plasma densities are calculated at L = 7. The phase relationship between the plasma ...verify the measurement of the electric field. Current magnetospheric models predicting Alfven wave speeds, Alfven wave periods and plasma densities are...Advisor S. Gnan am, Secon Reader(1/ Karl inz I. Woe er, Carman , Department of Physics Go E. Schacher Dean of Science and Engineering 2 ABSTRACT

  16. Detection of a plasmaspheric wind in the Earth's magnetosphere by the Cluster spacecraft

    Directory of Open Access Journals (Sweden)

    I. Dandouras

    2013-07-01

    Full Text Available Plumes, forming at the plasmapause and released outwards, constitute a well-established mode for plasmaspheric material release to the Earth's magnetosphere. They are associated to active periods and the related electric field change. In 1992, Lemaire and Shunk proposed the existence of an additional mode for plasmaspheric material release to the Earth's magnetosphere: a plasmaspheric wind, steadily transporting cold plasmaspheric plasma outwards across the geomagnetic field lines, even during prolonged periods of quiet geomagnetic conditions. This has been proposed on a theoretical basis. Direct detection of this wind has, however, eluded observation in the past. Analysis of ion measurements, acquired in the outer plasmasphere by the CIS experiment onboard the four Cluster spacecraft, provide now an experimental confirmation of the plasmaspheric wind. This wind has been systematically detected in the outer plasmasphere during quiet and moderately active conditions, and calculations show that it could provide a substantial contribution to the magnetospheric plasma populations outside the Earth's plasmasphere. Similar winds should also exist on other planets, or astrophysical objects, quickly rotating and having an atmosphere and a magnetic field.

  17. First Observations of a Foreshock Bubble at Earth: Implications for Magnetospheric Activity and Energetic Particle Acceleration

    Science.gov (United States)

    Turner, D. L.; Omidi, N.; Sibeck, D. G.; Angelopoulos, V.

    2011-01-01

    Earth?s foreshock, which is the quasi-parallel region upstream of the bow shock, is a unique plasma region capable of generating several kinds of large-scale phenomena, each of which can impact the magnetosphere resulting in global effects. Interestingly, such phenomena have also been observed at planetary foreshocks throughout our solar system. Recently, a new type of foreshock phenomena has been predicted: foreshock bubbles, which are large-scale disruptions of both the foreshock and incident solar wind plasmas that can result in global magnetospheric disturbances. Here we present unprecedented, multi-point observations of foreshock bubbles at Earth using a combination of spacecraft and ground observations primarily from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission, and we include detailed analysis of the events? global effects on the magnetosphere and the energetic ions and electrons accelerated by them, potentially by a combination of first and second order Fermi and shock drift acceleration processes. This new phenomena should play a role in energetic particle acceleration at collisionless, quasi-parallel shocks throughout the Universe.

  18. Testing the hypothesis of the Earth's magnetosphere behaving like an avalanching system

    Directory of Open Access Journals (Sweden)

    A. T. Y. Lui

    2004-01-01

    Full Text Available The global auroral dissipation power as observed by the imager on the Polar spacecraft is used as a proxy for the power dissipation of the Earth's magnetosphere to examine whether or not the magnetosphere is an avalanching system. It is found that the probability density distributions for the area and power of auroral activity sites have a power law component within a finite scale range, suggestive of a scale-free nature in this finite-size system. This property is robust, prevailing with variations in the threshold used to define auroral activity sites and in the strength of the external driver, namely, the solar wind. The statistical characteristics on the temporal evolution of auroral sites are then examined, which leads to a criterion that can be used to predict about 42min in advance the total energy dissipation during the lifetime of an auroral activity site. The scale-free characteristics of auroral activity appears to be an intrinsic feature of the magnetosphere based on a comparison of the probability density distribution in the total auroral brightness power with that of the solar wind power input parameters in the same period as the auroral observations. These results are consistent with the hypothesis of the magnetosphere behaving like an avalanching system.

  19. Magnetoseismology ground-based remote sensing of Earth's magnetosphere

    CERN Document Server

    Menk, Frederick W

    2013-01-01

    Written by a researcher at the forefront of the field, this first comprehensive account of magnetoseismology conveys the physics behind these movements and waves, and explains how to detect and investigate them. Along the way, it describes the principles as applied to remote sensing of near-Earth space and related remote sensing techniques, while also comparing and intercalibrating magnetoseismology with other techniques. The example applications include advanced data analysis techniques that may find wider used in areas ranging from geophysics to medical imaging, and remote sensing using radar systems that are of relevance to defense surveillance systems. As a result, the book not only reviews the status quo, but also anticipates new developments. With many figures and illustrations, some in full color, plus additional computational codes for analysis and evaluation. Aimed at graduate readers, the text assumes knowledge of electromagnetism and physical processes at degree level, but introductory chapters wil...

  20. Simulation of the Earth's paleo-magnetosphere for the late Hadean eon

    Science.gov (United States)

    Scherf, Manuel; Khodachenko, Maxim; Blokhina, Marina; Johnstone, Colin; Alexeev, Igor; Belenkaya, Elena; Tarduno, John; Güdel, Manuel; Lammer, Helmut

    2016-04-01

    Simulations of the Earth's magnetosphere obstacle, including the shape of the auroral oval and related field lines for early stages of the solar system are of particular importance for studying the evolution and mass loss of the Earth's atmosphere. Within this presentation, we will present simulations of the terrestrial paleo-magnetosphere of the Earth for the late Hadean, i.e. for ˜4.1 billion years ago. These were performed with an adapted version of the Paraboloid Magnetospheric Model (PMM) of the Skobeltsyn Institute for Nuclear Physics of the Moscow State University, which serves as an ISO standard for the Earth's magnetosphere (see e.g. Alexeev et al., 2003). As an input parameter, the new measurements of the paleomagnetic field strength by Tarduno et al., 2015, are taken. These data from zircons between 3.3 billion and 4.2 billion years old vary between 1.0 and 0.12 of today's equatorial field strength. Available data at ˜4.1 billion years ago are among the lowest field strength values. Another input into the adapted PMM is the solar wind pressure, which was derived from a newly developed solar/stellar wind evolution model (Johnston et al., 2015a, b), which is strongly dependent on the rotation rate of the early Sun. Our simulations of the terrestrial paleo-magnetosphere with the adapted PMM show that for the most extreme case of a fast rotating Sun and a paleomagnetic field strength with 0.12 of today's value, the stand-off distance of the magnetopause Rs shrinks down from today's 10 Re to 3.43 Re. Even for a slow rotating Sun Rs would be at only 4.27 Re. Taking the same magnetic field strength as that of today and a slow rotating Sun leads to an Rs of 8.23 Re, which would be the least extreme case for the terrestrial atmosphere. Another outcome of the modelling is that the auroral oval was significantly broader ˜4.1 billion years ago than today. As demonstrated by our calculations a good approach of the relationship between auroral oval size Θpc (

  1. Chorus source region localization in the Earth's outer magnetosphere using THEMIS measurements

    Directory of Open Access Journals (Sweden)

    O. Agapitov

    2010-06-01

    Full Text Available Discrete ELF/VLF chorus emissions, the most intense electromagnetic plasma waves observed in the Earth's radiation belts and outer magnetosphere, are thought to propagate roughly along magnetic field lines from a localized source region near the magnetic equator towards the magnetic poles. THEMIS project Electric Field Instrument (EFI and Search Coil Magnetometer (SCM measurements were used to determine the spatial scale of the chorus source localization region on the day side of the Earth's outer magnetosphere. We present simultaneous observations of the same chorus elements registered onboard several THEMIS spacecraft in 2007 when all the spacecraft were in the same orbit. Discrete chorus elements were observed at 0.15–0.25 of the local electron gyrofrequency, which is typical for the outer magnetosphere. We evaluated the Poynting flux and wave vector distribution and obtained chorus wave packet quasi-parallel propagation to the local magnetic field. Amplitude and phase correlation data analysis allowed us to estimate the characteristic spatial correlation scale transverse to the local magnetic field to be in the 2800–3200 km range.

  2. Near-Earth Magnetic Field Effects of Large-Scale Magnetospheric Currents

    Science.gov (United States)

    Luehr, Hermann; Xiong, Chao; Olsen, Nils; Le, Guan

    2016-01-01

    Magnetospheric currents play an important role in the electrodynamics of near- Earth space. This has been the topic of many space science studies. Here we focus on the magnetic fields they cause close to Earth. Their contribution to the geomagnetic field is the second largest after the core field. Significant progress in interpreting the magnetic fields from the different sources has been achieved thanks to magnetic satellite missions like Ørsted, CHAMP and now Swarm. Of particular interest for this article is a proper representation of the magnetospheric ring current effect. Uncertainties in modelling its effect still produce the largest residuals between observations and present-day geomagnetic field models. A lot of progress has been achieved so far, but there are still open issues like the characteristics of the partial ring current. Other currents discussed are those flowing in the magnetospheric tail. Also their magnetic contribution at LEO orbits is non-negligible. Treating them as an independent source is a more recent development, which has cured some of the problems in geomagnetic field modelling. Unfortunately there is no index available for characterizing the tail current intensity. Here we propose an approach that may help to properly quantify the magnetic contribution from the tail current for geomagnetic field modelling. Some open questions that require further investigation are mentioned at the end.

  3. Simulation in the Front Region of the Earth¡¦s Magnetosphere

    Directory of Open Access Journals (Sweden)

    Gung Yur

    2012-01-01

    Full Text Available A laboratory experiment was conducted to investigate the interaction between a plasma beam and a magnetic dipole, simulating the interaction between the solar wind and magnetized planets. The emphasis in this paper is on the laboratory simulation in the front region of the Earth¡¦s magnetosphere and their variation under different solar wind conditions. The boundary in the front region of the magnetosphere is observed in a space simulation laboratory and the magnetospheric structure is produced by a super-Alfvénic and collisionless plasma beam interacting with terrella field. The boundary of the magnetosphere is determined by the factors that include solar wind parameters, such as magnetic fields, ion current density and magnetospheric structure images. It is interesting to compare the results of laboratory simulations with the empirical model by Shue et al. (1997 and the theoretical model by Cheng (1998 as well for the prediction of magnetopause locations under any solar wind condition. The comparisons show that for the northward IMF, magnetopause locations in the laboratory simulation are consistent with the theoretical model. As the magnitude of northward IMF Bz becomes higher, the subsolar distance and the flank position in laboratory simulations are consistent with the empirical model as well. For a lower southward IMF Bz, magnetopause locations in laboratory simulations are consistent with both the empirical and theoretical models. As the magnitude of the southward IMF Bz becomes higher, the subsolar distance and the flank position in laboratory simulations seem closer to the theoretical model than the empirical model.

  4. On the Earth's paleo-magnetosphere for the late Hadean eon

    Science.gov (United States)

    Scherf, Manuel; Khodachenko, Maxim; Blokhina, Marina; Johnstone, Colin; Alexeev, Igor; Belenkaya, Elena; Tarduno, John; Tu, Lin; Lichtenegger, Herbert; Guedel, Manuel; Lammer, Helmut

    2016-10-01

    Simulations of the terrestrial paleo-magnetosphere for early stages of the solar system are of particular importance for studying the evolution and mass loss of the Earth's atmosphere. Within this presentation, we will present simulations of the paleo-magnetosphere of the Earth for the late Hadean, i.e. for ~4.1 billion years ago. These were performed with an adapted version of the Paraboloid Magnetospheric Model (PMM) of the Skobeltsyn Institute for Nuclear Physics of the Moscow State University, which serves as an ISO standard for the magnetosphere . As an input parameter, the new measurements of the paleomagnetic field strength by Tarduno et al., 2015, are taken. These data from zircons between 3.3 billion and 4.2 billion years old vary between 1.0 and 0.12 of today's equatorial field strength. Available data at ~4.1 billion years ago are among the lowest field strength values. Another input into the adapted PMM is the solar wind pressure, which was derived from a newly developed solar/stellar wind evolution model, which is strongly dependent on the rotation rate of the early Sun.Our simulations of the terrestrial paleo-magnetosphere with the adapted PMM show that for the most extreme case of a fast rotating Sun and a paleomagnetic field strength with 0.12 of today's value, the stand-off distance of the magnetopause rs shrinks significantly down from today's 10-11 RE to 3.43 RE (i.e. 2.43 RE above the Earth's surface, where RE is the Earth's surface). Even for the least extreme case - i.e. the same magnetic field strength as that of today and a slow rotating Sun - rs shrinks down to 8.23 RE. Another outcome of the modelling is that the polar cap was significantly broader ~4.1 billion years ago than today.These results have implications for the early terrestrial atmosphere. Since the EUV flux during the late Hadean eon was significantly higher, the exobase of a nitrogen dominated atmosphere would most probably have reached the magnetopause, leading to enhanced

  5. Magnetosphere-ionosphere interactions: Near Earth manifestations of the plasma universe

    Science.gov (United States)

    Faelthammar, Carl-Gunne

    1986-01-01

    As the universe consists almost entirely of plasma, the understanding of astrophysical phenomena must depend critically on the understanding of how matter behaves in the plasma state. In situ observations in the near Earth cosmical plasma offer an excellent opportunity of gaining such understanding. The near Earth cosmical plasma not only covers vast ranges of density and temperature, but is the site of a rich variety of complex plasma physical processes which are activated as a results of the interactions between the magnetosphere and the ionosphere. The geomagnetic field connects the ionosphere, tied by friction to the Earth, and the magnetosphere, dynamically coupled to the solar wind. This causes an exchange of energy an momentum between the two regions. The exchange is executed by magnetic-field-aligned electric currents, the so-called Birkeland currents. Both directly and indirectly (through instabilities and particle acceleration) these also lead to an exchange of plasma, which is selective and therefore causes chemical separation. Another essential aspect of the coupling is the role of electric fields, especially magnetic field aligned (parallel) electric fields, which have important consequences both for the dynamics of the coupling and, especially, for energization of charged particles.

  6. Climatology of high-β plasma measurements in Earth's inner magnetosphere

    Science.gov (United States)

    Cohen, Ross; Gerrard, Andrew J.; Lanzerotti, Louis J.; Soto-Chavez, A. R.; Kim, Hyomin; Manweiler, Jerry W.

    2017-01-01

    Since their launch in August 2012, the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instruments on the NASA Van Allen Probes spacecraft have been making continuous high-resolution measurements of Earth's ring current plasma environment. After a full traversal through all magnetic local times, a climatology (i.e., a survey of observations) of high-beta (β) plasma events (defined here as β > 1) as measured by the RBSPICE instrument in the ˜45 keV to ˜600 keV proton energy range in the inner magnetosphere (L hours. While most of these events have a β less than 2, there are a number of observations reaching β greater than 4. Other observations of particular note are high-β events during relatively minor geomagnetic storms and examples of very long duration high-β plasmas. We show that high-β plasmas are a relatively common occurrence in the inner magnetosphere during both quiet and active times. As such, the waves generated by these plasmas may have an underappreciated role in the inner magnetosphere, and thus the study of these plasmas and their instabilities may be more important than has been currently addressed.

  7. Shapes of Energetic Ion Spectra in Saturn's Magnetosphere Compared with those at Earth and Jupiter

    Science.gov (United States)

    Hamilton, D. C.; Mitchell, D. G.; Krimigis, S. M.

    2013-12-01

    Saturn's magnetosphere contains suprathermal and energetic ions that originate from a number of plasma sources including Enceladus, Titan, Saturn's atmosphere and ionosphere and the solar wind, with internal sources dominating. Although different species originate at different locations, transport processes and acceleration during or after transport distribute the energetic ions throughout the magnetosphere out to the magnetopause. In principle, the shapes of the energy spectra of these ions contain information on acceleration processes. However, because outside of about 9 RS long-term average spectra of all species are quite good power laws, it is difficult to pick one energy parameter (e.g., energy/charge or energy/nucleon) as better organizing the spectra by, for example, maintaining constant abundance ratios from low to high energies. Inside of 9 RS there are energy-dependent losses that alter the spectra but aren't directly related to acceleration. Here, using data from the Cassini/CHEMS sensor, we investigate ion spectra over the energy per charge range 3-220 keV/e in more detail with better resolution in both space and time, looking for evidence of spectral differences among species based on charge (e.g., O+ vs. O++) or plasma source (e.g., O+ (Enceladus) vs. He++ (solar wind)). We will compare Saturn's ion spectra with those from the magnetospheres of Earth and Jupiter and discuss implications for acceleration processes.

  8. Earth's magnetosphere and outer radiation belt under sub-Alfvénic solar wind.

    Science.gov (United States)

    Lugaz, Noé; Farrugia, Charles J; Huang, Chia-Lin; Winslow, Reka M; Spence, Harlan E; Schwadron, Nathan A

    2016-10-03

    The interaction between Earth's magnetic field and the solar wind results in the formation of a collisionless bow shock 60,000-100,000 km upstream of our planet, as long as the solar wind fast magnetosonic Mach (hereafter Mach) number exceeds unity. Here, we present one of those extremely rare instances, when the solar wind Mach number reached steady values solar wind-magnetosphere coupling which is unusual for planets in our solar system but may be common for close-in extrasolar planets.

  9. The Effects of Abrupt Wind Shears in the Solar Wind on the Earth's Magnetosphere

    Science.gov (United States)

    Borovsky, J.; Boudouridis, A.; Birn, J.; Denton, M.

    2014-12-01

    The solar wind is filled sudden velocity shears. The shears take the form of vorticity layers co-located with current sheets. The velocity vector makes its change in a few seconds. For shear layers with vector velocity changes greater than 50 km/s, an average of 12 shear layers pass the Earth per day. Global magnetospheric MHD simulations with four different simulation codes have been performed at the Community Coordinated Modeling Center (CCMC) to examine the reaction of the Earth to the solar-wind velocity shears. All 4 simulation codes predict comet-like disconnections of the magnetotail, the magnetosheath, and the bow shock on the flanks as a shear layer passes the Earth. The simulation codes also predict sudden changes in the cross-polar-cap potential and ionospheric Joule dissipation as the shear layers pass the Earth. A data-analysis research effort is underway to look for signatures of the Earth's reaction to abrupt wind shear events; preliminary results of that effort will be discussed.

  10. Biogenic oxygen from Earth transported to the Moon by a wind of magnetospheric ions

    Science.gov (United States)

    Terada, Kentaro; Yokota, Shoichiro; Saito, Yoshifumi; Kitamura, Naritoshi; Asamura, Kazushi; Nishino, Masaki N.

    2017-01-01

    For five days of each lunar orbit, the Moon is shielded from solar wind bombardment by the Earth's magnetosphere, which is filled with terrestrial ions. Although the possibility of the presence of terrestrial nitrogen and noble gases in lunar soil has been discussed based on their isotopic composition 1 , complicated oxygen isotope fractionation in lunar metal 2,3 (particularly the provenance of a 16O-poor component) re­mains an enigma 4,5 . Here, we report observations from the Japanese spacecraft Kaguya of significant numbers of 1-10 keV O+ ions, seen only when the Moon was in the Earth's plasma sheet. Considering the penetration depth into metal of O+ ions with such energy, and the 16O-poor mass-independent fractionation of the Earth's upper atmosphere 6 , we conclude that biogenic terrestrial oxygen has been transported to the Moon by the Earth wind (at least 2.6 × 104 ions cm‑2 s‑1) and implanted into the surface of the lunar regolith, at around tens of nanometres in depth 3,4 . We suggest the possibility that the Earth's atmosphere of billions of years ago may be preserved on the present-day lunar surface.

  11. Ion Acceleration at Earth, Saturn and Jupiter and its Global Impact on Magnetospheric Structure

    Science.gov (United States)

    Brandt, Pontus

    2016-07-01

    The ion plasma pressures at Earth, Saturn and Jupiter are significant players in the electrodynamic force-balance that governs the structure and dynamics of these magnetospheres. There are many similarities between the physical mechanisms that are thought to heat the ion plasma to temperatures that even exceed those of the solar corona. In this presentation we compare the ion acceleration mechanisms at the three planetary magnetospheres and discuss their global impacts on magnetopsheric structure. At Earth, bursty-bulk flows, or "bubbles", have been shown to accelerate protons and O+ to high energies by the earthward moving magnetic dipolarization fronts. O+ ions display a more non-adiabatic energization in response to these fronts than protons do as they are energized and transported in to the ring-current region where they reach energies of several 100's keV. We present both in-situ measurements from the NASA Van Allen Probes Mission and global Energetic Neutral (ENA) images from the High-Energy Neutral Atom (HENA) Camera on board the IMAGE Mission, that illustrate these processes. The global impact on the magnetospheric structure is explored by comparing the empirical magnetic field model TS07d for given driving conditions with global plasma pressure distributions derived from the HENA images. At Saturn, quasi-periodic energization events, or large-scale injections, occur beyond about 9 RS around the post-midnight sector, clearly shown by the Ion and Neutral Atom Camera (INCA) on board the Cassini mission. In contrast to Earth, the corotational drift dominates even the energetic ion distributions. The large-scale injections display similar dipolarization front features can be found and there are indications that like at Earth the O+ responds more non-adiabatically than protons do. However, at Saturn there are also differences in that there appears to be energization events deep in the inner magnetosphere (6-9 RS) preferentially occurring in the pre

  12. Magnetic turbulence in space plasmas: in and around the Earth's magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Zimbardo, Gaetano [Universita della Calabria, Dipartimento di Fisica, Ponte P. Bucci, Cubo 31C, I-87036 Arcavacata di Rende (Italy)

    2006-12-15

    In collisionless space plasmas most phenomena are governed by wave particle interaction and by the interaction with the large scale fields. Low frequency magnetic turbulence in the solar wind is relatively well characterized and understood. The situation is more complicated for magnetic turbulence in and around the Earth's magnetosphere, where the turbulence feature can vary widely with the location. Recent spacecraft observations of magnetic turbulence in the magnetosheath, in the polar cusp regions and in the magnetotail are considered. Turbulence features like the fluctuation level, the spectral power law index, the turbulence drivers and the turbulence anisotropy and intermittency are addressed. The influence of such a turbulence on the plasma transport and dynamics is briefly described, also using the results of numerical simulations.

  13. Intermittency of the turbulent processes in the Earth's magnetosphere detected from the ground-based measurements

    Science.gov (United States)

    Stepanova, Marina; Foppiano, Alberto; Ovalle, Elias; Antonova, Elizavieta; Troshichev, Oleg

    2008-11-01

    Turbulent processes in the Earth's magnetosphere are reflected in the dynamical behavior of the geomagnetic indices and other parameters determined from ground based observations. Intermittent properties of one minute Polar Cap (PC) index and auroral radio wave absorption are studied using 1995-2000 data sets. It was found that the probability distribution functions (PDFs) of both PC-index and absorption fluctuations display a strong non-Gaussian shape. This indicates that they are not characterized by a global time self-similarity but rather exhibit intermittency, as previously reported for solar wind velocity and auroral electrojet index values. In the case of the auroral absorption it was also found that intermittency strongly depends on the magnetic local time, being largest in the nighttime sector. This shows that the acceleration of precipitating particles is intermittent, especially near the substorm eye, where the level of turbulence increases. Application of the Local Intermittency Measure (LIM) technique confirms the aforementioned results to a better precision.

  14. Interaction between an interplanetary magnetic cloud and the Earth's magnetosphere: Motions of the bow shock

    Science.gov (United States)

    Wu, D. J.; Chao, J. K.; Lepping, R. P.

    2000-06-01

    An interplanetary magnetic cloud (IMC) is an important solar-terrestrial connection event. It is an ideal object for the study of solar-terrestrial relations and space weather because the Earth's space environment can be affected considerably during an IMC passage. An IMC was observed to pass the Earth during October 18-20, 1995. Wind recorded its interplanetary characteristics at ~175RE upstream of the Earth's bow shock, and ~45 min later, Geotail, being near the nominal location of the dawn bow shock, detected IMC-related multiple bow shock crossings. Using simultaneous measurements from Wind and Geotail, we analyzed, with a semiempirical bow shock model with two parameters, the bow shock motion caused by the interaction of the IMC with the magnetosphere during the passage. We also compared the bow shock motion predicted by the model, and hence the predicted Geotail bow shock crossings, with Geotail observations of the actual crossings. The results showed that the observed multiple bow shock crossings, which were obviously due to temporal variations of the upstream solar wind, can be well explained by the model-predicted bow shock motion.

  15. Solar wind dependence of ion parameters in the Earth's magnetospheric region calculated from CLUSTER observations

    Directory of Open Access Journals (Sweden)

    M. H. Denton

    2008-03-01

    Full Text Available Moments calculated from the ion distributions (~0–40 keV measured by the Cluster Ion Spectrometry (CIS instrument are combined with data from the Cluster Flux Gate Magnetometer (FGM instrument and used to characterise the bulk properties of the plasma in the near-Earth magnetosphere over five years (2001–2005. Results are presented in the form of 2-D xy, xz and yz GSM cuts through the magnetosphere using data obtained from the Cluster Science Data System (CSDS and the Cluster Active Archive (CAA. Analysis reveals the distribution of ~0–40 keV ions in the inner magnetosphere is highly ordered and highly responsive to changes in solar wind velocity. Specifically, elevations in temperature are found to occur across the entire nightside plasma sheet region during times of fast solar wind. We demonstrate that the nightside plasma sheet ion temperature at a downtail distance of ~12 to 19 Earth radii increases by a factor of ~2 during periods of fast solar wind (500–1000 km s−1 compared to periods of slow solar wind (100–400 km s−1. The spatial extent of these increases are shown in the xy, xz and yz GSM planes. The results from the study have implications for modelling studies and simulations of solar-wind/magnetosphere coupling, which ultimately rely on in situ observations of the plasma sheet properties for input/boundary conditions.

  16. Investigation of the Transport of Solar Ions Through the Earth's Magnetosphere

    Science.gov (United States)

    Lennartsson, O. W.; Evans, David (Technical Monitor)

    2000-01-01

    The objective of this study has been to infer, by statistical means, the most probable mode of entry of solar wind plasma into Earth's magnetotail, using a particular set of archived data from the Lockheed Plasma Composition Experiment on the International Sun-Earth Explorer One (ISEE-1) satellite, jointly sponsored by the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) in the 1970's and 80's. Despite their considerable age, the Lockheed ISEE-1 data are still, at the time of this report, the only substantial ion composition data in the sub-keV to keV energy range available from the magnetotail beyond 9 R(sub E), because of various technical problems with ion mass spectrometers on later missions, and are therefore a unique source of information about the mixing of solar and terrestrial origin plasmas in the tail, within the ISEE-1 apogee of almost 23 R(sub E). The entire set of archived data used in this study, covering the 4.5 years of operation of the instrument and comprising not only tail measurements but also data from the inner magnetosphere as well as data from outside the magnetopause, is now available to the public via the WorldWideWeb at the address: http://cis.spasci.com/ISEE_ions The fundamental assumption of this and other studies of magnetosphere ion composition is that He++ and O+ ions are virtually certain "tags" of solar and terrestrial origins, respectively. This is an assumption with strong theoretical basis and it is corroborated by observational evidence, including the often substantial differences between the velocity distribution functions of those two species. The H+ ions can have a dual origin, in principle, but the close resemblance in the ISEE-1 data between the dynamics of H+ and He++ ions indicates a predominantly solar origin of the H+ ions in the tail, at least. By the same token, the usually minor He+ ions are probably almost entirely of terrestrial origin, because of their similarity to the O

  17. Investigation of the Transport of Solar Ions Through the Earth's Magnetosphere

    Science.gov (United States)

    Lennartsson, O. W.

    2000-08-01

    The objective of this study has been to infer, by statistical means, the most probable mode of entry of solar wind plasma into Earth's magnetotail, using a particular set of archived data from the Lockheed Plasma Composition Experiment on the International Sun-Earth Explorer One (ISEE-1) satellite, jointly sponsored by the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) in the 1970's and 80's. Despite their considerable age, the Lockheed ISEE-1 data are still, at the time of this report, the only substantial ion composition data in the sub-keV to keV energy range available from the magnetotail beyond 9 RE, because of various technical problems with ion mass spectrometers on later missions, and are therefore a unique source of information about the mixing of solar and terrestrial origin plasmas in the tail, within the ISEE-1 apogee of almost 23 RE. The entire set of archived data used in this study, covering the 4.5 years of operation of the instrument and comprising not only tail measurements but also data from the inner magnetosphere as well as data from outside the magnetopause, is now available to the public via the WorldWideWeb at the address: http://cis.spasci.com/ISEE_ions The fundamental assumption of this and other studies of magnetosphere ion composition is that He++ and O+ ions are virtually certain "tags" of solar and terrestrial origins, respectively. This is an assumption with strong theoretical basis and it is corroborated by observational evidence, including the often substantial differences between the velocity distribution functions of those two species. The H+ ions can have a dual origin, in principle, but the close resemblance in the ISEE-1 data between the dynamics of H+ and He++ ions indicates a predominantly solar origin of the H+ ions in the tail, at least. By the same token, the usually minor He+ ions are probably almost entirely of terrestrial origin, because of their similarity to the O+ ions.

  18. Spacecraft plume interactions with the magnetosphere plasma environment in geostationary Earth orbit

    Science.gov (United States)

    Stephani, K. A.; Boyd, I. D.

    2016-02-01

    Particle-based kinetic simulations of steady and unsteady hydrazine chemical rocket plumes are presented in a study of plume interactions with the ambient magnetosphere in geostationary Earth orbit. The hydrazine chemical rocket plume expands into a near-vacuum plasma environment, requiring the use of a combined direct simulation Monte Carlo/particle-in-cell methodology for the rarefied plasma conditions. Detailed total and differential cross sections are employed to characterize the charge exchange reactions between the neutral hydrazine plume mixture and the ambient hydrogen ions, and ion production is also modeled for photoionization processes. These ionization processes lead to an increase in local plasma density surrounding the spacecraft owing to a partial ionization of the relatively high-density hydrazine plume. Results from the steady plume simulations indicate that the formation of the hydrazine ion plume are driven by several competing mechanisms, including (1) local depletion and (2) replenishing of ambient H+ ions by charge exchange and thermal motion of 1 keV H+ from the ambient reservoir, respectively, and (3) photoionization processes. The self-consistent electrostatic field forces and the geostationary magnetic field have only a small influence on the dynamics of the ion plume. The unsteady plume simulations show a variation in neutral and ion plume dissipation times consistent with the variation in relative diffusion rates of the chemical species, with full H2 dissipation (below the ambient number density levels) approximately 33 s after a 2 s thruster burn.

  19. Data-based modelling of the Earth's dynamic magnetosphere: a review

    Directory of Open Access Journals (Sweden)

    N. A. Tsyganenko

    2013-10-01

    Full Text Available This paper reviews the main advances in the area of data-based modelling of the Earth's distant magnetic field achieved during the last two decades. The essence and the principal goal of the approach is to extract maximum information from available data, using physically realistic and flexible mathematical structures, parameterized by the most relevant and routinely accessible observables. Accordingly, the paper concentrates on three aspects of the modelling: (i mathematical methods to develop a computational "skeleton" of a model, (ii spacecraft databases, and (iii parameterization of the magnetospheric models by the solar wind drivers and/or ground-based indices. The review is followed by a discussion of the main issues concerning further progress in the area, in particular, methods to assess the models' performance and the accuracy of the field line mapping. The material presented in the paper is organized along the lines of the author Julius-Bartels' Medal Lecture during the General Assembly 2013 of the European Geosciences Union.

  20. Statistical analysis of the magnetic fluctuations in boundary layers of Earth's magnetosphere

    Science.gov (United States)

    Kozak, L. V.; Prokhorenkov, A. S.; Savin, S. P.

    2015-11-01

    Investigation of statistical features of the magnetic fluctuations in boundary layers of Earth's magnetosphere and plasma of the solar wind, on different time scales, is carried out using magnetic field measurements from Cluster-II with a sampling frequency of 22.5 Hz in 2007-2010. We have studied the changes of shape and parameters of probability density function for magnetic fluctuations in the solar wind, foreshock region, postshock region and magnetosheath. In particular, the evolution of maximum of probability density function and the structure functions of different orders as characteristics of turbulent processes for different time scales are investigated. Structure functions of high orders are used to determine the character of turbulent processes and the resulting diffusion in these regions. We have found that the highest intermittency is observed in the postshock region. Furthermore, magnetic turbulence in the middle magnetosheath corresponds to log-Poisson turbulent cascade model, and that in the SW plasma conforms to the Iroshnikov-Kraichnan's model.

  1. Data-based modelling of the Earth's dynamic magnetosphere: a review

    Science.gov (United States)

    Tsyganenko, N. A.

    2013-10-01

    This paper reviews the main advances in the area of data-based modelling of the Earth's distant magnetic field achieved during the last two decades. The essence and the principal goal of the approach is to extract maximum information from available data, using physically realistic and flexible mathematical structures, parameterized by the most relevant and routinely accessible observables. Accordingly, the paper concentrates on three aspects of the modelling: (i) mathematical methods to develop a computational "skeleton" of a model, (ii) spacecraft databases, and (iii) parameterization of the magnetospheric models by the solar wind drivers and/or ground-based indices. The review is followed by a discussion of the main issues concerning further progress in the area, in particular, methods to assess the models' performance and the accuracy of the field line mapping. The material presented in the paper is organized along the lines of the author Julius-Bartels' Medal Lecture during the General Assembly 2013 of the European Geosciences Union.

  2. Generation of Multiband Chorus in the Earth's Magnetosphere: 1-D PIC Simulation

    Science.gov (United States)

    Gao, Xinliang; Ke, Yangguang; Lu, Quanming; Chen, Lunjin; Wang, Shui

    2017-01-01

    Multiband chorus waves, where the frequency of upper band chorus is about twice that of lower band chorus, have recently been reported based on THEMIS observations. The generation of multiband chorus waves is attributed to the mechanism of lower band cascade, where upper band chorus is excited via the nonlinear coupling process between lower band chorus and the associated density mode with the frequency equal to that of lower band chorus. In this letter, with a one-dimensional (1-D) particle-in-cell (PIC) simulation model, we have successfully reproduced multiband chorus waves. During the simulation, the significant density fluctuation is driven by the fluctuating electric field along the wave vector of the pump wave (lower band chorus), which can be directly observed in this self-consistent plasma system. Then, the second harmonic of the pump whistler-mode wave (upper band chorus) is generated. After quantitatively analyzing resonant conditions among wave numbers, we can confirm that the generation is caused due to the coupling between the pump wave and the density fluctuation along its wave vector. The third harmonic can also be excited through lower band cascade if the pump whistler-mode wave has a sufficiently large amplitude. Our simulation results not only provide a theoretical support to the mechanism of lower band cascade to generate multiband chorus but also propose a new pattern of evolution for whistler-mode waves in the Earth's magnetosphere.

  3. ISEE-3 observations of the earth's radio continuum through the bow shock and magnetosheath and in the magnetosphere

    Science.gov (United States)

    Steinberg, J.-L.; Hoang, S.; Lacombe, C.; Zwickl, R. D.

    1988-01-01

    On October 1 1983, ISEE-3 crossed the earth's bow shock several times and entered the magnetosphere while continuously recording the nonthermal continuum (NTC) radio emission which is generated inside the magnetosphere. The effects of the solar wind, the bow shock, the magnetosheath, and the magnetopause on the propagation of the NTC are studied. On that day it is found that: (1) the relative values of the NTC low frequency cut-off in the solar wind and in the magnetosheath is due to an unusually high density overshoot in the bow shock, 7 to 11 times the solar wind density; (2) refraction at the interface between the magnetosheath and the solar wind can explain most of the decrease in the source angular size when the observer travels away from the earth; (3) plasma density irregularities in the magnetosheath cause considerable scattering of the NTC, and this effect gives a large apparent size to the NTC source when observed from inside the magnetosheath; and (4) the apparent source is also relatively large inside the magnetosphere, probably due to an approach to ray isotropy caused by oblique reflections from the magnetopause.

  4. Cluster observations of near-Earth magnetospheric lobe plasma densities – a statistical study

    Directory of Open Access Journals (Sweden)

    K. R. Svenes

    2008-09-01

    Full Text Available The Cluster-mission has enabled a study of the near-Earth magnetospheric lobes throughout the waning part of solar cycle 23. During the first seven years of the mission the satellites crossed this region of space regularly from about July to October. We have obtained new and more accurate plasma densities in this region based on spacecraft potential measurements from the EFW-instrument. The plasma density measurements are found by converting the potential measurements using a functional relationship between these two parameters. Our observations have shown that throughout this period a full two thirds of the measurements were contained in the range 0.007–0.092 cm−3 irrespective of solar wind conditions or geomagnetic activity. In fact, the most probable density encountered was 0.047 cm−3, staying roughly constant throughout the entire observation period. The plasma population in this region seems to reflect an equilibrium situation in which the density is independent of the solar wind condition or geomagnetic activity. However, the high density tail of the population (ne>0.2 cm−3 seemed to decrease with the waning solar cycle. This points to a source region influenced by the diminishing solar UV/EUV-intensity. Noting that the quiet time polar wind has just such a development and that it is magnetically coupled to the lobes, it seems likely to assume that this is a prominent source for the lobe plasma.

  5. Role of finite ionospheric conductivity on toroidal field line oscillations in the Earth's magnetosphere -- Analytic solutions

    Science.gov (United States)

    Bulusu, Jayashree; Sinha, A. K.; Vichare, Geeta

    2016-06-01

    An analytic solution has been formulated to study the role of ionospheric conductivity on toroidal field line oscillations in the Earth's magnetosphere. The effect of ionospheric conductivity is addressed in two limits, viz, (a) when conductance of Alfvén wave is much different from ionospheric Pedersen conductance and (b) when conductance of Alfvén wave is close to the ionospheric Pedersen conductance. In the former case, the damping is not significant and standing wave structures are formed. However, in the latter case, the damping is significant leading to mode translation. Conventionally, "rigid-end" and "free-end" cases refer to eigenstructures for infinitely large and vanishingly small limit of ionospheric conductivity, respectively. The present work shows that when the Pedersen conductance overshoots (undershoots) the Alfvén wave conductance, a free-end (rigid-end) mode gets transformed to rigid-end (free-end) mode with an increase (decrease) in harmonic number. This transformation takes place within a small interval of ionospheric Pedersen conductance around Alfvén wave conductance, beyond which the effect of conductivity on eigenstructures of field line oscillations is small. This regime of conductivity limit (the difference between upper and lower limits of the interval) decreases with increase in harmonic number. Present paper evaluates the damping effect for density index other than the standard density index m = 6, using perturbation technique. It is found that for a small departure from m = 6, both mode frequency and damping rate become a function of Pedersen conductivity.

  6. Global effects of transmitted shock wave propagation through the Earth's inner magnetosphere: First results from 3-D hybrid kinetic modeling

    Science.gov (United States)

    Lipatov, A. S.; Sibeck, D. G.

    2016-09-01

    We use a new hybrid kinetic model to simulate the response of ring current, outer radiation belt, and plasmaspheric particle populations to impulsive interplanetary shocks. Since particle distributions attending the interplanetary shock waves and in the ring current and radiation belts are non-Maxwellian, wave-particle interactions play a crucial role in energy transport within the inner magnetosphere. Finite gyroradius effects become important in mass loading the shock waves with the background plasma in the presence of higher energy ring current and radiation belt ions and electrons. Initial results show that shocks cause strong deformations in the global structure of the ring current, radiation belt, and plasmasphere. The ion velocity distribution functions at the shock front, in the ring current, and in the radiation belt help us determine energy transport through the Earth's inner magnetosphere.

  7. Near-Earth Magnetic Field Effects of Large-Scale Magnetospheric Currents

    DEFF Research Database (Denmark)

    Lühr, Hermann; Xiong, Chao; Olsen, Nils

    2016-01-01

    . Significant progress in interpreting the magnetic fields from the different sources has been achieved thanks to magnetic satellite missions like Ørsted, CHAMP and now Swarm. Of particular interest for this article is a proper representation of the magnetospheric ring current effect. Uncertainties in modelling...... in the magnetospheric tail. Also their magnetic contribution at LEO orbits is non-negligible. Treating them as an independent source is a more recent development, which has cured some of the problems in geomagnetic field modelling. Unfortunately there is no index available for characterising the tail current intensity...

  8. Alfvén wings at Earth's magnetosphere under strong interplanetary magnetic fields

    Directory of Open Access Journals (Sweden)

    A. J. Ridley

    2007-03-01

    Full Text Available A number of recent studies have shown that the upstream Mach number may play a significant role in the energy transfer between the solar wind and the magnetosphere. Magnetohydrodynamic (MHD simulation results of the magnetosphere-ionosphere system are presented that show the transition from nominal solar wind and interplanetary magnetic field driving to extremely strong driving. One of the predominant features of the magnetosphere that becomes apparent during low Mach number conditions is the formation of Alfvén wings above and below the magnetosphere. Alfvén wing are cavities of low flow, and have been observed at Io and Ganymede, both of which reside in regions of sub-Alfvénic flow. It is shown that Alfvén wings exist even during nominal Mach number time periods – the wings fold over to form what has been classically viewed as the magnetotail. The regions of low flow within the Alfvén wing limit the electric field applied across the ionosphere, hence causing the ionospheric cross polar cap potential to be dependent upon the Mach number, and in turn, causing the saturation of the potential.

  9. The Level of Turbulence in the Solar Wind and the Driving of the Earth's Magnetosphere

    Science.gov (United States)

    Borovsky, J. E.; Gosling, J. T.

    2001-05-01

    Times when the level of magnetic-field fluctuations in the solar wind are very small (IMF calm) are compared with "normal" times (IMF noisy). Using ISEE-3 and ISEE-2 data, for a given value of solar-wind vBz, it is found that the auroral electrojet indices AE, AU, and AL and the planetary index KP are substantial reduced in magnitude when the IMF is calm. This is particularly true for times when the IMF Bz is northward. An analogy is explored between the solar-wind-driven magnetosphere and laboratory fluid-flow experiments in which the drag on an obstacle in the flow and the structure of the fluid wake behind the obstacle are varied by injecting turbulence of various amplitudes in the upstream fluid. The laboratory results are explained with the concept that turbulent eddy viscosity, which is a function of the turbulence amplitude, controls the coupling of the fluid to the obstacle. This eddy-viscosity-coupling concept is explored for the solar-wind driving the magnetosphere via the magnetosheath. A clue as to why SMCs (steady magnetospheric convection events) occur may be uncovered.

  10. Oxygen and hydrogen ion abundance in the near-Earth magnetosphere: Statistical results on the response to the geomagnetic and solar wind activity conditions

    CERN Document Server

    Kronberg, Elena A; Daly, Patrick W; Grigorenko, Elena E; Kistler, Lynn; Fränz, Markus; Dandouras, Iannis

    2012-01-01

    The composition of ions plays a crucial role for the fundamental plasma properties in the terrestrial magnetosphere. We investigate the oxygen-to-hydrogen ratio in the near-Earth magnetosphere from -10 RE274 keV O+ ion intensities, relative to the corresponding hydrogen intensities; (3) In contrast to ~10 keV ions, the >274 keV O+ ions show the strongest acceleration during growth phase and not during the expansion phase itself. This suggests a connection between the energy input to the magnetosphere and the effective energization of energetic ions during growth phase; (4) The ratio between quiet and disturbed times for the intensities of ion ionospheric outflow is similar to those observed in the near-Earth magnetosphere at >274 keV. Therefore, the increase of the energetic ion intensity during disturbed time is more likely due to the intensification than to the more effective acceleration of the ionospheric source. In conclusion, the energization process in the near-Earth magnetosphere is mass dependent and...

  11. Distortions of the magnetic field by storm-time current systems in Earth's magnetosphere

    Directory of Open Access Journals (Sweden)

    N. Yu. Ganushkina

    2010-01-01

    Full Text Available Magnetic field and current system changes in Earth's inner magnetosphere during storm times are studied using two principally different modeling approaches: on one hand, the event-oriented empirical magnetic field model, and, on the other, the Space Weather Modeling Framework (SWMF built around a global MHD simulation. Two storm events, one moderate storm on 6–7 November 1997 with Dst minimum about −120 nT and one intense storm on 21–23 October 1999 with Dst minimum about −250 nT were modeled. Both modeling approaches predicted a large ring current (first partial, later symmetric contribution to the magnetic field perturbation for the intense storm. For the moderate storm, the tail current plays a dominant role in the event-oriented model results, while the SWMF results showed no strong tail current in the main phase, which resulted in a poorly timed storm peak relative to the observations. These results imply that the the development of a ring current depends on a strong force to inject the particles deep into the inner magnetosphere, and that the tail current is an important external source for the distortions of the inner magnetospheric magnetic field for both storms. Neither modeling approach was able to reproduce all the variations in the Bx and By components observed at geostationary orbit by GOES satellites during these two storms: the magnetopause current intensifications are inadequate, and the field-aligned currents are not sufficiently represented. While the event-oriented model reproduces rather well the Bz component at geostationary orbit, including the substorm-associated changes, the SWMF field is too dipolar at these locations. The empirical model is a useful tool for validation of the first-principle based models such as the SWMF.

  12. Crossover behavior of multiscale fluctuations in Big Data: Langevin model and substorm time-scales in Earth's magnetosphere

    Science.gov (United States)

    Sharma, A. S.; Setty, V. A.

    2015-12-01

    Multiscale fluctuations in large and complex data are usually characterized by a power law with a scaling exponent but many systems require more than one exponent and thus exhibit crossover behavior. The scaling exponents, such as Hurst exponents, represent the nature of correlation in the system and the crossover shows the presence of more than one type of correlation. An accurate characterization of the crossover behavior is thus needed for a better understanding of the inherent correlations in the system, and is an important method of Big Data analysis. A multi-step process is developed for accurate computation of the crossover behavior. First the detrended fluctuation analysis is used to remove the trends in the data and the scaling exponents are computed. The crossover point is then computed by a Hyperbolic regression technique, with no prior assumptions. The time series data of the magnetic field variations during substorms in the Earth's magnetosphere is analyzed with these techniques and yields a crossover behavior with a time scale of ~4 hrs. A Langevin model derived from the data provides an excellent fit to the crossover in the scaling exponents and a good model of magnetospheric dynamics. The combination of fluctuation analysis and mathematical modeling thus yields a comprehensive approach in the analysis of Big Data.

  13. Hydrogen and helium isotope inner radiation belts in the Earth's magnetosphere

    Directory of Open Access Journals (Sweden)

    G. I. Pugacheva

    Full Text Available Radial transport theory for inner radiation zone MeV ions has been extended by combining radial diffusive transport and losses due to Coulomb friction with local generation of D, T and 3He ions from nuclear reactions taking place on the inner edge of the inner radiation zone. Based on interactions between high energy trapped protons and upper atmospheric constituents we have included a nuclear reaction yield D, T and 3He flux source that was numerically derived from a nuclear reaction model code originally developed at the Institute of Nuclear Researches in Moscow, Russia. Magnetospheric transport computations have been made covering the L-shell range L=1.0–1.6. The resulting MeV energy D, T and 3He ion flux distributions show a strong influence of the local nuclear source mechanism on the inner zone energetic D, T and 3He ion content.

    Key words: Atmospheric composition and structure (Thermosphere-composition and chemistry · Magnetospheric physics (Energetic particles · trapped.

  14. Instrument technology for magnetosphere plasma imaging from high Earth orbit. Design of a radio plasma sounder

    Science.gov (United States)

    Haines, D. Mark; Reinisch, Bodo W.

    1995-01-01

    The use of radio sounding techniques for the study of the ionospheric plasma dates back to G. Briet and M. A. Tuve in 1926. Ground based swept frequency sounders can monitor the electron number density (N(sub e)) as a function of height (the N(sub e) profile). These early instruments evolved into a global network that produced high-resolution displays of echo time delay vs frequency on 35-mm film. These instruments provided the foundation for the success of the International Geophysical Year (1958). The Alouette and International Satellites for Ionospheric Studies (ISIS) programs pioneered the used of spaceborne, swept frequency sounders to obtain N(sub e) profiles of the topside of the ionosphere, from a position above the electron density maximum. Repeated measurements during the orbit produced an orbital plane contour which routinely provided density measurements to within 10%. The Alouette/ISIS experience also showed that even with a high powered transmitter (compared to the low power sounder possible today) a radio sounder can be compatible with other imaging instruments on the same satellite. Digital technology was used on later spacecraft developed by the Japanese (the EXOS C and D) and the Soviets (Intercosmos 19 and Cosmos 1809). However, a full coherent pulse compression and spectral integrating capability, such as exist today for ground-based sounders (Reinisch et al., 1992), has never been put into space. NASA's 1990 Space Physics Strategy Implementation Study "The NASA Space Physics Program from 1995 to 2010" suggested using radio sounders to study the plasmasphere and the magnetopause and its boundary layers (Green and Fung, 1993). Both the magnetopause and plasmasphere, as well as the cusp and boundary layers, can be observed by a radio sounder in a high-inclination polar orbit with an apogee greater than 6 R(sub e) (Reiff et al., 1994; Calvert et al., 1995). Magnetospheric radio sounding from space will provide remote density measurements of

  15. Cetacean beachings correlate with geomagnetic disturbances in Earth's magnetosphere: an example of how astronomical changes impact the future of life

    Science.gov (United States)

    Ferrari, Thomas E.

    2017-04-01

    The beaching and stranding of whales and dolphins around the world has been mystifying scientists for centuries. Although many theories have been proposed, few are substantiated by unequivocal statistical evidence. Advances in the field of animal magnetoreception have established that many organisms, including cetaceans, have an internal `compass,' which they use for orientation when traveling long distances. Astrobiology involves not only the origin and distribution of life in the universe, but also the scientific study of how extraterrestrial conditions affect evolution of life on planet Earth. The focus of this study is how cetacean life is influenced by disturbances in its environment that originate from an astrological phenomenon - in the present study that involves solar flares and cetacean beachings. Solar storms are caused by major coronal eruptions on the Sun. Upon reaching Earth, they cause disturbances in Earth's normally stable magnetosphere. Unable to follow an accurate magnetic bearing under such circumstances, cetaceans lose their compass reading while travelling and, depending on their juxtaposition and nearness to land, eventually beach themselves. (1) This hypothesis was supported by six separate, independent surveys of beachings: (A) in the Mediterranean Sea, (B) the northern Gulf of Mexico, (C) the east and (D) west coasts of the USA and two surveys (E and F) from around the world. When the six surveys were pooled (1614 strandings), a highly significant correlation (R 2 = 0.981) of when strandings occurred with when major geomagnetic disturbances in Earth's magnetosphere occurred was consistent with this hypothesis. (2) Whale and dolphin strandings in the northern Gulf of Mexico and the east coast of the USA were correlated (R 2 = 0.919, R 2 = 0.924) with the number of days before and after a geomagnetic storm. (3) Yearly strandings were correlated with annual geomagnetic storm days. (4) Annual beachings of cetaceans from 1998 to 2012 were

  16. Characteristics of VLF wave propagation in the Earth's magnetosphere in the presence of an artificial density duct

    Science.gov (United States)

    Pasmanik, Dmitry; Demekhov, Andrei

    We study the propagation of VLF waves in the Earth's ionosphere and magnetosphere in the presence of large-scale artificial plasma inhomogeneities which can be created by HF heating facilities like HAARP and ``Sura''. A region with enhanced cold plasma density can be formed due to the action of HF heating. This region is extended along geomagnetic field (up to altitudes of several thousand km) and has rather small size across magnetic field (about 1 degree). The geometric-optical approximation is used to study wave propagation. The plasma density and ion composition are calculated with the use of SAMI2 model, which was modified to take the effect of HF heating into account. We calculate ray trajectories of waves with different initial frequency and wave-normal angles and originating at altitudes of about 100 km in the region near the heating area. The source of such waves could be the lightning discharges, modulated HF heating of the ionosphere, or VLF transmitters. Variation of the wave amplitude along the ray trajectories due to refraction is considered and spatial distribution of wave intensity in the magnetosphere is analyzed. We show that the presence of such a density disturbances can lead to significant changes of wave propagation trajectories, in particular, to efficient guiding of VLF waves in this region. This can result in a drastic increase of the VLF-wave intensity in the density duct. The dependence of wave propagation properties on parameters of heating facility operation regime is considered. We study the variation of the spatial distribution of VLF wave intensity related to the slow evolution of the artificial inhomogeneity during the heating.

  17. Satellite and Ground Signatures of Kinetic and Inertial Scale ULF Alfven Waves Propagating in Warm Plasma in Earth's Magnetosphere

    Science.gov (United States)

    Rankin, R.; Sydorenko, D.

    2015-12-01

    Results from a 3D global numerical model of Alfven wave propagation in a warm multi-species plasma in Earth's magnetosphere are presented. The model uses spherical coordinates, accounts for a non-dipole magnetic field, vertical structure of the ionosphere, and an air gap below the ionosphere. A realistic density model is used. Below the exobase altitude (2000 km) the densities and the temperatures of electrons, ions, and neutrals are obtained from the IRI and MSIS models. Above the exobase, ballistic (originating from the ionosphere and returning to ionosphere) and trapped (bouncing between two reflection points above the ionosphere) electron populations are considered similar to [Pierrard and Stegen (2008), JGR, v.113, A10209]. Plasma parameters at the exobase provided by the IRI are the boundary conditions for the ballistic electrons while the [Carpenter and Anderson (1992), JGR, v.97, p.1097] model of equatorial electron density defines parameters of the trapped electron population. In the simulations that are presented, Alfven waves with frequencies from 1 Hz to 0.01 Hz and finite azimuthal wavenumbers are excited in the magnetosphere and compared with Van Allen Probes data and ground-based observations from the CARISMA array of ground magnetometers. When short perpendicular scale waves reflect form the ionosphere, compressional Alfven waves are observed to propagate across the geomagnetic field in the ionospheric waveguide [e.g., Lysak (1999), JGR, v.104, p.10017]. Signals produced by the waves on the ground are discussed. The wave model is also applied to interpret recent Van Allen Probes observations of kinetic scale ULF waves that are associated with radiation belt electron dynamics and energetic particle injections.

  18. A cellular automata-based model of Earth's magnetosphere in relation with Dst index

    Science.gov (United States)

    Banerjee, Adrija; Bej, Amaresh; Chatterjee, T. N.

    2015-05-01

    The disturbance storm time (Dst) index, a measure of the strength of a geomagnetic storm, is difficult to predict by some conventional methods due to its abstract structural complexity and stochastic nature though a timely geomagnetic storm warning could save society from huge economic losses and hours of related hazards. Self-organized criticality and the concept of many-body interactive nonlinear system can be considered an explanation for the fundamental mechanism of the nonstationary geomagnetic disturbances controlled by the perturbed interplanetary conditions. The present paper approaches this natural phenomena by a sandpile-like cellular automata-based model of magnetosphere, taking the real-time solar wind and both the direction and magnitude of the BZ component of the real-time interplanetary magnetic field as the system-controlling input parameters. Moreover, three new parameters had been introduced in the model which modify the functional relationships between the variables and regulate the dynamical behavior of the model to closely approximate the actual geomagnetic fluctuations. The statistical similarities between the dynamics of the model and that of the actual Dst index series during the entire 22nd solar cycle signifies the acceptability of the model.

  19. Oblique Whistler-Mode Waves in the Earth's Inner Magnetosphere: Energy Distribution, Origins, and Role in Radiation Belt Dynamics

    Science.gov (United States)

    Artemyev, Anton; Agapitov, Oleksiy; Mourenas, Didier; Krasnoselskikh, Vladimir; Shastun, Vitalii; Mozer, Forrest

    2016-04-01

    In this paper we review recent spacecraft observations of oblique whistler-mode waves in the Earth's inner magnetosphere as well as the various consequences of the presence of such waves for electron scattering and acceleration. In particular, we survey the statistics of occurrences and intensity of oblique chorus waves in the region of the outer radiation belt, comprised between the plasmapause and geostationary orbit, and discuss how their actual distribution may be explained by a combination of linear and non-linear generation, propagation, and damping processes. We further examine how such oblique wave populations can be included into both quasi-linear diffusion models and fully nonlinear models of wave-particle interaction. On this basis, we demonstrate that varying amounts of oblique waves can significantly change the rates of particle scattering, acceleration, and precipitation into the atmosphere during quiet times as well as in the course of a storm. Finally, we discuss possible generation mechanisms for such oblique waves in the radiation belts. We demonstrate that oblique whistler-mode chorus waves can be considered as an important ingredient of the radiation belt system and can play a key role in many aspects of wave-particle resonant interactions.

  20. Intermittency of the turbulent processes in the Earth's magnetosphere detected from the ground-based measurements

    Energy Technology Data Exchange (ETDEWEB)

    Stepanova, Marina [Physical Department, Universidad de Santiago de Chile (Chile); Foppiano, Alberto; Ovalle, Elias [Departmento de Geofisica, Universidad de Conception (Chile); Antonova, Elizavieta [Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow (Russian Federation); Troshichev, Oleg [Department of Geophysics, Arctic and Antarctic Research Institute, St. Petersburg (Russian Federation)], E-mail: mstepano@usach.cl

    2008-11-01

    Turbulent processes in the Earth's magnetosphere are reflected in the dynamical behavior of the geomagnetic indices and other parameters determined from ground based observations. Intermittent properties of one minute Polar Cap (PC) index and auroral radio wave absorption are studied using 1995-2000 data sets. It was found that the probability distribution functions (PDFs) of both PC-index and absorption fluctuations display a strong non-Gaussian shape. This indicates that they are not characterized by a global time self-similarity but rather exhibit intermittency, as previously reported for solar wind velocity and auroral electrojet index values. In the case of the auroral absorption it was also found that intermittency strongly depends on the magnetic local time, being largest in the nighttime sector. This shows that the acceleration of precipitating particles is intermittent, especially near the substorm eye, where the level of turbulence increases. Application of the Local Intermittency Measure (LIM) technique confirms the aforementioned results to a better precision.

  1. EMIC-wave-moderated flux limitations of ring current energetic ion intensities in the multi-species plasmas of Earth's inner magnetosphere

    Science.gov (United States)

    Mauk, B.

    2013-12-01

    One of the early sophisticated integrations of theory and observations of the space age was the development in 1966 of the integral Kennel-Petschek flux limit for trapped energetic electrons and ions within Earth's inner magnetosphere. Specifically, it was proposed that: 1) trapped particle distributions in the magnetic bottle configuration of the inner magnetosphere are intrinsically unstable to the generation various plasma waves and 2) ionospheric reflection of some waves back into the trapped populations leads to runaway growth of the waves and dramatic loss of particles for particle integral intensities that rise above a fairly rigidly specified upper limit. While there has been a long hiatus in utilization of the KP limit in inner magnetospheric research, there have been recent highly successful reconsiderations of more general forms of the KP limit for understanding radiation belt electron intensities and spectral shapes, resulting from improvements in theoretical tools. Such a reconsideration has not happened for energetic trapped ions, perhaps due to the perceived immense complexity of the generation of the Electromagnetic Ion Cyclotron (EMIC) waves, that scatter the energetic ions, for plasmas containing multiple ionic species (H, He, O). Here, a differential Kennel-Petschek (KP) flux limit for magnetospheric energetic ions is devised taking into account multiple ion species effects on the EMIC waves. This new theoretical approach is applied to measured Earth magnetosphere energetic ion spectra (~ keV to ~ 1 MeV) for radial positions (L) 3 to 6.7 RE. The flatness of the most intense spectral shapes for mechanism, but modifications of traditional KP parameters are needed to account for maximum intensities up to 5 times greater than expected. Future work using the Van Allen Probes mission will likely resolve outstanding uncertainties.

  2. Optical evidence for Alfven wave breaking in the near-Earth magnetosphere

    Science.gov (United States)

    Semeter, J.; Blixt, M.

    2006-12-01

    Alfvén waves propagating obliquely to the Earth's magnetic lines of force become dispersive when the perpendicular wavelength approaches the collisionless electron skin depth. The dispersion results in two simultaneous effects: (1) wave energy becomes coupled to particle kinetic energy such that parallel acceleration of electrons is possible, and (2) wave energy spreads azimuthally across the background magnetic field, with phase- and group-velocities oppositely directed. Validation of this mechanism requires two-dimensional, time-dependent measurements of the dispersing wave packet. Such evidence should be available in video measurements of the aurora-borealis. An analysis of high-speed, narrow-field, intensified video of dynamic aurora event is presented, confirming the salient predictions for inertial Alfvén wave dispersion.

  3. Turbulence in a Global Magnetohydrodynamic Simulation of the Earth's Magnetosphere during Northward and Southward Interplanetary Magnetic Field

    Science.gov (United States)

    El-Alaoui, M.; Richard, R. L.; Ashour-Abdalla, M.; Walker, R. J.; Goldstein, M. L.

    2012-01-01

    We report the results of MHD simulations of Earth's magnetosphere for idealized steady solar wind plasma and interplanetary magnetic field (IMF) conditions. The simulations feature purely northward and southward magnetic fields and were designed to study turbulence in the magnetotail plasma sheet. We found that the power spectral densities (PSDs) for both northward and southward IMF had the characteristics of turbulent flow. In both cases, the PSDs showed the three scale ranges expected from theory: the energy-containing scale, the inertial range, and the dissipative range. The results were generally consistent with in-situ observations and theoretical predictions. While the two cases studied, northward and southward IMF, had some similar characteristics, there were significant differences as well. For southward IMF, localized reconnection was the main energy source for the turbulence. For northward IMF, remnant reconnection contributed to driving the turbulence. Boundary waves may also have contributed. In both cases, the PSD slopes had spatial distributions in the dissipative range that reflected the pattern of resistive dissipation. For southward IMF there was a trend toward steeper slopes in the dissipative range with distance down the tail. For northward IMF there was a marked dusk-dawn asymmetry with steeper slopes on the dusk side of the tail. The inertial scale PSDs had a dusk-dawn symmetry during the northward IMF interval with steeper slopes on the dawn side. This asymmetry was not found in the distribution of inertial range slopes for southward IMF. The inertial range PSD slopes were clustered around values close to the theoretical expectation for both northward and southward IMF. In the dissipative range, however, the slopes were broadly distributed and the median values were significantly different, consistent with a different distribution of resistivity.

  4. A novel approach to the dynamical complexity of the Earth's magnetosphere at geomagnetic storm time-scales based on recurrences

    Science.gov (United States)

    Donner, Reik; Balasis, Georgios; Stolbova, Veronika; Wiedermann, Marc; Georgiou, Marina; Kurths, Jürgen

    2016-04-01

    Magnetic storms are the most prominent global manifestations of out-of-equilibrium magnetospheric dynamics. Investigating the dynamical complexity exhibited by geomagnetic observables can provide valuable insights into relevant physical processes as well as temporal scales associated with this phenomenon. In this work, we introduce several innovative data analysis techniques enabling a quantitative analysis of the Dst index non-stationary behavior. Using recurrence quantification analysis (RQA) and recurrence network analysis (RNA), we obtain a variety of complexity measures serving as markers of quiet- and storm-time magnetospheric dynamics. We additionally apply these techniques to the main driver of Dst index variations, the V BSouth coupling function and interplanetary medium parameters Bz and Pdyn in order to discriminate internal processes from the magnetosphere's response directly induced by the external forcing by the solar wind. The derived recurrence-based measures allow us to improve the accuracy with which magnetospheric storms can be classified based on ground-based observations. The new methodology presented here could be of significant interest for the space weather research community working on time series analysis for magnetic storm forecasts.

  5. Magnetospheric Multiscale (MMS) Mission Observations of Energetic Particle Dynamics and Structures Prior To and During Its First Encounters with the Reconnection-Rich Regions of Earth's Magnetopause

    Science.gov (United States)

    Mauk, B.; Westlake, J. H.; Cohen, I. J.; Blake, J. B.; Fennell, J. F.; Baker, D. N.; Jaynes, A. N.; Spence, H. E.; Burch, J. L.; Torbert, R. B.; Moore, T. E.; Giles, B. L.; Pollock, C. J.; Fuselier, S. A.; Nakamura, R.; Reeves, G. D.

    2015-12-01

    The Magnetospheric Multiscale (MMS) mission, launched on 13 March 2015, comprises 4 spacecraft flying in close formation in highly elliptical, near-Earth-equatorial orbits targeting understanding of the fundamental physics of magnetic reconnection using Earth's magnetosphere as a plasma laboratory. The Energetic Particle Detector (EPD) Investigation on MMS is one of several fields-and-particles investigations. EPD comprises two sensor types, the Energetic Ion Spectrometer (EIS) with one instrument on each of the 4 spacecraft, and the Fly's Eye Energetic Particle Spectrometer (FEEPS) with 2 instruments on each of the 4 spacecraft. EIS measures energetic ion energy, angle and elemental compositional distributions for protons from 1 MeV. FEEPS measures instantaneous ( 1/3 s) all sky images of energetic electrons from 25 keV to > 0.6 MeV and also measures total ion energy distributions from 45 keV to > 0.5 MeV to be used in conjunction with EIS to measure all-sky ion distributions. During the preparation stages for the prime mission (prior to 1 September 2015), with a 1.2 x 12 RE orbit precessing across the root of the magnetotail, EPD observed energetic particle responses to depolarization fronts and related particle injection features, ion composition and flow dynamics associated with injections, the dynamic formation of trapping-boundary-like features at intermediate magnetic latitudes, striking electron beam and butterfly distributions likely providing precursors to observations of the magnetopause-magnetosphere interface, and intense modulations in association ULF waves. In this overview presentation, we use some of these observations to document the promise that the EPD investigation holds for contributing to the resolution of reconnection-induced particle acceleration and structuring. We then show the early-mission energetic particle structures and dynamics observed at the magnetopause and in association with reconnection events identified by the mission for

  6. Study of energy transfer from the solar wind to Earth's magnetosphere using the 3D- MHD BATS-R-US global model

    Science.gov (United States)

    Jauer, P. R.; Gonzalez, W. D.; de Souza Costa, C. L.; Souza, V. M.

    2013-12-01

    The interaction, transport and conversion of energy between the solar wind and Earth's magnetosphere have been studied for decades through in situ measurements and Magnetohydrodynamics simulation, (MHD). Nevertheless, due to the vast regions of space and nonlinearities of the physical processes there are many questions that still remain without conclusive answers. Currently, the MHD simulation is a powerful tool that helps other means of already existing research, even within its theoretical limitation; it provides information of the space regions where in situ measurements are rare or nonexistent. The aim of this work is the study of energy transfer from the solar wind through the calculation of the divergence of the Poynting vector for the inner regions of the Earth's magnetosphere, especially the magneto tail using 3D global MHD numerical code Space Weather Modelling Framework (SWMF) / (Block Adaptive Tree Solar wind Roe Upwind Scheme) (BATS-R-US), developed by the University of Michigan. We conducted a simulation study for the event that occurred on September 21-27, 1999, for which the peak value of the interplanetary magnetic field was -22 nT, and gave rise to an intense magnetic storm with peak Dst of -160 nT. Furthermore, we compare the results of the power estimated by the model - through the integration of the Poynting vector in rectangular region of the tail, with a domain -130 powerful tool to reproduce the observations with a good degree of reliability.

  7. Energetic electron fluxes in the earth's outer magnetosphere according to observations from the Prognoz-3 station. [40 to 300 keV

    Energy Technology Data Exchange (ETDEWEB)

    Antonova, A.E.; Nikolaeva, N.S.

    1978-01-01

    The Energetic electron distribution (from 40 to 300 keV) at middle and high latitudes in the outer magnetosphere of the earth, observed at the Prognoz 3 station from February to October 1973, is discussed. Considerable electron fluxes exist above the noon stable trapping boundary in the region near the equatorial flank of the dayside polar cusp. Pronounced enhancement of the 40 keV electron intensity and some in 300 keV electron bursts were detected on the magnetopause, which are agreement with electron layer measurements from the IMP and HEOS satellites and from the Prognoz 1 station. Quasiperiodic modulation of energetic electron fluxes with a period of about 3 to 5 minutes was observed and can be associated with the magnetopause motion and with oscillations of the magnetic field of the earth.

  8. Response of the Earth's Magnetosphere and Ionosphere to Solar Wind Driver and Ionosphere Load: Results of Global MHD Simulations

    Institute of Scientific and Technical Information of China (English)

    XIONG Ming; PENG Zhong; HU You-Qiu; ZHENG Hui-Nan

    2009-01-01

    Three-dimensional global magnetohydrodynamic simulations of the solar wind magnetosphere-ionosphere system are carried out to explore the dependence of the magnetospheric reconnection voltage, the ionospheric transpolar potential, and the field aligned currents (FACs) on the solar wind driver and ionosphere load for the cases with pure southward interplanetary magnetic field (IMP). It is shown that the reconnection voltage and the transpolar potential increase monotonically with decreasing Pedersen conductance (∑p ), increasing southward IMF strength (Bs) and solar wind speed (vsw). Moreover, both regions 1 and 2 FACs increase when Bs and vsw increase, whereas the two currents behave differently in response to ∑p. As ∑p increases, the region 1 FAC increases monotonically, but region 2 FAC shows a non-monotonic response to the increase of ∑p : it first increases in the range of (0,5) Siemens and then decreases for ∑p 5 Siemens.

  9. The Sun, Its Extended Corona, the Interplanetary Space, the Earth's Magnetosphere, Ionosphere, Middle and Low Atmosphere, are All Parts of a Complex System - the Heliosphere

    Science.gov (United States)

    Gopalswamy, Natchimuthuk

    2011-01-01

    Various manifestations of solar activity cause disturbances known as space weather effects in the interplanetary space, near-Earth environment, and all the Earth's "spheres. Longterm variations in the frequency, intensity and relative importance of the manifestations of solar activity are due to the slow changes in the output of the solar dynamo, and they define space climate. Space climate governs long-term variations in geomagnetic activity and is the primary natural driver of terrestrial climate. To understand how the variable solar activity affects the Earth's environment, geomagnetic activity and climate on both short and long time scales, we need to understand the origins of solar activity itself and its different manifestations, as well as the sequence of coupling processes linking various parts of the system. This session provides a forum to discuss the chain of processes and relations from the Sun to the Earth's surface: the origin and long-term and short-term evolution of solar activity, initiation and temporal variations in solar flares, CMEs, coronal holes, the solar wind and its interaction with the terrestrial magnetosphere, the ionosphere and its connection to the neutral dominated regions below and the plasma dominated regions above, the stratosphere, its variations due to the changing solar activity and its interactions with the underlying troposphere, and the mechanisms of solar influences on the lower atmosphere on different time-scales. Particularly welcome are papers highlighting the coupling processes between the different domains in this complex system.

  10. Chapman Conference: Magnetospheric Substorms

    Science.gov (United States)

    Iijima, Takesi; Kokubun, Susumu; Kan, Joseph R.; Potemra, T. A.

    Magnetospheric substorms are characterized by fascinating auroral displays in the ionosphere and by complex plasma dynamics in the magnetotail. The complicated plasma processes associated with substorms fascinated space researchers even before the space age, when observations were limited to the Earth's surface. These processes are believed to be fundamentally important to plasma physics, and also to apply to solar flares and other cosmic phenomena. Substorms have been the focus of intense study and controversy within space science for several decades.

  11. Plasma Turbulence in Earth's Magnetosheath Observed by the Magnetospheric Multiscale Mission over the First Sub-Solar Apogee Pass

    Science.gov (United States)

    Mackler, D. A.; Avanov, L. A.; Boardsen, S. A.; Giles, B. L.; Pollock, C.; Smith, S. E.; Uritsky, V. M.

    2016-12-01

    Magnetic reconnection, a process in which the magnetic topology undergoes multi-scale changes, is a significant mechanism for particle energization as well as energy dissipation. Reconnection is observed to occur in thin current sheets generated between two regions of magnetized plasma merging with a non-zero shear angle. Within a thinning current sheet, the dominant scale size approaches first the ion and then electron kinetic scale. The plasma becomes demagnetized, field lines transform, then once again the plasma becomes frozen-in. The reconnection process accelerates particles, leading to heated jets of plasma. Turbulence is another fundamental process in collisionless plasmas. Despite decades of turbulence studies, an essential science question remains as to how turbulent energy dissipates at small scales by heating and accelerating particles. Turbulence in both plasmas and fluids has a fundamental property in that it follows an energy cascade into smaller scales. Energy introduced into a fluid or plasma can cause large scale motion, introducing vorticity, which merge and interact to make increasingly smaller eddies. It has been hypothesized that turbulent energy in magnetized plasmas may be dissipated by magnetic reconnection, just as viscosity dissipates energy in neutral fluid turbulence. The focus of this study is to use the new high temporal resolution suite of instruments on board the Magnetospheric MultiScale (MMS) mission to explore this hypothesis. An observable feature of the energy cascade in a turbulent magnetized plasma is its similarity to classical hydrodynamics in that the Power Spectral Density (PSD) of turbulent fluctuations follows a Kolmogorov-like power law (f -5/3). We use highly accurate (0.1 nT) Flux Gate Magnetometer (FGM) data to derive the PSD as a function of frequency in the magnetic fluctuations. Given that we are able to confirm the turbulent nature of the flow field; we apply the method of Partial Variance of Increments (PVI) to

  12. Origin, transport, and losses of energetic He(+) and He(2+) ions in the magnetosphere of the Earth - AMPTE/CCE observations

    Science.gov (United States)

    Kremser, G.; Wilken, B.; Gloeckler, G.; Hamilton, D. C.; Ipavich, F. M.; Kistler, L. M.; Tanskanen, P.

    1993-01-01

    Data from the ion charge-energy-mass spectrometer CHEM flown on AMPTE/CCE spacecraft are used to investigate the origin, transport, and losses of energetic He(+) and He(2+) ions in the earth's magnetosphere. The L profiles of the average ion phase space density f were determined as a function of the magnetic momentum. It is shown that the L profiles have an inner part, where f increases with L for both He(+) adn He(2+) and where steady-state conditions are fulfilled. The outer boundary L(lim) of this region is located at a distance that depends on the ion species and the geomagnetic activity level. Steady-state conditions continue outside L(lim) for He(+) ions, while the He(2+) ion distribution outside L(lim) is strongly influenced by ion convection causing a lack of steady-state conditions. It is concluded that solar wind is the origin of the He(2+), while a mixed origin is suggested for the He(+) ions, in which the major contribution is from the solar wind via charge exchange production from the He(2+) ions.

  13. Cosmic Rays trajectory reconstruction in the Earth Magnetosphere: External Field models importance during the last solar active period (from 2011 to 2013)

    Science.gov (United States)

    Grandi, Davide; Della Torre, Stefano; Pensotti, Simonetta; Bobik, Pavol; Kudela, Karel; Rancoita, Pier Giorgio; Gervasi, Massimo; Jeroen Boschini, Matteo; Rozza, Davide; La vacca, Giuseppe; Tacconi, Mauro

    Geomagsphere is a backtracing code for Cosmic Rays trajectory reconstruction in the Earth Magnetosphere that has been developed with last models of Internal (IGRF-11) and External (Tsyganenko 1996 and 2005) field components. This backtracing technique was used to separate Primary Cosmic Rays Particles, in case of allowed trajectory, from Secondary particles, in case of forbidden trajectory. We compared Magnetic Field measurements with and without the external field model with satellite data in past periods, in particular GOES (1998) and CLUSTER (2004) data. For both periods TS05 reproduces the magnetc field components with good accuracy. The specificity of the TS05 model, designed for solar storms, was tested comparing it with data taken by CLUSTER during the last solar active period (from 2011 to 2013) During Solar Flares (occurred march and May 2012), the usage of such an external field has a relevavant impact on fraction of AMS-02 cosmic rays identified as trapped and secondary particles, especially in high geomagnetic latitudes, as was expecte by some previous simulations, in comparison with the Internal Field only.

  14. Istoriya issledovanij kosmicheskogo prostranstva. Chast' II. Estestvennaya i iskusstvennaya radiatsiya v magnitosfere Zemli %t History of space researches. Part 2. Natural and artificial radiation in the Earth magnetosphere

    Science.gov (United States)

    Temnyj, V. V.

    The discussion about the structure and source of the intense radiation zone detected onboard the first satellites begun in 1958 and was finished in 1961. It was found that this zone is not a unitary reservoir of auroral electrons. Its remote part called the "outer radiation belt" indeed if filled with electrons, but their energies far exceed the auroral energy range. The near-Earth area of the radiation zone consisting of protons with energies Ep ~ 100 MeV was called the "inner radiation belt". Intense energy fluxes of electrons were also detected in this zone. Particles of the radiation belts are trapped in the geomagnetic field. They rotate around and bounce along the field lines and also drift around of the Earth. The drift existence was proved by the formation of narrow artificial radiation belts over the whole globe after high-altitude by the "ARGUS" nuclear explosions on September 1958. They were used as markers for creation of two-dimensional geomagnetic coordinate system (L,B) applied to define the distributions of trapped particles. Until 1960, the electron fluxes of the outer radiation belt were assumed to be a possible source of auroras. However, the subsequent experiments have lowered the level of these fluxes by orders of magnitude, and these data argued against this assumption. The geomagnetic field depressions detected in 1959 were referred to an effect of the ring current, which began to be registered in 1961-1964 as fluxes of trapped protons with energies Ep ~ 100 keV. Their energy density was not less than 10% of the magnetic-energy local density B2/8π, and constant diamagnetic field depression by its was not less than 15%. The "STARFISH" high-altitude thermonuclear explosion on July 9, 1962 unexpectedly has resulted in the formation of an artificial radiation belt filled with electrons. It has polluted the Earth's central magnetosphere for many years. Nevertheless, the experiment made it possible to obtain the distribution of electrons of a

  15. Dynamic Theory of Relativistic Electrons Stochastic Heating by Whistler Mode Waves with Application to the Earth Magnetosphere

    Science.gov (United States)

    Khazanov, G. V.; Tel'nikhin, A. A.; Kronberg, T. K.

    2007-01-01

    In the Hamiltonian approach an electron motion in a coherent packet of the whistler mode waves propagating along the direction of an ambient magnetic field is studied. The physical processes by which these particles are accelerated to high energy are established. Equations governing a particle motion were transformed in to a closed pair of nonlinear difference equations. The solutions of these equations have shown there exists the energetic threshold below that the electron motion is regular, and when the initial energy is above the threshold an electron moves stochastically. Particle energy spectra and pitch angle electron scattering are described by the Fokker-Planck-Kolmogorov equations. Calculating the stochastic diffusion of electrons due to a spectrum of whistler modes is presented. The parametric dependence of the diffusion coefficients on the plasma particle density, magnitude of wave field, and the strength of magnetic field is studies. It is shown that significant pitch angle diffusion occurs for the Earth radiation belt electrons with energies from a few keV up to a few MeV.

  16. Large-scale variation of electron parameters from Quasi-Thermal Noise during WIND perigees in the Earth's magnetosphere

    Science.gov (United States)

    Issautier, Karine; Ongala-Edoumou, Samuel; Moncuquet, Michel

    2016-04-01

    The quasi-thermal noise (QTN) method consists in measuring the electrostatic fluctuations produced by the thermal motion of the ambient particles. This noise is detected with a sensitive wave receiver and measured at the terminal of a passive electric antenna, which is immersed in a stable plasma. The analysis of the so-called QTN provides in situ measurements, mainly the total electron density, with a good accuracy, and thermal temperature in a large number of space media. We create a preliminary electron database to analyse the anti-correlation between electron density and temperature deduced from WIND perigees in the Earth's plasmasphere. We analyse the radio power spectra measured by the Thermal Noise Receiver (TNR), using the 100-m long dipole antenna, onboard WIND spacecraft. We develop a systematic routine to determine the electron density, core and halo temperature and the magnitude of the magnetic field based on QTN in Bernstein modes. Indeed, the spectra are weakly banded between gyroharmonics below the upper hybrid frequency, from which we derive the local electron density. From the gyrofrequency determination, we obtain an independent measure of the magnetic field magnitude, which is in close agreement with the onboard magnetometer.

  17. Jupiter's magnetosphere and radiation belts

    Science.gov (United States)

    Kennel, C. F.; Coroniti, F. V.

    1979-01-01

    Radioastronomy and Pioneer data reveal the Jovian magnetosphere as a rotating magnetized source of relativistic particles and radio emission, comparable to astrophysical cosmic ray and radio sources, such as pulsars. According to Pioneer data, the magnetic field in the outer magnetosphere is radially extended into a highly time variable disk-shaped configuration which differs fundamentally from the earth's magnetosphere. The outer disk region, and the energetic particles confined in it, are modulated by Jupiter's 10 hr rotation period. The entire outer magnetosphere appears to change drastically on time scales of a few days to a week. In addition to its known modulation of the Jovian decametric radio bursts, Io was found to absorb some radiation belt particles and to accelerate others, and most importantly, to be a source of neutral atoms, and by inference, a heavy ion plasma which may significantly affect the hydrodynamic flow in the magnetosphere. Another important Pioneer finding is that the Jovian outer magnetosphere generates, or permits to escape, fluxes of relativistic electrons of such intensities that Jupiter may be regarded as the dominant source of 1 to 30 MeV cosmic ray electrons in the heliosphere.

  18. An MHD simulation of the effects of the interplanetary magnetic field By component on the interaction of the solar wind with the earth's magnetosphere during southward interplanetary magnetic field

    Science.gov (United States)

    Ogino, T.; Walker, R. J.; Ashour-Abdalla, M.; Dawson, J. M.

    1986-01-01

    The interaction between the solar wind and the earth's magnetosphere has been studied by using a time-dependent three-dimensional MHD model in which the IMF pointed in several directions between dawnward and southward. When the IMF is dawnward, the dayside cusp and the tail lobes shift toward the morningside in the northern magnetosphere. The plasma sheet rotates toward the north on the dawnside of the tail and toward the south on the duskside. For an increasing southward IMF component, the plasma sheet becomes thinner and subsequently wavy because of patchy or localized tail reconnection. At the same time, the tail field-aligned currents have a filamentary layered structure. When projected onto the northern polar cap, the filamentary field-aligned currents are located in the same area as the region 1 currents, with a pattern similar to that associated with auroral surges. Magnetic reconnection also occurs on the dayside magnetopause for southward IMF.

  19. Outer Magnetospheric Boundaries Cluster Results

    CERN Document Server

    Paschmann, Goetz; Schwartz, S J

    2006-01-01

    When the stream of plasma emitted from the Sun (the solar wind) encounters Earth's magnetic field, it slows down and flows around it, leaving behind a cavity, the magnetosphere. The magnetopause is the surface that separates the solar wind on the outside from the Earth's magnetic field on the inside. Because the solar wind moves at supersonic speed, a bow shock must form ahead of the magnetopause that acts to slow the solar wind to subsonic speeds. Magnetopause, bow shock and their environs are rich in exciting processes in collisionless plasmas, such as shock formation, magnetic reconnection, particle acceleration and wave-particle interactions. They are interesting in their own right, as part of Earth's environment, but also because they are prototypes of similar structures and phenomena that are ubiquitous in the universe, having the unique advantage that they are accessible to in situ measurements. The boundaries of the magnetosphere have been the target of direct in-situ measurements since the beginning ...

  20. Overview of Solar Wind-Magnetosphere-Ionosphere-Atmosphere Coupling and the Generation of Magnetospheric Currents

    Science.gov (United States)

    Milan, S. E.; Clausen, L. B. N.; Coxon, J. C.; Carter, J. A.; Walach, M.-T.; Laundal, K.; Østgaard, N.; Tenfjord, P.; Reistad, J.; Snekvik, K.; Korth, H.; Anderson, B. J.

    2017-02-01

    We review the morphology and dynamics of the electrical current systems of the terrestrial magnetosphere and ionosphere. Observations from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) over the three years 2010 to 2012 are employed to illustrate the variability of the field-aligned currents that couple the magnetosphere and ionosphere, on timescales from minutes to years, in response to the impact of solar wind disturbances on the magnetosphere and changes in the level of solar illumination of the polar ionospheres. The variability is discussed within the context of the occurrence of magnetic reconnection between the solar wind and terrestrial magnetic fields at the magnetopause, the transport of magnetic flux within the magnetosphere, and the onset of magnetic reconnection in the magnetotail. The conditions under which the currents are expected to be weak, and hence minimally contaminate measurements of the internally-produced magnetic field of the Earth, are briefly outlined.

  1. Advances in Global Magnetosphere Modeling at the Community Coordinated Modeling Center.

    Science.gov (United States)

    Kuznetsova, Maria

    2016-07-01

    The Community Coordinated Modeling Center (CCMC) hosts a set of state-of-the-art global magnetosphere models that are capable to reproduce a broad range of physical phenomena in Earth's magnetosphere. We will discuss successes and challenges in global magnetosphere modeling and the role of non-MHD effects on global dynamics.

  2. The Coughing Pulsar Magnetosphere

    CERN Document Server

    Contopoulos, I

    2005-01-01

    Polar magnetospheric gaps consume a fraction of the electric potential that develops accross open field lines. This effect modifies significantly the structure of the axisymmetric pulsar magnetosphere. We present numerical stead-state solutions for various values of the gap potential. We show that a charge starved magnetosphere contains significantly less electric current than one with freely available electric charges. As a result, electromagnetic neutron star braking becomes inefficient. We argue that the magnetosphere may spontaneously rearrange itself to a lower energy configuration through a dramatic release of electromagnetic field energy and magentic flux. Our results might be relevant in understanding the recent December 27, 2004 burst observed in SGR 1806-20.

  3. Magnetosonic resonances in the magnetospheric plasma

    Science.gov (United States)

    Leonovich, A. S.; Kozlov, D. A.

    2013-05-01

    A problem of coupling between fast and slow magnetosonic waves in Earth's magnetosphere (magnetosonic resonance) is examined. Propagation both slow magnetosonic wave and Alfven wave can easily be canalized along the magnetic field line direction. The main difference between the two is that slow magnetosonic waves dissipate strongly due to their interaction with the background plasma ions, whose temperature is above the electron temperature. In Earth's magnetosphere, however, there is a region where the dissipation of slow magnetosonic waves can be weak—the inner plasmasphere. The slow magnetosonic waves generated there can be registered directly. In other regions, with strong dissipation of slow magnetosonic waves, their signature may be detected through their impact on the Alfven resonance at frequencies for which the resonant Alfven and slow magnetosonic waves exist simultaneously in the magnetosphere. Owing to their strong coupling with the background plasma ions, resonant slow magnetosonic waves can transfer the energy and impulse from the solar wind to the magnetospheric plasma ions via fast magnetosonic waves penetrating into the tail lobes. A problem of resonant conversion of fast magnetosonic waves into slow magnetosonic oscillations in a magnetosphere with dipole-like magnetic field is also examined.

  4. Validation of Magnetospheric Magnetohydrodynamic Models

    Science.gov (United States)

    Curtis, Brian

    Magnetospheric magnetohydrodynamic (MHD) models are commonly used for both prediction and modeling of Earth's magnetosphere. To date, very little validation has been performed to determine their limits, uncertainties, and differences. In this work, we performed a comprehensive analysis using several commonly used validation techniques in the atmospheric sciences to MHD-based models of Earth's magnetosphere for the first time. The validation techniques of parameter variability/sensitivity analysis and comparison to other models were used on the OpenGGCM, BATS-R-US, and SWMF magnetospheric MHD models to answer several questions about how these models compare. The questions include: (1) the difference between the model's predictions prior to and following to a reversal of Bz in the upstream interplanetary field (IMF) from positive to negative, (2) the influence of the preconditioning duration, and (3) the differences between models under extreme solar wind conditions. A differencing visualization tool was developed and used to address these three questions. We find: (1) For a reversal in IMF Bz from positive to negative, the OpenGGCM magnetopause is closest to Earth as it has the weakest magnetic pressure near-Earth. The differences in magnetopause positions between BATS-R-US and SWMF are explained by the influence of the ring current, which is included in SWMF. Densities are highest for SWMF and lowest for OpenGGCM. The OpenGGCM tail currents differ significantly from BATS-R-US and SWMF; (2) A longer preconditioning time allowed the magnetosphere to relax more, giving different positions for the magnetopause with all three models before the IMF Bz reversal. There were differences greater than 100% for all three models before the IMF Bz reversal. The differences in the current sheet region for the OpenGGCM were small after the IMF Bz reversal. The BATS-R-US and SWMF differences decreased after the IMF Bz reversal to near zero; (3) For extreme conditions in the solar

  5. Evidence for particle acceleration during magnetospheric substorms

    Science.gov (United States)

    Lopez, Ramon E.; Baker, Daniel N.

    1994-01-01

    Magnetospheric substorms represent the episodic dissipation of energy stored in the geomagnetic tail that was previously extracted from the solar wind. This energy release produces activity throughout the entire magnetosphere-ionosphere system, and it results in a wide variety of phenomena such as auroral intensifications and the generation of new current systems. All of these phenomena involve the acceleration of particles, sometimes up to several MeV. We present a brief overview of substorm phenomenology. We then review some of the evidence for particle acceleration in Earth's magnetosphere during substorms. Such in-situ observations in this most accessible of all cosmic plasma domains may hold important clues to understanding acceleration processes in more distant astrophysical systems.

  6. Magnetic reconnection during magnetospheric substorms

    Science.gov (United States)

    Baker, Daniel N.

    1996-01-01

    The near earth reconnection model of substorms represents an attempt to place a broad range of observations into a consistent framework. The roles and requirements of reconnection are discussed. High speed plasma sheet flows, thin current sheet instability, substorm triggering, plasmoids and flux ropes in the distant tail, and magnetohydrodynamic simulations are discussed. Substorms are global, coherent sequences of processes involving solar wind/magnetosphere/ionosphere interaction. Magnetic reconnection is required to explain different dayside and polar cap phenomena, which required nightside reconnection. The modification and expansion of the standard near earth neutral line (NENL) model can integrate breakup arcs, current disruption, current wedge features, and localized plasma flows into the magnetic reconnection framework.

  7. Numerical considerations in simulating the global magnetosphere

    Directory of Open Access Journals (Sweden)

    A. J. Ridley

    2010-08-01

    Full Text Available Magnetohydrodynamic (MHD models of the global magnetosphere are very good research tools for investigating the topology and dynamics of the near-Earth space environment. While these models have obvious limitations in regions that are not well described by the MHD equations, they can typically be used (or are used to investigate the majority of magnetosphere. Often, a secondary consideration is overlooked by researchers when utilizing global models – the effects of solving the MHD equations on a grid, instead of analytically. Any discretization unavoidably introduces numerical artifacts that affect the solution to various degrees. This paper investigates some of the consequences of the numerical schemes and grids that are used to solve the MHD equations in the global magnetosphere. Specifically, the University of Michigan's MHD code is used to investigate the role of grid resolution, numerical schemes, limiters, inner magnetospheric density boundary conditions, and the artificial lowering of the speed of light on the strength of the ionospheric cross polar cap potential and the build up of the ring current in the inner magnetosphere. It is concluded that even with a very good solver and the highest affordable grid resolution, the inner magnetosphere is not grid converged. Artificially reducing the speed of light reduces the numerical diffusion that helps to achieve better agreement with data. It is further concluded that many numerical effects work nonlinearly to complicate the interpretation of the physics within the magnetosphere, and so simulation results should be scrutinized very carefully before a physical interpretation of the results is made. Our conclusions are not limited to the Michigan MHD code, but apply to all MHD models due to the limitations of computational resources.

  8. MESSENGER: Exploring Mercury's Magnetosphere

    Science.gov (United States)

    Slavin, James A.

    2008-01-01

    The MESSENGER mission to Mercury offers our first opportunity to explore this planet's miniature magnetosphere since Mariner 10's brief fly-bys in 1974-5. Mercury's magnetosphere is unique in many respects. The magnetosphere of Mercury is the smallest in the solar system with its magnetic field typically standing off the solar wind only - 1000 to 2000 km above the surface. For this reason there are no closed dri-fi paths for energetic particles and, hence, no radiation belts; the characteristic time scales for wave propagation and convective transport are short possibly coupling kinetic and fluid modes; magnetic reconnection at the dayside magnetopause may erode the subsolar magnetosphere allowing solar wind ions to directly impact the dayside regolith; inductive currents in Mercury's interior should act to modify the solar In addition, Mercury's magnetosphere is the only one with its defining magnetic flux tubes rooted in a planetary regolith as opposed to an atmosphere with a conductive ionosphere. This lack of an ionosphere is thought to be the underlying reason for the brevity of the very intense, but short lived, approx. 1-2 min, substorm-like energetic particle events observed by Mariner 10 in Mercury's magnetic tail. In this seminar, we review what we think we know about Mercury's magnetosphere and describe the MESSENGER science team's strategy for obtaining answers to the outstanding science questions surrounding the interaction of the solar wind with Mercury and its small, but dynamic magnetosphere.

  9. Quantitative magnetospheric models: results and perspectives.

    Science.gov (United States)

    Kuznetsova, M.; Hesse, M.; Gombosi, T.; Csem Team

    Global magnetospheric models are indispensable tool that allow multi-point measurements to be put into global context Significant progress is achieved in global MHD modeling of magnetosphere structure and dynamics Medium resolution simulations confirm general topological pictures suggested by Dungey State of the art global models with adaptive grids allow performing simulations with highly resolved magnetopause and magnetotail current sheet Advanced high-resolution models are capable to reproduced transient phenomena such as FTEs associated with formation of flux ropes or plasma bubbles embedded into magnetopause and demonstrate generation of vortices at magnetospheric flanks On the other hand there is still controversy about the global state of the magnetosphere predicted by MHD models to the point of questioning the length of the magnetotail and the location of the reconnection sites within it For example for steady southwards IMF driving condition resistive MHD simulations produce steady configuration with almost stationary near-earth neutral line While there are plenty of observational evidences of periodic loading unloading cycle during long periods of southward IMF Successes and challenges in global modeling of magnetispheric dynamics will be addessed One of the major challenges is to quantify the interaction between large-scale global magnetospheric dynamics and microphysical processes in diffusion regions near reconnection sites Possible solutions to controversies will be discussed

  10. The Interplanetary Magnetic Field and Solar Wind Driven Magnetospheric Reconfiguration

    CERN Document Server

    Savov, E

    2002-01-01

    The magnetic disturbances are associated with electric currents as it is well checked at laboratory room scales and described by the Maxwell's equations of electromagnetic field. The analysis of spacecraft observations for more than a quarter of a century failed to provide a self-consistent three-dimensional picture of the solar wind-magnetosphere dynamo generated magnetospheric and ionospheric current systems. The proposed solar wind and the interplanetary magnetic field (IMF) driven reconfiguration of the earth's magnetosphere directly accounts for the observed magnetic disturbances. So role of the magnetospheric currents in creation of the magnetic disturbances is reconsidered in accordance with some poorly understood observations. A quantitative agreement with observations is demonstrated and a laboratory experiment to test the suggested model of the solar wind/IMF-magnetosphere interaction is described.

  11. Representation of planetary magnetospheric environment with the paraboloid model

    Science.gov (United States)

    Kalegaev, V. V.; Alexeev, I. I.; Belenkaya, E. S.; Mukhametdinova, L. R.; Khodachenko, M. L.; Génot, V.; Kallio, E. J.; Al-Ubaidi, T.; Modolo, R.

    2013-09-01

    Paraboloid model of the Earth's magnetosphere has been developed at Moscow State University to represent correctly the electrodynamics processes in the near-Earth's space [1]. This model is intended to calculate the magnetic field generated by a variety of current systems located on the boundaries and within the boundaries of the Earth's magnetosphere under a wide range of environmental conditions, quiet and disturbed, affected by Solar-Terrestrial interactions simulated by Solar activity such as Solar Flares and related phenomena which induce terrestrial magnetic disturbances such as Magnetic Storms. The model depends on a small set of physical input parameters, which characterize the intensity of large-scale magnetospheric current systems and their location. Among these parameters are a geomagnetic dipole tilt angle, distance to the subsolar point of the magnetosphere, etc. The input parameters depend on real- or quasi-real- time Empirical Data that include solar wind and IMF data as well as geomagnetic indices. A generalized paraboloid model was implemented to represent the magnetospheres of some magnetized planets, e.g. Saturn [2], Jupiter [3], Mercury [4]. Interactive models of the Earth's, Kronian and Mercury's magnetospheres, which take into account specific features of the modeled objects have been realized at Space Monitoring Data Center of SINP MSU [5]. The real-time model of the Earth's magnetosphere is currently working at SINP MSU Space Weather Web-site [6]. Data from different sources (satellite measurements, simulation data bases and online services) are accumulated inside a digital framework developed within the FP7 project IMPEx. Paraboloid model of the magnetospheres (PMM) is part of this infrastructure. A set of Webservices to provide the access to PMM calculations and to enable the modeling data post-processing under SOAP protocol have been created. These will be implemented for easy data exchange within IMPEx infrastructure.

  12. Magnetospheric lion roars

    Directory of Open Access Journals (Sweden)

    W. Baumjohann

    Full Text Available The Equator-S magnetometer is very sensitive and has a sampling rate normally of 128 Hz. The high sampling rate for the first time allows detection of ELF waves between the ion cyclotron and the lower hybrid frequencies in the equatorial dawnside magnetosphere. The characteristics of these waves are virtually identical to the lion roars typically seen at the bottom of the magnetic troughs of magnetosheath mirror waves. The magnetospheric lion roars are near-monochromatic packets of electron whistler waves lasting for a few wave cycles only, typically 0.2 s. They are right-hand circularly polarized waves with typical amplitudes of 0.5 nT at around one tenth of the electron gyrofrequency. The cone angle between wave vector and ambient field is nearly always smaller than 1°.

    Key words: Magnetospheric physics (magnetospheric configuration and dynamics; MHD waves and instabilities; plasma waves and instabilities

  13. Mercury's Dynamic Magnetosphere: What Have We Learned from MESSENGER?

    Science.gov (United States)

    Slavin, James A.

    2016-04-01

    Mercury's magnetosphere is created by the solar wind interaction with its dipolar, spin-axis aligned, northward offset intrinsic magnetic field. Structurally it resembles that of the Earth in many respects, but the magnetic field intensities and plasma densities are all higher at Mercury due to conditions in the inner solar system. Magnetospheric plasma at Mercury appears to be primarily of solar wind origin, i.e. H+ and He++, but with 10% Na+ derived from the exosphere. Solar wind sputtering and other processes promote neutrals from the regolith into the exosphere where they may be ionized and incorporated into the magnetospheric plasma population. At this point in time, about one year after MESSENGER's impact and one year prior to BepiColombo's launch, we review MESSENGER's observations of magnetospheric dynamics and structure. In doing so we will provide our best answers to the following six questions: Question #1: How do magnetosheath conditions at Mercury differ from what is found at the other planets? Question #2: How do conditions in Mercury's magnetosheath contribute to the dynamic nature of Mercury's magnetosphere? How does magnetopause reconnection at Mercury differ from what is seen at Earth? Are flux transfer events (FTEs) a major driver of magnetospheric convection at Mercury? Question #3: Does reconnection ever erode the dayside magnetosphere to the point where the subsolar region of the surface is exposed to direct solar wind impact? To what extent do induction currents driven in Mercury's interior limit the solar wind flux to the surface? Do FTEs contribute significantly to the solar wind flux reaching the surface? Question #4: What effects do heavy planetary ions have on Mercury's magnetosphere? Question #5: Does Mercury's magnetotail store and dissipate magnetic energy in a manner analogous to substorms at Earth? How is the process affected by the lack of an ionosphere and the expected high electrical resistivity of the crust? Question #6: How

  14. Magnetosphere Environment from Solar System Planets/Moons to Exoplanets

    Science.gov (United States)

    Alexeev, Igor I.; Grygoryan, Maria S.; Belenkaya, Elena S.; Kalegaev, Vladimir V.; Khodachenko, Maxim

    First we discuss the solar wind plasma interaction with the Solar System planets that have intrinsic magnetic fields: Mercury, Earth, Jupiter, and Saturn are discussed. As a result of such an interaction cavities, which are free from the solar wind plasma and occupied by the planetary magnetic field are created. These cavities are usually called magnetospheres are surrounded and bound by the magnetopause. The magnetopause preserved the planetary magnetic field penetration into the magnetosheath so that its impossible for the magnetosheath plasma flow to penetrate into the magnetosphere. The magnetosheath are placed between the bow shock and the magnetopause. The bow shock forms a boundary against the unshocked super Alvénic plasma flow. As demonstrated by the analysis of the Mercury, Earth, Jupiter, and Saturn magnetopauses, these surfaces can be well described by a paraboloid of revolution with different subsolar distances and flaring angles. Based on this fact an universal model of the planetary magnetosphere can be constructed. We chose the planets in the inner magnetospheres of which the magnetic field vectors have been measured by orbiting spacecraft magnetometers. The proposed models describe the basic physical processes that are responsible for the structure and dynamics of the planetary magnetospheres. Additionally to the inner planetary field the different magnetospheric sources of magnetic field are included in the model. Finally, we discuss how these magnetosphere models can be applied to exoplanets in a comparative way.

  15. The Nonlinear Magnetosphere: Expressions in MHD and in Kinetic Models

    Science.gov (United States)

    Hesse, Michael; Birn, Joachim

    2011-01-01

    Like most plasma systems, the magnetosphere of the Earth is governed by nonlinear dynamic evolution equations. The impact of nonlinearities ranges from large scales, where overall dynamics features are exhibiting nonlinear behavior, to small scale, kinetic, processes, where nonlinear behavior governs, among others, energy conversion and dissipation. In this talk we present a select set of examples of such behavior, with a specific emphasis on how nonlinear effects manifest themselves in MHD and in kinetic models of magnetospheric plasma dynamics.

  16. Earth

    CERN Document Server

    Carter, Jason

    2017-01-01

    This curriculum-based, easy-to-follow book teaches young readers about Earth as one of the eight planets in our solar system in astronomical terms. With accessible text, it provides the fundamental information any student needs to begin their studies in astronomy, such as how Earth spins and revolves around the Sun, why it's uniquely suitable for life, its physical features, atmosphere, biosphere, moon, its past, future, and more. To enhance the learning experience, many of the images come directly from NASA. This straightforward title offers the fundamental information any student needs to sp

  17. Global Effects of the Interplanetary Shock Propagation through the Earth's Inner Magnetosphere: 3D Hybrid Kinetic ModelingA.S. Lipatov {1}, D.G. Sibeck {2}{1} GPHI UMBC/NASA GSFC, Greenbelt, MD 20771, USA {2} NASA GSFC, Greenbelt, MD 20771, USA

    Science.gov (United States)

    Lipatov, A. S.; Sibeck, D. G.

    2015-12-01

    We use a new hybrid kinetic model to simulate the response of ring current, outer radiation belt, and plasmasphere particle populations to impulsive interplanetary shocks. Since particle distributions attending the interplanetary shock waves and in the ring current and radiation belts are non-Maxwellian, wave-particle interactions play a crucial role in energy transport within the inner magnetosphere. Finite gyroradius effects become important in mass loading the shock waves with the background plasma in the presence of higher energy ring current and radiation belt ions and electrons. Initial results show that the shock causes strong deformations in the global structure of the ring current, radiation belt, and plasmasphere. The ion velocity distribution functions at the shock front, in the ring current, and in the radiation belt help us to determine energy transport through the Earth's inner magnetosphere. We compare our predictions with THEMIS and Van Allen Probes spacecraft observations.

  18. 3-D force-balanced magnetospheric configurations

    Directory of Open Access Journals (Sweden)

    S. Zaharia

    2004-01-01

    Full Text Available The knowledge of plasma pressure is essential for many physics applications in the magnetosphere, such as computing magnetospheric currents and deriving mag-netosphere-ionosphere coupling. A thorough knowledge of the 3-D pressure distribution has, however, eluded the community, as most in situ pressure observations are either in the ionosphere or the equatorial region of the magnetosphere. With the assumption of pressure isotropy there have been attempts to obtain the pressure at different locations,by either (a mapping observed data (e.g. in the ionosphere along the field lines of an empirical magnetospheric field model, or (b computing a pressure profile in the equatorial plane (in 2-D or along the Sun-Earth axis (in 1-D that is in force balance with the magnetic stresses of an empirical model. However, the pressure distributions obtained through these methods are not in force balance with the empirical magnetic field at all locations. In order to find a global 3-D plasma pressure distribution in force balance with the magnetospheric magnetic field, we have developed the MAG-3-D code that solves the 3-D force balance equation ${vec J} times {vec B} = nabla P$ computationally. Our calculation is performed in a flux coordinate system in which the magnetic field is expressed in terms of Euler potentials as ${vec B} = nabla psi times nabla alpha$. The pressure distribution, $P = P(psi, alpha$, is prescribed in the equatorial plane and is based on satellite measurements. In addition, computational boundary conditions for ψ surfaces are imposed using empirical field models

  19. Onset of magnetospheric substorms.

    Science.gov (United States)

    Tsurutani, B.; Bogott, F.

    1972-01-01

    An examination of the onset of magnetospheric substorms is made by using ATS 5 energetic particles, conjugate balloon X rays and electric fields, all-sky camera photographs, and auroral-zone magnetograms. It is shown that plasma injection to ATS distances, conjugate 1- to 10-keV auroral particle precipitation, energetic electron precipitation, and enhancements of westward magnetospheric electric-field component all occur with the star of slowly developing negative magnetic bays. No trapped or precipitating energetic-particle features are seen at ATS 5 when later sharp negative magnetic-bay onsets occur at Churchill or Great Whale River.

  20. Magnetospheric Multiscale Overview and Science Objectives

    Science.gov (United States)

    Burch, J. L.; Moore, T. E.; Torbert, R. B.; Giles, B. L.

    2015-01-01

    Magnetospheric Multiscale (MMS), a NASA four-spacecraft constellation mission launched on March 12, 2015, will investigate magnetic reconnection in the boundary regions of the Earth's magnetosphere, particularly along its dayside boundary with the solar wind and the neutral sheet in the magnetic tail. The most important goal of MMS is to conduct a definitive experiment to determine what causes magnetic field lines to reconnect in a collisionless plasma. The significance of the MMS results will extend far beyond the Earth's magnetosphere because reconnection is known to occur in interplanetary space and in the solar corona where it is responsible for solar flares and the disconnection events known as coronal mass ejections. Active research is also being conducted on reconnection in the laboratory and specifically in magnetic-confinement fusion devices in which it is a limiting factor in achieving and maintaining electron temperatures high enough to initiate fusion. Finally, reconnection is proposed as the cause of numerous phenomena throughout the universe such as comet-tail disconnection events, magnetar flares, supernova ejections, and dynamics of neutron-star accretion disks. The MMS mission design is focused on answering specific questions about reconnection at the Earth's magnetosphere. The prime focus of the mission is on determining the kinetic processes occurring in the electron diffusion region that are responsible for reconnection and that determine how it is initiated; but the mission will also place that physics into the context of the broad spectrum of physical processes associated with reconnection. Connections to other disciplines such as solar physics, astrophysics, and laboratory plasma physics are expected to be made through theory and modeling as informed by the MMS results.

  1. Dynamic Particle Injections in the Magnetospheres of the Solar System

    Science.gov (United States)

    Mauk, B.

    2014-12-01

    The occurrence of dynamic, planetward injections of plasma and energetic particles on the nightside magnetosphere is one of the defining characteristics of magnetospheric substorms at Earth. And yet, with the exploration of the solar system with planetary probes, it has become clear that dynamic planetward injections are if fact a ubiquitous characteristic of most strongly magnetized planets; only Neptune did not reveal the signatures of such processes when visited. But, within this diversity of magnetospheric environments, it is clear that the driving forces associated with injections can be very different from those at Earth. Jupiter, for example, is known to be powered by planetary rotation rather than the solar wind. Saturn has injections that are clearly powered by rotations, but it also has nightside injections that are, at minimum, triggered by solar wind events if not powered by the solar wind. Even for those magnetospheres clearly powered by rotation, there appears to be substantial similarity between the physical processes involved with the extraterrestrial planetary injections and recent formulations of injections within Earth's near-Earth magnetotail. With a focus on comparisons between Earth, Jupiter, Saturn, Uranus and Neptune, I here review the state of understanding generally of injections within extraterrestrial planets and what the comparisons might tell us about our understanding of substorm phenomena at Earth.

  2. Jupiter's Dynamic Magnetosphere

    Science.gov (United States)

    Vogt, M. F.; Bunce, E. J.; Kronberg, E. A.; Jackman, C. M.

    2014-12-01

    Jupiter's magnetosphere is a highly dynamic environment. Hundreds of reconnection events have been identified in Jupiter's magnetotail through analysis of magnetic field and particle measurements collected by the Galileo spacecraft. Quasi-periodic behavior, suggestive of reconnection, has been intermittently observed on a ~2-3 day time scale in several data sets, including magnetic field dipolarizations, flow bursts, auroral polar dawn spots, and the hectometric radio emission. In this paper we review the present state of knowledge of Jovian magnetospheric dynamics. Throughout the discussion, we highlight similarities and differences to Saturn's magnetosphere. For example, recent analysis of plasmoid signatures at both Jupiter and Saturn has established the role of tail reconnection in the overall mass and flux transport in the outer planet magnetospheres. The results for both Jupiter and Saturn suggest that the observed mass loss rate due to tail reconnection and plasmoid release is insufficient to account for the mass input rate from the moons Io and Enceladus, respectively. We also present new analysis in which we use the Michigan mSWiM propagated solar wind MHD model to estimate the solar wind conditions upstream of Jupiter. This information allows us to determine whether reconnection events occur preferentially during certain solar wind conditions, or whether there is evidence that the solar wind modulates the quasi-periodicity seen in the field dipolarizations and flow bursts.

  3. The Pulsating Pulsar Magnetosphere

    CERN Document Server

    Tsui, K H

    2015-01-01

    Following the basic principles of a charge separated pulsar magnetosphere \\citep{goldreich1969}, we consider the magnetosphere be stationary in space, instead of corotating, and the electric field be uploaded from the potential distribution on the pulsar surface, set up by the unipolar induction. Consequently, the plasma of the magnetosphere undergoes guiding center drifts of the gyro motion due to the transverse forces to the magnetic field. These forces are the electric force, magnetic gradient force, and field line curvature force. Since these plasma velocities are of drift nature, there is no need to introduce an emf along the field lines, which would contradict the $E_{\\parallel}=\\vec E\\cdot\\vec B=0$ plasma condition. Furthermore, there is also no need to introduce the critical field line separating the electron and ion open field lines. We present a self-consistent description where the magnetosphere is described in terms of electric and magnetic fields and also in terms of plasma velocities. The fields...

  4. Solar wind controls on Mercury's magnetospheric cusp

    Science.gov (United States)

    He, Maosheng; Vogt, Joachim; Heyner, Daniel; Zhong, Jun

    2017-04-01

    Mercury's magnetospheric cusp results from the interaction between the planetary intrinsic magnetic field and the solar wind. In this study, we assemble 2848 orbits of MESSENGER data for a comprehensive assessment of solar wind control on Mercury's cusp. We propose and validate an IMF estimation approach for the cusp transit, and construct an index to measure the magnetic disturbance. The index maximizes within the cusp, more intense than in the adjacent magnetosphere by several orders of magnitude. We develop an empirical model of the index as a function of IMFvector and Mercury's solar orbital phase. The model is used to study the cusp activity under different conditions. Comparisons reveal the cusp activity is more intense and extends further in local time, under antisunward IMF (IMFx0), under southward IMF (IMFz0), and when Mercury orbits at its perihelion than at aphelion. Besides, the cusp shifts azimuthally towards dawn when IMF reverses from westward (IMFy0), and when Mercury approaches its perihelion. The IMFx dependence is consistent with existing observations and simulations which are ascribed to the asymmetry of dayside magnetospheric configuration between sunward and anti-sunward IMF conditions. We explain the IMFy and IMFz dependences in terms of component reconnection of the magnetospheric field merging with By-dominant and Bz-dominant IMF, respectively. The control of the Mercury solar orbit phase on the intensity and local time location of the disturbance peak are possibly arising from the modulations of the heliocentric distance on the solar wind ram pressure. The existence of significant IMF dependence suggests the IMF orientation plays a role in the convection configuration at Mercury. The IMFy-dependence at Mercury is opposite to that at Earth, suggesting that component reconnection at the dayside magnetopause is more important in the Hermean system than in the terrestrial one. This also implies that reconnection occurs at lower magnetic shear

  5. The electromagnetic field for an open magnetosphere

    Science.gov (United States)

    Heikkila, W. J.

    1984-01-01

    The boundary-layer-dominated models of the earth EM field developed by Heikkila (1975, 1978, 1982, and 1983) and Heikkila et al. (1979) to account for deficiencies in the electric-field descriptions of quasi-steady-state magnetic-field-reconnection models (such as that of Cowley, 1980) are characterized, reviewing the arguments and indicating the most important implications. The mechanisms of boundary-layer formation and field direction reversal are explained and illustrated with diagrams, and it is inferred that boundary-layer phenomena rather than magnetic reconnection may be the cause of large-scale magnetospheric circulation, convection, plasma-sheet formation and sunward convection, and auroras, the boundary layer acting basically as a viscous process mediating solar-wind/magnetosphere interactions.

  6. Inner magnetosphere coupling: Recent advances

    Science.gov (United States)

    Usanova, M. E.; Shprits, Y. Y.

    2017-01-01

    The dynamics of the inner magnetosphere is strongly governed by the interactions between different plasma populations that are coupled through large-scale electric and magnetic fields, currents, and wave-particle interactions. Inner magnetospheric plasma undergoes self-consistent interactions with global electric and magnetic fields. Waves excited in the inner magnetosphere from unstable particle distributions can provide energy exchange between different particle populations in the inner magnetosphere and affect the ring current and radiation belt dynamics. The ionosphere serves as an energy sink and feeds the magnetosphere back through the cold plasma outflow. The precipitating inner magnetospheric particles influence the ionosphere and upper atmospheric chemistry and affect climate. Satellite measurements and theoretical studies have advanced our understanding of the dynamics of various plasma populations in the inner magnetosphere. However, our knowledge of the coupling processes among the plasmasphere, ring current, radiation belts, global magnetic and electric fields, and plasma waves generated within these systems is still incomplete. This special issue incorporates extended papers presented at the Inner Magnetosphere Coupling III conference held 23-27 March 2015 in Los Angeles, California, USA, and includes modeling and observational contributions addressing interactions within different plasma populations in the inner magnetosphere (plasmasphere, ring current, and radiation belts), coupling between fields and plasma populations, as well as effects of the inner magnetosphere on the ionosphere and atmosphere.

  7. Stellar wind-magnetosphere interaction at exoplanets: computations of auroral radio powers

    CERN Document Server

    Nichols, J D

    2016-01-01

    We present calculations of the auroral radio powers expected from exoplanets with magnetospheres driven by an Earth-like magnetospheric interaction with the solar wind. Specifically, we compute the twin cell-vortical ionospheric flows, currents, and resulting radio powers resulting from a Dungey cycle process driven by dayside and nightside magnetic reconnection, as a function of planetary orbital distance and magnetic field strength. We include saturation of the magnetospheric convection, as observed at the terrestrial magnetosphere, and we present power law approximations for the convection potentials, radio powers and spectral flux densities. We specifically consider a solar-age system and a young (1 Gyr) system. We show that the radio power increases with magnetic field strength for magnetospheres with saturated convection potential, and broadly decreases with increasing orbital distance. We show that the magnetospheric convection at hot Jupiters will be saturated, and thus unable to dissipate the full av...

  8. Electrodynamics of pulsar magnetospheres

    CERN Document Server

    Cerutti, Benoît

    2016-01-01

    We review electrodynamics of rotating magnetized neutron stars, from the early vacuum model to recent numerical experiments with plasma-filled magnetospheres. Significant progress became possible due to the development of global particle-in-cell simulations which capture particle acceleration, emission of high-energy photons, and electron-positron pair creation. The numerical experiments show from first principles how and where electric gaps form, and promise to explain the observed pulsar activity from radio waves to gamma-rays.

  9. Saturn's magnetospheric refresh rate

    Science.gov (United States)

    Rymer, A. M.; Mitchell, D. G.; Hill, T. W.; Kronberg, E. A.; Krupp, N.; Jackman, C. M.

    2013-06-01

    A 2-3 day periodicity observed in Jupiter's magnetosphere (superposed on the giant planet's 9.5 h rotation rate) has been associated with a characteristic mass-loading/unloading period at Jupiter. We follow a method derived by Kronberg et al. () and find, consistent with their results, that this period is most likely to fall between 1.5 and 3.9 days. Assuming the same process operates at Saturn, we argue, based on equivalent scales at the two planets, that its period should be 4 to 6 times faster at Saturn and therefore display a period of 8 to 18 h. Applying the method of Kronberg et al. for the mass-loading source rates estimated by Smith et al. () based on data from the third and fifth Cassini-Enceladus encounters, we estimate that the expected magnetospheric refresh rate varies from 8 to 31 h, a range that includes Saturn's rotation rate of ~10.8 h. The magnetospheric period we describe is proportional to the total mass-loading rate in the system. The period is, therefore, faster (1) for increased outgassing from Enceladus, (2) near Saturn solstice (when the highest proportion of the rings is illuminated), and (3) near solar maximum when ionization by solar photons maximizes. We do not claim to explain the few percent jitter in period derived from Saturn Kilometric Radiation with this model, nor do we address the observed difference in period observed in the north and south hemispheres.

  10. AXIOM: Advanced X-ray Imaging of the Magnetosphere

    Science.gov (United States)

    Branduardi-Raymont, G.; Sembay, S. F.; Eastwood, J. P.; Sibeck, D. G.; Abbey, A.; Brown, P.; Carter, J. A.; Carr, C. M.; Forsyth, C.; Kataria, D.; Kemble, S.; Milan, S. E.; Owen, C. J.; Peacocke, L.; Read, A. M.; Coates, A. J.; Collier, M. R.; Cowley, S. W. H.; Fazakerley, A. N.; Fraser, G. W.; Jones, G. H.; Lallement, R.; Lester, M.; Porter, F. S.; Yeoman, T. K.

    2012-01-01

    Planetary plasma and magnetic field environments can be studied in two complementary ways - by in situ measurements, or by remote sensing. While the former provide precise information about plasma behaviour, instabilities and dynamics on local scales, the latter offers the global view necessary to understand the overall interaction of the magnetospheric plasma with the solar wind. Some parts of the Earth's magnetosphere have been remotely sensed, but the majority remains unexplored by this type of measurements. Here we propose a novel and more elegant approach employing remote X-ray imaging techniques. which are now possible thanks to the relatively recent discovery of solar wind charge exchange X-ray emissions in the vicinity of the Earth's magnetosphere. In this article we describe how an appropriately designed and located. X-ray telescope, supported by simultaneous in situ measurements of the solar wind, can be used to image the dayside magnetosphere, magnetosheath and bow shock. with a temporal and spatial resolution sufficient to address several key outstanding questions concerning how the solar wind interacts with the Earth's magnetosphere on a global level. Global images of the dayside magnetospheric boundaries require vantage points well outside the magnetosphere. Our studies have led us to propose 'AXIOM: Advanced X-ray Imaging Of the Magnetosphere', a concept mission using a Vega launcher with a LISA Pathfinder-type Propulsion Module to place the spacecraft in a Lissajous orbit around the Earth - Moon Ll point. The model payload consists of an X-ray Wide Field Imager, capable of both imaging and spectroscopy, and an in situ plasma and magnetic field measurement package. This package comprises a Proton-Alpha Sensor, designed to measure the bulk properties of the solar wind, an Ion Composition Analyser, to characterize the minor ion populations in the solar wind that cause charge exchange emission, and a Magnetometer, designed to measure the strength and

  11. A numerical code for a three-dimensional magnetospheric MHD equilibrium model

    Science.gov (United States)

    Voigt, G.-H.

    1992-01-01

    Two dimensional and three dimensional MHD equilibrium models were begun for Earth's magnetosphere. The original proposal was motivated by realizing that global, purely data based models of Earth's magnetosphere are inadequate for studying the underlying plasma physical principles according to which the magnetosphere evolves on the quasi-static convection time scale. Complex numerical grid generation schemes were established for a 3-D Poisson solver, and a robust Grad-Shafranov solver was coded for high beta MHD equilibria. Thus, the effects were calculated of both the magnetopause geometry and boundary conditions on the magnetotail current distribution.

  12. Probing the long tail of the magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Kerr, R.A.

    1984-12-14

    Using data from the International Sun-Earth Explorer Spacecraft (ISEE-3), researchers have studied the structure of the magnetotail and its behavior. In the plasma sheet of the distant tail, ISEE-3 found plasma flowing tailward as fast as 1000 Km/sec. An ISEE-3 group at Los Alamos National Laboratory has offered an explanation of the high plasma speeds that addresses how the magnetosphere stores and ultimately rids itself of the charged particles and magnetic fields that it picks up from the solar wind. According to this group the high tailward plasma sheet flows are driven by a process called magnetic reconnection.

  13. Origins Of Magnetospheric Physics An Expanded Edition

    CERN Document Server

    Van Allen, James A

    2004-01-01

    Early in 1958, instruments on the space satellites Explorer I and Explorer III revealed the presence of radiation belts, enormous populations of energetic particles trapped in the magnetic field of the earth. Originally published in 1983 but long out of print until now, Origins of Magnetospheric Physics tells the story of this dramatic and hugely transformative period in scientific and Cold War history. Writing in an accessible style and drawing on personal journals, correspondence, published papers, and the recollections of colleagues, James Van Allen documents a trail-blazing era in space hi

  14. Extremely Intense Magnetospheric Substorms : External Triggering? Preconditioning?

    Science.gov (United States)

    Tsurutani, Bruce; Echer, Ezequiel; Hajra, Rajkumar

    2016-07-01

    We study particularly intense substorms using a variety of near-Earth spacecraft data and ground observations. We will relate the solar cycle dependences of events, determine whether the supersubstorms are externally or internally triggered, and their relationship to other factors such as magnetospheric preconditioning. If time permits, we will explore the details of the events and whether they are similar to regular (Akasofu, 1964) substorms or not. These intense substorms are an important feature of space weather since they may be responsible for power outages.

  15. Equatorial magnetospheric particles and auroral precipitations

    Science.gov (United States)

    McIlwain, C. E.

    The injection boundary beyond which fresh hot plasma appears each magnetospheric substorm is generalized and extended to circle the Earth. The concept of an auroral shell representing the inner limit of active auroral processes is introduced. It is proposed that at low altitudes, this shell marks the equatorward edge of the auroral ovals, and that at high altitudes, it marks the injection boundary. The auroral ring is defined as the intersection of the auroral shell with the magnetic equator. A simple equation for computing the expected location of the auroral ring as a function of local time and magnetic disturbance level is obtained. Tests indicate that the model is valid and reasonably accurate.

  16. Saturn's Magnetosphere, Rings, and Inner Satellites.

    Science.gov (United States)

    VAN Allen, J A; Thomsen, M F; Randall, B A; Rairden, R L; Grosskreutz, C L

    1980-01-25

    Our 31 August to 5 September 1979 observations together with those of the other Pioneer 11 investigators provide the first credible discovery of the magnetosphere of Saturn and many detailed characteristics thereof. In physical dimensions and energetic charged particle population, Saturn's magnetosphere is intermediate between those of Earth and Jupiter. In terms of planetary radii, the scale of Saturn's magnetosphere more nearly resembles that of Earth and there is much less inflation by entrapped plasma than in the case at Jupiter. The orbit of Titan lies in the outer fringes of the magnetosphere. Particle angular distributions on the inbound leg of the trajectory (sunward side) have a complex pattern but are everywhere consistent with a dipolar magnetic field approximately perpendicular to the planet's equator. On the outbound leg (dawnside) there are marked departures from this situation outside of 7 Saturn radii (Rs), suggesting an equatorial current sheet having both longitudinal and radial components. The particulate rings and inner satellites have a profound effect on the distribution of energetic particles. We find (i) clear absorption signatures of Dione and Mimas; (ii) a broad absorption region encompassing the orbital radii of Tethys and Enceladus but probably attributable, at least in part, to plasma physical effects; (iii) no evidence for Janus (1966 S 1) (S 10) at or near 2.66 Rs; (iv) a satellite of diameter greater, similar 170 kilometers at 2.534 R(s) (1979 S 2), probably the same object as that detected optically by Pioneer 11 (1979 S 1) and previously by groundbased telescopes (1966 S 2) (S 11); (v) a satellite of comparable diameter at 2.343 Rs (1979 S 5); (vi) confirmation of the F ring between 2.336 and 2.371 Rs; (vii) confirmation of the Pioneer division between 2.292 and 2.336 Rs; (viii) a suspected satellite at 2.82 Rs (1979 S 3); (ix) no clear evidence for the E ring though its influence may be obscured by stronger effects; and (x) the

  17. Magnetospheric state of sawtooth events

    Science.gov (United States)

    Fung, Shing F.; Tepper, Julia A.; Cai, Xia

    2016-08-01

    Magnetospheric sawtooth events, first identified in the early 1990s, are named for their characteristic appearance of multiple quasiperiodic intervals of slow decrease followed by sharp increase of proton differential energy fluxes in the geosynchronous region. The successive proton flux oscillations have been interpreted as recurrences of stretching and dipolarization of the nightside geomagnetic field. Due to their often extended intervals with 2-10 cycles, sawteeth occurrences are sometimes referred to as a magnetospheric mode. While studies of sawtooth events over the past two decades have yielded a wealth of information about such events, the magnetospheric state conditions for the occurrence of sawtooth events and how sawtooth oscillations may depend on the magnetospheric state conditions remain unclear. In this study, we investigate the characteristic magnetospheric state conditions (specified by Psw interplanetary magnetic field (IMF) Btot, IMF Bz Vsw, AE, Kp and Dst, all time shifted with respect to one another) associated with the intervals before, during, and after sawteeth occurrences. Applying a previously developed statistical technique, we have determined the most probable magnetospheric states propitious for the development and occurrence of sawtooth events, respectively. The statistically determined sawtooth magnetospheric state has also been validated by using out-of-sample events, confirming the notion that sawtooth intervals might represent a particular global state of the magnetosphere. We propose that the "sawtooth state" of the magnetosphere may be a state of marginal stability in which a slight enhancement in the loading rate of an otherwise continuous loading process can send the magnetosphere into the marginally unstable regime, causing it to shed limited amount of energy quickly and return to the marginally stable regime with the loading process continuing. Sawtooth oscillations result as the magnetosphere switches between the marginally

  18. The magnetosphere under weak solar wind forcing

    Directory of Open Access Journals (Sweden)

    C. J. Farrugia

    2007-02-01

    Full Text Available The Earth's magnetosphere was very strongly disturbed during the passage of the strong shock and the following interacting ejecta on 21–25 October 2001. These disturbances included two intense storms (Dst*≈−250 and −180 nT, respectively. The cessation of this activity at the start of 24 October ushered in a peculiar state of the magnetosphere which lasted for about 28 h and which we discuss in this paper. The interplanetary field was dominated by the sunward component [B=(4.29±0.77, −0.30±0.71, 0.49±0.45 nT]. We analyze global indicators of geomagnetic disturbances, polar cap precipitation, ground magnetometer records, and ionospheric convection as obtained from SuperDARN radars. The state of the magnetosphere is characterized by the following features: (i generally weak and patchy (in time low-latitude dayside reconnection or reconnection poleward of the cusps; (ii absence of substorms; (iii a monotonic recovery from the previous storm activity (Dst corrected for magnetopause currents decreasing from ~−65 to ~−35 nT, giving an unforced decreased of ~1.1 nT/h; (iv the probable absence of viscous-type interaction originating from the Kelvin-Helmholtz (KH instability; (v a cross-polar cap potential of just 20–30 kV; (vi a persistent, polar cap region containing (vii very weak, and sometimes absent, electron precipitation and no systematic inter-hemisphere asymmetry. Whereas we therefore infer the presence of a moderate amount of open flux, the convection is generally weak and patchy, which we ascribe to the lack of solar wind driver. This magnetospheric state approaches that predicted by Cowley and Lockwood (1992 but has never yet been observed.

  19. Predicting the Reaction of the Magnetosphere-Ionosphere System to Driving by the Solar Wind: A Global Correlation Approach

    Science.gov (United States)

    Borovsky, J.; Denton, M.

    2016-12-01

    Using canonical correlation analysis (CCA) we are looking at the correlation patterns between the multi-variable solar-wind data set and an Earth data set of comprised of multiple measures of the state of the magnetosphere (geomagnetic indices and other indices). We will treat the Earth data set as a "stock market" and we define a "stock-market index". The primary correlation in the composite solar-wind-magnetosphere system yields a very accurate prediction of the reaction of the "index" to the solar wind, and the magnetosphere's reaction shows a remarkable degree of linearity with solar-wind parameters. Secondary correlations in the composite solar-wind-magnetosphere system show different modes of reaction of the magnetosphere to the solar wind. The CCA methodology highlights a physics versus mathematics dilemma in discerning how the solar wind drives the magnetosphere.

  20. Pulsar Magnetospheres and Pulsar Winds

    CERN Document Server

    Beskin, Vasily S

    2016-01-01

    Surprisingly, the chronology of nearly 50 years of the pulsar magnetosphere and pulsar wind research is quite similar to the history of our civilization. Using this analogy, I have tried to outline the main results obtained in this field. In addition to my talk, the possibility of particle acceleration due to different processes in the pulsar magnetosphere is discussed in more detail.

  1. Low Energy Cosmic Rays and the Disturbed Magnetosphere

    CERN Document Server

    Kudela, K

    2013-01-01

    Low energy galactic cosmic rays as well as particles accelerated to high energies either at the solar surface or in the interplanetary medium have access to the atmosphere above a given position on the Earth depending upon the state of the magnetosphere. The interpretation of the cosmic ray anisotropy, deduced from the neutron monitor (NM) network, must assume the variability of the magnetospheric configuration. Along with a short review of changes of the geomagnetic cutoffs in the disturbed magnetosphere reported in the earlier papers, we present the results of computations of transmissivity function and asymptotic directions for selected points on the ground and for a low altitude polar orbiting satellite as well. The computations, based on different available models of geomagnetic field of external sources are performed for quiet time periods and for strong geomagnetic disturbances occurred in 2003 and 2004.

  2. Magnetospheres of massive stars

    Science.gov (United States)

    Küker, M.

    We study the interaction of line-driven winds from massive stars with the magnetic field rooted in these stars by carrying out numerical simulations using the Nirvana MHD code in 2D in spherical polar coordinates. The code's adaptive mesh refinement feature allows high spatial resolution across the whole simulation box. We study both O and Wolf-Rayet stars for a range of magnetic field strengths from weak to strong as measured by the confinement parameter. For weak fields our simulations show that the initially dipolar field opens up far away from the star and a thin disk-like structure forms in the equatorial plane of the magnetic field. For stronger fields the disk is disrupted close to the stellar surface and closed field lines persist at low latitudes. For very strong fields a pronounced magnetosphere forms where the gas is forced to move along the field lines and eventually falls back to the stellar surface.

  3. The Magnetospheric Multiscale Constellation

    Science.gov (United States)

    Tooley, C. R.; Black, R. K.; Robertson, B. P.; Stone, J. M.; Pope, S. E.; Davis, G. T.

    2016-03-01

    The Magnetospheric Multiscale (MMS) mission is the fourth mission of the Solar Terrestrial Probe (STP) program of the National Aeronautics and Space Administration (NASA). The MMS mission was launched on March 12, 2015. The MMS mission consists of four identically instrumented spin-stabilized observatories which are flown in formation to perform the first definitive study of magnetic reconnection in space. The MMS mission was presented with numerous technical challenges, including the simultaneous construction and launch of four identical large spacecraft with 100 instruments total, stringent electromagnetic cleanliness requirements, closed-loop precision maneuvering and pointing of spinning flexible spacecraft, on-board GPS based orbit determination far above the GPS constellation, and a flight dynamics design that enables formation flying with separation distances as small as 10 km. This paper describes the overall mission design and presents an overview of the design, testing, and early on-orbit operation of the spacecraft systems and instrument suite.

  4. Hot Jupiter Magnetospheres

    CERN Document Server

    Trammell, George B; Li, Zhi-Yun

    2010-01-01

    (Abridged) The upper atmospheres of close-in gas giant exoplanets are subjected to intense heating/tidal forces from their parent stars. Atomic/ionized hydrogen (H) layers are sufficiently rarefied that magnetic pressure may dominate gas pressure for expected planetary magnetic field strength. We examine the magnetospheric structure using a 3D isothermal magnetohydrodynamic model that includes: a static "dead zone" near the magnetic equator containing magnetically confined gas; a "wind zone" outside the magnetic equator in which thermal pressure gradients and the magneto-centrifugal-tidal effect give rise to transonic outflow; and a region near the poles where sufficiently strong tidal forces may suppress transonic outflow. Using dipole field geometry, we estimate the size of the dead zone to be ~1-10 planetary radii for a range of parameters. To understand appropriate base conditions for the 3D isothermal model, we compute a 1D thermal model in which photoelectric heating from the stellar Lyman continuum is ...

  5. Solar wind entry into the high-latitude terrestrial magnetosphere during geomagnetically quiet times.

    Science.gov (United States)

    Shi, Q Q; Zong, Q-G; Fu, S Y; Dunlop, M W; Pu, Z Y; Parks, G K; Wei, Y; Li, W H; Zhang, H; Nowada, M; Wang, Y B; Sun, W J; Xiao, T; Reme, H; Carr, C; Fazakerley, A N; Lucek, E

    2013-01-01

    An understanding of the transport of solar wind plasma into and throughout the terrestrial magnetosphere is crucial to space science and space weather. For non-active periods, there is little agreement on where and how plasma entry into the magnetosphere might occur. Moreover, behaviour in the high-latitude region behind the magnetospheric cusps, for example, the lobes, is poorly understood, partly because of lack of coverage by previous space missions. Here, using Cluster multi-spacecraft data, we report an unexpected discovery of regions of solar wind entry into the Earth's high-latitude magnetosphere tailward of the cusps. From statistical observational facts and simulation analysis we suggest that these regions are most likely produced by magnetic reconnection at the high-latitude magnetopause, although other processes, such as impulsive penetration, may not be ruled out entirely. We find that the degree of entry can be significant for solar wind transport into the magnetosphere during such quiet times.

  6. A comprehensive model of the quiet-time, near-Earth magnetic field: phase 3

    DEFF Research Database (Denmark)

    Sabaka, T.J.; Olsen, Nils; Langel, R.A.

    2002-01-01

    The near-Earth magnetic field is caused by sources in the Earth's core, ionosphere, magnetosphere, lithosphere and from coupling currents between the ionosphere and the magnetosphere, and between hemispheres. Traditionally, the main field (low degree internal field) and magnetospheric field have......, and includes an accounting for main field influences on the magnetosphere, main field and solar activity influences on the ionosphere, seasonal influences on the coupling currents, a priori characterization of the influence of the ionosphere and the magnetosphere on Earth-induced fields, and an explicit...

  7. Hydromagnetic Waves in the Magnetosphere and the Ionosphere

    CERN Document Server

    Alperovich, Leonid S

    2007-01-01

    The book deals with Ultra-Low-Frequency (ULF)-electromagnetic waves observed on Earth and in Space. These are so-called geomagnetic variations or pulsations. Alfvén's discovery related to the influence of the strong magnetic field on the conducting fluids (magnetohydrodynamics) led to development of the concept that the ULF-waves are magnetospheric magnetohydrodynamic (MHD)-waves. MHD-waves at their propagation gather information about the magnetosphere, ionosphere, and the ground. There are two applied aspects based on using the ULF electromagnetic oscillations. The first one is the ground-based diagnostics of the magnetosphere. This is an attempt to monitor in the real time the magnetosphere size, distance to the last closed field-lines, distribution of the cold plasma, etc. The second one is the deep electromagnetic sounding of the Earth. The basis for these studies is the capability of any electromagnetic wave to penetrate a conductor to a finite depth. The ULF-waves can reach the depth of a few hundred ...

  8. Tethys and Dione as sources of outward-flowing plasma in Saturn's magnetosphere.

    Science.gov (United States)

    Burch, J L; Goldstein, J; Lewis, W S; Young, D T; Coates, A J; Dougherty, M K; André, N

    2007-06-14

    Rotating at over twice the angular speed of Earth, Saturn imposes a rapid spin on its magnetosphere. As a result, cold, dense plasma is believed to be flung outward from the inner magnetosphere by centrifugal force and replaced by hotter, more tenuous plasma from the outer magnetosphere. The centrifugal interchange of plasmas in rotating magnetospheres was predicted many years ago and was conclusively demonstrated by observations in Jupiter's magnetosphere, which--like that of Saturn (but unlike that of Earth)--is rotationally dominated. Recent observations in Saturn's magnetosphere have revealed narrow injections of hot, tenuous plasma believed to be the inward-moving portion of the centrifugal interchange cycle. Here we report observations of the distribution of the angle between the electron velocity vector and the magnetic field vector ('pitch angle') obtained in the cold, dense plasma adjacent to these inward injection regions. The observed pitch-angle distributions are indicative of outward plasma flow and consistent with centrifugal interchange in Saturn's magnetosphere. Further, we conclude that the observed double-peaked ('butterfly') pitch-angle distributions result from the transport of plasma from regions near the orbits of Dione and Tethys, supporting the idea of distinct plasma tori associated with these moons.

  9. The Magnetospheric Multiscale Magnetometers

    Science.gov (United States)

    Russell, C. T.; Anderson, B. J.; Baumjohann, W.; Bromund, K. R.; Dearborn, D.; Fischer, D.; Le, G.; Leinweber, H. K.; Leneman, D.; Magnes, W.; Means, J. D.; Moldwin, M. B.; Nakamura, R.; Pierce, D.; Plaschke, F.; Rowe, K. M.; Slavin, J. A.; Strangeway, R. J.; Torbert, R.; Hagen, C.; Jernej, I.; Valavanoglou, A.; Richter, I.

    2016-03-01

    The success of the Magnetospheric Multiscale mission depends on the accurate measurement of the magnetic field on all four spacecraft. To ensure this success, two independently designed and built fluxgate magnetometers were developed, avoiding single-point failures. The magnetometers were dubbed the digital fluxgate (DFG), which uses an ASIC implementation and was supplied by the Space Research Institute of the Austrian Academy of Sciences and the analogue magnetometer (AFG) with a more traditional circuit board design supplied by the University of California, Los Angeles. A stringent magnetic cleanliness program was executed under the supervision of the Johns Hopkins University's Applied Physics Laboratory. To achieve mission objectives, the calibration determined on the ground will be refined in space to ensure all eight magnetometers are precisely inter-calibrated. Near real-time data plays a key role in the transmission of high-resolution observations stored on board so rapid processing of the low-resolution data is required. This article describes these instruments, the magnetic cleanliness program, and the instrument pre-launch calibrations, the planned in-flight calibration program, and the information flow that provides the data on the rapid time scale needed for mission success.

  10. MESSENGER observations of magnetic reconnection in Mercury's magnetosphere.

    Science.gov (United States)

    Slavin, James A; Acuña, Mario H; Anderson, Brian J; Baker, Daniel N; Benna, Mehdi; Boardsen, Scott A; Gloeckler, George; Gold, Robert E; Ho, George C; Korth, Haje; Krimigis, Stamatios M; McNutt, Ralph L; Raines, Jim M; Sarantos, Menelaos; Schriver, David; Solomon, Sean C; Trávnícek, Pavel; Zurbuchen, Thomas H

    2009-05-01

    Solar wind energy transfer to planetary magnetospheres and ionospheres is controlled by magnetic reconnection, a process that determines the degree of connectivity between the interplanetary magnetic field (IMF) and a planet's magnetic field. During MESSENGER's second flyby of Mercury, a steady southward IMF was observed and the magnetopause was threaded by a strong magnetic field, indicating a reconnection rate ~10 times that typical at Earth. Moreover, a large flux transfer event was observed in the magnetosheath, and a plasmoid and multiple traveling compression regions were observed in Mercury's magnetotail, all products of reconnection. These observations indicate that Mercury's magnetosphere is much more responsive to IMF direction and dominated by the effects of reconnection than that of Earth or the other magnetized planets.

  11. Magnetospheric MultiScale (MMS) System Manager

    Science.gov (United States)

    Schiff, Conrad; Maher, Francis Alfred; Henely, Sean Philip; Rand, David

    2014-01-01

    The Magnetospheric MultiScale (MMS) mission is an ambitious NASA space science mission in which 4 spacecraft are flown in tight formation about a highly elliptical orbit. Each spacecraft has multiple instruments that measure particle and field compositions in the Earths magnetosphere. By controlling the members relative motion, MMS can distinguish temporal and spatial fluctuations in a way that a single spacecraft cannot.To achieve this control, 2 sets of four maneuvers, distributed evenly across the spacecraft must be performed approximately every 14 days. Performing a single maneuver on an individual spacecraft is usually labor intensive and the complexity becomes clearly increases with four. As a result, the MMS flight dynamics team turned to the System Manager to put the routine or error-prone under machine control freeing the analysts for activities that require human judgment.The System Manager is an expert system that is capable of handling operations activities associated with performing MMS maneuvers. As an expert system, it can work off a known schedule, launching jobs based on a one-time occurrence or on a set reoccurring schedule. It is also able to detect situational changes and use event-driven programming to change schedules, adapt activities, or call for help.

  12. Modeling plasma pressure anisotropy's effect on Saturn's global magnetospheric dynamics

    Science.gov (United States)

    Tilley, M.; Harnett, E. M.; Winglee, R.

    2014-12-01

    A 3D multi-fluid, multi-scale plasma model with a complete treatment of plasma pressure anisotropy is employed to study global magnetospheric dynamics at Saturn. Cassini has observed anisotropies in the Saturnian magnetosphere, and analyses have showed correlations between anisotropy and plasma convection, ring current structure and intensity, confinement of plasma to the equatorial plane, as well as mass transport to the outer magnetosphere. The energization and transport of plasma within Saturn's magnetosphere is impactful upon the induced magnetic environments and atmospheres of potentially habitable satellites such as Enceladus and Titan. Recent efforts to couple pressure anisotropy with 3D multi-fluid plasma modeling have shown a significant move towards matching observations for simulations of Earth's magnetosphere. Our approach is used to study the effects of plasma pressure anisotropy on global processes of the Saturnian magnetosphere such as identifying the effect of pressure anisotropy on the centrifugal interchange instability. Previous simulation results have not completely replicated all aspects of the structure and formation of the interchange 'fingers' measured by Cassini at Saturn. The related effects of anisotropy, in addition to those mentioned above, include contribution to formation of MHD waves (e.g. reduction of Alfvén wave speed) and formation of firehose and mirror instabilities. An accurate understanding of processes such as the interchange instability is required if a complete picture of mass and energy transport at Saturn is to be realized. The results presented here will detail how the inclusion of a full treatment of pressure anisotropy for idealized solar wind conditions modifies the interchange structure and shape of the tail current sheet. Simulation results are compared to observations made by Cassini.

  13. Shrinkage of magnetosphere observed by TC-1 satellite during the high-speed solar wind stream

    Institute of Scientific and Technical Information of China (English)

    LI LiuYuan; CAO JinBin; ZHOU GuoCheng; YANG JunYing; YAN ChunXiao; ZHANG TieLong; H. REME; I. DANDOURAS; C. M. CARR

    2008-01-01

    During the interval 06:14-07:30 UT on August 24, 2005, since the Earth's magneto-pause was suddenly compressed by the persistent high-speed solar wind stream with the southward component of the interplanetary magnetic field (IMF), the magnetopause moved Inward for about 3.1 RE. Meanwhile, TC-1 satellite shifted from northern plasma sheet to the northern lobe/mantle region, although it kept Inward flying during the Interval 06:00-07:30UT. The shift of TC-1 from the plasma sheet to the lobe/mantle is caused by the simultaneous inward displacements of the plasma sheet and near-Earth lobe/mantle region, and their inward movement velocity is larger than the inward motion velocity of TC-1. The Joint inward dis-placements of the magnetopause, the lobe/mantle region and the plasma sheet indicate that the whole magnetosphere shrinks inward due to the magnetospheric compression by the high-speed solar wind stream, and the magnetospheric ions are attached to the magnetic field lines (i.e. 'frozen' in magnetic field) and move inward in the shrinking process of magnetosphere. The large shrinkage of magne-tosphere indicates that the near-Earth magnetotail compression caused by the strong solar wind dynamic pressure is much larger than its thickening caused by the southward component of the IMF, and the locations of magnetospheric regions with different plasmas vary remarkably with the variation of the solar wind dynamic pressure.

  14. Open flux in Saturn’s magnetosphere

    Science.gov (United States)

    Badman, Sarah V.; Jackman, Caitriona M.; Nichols, Jonathan D.; Clarke, John T.; Gérard, Jean-Claude

    2014-03-01

    We characterise the interaction between the solar wind and Saturn’s magnetosphere by evaluating the amount of ‘open’ magnetic flux connected to the solar wind. This is deduced from a large set of Hubble Space Telescope images of the ultraviolet aurora, using the poleward boundary of the main aurora as a proxy for the open-closed field line boundary in the ionosphere. The amount of open flux is found to be 10-50 GWb, with a mean of 35 GWb. The typical change in open flux between consecutive observations separated by 10-60 h is -5 or +7 GWb. These changes are a result of imbalance between open flux creation at the dayside magnetopause and its closure in the magnetotail. The 5 GWb typical decrease in open flux is consistent with in situ measurements of the flux transported following a reconnection event. Estimates of average, net reconnection rates are found to be typically a few tens of kV, with some extreme examples of unbalanced magnetopause or tail reconnection occurring at ∼300 kV. The range of values determined suggest that Saturn’s magnetosphere does not generally achieve a steady state between flux opening at the magnetopause and flux closure in the magnetotail. The percentage of magnetic flux which is open in Saturn’s magnetosphere is similar to that measured at the Earth (2-11%), but the typical percentage that is closed between observations is significantly lower (13% compared to 40-70%). Therefore, open flux is usually closed in smaller (few GWb) events in Saturn’s magnetosphere. The exception to this behaviour is large, rapid flux closure events which are associated with solar wind compressions. While the rates of flux opening and closure should be equal over long timescales, they are evidently different on shorter (up to tens of hours) timescales. The relative independence of the magnetopause and tail reconnection rates can be attributed to the long loading timescales required to transport open field lines into the tail.

  15. The physics of thermal plasma in the magnetosphere; Proceedings of Symposium 9 of the 26th COSPAR Plenary Meeting, Toulouse, France, June 30-July 11, 1986

    Science.gov (United States)

    Chappell, C. R. (Editor); Gringauz, K. I. (Editor)

    1986-01-01

    The conference presents papers on the shape, dynamics, and thermal structure of the plasmasphere and plasmapause; the ionosphere as a supplier of plasma to the earth's magnetosphere; the modeling and remote sensing of thermal plasma in the earth's magnetosphere; and magnetospheric cold plasmas as a medium for wave generation and propagation. Particular attention is given to whistler studies of plasmasphere shape and dynamics, plasmasphere thermal structure as measured by ISEE-1 and DE-1, low-energy ion flows into the magnetosphere, field-aligned flows of ionospheric plasma in the magnetosphere, and field-aligned plasmaspheric flows at moderate latitudes. Papers are also presented on the effects of a tailward stretching geomagnetic field on the drift motion of plasma particles in the magnetospheric equatorial plane, ion cyclotron waves observed near the plasmapause, and the response of energetic particles to nightside magnetic pulsations as seen by AMPTE/CCE.

  16. The Sun and Earth

    Science.gov (United States)

    Gopalswamy, Natchimuthuk

    2012-01-01

    Thus the Sun forms the basis for life on Earth via the black body radiation it emits. The Sun also emits mass in the form of the solar wind and the coronal mass ejections (CMEs). Mass emission also occurs in the form of solar energetic particles (SEPs), which happens during CMEs and solar flares. Both the mass and electromagnetic energy output of the Sun vary over a wide range of time scales, thus introducing disturbances on the space environment that extends from the Sun through the entire heliosphere including the magnetospheres and ionospheres of planets and moons of the solar system. Although our habitat is located in the neutral atmosphere of Earth, we are intimately connected to the non-neutral space environment starting from the ionosphere to the magnetosphere and to the vast interplanetary space. The variability of the solar mass emissions results in the interaction between the solar wind plasma and the magnetospheric plasma leading to huge disturbances in the geospace. The Sun ionizes our atmosphere and creates the ionosphere. The ionosphere can be severely disturbed by the transient energy input from solar flares and the solar wind during geomagnetic storms. The complex interplay between Earth's magnetic field and the solar magnetic field carried by the solar wind presents varying conditions that are both beneficial and hazardous to life on earth. This seminar presents some of the key aspects of this Sun-Earth connection that we have learned since the birth of space science as a scientific discipline some half a century ago.

  17. Solar wind energy transfer through the magnetopause of an open magnetosphere

    Science.gov (United States)

    Lee, L. C.; Roederer, J. G.

    1982-01-01

    An expression is derived for the total power, transferred from the solar wind to an open magnetosphere, which consists of the electromagnetic energy rate and the particle kinetic energy rate. The total rate of energy transferred from the solar wind to an open magnetosphere mainly consists of kinetic energy, and the kinetic energy flux is carried by particles, penetrating from the solar wind into the magnetosphere, which may contribute to the observed flow in the plasma mantle and which will eventually be convected slowly toward the plasma sheet by the electric field as they flow down the tail. While the electromagnetic energy rate controls the near-earth magnetospheric activity, the kinetic energy rate should dominate the dynamics of the distant magnetotail.

  18. Magnetosphere imager science definition team interim report

    Science.gov (United States)

    Armstrong, T. P.; Johnson, C. L.

    1995-01-01

    For three decades, magnetospheric field and plasma measurements have been made by diverse instruments flown on spacecraft in may different orbits, widely separated in space and time, and under various solar and magnetospheric conditions. Scientists have used this information to piece together an intricate, yet incomplete view of the magnetosphere. A simultaneous global view, using various light wavelengths and energetic neutral atoms, could reveal exciting new data nd help explain complex magnetospheric processes, thus providing a clear picture of this region of space. This report documents the scientific rational for such a magnetospheric imaging mission and provides a mission concept for its implementation.

  19. Magnetosphere imager science definition team: Executive summary

    Science.gov (United States)

    Armstrong, T. P.; Gallagher, D. L.; Johnson, C. L.

    1995-01-01

    For three decades, magnetospheric field and plasma measurements have been made by diverse instruments flown on spacecraft in many different orbits, widely separated in space and time, and under various solar and magnetospheric conditions. Scientists have used this information to piece together an intricate, yet incomplete view of the magnetosphere. A simultaneous global view, using various light wavelengths and energetic neutral atoms, could reveal exciting new data and help explain complex magnetospheric processes, thus providing a clear picture of this region of space. This report summarizes the scientific rationale for such a magnetospheric imaging mission and outlines a mission concept for its implementation.

  20. Crafoord Symposium on Magnetospheric Physics : Achievements and Prospects

    CERN Document Server

    Fälthammar, C-G

    1990-01-01

    This book contains the proceedings of the 1989 Crafoord Symposium organized by the Royal Swedish Academy of Sciences. The scientific field for the Crafoord Prize of 1989 was decided in 1988 by the Academy to be Magnetospheric Physics. On September 27,1989 the Academy awarded the 1989 Crafoord Prize to Professor J. A. Van Allen, Iowa City, USA "for his pioneer work in space research, in particular for the discovery of the high energy charged particles that are trapped in the Earth's magnetic field and form the radiation belts -often called the Van Allen belts - around the Earth". The subject for the Crafoord Symposium, which was held on September 28-29 at the Royal Swedish Academy of Sciences in Stockholm, was Magnetospheric Physics, Achievements and Prospects. Some seventy of the world's leading scientists in magnetospheric physics (see list of participants) were invited to the Symposium. The program contained only invited papers. After the ?resentation of the Crafoord Prize Laureate, Prof. J . A. Van Allen, ...

  1. Quantitative magnetospheric models derived from spacecraft magnetometer data

    Science.gov (United States)

    Mead, G. D.; Fairfield, D. H.

    1973-01-01

    Quantitative models of the external magnetospheric field were derived by making least-squares fits to magnetic field measurements from four IMP satellites. The data were fit to a power series expansion in the solar magnetic coordinates and the solar wind-dipole tilt angle, and thus the models contain the effects of seasonal north-south asymmetries. The expansions are divergence-free, but unlike the usual scalar potential expansions, the models contain a nonzero curl representing currents distributed within the magnetosphere. Characteristics of four models are presented, representing different degrees of magnetic disturbance as determined by the range of Kp values. The latitude at the earth separating open polar cap field lines from field lines closing on the dayside is about 5 deg lower than that determined by previous theoretically-derived models. At times of high Kp, additional high latitude field lines are drawn back into the tail.

  2. Solar wind and its interaction with the magnetosphere - Measured parameters

    Energy Technology Data Exchange (ETDEWEB)

    Schwenn, R.

    1981-01-01

    The sun and the solar wind are considered in terms of the 'ballerina' model first proposed by Alfven (1977), taking into account high speed streams, the slow solar wind, stream-stream interactions, the relation of streams and magnetic structure, and transients caused by solar activity. The main features of the solar wind behavior are illustrated with the aid of data, covering one complete solar rotation in 1974/1975, which were obtained with instruments aboard the Helios-1 solar probe. It is pointed out that the solar wind acts like a huge buffer pushing onto the earth's magnetosphere with a highly variable pressure. Of the energy in the highly variable solar wind reservoir only a tiny fraction is absorbed by the magnetosphere in an obviously very nonstationary way.

  3. Solar wind and its interaction with the magnetosphere - Measured parameters

    Science.gov (United States)

    Schwenn, R.

    The sun and the solar wind are considered in terms of the 'ballerina' model first proposed by Alfven (1977), taking into account high speed streams, the slow solar wind, stream-stream interactions, the relation of streams and magnetic structure, and transients caused by solar activity. The main features of the solar wind behavior are illustrated with the aid of data, covering one complete solar rotation in 1974/1975, which were obtained with instruments aboard the Helios-1 solar probe. It is pointed out that the solar wind acts like a huge buffer pushing onto the earth's magnetosphere with a highly variable pressure. Of the energy in the highly variable solar wind reservoir only a tiny fraction is absorbed by the magnetosphere in an obviously very nonstationary way.

  4. Magnetospheric Multiscale Mission Attitude Dynamics: Observations from Flight Data

    Science.gov (United States)

    Williams, Trevor; Shulman, Seth; Sedlak, Joseph E.; Ottenstein, Neil; Lounsbury, Brian

    2016-01-01

    The NASA Magnetospheric Multiscale mission, launched on Mar. 12, 2015, is flying four spinning spacecraft in highly elliptical orbits to study the magnetosphere of the Earth. Extensive attitude data is being collected, including spin rate, spin axis orientation, and nutation rate. The paper will discuss the various environmental disturbance torques that act on the spacecraft, and will describe the observed results of these torques. In addition, a slow decay in spin rate has been observed for all four spacecraft in the extended periods between maneuvers. It is shown that this despin is consistent with the effects of an additional disturbance mechanism, namely that produced by the Active Spacecraft Potential Control devices. Finally, attitude dynamics data is used to analyze a micrometeoroid/orbital debris impact event with MMS4 that occurred on Feb. 2, 2016.

  5. The effects of stellar winds on the magnetospheres and potential habitability of exoplanets

    CERN Document Server

    See, Victor; Vidotto, Aline A; Petit, Pascal; Marsden, Stephen C; Jeffers, Sandra V; Nascimento, José Dias do

    2014-01-01

    Context: The principle definition of habitability for exoplanets is whether they can sustain liquid water on their surfaces, i.e. that they orbit within the habitable zone. However, the planet's magnetosphere should also be considered, since without it, an exoplanet's atmosphere may be eroded away by stellar winds. Aims: The aim of this paper is to investigate magnetospheric protection of a planet from the effects of stellar winds from solar-mass stars. Methods: We study hypothetical Earth-like exoplanets orbiting in the host star's habitable zone for a sample of 124 solar-mass stars. These are targets that have been observed by the Bcool collaboration. Using two wind models, we calculate the magnetospheric extent of each exoplanet. These wind models are computationally inexpensive and allow the community to quickly estimate the magnetospheric size of magnetised Earth-analogues orbiting cool stars. Results: Most of the simulated planets in our sample can maintain a magnetosphere of ~5 Earth radii or larger. T...

  6. The IMPEx data model - representation of planetary magnetospheric environment with the paraboloid model

    Science.gov (United States)

    Kalegaev, Vladimir; Kallio, Esa; Belenkaya, Elena; Alexeev, Igor; Ronan Modolo, M.; Khodachenko, Maxim; Tarek Al-Ubaidi, Di.; Mukhametdinova, Ludmila; Genot, Vincent

    Data from different sources (satellite measurements, simulation data bases and online services) are accumulated inside a digital framework developed within the FP7 project IMPEx. Paraboloid model of the planetary magnetospheres (PMM) is a part of this infrastructure. A generalized paraboloid model was developed to represent correctly the electrodynamics processes in the magnetospheres of some magnetized planets: Earth, Saturn, Jupiter and Mercury. This model is intended to calculate the magnetic field generated by a variety of current systems located on the boundaries and within the boundaries of the planetary magnetosphere under a wide range of environmental conditions, quiet and disturbed, affected by Solar activity such as Solar Flares and related phenomena. A set of Web-services to provide an access to PMM calculations and to enable the modeling data processing under SOAP protocol have been created. These will be implemented for easy data exchange within IMPEx infrastructure. Interactive models of the Earth's, Kronian and Mercury's magnetospheres, which take into account specific features of the modeled objects have been realized at Space Monitoring Data Center of SINP MSU (http://smdc.sinp.msu.ru/). The real-time model of the Earth's magnetosphere is currently working at SINP MSU Space Weather Web-site (http://swx.sinp.msu.ru/?lang=en).

  7. Plasma sources of solar system magnetospheres

    CERN Document Server

    Blanc, Michel; Chappell, Charles; Krupp, Norbert

    2016-01-01

    This volume reviews what we know of the corresponding plasma source for each intrinsically magnetized planet. Plasma sources fall essentially in three categories: the solar wind, the ionosphere (both prevalent on Earth), and the satellite-related sources. Throughout the text, the case of each planet is described, including the characteristics, chemical composition and intensity of each source. The authors also describe how the plasma generated at the source regions is transported to populate the magnetosphere, and how it is later lost. To summarize, the dominant sources are found to be the solar wind and sputtered surface ions at Mercury, the solar wind and ionosphere at Earth (the relative importance of the two being discussed in a specific introductory chapter), Io at Jupiter and – a big surprise of the Cassini findings – Enceladus at Saturn. The situation for Uranus and Neptune, which were investigated by only one fly-by each, is still open and requires further studies and exploration. In the final cha...

  8. Review of pulse impacts on the magnetospheric oscillations

    Science.gov (United States)

    Guglielmi, Anatol; Potapov, Alexander; Dovbnya, Boris; Zotov, Oleg

    2015-12-01

    Response of magnetospheric oscillatory systems in the ultra-low-frequency (ULF) range on electromagnetic, mechanical, thermal, and chemical impulse action are overviewed and selectively analyzed. Impulses can occur both inside the magnetosphere (e.g. explosion in the geomagnetic tail, impulsive injection of energetic particles) and outside (e.g. solar flare, interplanetary shock wave, thunderstorm discharge, earthquake, volcanic eruption etc.). We suggest systematics of impulses which is based on geophysics and space physics data and is closely related to the theory of ULF oscillations. The systematics is of cognitive and practical importance, and it allows us to interpret a rich variety of responses of the magnetosphere to impulses of the terrestrial and space origins. The classification principle is selected according to which an impulse type is determined from two criteria such as impulse origin location and character of impulse action on one or another oscillatory system of the magnetosphere. The primary conditions for completeness and validity of division are fulfilled because all possible terms of putting impulses to classes, types and forms are specified, and the terms do not overlap. The classification and introduced nomenclature are helpful because they make possible to systematize common properties and specific features of types and forms of impulses. This is especially important with regard to reaction of the Earth's plasma sheaths to impulses generated during an earthquake preparation as well as under experimental study of dynamic processes in the near-Earth space. The examples of response of ULF oscillations to impulsive actions are shown. The particular focus is given to review of studies which still are not mentioned in reviews and monographies.

  9. Review of pulse impacts on the magnetospheric oscillations

    Science.gov (United States)

    Guglielmi, Anatol; Potapov, Alexander; Dovbnya, Boris; Zotov, Oleg

    2015-12-01

    Response of magnetospheric oscillatory systems in the ultra-low-frequency (ULF) range on electromagnetic, mechanical, thermal, and chemical impulse action are overviewed and selectively analyzed. Impulses can occur both inside the magnetosphere (e.g. explosion in the geomagnetic tail, impulsive injection of energetic particles) and outside (e.g. solar flare, interplanetary shock wave, thunderstorm discharge, earthquake, volcanic eruption etc.). We suggest systematics of impulses which is based on geophysics and space physics data and is closely related to the theory of ULF oscillations. The systematics is of cognitive and practical importance, and it allows us to interpret a rich variety of responses of the magnetosphere to impulses of the terrestrial and space origins. The classification principle is selected according to which an impulse type is determined from two criteria such as impulse origin location and character of impulse action on one or another oscillatory system of the magnetosphere. The primary conditions for completeness and validity of division are fulfilled because all possible terms of putting impulses to classes, types and forms are specified, and the terms do not overlap. The classification and introduced nomenclature are helpful because they make possible to systematize common properties and specific features of types and forms of impulses. This is especially important with regard to reaction of the Earth's plasma sheaths to impulses generated during an earthquake preparation as well as under experimental study of dynamic processes in the near-Earth space. The examples of response of ULF oscillations to impulsive actions are shown. The particular focus is given to review of studies which still are not mentioned in reviews and monographies.

  10. Radio emission in Mercury magnetosphere

    Science.gov (United States)

    Varela, J.; Reville, V.; Brun, A. S.; Pantellini, F.; Zarka, P.

    2016-10-01

    Context. Active stars possess magnetized wind that has a direct impact on planets that can lead to radio emission. Mercury is a good test case to study the effect of the solar wind and interplanetary magnetic field (IMF) on radio emission driven in the planet magnetosphere. Such studies could be used as proxies to characterize the magnetic field topology and intensity of exoplanets. Aims: The aim of this study is to quantify the radio emission in the Hermean magnetosphere. Methods: We use the magnetohydrodynamic code PLUTO in spherical coordinates with an axisymmetric multipolar expansion for the Hermean magnetic field, to analyze the effect of the IMF orientation and intensity, as well as the hydrodynamic parameters of the solar wind (velocity, density and temperature), on the net power dissipated on the Hermean day and night side. We apply the formalism derived by Zarka et al. (2001, Astrophys. Space Sci., 277, 293), Zarka (2007, Planet. Space Sci., 55, 598) to infer the radio emission level from the net dissipated power. We perform a set of simulations with different hydrodynamic parameters of the solar wind, IMF orientations and intensities, that allow us to calculate the dissipated power distribution and infer the existence of radio emission hot spots on the planet day side, and to calculate the integrated radio emission of the Hermean magnetosphere. Results: The obtained radio emission distribution of dissipated power is determined by the IMF orientation (associated with the reconnection regions in the magnetosphere), although the radio emission strength is dependent on the IMF intensity and solar wind hydro parameters. The calculated total radio emission level is in agreement with the one estimated in Zarka et al. (2001, Astrophys. Space Sci., 277, 293) , between 5 × 105 and 2 × 106 W.

  11. Magnetohydrodynamic Modeling of the Jovian Magnetosphere

    Science.gov (United States)

    Walker, Raymond

    2005-01-01

    Under this grant we have undertaken a series of magnetohydrodynamic (MHD) simulation and data analysis studies to help better understand the configuration and dynamics of Jupiter's magnetosphere. We approached our studies of Jupiter's magnetosphere in two ways. First we carried out a number of studies using our existing MHD code. We carried out simulation studies of Jupiter s magnetospheric boundaries and their dependence on solar wind parameters, we studied the current systems which give the Jovian magnetosphere its unique configuration and we modeled the dynamics of Jupiter s magnetosphere following a northward turning of the interplanetary magnetic field (IMF). Second we worked to develop a new simulation code for studies of outer planet magnetospheres.

  12. Ensemble downscaling in coupled solar wind-magnetosphere modeling for space weather forecasting.

    Science.gov (United States)

    Owens, M J; Horbury, T S; Wicks, R T; McGregor, S L; Savani, N P; Xiong, M

    2014-06-01

    Advanced forecasting of space weather requires simulation of the whole Sun-to-Earth system, which necessitates driving magnetospheric models with the outputs from solar wind models. This presents a fundamental difficulty, as the magnetosphere is sensitive to both large-scale solar wind structures, which can be captured by solar wind models, and small-scale solar wind "noise," which is far below typical solar wind model resolution and results primarily from stochastic processes. Following similar approaches in terrestrial climate modeling, we propose statistical "downscaling" of solar wind model results prior to their use as input to a magnetospheric model. As magnetospheric response can be highly nonlinear, this is preferable to downscaling the results of magnetospheric modeling. To demonstrate the benefit of this approach, we first approximate solar wind model output by smoothing solar wind observations with an 8 h filter, then add small-scale structure back in through the addition of random noise with the observed spectral characteristics. Here we use a very simple parameterization of noise based upon the observed probability distribution functions of solar wind parameters, but more sophisticated methods will be developed in the future. An ensemble of results from the simple downscaling scheme are tested using a model-independent method and shown to add value to the magnetospheric forecast, both improving the best estimate and quantifying the uncertainty. We suggest a number of features desirable in an operational solar wind downscaling scheme.

  13. Magnetospherically driven optical and radio aurorae at the end of the stellar main sequence.

    Science.gov (United States)

    Hallinan, G; Littlefair, S P; Cotter, G; Bourke, S; Harding, L K; Pineda, J S; Butler, R P; Golden, A; Basri, G; Doyle, J G; Kao, M M; Berdyugina, S V; Kuznetsov, A; Rupen, M P; Antonova, A

    2015-07-30

    Aurorae are detected from all the magnetized planets in our Solar System, including Earth. They are powered by magnetospheric current systems that lead to the precipitation of energetic electrons into the high-latitude regions of the upper atmosphere. In the case of the gas-giant planets, these aurorae include highly polarized radio emission at kilohertz and megahertz frequencies produced by the precipitating electrons, as well as continuum and line emission in the infrared, optical, ultraviolet and X-ray parts of the spectrum, associated with the collisional excitation and heating of the hydrogen-dominated atmosphere. Here we report simultaneous radio and optical spectroscopic observations of an object at the end of the stellar main sequence, located right at the boundary between stars and brown dwarfs, from which we have detected radio and optical auroral emissions both powered by magnetospheric currents. Whereas the magnetic activity of stars like our Sun is powered by processes that occur in their lower atmospheres, these aurorae are powered by processes originating much further out in the magnetosphere of the dwarf star that couple energy into the lower atmosphere. The dissipated power is at least four orders of magnitude larger than what is produced in the Jovian magnetosphere, revealing aurorae to be a potentially ubiquitous signature of large-scale magnetospheres that can scale to luminosities far greater than those observed in our Solar System. These magnetospheric current systems may also play a part in powering some of the weather phenomena reported on brown dwarfs.

  14. Dynamic Boundaries of Event Horizon Magnetospheres

    OpenAIRE

    Punsly, Brian

    2007-01-01

    This Letter analyzes 3-dimensional simulations of Kerr black hole magnetospheres that obey the general relativistic equations of perfect magnetohydrodynamics (MHD). Particular emphasis is on the event horizon magnetosphere (EHM) which is defined as the the large scale poloidal magnetic flux that threads the event horizon of a black hole (This is distinct from the poloidal magnetic flux that threads the equatorial plane of the ergosphere, which forms the ergospheric disk magnetosphere). Standa...

  15. Using global magnetospheric models for simulation and interpretation of Swarm external field measurements

    DEFF Research Database (Denmark)

    Moretto, T.; Vennerstrøm, Susanne; Olsen, Nils

    2006-01-01

    We have used a global model of the solar wind magnetosphere interaction to model the high latitude part of the external contributions to the geomagnetic field near the Earth. The model also provides corresponding values for the electric field. Geomagnetic quiet conditions were modeled to provide...

  16. DYNAMICS OF STRONGLY TWISTED RELATIVISTIC MAGNETOSPHERES

    Energy Technology Data Exchange (ETDEWEB)

    Parfrey, Kyle [Astronomy Department, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Beloborodov, Andrei M.; Hui, Lam, E-mail: parfrey@astro.princeton.edu [Physics Department and Columbia Astrophysics Laboratory, Columbia University, 538 West 120th Street, New York, NY 10027 (United States)

    2013-09-10

    Magnetar magnetospheres are believed to be strongly twisted due to shearing of the stellar crust by internal magnetic stresses. We present time-dependent axisymmetric simulations showing in detail the evolution of relativistic force-free magnetospheres subjected to slow twisting through large angles. When the twist amplitude is small, the magnetosphere moves quasi-statically through a sequence of equilibria of increasing free energy. At some twist amplitude the magnetosphere becomes tearing-mode unstable to forming a resistive current sheet, initiating large-scale magnetic reconnection in which a significant fraction of the magnetic free energy can be dissipated. This ''critical'' twist angle is insensitive to the resistive length scale. Rapid shearing temporarily stabilizes the magnetosphere beyond the critical angle, allowing the magnetosphere of a rapidly differentially rotating star to store and dissipate more free energy. In addition to these effects, shearing the surface of a rotating star increases the spindown torque applied to the star. If shearing is much slower than rotation, the resulting spikes in spindown rate can occur on timescales anywhere from the long twisting timescale to the stellar spin period or shorter, depending both on the stellar shear distribution and the existing distribution of magnetospheric twists. A model in which energy is stored in the magnetosphere and released by a magnetospheric instability therefore predicts large changes in the measured spindown rate before soft gamma repeater giant flares.

  17. Minute-scale period oscillations of the magnetosphere

    Science.gov (United States)

    Pécseli, H. L.; Sato, H.; Børve, S.; Trulsen, J. K.

    2012-04-01

    Oscillations with periods on the order of 5-10 min have been observed by instrumented spacecrafts in the Earth's magnetosphere. These oscillations often follow sudden impacts related to coronal mass ejections. It is demonstrated that a simple model is capable of explaining the basic properties of these oscillations and give scaling laws for their basic characteristics in terms of the basic parameters of the problem. The period of the oscillations and their anharmonic nature, in particular, are accounted for. The model has no free adjustable numerical parameters. We use measurable quantities as inputs (such as Solar wind momentum density), and our results can be seen as an effort to predict some dynamic properties of magnetospheres on the basis of measurable steady state characteristics. A simple test of the model is found by comparing its prediction of the Earth-Magnetopause distance with observed values. The general results agree with observations. The analysis is supported by numerical simulations solving the Magneto-Hydro-Dynamic (MHD) equations in two spatial dimensions, where we let a solar wind interact with a magnetic dipole representing a magnetized Earth. Two tilt-angles of the magnetic dipole axis were considered. We observed the formation of a magnetosheath, with the magnetopause at a distance corresponding well to the analytical results. Sudden pulses in the model solar wind set the model magnetosphere into damped oscillatory motions and quantitatively good agreement with the analytical results is found. The models seem to be robust, and give good qualitative agreement with the numerical simulations for a range of parameters.

  18. Global fully kinetic models of planetary magnetospheres with iPic3D

    Science.gov (United States)

    Gonzalez, D.; Sanna, L.; Amaya, J.; Zitz, A.; Lembege, B.; Markidis, S.; Schriver, D.; Walker, R. J.; Berchem, J.; Peng, I. B.; Travnicek, P. M.; Lapenta, G.

    2016-12-01

    We report on the latest developments of our approach to model planetary magnetospheres, mini magnetospheres and the Earth's magnetosphere with the fully kinetic, electromagnetic particle in cell code iPic3D. The code treats electrons and multiple species of ions as full kinetic particles. We review: 1) Why a fully kinetic model and in particular why kinetic electrons are needed for capturing some of the most important aspects of the physics processes of planetary magnetospheres. 2) Why the energy conserving implicit method (ECIM) in its newest implementation [1] is the right approach to reach this goal. We consider the different electron scales and study how the new IECIM can be tuned to resolve only the electron scales of interest while averaging over the unresolved scales preserving their contribution to the evolution. 3) How with modern computing planetary magnetospheres, mini magnetosphere and eventually Earth's magnetosphere can be modeled with fully kinetic electrons. The path from petascale to exascale for iPiC3D is outlined based on the DEEP-ER project [2], using dynamic allocation of different processor architectures (Xeon and Xeon Phi) and innovative I/O technologies.Specifically results from models of Mercury are presented and compared with MESSENGER observations and with previous hybrid (fluid electrons and kinetic ions) simulations. The plasma convection around the planets includes the development of hydrodynamic instabilities at the flanks, the presence of the collisionless shocks, the magnetosheath, the magnetopause, reconnection zones, the formation of the plasma sheet and the magnetotail, and the variation of ion/electron plasma flows when crossing these frontiers. Given the full kinetic nature of our approach we focus on detailed particle dynamics and distribution at locations that can be used for comparison with satellite data. [1] Lapenta, G. (2016). Exactly Energy Conserving Implicit Moment Particle in Cell Formulation. arXiv preprint ar

  19. International Sun-Earth Explorer (ISEE)

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    Series of three US satellites designed to study the solar wind and its interaction with the Earth's magnetosphere. ISEE-1 and 2 were placed into highly elliptical Earth orbits. ISEE-3 was placed in a halo orbit at the L1 Lagrangian point between the Sun and Earth. It gave advance warning of solar storms heading towards Earth. (See also INTERNATIONAL COMETARY EXPLORER and EXPLORER.)...

  20. Saturnian magnetospheric dynamics: Elucidation of a camshaft model

    Science.gov (United States)

    Southwood, D. J.; Kivelson, M. G.

    2007-12-01

    Periodic modulation of magnetospheric phenomena at Earth and Jupiter results principally from the tilt of the dipole axis relative to the rotation axis. Saturn's nearly aligned dipole moment is tilted by less than 0.5° from the spin axis, yet the power of radio-frequency emissions, the orientation of the magnetic field, and many properties of the magnetospheric plasma vary periodically at the approximate rate of Saturn's rotation. Here we examine properties of the periodic magnetic signal detected in the magnetospheric regions inside ~12-15 R S . We show that it is associated with a rotating nonaxisymmetric system of field-aligned currents flowing on magnetic shells bounding the region where the signals are seen. Magnetohydrodynamic ideas suggest that these currents would drive rotating plasma flow patterns in the northern and southern ionospheres, with the flows oppositely directed in the two hemispheres. On magnetic shells beyond the sheets of field-aligned current, the magnetic perturbations generate an effective rotating equatorial dipole moment that when added to the planetary dipole moment, produces a dipole moment tilted relative to the spin axis at an angle of order 12-15°. The overt source of the north-south asymmetric ionospheric circulation could link to different ionospheric conductances that result from nonuniform solar illumination. Other possible sources are discussed but, although we can elucidate much, the origin of the cam signal (as well as other phenomena such as the Saturn kilometric radio emission with close to the same period) remains enigmatic.

  1. Saturn's Radio Emissions and their Relation to Magnetospheric Dynamics

    Science.gov (United States)

    Jackman, C. M.

    With the arrival of the Cassini spacecraft at Saturn in July 2004, there have been quasi-continuous observations of Saturn Kilometric Radiation (SKR) emissions. In this paper we review the response of these emissions to dynamics in Saturn's magnetosphere, driven by factors internal and external to the system. We begin by reviewing solar wind data upstream of Saturn and discuss the link between solar wind compressions and dynamics in Saturn's magnetosphere, evidenced by intensifications and occasional phase changes in the SKR emission. We then review the link between magnetotail reconnection and planetary radio emissions. We begin in the well-sampled magnetotail of Earth and then move to Saturn where exploration of the nightside magnetosphere has revealed evidence of plasmoid-like magnetic structures and other phenomena indicative of the kronian equivalent of terrestrial substorms. In general, there is a good correlation between the timing of reconnection events and enhancements in the SKR emission, coupled with extension of the emission to lower frequencies. We interpret this as growth of the radio source region to higher altitudes along the field lines, stimulated by increased precipitation of energetic electrons into the auroral zones following reconnection. We also comment on the observation that the majority of reconnection events occur at SKR phases where the SKR power would be expected to be rising with time, indicating that reconnection is most likely to occur at a preferred phase. We conclude with a summary of the current knowledge of the link between Saturn's magnetospheric dynamics and SKR emissions, and list a number of open questions to be addressed in the future.

  2. Navigation Operations for the Magnetospheric Multiscale Mission

    Science.gov (United States)

    Long, Anne; Farahmand, Mitra; Carpenter, Russell

    2015-01-01

    The Magnetospheric Multiscale (MMS) mission employs four identical spinning spacecraft flying in highly elliptical Earth orbits. These spacecraft will fly in a series of tetrahedral formations with separations of less than 10 km. MMS navigation operations use onboard navigation to satisfy the mission definitive orbit and time determination requirements and in addition to minimize operations cost and complexity. The onboard navigation subsystem consists of the Navigator GPS receiver with Goddard Enhanced Onboard Navigation System (GEONS) software, and an Ultra-Stable Oscillator. The four MMS spacecraft are operated from a single Mission Operations Center, which includes a Flight Dynamics Operations Area (FDOA) that supports MMS navigation operations, as well as maneuver planning, conjunction assessment and attitude ground operations. The System Manager component of the FDOA automates routine operations processes. The GEONS Ground Support System component of the FDOA provides the tools needed to support MMS navigation operations. This paper provides an overview of the MMS mission and associated navigation requirements and constraints and discusses MMS navigation operations and the associated MMS ground system components built to support navigation-related operations.

  3. Lunar biological effects and the magnetosphere.

    Science.gov (United States)

    Bevington, Michael

    2015-12-01

    The debate about how far the Moon causes biological effects has continued for two millennia. Pliny the Elder argued for lunar power "penetrating all things", including plants, fish, animals and humans. He also linked the Moon with tides, confirmed mathematically by Newton. A review of modern studies of biological effects, especially from plants and animals, confirms the pervasive nature of this lunar force. However calculations from physics and other arguments refute the supposed mechanisms of gravity and light. Recent space exploration allows a new approach with evidence of electromagnetic fields associated with the Earth's magnetotail at full moon during the night, and similar, but more limited, effects from the Moon's wake on the magnetosphere at new moon during the day. The disturbance of the magnetotail is perhaps shown by measurements of electric fields of up to 16V/m compared with the usual effects on some sensitive organisms. Similar intensities found in sferics, geomagnetic storms, aurora disturbance, sensations of a 'presence' and pre-seismic electromagnetic radiation are known to affect animals and 10-20% of the human population. There is now evidence for mechanisms such as calcium flux, melatonin disruption, magnetite and cryptochromes. Both environmental and receptor variations explain confounding factors and inconsistencies in the evidence. Electromagnetic effects might also account for some evolutionary changes. Further research on lunar biological effects, such as acute myocardial infarction, could help the development of strategies to reduce adverse effects for people sensitive to geomagnetic disturbance. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  4. Magnetospheric multiprobes: Investigations and instrumentation

    Science.gov (United States)

    Burch, J. L.; Chappell, C. R.; Fields, S. A.; Falthammar, C. G.; Winningham, J. D.; Hanson, W. B.; Heelis, R. A.; Heikkila, W. J.; Sugira, M.; Farthing, W. H.

    1980-01-01

    The multiprobe scientific objectives are to: (1) determine the spatial structure of plasma phenomena such as the aurora, convection reversals, and ion troughs; (2) separate spatial and temporal variations in these phenomena; (3) determine field aligned current densities; (4) perform multiple point analysis of particle beams, wave fields, and plasma clouds that are injected into the ionosphere and magnetosphere by Spacelab active experiment facilities. Trade studies described include: instrument accommodations, power, attitude determination, electric field antennas, storage and ejection, thermal control, tracking communications, command and data management, payload and mission specialist support, functional objectives, and orbital analysis.

  5. Current Flows in Pulsar Magnetospheres

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The global structure of .current flows in pulsar magnetosphere is investigated, with rough calculations of the circuit elements. It is emphasized that the potential of the critical field lines (the field lines that intersect the null surface at the light cylinder radius) should be the same as that of interstellar medium, and that pulsars whose rotation axes and magnetic dipole axes are parallel should be positively charged, in order to close the pulsar's current flows. The statistical relation between the radio luminosity and pulsar's electric charge (or the spindown power) may hint that the millisecond pulsars could be low-mass bare strange stars.

  6. Understanding pulsar magnetospheres with the SKA

    CERN Document Server

    Karastergiou, A; Andersson, N; Breton, R; Brook, P; Gwinn, C; Lewandowska, N; Keane, E; Kramer, M; Macquart, J -P; Serylak, M; Shannon, R; Stappers, B; van Leeuwen, J; Verbiest, J P W; Weltevrede, P; Wright, G

    2015-01-01

    The SKA will discover tens of thousands of pulsars and provide unprecedented data quality on these, as well as the currently known population, due to its unrivalled sensitivity. Here, we outline the state of the art of our understanding of magnetospheric radio emission from pulsars and how we will use the SKA to solve the open problems in pulsar magnetospheric physics.

  7. The Community-based Whole Magnetosphere Model

    Science.gov (United States)

    2011-11-15

    Tribulations and Exultations in Coupling Models of the Magnetosphere with Ionosphere-Thermosphere Models, Plane- tary Aeronomy ISSI Meeting, Bern...Exultations in Coupling Models of the Magnetosphere CWMM-19 Ridley CWMM Final Report with Ionosphere-Thermosphere Models, Plane- tary Aeronomy ISSI

  8. Magnetospheric ULF waves driven by external sources

    CERN Document Server

    Agapitov, Oleksiy

    2015-01-01

    The multi-spacecraft missions (Cluster and THEMIS) observations allowed to collect large data base for Ultra Low Frequency (ULF) waves properties, their localization, and sources. Mainly here we focused on these recent results. Studying of the source and characteristics of ULF waves can help in the understanding of the interaction and energy transport from solar wind to the magnetosphere. Here we present peculiarities of ULF waves generated by different solar wind phenomenon: surface magnetopause instability, magnetosphere cavity modes and solar wind dynamic pressure sudden impulses (SI) penetration into the magnetosphere. Permanent observations of ULF waves involve existence of the permanent source and, as the previous studies showed, the contributions to Pc4-Pc5 ULF wave power from the external sources are larger than the contribution from internal magnetosphere sources. The Kelvin-Helmholtz instability (KHI) can generate on the magnetosphere flanks classical ULF resonant waves with spatially localized ampl...

  9. Radio emission in Mercury magnetosphere

    CERN Document Server

    Varela, J; Brun, A S; Pantellini, F; Zarka, P

    2016-01-01

    Context: Active stars possess magnetized wind that has a direct impact on planets that can lead to radio emission. Mercury is a good test case to study the effect of the solar wind and interplanetary magnetic field on radio emission driven in the planet magnetosphere. Such studies could be used as proxies to characterize the magnetic field topology and intensity of exoplanets. Aims: The aim of this study is to quantify the radio emission in the Hermean magnetosphere. Methods: We use the MHD code PLUTO in spherical coordinates with an axisymmetric multipolar expansion for the Hermean magnetic field, to analyze the effect of the interplanetary magnetic field (IMF) orientation and intensity, as well as the hydrodynamic parameters of the solar wind (velocity, density and temperature), on the net power dissipated on the Hermean day and night side. We apply the formalism derived by Zarka [2001, 2007] to infer the radio emission level from the net dissipated power. We perform a set of simulations with different hydr...

  10. Inner Magnetosphere Simulations: Exploring Magnetosonic Wave Generation Conditions

    Science.gov (United States)

    Zaharia, S. G.; Jordanova, V. K.; MacDonald, E.; Thomsen, M. F.

    2012-12-01

    We investigate the conditions for magnetosonic wave generation in the near-Earth magnetosphere by performing numerical simulations with our newly improved self-consistent model, RAM-SCB. The magnetosonic (ion Bernstein) instability, a potential electron acceleration mechanism in the outer radiation belt, is driven by a positive slope in the ion distribution function perpendicular to the magnetic field, a so-called "velocity ring" distribution at energies above 1 keV. The formation of such distributions is dependent on the interplay of magnetic and electric drifts, as well as ring current losses, and therefore its study requires a realistic treatment of both plasma and field dynamics. The RAM-SCB model represents a 2-way coupling of the kinetic ring current-atmosphere interactions model (RAM) with a 3D plasma equilibrium code. In RAM-SCB the magnetic field is computed in force balance with the RAM anisotropic pressures and then returned to RAM to guide the particle dynamics. RAM-SCB thus properly treats both the kinetic drift physics crucial in the inner magnetosphere and the self-consistent interaction between plasma and magnetic field (required due to the strong field depressions during storms, depressions that strongly affect particle drifts). In order to provide output at geosynchronous locations, recently the RAM-SCB boundary has been expanded to 9 RE from Earth, with plasma pressure and magnetic field boundary conditions prescribed there from empirical models. This presentation will analyze, using event simulations with the improved model and comparisons with LANL MPA geosynchronous observations, the occurrence and location of magnetosonic unstable regions in the inner magnetosphere and their dependence on the following factors: 1). geomagnetic activity level (including quiet time, storm main phase and recovery); 2). magnetic field self-consistency (stretched vs. dipole fields). We will also discuss the physical mechanism for the occurrence of the velocity

  11. Magnetic latitude dependence of oxygen charge states in the global magnetosphere: Insights into solar wind-originating ion injection

    Science.gov (United States)

    Allen, R. C.; Livi, S. A.; Vines, S. K.; Goldstein, J.

    2016-10-01

    Understanding the sources and subsequent evolution of plasma in a magnetosphere holds intrinsic importance for magnetospheric dynamics. Previous studies have investigated the balance of ionospheric-originating heavy ions (low charge state) from those of solar wind origin (high charge state) in the magnetosphere of Earth. These studies have suggested a variety of entry mechanisms for solar wind ions to penetrate into the magnetosphere. Following from recently published distributions for oxygen charge states observed by the Polar spacecraft, this paper investigates oxygen charge state flux distributions versus L shell and magnetic latitude. By showing these distributions in this frame, and binning by various proxies for magnetospheric dynamics (Dst, AE, VSW∗BZ, Pdyn), insight has been gained into the underlying physics at play for oxygen injection. Ionospheric-originating oxygen is observed to depend predominantly on Dst, whereas solar wind-originating oxygen is observed to have a strong dependence on solar wind dynamic pressure (Pdyn) at the flanks and on VSW∗BZ at the dayside. This suggests that both Kelvin-Helmholtz instabilities and reconnection play major roles in solar wind ion penetration into a magnetosphere. Additionally, the near-Earth magnetotail reconnection site does not seem to be a major injection site of solar wind-originating plasma in the 1 to 200 keV/e energy range.

  12. The Scientific Foundations of Forecasting Magnetospheric Space Weather

    Science.gov (United States)

    Eastwood, J. P.; Nakamura, R.; Turc, L.; Mejnertsen, L.; Hesse, M.

    2017-08-01

    The magnetosphere is the lens through which solar space weather phenomena are focused and directed towards the Earth. In particular, the non-linear interaction of the solar wind with the Earth's magnetic field leads to the formation of highly inhomogenous electrical currents in the ionosphere which can ultimately result in damage to and problems with the operation of power distribution networks. Since electric power is the fundamental cornerstone of modern life, the interruption of power is the primary pathway by which space weather has impact on human activity and technology. Consequently, in the context of space weather, it is the ability to predict geomagnetic activity that is of key importance. This is usually stated in terms of geomagnetic storms, but we argue that in fact it is the substorm phenomenon which contains the crucial physics, and therefore prediction of substorm occurrence, severity and duration, either within the context of a longer-lasting geomagnetic storm, but potentially also as an isolated event, is of critical importance. Here we review the physics of the magnetosphere in the frame of space weather forecasting, focusing on recent results, current understanding, and an assessment of probable future developments.

  13. Saturation of the Electric Field Transmitted to the Magnetosphere

    Science.gov (United States)

    Lyatsky, Wladislaw; Khazanov, George V.; Slavin, James A.

    2010-01-01

    We reexamined the processes leading to saturation of the electric field, transmitted into the Earth's ionosphere from the solar wind, incorporating features of the coupled system previously ignored. We took into account that the electric field is transmitted into the ionosphere through a region of open field lines, and that the ionospheric conductivity in the polar cap and auroral zone may be different. Penetration of the electric field into the magnetosphere is linked with the generation of the Alfven wave, going out from the ionosphere into the solar wind and being coupled with the field-aligned currents at the boundary of the open field limes. The electric field of the outgoing Alfven wave reduces the original electric field and provides the saturation effect in the electric field and currents during strong geomagnetic disturbances, associated with increasing ionospheric conductivity. The electric field and field-aligned currents of this Alfven wave are dependent on the ionospheric and solar wind parameters and may significantly affect the electric field and field-aligned currents, generated in the polar ionosphere. Estimating the magnitude of the saturation effect in the electric field and field-aligned currents allows us to improve the correlation between solar wind parameters and resulting disturbances in the Earth's magnetosphere.

  14. Solar Wind Driving of Magnetospheric ULF Waves: Pulsations Driven by Velocity Shear at the Magnetopause

    CERN Document Server

    Claudepierre, S G; Wiltberger, M; 10.1029/2007JA012890

    2010-01-01

    We present results from global, three-dimensional magnetohydrodynamic (MHD) simulations of the solar wind/magnetosphere interaction. These MHD simulations are used to study ultra low frequency (ULF) pulsations in the Earth's magnetosphere driven by shear instabilities at the flanks of the magnetopause. We drive the simulations with idealized, constant solar wind input parameters, ensuring that any discrete ULF pulsations generated in the simulation magnetosphere are not due to fluctuations in the solar wind. The simulations presented in this study are driven by purely southward interplanetary magnetic field (IMF) conditions, changing only the solar wind driving velocity while holding all of the other solar wind input parameters constant. We find surface waves near the dawn and dusk flank magnetopause and show that these waves are generated by the Kelvin-Helmholtz (KH) instability. We also find that two KH modes are generated near the magnetopause boundary. One mode, the magnetopause KH mode, propagates tailwa...

  15. Pitch-angle diffusion coefficients from resonant interactions with electrostatic electron cyclotron harmonic waves in planetary magnetospheres

    Directory of Open Access Journals (Sweden)

    A. K. Tripathi

    2011-02-01

    Full Text Available Pitch-angle diffusion coefficients have been calculated for resonant interaction with electrostatic electron cyclotron harmonic (ECH waves in the magnetospheres of Earth, Jupiter, Saturn, Uranus and Neptune. Calculations have been performed at two radial distances of each planet. It is found that observed wave electric field amplitudes in the magnetospheres of Earth and Jupiter are sufficient to put electrons on strong diffusion in the energy range of less than 100 eV. However, for Saturn, Uranus and Neptune, the observed ECH wave amplitude are insufficient to put electrons on strong diffusion at any radial distance.

  16. Pitch-angle diffusion coefficients from resonant interactions with electrostatic electron cyclotron harmonic waves in planetary magnetospheres

    Science.gov (United States)

    Tripathi, A. K.; Singhal, R. P.; Singh, K. P.

    2011-02-01

    Pitch-angle diffusion coefficients have been calculated for resonant interaction with electrostatic electron cyclotron harmonic (ECH) waves in the magnetospheres of Earth, Jupiter, Saturn, Uranus and Neptune. Calculations have been performed at two radial distances of each planet. It is found that observed wave electric field amplitudes in the magnetospheres of Earth and Jupiter are sufficient to put electrons on strong diffusion in the energy range of less than 100 eV. However, for Saturn, Uranus and Neptune, the observed ECH wave amplitude are insufficient to put electrons on strong diffusion at any radial distance.

  17. Quasi-Periodic Whistler Mode Emissions in Saturn's Inner Magnetosphere

    Science.gov (United States)

    Hospodarsky, George; Leisner, Jared; Cinar, Gokcin; Kurth, William; Gurnett, Donald; Santolik, Ondrej

    2016-04-01

    The Cassini Radio and Plasma Wave Science (RPWS) instrument often detects at Saturn a series of quasi-periodic (QP) whistler mode emissions that rise in frequency and repeat every few to about ten minutes. These QP emissions are detected about 5% of the time when Cassini is within ~5.5 Rs of Saturn and are primarily observed near the magnetic equator. They are usually detected in the frequency range of about 1 to 3 kHz, and appear to be related to electrons with energies of a few keV. Their spectral characteristics are very similar to the quasi-periodic whistler mode emissions detected in Earth's magnetosphere. However, it is unclear if the same type of source generation can explain the Earth and Saturn QP emissions.

  18. Ionospheric control of the magnetosphere: conductance

    Directory of Open Access Journals (Sweden)

    A. J. Ridley

    2004-01-01

    Full Text Available It is well known that the ionosphere plays a role in determining the global state of the magnetosphere. The ionosphere allows magnetospheric currents to close, thereby allowing magnetospheric convection to occur. The amount of current which can be carried through the ionosphere is mainly determined by the ionospheric conductivity. This paper starts to quantify the nonlinear relationship between the ionospheric conductivity and the global state of the magnetosphere. It is found that the steady-state magnetosphere acts neither as a current nor as a voltage generator; a uniform Hall conductance can influence the potential pattern at low latitudes, but not at high latitude; the EUV generated conductance forces the currents to close in the sunlight, while the potential is large on the nightside; the solar generated Hall conductances cause a large asymmetry between the dawn and dusk potential, which effects the pressure distribution in the magnetosphere; a uniform polar cap potential removes some of this asymmetry; the potential difference between solar minimum and maximum is ∼11%; and the auroral precipitation can be related to the local field-aligned current through an exponential function.

    Key words. Ionosphere (ionosphere-magnetosphere interactions; modelling and forecasting; polar ionosphere

  19. Observations of Magnetic Reconnection and Plasma Dynamics in Mercury's Magnetosphere

    Science.gov (United States)

    DiBraccio, Gina A.

    transferred into the system. We conclude that Mercury's magnetosphere is a dynamic environment with constant plasma and magnetic flux circulation as a result of frequent and intense magnetic reconnection. These results are directly applicable to the understanding of geomagnetic storms at Earth, when coronal mass ejections produce solar wind parameters similar to those regularly experienced by Mercury.

  20. Shrinkage of magnetosphere observed by TC-1 satellite during the high-speed solar wind stream

    Institute of Scientific and Technical Information of China (English)

    H.; RME; I.; DANDOURAS; C.; M.; CARR

    2008-01-01

    During the interval 06:14―07:30 UT on August 24, 2005, since the Earth’s magneto- pause was suddenly compressed by the persistent high-speed solar wind stream with the southward component of the interplanetary magnetic field (IMF), the magnetopause moved inward for about 3.1 RE. Meanwhile, TC-1 satellite shifted from northern plasma sheet to the northern lobe/mantle region, although it kept inward flying during the interval 06:00―07:30UT. The shift of TC-1 from the plasma sheet to the lobe/mantle is caused by the simultaneous inward displacements of the plasma sheet and near-Earth lobe/mantle region, and their inward movement velocity is larger than the inward motion velocity of TC-1. The joint inward dis-placements of the magnetopause, the lobe/mantle region and the plasma sheet indicate that the whole magnetosphere shrinks inward due to the magnetospheric compression by the high-speed solar wind stream, and the magnetospheric ions are attached to the magnetic field lines (i.e. ‘frozen’ in magnetic field) and move inward in the shrinking process of magnetosphere. The large shrinkage of magne-tosphere indicates that the near-Earth magnetotail compression caused by the strong solar wind dynamic pressure is much larger than its thickening caused by the southward component of the IMF, and the locations of magnetospheric regions with different plasmas vary remarkably with the variation of the solar wind dynamic pressure.

  1. Dynamic models for magnetospheric oscillations on the minute scale

    Science.gov (United States)

    Sato, H.; Pecseli, H.; Børve, S.; Trulsen, J.

    2012-12-01

    Sudden pulses in the model solar wind sets the Earth's magnetosphere into damped oscillatory motions. Oscillation periods on the order of 5-10 min have been observed by instrumented spacecrafts. A simple model is capable of explaining the basic properties of these oscillations and give scaling laws for their characteristics in terms of the parameters of the problem, such as the Solar wind momentum density. The period of the oscillations, their damping and anharmonic nature are accounted for.The model has no free adjustable numerical parameters and can be seen as an effort to predict some dynamic properties of the magnetosphere on the basis of measurable steady state characteristics. A simple test of the model is found by comparing its prediction of the Earth-Magnetopause distance with observed values. The results agree well with observations. The analysis is supported by numerical simulations solving the Magneto-Hydro-Dynamic (MHD) equations in two spatial dimensions, where we let a solar wind interact with a magnetic dipole representing a magnetized Earth. Two tilt-angles of the magnetic dipole axis were considered. We observe the formation of a magnetosheath, with the magnetopause at a distance corresponding well to the analytical results. The analytical model seem to be robust, and gives good qualitative agreement with the numerical simulations for a range of parameters, also concerning oscillation periods and damping times for cases where the dynamic response to perturbations are considered. The analysis allows also for predicting the magnetic field perturbations detected on Earth due to changes in the magnetosheath current. In order to improve the model we study a conformal mapping that brings the shape of the magnetosheath model closer to observations.

  2. Theory of neutron star magnetospheres

    CERN Document Server

    Curtis Michel, F

    1990-01-01

    An incomparable reference for astrophysicists studying pulsars and other kinds of neutron stars, "Theory of Neutron Star Magnetospheres" sums up two decades of astrophysical research. It provides in one volume the most important findings to date on this topic, essential to astrophysicists faced with a huge and widely scattered literature. F. Curtis Michel, who was among the first theorists to propose a neutron star model for radio pulsars, analyzes competing models of pulsars, radio emission models, winds and jets from pulsars, pulsating X-ray sources, gamma-ray burst sources, and other neutron-star driven phenomena. Although the book places primary emphasis on theoretical essentials, it also provides a considerable introduction to the observational data and its organization. Michel emphasizes the problems and uncertainties that have arisen in the research as well as the considerable progress that has been made to date.

  3. Phenomenology of magnetospheric radio emissions

    Science.gov (United States)

    Carr, T. D.; Desch, M. D.; Alexander, J. K.

    1983-01-01

    Jupiter has now been observed over 24 octaves of the radio spectrum, from about 0.01 MHz to 300,000 MHz. Its radio emissions fill the entire spectral region where interplanetary electromagnetic propagation is possible at wavelengths longer than infrared. Three distinct types of radiation are responsible for this radio spectrum. Thermal emission from the atmosphere accounts for virtually all the radiation at the high frequency end. Synchrotron emission from the trapped high-energy particle belt deep within the inner magnetosphere is the dominant spectral component from about 4000 to 40 MHz. The third class of radiation consists of several distinct components of sporadic low frequency emission below 40 MHz. The decimeter wavelength emission is considered, taking into account the discovery of synchrotron emission, radiation by high-energy electrons in a magnetic field, and the present status of Jovian synchrotron phenomenology. Attention is also given to the decameter and hectometer wavelength emission, and emissions at kilometric wavelengths.

  4. Towards a Realistic Pulsar Magnetosphere

    Science.gov (United States)

    Kalapotharakos, Constantinos; Kazanas, Demosthenes; Harding, Alice; Contopoulos, Ioannis

    2012-01-01

    We present the magnetic and electric field structures as well as the currents ami charge densities of pulsar magnetospberes which do not obey the ideal condition, E(raised dot) B = O. Since the acceleration of particles and the production of radiation requires the presence of an electric field component parallel to the magnetic field, E(sub ll) the structure of non-Ideal pulsar magnetospheres is intimately related to the production of pulsar radiation. Therefore, knowledge of the structure of non-Ideal pulsar maglletospheres is important because their comparison (including models for t he production of radiation) with observations will delineate the physics and the parameters underlying the pulsar radiation problem. We implement a variety of prescriptions that support nonzero values for E(sub ll) and explore their effects on the structure of the resulting magnetospheres. We produce families of solutions that span the entire range between the vacuum and the (ideal) Force-Free Electrodynamic solutions. We also compute the amount of dissipation as a fraction of the Poynting flux for pulsars of different angles between the rotation and magnetic axes and conclude that tltis is at most 20-40% (depending on t he non-ideal prescription) in the aligned rotator and 10% in the perpendicular one. We present also the limiting solutions with the property J = pc and discuss their possible implicatioll on the determination of the "on/ off" states of the intermittent pulsars. Finally, we find that solutions with values of J greater than those needed to null E(sub ll) locally produce oscillations, potentially observable in the data.

  5. Detection of the Magnetospheric Emissions from Extrasolar Planets

    Science.gov (United States)

    Lazio, J.

    2014-12-01

    Planetary-scale magnetic fields are a window to a planet's interior and provide shielding of the planet's atmosphere. The Earth, Mercury, Ganymede, and the giant planets of the solar system all contain internal dynamo currents that generate planetary-scale magnetic fields. These internal dynamo currents arise from differential rotation, convection, compositional dynamics, or a combination of these. If coupled to an energy source, such as the incident kinetic or magnetic energy from the solar wind, a planet's magnetic field can produce electron cyclotron masers in its magnetic polar regions. The most well known example of this process is the Jovian decametric emission, but all of the giant planets and the Earth contain similar electron cyclotron masers within their magnetospheres. Extrapolated to extrasolar planets, the remote detection of the magnetic field of an extrasolar planet would provide a means of obtaining constraints on the thermal state, composition, and dynamics of its interior as well as improved understanding of the basic planetary dynamo process. The magnetospheric emissions from solar system planets and the discovery of extrasolar planets have motivated both theoretical and observational work on magnetospheric emissions from extrasolar planets. Stimulated by these advances, the W.M. Keck Institute for Space Studies hosted a workshop entitled "Planetary Magnetic Fields: Planetary Interiors and Habitability." I summarize the current observational status of searches for magnetospheric emissions from extrasolar planets, based on observations from a number of ground-based radio telescopes, and future prospects for ground-based studies. Using the solar system planetary magnetic fields as a guide, future space-based missions will be required to study planets with magnetic field strengths lower than that of Jupiter. I summarize mission concepts identified in the KISS workshop, with a focus on the detection of planetary electron cyclotron maser emission. The

  6. Using the Aurora to Remote Sense Near-Earth Space

    Science.gov (United States)

    Donovan, Eric

    2012-10-01

    The Earth's magnetosphere is formed by the interaction of the solar wind and Earth's magnetic field. Sitting like a giant wind sock in the solar wind, the magnetosphere is an enormous and dynamic region. The processes at work within the magnetosphere serve as exemplars of phenomena that happen throughout the cosmos, and have consequences in the upper atmosphere. One of those is the aurora, a truly global and multi-scale phenomenon that we are only beginning to understand. Of all the countries on Earth, Canada has the largest region of land under the auroral zone, something Canadian scientists have capitalized on for more than fifty years. In this talk, I will outline how we use observations of the aurora to remote sense the magnetosphere, focusing on Canadian ground-based and space-based programs that provide remarkable images of this beautiful natural phenomenon.

  7. Decoding solar wind-magnetosphere coupling

    Science.gov (United States)

    Beharrell, M. J.; Honary, F.

    2016-10-01

    We employ a new NARMAX (Nonlinear Auto-Regressive Moving Average with eXogenous inputs) code to disentangle the time-varying relationship between the solar wind and SYM-H. The NARMAX method has previously been used to formulate a Dst model, using a preselected solar wind coupling function. In this work, which uses the higher-resolution SYM-H in place of Dst, we are able to reveal the individual components of different solar wind-magnetosphere interaction processes as they contribute to the geomagnetic disturbance. This is achieved with a graphics processing unit (GPU)-based NARMAX code that is around 10 orders of magnitude faster than previous efforts from 2005, before general-purpose programming on GPUs was possible. The algorithm includes a composite cost function, to minimize overfitting, and iterative reorthogonalization, which reduces computational errors in the most critical calculations by a factor of ˜106. The results show that negative deviations in SYM-H following a southward interplanetary magnetic field (IMF) are first a measure of the increased magnetic flux in the geomagnetic tail, observed with a delay of 20-30 min from the time the solar wind hits the bow shock. Terms with longer delays are found which represent the dipolarization of the magnetotail, the injections of particles into the ring current, and their subsequent loss by flowout through the dayside magnetopause. Our results indicate that the contribution of magnetopause currents to the storm time indices increase with solar wind electric field, E = v × B. This is in agreement with previous studies that have shown that the magnetopause is closer to the Earth when the IMF is in the tangential direction.

  8. Challenges Handling Magnetospheric and Ionospheric Signals in Internal Geomagnetic Field Modelling

    Science.gov (United States)

    Finlay, C. C.; Lesur, V.; Thébault, E.; Vervelidou, F.; Morschhauser, A.; Shore, R.

    2016-09-01

    Measurements of the Earth's magnetic field collected by low-Earth-orbit satellites such as Swarm and CHAMP, as well as at ground observatories, are dominated by sources in the Earth's interior. However these measurements also contain significant contributions from more rapidly-varying current systems in the ionosphere and magnetosphere. In order to fully exploit magnetic data to probe the physical properties and dynamics of the Earth's interior, field models with suitable treatments of external sources, and their associated induced signals, are essential. Here we review the methods presently used to construct models of the internal field, focusing on techniques to handle magnetospheric and ionospheric signals. Shortcomings of these techniques often limit the quality, as well as spatial and temporal resolution, of internal field models. We document difficulties in using track-by-track analysis to characterize magnetospheric field fluctuations, differences in internal field models that result from alternative treatments of the quiet-time ionospheric field, and challenges associated with rapidly changing, but spatially correlated, magnetic signatures of polar cap current systems. Possible strategies for improving internal field models are discussed, many of which are described in more detail elsewhere in this volume.

  9. Modeling of plasma density in the earth's dayside inner magnetosphere

    NARCIS (Netherlands)

    Domrachev, VV; Chugunin, DV

    2002-01-01

    The results of comparison of the model profiles of density, obtained by means of the CDPDM model, with the experimental data of the ISEE-1 satellite for the years 1977-1983 are presented. The hypothesis on the validity of the mirror mapping of the convection boundary relative to the dawn-dusk

  10. The Magnetospheric Cusps Structure and Dynamics

    CERN Document Server

    Fritz, Theodore A

    2005-01-01

    This collection of papers will address the question "What is the Magnetospheric Cusp?" and what is its role in the coupling of the solar wind to the magnetosphere as well as its role in the processes of particle transport and energization within the magnetosphere. The cusps have traditionally been described as narrow funnel-shaped regions that provide a focus of the Chapman-Ferraro currents that flow on the magnetopause, a boundary between the cavity dominated by the geomagnetic field (i.e., the magnetosphere) and the external region of the interplanetary medium. Measurements from a number of recent satellite programs have shown that the cusp is not confined to a narrow region near local noon but appears to encompass a large portion of the dayside high-latitude magnetosphere and it appears that the cusp is a major source region for the production of energetic charged particles for the magnetosphere. Audience: This book will be of interest to space science research organizations in governments and industries, ...

  11. Space weather: Why are magnetospheric physicists interested in solar explosive phenomena

    Science.gov (United States)

    Koskinen, H. E. J.; Pulkkinen, T. I.

    That solar activity drives magnetospheric dynamics has for a long time been the basis of solar-terrestrial physics. Numerous statistical studies correlating sunspots, 10.7 cm radiation, solar flares, etc., with various magnetospheric and geomagnetic parameters have been performed. However, in studies of magnetospheric dynamics the role of the Sun has often remained in the background and only the actual solar wind impinging the magnetosphere has gained most of the attention. During the last few years a new applied field of solar-terrestrial physics, space weather, has emerged. The term refers to variable particle and field conditions in our space environment, which may be hazardous to space-borne or ground-based technological systems and can endanger human life and health. When the modern society is becoming increasingly dependent on space technology, the need for better modelling and also forecasting of space weather becomes urgent. While for post analysis of magnetospheric phenomena it is quite sufficient to include observations from the magnetospheric boundaries out to L1 where SOHO is located, these observations do not provide enough lead-time to run space weather forecasting models and to distribute the forecasts to potential customers. For such purposes we need improved physical understanding and models to predict which active processes on the Sun will impact the magnetosphere and what their expected consequences are. An important change of view on the role of the Sun as the origin of magnetospheric disturbances has taken place during last 10--20 years. For a long time, the solar flares were thought to be the most geoeffective solar phenomena. Now the attention has shifted much more towards coronal mass ejections and the SOHO coronal observations seem to have turned the epoch irreversibly. However, we are not yet ready to make reliable perdictions of the terrestrial environment based on CME observations. From the space weather viewpoint, the key questions are

  12. MESSENGER Observations of Magnetic Reconnection in Mercury's Magnetosphere

    Science.gov (United States)

    Slavin. James A.

    2009-01-01

    During MESSENGER'S second flyby of Mercury on October 6,2008, very intense reconnection was observed between the planet's magnetic field and a steady southward interplanetary magnetic field (IMF). The dawn magnetopause was threaded by a strong magnetic field normal to its surface, approx.14 nT, that implies a rate of reconnection approx.10 times the typical rate at Earth and a cross-magnetospheric electric potential drop of approx.30 kV. The highest magnetic field observed during this second flyby, approx.160 nT, was found at the core of a large dayside flux transfer event (FTE). This FTE is estimated to contain magnetic flux equal to approx.5% that of Mercury's magnetic tail or approximately one order of magnitude higher fraction of the tail flux than is typically found for FTEs at Earth. Plasmoid and traveling compression region (TCR) signatures were observed throughout MESSENGER'S traversal of Mercury's magnetotail with a repetition rate comparable to the Dungey cycle time of approx.2 min. The TCR signatures changed from south-north, indicating tailward motion, to north-south, indicating sunward motion, at a distance approx.2.6 RM (where RM is Mercury's radius) behind the terminator indicating that the near-Mercury magnetotail neutral line was crossed at that point. Overall, these new MESSENGER observations suggest that magnetic reconnection at the dayside magnetopause is very intense relative to what is found at Earth and other planets, while reconnection in Mercury's tail is similar to that in other planetary magnetospheres, but with a very short Dungey cycle time.

  13. Saturn's magnetosphere: An example of dynamic planetary systems

    Science.gov (United States)

    Krimigis, Stamatios M.

    2011-01-01

    Planetary magnetospheres are prime examples of interacting plasma regimes at different scales. There is the principal interaction with the solar wind that seems to be the main driver of the dynamics at Mercury and Earth. But these inner planet magnetospheres are relatively simple when compared to those of the outer planets which are primarily driven by planetary rotation and include internal plasma sources from various moons and rings, in addition to those from the planetary ionospheres and the solar wind. Io's volcanic source at Jupiter is a prime example, but now Enceladus at Saturn has joined the fray, while Titan is a surprisingly minor player despite its thick nitrogen atmosphere and its continued bombardment by energetic particles. Mass loading of plasma leads to interchange instability in the inner magnetospheres at both Jupiter and Saturn, while ionospheric slippage, among other processes, seems to contribute to a variable rotation period in the spin-aligned dipole field of Saturn, manifested in auroral kilometric radiation (SKR), components of the magnetic field itself, and the plasma periodicities measured at several energies. Through use of the ENA (energetic neutral atom) technique, it is now possible to observe bulk motions of the plasma and their connection to planetary auroral processes. Such imaging at Saturn by Cassini has revealed the location of a region of post-midnight acceleration events that seem to corotate with the planet and coincide with auroral brightening and SKR. Periodic injections of plasma have been identified and repeat at the Kronian rotation period of 10.8 hours. A semi-permanent but asymmetric ring current has also been imaged, located between the orbits of the satellites Rhea (~9 RS) and Titan (~20 RS), with a maximum at ~10+/- 1RS and dominated by the hot (>3 keV) plasma component.

  14. Corotation-driven magnetosphere-ionosphere coupling currents in Saturn’s magnetosphere and their relation to the auroras

    Directory of Open Access Journals (Sweden)

    S. W. H. Cowley

    to expectations for corotation-related currents. We thus conclude that Saturn’s ‘main oval’ auroras are not associated with corotation-enforcing currents as they are at Jupiter, but instead are most probably associated with coupling to the solar wind as at Earth. At the same time, the Voyager flow observations also suggest the presence of radially localized ‘dips’ in the plasma angular velocity associated with the moons Dione and Rhea, which are ~ 1–2 RS in radial extent in the equatorial plane. The presence of such small-scale flow features, assumed to be azimuthally extended, results in localized several-MA enhancements in the ionospheric Pedersen current, and narrow bi-polar signatures in the field-aligned currents which peak at values an order of magnitude larger than those associated with the large-scale currents. Narrow auroral rings (or partial rings ~ 0.25° co-latitude wide with intensities ~ 1 kiloRayleigh may be formed in the regions of upward field-aligned current under favourable circumstances, located at co-latitudes between ~ 17° and ~ 20° in the north, and ~ 19° and ~22° in the south.

    Key words. Magnetospheric physics (current systems; magnetosphere-ionosphere interactions; planetary magnetospheres

  15. Magnetic effects of magnetospheric currents at ground and in low orbit

    DEFF Research Database (Denmark)

    Stolle, Claudia; Naemi Willer, Anna; Finlay, Chris

    to diminish with reducing solar activity (as was previously noted by Lühr & Maus, 2010), while the slope is hardly affected. There have been several suggestions for the origin of this systematic difference between ground and space based observations of magnetospheric fields. We compare magnetic residuals...... of selected observatories with those of CHAMP satellite observations at times of conjunctions, separating the data pairs by criteria including local time and longitude, season, solar and magnetic activity. Obtaining rough estimates of the ionospheric conductivity in this way, we are able to discuss possible...... field model from Magsat vector data. Geophys. Res. Lett. 7:793-96 Lühr H, Maus S. 2010. Solar cycle dependence of quiet-time magnetospheric currents and a model of their near-Earth magnetic fields. Earth Planets Space 62:843-48...

  16. A quantitative magnetospheric model derived from spacecraft magnetometer data

    Science.gov (United States)

    Mead, G. D.; Fairfield, D. H.

    1975-01-01

    The model is derived by making least squares fits to magnetic field measurements from four Imp satellites. It includes four sets of coefficients, representing different degrees of magnetic disturbance as determined by the range of Kp values. The data are fit to a power series expansion in the solar magnetic coordinates and the solar wind-dipole tilt angle, and thus the effects of seasonal north-south asymmetries are contained. The expansion is divergence-free, but unlike the usual scalar potential expansion, the model contains a nonzero curl representing currents distributed within the magnetosphere. The latitude at the earth separating open polar cap field lines from field lines closing on the day side is about 5 deg lower than that determined by previous theoretically derived models. At times of high Kp, additional high-latitude field lines extend back into the tail. Near solstice, the separation latitude can be as low as 75 deg in the winter hemisphere. The average northward component of the external field is much smaller than that predicted by theoretical models; this finding indicates the important effects of distributed currents in the magnetosphere.

  17. Magnetospheric Atmospheric X-ray Imaging Experiment (MAXIE)

    Science.gov (United States)

    Imhof, W. L.; Voss, H. D.; Mobilia, J.; Datlowe, D. W.; Chinn, V. L.; Hilsenrath, M.; Vondrak, R. R.

    1996-01-01

    This report summarizes the activities sponsored by the Office of Naval Research for the Magnetospheric Atmospheric X-ray Imaging Experiment (MAXIE). The MAXIE instrument was developed as a joint activity of Lockheed, The Aerospace Corporation, and the University of Bergen, Norway. Lockheed was responsible for the overall management of the program, interfacing with the appropriate government agencies, the overall electrical and mechanical design, flight software, environmental testing, spacecraft integration activities, on orbit checkout, and data processing activities. The Magnetospheric Atmospheric X-ray Imaging Experiment (MAXIE), the ONR 401 experiment, is the first in a new class of satellite-borne remote sensing instruments. The primary innovation is the ability to obtain rapid, sequential, images with high sensitivity of the earth's X ray aurora from a low altitude polar orbiting satellite. These images can be used to identify dynamic temporal variations in the three-dimensional (energy and position) distribution of electron precipitation into the atmosphere. MAXIE was launched on the TIROS NOAA-13 satellite on 9 August 1993. The experiment performed well during its turn-on sequence; however, the spacecraft bus failed on 21 August 1993. New spacebased technologies successfully used in MAXIE were mixed-mode ASIC microcircuits, a zero torque scanning system with associated viscoelastic damping, a paraffin stow release mechanism, a parallel integrating PHA processor, a low noise Si(Li) sensor telescope, and an advanced thermal cooling system. MAXIE's on orbit operation, control of penetrating particle backgrounds, and scientific data indicated good overall performance.

  18. The influence of solar wind variability on magnetospheric ULF wave power

    Energy Technology Data Exchange (ETDEWEB)

    Pokhotelov, D.; Rae, I.J. [UCL, Dorking (United Kingdom). Mullard Space Science Lab.; Murphy, K.R. [NASA Goddard Space Flight Center, Greenbelt, MD (United States); Mann, I.R. [Alberta Univ., Edmonton, AB (Canada). Dept. of Physics

    2015-10-01

    Magnetospheric ultra-low frequency (ULF) oscillations in the Pc 4-5 frequency range play an important role in the dynamics of Earth's radiation belts, both by enhancing the radial diffusion through incoherent interactions and through the coherent drift-resonant interactions with trapped radiation belt electrons. The statistical distributions of magnetospheric ULF wave power are known to be strongly dependent on solar wind parameters such as solar wind speed and interplanetary magnetic field (IMF) orientation. Statistical characterisation of ULF wave power in the magnetosphere traditionally relies on average solar wind-IMF conditions over a specific time period. In this brief report, we perform an alternative characterisation of the solar wind influence on magnetospheric ULF wave activity through the characterisation of the solar wind driver by its variability using the standard deviation of solar wind parameters rather than a simple time average. We present a statistical study of nearly one solar cycle (1996-2004) of geosynchronous observations of magnetic ULF wave power and find that there is significant variation in ULF wave powers as a function of the dynamic properties of the solar wind. In particular, we find that the variability in IMF vector, rather than variabilities in other parameters (solar wind density, bulk velocity and ion temperature), plays the strongest role in controlling geosynchronous ULF power. We conclude that, although time-averaged bulk properties of the solar wind are a key factor in driving ULF powers in the magnetosphere, the solar wind variability can be an important contributor as well. This highlights the potential importance of including solar wind variability especially in studies of ULF wave dynamics in order to assess the efficiency of solar wind-magnetosphere coupling.

  19. Stellar wind-magnetosphere interaction at exoplanets: computations of auroral radio powers

    Science.gov (United States)

    Nichols, J. D.; Milan, S. E.

    2016-09-01

    We present calculations of the auroral radio powers expected from exoplanets with magnetospheres driven by an Earth-like magnetospheric interaction with the solar wind. Specifically, we compute the twin cell-vortical ionospheric flows, currents, and resulting radio powers resulting from a Dungey cycle process driven by dayside and nightside magnetic reconnection, as a function of planetary orbital distance and magnetic field strength. We include saturation of the magnetospheric convection, as observed at the terrestrial magnetosphere, and we present power-law approximations for the convection potentials, radio powers and spectral flux densities. We specifically consider a solar-age system and a young (1 Gyr) system. We show that the radio power increases with magnetic field strength for magnetospheres with saturated convection potential, and broadly decreases with increasing orbital distance. We show that the magnetospheric convection at hot Jupiters will be saturated, and thus unable to dissipate the full available incident Poynting flux, such that the magnetic Radiometric Bode's Law (RBL) presents a substantial overestimation of the radio powers for hot Jupiters. Our radio powers for hot Jupiters are ˜5-1300 TW for hot Jupiters with field strengths of 0.1-10 BJ orbiting a Sun-like star, while we find that competing effects yield essentially identical powers for hot Jupiters orbiting a young Sun-like star. However, in particular, for planets with weaker magnetic fields, our powers are higher at larger orbital distances than given by the RBL, and there are many configurations of planet that are expected to be detectable using SKA.

  20. Multi-fluid simulations of the coupled solar wind-magnetosphere-ionsphere system

    Science.gov (United States)

    Lyon, J.

    2011-12-01

    This paper will review recent work done with the multi-fluid version of the Lyon-Fedder-Mobarry (MF-LFM) global MHD simulation code. We will concentrate on O+ outflow from the ionosphere and its importance for magnetosphere-ionosphere (MI) coupling and also the importance of ionospheric conditions in determining the outflow. While the predominant method of coupling between the magnetosphere and ionosphere is electrodynamic, it has become apparent the mass flows from the ionosphere into the magnetosphere can have profound effects on both systems. The earliest models to attempt to incorporate this effect used very crude clouds of plasma near the Earth. The earliest MF-LFM results showed that depending on the details of the outflow - where, how much, how fast - very different magnetospheric responses could be found. Two approaches to causally driven models for the outflow have been developed for use in global simulations, the Polar Wind Outflow Model (PWOM), started at the Univ. of Michigan, and the model used by Bill Lotko and co-workers at Dartmouth. We will give a quick review of this model which is based on the empirical relation between outflow fluence and Poynting flux discovered by Strangeway. An additional factor used in this model is the precipitating flux of electrons, which is presumed to correlate with the scale height of the upwelling ions. parameters such as outflow speed and density are constrained by the total fluence. The effects of the outflow depend on the speed. Slower outflow tends to land in the inner magnetosphere increasing the strength of the ring current. Higher speed flow out in the tail. Using this model, simulations have shown that solar wind dynamic pressure has a profound effect on the amount of fluence. The most striking result has been the simulation of magnetospheric sawtooth events. We will discuss future directions for this research, emphasizing the need for better physical models for the outflow process and its coupling to the

  1. Evidence for Corotating Convection in Saturn's Magnetosphere

    Science.gov (United States)

    Kivelson, M. G.; Southwood, D. J.; Dougherty, M. K.

    2006-05-01

    Saturn's magnetic field exhibits a high degree of azimuthal symmetry, yet the field and plasma signatures of the magnetosphere are modulated at a period close to that of planetary rotation. How, then, is a clear periodicity imposed on the magnetic field and plasma of the planetary magnetosphere? In this talk, Cassini magnetometer data are used to develop a scenario for the dynamics of the Saturn magnetosphere. The proposal is that mass transport, accomplished in the inner magnetosphere by interchange motion, feeds into the outer magnetosphere where ballooning driven by centrifugal stress leads to outward transport, field reconnection and plasma loss in a favored local time sector; flux is transported inward in other regions. The model is closely related to the concept of corotating convection proposed by Dessler, Hill, and co-workers for Jupiter. The proposed mechanism can be consistent with aspects of the empirical camshaft model introduced by Espinosa et al., 2003 to explain Pioneer and Voyager magnetometer data. Anomalous transport here proposed could originate from a localized ionospheric conductivity anomaly. The resulting cyclic stress modulates the current in the current sheet and can account for its north-south excursions. The convection patterns proposed also imply that corotating, field-aligned currents would be a basic feature of the Saturn system.

  2. Magnetospheric "anti-glitches" in magnetars

    CERN Document Server

    Lyutikov, Maxim

    2013-01-01

    We attribute the rapid spindown of magnetar 1E 2259+586 observed by Archibald et al. (2013), termed the "anti-glitch", to partial opening of the magnetosphere during the X-ray burst, followed by changes of the structure of the closed field line region. To account for the observed spin decrease during the X- ray flare all that is needed is the transient opening, for just one period, of a relatively small fraction of the magnetosphere, of the order of only few percent. More generally, we argue that in magnetars all timing irregularities have magnetospheric origin and are induced either by (i) the fluctuations in the current structure of the magnetosphere (similar to the long term torque variations in the rotationally powered pulsars); or, specifically to magnetars, by (ii) opening of a fraction of the magnetosphere during bursts and flares - the latter events are always accompanied by rapid spindown, an "anti-glitch". Slow rotational motion of the neutron star crust, driven by crustal magnetic fields, leads bey...

  3. Cluster observation of electron energization during the magnetospheric reconnection

    Science.gov (United States)

    Gurram, Harsha; Egedal, Jan

    2016-10-01

    In situ spacecraft measurements in the Earths magnetosphere have shown that magnetic reconnection energizes the electrons and a source of the suprathermal electrons. This study investigates the electron distribution functions and electron heating recorded by the Cluster Mission during the reconnection event on August 21, 2002 in the interval 0754 to 0825. This event exhibits a flow reversal with the characteristic isotropic flat-top distribution around the flow reversal namely near the X-line. The distribution function measurements near reconnection reveal the presence of cold beams directed towards the X-line while the energized electrons are seen to be moving away from the reconnection region. The electrons see an increase in their bulk energy by a factor of 100 from the inflow to exhaust. The observed beam like features are in good agreement with the kinetic simulations and confirm the model for electron energization in reconnection exhaust.

  4. Comparative Analysis of Dayside Reconnection Models in Global Magnetosphere Simulations

    CERN Document Server

    Komar, C M; Cassak, P A

    2015-01-01

    We test and compare a number of existing models predicting the location of magnetic reconnection at Earth's dayside magnetopause for various solar wind conditions. We employ robust image processing techniques to determine the locations where each model predicts reconnection to occur. The predictions are then compared to the magnetic separators, the magnetic field lines separating different magnetic topologies. The predictions are tested in distinct high-resolution simulations with interplanetary magnetic field (IMF) clock angles ranging from 30 to 165 degrees in global magnetohydrodynamic simulations using the three-dimensional Block-Adaptive Tree Solarwind Roe-type Upwind Scheme (BATS-R-US) code with a uniform resistivity, although the described techniques can be generally applied to any self-consistent magnetosphere code. Additional simulations are carried out to test location model dependence on IMF strength and dipole tilt. We find that most of the models match large portions of the magnetic separators wh...

  5. Polarized Curvature Radiation in Pulsar Magnetosphere

    CERN Document Server

    Wang, P F; Han, J L

    2014-01-01

    The propagation of polarized emission in pulsar magnetosphere is investigated in this paper. The polarized waves are generated through curvature radiation from the relativistic particles streaming along curved magnetic field lines and co-rotating with the pulsar magnetosphere. Within the 1/{\\deg} emission cone, the waves can be divided into two natural wave mode components, the ordinary (O) mode and the extraord nary (X) mode, with comparable intensities. Both components propagate separately in magnetosphere, and are aligned within the cone by adiabatic walking. The refraction of O-mode makes the two components separated and incoherent. The detectable emission at a given height and a given rotation phase consists of incoherent X-mode and O-mode components coming from discrete emission regions. For four particle-density models in the form of uniformity, cone, core and patches, we calculate the intensities for each mode numerically within the entire pulsar beam. If the co-rotation of relativistic particles with...

  6. Magnetospheric outflows in young stellar objects

    Directory of Open Access Journals (Sweden)

    Zanni Claudio

    2014-01-01

    Full Text Available Different classes of outflows are associated with the magnetospheric activity of accreting T Tauri protostars. Stellar winds are accelerated along the open field lines anchored in the stellar surface; disk winds (extended or X-type can be launched along the open magnetic surfaces threading the accretion disk; another type of ejection can arise from the region of interaction of the closed magnetosphere with the accretion disk (magnetospheric ejections, conical winds, where the magnetic surfaces undergo quasiperiodic episodes of inflation and reconnection. In this chapter I will present the main dynamical properties of these different types of outflow. Two main issues will be addressed. First, I will try to understand if these ejection phenomena can account for the origin of the jets often observed in young forming stellar systems. Second, I will evaluate the impact of these outflows on the angular momentum evolution of the central protostar.

  7. Spacetime approach to force-free magnetospheres

    CERN Document Server

    Gralla, Samuel E

    2014-01-01

    Force-Free Electrodynamics (FFE) describes magnetically dominated relativistic plasma via non-linear equations for the electromagnetic field alone. Such plasma is thought to play a key role in the physics of pulsars and active black holes. Despite its simple covariant formulation, FFE has primarily been studied in 3+1 frameworks, where spacetime is split into space and time. In this article we systematically develop the theory of force-free magnetospheres taking a spacetime perspective. Using a suite of spacetime tools and techniques (notably exterior calculus) we cover 1) the basics of the theory, 2) exact solutions that demonstrate the extraction and transport of the rotational energy of a compact object (in the case of a black hole, the Blandford-Znajek mechanism), 3) the behavior of current sheets, 4) the general theory of stationary, axisymmetric magnetospheres and 5) general properties of pulsar and black hole magnetospheres. We thereby synthesize, clarify and generalize known aspects of the physics of ...

  8. Theory of pulsar magnetosphere and wind

    CERN Document Server

    Pétri, J

    2016-01-01

    Neutron stars are fascinating astrophysical objects immersed in strong gravitational and electromagnetic fields, at the edge of our current theories. These stars manifest themselves mostly as pulsars, emitting a timely very stable and regular electromagnetic signal. Even though discovered almost fifty years ago, they still remain mysterious compact stellar objects. In this review, we summarize the most fundamental theoretical aspects of neutron star magnetospheres and winds. The main competing models susceptible to explain their radiative properties like multi-wavelength pulse shapes and spectra and the underlying physical processes such as pair creation and radiation mechanisms are scrutinized. A global but still rather qualitative picture emerges slowly thanks to recent advances in numerical simulations on the largest scales. However considerations about pulsar magnetospheres remain speculative. For instance the exact composition of the magnetospheric plasma is not yet known. Is it solely filled with a mixt...

  9. Radial plasma transport in Saturn's magnetosphere (Invited)

    Science.gov (United States)

    Hill, T. W.

    2010-12-01

    Radial plasma transport in the magnetosphere of Saturn, like that of Jupiter, is driven by the centrifugal force of (partial) corotation acting on internally generated plasma. A significant difference is that the internal plasma source is evidently broadly distributed throughout the inner magnetosphere of Saturn (4 CAPS and MAG), and reproduced in numerical simulations (RCM) that contain a distributed plasma source, although it has not, to my knowledge, been explained by an analytical theory containing an active plasma source. Both planets exhibit strong magnetospheric modulations near the planetary spin period, probably indicating a persistent longitudinal asymmetry of the radial plasma transport process. At Jupiter such an asymmetry is readily understood as a consequence of the dramatic asymmetry of the intrinsic planetary magnetic field. This is not so at Saturn, where any such field asymmetry is known to be very modest at best. In neither case has the precise nature of the asymmetry been identified either observationally or theoretically.

  10. MHD-EPIC: Extended Magnetohydrodynamics with Embedded Particle-in-Cell Simulation of Ganymede's Magnetosphere.

    Science.gov (United States)

    Toth, G.; Daldorff, L. K. S.; Jia, X.; Gombosi, T. I.; Lapenta, G.

    2014-12-01

    We have recently developed a new modeling capability to embed theimplicit Particle-in-Cell (PIC) model iPIC3D into the BATS-R-USmagnetohydrodynamic model. The PIC domain can cover the regions wherekinetic effects are most important, such as reconnection sites. TheBATS-R-US code, on the other hand, can efficiently handle the rest ofthe computational domain where the MHD or Hall MHD description issufficient. As one of the very first applications of the MHD-EPICalgorithm (Daldorff et al. 2014, JCP, 268, 236) we simulate theinteraction between Jupiter's magnetospheric plasma with Ganymede'smagnetosphere, where the separation of kinetic and global scalesappears less severe than for the Earth's magnetosphere. Because theexternal Jovian magnetic field remains in an anti-parallel orientationwith respect to Ganymede's intrinsic magnetic field, magneticreconnection is believed to be the major process that couples the twomagnetospheres. As the PIC model is able to describe self-consistentlythe electron behavior, our coupled MHD-EPIC model is well suited forinvestigating the nature of magnetic reconnection in thisreconnection-driven mini-magnetosphere. We will compare the MHD-EPICsimulations with pure Hall MHD simulations and compare both modelresults with Galileo plasma and magnetic field measurements to assess therelative importance of ion and electron kinetics in controlling theconfiguration and dynamics of Ganymede's magnetosphere.

  11. Challenges in Measuring External Currents Driven by the Solar Wind-Magnetosphere Interaction

    Directory of Open Access Journals (Sweden)

    Guan Le

    2015-01-01

    Full Text Available In studying the _ geomagnetism it has always been a challenge to separate the external currents originating from the ionosphere and magnetosphere. While the internal magnetic field changes very slowly in time scales of years and more, the ionospheric and magnetospheric current systems driven by the solar wind-magnetosphere interaction are very dynamic. They are intimately controlled by the ionospheric electrodynamics and ionosphere-magnetosphere coupling. Single spacecraft observations are not able to separate their spatial and temporal variations, and thus to accurately describe their configurations. To characterize and understand the external currents, satellite observations require both good spatial and temporal resolutions. This paper reviews our observations of the external currents from two recent Low Earth Orbit (LEO satellite missions: Space Technology 5 (ST-5, _ first three-satellite constellation mission in LEO polar orbit and Communications/Navigation Outage Forecasting System (C/NOFS, an equatorial satellite developed by the US Air Force Research Laboratory. We present recommendations for future geomagnetism missions based on these observations.

  12. Theoretical study of electromagnetic electron cyclotron waves in the presence of AC field in Uranian magnetosphere

    Science.gov (United States)

    Pandey, R. S.; Kaur, Rajbir

    2015-10-01

    Electromagnetic electron cyclotron (EMEC) waves with temperature anisotropy in the magnetosphere of Uranus have been studied in present work. EMEC waves are investigated using method of characteristic solution by kinetic approach, in presence of AC field. In 1986, Voyager 2 encounter with Uranus revealed that magnetosphere of Uranus exhibit non-Maxwellian high-energy tail distribution. So, the dispersion relation, real frequency and growth rate are evaluated using Lorentzian Kappa distribution function. Effect of temperature anisotropy, AC frequency and number density of particles is found. The study is also extended to oblique propagation of EMEC waves in presence and absence of AC field. Through comprehensive mathematical analysis it is found that when EMEC wave propagates parallel to intrinsic magnetic field of Uranus, its growth is more enhanced than in case of oblique propagation. Results are also discussed in context to magnetosphere of Earth and also gives theoretical explanation to existence of high energetic particles observed by Voyager 2 in the magnetosphere of Uranus. The results can present a further insight into the nature of electron-cyclotron instability condition for the whistler mode waves in the outer radiation belts of Uranus or other space plasmas.

  13. Two Dual Ion Spectrometer Flight Units of the Fast Plasma Instrument Suite (FPI) for the Magnetospheric Multiscale Mission (MMS)

    Science.gov (United States)

    Adams, Mitzi

    2014-01-01

    Two Dual Ion Spectrometer flight units of the Fast Plasma Instrument Suite (FPI) for the Magnetospheric Multiscale Mission (MMS) have returned to MSFC for flight testing. Anticipated to begin on June 30, tests will ensue in the Low Energy Electron and Ion Facility of the Heliophysics and Planetary Science Office (ZP13), managed by Dr. Victoria Coffey of the Natural Environments Branch of the Engineering Directorate (EV44). The MMS mission consists of four identical spacecraft, whose purpose is to study magnetic reconnection in the boundary regions of Earth's magnetosphere.

  14. Theory of pulsar magnetosphere and wind

    Science.gov (United States)

    Pétri, Jérôme

    2016-10-01

    > leptons or does it contain a non-negligible fraction of protons and/or ions? Is it almost entirely filled or mostly empty except for some small anecdotal plasma filled regions? Answers to these questions will strongly direct the description of the magnetosphere to seemingly contradictory results leading sometimes to inconsistencies. Nevertheless, accounts are given as to the latest developments in the theory of pulsar magnetospheres and winds, the existence of a possible electrosphere and physical insight obtained from related observational signatures of multi-wavelength pulsed emission.

  15. Dusty plasma around Enceladus affects Saturn's magnetosphere

    Science.gov (United States)

    Balcerak, Ernie

    2012-02-01

    Scientists have been puzzled by periodic bursts of radiation, known as the Saturn kilometric radiation (SKR), that occur in the planet's magnetosphere. These emissions occur at a rate that is close to, but not quite the same as, the rate at which the planet rotates. New observations from the Cassini Spacecraft's flybys of Saturn's moon Enceladus in 2008 are revealing new details about the plasma environment around Enceladus and how it may affect Saturn's magnetosphere. These observations could also shed some light on the SKR rotation rate.

  16. Magnetospheric structure of rotation powered pulsars

    Energy Technology Data Exchange (ETDEWEB)

    Arons, J. (California Univ., Berkeley, CA (USA) California Univ., Livermore, CA (USA). Inst. of Geophysics and Planetary Physics)

    1991-01-07

    I survey recent theoretical work on the structure of the magnetospheres of rotation powered pulsars, within the observational constraints set by their observed spindown, their ability to power synchrotron nebulae and their ability to produce beamed collective radio emission, while putting only a small fraction of their energy into incoherent X- and gamma radiation. I find no single theory has yet given a consistent description of the magnetosphere, but I conclude that models based on a dense outflow of pairs from the polar caps, permeated by a lower density flow of heavy ions, are the most promising avenue for future research. 106 refs., 4 figs., 2 tabs.

  17. Storm- Time Dynamics of Ring Current Protons: Implications for the Long-Term Energy Budget in the Inner Magnetosphere.

    Science.gov (United States)

    Gkioulidou, M.; Ukhorskiy, A. Y.; Mitchell, D. G.; Lanzerotti, L. J.

    2015-12-01

    The ring current energy budget plays a key role in the global electrodynamics of Earth's space environment. Pressure gradients developed in the inner magnetosphere can shield the near-Earth region from solar wind-induced electric fields. The distortion of Earth's magnetic field due to the ring current affects the dynamics of particles contributing both to the ring current and radiation belts. Therefore, understanding the long-term evolution of the inner magnetosphere energy content is essential. We have investigated the evolution of ring current proton pressure (7 - 600 keV) in the inner magnetosphere based on data from the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instrument aboard Van Allen Probe B throughout the year 2013. We find that although the low-energy component of the protons (governed by convective timescales and is very well correlated with the Dst index, the high-energy component (>100 keV) varies on much longer timescales and shows either no or anti-correlation with the Dst index. Interestingly, the contributions of the high- and low-energy protons to the total energy content are comparable. Our results indicate that the proton dynamics, and as a consequence the total energy budget in the inner magnetosphere (inside geosynchronous orbit), is not strictly controlled by storm-time timescales as those are defined by the Dst index.

  18. Wave energy budget analysis in the Earth's radiation belts uncovers a missing energy

    National Research Council Canada - National Science Library

    Artemyev, A V; Agapitov, O V; Mourenas, D; Krasnoselskikh, V V; Mozer, F S

    2015-01-01

    .... Here, we report an analysis of 10-year Cluster data, statistically evaluating the full wave energy budget in the Earth's magnetosphere, revealing that a significant fraction of the energy corresponds...

  19. Magnetospheric Multiscale observations of large-amplitude, parallel, electrostatic waves associated with magnetic reconnection at the magnetopause

    Science.gov (United States)

    Ergun, R. E.; Holmes, J. C.; Goodrich, K. A.; Wilder, F. D.; Stawarz, J. E.; Eriksson, S.; Newman, D. L.; Schwartz, S. J.; Goldman, M. V.; Sturner, A. P.; Malaspina, D. M.; Usanova, M. E.; Torbert, R. B.; Argall, M.; Lindqvist, P.-A.; Khotyaintsev, Y.; Burch, J. L.; Strangeway, R. J.; Russell, C. T.; Pollock, C. J.; Giles, B. L.; Dorelli, J. J. C.; Avanov, L.; Hesse, M.; Chen, L. J.; Lavraud, B.; Le Contel, O.; Retino, A.; Phan, T. D.; Eastwood, J. P.; Oieroset, M.; Drake, J.; Shay, M. A.; Cassak, P. A.; Nakamura, R.; Zhou, M.; Ashour-Abdalla, M.; André, M.

    2016-06-01

    We report observations from the Magnetospheric Multiscale satellites of large-amplitude, parallel, electrostatic waves associated with magnetic reconnection at the Earth's magnetopause. The observed waves have parallel electric fields (E||) with amplitudes on the order of 100 mV/m and display nonlinear characteristics that suggest a possible net E||. These waves are observed within the ion diffusion region and adjacent to (within several electron skin depths) the electron diffusion region. They are in or near the magnetosphere side current layer. Simulation results support that the strong electrostatic linear and nonlinear wave activities appear to be driven by a two stream instability, which is a consequence of mixing cold (plasma in the magnetosphere with warm (~100 eV) plasma from the magnetosheath on a freshly reconnected magnetic field line. The frequent observation of these waves suggests that cold plasma is often present near the magnetopause.

  20. The Magnetospheres of (Accreting Neutron Stars

    Directory of Open Access Journals (Sweden)

    Wilms J.

    2014-01-01

    Full Text Available I give an overview of the most important observational tools to study the magnetospheres of accreting neutron stars, with a focus on accreting neutron stars in high mass X-ray binary systems. Topics covered are the different types of accretion onto neutron stars and the structure of the accretion column, and how models for these can be tested with observations.

  1. The Magnetospheric Boundary in Cataclysmic Variables

    Directory of Open Access Journals (Sweden)

    Hellier Coel

    2014-01-01

    During outbursts, when the accretion flow increases by orders of magnitude, the disk pushes the magnetosphere inwards, and appears to feed field lines over a much greater range of magnetic azimuth. The non-equilibrium outburst behaviour shows an even richer phenomenology than in quiescence, adding DNOs and QPOs into the mix.

  2. Impact of Solar Wind Depression on the Dayside Magnetosphere under Northward Interplanetary Magnetic Field

    CERN Document Server

    Baraka, Suleiman

    2010-01-01

    We present a follow up study of the sensitivity of the Earth's magnetosphere to solar wind activity using a particles-in-cell model [Baraka and Ben Jaffel, 2007], but here during northward IMF. The formation of the magnetospheric cavity and its elongation is obtained with the classical structure of a magnetosphere with parallel lobes. An impulsive disturbance is then applied to the system by changing the bulk velocity of the solar wind to simulate a decrease in the solar wind dynamic pressure followed by its recovery. In response to the imposed disturbance, a gap [abrupt depression] in the incoming solar wind plasma appears moving toward the Earth. The gap's size is a ~15 RE and is comparable to the sizes previously obtained for both Bz<0 and Bz =0. During the initial phase of the disturbance, the dayside magnetopause (MP) expands slower than the previous cases of IMF orientations as a result of the depression. The size of the MP expands nonlinearly due to strengthening of its outer boundary by the northwa...

  3. Magnetospheric Magnetic Reconnection with Southward IMF by a 3D EMPM Simulation

    Science.gov (United States)

    Nishikawa, K.-I.; Yan, X. Y.; Cai, D. S.; Lembege, B.

    2004-01-01

    We report our new simulation results on magnetospheric magnetic reconnection with southward IMF using a 3D EMPM model, with greater resolution and more particles using the parallelized 3D HPF TRISTAN code on VPP5000 supercomputer. Main parameters used in the new simulation are: domain size is 215 x 145 x 145, grid size = 0.5 Earth radius, initial particle number is 16 per cell, the IMF is southward. Arrival of southward IMF will cause reconnection in the magnetopause, thus allowing particles to enter into the inner magnetosphere. Sunward and tailward high particle flow are observed by satellites, and these phenomena are also observed in the simulation near the neutral line (X line) of the near-Earth magnetotail. This high particle flow goes along with the reconnected island. The magnetic reconnection process contributes to direct plasma entry between the magnetosheath to the inner magnetosphere and plasma sheet, in which the entry process eats the magnetosheath plasma to plasma sheet temperatures. We investigate magnetic, electric fields, density, and current during this magnetic reconnection with southward IMF. Further investigation with this simulation will provide insight into unsolved problems, such as the triggering of storms and substorms, and the storm-substorm relationship. New results will be presented at the meeting.

  4. Magnetospheric Whistler Mode Ray Tracing with the Inclusion of Finite Electron and Ion Temperature

    Science.gov (United States)

    Maxworth, A. S.; Golkowski, M.

    2015-12-01

    Ray tracing is an important technique for the study of whistler mode wave propagation in the Earth's magnetosphere. In numerical ray tracing the trajectory of a wave packet is calculated at each point in space by solving the Haselgrove equations, assuming a smooth, loss-less medium with no mode coupling. Previous work on ray tracing has assumed a cold plasma environment with negligible electron and ion temperatures. In this work we present magnetospheric whistler mode wave ray tracing results with the inclusion of finite ion and electron temperature. The inclusion of finite temperature effects makes the fourth order dispersion relation become sixth order. We compare our results with the work done by previous researchers for cold plasma environments, using two near earth space models (NGO and GCPM). Inclusion of finite temperature closes the otherwise open refractive index surface near the lower hybrid resonance frequency and affects the magnetospheric reflection of whistler waves. We also asses the main changes in the ray trajectory and implications for cyclotron resonance wave particle interactions including energetic particle precipitation.

  5. A statistical study of plasmawaves and energetic particles in the outer magnetosphere

    Science.gov (United States)

    Min, Kyungguk

    The Earth magnetosphere contains energetic particles undergoing specific motions around Earth's magnetic field, and interacting with a variety of waves. The dynamics of energetic particles are often described in terms of three kinds of adiabatic invariants. Energetic electrons are often unstable to the whistler-mode chorus waves, and ions, to the electromagnetic ion cyclotron (EMIC) instability. These waves play an important role in the dynamics of the magnetosphere by energizing electrons to form a radiation belt, extracting energy from the hot, anisotropic ions and causing pitch angle scattering of energetic ions and relativistic electrons into the loss cone. EMIC waves correspond to the highest frequency waves in the ultra-low frequency (ULF) spectral regime, and field line resonances at the lower frequency may serve as diagnostics for the plasma distribution in the magnetosphere. This dissertation investigates (1) a rapid, efficient way of specifying particle's adiabatic motion in the magnetosphere, (2) source of the whistler-mode chorus waves, (3) physical properties and coherent spatial dimensions of the EMIC waves and (4) a diagnostic use of the toroidal mode Alfven waves on the plasma density distribution in the Earth magnetosphere. The studies presented in this dissertation have significantly been benefited from the comprehensive data obtained by several space missions, including the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft, Cluster mission, the Geostationary Operational Environment Satellites (GOES), Los Alamos National Laboratory (LANL) satellites, the Polar spacecraft and the Active Magnetospheric Particle Tracer Explorers (AMPTE)/Charge Composition Explorer (CCE), and from ground-based Automatic Geophysical Observatories (AGO). The main findings and achievements in this dissertation are as follows: (1) A method of rapidly and efficiently computing the magnetic drift invariant (L*) was developed. This new

  6. Particle Acceleration in Dissipative Pulsar Magnetospheres

    Science.gov (United States)

    Kazanas, Z.; Kalapotharakos, C.; Harding, A.; Contopoulos, I.

    2012-01-01

    Pulsar magnetospheres represent unipolar inductor-type electrical circuits at which an EM potential across the polar cap (due to the rotation of their magnetic field) drives currents that run in and out of the polar cap and close at infinity. An estimate ofthe magnitude of this current can be obtained by dividing the potential induced across the polar cap V approx = B(sub O) R(sub O)(Omega R(sub O)/c)(exp 2) by the impedance of free space Z approx eq 4 pi/c; the resulting polar cap current density is close to $n {GJ} c$ where $n_{GJ}$ is the Goldreich-Julian (GJ) charge density. This argument suggests that even at current densities close to the GJ one, pulsar magnetospheres have a significant component of electric field $E_{parallel}$, parallel to the magnetic field, a condition necessary for particle acceleration and the production of radiation. We present the magnetic and electric field structures as well as the currents, charge densities, spin down rates and potential drops along the magnetic field lines of pulsar magnetospheres which do not obey the ideal MHD condition $E cdot B = 0$. By relating the current density along the poloidal field lines to the parallel electric field via a kind of Ohm's law $J = sigma E_{parallel}$ we study the structure of these magnetospheres as a function of the conductivity $sigma$. We find that for $sigma gg OmegaS the solution tends to the (ideal) Force-Free one and to the Vacuum one for $sigma 11 OmegaS. Finally, we present dissipative magnetospheric solutions with spatially variable $sigma$ that supports various microphysical properties and are compatible with the observations.

  7. Applications to particle transport in the Earth`s aurora

    Energy Technology Data Exchange (ETDEWEB)

    Jasperse, J.R.

    1994-12-31

    The visual display of light called the aurora borealis occurs when energetic (1 to 100-keV) electrons, protons, and hydrogen atoms from the Earth`s magnetosphere enter the Earth`s upper atmosphere and collide with the ambient neutral particles. Two kinds of auroras occur in nature: those excited by incident electrons and those excited by incident protons and hydrogen atoms. In this paper, we consider only the latter. The proton-hydrogen aurora may be divided into two altitude regions: high altitudes ({approximately}250 to {approximately}600 km) where charge-changing collisions dominate and energy-loss collisions may be neglected and low altitudes ({approximately}100 to {approximately}250 km) where energy-loss collisions also become important and cause rapid energy degradation. The focus of this review is on the high-altitude region where the one-group approximation is valid.

  8. Study of the solar wind-magnetosphere coupling on different time scales

    CERN Document Server

    Badruddin,

    2013-01-01

    Solar wind-magnetosphere coupling, its causes and consequences have been studied for the last several decades. However, the assessment of continuously changing behaviour of the sun, plasma and field flows in the interplanetary space and their influence on geomagnetic activity is still a subject of intense research. Search for the best possible coupling function is also important for space weather prediction. We utilize four geomagnetic indices (ap, aa, AE and Dst) as parameters of geomagnetic activity level in the earth's magnetosphere. In addition to these indices, we utilize various solar wind plasma and field parameters for the corresponding periods. We analyse the geomagnetic activity and plasma/field parameters at yearly, half-yearly, 27-day, daily, 3-hourly, and hourly time resolutions. Regression analysis using geomagnetic and solar wind data of different time resolutions, over a continuous long period, and at different phases of solar activity (increasing including maximum/decreasing including minimum...

  9. Weak Turbulence in the Magnetosphere: Formation of Whistler Wave Cavity by Nonlinear Scattering

    CERN Document Server

    Crabtree, C; Ganguli, G; Mithaiwala, M; Galinsky, V; Shevchenko, V

    2011-01-01

    We consider the weak turbulence of whistler waves in the in low-\\beta\\ inner magnetosphere of the Earth. Whistler waves with frequencies, originating in the ionosphere, propagate radially outward and can trigger nonlinear induced scattering by thermal electrons provided the wave energy density is large enough. Nonlinear scattering can substantially change the direction of the wave vector of whistler waves and hence the direction of energy flux with only a small change in the frequency. A portion of whistler waves return to the ionosphere with a smaller perpendicular wave vector resulting in diminished linear damping and enhanced ability to pitch-angle scatter trapped electrons. In addition, a portion of the scattered wave packets can be reflected near the ionosphere back into the magnetosphere. Through multiple nonlinear scatterings and ionospheric reflections a long-lived wave cavity containing turbulent whistler waves can be formed with the appropriate properties to efficiently pitch-angle scatter trapped e...

  10. Challenges Handling Magnetospheric and Ionospheric Signals in Internal Geomagnetic Field Modelling

    DEFF Research Database (Denmark)

    Finlay, Chris; Lesur, V.; Thébault, E.;

    2016-01-01

    -by-track analysis to characterize magnetospheric field fluctuations, differences in internal field models that result from alternative treatments of the quiet-time ionospheric field, and challenges associated with rapidly changing, but spatially correlated, magnetic signatures of polar cap current systems. Possible......Measurements of the Earth’s magnetic field collected by low-Earth-orbit satellites such as Swarm and CHAMP, as well as at ground observatories, are dominated by sources in the Earth’s interior. However these measurements also contain significant contributions from more rapidly-varying current...... systems in the ionosphere and magnetosphere. In order to fully exploit magnetic data to probe the physical properties and dynamics of the Earth’s interior, field models with suitable treatments of external sources, and their associated induced signals, are essential. Here we review the methods presently...

  11. Magnetospherically driven optical and radio aurorae at the end of the stellar main sequence

    CERN Document Server

    Hallinan, G; Cotter, G; Bourke, S; Harding, L K; Pineda, J S; Butler, R P; Golden, A; Basri, G; Doyle, J G; Kao, M M; Berdyugina, S V; Kuznetsov, A; Rupen, M P; Antonova, A

    2015-01-01

    Aurorae are detected from all the magnetized planets in our Solar System, including Earth. They are powered by magnetospheric current systems that lead to the precipitation of energetic electrons into the high-latitude regions of the upper atmosphere. In the case of the gas-giant planets, these aurorae include highly polarized radio emission at kilohertz and megahertz frequencies produced by the precipitating electrons, as well as continuum and line emission in the infrared, optical, ultraviolet and X-ray parts of the spectrum, associated with the collisional excitation and heating of the hydrogen-dominated atmosphere. Here we report simultaneous radio and optical spectroscopic observations of an object at the end of the stellar main sequence, located right at the boundary between stars and brown dwarfs, from which we have detected radio and optical auroral emissions both powered by magnetospheric currents. Whereas the magnetic activity of stars like our Sun is powered by processes that occur in their lower a...

  12. On plasma convection in Saturn's magnetosphere

    Science.gov (United States)

    Livi, Roberto

    We use CAPS plasma data to derive particle characteristics within Saturn's inner magnetosphere. Our approach is to first develop a forward-modeling program to derive 1-dimensional (1D) isotropic plasma characteristics in Saturn's inner, equatorial magnetosphere using a novel correction for the spacecraft potential and penetrating background radiation. The advantage of this fitting routine is the simultaneous modeling of plasma data and systematic errors when operating on large data sets, which greatly reduces the computation time and accurately quantifies instrument noise. The data set consists of particle measurements from the Electron Spectrometer (ELS) and the Ion Mass Spectrometer (IMS), which are part of the Cassini Plasma Spectrometer (CAPS) instrument suite onboard the Cassini spacecraft. The data is limited to peak ion flux measurements within +/-10° magnetic latitude and 3-15 geocentric equatorial radial distance (RS). Systematic errors such as spacecraft charging and penetrating background radiation are parametrized individually in the modeling and are automatically addressed during the fitting procedure. The resulting values are in turn used as cross-calibration between IMS and ELS, where we show a significant improvement in magnetospheric electron densities and minor changes in the ion characteristics due to the error adjustments. Preliminary results show ion and electron densities in close agreement, consistent with charge neutrality throughout Saturn's inner magnetosphere and confirming the spacecraft potential to be a common influence on IMS and ELS. Comparison of derived plasma parameters with results from previous studies using CAPS data and the Radio And Plasma Wave Science (RPWS) investigation yields good agreement. Using the derived plasma characteristics we focus on the radial transport of hot electrons. We present evidence of loss-free adiabatic transport of equatorially mirroring electrons (100 eV - 10 keV) in Saturn's magnetosphere between

  13. Magnetospheric Multiscale (MMS) Mission Commissioning Phase Orbit Determination Error Analysis

    Science.gov (United States)

    Chung, Lauren R.; Novak, Stefan; Long, Anne; Gramling, Cheryl

    2009-01-01

    The Magnetospheric MultiScale (MMS) mission commissioning phase starts in a 185 km altitude x 12 Earth radii (RE) injection orbit and lasts until the Phase 1 mission orbits and orientation to the Earth-Sun li ne are achieved. During a limited time period in the early part of co mmissioning, five maneuvers are performed to raise the perigee radius to 1.2 R E, with a maneuver every other apogee. The current baseline is for the Goddard Space Flight Center Flight Dynamics Facility to p rovide MMS orbit determination support during the early commissioning phase using all available two-way range and Doppler tracking from bo th the Deep Space Network and Space Network. This paper summarizes th e results from a linear covariance analysis to determine the type and amount of tracking data required to accurately estimate the spacecraf t state, plan each perigee raising maneuver, and support thruster cal ibration during this phase. The primary focus of this study is the na vigation accuracy required to plan the first and the final perigee ra ising maneuvers. Absolute and relative position and velocity error hi stories are generated for all cases and summarized in terms of the ma ximum root-sum-square consider and measurement noise error contributi ons over the definitive and predictive arcs and at discrete times inc luding the maneuver planning and execution times. Details of the meth odology, orbital characteristics, maneuver timeline, error models, and error sensitivities are provided.

  14. Large-Scale Structure of Magnetospheric Plasma

    Science.gov (United States)

    Moore, T. E.; Delcourt, D. C.

    1995-01-01

    Recent investigations of magnetospheric plasma structure are summarized under the broad categories of empirical models, transport across boundaries, formation, and dynamics of the plasma sheet. This report reviews work in these areas during the period 1991 to 1993. Fully three-dimensional empirical models and simulations have become important contributors to our understanding of the magnetospheric system. Some new structural concepts have appeared in the literature: the 'entry boundary' and 'geo-pause', the plasma sheet 'region 1 vortices', the 'low-energy layer', the 'adia-baticity boundary' or 'wall region', and a region in the tail to which we refer as the 'injection port'. Traditional structural concepts have also been the subject of recent study, notably the plasmapause, the magnetopause, and the plasma sheet. Significant progress has been made in understanding the nature of plasma sheet formation and dynamics, but the acceleration of electrons to high energy remains somewhat mysterious.

  15. General relativistic neutron stars with twisted magnetosphere

    CERN Document Server

    Pili, A G; Del Zanna, L

    2014-01-01

    Soft Gamma-Ray Repeaters and Anomalous X-Ray Pulsars are extreme manifestations of the most magnetized neutron stars: magnetars. The phenomenology of their emission and spectral properties strongly support the idea that the magnetospheres of these astrophysical objects are tightly twisted in the vicinity of the star. Previous studies on equilibrium configurations have so far focused on either the internal or the external magnetic field configuration, without considering a real coupling between the two fields. Here we investigate numerical equilibrium models of magnetized neutron stars endowed with a confined twisted magnetosphere, solving the general relativistic Grad-Shafranov equation both in the interior and in the exterior of the compact object. A comprehensive study of the parameters space is provided to investigate the effects of different current distributions on the overall magnetic field structure.

  16. Electromagnetic Quantities in Black Hole Magnetosphere

    Institute of Scientific and Technical Information of China (English)

    汪定雄; 马任意; 雷卫华; 姚国政

    2004-01-01

    Some electromagnetic quantities in the black hole (BH) magnetosphere are discussed by considering the coexistence of the Blandford-Znajek process and the magnetic coupling process. These quantities are (i) flux of electromagnetic energy and angular momentum transferred between the BH and the disc, (ii) poloidal currents flowing on the horizon and disc, (iii) poloidal electric field on the horizon, (iv) toroidal magnetic field in the BH magnetosphere,and (v) voltage drop across the magnetic coupling region on the horizon. It turns out that these quantities are determined mainly by three parameters: (i) the positions relative to the corotation magnetic surface, (ii) the BH spin, and (iii) the power-law index for the variation of the magnetic field on the disc.

  17. Laboratory simulation of magnetospheric chorus wave generation

    Science.gov (United States)

    Van Compernolle, B.; An, X.; Bortnik, J.; Thorne, R. M.; Pribyl, P.; Gekelman, W.

    2017-01-01

    Whistler mode chorus emissions with a characteristic frequency chirp are important magnetospheric waves, responsible for the acceleration of outer radiation belt electrons to relativistic energies and also for the scattering loss of these electrons into the atmosphere. A laboratory experiment (Van Compernolle et al 2015 Phys. Rev. Lett. 114 245002, An et al 2016 Geophys. Res. Lett.) in the large plasma device at UCLA was designed to closely mimic the scaled plasma parameters observed in the inner magnetosphere, and shed light on the excitation of discrete frequency whistler waves. It was observed that a rich variety of whistler wave emissions is excited by a gyrating electron beam. The properties of the whistler emissions depend strongly on plasma density, beam density and magnetic field profiles.

  18. Testing the SOC hypothesis for the magnetosphere

    CERN Document Server

    Watkins, N W; Chapman, S C; Dendy, R O

    2001-01-01

    As noted by Chang, the hypothesis of Self-Organised Criticality provides atheoretical framework in which the low dimensionality seen in magnetosphericindices can be combined with the scaling seen in their power spectra and therecently-observed plasma bursty bulk flows. As such, it has considerableappeal, describing the aspects of the magnetospheric fuelling:storage:releasecycle which are generic to slowly-driven, interaction-dominated, thresholdedsystems rather than unique to the magnetosphere. In consequence, several recentnumerical "sandpile" algorithms have been used with a view to comparison withmagnetospheric observables. However, demonstration of SOC in the magnetospherewill require further work in the definition of a set of observable propertieswhich are the unique "fingerprint" of SOC. This is because, for example, ascale-free power spectrum admits several possible explanations other than SOC. A more subtle problem is important for both simulations and data analysiswhen dealing with multiscale and hen...

  19. Extremely efficient Zevatron in rotating AGN magnetospheres

    CERN Document Server

    Osmanov, Zaza; Machabeli, George; Chkheidze, Nino

    2014-01-01

    A novel model of particle acceleration in the magnetospheres of rotating Active Galactic Nuclei (AGN) is constructed.The particle energies may be boosted up to 10^{21}eV in a two step mechanism: In the first stage, the Langmuir waves are centrifugally excited and amplified by means of a parametric process that efficiently pumps rotational energy to excite electrostatic fields. In the second stage, the electrostatic energy is transferred to particle kinetic energy via Landau damping made possible by rapid "Langmuir collapse". The time scale for parametric pumping of Langmuir waves turns out to be small compared to the kinematic timescale, indicating high efficiency of the first process. The second process of "Langmuir collapse" - the creation of caverns or low density regions - also happens rapidly for the characteristic parameters of the AGN magnetosphere. The Langmuir collapse creates appropriate conditions for transferring electric energy to boost up already high particle energies to much higher values. It ...

  20. Pulsar Magnetospheres: Beyond the Flat Spacetime Dipole

    CERN Document Server

    Gralla, Samuel E; Philippov, Alexander

    2016-01-01

    Most studies of the pulsar magnetosphere have assumed a pure magnetic dipole in flat spacetime. However, recent work suggests that the effects of general relativity are in fact of vital importance and that realistic pulsar magnetic fields may have a significant nondipolar component. We introduce a general analytical method for studying the axisymmetric force-free magnetosphere of a slowly-rotating star of arbitrary magnetic field, mass, radius and moment of inertia, including all the effects of general relativity. We confirm that spacelike current is generically present in the polar caps (suggesting a pair production region), irrespective of the stellar magnetic field. We show that general relativity introduces a ~60% correction to the formula for the dipolar component of the surface magnetic field inferred from spindown. Finally, we show that the location and size of the polar caps can be modified dramatically by even modestly strong higher moments. This can affect emission processes occurring near the star ...

  1. Mercury's Magnetospheric Cusps and Cross-Tail Current Sheet: Structure and Dynamics

    Science.gov (United States)

    Poh, Gang Kai

    Mercury has proven to be a unique natural laboratory for space plasma processes. Mercury's magnetosphere is formed by the interaction between its intrinsic planetary magnetic field and the supersonic solar wind. The structure of Mercury's magnetosphere is very similar to Earth's; yet the results from the MESSENGER mission to Mercury have shown that the spatial and temporal scales of magnetospheric processes are very different at Mercury. In this thesis, we analyze in situ observations from the MESSENGER spacecraft to characterize and understand the dynamic physical plasma processes occurring in Mercury's magnetosphere. We identified and analyzed 345 plasma filaments in Mercury's northern magnetospheric cusp to determine their physical properties. Cusp plasma filaments are magnetic structures that are identified on the basis of their characteristic 2-3 seconds long decrease in magnetic field intensity. Our analysis indicates that these cusp filaments are cylindrical flux tubes filled with plasma, which causes a diamagnetic decrease in the magnetic field inside the flux tube. MESSENGER observations of flux transfer events (FTEs) and cusp filament suggests that cusp filaments properties are the low-altitude extension of FTEs formed at Mercury's dayside magnetopause. We examined 319 central plasma sheet crossings observed by MESSENGER. Using a Harris model, we determined the physical properties of Mercury's cross-tail current sheet. Analysis of BZ in the current sheet indicated that MESSENGER usually crossed the current sheet sunward of the Near Mercury Neutral Line. Magnetohydrodynamics-based analysis using the MESSENGER magnetic field and plasma measurements suggests that heavy planetary ions and/or ion temperature anisotropy may be important in maintaining radial stress balance within Mercury's central plasma sheet. We report the observation of significant dawn-dusk variation in Mercury's cross-tail current sheet with thicker, lower plasma beta dawn side current

  2. Solar wind-magnetosphere energy input functions

    Energy Technology Data Exchange (ETDEWEB)

    Bargatze, L.F.; McPherron, R.L.; Baker, D.N.

    1985-01-01

    A new formula for the solar wind-magnetosphere energy input parameter, P/sub i/, is sought by applying the constraints imposed by dimensional analysis. Applying these constraints yields a general equation for P/sub i/ which is equal to rho V/sup 3/l/sub CF//sup 2/F(M/sub A/,theta) where, rho V/sup 3/ is the solar wind kinetic energy density and l/sub CF//sup 2/ is the scale size of the magnetosphere's effective energy ''collection'' region. The function F which depends on M/sub A/, the Alfven Mach number, and on theta, the interplanetary magnetic field clock angle is included in the general equation for P/sub i/ in order to model the magnetohydrodynamic processes which are responsible for solar wind-magnetosphere energy transfer. By assuming the form of the function F, it is possible to further constrain the formula for P/sub i/. This is accomplished by using solar wind data, geomagnetic activity indices, and simple statistical methods. It is found that P/sub i/ is proportional to (rho V/sup 2/)/sup 1/6/VBG(theta) where, rho V/sup 2/ is the solar wind dynamic pressure and VBG(theta) is a rectified version of the solar wind motional electric field. Furthermore, it is found that G(theta), the gating function which modulates the energy input to the magnetosphere, is well represented by a ''leaky'' rectifier function such as sin/sup 4/(theta/2). This function allows for enhanced energy input when the interplanetary magnetic field is oriented southward. This function also allows for some energy input when the interplanetary magnetic field is oriented northward. 9 refs., 4 figs.

  3. Terrestrial VLF transmitter injection into the magnetosphere

    OpenAIRE

    2012-01-01

    Terrestrial VLF transmitter injection into the magnetosphere M. B. Cohen1 and U. S. Inan1,2 Received 1 June 2012; revised 15 June 2012; accepted 18 June 2012; published 9 August 2012. [1] Very Low Frequency (VLF, 3–30 kHz) radio waves emitted from ground sources (transmitters and lightning) strongly impact the radiation belts, driving electron precipitation via whistler-electron gyroresonance, and contributing to the formation of the slot region. However, calculations of the...

  4. Energy-banded ions in Saturn's magnetosphere

    Science.gov (United States)

    Thomsen, M. F.; Badman, S. V.; Jackman, C. M.; Jia, X.; Kivelson, M. G.; Kurth, W. S.

    2017-05-01

    Using data from the Cassini Plasma Spectrometer ion mass spectrometer, we report the first observation of energy-banded ions at Saturn. Observed near midnight at relatively high magnetic latitudes, the banded ions are dominantly H+, and they occupy the range of energies typically associated with the thermal pickup distribution in the inner magnetosphere (L distance (or time or decreasing latitude). Their pitch angle distribution suggests a source at low (or slightly southern) latitudes. The band energies, including their pitch angle dependence, are consistent with a bounce-resonant interaction between thermal H+ ions and the standing wave structure of a field line resonance. There is additional evidence in the pitch angle dependence of the band energies that the particles in each band may have a common time of flight from their most recent interaction with the wave, which may have been at slightly southern latitudes. Thus, while the particles are basically bounce resonant, their energization may be dominated by their most recent encounter with the standing wave.Plain Language SummaryDuring an outbound passage by the Cassini spacecraft through Saturn's inner magnetosphere, ion energy distributions were observed that featured discrete flux peaks at regularly spaced energies. The peaks persisted over several hours and several Saturn radii of distance away from the planet. We show that these "bands" of ions are plausibly the result of an interaction between the Saturnian plasma and standing waves that form along the magnetospheric magnetic field lines. These observations are the first reported evidence that such standing waves may be present in the inner magnetosphere, where they could contribute to the radial transport of Saturn's radiation belt particles.

  5. The Virtual Magnetospheric Observatory at UCLA

    Science.gov (United States)

    Walker, R. J.; King, T. A.; Joy, S. P.; Bargatze, L. F.; Chi, P.; Weygand, J.

    2007-12-01

    The Virtual Magnetospheric Observatory (VMO) creates robust links to the world's relevant data bases and thereby provides one-stop shopping for the magnetospheric researcher seeking data. The VMO is a joint effort of scientists at the Goddard Space Flight Center (GSFC) and UCLA. The VMO supports two ways for a scientist to find the data and access the data needed for a given study. One is a structured interface developed at GSFC and the other is a word based interface (Google like) developed at UCLA. Both interfaces provide well organized views of the diverse scientific data holdings needed for magnetospheric research. The word based interface will be demonstrated at the poster. Since data are dynamic, the VMO portal design allows frequent and asynchronous updating. The VMO will only succeed in serving the needs of the magnetospheric science community if most of the world's data repositories are part of the system. Therefore we have worked to make it simple to participate in the VMO. The registries for both data and services are designed to make it easy for suppliers to make their resources available and update information. The basis for resource descriptions is the SPASE data model. We have created tools to enable data repositories to populate the registries and to communicate with the VMO even if they use other data models. Scientists trained in data management, called domain experts, are available to work with data suppliers to prepare the metadata and to create archival quality data products. We describe how the domain experts bring information into the VMO.

  6. Dynamic boundaries of event horizon magnetospheres

    Science.gov (United States)

    Punsly, Brian

    2007-10-01

    This Letter analyses three-dimensional (3D) simulations of Kerr black hole magnetospheres that obey the general relativistic equations of perfect magnetohydrodynamics (MHD). Particular emphasis is on the event horizon magnetosphere (EHM) which is defined as the the large-scale poloidal magnetic flux that threads the event horizon of a black hole. (This is distinct from the poloidal magnetic flux that threads the equatorial plane of the ergosphere, which forms the ergospheric disc magnetosphere.) Standard MHD theoretical treatments of Poynting jets in the EHM are predicated on the assumption that the plasma comprising the boundaries of the EHM plays no role in producing the Poynting flux. The energy flux is electrodynamic in origin and it is essentially conserved from the horizon to infinity; this is known as the Blandford-Znajek (B-Z) mechanism. In contrast, within the 3D simulations, the lateral boundaries are strong pistons for MHD waves and actually inject prodigious quantities of Poynting flux into the EHM. At high black hole spin rates, strong sources of Poynting flux adjacent to the EHM from the ergospheric disc will actually diffuse to higher latitudes and swamp any putative B-Z effects. This is in contrast to lower spin rates, which are characterized by much lower output powers, and where modest amounts of Poynting flux are injected into the EHM from the accretion disc corona.

  7. Planetary Magnetosphere Probed by Charged Dust Particles

    Science.gov (United States)

    Sternovsky, Z.; Horanyi, M.; Gruen, E.; Srama, R.; Auer, S.; Kempf, S.; Krueger, H.

    2010-12-01

    In-situ and remote sensing observations combined with theoretical and numerical modeling greatly advanced our understanding planetary magnetospheres. Dust is an integral component of the Saturnian and Jovian magnetospheres where it can act as a source/sink of plasma particles (dust particles are an effective source for plasma species like O2, OH, etc. through sputtering of ice particles, for example); its distribution is shaped by electrodynamic forces coupled radiation pressure, plasma, and neutral drag, for example. The complex interaction can lead to unusual dust dynamics, including the transport, capture, and ejection of dust grains. The study of the temporal and spatial evolution of fine dust within or outside the magnetosphere thus provides a unique way to combine data from a large number of observations: plasma, plasma wave, dust, and magnetic field measurements. The dust detectors on board the Galileo and Cassini spacecrafts lead to major discoveries, including the jovian dust stream originating from Io or the in-situ sampling and analysis of the plumes of Enceladus. Recent advancement in dust detector technology enables accurate measurement of the dust trajectory and elemental composition that can greatly enhance the understanding of dust magnetorspheric interaction and indentify the source of the dust with high precision. The capabilities of a modern dust detector thus can provide support for the upcoming Europa Jupiter System Mission.

  8. The Magnetospheric Boundary in Cataclysmic Variables

    CERN Document Server

    Hellier, Coel

    2013-01-01

    The magnetic cataclysmic variables (MCVs) present a wealth of observational diagnostics for studying accretion flows interacting with a magnetosphere. Spin-period pulsations from the rotation of the white dwarf are seen in optical light, in the UV and X-ray bands, and in polarimetry, and modelling these can constrain the size and location of the accretion footprints on the white-dwarf surface. Tracing these back along field lines can tell us about the transition region between the stream or disk and the magnetosphere. Further, optical emission lines give us velocity information, while analysis of eclipses gives spatial information. I discuss MCVs (particularly FO Aqr, V405 Aur, XY Ari and EX Hya, but also mentioning PQ Gem, GK Per, V2400 Oph, HT Cam, TX Col, AO Psc, AE Aqr, WZ Sge, V1223 Sgr and DQ Her), reviewing what observations tell us about the disk-magnetosphere boundary. The spin-period variations are caused by a mixture of geometric effects and absorption by the accretion flow, and appear to show that...

  9. On the origin of high m magnetospheric waves

    OpenAIRE

    Beharrell, Matthew J.; Kavanagh, Andrew J.; F. Honary

    2010-01-01

    A survey of Advanced Rio-Imaging Experiment in Scandinavia data reveals evidence for a previously overlooked generation mechanism of high azimuthal wave number magnetospheric waves. Here we present observations of pulsating cosmic noise absorption with azimuthal wave numbers as high as 380, suggestive of precipitation modulation by magnetospheric waves. Dispersion relations of the small-scale precipitation pulsations are indicative of the proposed origin. Previous studies of magnetospheric wa...

  10. Recent Progresses of Magnetospheric Physics in China: 2010-2011

    Institute of Scientific and Technical Information of China (English)

    CAO Jinbin; LIU Zhenxing; PU Zuyin

    2012-01-01

    In the past two years, many progresses are made in magnetospheric physics by using either the data of Double Star Program, Cluster and THEMIS missions, or by computer simulations. This paper briefly reviews these works based on papers selected from the 80 publications from April 2010 to April 2011. The subjects covered various sub-branches of magnetospheric physics, including geomagnetic storm, magnetospheric substorm, etc.

  11. Improvement of magnetosphere structure calculations using eccentric dipole to account for the internal magnetic field

    Science.gov (United States)

    Parunakian, David

    2014-05-01

    In this paper we build upon the results previously produced by numerous attempts, including our own, to approximate the geomagnetic field with a an eccentric dipole instead of spherical harmonics expansions. Among other motivations to do so is that dipole-related effects are much more pronounced relative to higher-order harmonics at large distances from the Earth, and that the shift of the order of magnitude about 0.1 Earth radii is significant enough for many magnetospheric structures such as the current sheet. We present the results of multivariate simulated annealing, which includes translational and rotational repositioning of the dipole. We also include similar results produced for Mercury and Saturn, and we extend Earth-related data with Oersted and Cluster measurements in order to further improve our accuracy.

  12. Joint inversion of satellite-detected tidal and magnetospheric signals constrains electrical conductivity and water content of the upper mantle and transition zone

    DEFF Research Database (Denmark)

    Grayver, Alexander V.; Munch, F. D.; Kuvshinov, Alexey V.

    2017-01-01

    We present a new global electrical conductivity model of Earth's mantle. The model was derived by using a novel methodology, which is based on inverting satellite magnetic field measurements from different sources simultaneously. Specifically, we estimated responses of magnetospheric origin and o...

  13. Magnetorotational and Tayler Instabilities in the Pulsar Magnetosphere

    Indian Academy of Sciences (India)

    Vadim Urpin

    2017-09-01

    The magnetospheres around neutron stars should be very particular because of their strong magnetic field and rapid rotation. A study of the pulsar magnetospheres is of crucial importance since it is the key issue to understand how energy outflow to the exterior is produced. In this paper, we discuss magnetohydrodynamic processes in the pulsar magnetosphere. We consider in detail the properties of magnetohydrodynamic waves that can exist in the magnetosphere and their instabilities. These instabilities lead to formation of magnetic structures and can be responsible for short-term variability of the pulsar emission.

  14. On the occurrence of ground observations of ELF/VLF magnetospheric amplification induced by the HAARP facility

    OpenAIRE

    İnan, Umran Savaş; Golkowski, M.; Cohen, M. B.; Carpenter, D. L.

    2011-01-01

    The ionospheric heating facility of the High Frequency Active Auroral Research Program (HAARP) has been used extensively in the last 3 years for injection of ELF/VLF waves into the magnetosphere via modulated heating of the overhead auroral electrojet currents. Of particular interest are waves that are observed to be nonlinearly amplified after interaction with hot plasma electrons in the Earth's radiation belts. Past results have shown HAARP to be an effective platform for controlled studies...

  15. Ionosphere-magnetosphere energy interplay in the regions of diffuse aurora

    Science.gov (United States)

    Khazanov, G. V.; Glocer, A.; Sibeck, D. G.; Tripathi, A. K.; Detweiler, L. G.; Avanov, L. A.; Singhal, R. P.

    2016-07-01

    Both electron cyclotron harmonic (ECH) waves and whistler mode chorus waves resonate with electrons of the Earth's plasma sheet in the energy range from tens of eV to several keV and produce the electron diffuse aurora at ionospheric altitudes. Interaction of these superthermal electrons with the neutral atmosphere leads to the production of secondary electrons (E whistler mode chorus waves, however, can also interact with the secondary electrons that are coming from both of the magnetically conjugated ionospheres after they have been produced by initially precipitated high-energy electrons that came from the plasma sheet. After their degradation and subsequent reflection in magnetically conjugate atmospheric regions, both the secondary electrons and the precipitating electrons with high (E > 600 eV) initial energies will travel back through the loss cone, become trapped in the magnetosphere, and redistribute the energy content of the magnetosphere-ionosphere system. Thus, scattering of the secondary electrons by ECH and whistler mode chorus waves leads to an increase of the fraction of superthermal electron energy deposited into the core magnetospheric plasma.

  16. Spatial distribution of upstream magnetospheric ≥50 keV ions

    Directory of Open Access Journals (Sweden)

    G. Kaliabetsos

    Full Text Available We present for the first time a statistical study of geq50 keV ion events of a magnetospheric origin upstream from Earth's bow shock. The statistical analysis of the 50-220 keV ion events observed by the IMP-8 spacecraft shows: (1 a dawn-dusk asymmetry in ion distributions, with most events and lower intensities upstream from the quasi-parallel pre-dawn side (4 LT-6 LT of the bow shock, (2 highest ion fluxes upstream from the nose/dusk side of the bow shock under an almost radial interplanetary magnetic field (IMF configuration, and (3 a positive correlation of the ion intensities with the solar wind speed and the index of geomagnetic index Kp, with an average solar wind speed as high as 620 km s-1 and values of the index Kp > 2. The statistical results are consistent with (1 preferential leakage of ~50 keV magnetospheric ions from the dusk magnetopause, (2 nearly scatter free motion of ~50 keV ions within the magnetosheath, and (3 final escape of magnetospheric ions from the quasi-parallel dawn side of the bow shock. An additional statistical analysis of higher energy (290-500 keV upstream ion events also shows a dawn-dusk asymmetry in the occurrence frequency of these events, with the occurrence frequency ranging between ~16%-~34% in the upstream region.Key words. Interplanetary physics (energetic particles; planetary bow shocks

  17. Field Line Resonances in Quiet and Disturbed Time Three-dimensional Magnetospheres

    CERN Document Server

    Chi Zhu Cheng

    2002-01-01

    Numerical solutions for field line resonances (FLR) in the magnetosphere are presented for three-dimensional equilibrium magnetic fields represented by two Euler potentials as B = -j Y -a, where j is the poloidal flux and a is a toroidal angle-like variable. The linearized ideal-MHD equations for FLR harmonics of shear Alfvin waves and slow magnetosonic modes are solved for plasmas with the pressure assumed to be isotropic and constant along a field line. The coupling between the shear Alfvin waves and the slow magnetosonic waves is via the combined effects of geodesic magnetic field curvature and plasma pressure. Numerical solutions of the FLR equations are obtained for a quiet time magnetosphere as well as a disturbed time magnetosphere with a thin current sheet in the near-Earth region. The FLR frequency spectra in the equatorial plane as well as in the auroral latitude are presented. The field line length, magnetic field intensity, plasma beta, geodesic curvature and pressure gradient in the poloidal flux...

  18. Challenges in Measuring External Currents Driven by the Solar Wind-Magnetosphere Interaction

    Science.gov (United States)

    Le, Guan; Slavin, James A.; Pfaff, Robert F.

    2014-01-01

    In studying the Earth's geomagnetism, it has always been a challenge to separate magnetic fields from external currents originating from the ionosphere and magnetosphere. While the internal magnetic field changes very slowly in time scales of years and more, the ionospheric and magnetospheric current systems driven by the solar wind -magnetosphere interaction are very dynamic. They are intimately controlled by the ionospheric electrodynamics and ionospheremagnetosphere coupling. Single spacecraft observations are not able to separate their spatial and temporal variations, and thus to accurately describe their configurations. To characterize and understand the external currents, satellite observations require both good spatial and temporal resolutions. This paper reviews our observations of the external currents from two recent LEO satellite missions: Space Technology 5 (ST-5), NASA's first three-satellite constellation mission in LEO polar orbit, and Communications/Navigation Outage Forecasting System (C/NOFS), an equatorial satellite developed by US Air Force Research Laboratory. We present recommendations for future geomagnetism missions based on these observations.

  19. Magnetospheric energy inputs into the upper atmospheres of the giant planets

    Directory of Open Access Journals (Sweden)

    C. G. A. Smith

    2005-07-01

    Full Text Available We revisit the effects of Joule heating upon the upper atmospheres of Jupiter and Saturn. We show that in addition to direct Joule heating there is an additional input of kinetic energy – ion drag energy – which we quantify relative to the Joule heating. We also show that fluctuations about the mean electric field, as observed in the Earth's ionosphere, may significantly increase the Joule heating itself. For physically plausible parameters these effects may increase previous estimates of the upper atmospheric energy input at Saturn from ~10 TW to ~20 TW.

    Keywords. Ionosphere (Electric fields and currents; Planetary ionosphere – Magnetospheric physics (Auroral phenomena

  20. A method of evaluating quantitative magnetospheric field models by an angular parameter alpha

    Science.gov (United States)

    Sugiura, M.; Poros, D. J.

    1979-01-01

    The paper introduces an angular parameter, termed alpha, which represents the angular difference between the observed, or model, field and the internal model field. The study discusses why this parameter is chosen and demonstrates its usefulness by applying it to both observations and models. In certain areas alpha is more sensitive than delta-B (the difference between the magnitude of the observed magnetic field and that of the earth's internal field calculated from a spherical harmonic expansion) in expressing magnetospheric field distortions. It is recommended to use both alpha and delta-B in comparing models with observations.

  1. Sensitivity of Magnetospheric Multi-Scale (MMS) Mission Navigation Accuracy to Major Error Sources

    Science.gov (United States)

    Olson, Corwin; Long, Anne; Car[emter. Russell

    2011-01-01

    The Magnetospheric Multiscale (MMS) mission consists of four satellites flying in formation in highly elliptical orbits about the Earth, with a primary objective of studying magnetic reconnection. The baseline navigation concept is independent estimation of each spacecraft state using GPS pseudorange measurements referenced to an Ultra Stable Oscillator (USO) with accelerometer measurements included during maneuvers. MMS state estimation is performed onboard each spacecraft using the Goddard Enhanced Onboard Navigation System (GEONS), which is embedded in the Navigator GPS receiver. This paper describes the sensitivity of MMS navigation performance to two major error sources: USO clock errors and thrust acceleration knowledge errors.

  2. Magnetosphere Magnetic Field Wobble Effects on the Dynamics of the Jovian Magnetosphere

    CERN Document Server

    Winglee, Robert M

    2016-01-01

    The Jovian magnetosphere is complicated by the multiple plasma sources and ion species present within it, as well as fast rotation with its dipole axis titled from its rotational axis. To date global models of Jovian have neglected the presence of the different ion species as well as the tilted nature of the dipole axis. This paper reports the results of the first multi-fluid global modeling of these effects in a single self-consistent study for processes occurring in the outer magnetosphere. In the inner magnetosphere the model densities are shown to be comparable to observed densities with much of the density variables due to the wobble. The wobble enables plasma to be transported to higher latitudes and then centrifugal acceleration leads to radial transport of the plasma. At the interface between the middle and outer magnetosphere, the wobble produces a sinusoidal modulation of the plasma properties, which yields at a fixed observing point two density peaks, each with the planetary period. However, becaus...

  3. Cassini/MIMI Measurements in Saturn's Magnetosphere and their Implications for Magnetospheric Dynamics

    Science.gov (United States)

    Mitchell, D. G.

    2016-12-01

    The Cassini spacecraft has been in orbit about Saturn since early July, 2004. In less than a year, on September 15, 2017, Cassini will plunge into Saturn's atmosphere, ending what has been a highly successful and interesting mission. As befitting a Planetary Division Flagship Mission, Cassini's science payload included instrumentation designed for a multitude of science objectives, from surfaces of moons to rings to atmospheres to Saturn's vast, fast-rotating magnetosphere. Saturn's magnetosphere exhibits considerable variability, both from inner magnetosphere to outer, and over time. Characterizing the dynamics of the magnetosphere has required the full range of energetic particles (measured by the magnetospheric imaging instrument, MIMI - https://saturn.jpl.nasa.gov/magnetospheric-imaging-instrument/), plasma (provided by the Cassini plasma spectrometer, CAPS), gas (ion and neutral mass spectrometer, INMS), magnetic fields (Cassini magnetometer, MAG), radio and plasma waves (radio and plasma wave science, RPWS), dust (Cassini Dust Analyzer, CDA), as well as ultraviolet, visible and infrared imaging (ultraviolet imaging spectrograph, UVIS; Cassini imaging subsystem ISS; visible and infrared mapping spectrometer, VIMS; Cassini composite infrared spectrometer, CIRS) and ionospheric sounding by the Cassini radio science subsystem (RSS). It has also required the full range of orbital geometries from equatorial to high inclination and all local times, as well as the full range of solar wind conditions, seasonal sun-Saturn configurations. In this talk we focus on the contributions of the MIMI instrument suite (CHEMS, LEMMS, and INCA) to our understanding of the dynamics of Saturn's magnetosphere. We will both review past work, and present recent observations from the high inclination orbits that precede the final stages of the Cassini mission, the sets of high inclination orbits that cross the equator just beyond the edge of the main ring system, and later cross between

  4. Global MHD simulations of Neptune's magnetosphere

    Science.gov (United States)

    Mejnertsen, L.; Eastwood, J. P.; Chittenden, J. P.; Masters, A.

    2016-08-01

    A global magnetohydrodynamic (MHD) simulation has been performed in order to investigate the outer boundaries of Neptune's magnetosphere at the time of Voyager 2's flyby in 1989 and to better understand the dynamics of magnetospheres formed by highly inclined planetary dipoles. Using the MHD code Gorgon, we have implemented a precessing dipole to mimic Neptune's tilted magnetic field and rotation axes. By using the solar wind parameters measured by Voyager 2, the simulation is verified by finding good agreement with Voyager 2 magnetometer observations. Overall, there is a large-scale reconfiguration of magnetic topology and plasma distribution. During the "pole-on" magnetospheric configuration, there only exists one tail current sheet, contained between a rarefied lobe region which extends outward from the dayside cusp, and a lobe region attached to the nightside cusp. It is found that the tail current always closes to the magnetopause current system, rather than closing in on itself, as suggested by other models. The bow shock position and shape is found to be dependent on Neptune's daily rotation, with maximum standoff being during the pole-on case. Reconnection is found on the magnetopause but is highly modulated by the interplanetary magnetic field (IMF) and time of day, turning "off" and "on" when the magnetic shear between the IMF and planetary fields is large enough. The simulation shows that the most likely location for reconnection to occur during Voyager 2's flyby was far from the spacecraft trajectory, which may explain the relative lack of associated signatures in the observations.

  5. Overview of the Cassini in-situ magnetosphere measurements and solar wind modelling during the 2013 Saturn Aurora Campaign

    Science.gov (United States)

    Bunce, E. J.; Badman, S. V.; Cowley, S. W. H.; Jinks, S. L.; Provan, G.; Burton, M.; Crary, F. J.; Dougherty, M. K.; Kurth, W. S.; Luhmann, J.; Mitchell, D. G.; Zheng, Y.

    2013-09-01

    The Saturn Aurora Campaign 2013 is a coordinated effort to provide a clearer understanding of Saturn's auroral emissions at multiple wavelengths in the upper atmosphere, and their associated magnetospheric signatures and dynamics. In addition, modelling and Earth-based observations of the solar wind conditions throughout the campaign provide an important insight to the way in which Saturn's magnetosphere responds to the changing conditions in interplanetary space. Structures such as Corotating Interaction Regions (CIRs) are thought to play a significant role in the modulation of Saturn's auroral emissions via abrupt changes in the dynamic pressure associated with forward shocks at the start of the CIR compression regions. Recent observations from the Cassini spacecraft at Saturn have also taught us that the "magnetosphere oscillations" observed in magnetic field perturbations in the northern and southern hemispheres, which are associated with the SKR modulations in each hemisphere, significantly affect the magnetosphere and auroral emissions. During April and May 2013 a combination of the Hubble Space Telescope (HST) ultraviolet (UV) instrument the Advanced Camera for Surveys (ACS), and ground-based infrared (IR) telescopes observed the northern hemisphere auroras, whilst the Cassini spacecraft's remote sensing instruments (the Ultraviolet Imaging Spectrograph-UVIS, the Visual and Infrared Mapping Spectrometer-VIMS, and the Imaging Science SubSystem-ISS) made simultaneous (or near-simultaneous) observations of the UV, IR and visible auroras respectively, in one or other hemisphere. At the same time, the "in situ" instruments on board Cassini measured the magnetic field, plasma populations, and radio plasma wave emissions in Saturn's magnetosphere. Here we present an overview of the in situ magnetosphere measurements during the campaign, along with an overview of the predicted solar wind conditions upstream of Saturn from modeling work. We will discuss the evidence

  6. The story of plumes: the development of a new conceptual framework for understanding magnetosphere and ionosphere coupling

    Science.gov (United States)

    Moldwin, Mark B.; Zou, Shasha; Heine, Tom

    2016-12-01

    The name "plume" has been given to a variety of plasma structures in the Earth's magnetosphere and ionosphere. Some plumes (such as the plasmasphere plume) represent elevated plasma density, while other plumes (such as the equatorial F region plume) represent low-density regions. Despite these differences these structures are either directly related or connected in the causal chain of plasma redistribution throughout the system. This short review defines how plumes appear in different measurements in different regions and describes how plumes can be used to understand magnetosphere-ionosphere coupling. The story of the plume family helps describe the emerging conceptual framework of the flow of high-density-low-latitude ionospheric plasma into the magnetosphere and clearly shows that strong two-way coupling between ionospheric and magnetospheric dynamics occurs not only in the high-latitude auroral zone and polar cap but also through the plasmasphere. The paper briefly reviews, highlights and synthesizes previous studies that have contributed to this new understanding.

  7. Ninth Workshop 'Solar Influences on the Magnetosphere, Ionosphere and Atmosphere'

    Science.gov (United States)

    Georgieva, Kayta; Kirov, Boian; Danov, Dimitar

    2017-08-01

    The 9th Workshop "Solar Influences on the Magnetosphere, Ionosphere and Atmosphere" is an international forum for scientists working in the fields of: Sun and solar activity, Solar wind-magnetosphere-ionosphere interactions, Solar influences on the lower atmosphere and climate, Solar effects in the biosphere, Instrumentation for space weather monitoring and Data processing and modelling.

  8. Composition measurements in the dusk flank magnetosphere

    Science.gov (United States)

    Fuselier, S. A.; Elphic, R. C.; Gosling, J. T.

    1999-03-01

    The dusk flank magnetosphere exhibits significant structure. Several regions have been identified, including the plasma sheet, mantle, and low latitude boundary layer. Transitions from one region to the next, for example from the mantle to the plasma sheet, can be abrupt or indistinct. In addition, the density within the flank mantle can range over several orders of magnitude. Although there is significant structure in this region of the magnetosphere, individual regions often can be distinguished by their energy spectra and ion composition. ISEE Fast Plasma Experiment and Plasma Composition Experiment data are used to examine the composition of the mantle and to study a set of transitions from the mantle to the plasma sheet where plasmas with mantle-like and plasma sheet-like energies mix. This study indicates that the variability of the mantle density is largely due to variability in the solar wind component (H+ and He2+); the ionospheric plasma (O+) density is roughly constant. Similarly, the plasma with mantle-like energy found in the mixed region is largely of solar wind origin.

  9. Quantitative magnetotail characteristics of different magnetospheric states

    Directory of Open Access Journals (Sweden)

    M. A. Shukhtina

    2004-03-01

    Full Text Available Quantitative relationships allowing one to compute the lobe magnetic field, flaring angle and tail radius, and to evaluate magnetic flux based on solar wind/IMF parameters and spacecraft position are obtained for the middle magnetotail, X=(–15,–35RE, using 3.5 years of simultaneous Geotail and Wind spacecraft observations. For the first time it was done separately for different states of magnetotail including the substorm onset (SO epoch, the steady magnetospheric convection (SMC and quiet periods (Q. In the explored distance range the magnetotail parameters appeared to be similar (within the error bar for Q and SMC states, whereas at SO their values are considerably larger. In particular, the tail radius is larger by 1–3 RE at substorm onset than during Q and SMC states, for which the radius value is close to previous magnetopause model values. The calculated lobe magnetic flux value at substorm onset is ~1GWb, exceeding that at Q (SMC states by ~50%. The model magnetic flux values at substorm onset and SMC show little dependence on the solar wind dynamic pressure and distance in the tail, so the magnetic flux value can serve as an important discriminator of the state of the middle magnetotail.

    Key words. Magnetospheric physics (solar windmagnetosphere- interactions, magnetotail, storms and substorms

  10. Pulsar Magnetospheres: Beyond the Flat Spacetime Dipole

    Science.gov (United States)

    Gralla, Samuel E.; Lupsasca, Alexandru; Philippov, Alexander

    2016-12-01

    Most studies of the pulsar magnetosphere have assumed a pure magnetic dipole in flat spacetime. However, recent work suggests that the effects of general relativity are in fact of vital importance and that realistic pulsar magnetic fields will have a significant nondipolar component. We introduce a general analytical method for studying the axisymmetric force-free magnetosphere of a slowly rotating star of arbitrary magnetic field, mass, radius, and moment of inertia, including all the effects of general relativity. We confirm that spacelike current is generically present in the polar caps (suggesting a pair production region), irrespective of the stellar magnetic field. We show that general relativity introduces a ∼ 60 % correction to the formula for the dipolar component of the surface magnetic field inferred from spindown. Finally, we show that the location and shape of the polar caps can be modified dramatically by even modestly strong higher moments. This can affect emission processes occurring near the star and may help explain the modified beam characteristics of millisecond pulsars.

  11. EMIC Waves in the Inner Magnetosphere

    Science.gov (United States)

    Usanova, M.; Mann, I. R.; Drozdov, A.; Orlova, K.; Shprits, Y.; Darrouzet, F.; Ergun, R.

    2015-12-01

    Electromagnetic ion cyclotron (EMIC) wave excitation in the inner magnetosphere has been the focus of extensive study over the past few decades, not only because of the role played by EMIC waves in ring current dynamics but also because of their potential importance for scattering radiation belt electrons into the atmosphere. Theory predicts that regions of enhanced cold dense plasma density embedded in relatively low background magnetic field (such as the outer equatorial plasmasphere or plasmaspheric plumes) should aid EMIC wave growth. Also, enhanced plasma density lowers the energy threshold for the resonant pitch angle scattering of outer radiation belt electrons such that EMIC waves can interact with electrons with energies below 1 MeV and hence could be a potentially important radiation belt loss mechanism. EMIC wave normal angle and polarization are also important properties that control the efficiency of their interaction with energetic particles. We will review recent statistical and single-event studies and focus on new understanding of EMIC wave characteristics and generation mechanisms in the inner equatorial magnetosphere - information extremely important for understanding energetic particle dynamics and in particular, for radiation belt and ring current modeling.

  12. GPS Navigation for the Magnetospheric Multi-Scale Mission

    Science.gov (United States)

    Bamford, William; Mitchell, Jason; Southward, Michael; Baldwin, Philip; Winternitz, Luke; Heckler, Gregory; Kurichh, Rishi; Sirotzky, Steve

    2009-01-01

    In 2014. NASA is scheduled to launch the Magnetospheric Multiscale Mission (MMS), a four-satellite formation designed to monitor fluctuations in the Earth's magnetosphere. This mission has two planned phases with different orbits (1? x 12Re and 1.2 x 25Re) to allow for varying science regions of interest. To minimize ground resources and to mitigate the probability of collisions between formation members, an on-board orbit determination system consisting of a Global Positioning System (GPS) receiver and crosslink transceiver was desired. Candidate sensors would be required to acquire GPS signals both below and above the constellation while spinning at three revolutions-per-minute (RPM) and exchanging state and science information among the constellation. The Intersatellite Ranging and Alarm System (IRAS), developed by Goddard Space Flight Center (GSFC) was selected to meet this challenge. IRAS leverages the eight years of development GSFC has invested in the Navigator GPS receiver and its spacecraft communication expertise, culminating in a sensor capable of absolute and relative navigation as well as intersatellite communication. The Navigator is a state-of-the-art receiver designed to acquire and track weak GPS signals down to -147dBm. This innovation allows the receiver to track both the main lobe and the much weaker side lobe signals. The Navigator's four antenna inputs and 24 tracking channels, together with customized hardware and software, allow it to seamlessly maintain visibility while rotating. Additionally, an extended Kalman filter provides autonomous, near real-time, absolute state and time estimates. The Navigator made its maiden voyage on the Space Shuttle during the Hubble Servicing Mission, and is scheduled to fly on MMS as well as the Global Precipitation Measurement Mission (GPM). Additionally, Navigator's acquisition engine will be featured in the receiver being developed for the Orion vehicle. The crosslink transceiver is a 1/4 Watt transmitter

  13. The Martian paleo-magnetosphere during the early Naochian and its implication for the early Martian atmosphere

    Science.gov (United States)

    Khodachenko, Maxim L.; Scherf, Manuel; Amerstorfer, Ute; Alexeev, Igor; Johnstone, Colin; Belenkaya, Elena; Tu, Lin; Lichtenegger, Herbert; Guedel, Manuel; Lammer, Helmut

    2016-10-01

    During the late 1990's the Mars Global Surveyor MAG/ER experiment detected crustal remanent magnetization at Mars indicating an ancient internal magnetic dynamo. The location of this remanent magnetization and in particular its absence at the large Martian impact craters like Hellas suggests a cessation of the dynamo during the early Naochian epoch, i.e. ~ 4.1 to 4 billion years ago. The strength of the remanent magnetization together with dynamo theory are indicating an ancient dipole field strength lying in the range of ~0.1 and ~1.0 of the present-day dipole field of the Earth, making the Martian paleo-magnetosphere comparable with the terrestrial paleo-magnetosphere. This also has implication for the early Martian atmosphere.In this poster we will present simulations of the paleo-magnetosphere of Mars for the early Naochian, just before cessation (i.e. for ~4.1 to ~4.0 billion years ago). These were performed with an adapted version of the Paraboloid Magnetospheric Model (PMM) of the Skobeltsyn Institute of Nuclear Physics of the Moscow State University, which serves as an ISO standard for the magnetosphere. Here the ancient magnetic field was assumed to be a dipole field (with dipole tilt ψ=0). The ancient solar wind ram pressure as important input parameter was derived from a newly developed solar/stellar wind evolution model, which is strongly dependent on the rotation rate of the early Sun. These simulations show that for the most extreme case of a fast rotating Sun and a paleomagnetic field strength of 0.1 of the present-day Earth value, the Martian magnetopause was located at ~5.5 RM (i.e. ~2.9 RE) above the Martian surface. Assuming a strong dipole field (i.e. 1.0 of present-day Earth) and a slow rotating Sun - our least extreme case - would lead to a standoff-distance of rs~16 RM (i.e. ~8.5 RE).Our simulations also have implications for the early Martian atmosphere, which will be demonstrated within this poster. These first results on the erosion of

  14. Detrimental Effects of Extreme Solar Activity on Life on Earth

    Science.gov (United States)

    Airapetian, Vladimir; Glocer, Alex; Jackman, Charles

    2015-07-01

    Solar Coronal Mass Ejections (CMEs), the most energetic eruptions in the Solar System, represent large-scale disturbances forming with the solar corona and are associated with solar flares and Solar Energetic Particles (SEP) events. Current Kepler data from solar-like stars suggest that the frequency of occurrence of energetic flares and associated CMEs from the Sun can be as high as 1 per 1500 years. What effects would CME and associated SEPs have on Earth's habitability? We have performed a three-dimensional time-dependent global magnetohydrodynamic simulation of the magnetic interaction of such a CME cloud with the Earth's magnetosphere. We calculated the global structure of the perturbed magnetosphere and derive the latitude of the open-closed magnetic field boundary. We used a 2D GSFC atmospheric code to calculate the efficiency of ozone depletion in the Earth's atmosphere due to SEP events and its effects on our society and life on Earth.

  15. High-energy galactic cosmic rays in the magnetospheres of terrestrial exoplanets

    Energy Technology Data Exchange (ETDEWEB)

    Griessmeier, Jean-Mathias [LPC2E/Universite d' Orleans/OSUC/CNRS, Orleans (France); Stadelmann, Anja [Technische Universitaet Braunschweig (Germany); Grenfell, Lee; Patzer, Beate [Technische Universitaet Berlin (Germany); Paris, Philip von [Univ. Bordeaux, LAB, UMR 5804, Floirac (France); CNRS, LAB, UMR 5804, Floirac (France); Lammer, Helmut [Space Research Institute, Austrian Academy of Sciences, Graz (Austria)

    2012-07-01

    Theoretical arguments indicate that close-in terrestial exoplanets may have weak magnetic fields, especially in the case of planets more massive than Earth (''super-Earths''). Planetary magnetic fields, however, constitute one of the shielding layers which protect the planet against cosmic ray particles. In particular, a weak magnetic field results in a high particle flux to the top of the planetary atmosphere. For the case of cosmic ray protons, we numerically analyze the propagation of the particles through planetary magnetospheres. We evaluate the efficiency of magnetospheric shielding as a function of the particle energy (in the range 64 MeV {<=} E {<=} 500 GeV) and of the planetary magnetic field strength (in the range 0.05 M{sub E} {<=} M {<=} 2 M{sub E}). We also show the dependence of the penetration energy on the planetary magnetic field strength. Implications of increased particle fluxes are discussed, including the modification of atmospheric chemistry, destruction of atmospheric biomarker molecules, and potential biological implications.

  16. Electron dynamics during substorm dipolarization in Mercury's magnetosphere

    Directory of Open Access Journals (Sweden)

    D. C. Delcourt

    2005-11-01

    Full Text Available We examine the nonlinear dynamics of electrons during the expansion phase of substorms at Mercury using test particle simulations. A simple model of magnetic field line dipolarization is designed by rescaling a magnetic field model of the Earth's magnetosphere. The results of the simulations demonstrate that electrons may be subjected to significant energization on the time scale (several seconds of the magnetic field reconfiguration. In a similar manner to ions in the near-Earth's magnetosphere, it is shown that low-energy (up to several tens of eV electrons may not conserve the second adiabatic invariant during dipolarization, which leads to clusters of bouncing particles in the innermost magnetotail. On the other hand, it is found that, because of the stretching of the magnetic field lines, high-energy electrons (several keVs and above do not behave adiabatically and possibly experience meandering (Speiser-type motion around the midplane. We show that dipolarization of the magnetic field lines may be responsible for significant, though transient, (a few seconds precipitation of energetic (several keVs electrons onto the planet's surface. Prominent injections of energetic trapped electrons toward the planet are also obtained as a result of dipolarization. These injections, however, do not exhibit short-lived temporal modulations, as observed by Mariner-10, which thus appear to follow from a different mechanism than a simple convection surge.

  17. Solar Imaging Radio Array (SIRA): Imaging solar, magnetospheric, and astrophysical sources at < 15 MHz

    Science.gov (United States)

    Howard, R.; MacDowall, R.; Gopalswamy, N.; Kaiser, M. L.; Reiner, M. J.; Bale, S.; Jones, D.; Kasper, J.; Weiler, K.

    2004-12-01

    The Solar Imaging Radio Array (SIRA) is a mission to perform aperture synthesis imaging of low frequency solar, magnetospheric, and astrophysical radio bursts. The primary science targets are coronal mass ejections (CMEs), which drive radio emission producing shock waves. A space-based interferometer is required, because the frequencies of observation (SIRA mission serves as a lower frequency counterpart to LWA, LOFAR, and similar ground-based radio imaging arrays. SIRA will require 12 to 16 microsatellites to establish a sufficient number of baselines with separations on the order of kilometers. The microsat constellation consists of microsats located quasi-randomly on a spherical shell, initially of radius 5 km or less. The baseline microsat is 3-axis stabilized with body-mounted solar arrays and an articulated, earth pointing high gain antenna. A retrograde orbit at 500,000 km from Earth was selected as the preferred orbit because it reduces the downlink requirement while keeping the microsats sufficiently distant from terrestrial radio interference. Also, the retrograde orbit permits imaging of terrestrial magnetospheric radio sources from varied perspectives. The SIRA mission serves as a pathfinder for space-based satellite constellations and for spacecraft interferometry at shorter wavelengths. It will be proposed to the NASA MIDEX proposal opportunity in mid-2005.

  18. End-to-End Study of the Transfer of Energy from Magnetosheath Ion Precipitation to the Ionospheric Cusp and Resulting Ion Outflow to the Magnetosphere

    Science.gov (United States)

    Coffey, Victoria; Chandler, Michael; Singh, Nagendra; Avanov, Levon

    2003-01-01

    We will show results from an end-to-end study of the energy transfer from injected magnetosheath plasmas to the near-Earth magnetospheric and ionospheric plasmas and the resulting ion outflow to the magnetosphere. This study includes modeling of the evolution of the magnetosheath precipitation in the cusp using a kinetic code with a realistic magnetic field configuration. These evolved, highly non-Maxwellian distributions are used as input to a 2D PIC code to analyze the resulting wave generation. The wave analysis is used in the kinetic code as input to the cold ionospheric ions to study the transfer of energy to these ions and their outflow to the magnetosphere. Observations from the Thermal Ion Dynamics Experiment (TIDE) and other instruments on the Polar Spacecraft will be compared to the modeling.

  19. IMF dependence of energetic oxygen and hydrogen ion distributions in the near-Earth plasma sheet

    Science.gov (United States)

    Luo, Hao; Kronberg, Elena; Nykyri, Katariina; Daly, Patrick; Chen, Gengxiong; Du, Aimin; Ge, Yasong

    2017-04-01

    Energetic ion distributions in the near-Earth plasma sheet can provide important information for understanding the entry of ions into the magnetosphere, and their transportation, acceleration, and losses in the near-Earth region. In this study, 11 years of energetic proton and oxygen observations (> 100 keV) from Cluster/RAPID were used to statistically study the energetic ion distributions in the near-Earth region. The dawn-dusk asymmetries of the distributions in three different regions (dayside magnetosphere, near-Earth nightside plasma sheet, and tail plasma sheet) are examined in northern and southern hemispheres. The results show that the energetic ion distributions are influenced by the dawn-dusk IMF direction. The enhancement of intensity largely correlates with the location of the magnetic reconnection at the magnetopause and the consequent formation of a diamagnetic cavity in the same quadrant of the magnetosphere. The results imply that substorm-related processes in the magnetotail are not the only source of energetic ions in the dayside and the near-Earth plasma sheet. We propose that large-scale cusp diamagnetic cavities can be an additional source and can thus significantly affect the energetic ion population in the magnetosphere. We also believe that the influence of the dawn-dusk IMF direction should not be neglected in models of the particle population in the magnetosphere.

  20. Motion of charged particles in pulsar magnetospheres

    Science.gov (United States)

    Zachariades, Haris Andrea

    The motion of charges in the magnetosphere of pulsars is studied from two complementary points of view: (1) for the case of aligned magnetic and rotational axes we solve a fluid version of the Lorentz-Dirac equation, in the Landau approximation, for a two-component plasma. We start from an approximately force-free initial condition and numerically integrate the equations of motion for a time equal to 1.6 percent of one stellar rotation period. We find that the system tends to a charge-separated state in which a negative charge region above the poles is separated by a vacuum gap from a positive charge region near the equator. We see the formation of force-free regions and a tendency of the vacuum gap to spread as the integrations proceed. The energies attained by the charges are only mildly relativistic and radiation reaction does not play an important role during the integrations. The negative charge above the polar region is electrostatically bound and there is a force-free region towards which negative charge tends to flow. Some positive charge is magnetically confined near the stellar equator and other positive charge crosses magnetic field lines moving outward to the region beyond the light cylinder. The outward motion of positive charge is due to the relative magnitudes of the electric and magnetic fields. (2) For the case of non-aligned axes we study the single particle dynamics for electrons moving in the region beyond the light cylinder, again using the Landau approximation to the Lorentz-Dirac equation. The effect of the inner magnetosphere is taken into account by adding a central attractive charge. We find that there exists a class of solutions corresponding to bounded orbits beyond the light cylinder. In an independent particle picture, particles started with different initial conditions within the basin of attraction of this class of orbits eventually form corotating patterns beyond the light cylinder. For a frequently occurring particle configuration

  1. Landau damping of magnetospherically reflected whistlers

    Science.gov (United States)

    Thorne, Richard M.; Horne, Richard B.

    1994-01-01

    Unducted VLF signals produced by lightning activity can form a population of magnetospherically reflected (MR) whistlers in the inner magnetosphere. It has been suggested recently that in the absence of significant attenuation such waves could merge into a broadband continuum with sufficient intensity to account for plasmaspheric hiss. To test this conjecture we have evaluated the path-integrated attenuation of MR whistlers along representative ray paths using the HOTRAY code. Using a realistic plasma distribution modeled on in-situ data, we find that the majority of MR waves experience significant damping after a few transits across the equator. This is primarily due to Landau resonance with suprathermal (0.1-1 keV) electrons. The attenuation is most pronounced for waves that propagate through the outer plasmasphere; this can readily account for the infrequent occurrence of multiple-hop MR waves for L greater than or equal to 3.5. Selected waves that originate at intermediate latitudes (15 deg is less than or equal to lambda is less than or equal to 35 deg) and whose ray paths are confined to the inner plasma- sphere may experience up to 10 magnetospheric reflections before substantial attentuation occurs. These waves should form the population of observed MR waves. Wave attenuation becomes more pronounced at higher frequencies; this can account for the absence of multiple-hop waves above 5 kHz. Weakly attenuated MR waves tend to migrate outward to the L shell, where their frequency is comparable to the equatorial lower hybrid frequency. The enhanced concentration of waves due to a merging of ray paths would produce a spectral feature that rises in frequency at lower L. This is quite distinct from the reported properties of plasmaspheric hiss, which maintains a constant frequency band throughout the entire plasmasphere. Furthermore, in the absence of mode conversion, waves below 500 Hz, which often form an important if not dominant part of the spectral properties

  2. Outer magnetospheric resonances and transport: discrete and turbulent cascades in the dynamic pressure and plasma flux

    Science.gov (United States)

    Savin, Sergey; Büchner, Jörg; Zelenyi, Lev; Kronberg, Elena; Kozak, Lyudmila; Blecki, Jan; Lezhen, Liudmila; Nemecek, Zdenek; Safrankova, Jana; Skalsky, Alexander; Budaev, Vyacheslav; Amata, Ermanno

    We explore interactions of Supersonic Plasma Streams (SPS) with the Earth magnetosphere in the context of the planetary and astrophysical magnetospheres and of that of laboratory plasmas. The interactions can be inherently non-local and non-equilibrium, and even explosive due to both solar wind (SW) induced and self-generated coherent structures in the multiscale system with the scales ranging from the micro to global scales. We concentrate on the main fundamental processes arising from the SPS cascading and interactions with surface and cavity resonances in the Earth’s magnetosphere, using multi-spacecraft data (SPECTR-R, DOUBLE STAR, CLUSTER, GEOTAIL, ACE, WIND etc.). We will address the following key problems to advance our understanding of anomalous transport and boundary dynamics: - generalizations of the SPS generation mechanisms, e.g., by bow shock (BS) surface or magnetosheath (MSH) cavity resonances, triggering by interplanetary shocks, solar wind (SW) dynamic pressure jumps, foreshock nonlinear structures, etc. - the clarification of BS rippling mechanisms requires base on the relevant databases from the CLUSTER/ DOUBLE STAR/ GEOTAIL/SPECTR-R/ ACE/ WIND spacecraft, which will be used for a statistical analysis targeting the SPS statistical features as extreme events. - substantial part of the SW kinetic energy can be pumped into the BS membrane and MSH cavity modes and initiate further cascades towards higher frequencies. Accordingly we present the multipoint studies of the SPS and of related nonlinear discrete cascades (carried generally by the SPS), along with the transformation of discrete cascades of the dynamic pressure into turbulent cascades. - investigation of spectral and bi-spectral cross-correlations in SW, foreshock, MSH and in vicinity of BS and magnetopause (MP) would demonstrate that both inflow and outflow into/ from magnetosphere can be modulated by the SPS and by the related outer magnetospheric resonances as well. We demonstrate in

  3. Modeling the ionosphere-thermosphere response to a geomagnetic storm using physics-based magnetospheric energy input: OpenGGCM-CTIM results

    Science.gov (United States)

    Connor, Hyunju Kim; Zesta, Eftyhia; Fedrizzi, Mariangel; Shi, Yong; Raeder, Joachim; Codrescu, Mihail V.; Fuller-Rowell, Tim J.

    2016-06-01

    The magnetosphere is a major source of energy for the Earth's ionosphere and thermosphere (IT) system. Current IT models drive the upper atmosphere using empirically calculated magnetospheric energy input. Thus, they do not sufficiently capture the storm-time dynamics, particularly at high latitudes. To improve the prediction capability of IT models, a physics-based magnetospheric input is necessary. Here, we use the Open Global General Circulation Model (OpenGGCM) coupled with the Coupled Thermosphere Ionosphere Model (CTIM). OpenGGCM calculates a three-dimensional global magnetosphere and a two-dimensional high-latitude ionosphere by solving resistive magnetohydrodynamic (MHD) equations with solar wind input. CTIM calculates a global thermosphere and a high-latitude ionosphere in three dimensions using realistic magnetospheric inputs from the OpenGGCM. We investigate whether the coupled model improves the storm-time IT responses by simulating a geomagnetic storm that is preceded by a strong solar wind pressure front on August 24, 2005. We compare the OpenGGCM-CTIM results with low-earth-orbit satellite observations and with the model results of Coupled Thermosphere-Ionosphere-Plasmasphere electrodynamics (CTIPe). CTIPe is an up-to-date version of CTIM that incorporates more IT dynamics such as a low-latitude ionosphere and a plasmasphere, but uses empirical magnetospheric input. OpenGGCM-CTIM reproduces localized neutral density peaks at ~ 400 km altitude in the high-latitude dayside regions in agreement with in situ observations during the pressure shock and the early phase of the storm. Although CTIPe is in some sense a much superior model than CTIM, it misses these localized enhancements. Unlike the CTIPe empirical input models, OpenGGCM-CTIM more faithfully produces localized increases of both auroral precipitation and ionospheric electric fields near the high-latitude dayside region after the pressure shock and after the storm onset, which in turn

  4. First multispacecraft ion measurements in and near the Earth’s magnetosphere with the identical Cluster ion spectrometry (CIS experiment

    Directory of Open Access Journals (Sweden)

    H. Rème

    Full Text Available On board the four Cluster spacecraft, the Cluster Ion Spectrometry (CIS experiment measures the full, three-dimensional ion distribution of the major magnetospheric ions (H+, He+, He++, and O+ from the thermal energies to about 40 keV/e. The experiment consists of two different instruments: a COmposition and DIstribution Function analyser (CIS1/CODIF, giving the mass per charge composition with medium (22.5° angular resolution, and a Hot Ion Analyser (CIS2/HIA, which does not offer mass resolution but has a better angular resolution (5.6° that is adequate for ion beam and solar wind measurements. Each analyser has two different sensitivities in order to increase the dynamic range. First tests of the instruments (commissioning activities were achieved from early September 2000 to mid January 2001, and the operation phase began on 1 February 2001. In this paper, first results of the CIS instruments are presented showing the high level performances and capabilities of the instruments. Good examples of data were obtained in the central plasma sheet, magnetopause crossings, magnetosheath, solar wind and cusp measurements. Observations in the auroral regions could also be obtained with the Cluster spacecraft at radial distances of 4–6 Earth radii. These results show the tremendous interest of multispacecraft measurements with identical instruments and open a new area in magnetospheric and solar wind-magnetosphere interaction physics.

    Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; magnetopheric configuration and dynamics; solar wind - magnetosphere interactions

  5. Observation of particle acceleration in laboratory magnetosphere

    CERN Document Server

    Kawazura, Yohei; Nishiura, Masaki; Saitoh, Haruhiko; Yano, Yoshihisa; Nogami, Tomoaki; Sato, Naoki; Yamasaki, Miyuri; Kashyap, Ankur; Mushiake, Toshiki

    2015-01-01

    The self-organization of magnetospheric plasma is brought about by inward diffusion of magnetized particles. Not only creating a density gradient toward the center of a dipole magnetic field, the inward diffusion also accelerates particles and provides a planetary radiation belt with high energy particles. Here, we report the first experimental observation of a 'laboratory radiation belt' created in the Ring Trap 1 (RT-1) device. By spectroscopic measurement, we found an appreciable anisotropy in the ion temperature, proving the betatron acceleration mechanism which heats particles in the perpendicular direction with respect to the magnetic field when particles move inward. The energy balance model including the heating mechanism explains the observed ion temperature profile.

  6. Observation of particle acceleration in laboratory magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Kawazura, Y.; Yoshida, Z.; Nishiura, M.; Saitoh, H.; Yano, Y.; Nogami, T.; Sato, N.; Yamasaki, M.; Kashyap, A.; Mushiake, T. [Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba 277-8561 (Japan)

    2015-11-15

    The self-organization of magnetospheric plasma is brought about by inward diffusion of magnetized particles. Not only creating a density gradient toward the center of a dipole magnetic field, the inward diffusion also accelerates particles and provides a planetary radiation belt with high energy particles. Here, we report the first experimental observation of a “laboratory radiation belt” created in the ring trap 1 device. By spectroscopic measurement, we found an appreciable anisotropy in the ion temperature, proving the betatron acceleration mechanism which heats particles in the perpendicular direction with respect to the magnetic field when particles move inward. The energy balance model, including the heating mechanism, explains the observed ion temperature profile.

  7. Centrifugal acceleration of plasma in pulsar magnetosphere

    Indian Academy of Sciences (India)

    R T Gangadhara; V Krishna

    2003-12-01

    We present a relativistic model for the centrifugal acceleration of plasma bunches and the coherent radio emission in pulsar magnetosphere. We find that rotation broadens the width of leading component compared to the width of trailing component. We explain this difference in the component widths using the nested cone emission geometry. We estimate the effect of pulsar spin on the Stokes parameters, and find that the inclination between the rotation and magnetic axes can introduce an asymmetry in the circular polarization of the conal components. We analyse the single pulse polarization data of PSR B0329+54 at 606 MHz, and find that in its conal components, one sense of circular polarization dominates in the leading component while the other sense dominates in the trailing component. Our simulation shows that changing the sign of the impact parameter changes the sense of circular polarization as well as the swing of polarization angle.

  8. Kinetic Theory of the Inner Magnetospheric Plasma

    CERN Document Server

    Khazanov, George V

    2011-01-01

    This book provides a broad introduction to the kinetic theory of space plasma physics with the major focus on the inner magnetospheric plasma. It is designed to provide a comprehensive description of the different kinds of transport equations for both plasma particles and waves with an emphasis on the applicability and limitations of each set of equations. The major topics are: Kinetic Theory of Superthermal Electrons, Kinetic Foundation of the Hydrodynamic Description of Space Plasmas (including wave-particle interaction processes), and Kinetic Theory of the Terrestrial Ring Current. Distinguishable features of this book are the analytical solutions of simplified transport equations. Approximate analytic solutions of transport phenomena are very useful because they help us gain physical insight into how the system responds to varying sources of mass, momentum and energy and also to various external boundary conditions. They also provide us a convenient method to test the validity of complicated numerical mod...

  9. Voyager 1: energetic ions and electrons in the jovian magnetosphere.

    Science.gov (United States)

    Vogt, R E; Cook, W R; Cummings, A C; Garrard, T L; Gehrels, N; Stone, E C; Trainor, J H; Schardt, A W; Conlon, T; Lal, N; McDonald, F B

    1979-06-01

    The observations of the cosmic-ray subsystem have added significantly to our knowledge of Jupiter's magnetosphere. The most surprising result is the existence of energetic sulfur, sodium, and oxygen nuclei with energies above 7 megaelectron volts per nucleon which were found inside of Io's orbit. Also, significant fluxes of similarly energetic ions reflecting solar cosmic-ray composition were observed throughout the magnetosphere beyond 11 times the radius of Jupiter. It was also found that energetic protons are enhanced by 30 to 70 percent in the active hemisphere. Finally, the first observations were made of the magnetospheric tail in the dawn direction out to 160 Jupiter radii.

  10. On the convective properties of magnetospheric Bernstein waves

    Science.gov (United States)

    Barbosa, D. D.

    1980-01-01

    Recent plasma wave observations made by the ISEE and GEOS satellites of the electrostatic cyclotron harmonic waves have been consistent with and organized very well within the theoretical framework of Bernstein waves excited in magnetospheric plasma. Attention is given to an examination of a number of effects that result simply from the convective properties of Bernstein waves in a magnetospheric plasma environment. The roles of wave trapping in plasma density depressions and partial trappings near the magnetic equator are discussed. Certain future wave observations are suggested that can improve the understanding of this magnetospheric wave phenomenon.

  11. On the convective properties of magnetospheric Bernstein waves

    Science.gov (United States)

    Barbosa, D. D.

    1980-01-01

    Recent plasma wave observations made by the ISEE and GEOS satellites of the electrostatic cyclotron harmonic waves have been consistent with and organized very well within the theoretical framework of Bernstein waves excited in magnetospheric plasma. Attention is given to an examination of a number of effects that result simply from the convective properties of Bernstein waves in a magnetospheric plasma environment. The roles of wave trapping in plasma density depressions and partial trappings near the magnetic equator are discussed. Certain future wave observations are suggested that can improve the understanding of this magnetospheric wave phenomenon.

  12. OSCILLATION-DRIVEN MAGNETOSPHERIC ACTIVITY IN PULSARS

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Meng-Xiang; Xu, Ren-Xin; Zhang, Bing, E-mail: linmx97@gmail.com, E-mail: r.x.xu@pku.edu.cn, E-mail: zhang@physics.unlv.edu [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China)

    2015-02-01

    We study the magnetospheric activity in the polar cap region of pulsars under stellar oscillations. The toroidal oscillation of the star propagates into the magnetosphere, which provides additional voltage due to unipolar induction, changes Goldreich-Julian charge density from the traditional value due to rotation, and hence influences particle acceleration. We present a general solution of the effect of oscillations within the framework of the inner vacuum gap model and consider three different inner gap modes controlled by curvature radiation, inverse Compton scattering, and two-photon annihilation, respectively. With different pulsar parameters and oscillation amplitudes, one of three modes would play a dominant role in defining the gap properties. When the amplitude of oscillation exceeds a critical value, mode changing occurs. Oscillations also lead to a change of the size of the polar cap. As applications, we show the inner gap properties under oscillations in both normal pulsars and anomalous X-ray pulsars/soft gamma-ray repeaters (AXPs/SGRs). We interpret the onset of radio emission after glitches/flares in AXPs/SGRs as due to oscillation-driven magnetic activities in these objects, within the framework of both the magnetar model and the solid quark star model. Within the magnetar model, radio activation may be caused by the enlargement of the effective polar cap angle and the radio emission beam due to oscillation, whereas within the solid quark star angle, it may be caused by activation of the pulsar inner gap from below the radio emission death line due to an oscillation-induced voltage enhancement. The model can also explain the glitch-induced radio profile change observed in PSR J1119–6127.

  13. Stamping the Earth from space

    CERN Document Server

    Dicati, Renato

    2017-01-01

    This unique book presents a historical and philatelic survey of Earth exploration from space. It covers all areas of research in which artificial satellites have contributed in designing a new image of our planet and its environment: the atmosphere and ionosphere, the magnetic field, radiation belts and the magnetosphere, weather, remote sensing, mapping of the surface, observation of the oceans and marine environments, geodesy, and the study of life and ecological systems. Stamping the Earth from Space presents the results obtained with the thousands of satellites launched by the two former superpowers, the Soviet Union and the United States, and also those of the many missions carried out by the ESA, individual European countries, Japan, China, India, and the many emerging space nations. Beautifully illustrated, it contains almost 1100 color reproductions of philatelic items. In addition to topical stamps and thematic postal documents, the book provides an extensive review of astrophilatelic items. The most...

  14. A comparison between ion characteristics observed by the POLAR and DMSP spacecraft in the high-latitude magnetosphere

    Directory of Open Access Journals (Sweden)

    T. J. Stubbs

    2004-03-01

    Full Text Available We study here the injection and transport of ions in the convection-dominated region of the Earth's magnetosphere. The total ion counts from the CAMMICE MICS instrument aboard the POLAR spacecraft are used to generate occurrence probability distributions of magnetospheric ion populations. MICS ion spectra are characterised by both the peak in the differential energy flux, and the average energy of ions striking the detector. The former permits a comparison with the Stubbs et al. (2001 survey of He2+ ions of solar wind origin within the magnetosphere. The latter can address the occurrences of various classifications of precipitating particle fluxes observed in the topside ionosphere by DMSP satellites (Newell and Meng, 1992. The peak energy occurrences are consistent with our earlier work, including the dawn-dusk asymmetry with enhanced occurrences on the dawn flank at low energies, switching to the dusk flank at higher energies. The differences in the ion energies observed in these two studies can be explained by drift orbit effects and acceleration processes at the magnetopause, and in the tail current sheet. Near noon at average ion energies of ≈1keV, the cusp and open LLBL occur further poleward here than in the Newell and Meng survey, probably due to convection- related time-of-flight effects. An important new result is that the pre-noon bias previously observed in the LLBL is most likely due to the component of this population on closed field lines, formed largely by low energy ions drifting earthward from the tail. There is no evidence here of mass and momentum transfer from the solar wind to the LLBL by non-reconnection coupling. At higher energies ≈2–20keV, we observe ions mapping to the auroral oval and can distinguish between the boundary and central plasma sheets. We show that ions at these energies relate to a transition from dawnward to duskward dominated flow, this is evidence of how ion drift orbits in the

  15. Impact of solar wind depression on the dayside magnetosphere under northward interplanetary magnetic field

    Directory of Open Access Journals (Sweden)

    S. Baraka

    2011-01-01

    Full Text Available We present a follow up study of the sensitivity of the Earth's magnetosphere to solar wind activity using a particles-in-cell model (Baraka and Ben Jaffel, 2007, but here during northward Interplanetary Magnetic Field (IMF. The formation of the magnetospheric cavity and its elongation around the planet is obtained with the classical structure of a magnetosphere with parallel lobes. An impulsive disturbance is then applied to the system by changing the bulk velocity of the solar wind to simulate a decrease in the solar wind dynamic pressure followed by its recovery. In response to the imposed drop in the solar wind velocity, a gap (abrupt depression in the incoming solar wind plasma appears moving toward the Earth. The gap's size is a ~15 RE and is comparable to the sizes previously obtained for both Bz<0 and Bz=0. During the initial phase of the disturbance along the x-axis, the dayside magnetopause (MP expands slower than the previous cases of IMF orientations as a result of the abrupt depression. The size of the MP expands nonlinearly due to strengthening of its outer boundary by the northward IMF. Also, during the initial 100 Δt, the MP shrank down from 13.3 RE to ~9.2 RE before it started expanding, a phenomenon that was also observed for southern IMF conditions but not during the no IMF case. As soon as they felt the solar wind depression, cusps widened at high altitude while dragged in an upright position. For the field's topology, the reconnection between magnetospheric and magnetosheath fields is clearly observed in both the northward and southward cusps areas. Also, the tail region in the northward IMF condition is more confined, in contrast to the fishtail-shape obtained in the southward IMF case. An X-point is formed in the tail at ~110 RE compared to ~103 RE and ~80 RE for

  16. Rapid enhancement of energetic oxygen ions in the inner magnetosphere during substorms

    Science.gov (United States)

    Nakayama, Y.; Ebihara, Y.; Tanaka, T.

    2014-12-01

    Satellite observations show that energetic (>100 keV) O+ ions are rapidly increased in the inner magnetosphere during substorms. The ultimate source of O+ ions is the Earth's ionosphere, so that O+ ions must be accelerated from ~eV to 100s keV somewhere in the magnetosphere. A fundamental question still arise regarding why O+ ions are accelerated and transported to the inner magnetosphere. We simulated substorms under two different solar wind conditions by using the global MHD simulation developed by Tanaka et al. (2010, JGR). The solar wind speed is set to be 372 km/s for Case I, and 500 km/s for Case II. In both cases, the MHD simulation result shows that the dawn to dusk electric field is enhanced in the night side tail region at >7 Re just after the substorm onset. In particular, the electric field in the inner region (~7 Re) is highly enhanced by the tension force because of relatively strong magnetic field together with curved field lines. The strongest electric field takes place near the region where the plasma pressure is high. We performed test particle simulation under the electric and magnetic fields for Cases I and II. O+ ions are released from two planes located at ±2 Re in the Z direction in the tail region. O+ ions released at the two planes represent outflowing stream of O+ ions escaping from the Earth. The distribution function at the planes is assumed to be drifting Kappa distribution with temperature of 10 eV, the density of 105 m-3, and the parallel velocity given by the MHD simulation. In total, around a billion of particles are traced. Each test particle carries the real number of particles in accordance with the Liouville theorem. After tracing particles, we reconstructed 6-dimensional phase space density of O+ ions. We obtained the following results. (1) Just after substorm onset, the differential flux of O+ ions is almost simultaneously enhanced in the region where the electric field is strong. (2) The kinetic energy increases rapidly to

  17. Magnetospheric effects in atmospheric electricity at high latitudes

    Science.gov (United States)

    Shumilov, O. I.; Kasatkina, E. A.; Frank-Kamenetsky, A. V.; Raspopov, O. M.; Vasiljev, A. N.; Struev, A. G.

    2003-04-01

    Measurements of the vertical atmospheric electric field (Ez) made at auroral station Apatity (geomagnetic latitude: 63.8) and polar cap station Vostok, Antarctica (geomagnetic latitude: -89.3) in 2001-2002 have been analyzed. The measurements were made by a high-latitude computer-aided complex installed at Apatity in 2001. It consists of three spatially placed microbarographs for measurements of atmospheric waves, a device for air conductivity measurement and a device for measurement of vertical component of the atmospheric electric field. The computer-aided system permits to get information with a frequency of five times per second. The ground level atmospheric electric field was found to have systematic local diurnal and seasonal variations. Diurnal variations of atmospheric potential gradient were found to have a departure from the Carnegie curve. A distinct difference in the diurnal variation of atmospheric electric field has been observed also between disturbed (Kp>30) and extremely quiet (Kplatitude electric field variations appear to be the result of solar wind-magnetosphere-ionosphere coupling. Besides, we have found the similarity between the diurnal course of the atmospheric electric field under the quiet geomagnetic conditions and the diurnal variation of galactic cosmic rays. These results have been explained in terms of calculated effective Bz component of the interpalnetary magnetic field arising due to variation of the geomagnetic dipole axis inclination during the Earth's rotation. The results of analysis of the influence of extreme weather conditions (rain, snow, snowstorm, stormclouds, thunderstorms, lightning) on atmospheric electricity (electric field and conductivity) are also discussed. This work was supported by EC (grant INTAS 97-31008) and RFBR (grant 01-05-64850).

  18. Energetic particle sounding of the magnetospheric cusp with ISEE-1

    Directory of Open Access Journals (Sweden)

    K. E. Whitaker

    2007-06-01

    Full Text Available Observations on 30 October 1978 show the ISEE-1 spacecraft passing though the high-altitude dayside northern magnetospheric cusp region from roughly 16:00 to 18:30 UT, during a slow solar wind period (~380 km/s. More than two orders of magnitude enhancements of the cusp energetic particle (CEP fluxes were observed along with a depressed and turbulent local magnetic field. The observed variations of the pitch angle distributions (PAD provide a unique opportunity to determine the structure of the cusp and the origin of the CEP. Through a boundary sounding technique, the location and orientation of the cusp poleward (or backside boundary was observed for almost 10 min during which time it appeared initially to be stationary in the GSM/GSE X-direction and then moved sunward about 0.12 Earth radii (RE. The orientation remained approximately perpendicular to the GSM/GSE X-axis until it was observed to rotate by 60 degrees in ~3 min before ISEE-1 was fully inside the cusp cavity. The cavity itself was filled with CEP fluxes displaying large anisotropies, indicative of their source being located below (Earthward of the satellite location. The spacecraft entered from the backside of the cusp, then traveled ~4 RE through the cavity, and exited through the "top" of the cavity leaving a region of energetic ions below. The PADs demonstrate that the bow shock cannot be the main source of the observed CEPs. The CEP fluxes were measured at about 8.5 h MLT when the IMF had both an 8–10 nT duskward and southward component.

  19. Modeling whistler wave generation regimes in magnetospheric cyclotron maser

    Directory of Open Access Journals (Sweden)

    D. L. Pasmanik

    2004-11-01

    Full Text Available Numerical analysis of the model for cyclotron instability in the Earth's magnetosphere is performed. This model, based on the self-consistent set of equations of quasi-linear plasma theory, describes different regimes of wave generation and related energetic particle precipitation. As the source of free energy the injection of energetic electrons with transverse anisotropic distribution function to the interaction region is considered. A parametric study of the model is performed. The main attention is paid to the analysis of generation regimes for different characteristics of energetic electron source, such as the shape of pitch angle distributions and its intensity. Two mechanisms of removal of energetic electrons from a generation region are considered, one is due to the particle precipitation through the loss cone and another one is related to the magnetic drift of energetic particles.

    It was confirmed that two main regimes occur in this system in the presence of a constant particle source, in the case of precipitation losses. At small source intensity relaxation oscillations were found, whose parameters are in good agreement with simplified analytical theory developed earlier. At a larger source intensity, transition to a periodic generation occurs. In the case of drift losses the regime of self-sustained periodic generation regime is realized for source intensity higher than some threshold. The dependencies of repetition period and dynamic spectrum shape on the source parameters were studied in detail. In addition to simple periodic regimes, those with more complex spectral forms were found. In particular, alteration of spikes with different spectral shape can take place. It was also shown that quasi-stationary generation at the low-frequency band can coexist with periodic modulation at higher frequencies.

    On the basis of the results obtained, the model for explanation of

  20. Energetic particle drift motions in the outer dayside magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Buck, R.M.

    1987-12-01

    Models of the geomagnetic field predict that within a distance of approximately one earth radius inside the dayside magnetopause, magnetic fields produced by the Chapman-Ferraro magnetopause currents create high-latitude minimum-B ''pockets'' in the geomagnetic field. Drift-shell branching caused by the minimum-B pockets is analyzed and interpreted in terms of an adiabatic shell branching and rejoining process. We examine the shell-branching process for a static field in detail, using the Choe-Beard 1974 magnetospheric magnetic field model. We find that shell branching annd rejoining conserves the particle mirror field B/sub M/, the fieldline integral invariant I, and the directional electron flux j. We determine the spatial extent of the stable trapping regions for the Choe-Beard model. We develop an adiabatic branching map methodology which completely identifies and describes the location of shell-branching points and the adiabatic trajectories of particles on branched shells, for any model field. We employ the map to develop synthetic pitch angle distributions near the dayside magnetopause by adiabatically transforming observed midnight distributions to the dayside. We find that outer dayside lines contain particles moving on branched and unbranched shells, giving rise to distinctive pitch angle distribution features. We find a good correlation between the pitch angles which mark the transition from branched to unbranched shells in the model, and the distinctive features of the OGO-5 distributions. In the morning sector, we observe large flux changes at critical pitch angles which correspond to B-pocket edges in the model. Measurements on inbound passes in the afternoon sector show first the adiabatic particle shadow, then the arrival of fluxes on rejoined shells, then fluxes on unbranced shells - in accord with model predictions. 204 refs., 138 figs., 2 tabs.

  1. A New Approach to Isolating External Magnetic Field Components in Spacecraft Measurements of the Earth's Magnetic Field Using Global Positioning System observables

    Science.gov (United States)

    Raymond, C.; Hajj, G.

    1994-01-01

    We review the problem of separating components of the magnetic field arising from sources in the Earth's core and lithosphere, from those contributions arising external to the Earth, namely ionospheric and magnetospheric fields, in spacecraft measurements of the Earth's magnetic field.

  2. From the Solar Wind to the Magnetospheric Substorm

    Institute of Scientific and Technical Information of China (English)

    E.A. Ponomarev; P.A. Sedykh; O.V. Mager

    2005-01-01

    This paper gives a brief outline of the progression from the first substorm model developed in Ref.[4] and [8] based on Kennel's ideas[3], to the present views about the mechanism by which solar wind kinetic energy is converted to electromagnetic energy at the Bow Shock and by which this energy is transferred to the magnetosphere in the form of current; about the transformation of the energy of this current to gas kinetic energy of convecting plasma tubes, and, finally, the back transformation of gas kinetic energy to electromagnetic energy in secondary magnetospheric MHD generators. The questions of the formation of the magnetospheric convection system, the nature of substorm break-up, and of the matching of currents in the magnetosphere-ionosphere system are discussed.

  3. Magnetosphere-Ionosphere Coupling and Field-Aligned Currents

    CERN Document Server

    Oliveira, D M

    2015-01-01

    It is presented in this paper a review of one of several interactions between the magnetosphere and the ionosphere through the field-aligned currents (FACs). Some characteristics and physical implications of the currents flowing in a plane perpendicular to the magnetic field at high latitudes are discussed. The behavior of this system as an electric circuit is explained, where momentum and energy are transferred via Poynting flux from the magnetosphere into the ionosphere.

  4. Role of magnetospheric plasma physics for understanding cosmic phenomena

    Science.gov (United States)

    Das, Indra M. L.

    Cosmic phenomena occur in the remote regions of space where in situ observations are not possible. For a proper understanding of these phenomena, laboratory experiments are essential, but in situ observations of magnetospheric plasma provide an even better background to test various hypothesis of cosmic interest. This is because the ionospheric-magnetospheric plasma and the solar wind are the only cosmic plasmas accessible to extensive in situ observations and experiments.

  5. Quantitative Simulation of a Magnetospheric Substorm. 2. Comparison with Observations,

    Science.gov (United States)

    1980-01-23

    we overestimated the polar-boundary potential drop; consequently the p) asma -sheet ions were injected deeper into the magnetosphere than was the case...Magnetospheric Substorms and Related Plasma Processes, Los Alamos, New Mexico , October 1978 and to be published in Astrophysics and Space Science Library...and Related Plasma Processes, Los Alamos, New Mexico , October 1978, published in Astrophysics and Space Science Library Series,p.14 3, Yasuhara, F., and

  6. Modeling and analysis of solar wind generated contributions to the near-Earth magnetic field

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Moretto, T.; Rastatter, L.

    2006-01-01

    Solar wind generated magnetic disturbances are currently one of the major obstacles for improving the accuracy in the determination of the magnetic field due to sources internal to the Earth. In the present study a global MHD model of solar wind magnetosphere interaction is used to obtain...... a physically consistent, divergence-free model of ionospheric, field-aligned and magnetospheric currents in a realistic magnetospheric geometry. The magnetic field near the Earth due to these currents is analyzed by estimating and comparing the contributions from the various parts of the system, with the aim....... At high latitudes the field-aligned component is of partidular interest in connection with internal field-modelling. In the attitude regime of 400-800 km (typical for low Earth orbit satellites) the ionospheric currents are found to contribute significantly to the disturbancance, and account for more than...

  7. Expanding earth

    Energy Technology Data Exchange (ETDEWEB)

    Carey, S.W.

    1976-01-01

    Arguments in favor of an expanding earth are presented. The author believes that the theory of plate tectonics is a classic error in the history of geology. The case for the expanding earth is organized in the following way: introductory review - face of the earth, development of expanding earth concept, necessity for expansion, the subduction myth, and definitions; some principles - scale of tectonic phenomena, non-uniformitarianism, tectonic profile, paleomagnetism, asymmetry of the earth, rotation of the earth, and modes of crustal extension; regional studies - western North America, Central America, South-East Asia, and the rift oceans; tests and cause of expansion. 824 references, 197 figures, 11 tables. (RWR)

  8. A Solar Cycle Dependence of Nonlinearity in Magnetospheric Activity

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Jay R; Wing, Simon

    2005-03-08

    The nonlinear dependencies inherent to the historical K(sub)p data stream (1932-2003) are examined using mutual information and cumulant based cost as discriminating statistics. The discriminating statistics are compared with surrogate data streams that are constructed using the corrected amplitude adjustment Fourier transform (CAAFT) method and capture the linear properties of the original K(sub)p data. Differences are regularly seen in the discriminating statistics a few years prior to solar minima, while no differences are apparent at the time of solar maximum. These results suggest that the dynamics of the magnetosphere tend to be more linear at solar maximum than at solar minimum. The strong nonlinear dependencies tend to peak on a timescale around 40-50 hours and are statistically significant up to one week. Because the solar wind driver variables, VB(sub)s and dynamical pressure exhibit a much shorter decorrelation time for nonlinearities, the results seem to indicate that the nonlinearity is related to internal magnetospheric dynamics. Moreover, the timescales for the nonlinearity seem to be on the same order as that for storm/ring current relaxation. We suggest that the strong solar wind driving that occurs around solar maximum dominates the magnetospheric dynamics suppressing the internal magnetospheric nonlinearity. On the other hand, in the descending phase of the solar cycle just prior to solar minimum, when magnetospheric activity is weaker, the dynamics exhibit a significant nonlinear internal magnetospheric response that may be related to increased solar wind speed.

  9. Pulsar magnetosphere: a new view from PIC simulations

    Science.gov (United States)

    Brambilla, Gabriele; Kalapotharakos, Constantions; Timokhin, Andrey; Harding, Alice; Kazanas, Demosthenes

    2017-01-01

    Pulsar emission is produced by charged particles that are accelerated as they flow in the star's magnetosphere. The magnetosphere is populated by electrons and positrons while the physical conditions are characterized by the so called force-free regime. However, the magnetospheric plasma configuration is still unknown, besides some general features, which inhibits the understanding of the emission generation. Here we show the closest to force-free solution ever obtained with a particle-in-cell (PIC) code. The importance of obtaining a force-free solution with PIC is that we can understand how the different particle species support the corresponding magnetosphere structure. Moreover, some aspects of the emission generation are captured. These are the necessary steps to go toward a self consistent modeling of the magnetosphere, connecting the microphysics of the pair plasma to its macroscopic quantities. Understanding the pulsar magnetosphere is essential for interpreting the broad neutron star phenomenology (young pulsars, magnetars, millisecond pulsars, etc.). The study of these plasma physics processes is also crucial for putting limits on the ability of these objects to accelerate particles.

  10. Enhancements of magnetospheric convection electric field associated with sudden commencements in the inner magnetosphere and plasmasphere regions

    Science.gov (United States)

    Shinbori, A.; Ono, T.; Iizima, M.; Kumamoto, A.; Nishimura, Y.

    2006-01-01

    Electric field variations in the inner magnetosphere and plasmasphere regions associated with sudden commencements (SCs) are investigated by using the observation data of the Akebono satellite which has been carried out more than 15 years since 1989. 117 of 153 SC events in the low-latitude (MLAT bi-polar waveform due to the passage of fast-mode hydromagnetic (HM) waves. The increase of the convection electric field takes place in the entire magnetic local time sector in the inner magnetosphere. The amplitude does not depend on L-value and magnetic local time but is proportional to the SC amplitude measured at Kakioka. The majority of the electric field enhancements persist for about 4 14 min. The origin of the convection electric field in the inner magnetosphere is a plasma motion caused by the compression of the magnetosphere due to the solar wind shock and discontinuity.

  11. Symmetric or asymmetric energy transfer from ICMEs to the magnetosphere depending on the solar dipole

    Science.gov (United States)

    Baranyi, T.; Ludmány, A.

    The annual behaviour of monthly number of hours spent by the Earth in domains of either positive or negative By component of interplanetary magnetic field (IMF) was studied. We used the hourly OMNI data in the cases of Kp>3. The study was confined to the ascending phases of the four recent sunspot cycles when CMEs dominate among the sources of geoeffectiveness. Definite differences were found between the annual variations of the hourly sums. When the solar dipole is opposite to the terrestrial one, the sums exhibit the the combined effect of Rosenberg-Coleman and Russell-McPherron effects. Thus, in the geomagnetically active hours the negative By dominates in spring and the positive By dominates in fall. However, these effects can not be detected in the occurrence of the negative and positive GSM By values when the solar and terrestrial dipoles are parallel. In this case one can see polarity-independent semiannual variations instead of the polarity-dependent opposite annual variations. It is well-known that the By component modulates the energy transfer from the solar wind to the magnetosphere causing marked asymmetries in magnetospheric convective flow pattens at high latitudes. Our results hint that the occurrences of these asymmetries related to the ICMEs depend on the solar dipole cycle. In the antiparallel years one of them dominates during half a year causing asymmetric energy transfer to the magnetosphere. In the parallel years the occurrences of the two kind of asymmetries are equal on monthly time scale, thus the energy transfer is symmetric within a monthly and yearly time interval.

  12. Prompt acceleration of magnetospheric electrons to ultrarelativistic energies by the 17 March 2015 interplanetary shock

    Science.gov (United States)

    Kanekal, S. G.; Baker, D. N.; Fennell, J. F.; Jones, A.; Schiller, Q.; Richardson, I. G.; Li, X.; Turner, D. L.; Califf, S.; Claudepierre, S. G.; Wilson, L. B., III; Jaynes, A.; Blake, J. B.; Reeves, G. D.; Spence, H. E.; Kletzing, C. A.; Wygant, J. R.

    2016-08-01

    Trapped electrons in Earth's outer Van Allen radiation belt are influenced profoundly by solar phenomena such as high-speed solar wind streams, coronal mass ejections (CME), and interplanetary (IP) shocks. In particular, strong IP shocks compress the magnetosphere suddenly and result in rapid energization of electrons within minutes. It is believed that the electric fields induced by the rapid change in the geomagnetic field are responsible for the energization. During the latter part of March 2015, a CME impact led to the most powerful geomagnetic storm (minimum Dst = -223 nT at 17 March, 23 UT) observed not only during the Van Allen Probe era but also the entire preceding decade. Magnetospheric response in the outer radiation belt eventually resulted in elevated levels of energized electrons. The CME itself was preceded by a strong IP shock whose immediate effects vis-a-vis electron energization were observed by sensors on board the Van Allen Probes. The comprehensive and high-quality data from the Van Allen Probes enable the determination of the location of the electron injection, timescales, and spectral aspects of the energized electrons. The observations clearly show that ultrarelativistic electrons with energies E > 6 MeV were injected deep into the magnetosphere at L ≈ 3 within about 2 min of the shock impact. However, electrons in the energy range of ≈250 keV to ≈900 keV showed no immediate response to the IP shock. Electric and magnetic fields resulting from the shock-driven compression complete the comprehensive set of observations that provide a full description of the near-instantaneous electron energization.

  13. Different facets of dynamical complexity in the magnetosphere - A recurrence perspective

    Science.gov (United States)

    Stolbova, Veronika; Donner, Reik V.; Donges, Jonathan F.; Georgiou, Marina; Balasis, Georgios; Potirakis, Stelios; Kurths, Jürgen

    2014-05-01

    Modern human civilizations rely to a great extent on the proper functioning of infrastructures such as communication and electrical power generation and supply. Natural hazards present an ongoing threat to these infrastructures. Whereas earthquakes, storms and other types of disasters associated with the Earth's internal dynamics have mostly local to regional effects, severe magnetic storms (most prominently those following strong solar eruptions) and related phenomena have the particular potential of affecting large parts of the globe at once (in case of damaging communication infrastructures relying on satellite transmissions, they even have global hazardous potential). In order to better understanding the variations between quiescence and activity phases of the Earth's magnetic field, the complex structure of fluctuations of magnetic field strength needs to be carefully analyzed. In this work, we utilize the powerful framework of recurrence analysis for studying the properties of the Earth's magnetosphere during one year of observations including several quiescence and activity phases. Specifically, we apply several measures of recurrence quantification analysis (RQA) and recurrence network analysis (RNA) to hourly values of the disturbance storm-time (Dst) index for the year 2001. Both RQA and RNA have recently shown their great potentials for tracing variations in dynamical complexity in non-stationary models as well as real-world time series, including various applications to geoscientific problems. Here, both frameworks are used for the first time to study the complex signatures of magnetospheric fluctuations during non-storm and storm conditions. Our results reveal that recurrence characteristics provide excellent tracers for changes in the dynamical complexity along non-stationary records of geomagnetic activity. In particular, trapping time (characterizing the typical length of "laminar phases" in the observed dynamics) and network transitivity

  14. Data Services Required for Future Magnetospheric Research

    Science.gov (United States)

    McPherron, R. L.

    2006-05-01

    Magnetospheric research today has gone far beyond the search for new phenomena in the data from a single instrument on a single spacecraft. Typical studies today are either case histories of several events using data from many instruments in many locations or statistical studies of very long records. Most existing data services are not designed to support such studies. Individual and group data bases, mission data archives, data centers, and future virtual observatories will all be sources of data for future research. To facilitate this research these data sources must satisfy a number of requirements. These include: the data must be publicly accessible via the internet; the data must exist in well organized file systems; the data must have accompanying metadata; the data should exist or be delivered in processed form; the delivered data should be in an easily used format; it should not be necessary to repeatedly fill forms to obtain long data sets; there should be no arbitrary limits on the amount of data provided in a single request. In addition to data there exist certain forms of data processing that are better done in specialized facilities. Some examples of this include: generation of survey plot; coordinate transformation; calculation of spacecraft orbits; propagation of solar wind data; projection of images; evaluation of complex models. In this paper we will discuss the justification for these and other requirements in facilitating research through a distributed Great Observatory.

  15. Energetic Particles Dynamics in Mercury's Magnetosphere

    Science.gov (United States)

    Walsh, Brian M.; Ryou, A.S.; Sibeck, D. G.; Alexeev, I. I.

    2013-01-01

    We investigate the drift paths of energetic particles in Mercury's magnetosphere by tracing their motion through a model magnetic field. Test particle simulations solving the full Lorentz force show a quasi-trapped energetic particle population that gradient and curvature drift around the planet via "Shabansky" orbits, passing though high latitudes in the compressed dayside by equatorial latitudes on the nightside. Due to their large gyroradii, energetic H+ and Na+ ions will typically collide with the planet or the magnetopause and will not be able to complete a full drift orbit. These simulations provide direct comparison for recent spacecraft measurements from MESSENGER. Mercury's offset dipole results in an asymmetric loss cone and therefore an asymmetry in particle precipitation with more particles precipitating in the southern hemisphere. Since the planet lacks an atmosphere, precipitating particles will collide directly with the surface of the planet. The incident charged particles can kick up neutrals from the surface and have implications for the formation of the exosphere and weathering of the surface

  16. Inductive ionospheric solver for magnetospheric MHD simulations

    Directory of Open Access Journals (Sweden)

    H. Vanhamäki

    2011-01-01

    Full Text Available We present a new scheme for solving the ionospheric boundary conditions required in magnetospheric MHD simulations. In contrast to the electrostatic ionospheric solvers currently in use, the new solver takes ionospheric induction into account by solving Faraday's law simultaneously with Ohm's law and current continuity. From the viewpoint of an MHD simulation, the new inductive solver is similar to the electrostatic solvers, as the same input data is used (field-aligned current [FAC] and ionospheric conductances and similar output is produced (ionospheric electric field. The inductive solver is tested using realistic, databased models of an omega-band and westward traveling surge. Although the tests were performed with local models and MHD simulations require a global ionospheric solution, we may nevertheless conclude that the new solution scheme is feasible also in practice. In the test cases the difference between static and electrodynamic solutions is up to ~10 V km−1 in certain locations, or up to 20-40% of the total electric field. This is in agreement with previous estimates. It should also be noted that if FAC is replaced by the ground magnetic field (or ionospheric equivalent current in the input data set, exactly the same formalism can be used to construct an inductive version of the KRM method originally developed by Kamide et al. (1981.

  17. Inductive ionospheric solver for magnetospheric MHD simulations

    Science.gov (United States)

    Vanhamäki, H.

    2011-01-01

    We present a new scheme for solving the ionospheric boundary conditions required in magnetospheric MHD simulations. In contrast to the electrostatic ionospheric solvers currently in use, the new solver takes ionospheric induction into account by solving Faraday's law simultaneously with Ohm's law and current continuity. From the viewpoint of an MHD simulation, the new inductive solver is similar to the electrostatic solvers, as the same input data is used (field-aligned current [FAC] and ionospheric conductances) and similar output is produced (ionospheric electric field). The inductive solver is tested using realistic, databased models of an omega-band and westward traveling surge. Although the tests were performed with local models and MHD simulations require a global ionospheric solution, we may nevertheless conclude that the new solution scheme is feasible also in practice. In the test cases the difference between static and electrodynamic solutions is up to ~10 V km-1 in certain locations, or up to 20-40% of the total electric field. This is in agreement with previous estimates. It should also be noted that if FAC is replaced by the ground magnetic field (or ionospheric equivalent current) in the input data set, exactly the same formalism can be used to construct an inductive version of the KRM method originally developed by Kamide et al. (1981).

  18. Simultaneous observations of solar MeV particles in a magnetic cloud and in the earth's northern tail lobe - Implications for the global field line topology of magnetic clouds and for the entry of solar particles into the magnetosphere during cloud passage

    Science.gov (United States)

    Farrugia, C. J.; Richardson, I. G.; Burlaga, L. F.; Lepping, R. P.; Osherovich, V. A.

    1993-01-01

    Simultaneous ISEE 3 and IMP 8 spacecraft observations of magnetic fields and flow anisotropies of solar energetic protons and electrons during the passage of an interplanetary magnetic cloud show various particle signature differences at the two spacecraft. These differences are interpretable in terms of the magnetic line topology of the cloud, the connectivity of the cloud field lines to the solar surface, and the interconnection between the magnetic fields of the magnetic clouds and of the earth. These observations are consistent with a magnetic cloud model in which these mesoscale configurations are curved magnetic flux ropes attached at both ends to the sun's surface, extending out to 1 AU.

  19. ACE EPAM and Van Allen Probes RBSPICE measurements of interplanetary oxygen injection to the inner magnetosphere

    Science.gov (United States)

    Patterson, J. D.; Manweiler, J. W.; Gerrard, A. J.; Lanzerotti, L. J.

    2015-12-01

    On March 17, 2015, a significant oxygen-rich interplanetary event was measure by the Advanced Composition Explorer (ACE) Electron Proton Alpha Monitor (EPAM) instrument. At the same time the Van Allen Probes Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instrument recorded significant enhancements of oxygen in the inner magnetosphere. We present a detailed analysis of this event utilizing a new method of exploiting the EPAM Pulse Height Analyzer (PHA) data to precisely resolve helium and oxygen spectra within the 0.5 to 5 MeV/nuc range. We also present the flux, partial particle pressures, and pitch angle distributions of the ion measurements from RBSPICE. During this event, both EPAM and RBSPICE measured O:He ratios greater than 10:1. The pitch angle distributions from RBSPICE-B show a strong beam of oxygen at an L ~ 5.8 early on March 17th during orbit. The timing between the observations of the oxygen peak at ACE and the beam observed at RBSPICE-B is consistent with the travel-time required for energetic particle transport from L1 to Earth and access to the magnetosphere. We assert that the oxygen seen by RBSPICE during the initial phase of this event is the result of direct injection from the interplanetary medium of energetic ions. This poster contains the observations and detailed calculations to support this assertion.

  20. Some evidence of ground power enhancements at frequencies of global magnetospheric modes at low latitude

    Directory of Open Access Journals (Sweden)

    P. Francia

    Full Text Available A statistical analysis of the power spectra of the geomagnetic field components H and D for periods ranging between 3 min and 1 h was conducted at a low-latitude observatory (L'Aquila, L=1.6 at the minimum and maximum of the solar cycle. For both components, during daytime intervals, we found evidence of power enhancements at frequencies predicted for global modes of the Earth's magnetosphere and occasionally observed at auroral latitudes in the F-region drift velocities (approximately at 1.3, 1.9, 2.6, and 3.4 mHz. Nighttime observations reveal a relative low frequency H enhancement associated with the bay occurrence together with a peak in the H/D power ratio which sharply emerges at 1.2 mHz in the premidnight sector. The strong similarity between solar minimum and maximum suggests that these modes can be considered permanent magnetospheric features. A separate analysis on a two-month interval shows that the observed spectral characteristics are amplified by conditions of high-velocity solar wind.

  1. Triggering Process of Electromagnetic Ion Cyclotron Rising Tone Emissions in the Inner Magnetosphere

    Science.gov (United States)

    Shoji, M.; Omura, Y.

    2013-12-01

    Spacecraft observations and simulations show generation of coherent electromagnetic ion cyclotron (EMIC) triggered emissions with rising-tone frequencies. In the inner magnetosphere, the spontaneously triggered EMIC waves are generated by the energetic protons with large temperature anisotropy. We reproduced EMIC triggered emissions in the Earth's magnetosphere by real scale hybrid simulations with cylindrical magnetic geometry. We obtained spontaneously triggered nonlinear EMIC waves with rising frequencies in the H+ band of the EMIC dispersion relation. The proton holes in the phase space are formed. We have also derived the theoretical optimum wave amplitude for triggering process of the EMIC nonlinear wave growth. The optimum wave amplitude and the nonlinear transition time show a good agreement with the present simulation result. The nonlinear wave growth over a limited time forms a sub-packet structure of a rising tone emission. The formation process of a sub-packet is repeated because of a new triggering wave generated by the phase-organized protons, which are released from the previous sub-packet. Then the EMIC triggered emission is formed as a train of sub-packets generated at different rising frequencies.

  2. A Mechanism for the Loading-Unloading Substorm Cycle Missing in MHD Global Magnetospheric Simulation Models

    Science.gov (United States)

    Klimas, A. J.; Uritsky, V.; Vassiliadis, D.; Baker, D. N.

    2005-01-01

    Loading and consequent unloading of magnetic flux is an essential element of the substorm cycle in Earth's magnetotail. We are unaware of an available global MHD magnetospheric simulation model that includes a loading- unloading cycle in its behavior. Given the central role that MHD models presently play in the development of our understanding of magnetospheric dynamics, and given the present plans for the central role that these models will play in ongoing space weather prediction programs, it is clear that this failure must be corrected. A 2-dimensional numerical driven current-sheet model has been developed that incorporates an idealized current- driven instability with a resistive MHD system. Under steady loading, the model exhibits a global loading- unloading cycle. The specific mechanism for producing the loading-unloading cycle will be discussed. It will be shown that scale-free avalanching of electromagnetic energy through the model, from loading to unloading, is carried by repetitive bursts of localized reconnection. Each burst leads, somewhat later, to a field configuration that is capable of exciting a reconnection burst again. This process repeats itself in an intermittent manner while the total field energy in the system falls. At the end of an unloading interval, the total field energy is reduced to well below that necessary to initiate the next unloading event and, thus, a loading-unloading cycle results. It will be shown that, in this model, it is the topology of bursty localized reconnection that is responsible for the appearance of the loading-unloading cycle.

  3. Investigation of the Magnetotail and Inner Magnetosphere with Combined Global Hybrid and CIMI Models

    Science.gov (United States)

    Lin, Y.; Wang, X.; Perez, J. D.; Fok, M. C. H.

    2014-12-01

    The interconnection between the Earth's inner and outer magnetospheric regions is calculated by coupling an existing 3-D global hybrid simulation code to an existing ring current and radiation belt code, the Comprehensive Inner Magnetosphere/Ionosphere (CIMI) model. In the hybrid simulation, the global dynamics are driven by the solar wind and a southward IMF, and the simulation domain includes the plasma regions from x=-60RE to +20RE . Evolution of the magnetotail is revealed in the hybrid simulation. The response of the ring current and radiation belts is calculated by coupling the CIMI model to the global hybrid model. The hybrid simulation results provide the CIMI model with the magnetic field and electric potential at the high-latitude ionosphere boundary and plasma density and full ion phase space distribution function at the outer boundary at the equator. Our simulation shows that the ion velocity distributions in the tail are non-Maxwellian, with the existence of multiple ion beams, which have a significant impact on the ring current and the convection electric field. Detailed results will be presented for cases with various IMF and solar wind conditions, and the simulation will be compared with satellite observations.

  4. A Globally Stable Lyapunov Pointing and Rate Controller for the Magnetospheric MultiScale Mission (MMS)

    Science.gov (United States)

    Shah, Neerav

    2011-01-01

    The Magnetospheric MultiScale Mission (MMS) is scheduled to launch in late 2014. Its primary goal is to discover the fundamental plasma physics processes of reconnection in the Earth's magnetosphere. Each of the four MMS spacecraft is spin-stabilized at a nominal rate of 3 RPM. Traditional spin-stabilized spacecraft have used a number of separate modes to control nutation, spin rate, and precession. To reduce the number of modes and simplify operations, the Delta-H control mode is designed to accomplish nutation control, spin rate control, and precession control simultaneously. A nonlinear design technique, Lyapunov's method, is used to design the Delta-H control mode. A global spin rate controller selected as the baseline controller for MMS, proved to be insufficient due to an ambiguity in the attitude. Lyapunov's design method was used to solve this ambiguity, resulting in a controller that meets the design goals. Simulation results show the advantage of the pointing and rate controller for maneuvers larger than 90 deg and provide insight into the performance of this controller.

  5. Early results on energetic particle dynamics and structure from the Energetic Ion Spectrometer (EIS) on the Magnetospheric Multiscale (MMS) mission

    Science.gov (United States)

    Cohen, I. J.; Mauk, B.; Westlake, J. H.; Anderson, B. J.; Turner, D. L.; Fennell, J. F.; Spence, H. E.; Baker, D. N.; Pollock, C. J.; Torbert, R. B.; Blake, J. B.; Sibeck, D. G.

    2015-12-01

    The cluster of four, formation-flying spacecraft, comprising the Magnetospheric Multiscale (MMS) mission, launched on 13 March 2015 into near equatorial 1.2 x 12 RE orbits, provides an important new asset for assessing the transport of energy and matter from the distant regions of Earth's magnetosphere into the inner regions. Here we report on early results from the Energetic Ion Spectrometer (EIS) instrument on each of the MMS Spacecraft. EIS provides nearly all-sky energetic ion energy, angle and elemental compositional distributions for 1 MeV. It also measures energetic electrons from 25 keV to > 0.5 MeV in support and coordination with the electron-focused Fly's Eye Energetic Particle Spectrometer (FEEPS). During the early phase of the MMS mission, while the full complement of instruments was being commissioned prior to the prime mission phase beginning 1 September 2015, EIS observed dynamic energetic particle injections at the root of the magnetotail between the post-midnight regions and dawn in association with numerous dipolarization fronts and related processes. Here we report on coordinated measurements between MMS's EIS instrument and EIS's sister instrument on the Van Allen Probes, RBSPICE, to further address the relationship between dynamic injections and depolarization fronts in the magnetotail and injections observed deep within the magnetosphere's ring current regions. We also report preliminary result on using energetic particle gradients and anistotropies to diagnose magnetopause structures near mission-identified reconnection sites.

  6. Signatures of the various regions of the outer magnetosphere in the pitch angle distributions of energetic particles

    Energy Technology Data Exchange (ETDEWEB)

    West, H.I. Jr.

    1978-12-11

    An account is given of the obervations of the pitch angle distributions of energetic particles in the near equatorial regions of the Earth's magnetosphere. The emphasis is on relating the observed distributions to the field configuration responsible for the observed effects. The observed effects relate to drift-shell splitting, to the breakdown of adiabatic guiding center motion in regions of sharp field curvature relative to partial gyro radii, to wave-particle interactions, and to moving field configurations. 39 references.

  7. A Comprehensive Model of the Near-Earth Magnetic Field. Phase 3

    Science.gov (United States)

    Sabaka, Terence J.; Olsen, Nils; Langel, Robert A.

    2000-01-01

    The near-Earth magnetic field is due to sources in Earth's core, ionosphere, magnetosphere, lithosphere, and from coupling currents between ionosphere and magnetosphere and between hemispheres. Traditionally, the main field (low degree internal field) and magnetospheric field have been modeled simultaneously, and fields from other sources modeled separately. Such a scheme, however, can introduce spurious features. A new model, designated CMP3 (Comprehensive Model: Phase 3), has been derived from quiet-time Magsat and POGO satellite measurements and observatory hourly and annual means measurements as part of an effort to coestimate fields from all of these sources. This model represents a significant advancement in the treatment of the aforementioned field sources over previous attempts, and includes an accounting for main field influences on the magnetosphere, main field and solar activity influences on the ionosphere, seasonal influences on the coupling currents, a priori characterization of ionospheric and magnetospheric influence on Earth-induced fields, and an explicit parameterization and estimation of the lithospheric field. The result of this effort is a model whose fits to the data are generally superior to previous models and whose parameter states for the various constituent sources are very reasonable.

  8. Twist-induced Magnetosphere Reconfiguration for Intermittent Pulsars

    CERN Document Server

    Huang, Lei; Tong, Hao

    2016-01-01

    We propose that the magnetosphere reconfiguration induced by magnetic twists in the closed field line region can account for the mode-switching of intermittent pulsars. We carefully investigate the properties of axisymmetric force-free pulsar magnetospheres with magnetic twists in closed field line region around the polar caps. The magnetosphere with twisted closed lines leads to enhanced spin-down rates. The enhancement in spin-down rate depends on the size of region with twisted closed lines. Typically, it is increased by a factor of $\\sim2$, which is consistent with the intermittent pulsars' spin down behavior during the `off' and `on' states. We find there is a threshold of maximal twist angle $\\Delta\\phi_{\\rm thres}\\sim1$. The magnetosphere is stable only if the closed line twist angle is less than $\\Delta\\phi_{\\rm thres}$. Beyond this value, the magnetosphere becomes unstable and gets untwisted. The spin-down rate would reduce to its off-state value. The quasi-periodicity in spin-down rate change can be...

  9. Plasma Drifts in the Intermediate Magnetosphere: Simulation Results

    Science.gov (United States)

    Lyon, J.; Zhang, B.

    2016-12-01

    One of the outstanding questions about the inner magnetosphere dynamics is how the ring current is populated. It is not clear how much is due to a general injection over longer time and spatial scales and how much due to more bursty events. One of the major uncertainties is the behavior of the plasma in the intermediate magnetosphere: the region where the magnetosphere changes from being tail-like to one where the dipole field dominates. This is also the region where physically the plasma behavior changes from MHD-like in the tail to one dominated by particle drifts in the inner magnetosphere. No of the current simulation models self-consistently handle the region where drifts are important but not dominant. We have recently developed a version of the multi-fluid LFM code that can self-consistently handle this situation. The drifts are modeled in a fashion similar to the Rice Convection Model in that a number of energy "channels" are explicitly simulated. However, the method is not limited to the "slow flow" region and both diamagnetic and inertial drifts are included. We present results from a number of idealized cases of the global magnetosphere interacting with a southward turning of the IMF. We discuss the relative importance of general convection and bursty flows to the transport of particles and energy across this region.

  10. FASTSAT-HSV01 Synergistic Observations of the Magnetospheric Response During Active Periods: MINI-ME, PISA and TTI

    Science.gov (United States)

    Casas, Joseph C.; Collier, Michael R.; Rowland, Douglas E.; Sigwarth, John B.; Boudreaux, Mark E.

    2010-01-01

    Understanding the complex processes within the inner magnetosphere of Earth particularly during storm periods requires coordinated observations of the particle and field environment using both in-situ and remote sensing techniques. In fact in order to gain a better understanding of our Heliophysics and potentially improve our space weather forecasting capabilities, new observation mission approaches and new instrument technologies which can provide both cost effective and robust regular observations of magnetospheric activity and other space weather related phenomenon are necessary. As part of the effort to demonstrate new instrument techniques and achieve necessary coordinated observation missions, NASA's Fast Affordable Science and Technology Satellite Huntsville 01 mission (FASTSAT-HSVOI) scheduled for launch in 2010 will afford a highly synergistic solution which satisfies payload mission opportunities and launch requirements as well as contributing iri the near term to our improved understanding of Heliophysics. NASA's FASTSAT-HSV01 spacecraft on the DoD Space Test Program-S26 (STP-S26) Mission is a multi-payload mission executed by the DoD Space Test Program (STP) at the Space Development and Test Wing (SDTW), Kirtland AFB, NM. and is an example of a responsive and economical breakthrough in providing new possibilities for small space technology-driven and research missions. FASTSAT-HSV is a unique spacecraft platform that can carry multiple small instruments or experiments to low-Earth orbit on a wide range of expendable launch vehicles for a fraction of the cost traditionally required for such missions. The FASTSAT-HSV01 mission allows NASA to mature and transition a technical capability to industry while increasing low-cost access to space for small science and technology (ST) payloads. The FASTSAT-HSV01 payload includes three NASA Goddard Space Flight Center (GSFC) new technology built instruments that will study the terrestrial space environment and

  11. Chaotic dynamics of corotating magnetospheric convection

    Science.gov (United States)

    Summers, Danny; Mu, Jian-Lin

    1994-01-01

    The corotating plasma convection system of the Jovian magnetosphere is analyzed. The macroscopic (mhd) model introduced by Summers and Mu, (1992) that incorporates the effects of microdiffusion is extended by including previously neglected density effects. We reduce the governing partial differential equations to a third-order ordinary differential system by the Galerkin technique of mode truncation. We carry out such a severe truncation partly in the interests of tractability, and leave open the question of the efficacy of adding additional modes. Exhaustive numerical integrations are carried out to calculate the long-term solutions, and we discover that a rich array of plasma motions is possible, dependent on the value of the height-integrated ionospheric Pederson conductivity Sigma. If Sigma is less than a certain critical value Sigma(sub c), then plasma motion can be expected to be chaotic (or periodic), while if Sigma is greater than Sigma(sub c), then steady state convection is expected. In the former case, whether the plasma motion is chaotic or periodic (and, if periodic, the magnitude of the period) can be very sensitive to the value of Sigma. The value of Sigma(sub c), which is a function of a parameter q that occurs in the assumed form of the stationary radial profile (varies as L(exp -q) of the plasma mass per unit magnetic flux, lies well within the accepted range of values of Sigma for Jupiter, i.e. Sigma greater than or equal to 0.1 mho and less than or equal to 10 mho.

  12. Prediction of Magnetospheric Disturbances Caused by a Quasi-Stationary Solar Wind

    Institute of Scientific and Technical Information of China (English)

    V. G. Eselevich; M.V. Eselevich

    2005-01-01

    When predicting parameters of quasi-stationary Solar Wind (SW) streams at 1 AU, it is customary to use, as the indicator of solar sources, the Bases of Open Magnetic Tubes (BOMT) on the solar surface obtained via a calculation relying on a new Bd-technique of harmonic expansion of the magnetic field from daily full-disk magnetograms developed by Rudenko[4]. By considering an example of 17 events, it is shown that the correspondence between fast SW streams at the Earth's orbit and the BOMT, calculated with ≤ 24 h time resolution, makes up about 94%, while the correspondence of SW stereams with the CH in the light of the 10830 A line is about 29%. With this technique, the predictability of maxima of the Kp index of magnetospheric disturbance caused by a fast quasi-stationary SW, is over 90%, and the prediction accuracy of the maximun velocity vm of the stream is ±15%.

  13. Resonant Acceleration of Magnetospheric Electrons Driven by the R-X Mode

    Institute of Scientific and Technical Information of China (English)

    XIAO Fu-Liang; ZHENG Hui-Nan; WANG Shui

    2005-01-01

    @@ An extended relativistic model is developed to evaluate the superluminous R-X-mode resonance especially the second-order and third-order resonances with electrons in the Earth's magnetosphere. The potential for stochastic electron acceleration driven by the R-X mode is determined by the dispersive properties of the R-X mode and specifically the resonant harmonic N. In contrast to the limited acceleration at the first harmonic (N = 1)resonance, for the higher harmonic (N > 1) resonances, the R-X mode is capable of accelerating electrons from ~10keV to ~ MeV energies, over a wide range of wave normal angles, in spatial regions extending from the auroral cavity to the latitude (>30°) outer radiation belt. This indicates that higher-order resonance is essentially important for the electron acceleration for the oblique wave propagation.

  14. Tracing magnetic separators and their dependence on IMF clock angle in global magnetospheric simulations

    CERN Document Server

    Komar, C M; Dorelli, J C; Glocer, A; Kuznetsova, M M

    2013-01-01

    A new, efficient, and highly accurate method for tracing magnetic separators in global magnetospheric simulations with arbitrary clock angle is presented. The technique is to begin at a magnetic null and iteratively march along the separator by finding where four magnetic topologies meet on a spherical surface. The technique is verified using exact solutions for separators resulting from an analytic magnetic field model that superposes dipolar and uniform magnetic fields. Global resistive magnetohydrodynamic simulations are performed using the three-dimensional BATS-R-US code with a uniform resistivity, in eight distinct simulations with interplanetary magnetic field (IMF) clock angles ranging from 0 (parallel) to 180 degrees (anti-parallel). Magnetic nulls and separators are found in the simulations, and it is shown that separators traced here are accurate for any clock angle, unlike the last closed field line on the Sun-Earth line that fails for southward IMF. Trends in magnetic null locations and the struc...

  15. Results of the Apogee-Raising Campaign of the Magnetospheric Multiscale Mission

    Science.gov (United States)

    Williams, Trevor; Ottenstein, Neil; Palmer, Eric J.; Hollister, Jacob

    2017-01-01

    This paper describes the apogee-raising campaign of the Magnetospheric Multiscale mission, where the spacecraft increased their apogee radii from 12 to 25 Earth radii in a total of 98 maneuvers. These maneuvers included an initial formation resize set to spread the spacecraft apart for safety, 32 apogee-raise delta-v maneuvers, their associated slews, four perigee-raise maneuvers and the associated slews, and finally a set of maneuvers to get back into formation. These activities were all accomplished successfully and on schedule with no anomalies, and at a fuel consumption somewhat less than predicted. As a result, MMS was set up ready to carry out in situ studies of magnetic reconnection in the magnetotail, with sufficient fuel remaining for a significant extended mission.

  16. Transport of cosmic rays in magnetosphere and heliosphere: GeoMag and HelMod webmodels

    Science.gov (United States)

    Bobik, P.; Boschini, M. J.; Della Torre, S.; Gervasi, M.; Grandi, D.; Kudela, K.; La Vacca, G.; Mallamaci, M.; Pensotti, S.; Putis, M.; Rancoita, P. G.; Rozza, D.; Tacconi, M.

    2014-06-01

    Our codes to evaluate the solar modulation of Galactic Cosmic Rays (HelMod) and to trace the the charged particles inside the Earth magnetosphere (GeoMag) have been implemented as webmodels in the two websites, helmod.org and geomagsphere.org. HelMod model uses a 2D Monte Carlo approach to solves the Parker transport equation, obtaining a modulated flux of Cosmic Rays for a period starting from 1990. We implemented a web interface to get a catalog of: 1) proton energy spectra at a fixed time, and 2) time modulated flux at a fixed energy. A beta-version of HelMod for more complex simulations of protons, antiprotons, electrons and positrons, at any distance from the Sun is also available to the users. The GeoMag back-tracing code reconstructs the charged particle trajectories in the Earth Magnetosphere back in time. We use the last models of internal (IGRF-11) and external (Tsyganenko 1996 -T96- and 2005 -T05-) field components valid up to 2015. The user can get the vertical rigidity cutoff estimation obtained with the backtracing technique and the asymptotic coordinates and directions for several rigidities at a fixed position and date, starting from Jan. 1st, 1968 (for T96) and Jan. 1st, 1995 (for T05) respectively till 31st Dec 2012. The website geomagsphere.org reports, in addition, a list of the most intense solar flares registered by several observatories in space, starting from January 2011, together with the evaluation of the dynamic pressure of solar energetic particles, related to the major solar events occurred in the same period.

  17. Aspects of magnetosphere-ionosphere coupling in sawtooth substorms: a case study

    Science.gov (United States)

    Sandholt, P. E.; Farrugia, C. J.

    2014-10-01

    In a case study we report on repetitive substorm activity during storm time which was excited during Earth passage of an interplanetary coronal mass ejection (ICME) on 18 August 2003. Applying a combination of magnetosphere and ground observations during a favourable multi-spacecraft configuration in the plasma sheet (GOES-10 at geostationary altitude) and in the tail lobes (Geotail and Cluster-1), we monitor the temporal-spatial evolution of basic elements of the substorm current system. Emphasis is placed on activations of the large-scale substorm current wedge (SCW), spanning the 21:00-03:00 MLT sector of the near-Earth plasma sheet (GOES-10 data during the interval 06:00-12:00 UT), and magnetic perturbations in the tail lobes in relation to ground observations of auroral electrojets and convection in the polar cap ionosphere. The joint ground-satellite observations are interpreted in terms of sequential intensifications and expansions of the outer and inner current loops of the SCW and their respective associations with the westward electrojet centred near midnight (24:00 MLT) and the eastward electrojet observed at 14:00-15:00 MLT. Combined magnetic field observations across the tail lobe from Cluster and Geotail allow us to make estimates of enhancements of the cross-polar-cap potential (CPCP) amounting to ≈ 30-60 kV (lower limits), corresponding to monotonic increases of the PCN index by 1.5 to 3 mV m-1 from inductive electric field coupling in the magnetosphere-ionosphere (M-I) system during the initial transient phase of the substorm expansion.

  18. MHD Simulations of Magnetospheric Accretion, Ejection and Plasma-field Interaction

    Directory of Open Access Journals (Sweden)

    Romanova M. M.

    2014-01-01

    Full Text Available We review recent axisymmetric and three-dimensional (3D magnetohydrodynamic (MHD numerical simulations of magnetospheric accretion, plasma-field interaction and outflows from the disk-magnetosphere boundary.

  19. 3-D Magnetospheric Field and Plasma Containing Thin Current Sheets

    Science.gov (United States)

    Zaharia, S.; Cheng, C. Z.; Maezawa, K.; Wing, S.

    2002-05-01

    In this study we present fully-3D self-consistent solutions of the magnetosphere by using observation-based plasma pressure distributions and computational boundary conditions based on the T96 magnetospheric field model. The pressure profiles we use are either taken directly from observations (GEOTAIL pressure data in the plasma sheet and DMSP ionospheric pressure) or empirical (Spence-Kivelson formula for pressure on the midnight equatorial line). The 3-D solutions involve solving 2 coupled elliptic equations in a flux coordinate systems, with the magnetic field expressed by two Euler potentials and using appropriate boundary conditions for both the closed- and open-field regions derived from the empirical field model. We look into how the self-consistent magnetic field and current structures change under different external conditions, and we discuss the appearance of thin cross-tail current sheets during disturbed magnetospheric times.

  20. Magnetospheric Cavity Modes Driven by Solar Wind Dynamic Pressure Fluctuations

    CERN Document Server

    Claudepierre, S G; Elkington, S R; Lotko, W; Hudson, M K; 10.1029/2009GL039045

    2010-01-01

    We present results from Lyon-Fedder-Mobarry (LFM) global, three-dimensional magnetohydrodynamic (MHD) simulations of the solar wind-magnetosphere interaction. We use these simulations to investigate the role that solar wind dynamic pressure fluctuations play in the generation of magnetospheric ultra-low frequency (ULF) pulsations. The simulations presented in this study are driven with idealized solar wind input conditions. In four of the simulations, we introduce monochromatic ULF fluctuations in the upstream solar wind dynamic pressure. In the fifth simulation, we introduce a continuum of ULF frequencies in the upstream solar wind dynamic pressure fluctuations. In this numerical experiment, the idealized nature of the solar wind driving conditions allows us to study the magnetospheric response to only a fluctuating upstream dynamic pressure, while holding all other solar wind driving parameters constant. The simulation results suggest that ULF fluctuations in the solar wind dynamic pressure can drive magnet...

  1. Magnetic Structure of the Magnetopause Boundary Layer for Open Magnetosphere

    Science.gov (United States)

    Ma, Yonghui; Shen, Chao; Zeng, Gang

    2017-04-01

    Using Cluster and Magnetospheric MultiScale (MMS) spacecraft 4 point magnetic field measurements, we analyzed the magnetic structure of magnetopause boundary layer of the open magnetosphere. It is indicated that the magnetopause boundary layer is very thin under strong magnetic shear and the thickness is usually 0.1 Re. We found that the Rotational Discontinuity (RD) is very important structure at magnetopause when the Interplanetary Magnetic Field (IMF) is southward. Within the boundary layer, the magnetic field has a large rotation. Using curvature calculation method, we got that the minimum curvature radius of magnetic field of RD is 0.02 - 0.1Re, implying that the magnetosphere is open when the IMF is southward. Advanced research showed that the field-aligned currents are common in the magnetopause boundary layer.

  2. HLL Riemann Solvers and Alfven Waves in Black Hole Magnetospheres

    CERN Document Server

    Punsly, Brian; Kim, Jinho; Garain, Sudip

    2016-01-01

    In the magnetosphere of a rotating black hole, an inner Alfven critical surface (IACS) must be crossed by inflowing plasma. Inside the IACS, Alfven waves are inward directed toward the black hole. The majority of the proper volume of the active region of spacetime (the ergosphere) is inside of the IACS. The charge and the totally transverse momentum flux (the momentum flux transverse to both the wave normal and the unperturbed magnetic field) are both determined exclusively by the Alfven polarization. However, numerical simulations of black hole magnetospheres are often based on 1-D HLL Riemann solvers that readily dissipate Alfven waves. Elements of the dissipated wave emerge in adjacent cells regardless of the IACS, there is no mechanism to prevent Alfvenic information from crossing outward. Thus, it is unclear how simulated magnetospheres attain the substantial Goldreich-Julian charge density associated with the rotating magnetic field. The HLL Riemann solver is also notorious for producing large recurring...

  3. Hybrid simulations of mini-magnetospheres in the laboratory

    CERN Document Server

    Gargaté, L; Fonseca, R A; Bamford, R; Thornton, A; Gibson, K; Bradford, J; Silva, L O

    2008-01-01

    Solar energetic ions are a known hazard to both spacecraft electronics and to manned space flights in interplanetary space missions that extend over a long period of time. A dipole-like magnetic field and a plasma source, forming a mini magnetosphere, are being tested in the laboratory as means of protection against such hazards. We investigate, via particle-in-cell hybrid simulations, using kinetic ions and fluid electrons, the characteristics of the mini magnetospheres. Our results, for parameters identical to the experimental conditions, reveal the formation of a mini-magnetosphere, whose features are scanned with respect to the plasma density, the plasma flow velocity, and the intensity of the dipole field. Comparisons with a simplified theoretical model reveal a good qualitative agreement and excellent quantitative agreement for higher plasma dynamic pressures and lower B-fields.

  4. RCM simulation of interchange transport in Saturn's inner magnetosphere

    Science.gov (United States)

    Hill, T. W.; Liu, X.; Sazykin, S. Y.; Wolf, R.

    2013-12-01

    Numerical simulations with the Rice Convection Model have been used to study the radial transport of plasma in Saturn's inner magnetosphere (L process is the pervasive presence of V-shaped injection/dispersion signatures in linear energy-time spectrograms that are observed by the Cassini Plasma Spectrometer (CAPS) on every pass through the inner magnetosphere. Using observed hot plasma distributions at L~12 as input, we have now successfully simulated these V-shaped signatures. We will show these simulation results and compare them with observed signatures. We will also describe future improvements to the model including relaxing the dipole-field assumption, thus enabling us to simulate local-time asymmetries imposed by the outer magnetosphere and tail.

  5. Electromagnetic ion cyclotron waves stimulated by modest magnetospheric compressions

    Science.gov (United States)

    Anderson, B. J.; Hamilton, D. C.

    1993-01-01

    AMPTE/CCE magnetic field and particle data are used to test the suggestion that increased hot proton temperature anisotropy resulting from convection during magnetospheric compression is responsible for the enhancement in Pc 1 emission via generation of electromagnetic ion cyclotron (EMIC) waves in the dayside outer equatorial magnetosphere. The relative increase in magnetic field is used to gauge the strength of the compression, and an image dipole model is used to estimate the motion of the plasma during compression. Proton data are used to analyze the evolution of the proton distribution and the corresponding changes in EMIC wave activity expected during the compression. It is suggested that enhancements in dynamic pressure pump the energetic proton distributions in the outer magnetosphere, driving EMIC waves. Waves are expected to be generated most readily close to the magnetopause, and transient pressure pulses may be associated with bursts of EMIC waves, which would be observed on the ground in association with ionospheric transient signatures.

  6. Sun, Earth and Sky

    Science.gov (United States)

    Lang, Kenneth R.

    1995-01-01

    The Sun is enveloped by a hot, tenuous million-degree corona that expands to create a continuous solar wind that sweeps past all the planets and fills the heliosphere. The solar wind is modulated by strong gusts that are initiated by powerful explosions on the Sun, including solar flares and coronal mass ejections. This dynamic, invisible outer atmosphere of the Sun is currently under observation with the soft X-ray telescope aboard the Yohkoh spacecraft, whose results are presented. We also show observations from the Ulysses spacecraft that is now passing over the solar pole, sampling the solar wind in this region for the first time. Two other spacecraft, Voyager 1 and 2, have recently detected the outer edge of the invisible heliosphere, roughly halfway to the nearest star. Magnetic solar activity, the total radiative output from the Sun, and the Earth's mean global surface temperature all vary with the 11-year sunspot cycle in which the total number of sunspots varies from a maximum to a minimum and back to a maximum again in about 11 years. The terrestrial magnetic field hollows out a protective magnetic cavity, called the magnetosphere, within the solar wind. This protection is incomplete, however, so the Sun feeds an unseen world of high-speed particles and magnetic fields that encircle the Earth in space. These particles endanger spacecraft and astronauts, and also produce terrestrial aurorae. An international flotilla of spacecraft is now sampling the weak points in this magnetic defense. Similar spacecraft have also discovered a new radiation belt, in addition to the familiar Van Allen belts, except fed by interstellar ions instead of electrons and protons from the Sun.

  7. Multifluid Block-Adaptive-Tree Solar Wind Roe-Type Upwind Scheme: Magnetospheric Composition and Dynamics During Geomagnetic Storms-Initial Results

    Science.gov (United States)

    Glocer, A.; Toth, G.; Ma, Y.; Gombosi, T.; Zhang, J.-C.; Kistler, L. M.

    2009-01-01

    The magnetosphere contains a significant amount of ionospheric O+, particularly during geomagnetically active times. The presence of ionospheric plasma in the magnetosphere has a notable impact on magnetospheric composition and processes. We present a new multifluid MHD version of the Block-Adaptive-Tree Solar wind Roe-type Upwind Scheme model of the magnetosphere to track the fate and consequences of ionospheric outflow. The multifluid MHD equations are presented as are the novel techniques for overcoming the formidable challenges associated with solving them. Our new model is then applied to the May 4, 1998 and March 31, 2001 geomagnetic storms. The results are juxtaposed with traditional single-fluid MHD and multispecies MHD simulations from a previous study, thereby allowing us to assess the benefits of using a more complex model with additional physics. We find that our multifluid MHD model (with outflow) gives comparable results to the multispecies MHD model (with outflow), including a more strongly negative Dst, reduced CPCP, and a drastically improved magnetic field at geosynchronous orbit, as compared to single-fluid MHD with no outflow. Significant differences in composition and magnetic field are found between the multispecies and multifluid approach further away from the Earth. We further demonstrate the ability to explore pressure and bulk velocity differences between H+ and O+, which is not possible when utilizing the other techniques considered

  8. Multi-Fluid Block-Adaptive-Tree Solar Wind Roe-Type Upwind Scheme: Magnetospheric Composition and Dynamics During Geomagnetic Storms, Initial Results

    Science.gov (United States)

    Gkocer, A.; Toth, G.; Ma, Y.; Gombosi, T.; Zhang, J. C.; Kistler, L. M.

    2010-01-01

    The magnetosphere contains a significant amount of ionospheric O{+}, particularly during geomagnetically active times. The presence of ionospheric plasma in the magnetosphere has a notable impact on magnetospheric composition and processes. We present a new multifluid MHD version of the BATS-R-US model of the magnetosphere to track the fate and consequences of ionospheric outflow. The multi-fluid MHD equations are presented as are the novel techniques for overcoming the formidable challenges associated with solving them. Our new model is then applied to the May 4, 1998 and March 31, 2001 geomagnetic storms. The results are juxtaposed with traditional single- fluid MHD and multispecies MHD simulations from a previous study, thereby allowing us to assess the benefits of using a more complex model with additional physics. We find that our multi-fluid MHD model (with outflow) gives comparable results to the multi-species MHD model (with outflow), including a more strongly negative Dst, reduced CPCP, and a drastically improved magnetic field at geosynchronous orbit, as compared to single-fluid MHD with no outflow. Significant differences in composition and magnetic field are found between the multi-species and multi-fluid approach further away from the Earth. We further demonstrate the ability to explore pressure and bulk velocity differences between H{+} and O(+}, which is not possible when utilizing the other techniques considered.

  9. Multifluid Block-Adaptive-Tree Solar Wind Roe-Type Upwind Scheme: Magnetospheric Composition and Dynamics During Geomagnetic Storms-Initial Results

    Science.gov (United States)

    Glocer, A.; Toth, G.; Ma, Y.; Gombosi, T.; Zhang, J.-C.; Kistler, L. M.

    2009-01-01

    The magnetosphere contains a significant amount of ionospheric O+, particularly during geomagnetically active times. The presence of ionospheric plasma in the magnetosphere has a notable impact on magnetospheric composition and processes. We present a new multifluid MHD version of the Block-Adaptive-Tree Solar wind Roe-type Upwind Scheme model of the magnetosphere to track the fate and consequences of ionospheric outflow. The multifluid MHD equations are presented as are the novel techniques for overcoming the formidable challenges associated with solving them. Our new model is then applied to the May 4, 1998 and March 31, 2001 geomagnetic storms. The results are juxtaposed with traditional single-fluid MHD and multispecies MHD simulations from a previous study, thereby allowing us to assess the benefits of using a more complex model with additional physics. We find that our multifluid MHD model (with outflow) gives comparable results to the multispecies MHD model (with outflow), including a more strongly negative Dst, reduced CPCP, and a drastically improved magnetic field at geosynchronous orbit, as compared to single-fluid MHD with no outflow. Significant differences in composition and magnetic field are found between the multispecies and multifluid approach further away from the Earth. We further demonstrate the ability to explore pressure and bulk velocity differences between H+ and O+, which is not possible when utilizing the other techniques considered

  10. On the origins of energetic ions in the earth's dayside magnetosheath

    Science.gov (United States)

    Fuselier, S. A.; Klumpar, D. M.; Shelley, E. G.

    1991-01-01

    Energetic ion events in the earth's dayside subsolar magnetosheath (0900 - 1300 Local Time) are surveyed using data from the AMPTE/CCE Hot Plasma Composition Experiment. Ion species carrying the signature of their origin O(+) and energetic He(2+) are used to distinguish between magnetospheric and solar wind origins for the energetic ion events. The results of this survey indicate that the majority of energetic (10-17 keV/e) H(+) and He(2+) ions observed in the dayside magnetosheath are accelerated from the solar wind population. The energetic He(2+) to H(+) density ratio in the magnetosheath is consistent with that predicted from first-order Fermi acceleration of solar wind ions in the turbulent regions upstream and downstream from the earth's quasi-parallel bow shock. The simultaneous occurrence of both energetic He(2+) and magnetospheric O(+) indicates that, on occasion, both Fermi acceleration of solar wind ions and leakage of magnetospheric ions occurs in the dayside magnetosheath.

  11. Multi-Scale Physical Process in the Magnetosphere

    Institute of Scientific and Technical Information of China (English)

    CAO Jinbin; LIU Zhenxing

    2008-01-01

    The brief report presents a part of the research results of the magnetospheric physics researches in China during the period of 2006--2008.During the past two years,China-ESA cooperation DSP(Double Star Program)satellites were basically operating normally in its extended lifetime.The DSP and Cluster missions provide Chinese space physicists high quality data to study multi-scale physical process in the magnetosphere.The work made based on the data of DSP is presented in the paper of"Progress of Double Star Program"of this issue.

  12. Magnetospheric Physics in China During the Period of 2004 - 2006

    Institute of Scientific and Technical Information of China (English)

    CAO Jinbin; LIU Zhenxing

    2006-01-01

    Their brief report presents the advances of the magnetospheric physics researches in China during the period of 2004-2006. During the past two years, China-ESA cooperation DSP (Double Star Program) satellites were successively launched. In addition, China also participated in the scientific research of ESA's Cluster mission. The DSP and Cluster missions provide Chinese space physicists high quality data to study multiscale physical process in the magnetosphere. The work made based on the data of DSP is presented in the paper of "Progress of Double Star Program" of this issue.

  13. Numerical simulation of oscillating magnetospheres with resistive electrodynamics

    CERN Document Server

    Kojima, Yasufumi

    2014-01-01

    We present a model of the magnetosphere around an oscillating neutron star. The electromagnetic fields are numerically solved by modeling electric charge and current induced by the stellar torsional mode, with particular emphasis on outgoing radiation passing through the magnetosphere. The current is modeled using Ohm's law, whereby an increase in conductivity results in an increase in the induced current. As a result, the fields are drastically modified, and energy flux is thereby enhanced. This behavior is however localized in the vicinity of the surface since the induced current disappears outwardly in our model, in which the exterior is assumed to gradually approach a vacuum.

  14. Null fields in the outer Jovian magnetosphere: Ulysses observations

    Science.gov (United States)

    Haynes, P. L.; Balogh, A.; Dougherty, M. K.; Southwood, D. J.; Fazakerley, A.; Smith, E. J.

    1994-01-01

    This paper reports on a magnetic field phenomenon, hereafter referred to as null fields, which were discovered during the inbound pass of the recent flyby of Jupiter by the Ulysses spacecraft. These null fields which were observed in the outer dayside magnetosphere are characterised by brief but sharp decreases of the field magnitude to values less than 1 nT. The nulls are distinguished from the current sheet signatures characteristic of the middle magnetosphere by the fact that the field does not reverse across the event. A field configuration is suggested that accounts for the observed features of the events.

  15. Earth\\'s Mass Variability

    CERN Document Server

    Mawad, Ramy

    2014-01-01

    The perturbation of the Earth caused by variability of mass of Earth as additional reason with gravity of celestial bodies and shape of the Earth. The Earth eating and collecting matters from space and loss or eject matters to space through its flying in the space around the Sun. The source of the rising in the global sea level is not closed in global warming and icebergs, but the outer space is the additional important source for this rising. The Earth eats waters from space in unknown mechanism. The mass of the Earth become greater in November i.e. before transit apoapsis two months, and become latter in February i.e. after transit apoapsis to two months.

  16. Pressure-Balance Consistency in Magnetospheric Modelling

    Institute of Scientific and Technical Information of China (English)

    肖永登; 陈出新

    2003-01-01

    There have been many magnetic field models for geophysical and astrophysical bodies.These theoretical or empirical models represent the reality very well in some cases,but in other cases they may be far from reality.We argue that these models will become more reasonable if they are modified by some coordinate transformations.In order to demonstrate the transformation,we use this method to resolve the "pressure-balance inconsistency"problem that occurs when plasma transports from the outer plasma sheet of the Earth into the inner plasma sheet.

  17. Correlations and linkages between the sun and the earth's atmosphere: Needed measurements and observations

    Science.gov (United States)

    Kellogg, W. W.

    1975-01-01

    A study was conducted to identify the sequence of processes that lead from some change in solar input to the earth to a change in tropospheric circulation and weather. Topics discussed include: inputs from the sun, the solar wind, and the magnetosphere; bremsstrahlung, ionizing radiation, cirrus clouds, thunderstorms, wave propagation, and gravity waves.

  18. Magnetospheric ';magic' frequencies excited by subsolar magnetosheath jets

    Science.gov (United States)

    Archer, M. O.; Hartinger, M.; Horbury, T. S.

    2013-12-01

    Statistical and event studies have shown that magnetospheric ULF waves are often observed at persistent discrete Pc5 frequencies known as ';magic' frequencies [see Menk 2011 for a recent review]. While typically assumed to be global (cavity/waveguide) modes, another interpretation is that of magnetopause surface eigenmodes, which may be excited by localised pressure enhancements in the magnetosheath. To distinguish between these hypotheses, we identify transient jets in the magnetosheath (which occur about 2% of the time, predominantly downstream of the quasi-parallel shock) and statistically investigate the spectral response of the magnetospheric magnetic field at geostationary orbit. The broadband jets do indeed excite waves at the ';magic' frequencies, with both direct and resonant driving. We show that the expected fundamental frequencies of magnetopause surface eigenmodes have two preferential values over a wide range of upstream conditions, corresponding to fast and slow solar wind, and that their harmonics are in good agreement with the ';magic' frequencies. We also show that the waves are largely inconsistent with global (cavity/waveguide) modes outside the plasmasphere. Thus we conclude that the ';magic' frequencies are most likely due to magnetopause surface eigenmodes. Menk, F. W., Magnetospheric ULF waves: A review, in The dynamic magnetosphere, edited by W. Lui and M. Fujimoto, IAGA Special Sopron Book Series, pp. 223-256, Springer-Verlag Berlin, doi:10.1007/978-94-007-0501-2_13, 2011.

  19. Probing magnetars magnetosphere through X-ray polarization measurements

    CERN Document Server

    Taverna, Roberto; Turolla, Roberto; Soffitta, Paolo; Fabiani, Sergio; Nobili, Luciano

    2013-01-01

    The study of magnetars is of particular relevance since these objects are the only laboratories where the physics in ultra-strong magnetic fields can be directly tested. Until now, spectroscopic and timing measurements at X-ray energies in soft gamma-repeaters (SGRs) and anomalous X-ray pulsar (AXPs) have been the main source of information about the physical properties of a magnetar and of its magnetosphere. Spectral fitting in the ~ 0.5-10 keV range allowed to validate the "twisted magnetosphere" model, probing the structure of the external field and estimating the density and velocity of the magnetospheric currents. Spectroscopy alone, however, may fail in disambiguating the two key parameters governing magnetospheric scattering (the charge velocity and the twist angle) and is quite insensitive to the source geometry. X-ray polarimetry, on the other hand, can provide a quantum leap in the field by adding two extra observables, the linear polarization degree and the polarization angle. Using the bright AXP ...

  20. Plasma Density and Radio Echoes in the Magnetosphere

    Science.gov (United States)

    Calvert, W.

    1995-01-01

    This project provided a opportunity to study a variety of interesting topics related to radio sounding in the magnetosphere. The results of this study are reported in two papers which have been submitted for publication in the Journal of Geophysical Research and Radio Science, and various aspects of this study were also reported at meetings of the American Geophysical Union (AGU) at Baltimore, Maryland and the International Scientific Radio Union (URSI) at Boulder, Colorado. The major results of this study were also summarized during a one-day symposium on this topic sponsored by Marshall Space Flight Center in December 1994. The purpose of the study was to examine the density structure of the plasmasphere and determine the relevant mechanisms for producing radio echoes which can be detected by a radio sounder in the magnetosphere. Under this study we have examined density irregularities, biteouts, and outliers of the plasmasphere, studied focusing, specular reflection, ducting, and scattering by the density structures expected to occur in the magnetosphere, and predicted the echoes which can be detected by a magnetospheric radio sounder.

  1. Quasiperiodic ULF-pulsations in Saturn's magnetosphere

    Directory of Open Access Journals (Sweden)

    G. Kleindienst

    2009-02-01

    Full Text Available Recent magnetic field investigations made onboard the Cassini spacecraft in the magnetosphere of Saturn show the existence of a variety of ultra low frequency plasma waves. Their frequencies suggest that they are presumably not eigenoscillations of the entire magnetospheric system, but excitations confined to selected regions of the magnetosphere. While the main magnetic field of Saturn shows a distinct large scale modulation of approximately 2 nT with a periodicity close to Saturn's rotation period, these ULF pulsations are less obvious superimposed oscillations with an amplitude generally not larger than 3 nT and show a package-like structure. We have analyzed these wave packages and found that they are correlated to a certain extent with the large scale modulation of the main magnetic field. The spatial localization of the ULF wave activity is represented with respect to local time and Kronographic coordinates. For this purpose we introduce a method to correct the Kronographic longitude with respect to a rotation period different from its IAU definition. The observed wave packages occur in all magnetospheric regions independent of local time, elevation, or radial distance. Independent of the longitude correction applied the wave packages do not occur in an accentuated Kronographic longitude range, which implies that the waves are not excited or confined in the same selected longitude ranges at all times or that their lifetime leads to a variable phase with respect to the longitudes where they have been exited.

  2. Laboratory simulation of energetic flows of magnetospheric planetary plasma

    Science.gov (United States)

    Shaikhislamov, I. F.; Posukh, V. G.; Melekhov, A. V.; Boyarintsev, E. L.; Zakharov, Yu P.; Prokopov, P. A.; Ponomarenko, A. G.

    2017-01-01

    Dynamic interaction of super-sonic counter-streaming plasmas moving in dipole magnetic dipole is studied in laboratory experiment. First, a quasi-stationary flow is produced by plasma gun which forms a magnetosphere around the magnetic dipole. Second, explosive plasma expanding from inner dipole region outward is launch by laser beams focused at the surface of the dipole cover. Laser plasma is energetic enough to disrupt magnetic field and to sweep through the background plasma for large distances. Probe measurements showed that far from the initially formed magnetosphere laser plasma carries within itself a magnetic field of the same direction but order of magnitude larger in value than the vacuum dipole field at considered distances. Because no compression of magnetic field at the front of laser plasma was observed, the realized interaction is different from previous experiments and theoretical models of laser plasma expansion into uniform magnetized background. It was deduced based on the obtained data that laser plasma while expanding through inner magnetosphere picks up a magnetized shell formed by background plasma and carries it for large distances beyond previously existing magnetosphere.

  3. Probing magnetar magnetosphere through X-ray polarization measurements

    Science.gov (United States)

    Taverna, R.; Muleri, F.; Turolla, R.; Soffitta, P.; Fabiani, S.; Nobili, L.

    2014-02-01

    The study of magnetars is of particular relevance since these objects are the only laboratories where the physics in ultra-strong magnetic fields can be directly tested. Until now, spectroscopic and timing measurements at X-ray energies in soft gamma repeaters and anomalous X-ray pulsars (AXPs) have been the main source of information about the physical properties of a magnetar and of its magnetosphere. Spectral fitting in the ˜0.5-10 keV range allowed us to validate the `twisted magnetosphere' model, probing the structure of the external field and estimating the density and velocity of the magnetospheric currents. Spectroscopy alone, however, may fail in disambiguating the two key parameters governing magnetospheric scattering (the charge velocity and the twist angle) and is quite insensitive to the source geometry. X-ray polarimetry, on the other hand, can provide a quantum leap in the field by adding two extra observables, the linear polarization degree and the polarization angle. Using the bright AXP 1RXS J170849.0-400910 as a template, we show that phase-resolved polarimetric measurements can unambiguously determine the model parameters, even with a small X-ray polarimetry mission carrying modern photoelectric detectors and existing X-ray optics. We also show that polarimetric measurements can pinpoint vacuum polarization effects and thus provide indirect evidence for ultra-strong magnetic fields.

  4. Magnetospheres of hot Jupiters: hydrodynamic models & ultraviolet absorption

    CERN Document Server

    Alexander, R D; Mohammed, H; Nichols, J D; Ercolano, B

    2015-01-01

    We present hydrodynamic simulations of stellar wind-magnetosphere interactions in hot Jupiters such as WASP-12b. For fiducial stellar wind rates we find that a planetary magnetic field of a few G produces a large magnetospheric cavity, which is typically 6-9 planetary radii in size. A bow shock invariably forms ahead of the magnetosphere, but the pre-shock gas is only mildly supersonic (with typical Mach numbers of $\\simeq$1.6-1.8) so the shock is weak. This results in a characteristic signature in the ultraviolet light curve: a broad absorption feature that leads the optical transit by 10-20% in orbital phase. The shapes of our synthetic light-curves are consistent with existing observations of WASP-12b, but the required near-UV optical depth ($\\tau \\sim 0.1$) can only be achieved if the shocked gas cools rapidly. We further show that radiative cooling is inefficient, so we deem it unlikely that a magnetospheric bow shock is responsible for the observed near-UV absorption. Finally, we apply our model to two ...

  5. The electron density of Saturn's magnetosphere

    Directory of Open Access Journals (Sweden)

    M. W. Morooka

    2009-07-01

    Full Text Available We have investigated statistically the electron density below 5 cm−3 in the magnetosphere of Saturn (7–80 RS, Saturn radii using 44 orbits of the floating potential data from the RPWS Langmuir probe (LP onboard Cassini. The density distribution shows a clear dependence on the distance from the Saturnian rotation axis (√X2+Y2 as well as on the distance from the equatorial plane (|Z|, indicating a disc-like structure. From the characteristics of the density distribution, we have identified three regions: the extension of the plasma disc, the magnetodisc region, and the lobe regions. The plasma disc region is at L<15, where L is the radial distance to the equatorial crossing of the dipole magnetic field line, and confined to |Z|<5 RS. The magnetodisc is located beyond L=15, and its density has a large variability. The variability has quasi-periodic characteristics with a periodicity corresponding to the planetary rotation. For Z>15 RS, the magnetospheric density distribution becomes constant in Z. However, the density still varies quasi-periodically with the planetary rotation also in this region. In fact, the quasi-periodic variation has been observed all over the magnetosphere beyond L=15. The region above Z=15 RS is identified as the lobe region. We also found that the magnetosphere can occasionally move latitudinally under the control of the density in the magnetosphere and the solar wind. From the empirical distributions of the electron densities obtained in this study, we have constructed an electron density model of the Saturnian nightside magnetosphere beyond 7 RS. The obtained model can well reproduce the observed density distribution, and can thus be useful for magnetospheric modelling studies.

  6. Magnetospheres of Planets and Moons: Links to Their Ionospheres. (Invited)

    Science.gov (United States)

    Kivelson, M. G.

    2010-12-01

    The phrase “magnetosphere-ionosphere coupling” has become almost hackneyed in the terrestrial context, but plays an important role in the terrestrial system and must also be emphasized in the context of planetary- and moon-magnetospheres because the underlying principles are similar in all systems. This talk will introduce only two intriguing aspects of the coupling problem for planets and moons. In describing the first topic, we note that, especially for the gas giants Jupiter and Saturn, much of the evidence of magnetosphere-ionosphere coupling is obtained from auroral imaging. In images of Jupiter’s polar ionosphere, bright auroral spots are found to link magnetically to the moons Io, Europa and Ganymede. The spots give evidence of intense field-aligned currents generated near the equator in the interaction between the moons and the flowing plasma of Jupiter’s magnetosphere. The currents must penetrate through regions of impedance mismatch near the upper and lower boundaries of Jupiter’s equatorial plasma torus in order to close in the planetary ionosphere. There is some evidence that the signal propagates through the strong gradient of plasma density at the boundary of the plasma torus by converting into a striated structure that guides high frequency waves. As well, at Io, the interaction has been found to generate localized intense electron fluxes observed to flow along and antiparallel to the magnetic field near the equator. These bidirectional beams are probably accelerated by parallel electric fields near the ionospheric ends of the flux tube, but how the accelerated electrons reach the equator has not been explained. It seems likely that their presence there requires that the (parallel) electric fields in the Jovian ionosphere vary either temporally at high frequency or spatially on short transverse length scales. The full explanation has not yet been developed. As a second example of the role of magnetosphere-ionosphere coupling in planetary

  7. On the origins of energetic ions in the Earth's dayside magnetosheath

    Energy Technology Data Exchange (ETDEWEB)

    Fuselier, S.A.; Klumpar, D.M.; Shelley, E.G. (Lockheed Palo Alto Research Lab., CA (USA))

    1991-01-01

    Energetic ion events in the Earth's dayside subsolar magnetosheath (0900 - 1300 Local Time) are surveyed using data from the Active Magnetospheric Particle Tracer Explorers/Charge Composition Explorer (AMPTE/CCE) Hot Plasma Composition Experiment. Ion species carrying the signature of their origin (O{sup +} and energetic He{sup 2+}) are used to distinguish between magnetospheric and solar wind orgins for the energetic ion events. The results of this survey indicate that the majority of energetic (10-17 keV/e) H{sup +} and He{sup 2+} ions observed in the dayside magnetosheath are accelerated from the solar wind population. The energetic He{sup 2+} to H{sup +} density ratio in the magnetosheath is consistent with that predicted from first-order Fermi acceleration of solar wind ions in the turbulent regions upstream and downstream from the Earth's quasi-parallel bow shock. Although the majority of the energetic ions appear to be of solar wind origin, magnetospheric O{sup +} is also occasionally present in the magnetosheath. The simultaneous occurence of both energetic He{sup 2+} and magnetospheric O{sup +} indicates that, on occasion, both Fermi acceleration of solar wind ions and leakage of magnetospheric ions occurs in the dayside magnetosheath.

  8. Earth Orbit Raise Design for the Artemis Mission

    Science.gov (United States)

    Wiffen, Gregory J.; Sweetser, Theodore H.

    2011-01-01

    The Artemis mission is an extension of the Themis mission. The Themis mission1 consisted of five identical spacecraft in varying sized Earth orbits designed to make simultaneous measurements of the Earth's electric and magnetic environment. Themis was designed to observe geomagnetic storms resulting from solar wind's interaction with the Earth's magnetosphere. Themis was meant to answer the age old question of why the Earth's aurora can change rapidly on a global scale. The Themis spacecraft are spin stabilized with 20 meter long electric field booms as well as several shorter magnetometer booms. The goal of the Artemis2 mission extension is to deliver the field and particle measuring capabilities of two of the Themis spacecraft to the vicinity of the Moon. The Artemis mission required transferring two Earth orbiting Themis spacecraft on to two different low energy trans-lunar trajectories ultimately ending in lunar orbit. This paper describes the processes that resulted in successful orbit raise designs for both spacecraft.

  9. Driving Saturn's magnetospheric periodicities from the upper atmosphere/ionosphere

    Science.gov (United States)

    Jia, Xianzhe; Kivelson, Margaret G.; Gombosi, Tamas I.

    2012-04-01

    Saturn's magnetospheric structure and the intensity of radio frequency emissions from its immediate surroundings are modulated at close to the planet's rotation period. Analogous rotation-modulated variations at Jupiter are readily interpreted as effects of the non-axisymmetric intrinsic magnetic field. At Saturn, to the contrary, the high level of axial symmetry in the intrinsic field suggests that the periodicity is not internally imposed. A number of mechanisms have been proposed to account for the observations. Each model explains a subset of the observations in a qualitative manner, but no quantitative models yet exist. Here, using a magnetohydrodynamic simulation, we investigate the magnetospheric perturbations that arise from a localized vortical flow structure in the ionosphere near 70° S-latitude that rotates at roughly the rate of planetary rotation. The model reproduces nearly quantitatively a host of observed magnetospheric periodicities associated with the period of the dominant (southern) radio frequency emissions during the Cassini epoch including rotating, quasi-uniform magnetic perturbations in the equatorial plane, rotating mass density perturbations, periodic plasmoid releases that we associate with observed bursts of energetic neutral atoms (ENAs), periodic oscillations of magnetospheric boundaries, current sheet flapping, and periodic modulation of the field-aligned currents linked to Saturn's kilometric radiation (SKR). The model is not unique but is representative of a class of models in which asymmetric flows in the (as yet unmeasured) upper atmosphere couple to the ionosphere and generate currents that flow into the magnetosphere. It can be extended to include the second periodicity that has been associated with SKR emissions in the northern hemisphere.

  10. Artificial Neural Network L* from different magnetospheric field models

    Science.gov (United States)

    Yu, Y.; Koller, J.; Zaharia, S. G.; Jordanova, V. K.

    2011-12-01

    The third adiabatic invariant L* plays an important role in modeling and understanding the radiation belt dynamics. The popular way to numerically obtain the L* value follows the recipe described by Roederer [1970], which is, however, slow and computational expensive. This work focuses on a new technique, which can compute the L* value in microseconds without losing much accuracy: artificial neural networks. Since L* is related to the magnetic flux enclosed by a particle drift shell, global magnetic field information needed to trace the drift shell is required. A series of currently popular empirical magnetic field models are applied to create the L* data pool using 1 million data samples which are randomly selected within a solar cycle and within the global magnetosphere. The networks, trained from the above L* data pool, can thereby be used for fairly efficient L* calculation given input parameters valid within the trained temporal and spatial range. Besides the empirical magnetospheric models, a physics-based self-consistent inner magnetosphere model (RAM-SCB) developed at LANL is also utilized to calculate L* values and then to train the L* neural network. This model better predicts the magnetospheric configuration and therefore can significantly improve the L*. The above neural network L* technique will enable, for the first time, comprehensive solar-cycle long studies of radiation belt processes. However, neural networks trained from different magnetic field models can result in different L* values, which could cause mis-interpretation of radiation belt dynamics, such as where the source of the radiation belt charged particle is and which mechanism is dominant in accelerating the particles. Such a fact calls for attention to cautiously choose a magnetospheric field model for the L* calculation.

  11. Global problems in magnetospheric plasma physics and prospects for their solution

    Science.gov (United States)

    Roederer, J. G.

    1977-01-01

    Selected problems in magnetospheric plasma physics are critically reviewed. The discussion is restricted to questions that are 'global' in nature (i.e., involve the magnetosphere as a whole) and that are beyond the stage of systematic survey or isolated study requirements. Only low-energy particle aspects are discussed. The article focuses on the following subjects: (1) the effect of the interplanetary magnetic field on the topography, topology, and stability of the magnetospheric boundary; (2) solar-wind plasma entry into the magnetosphere; (3) plasma storage and release mechanisms in the magnetospheric tail; and (4) magnetic-field-aligned currents and magnetosphere-ionosphere interactions. A brief discussion of the prospects for the solution of these problems during and after the International Magnetospheric Study is given.

  12. The aurora and the magnetosphere - The Chapman Memorial Lecture. [dynamo theory development, 1600-present

    Science.gov (United States)

    Akasofu, S.-I.

    1974-01-01

    Review of recent progress in magnetospheric physics, in particular, in understanding the magnetospheric substorm. It is shown that a number of magnetospheric phenomena can now be understood by viewing the solar wind-magnetosphere interaction as an MHD dynamo; auroral phenomena are powered by the dynamo. Also, magnetospheric responses to variations of the north-south and east-west components of the interplanetary magnetic field have been identified. The magnetospheric substorm is entirely different from the responses of the magnetosphere to the southward component of the interplanetary magnetic field. It may be associated with the formation of a neutral line within the plasma sheet and with an enhanced reconnection along the line. A number of substorm-associated phenomena can be understood by noting that the new neutral line formation is caused by a short-circuiting of a part of the magnetotail current.

  13. Earth materials and earth dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, K; Shankland, T. [and others

    2000-11-01

    In the project ''Earth Materials and Earth Dynamics'' we linked fundamental and exploratory, experimental, theoretical, and computational research programs to shed light on the current and past states of the dynamic Earth. Our objective was to combine different geological, geochemical, geophysical, and materials science analyses with numerical techniques to illuminate active processes in the Earth. These processes include fluid-rock interactions that form and modify the lithosphere, non-linear wave attenuations in rocks that drive plate tectonics and perturb the earth's surface, dynamic recrystallization of olivine that deforms the upper mantle, development of texture in high-pressure olivine polymorphs that create anisotropic velocity regions in the convecting upper mantle and transition zone, and the intense chemical reactions between the mantle and core. We measured physical properties such as texture and nonlinear elasticity, equation of states at simultaneous pressures and temperatures, magnetic spins and bonding, chemical permeability, and thermal-chemical feedback to better characterize earth materials. We artificially generated seismic waves, numerically modeled fluid flow and transport in rock systems and modified polycrystal plasticity theory to interpret measured physical properties and integrate them into our understanding of the Earth. This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

  14. Effects of a solar wind dynamic pressure increase in the magnetosphere and in the ionosphere

    Directory of Open Access Journals (Sweden)

    L. Juusola

    2010-10-01

    Full Text Available On 17 July 2005, an earthward bound north-south oriented magnetic cloud and its sheath were observed by the ACE, SoHO, and Wind solar wind monitors. A steplike increase of the solar wind dynamic pressure during northward interplanetary magnetic field conditions was related to the leading edge of the sheath. A timing analysis between the three spacecraft revealed that this front was not aligned with the GSE y-axis, but had a normal (−0.58,0.82,0. Hence, the first contact with the magnetosphere occurred on the dawnside rather than at the subsolar point. Fortunately, Cluster, Double Star 1, and Geotail happened to be distributed close to the magnetopause in this region, which made it possible to closely monitor the motion of the magnetopause. After the pressure front had impacted the magnetosphere, the magnetopause was perceived first to move inward and then immediately to correct the overshoot by slightly expanding again such that it ended up between the Cluster constellation with Double Star 1 inside the magnetosphere and Geotail in the magnetosheath. Coinciding with the inward and subsequent outward motion, the ground-based magnetic field at low latitudes was observed to first strengthen and then weaken. As the magnetopause position stabilised, so did the ground-based magnetic field intensity, settling at a level slightly higher than before the pressure increase. Altogether the magnetopause was moving for about 15 min after its first contact with the front. The high latitude ionospheric signature consisted of two parts: a shorter (few minutes and less intense preliminary part comprised a decrease of AL and a negative variation of PC. A longer (about ten minutes and more intense main part of the signature comprised an increase of AU and a positive variation of PC. Measurements from several ground-based magnetometer networks (210 MM CPMN, CANMOS, CARISMA, GIMA, IMAGE, MACCS, SuperMAG, THEMIS, TGO were used to obtain information on the

  15. Radio Sounding Techniques for the Galilean Icy Moons and their Jovian Magnetospheric Environment

    Science.gov (United States)

    Green, James L.; Markus, Thursten; Fung, Shing F.; Benson, Robert F.; Reinich, Bodo W.; Song, Paul; Gogineni, S. Prasad; Cooper, John F.; Taylor, William W. L.; Garcia, Leonard

    2004-01-01

    Radio sounding of the Earth's topside ionosphere and magnetosphere is a proven technique from geospace missions such as the International Satellites for Ionospheric Studies (ISIS) and the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE). Application of this technique to Jupiter's icy moons and the surrounding Jovian magnetosphere will provide unique remote sensing observations of the plasma and magnetic field environments and the subsurface conductivities, of Europa, Ganymede, and Callisto. Spatial structures of ionospheric plasma above the surfaces of the moons vary in response to magnetic-field perturbations from (1) magnetospheric plasma flows, (2) ionospheric currents from ionization of sputtered surface material, and (3) induced electric currents in salty subsurface oceans and from the plasma flows and ionospheric currents themselves. Radio sounding from 3 kHz to 10 MHz can provide the global electron densities necessary for the extraction of the oceanic current signals and supplements in-situ plasma and magnetic field measurements. While radio sounding requires high transmitter power for subsurface sounding, little power is needed to probe the electron density and magnetic field intensity near the spacecraft. For subsurface sounding, reflections occur at changes in the dielectric index, e.g., at the interfaces between two different phases of water or between water and soil. Variations in sub-surface conductivity of the icy moons can be investigated by radio sounding in the frequency range from 10 MHz to 50 MHz, allowing the determination of the presence of density and solid-liquid phase boundaries associated with oceans and related structures in overlying ice crusts. The detection of subsurface oceans underneath the icy crusts of the Jovian moons is one of the primary objectives of the Jupiter Icy Moons Orbiter (JIMO) mission. Preliminary modeling results show that return signals are clearly distinguishable be&een an ice crust with a thickness of

  16. Stationary magnetospheric convection on November 24, 1981. 1. A case study of "pressure gradient/minimum-B" auroral arc generation

    Directory of Open Access Journals (Sweden)

    J. M. Bosqued

    Full Text Available We present two case studies in the night and evening sides of the auroral oval, based on plasma and field measurements made at low altitudes by the AUREOL-3 satellite, during a long period of stationary magnetospheric convection (SMC on November 24, 1981. The basic feature of both oval crossings was an evident double oval pattern, including (1 a weak arc-type structure at the equatorial edge of the oval/polar edge of the diffuse auroral band, collocated with an upward field-aligned current (FAC sheet of sim1.0 µA m-2, (2 an intermediate region of weaker precipitation within the oval, (3 a more intense auroral band at the polar oval boundary, and (4 polar diffuse auroral zone near the polar cap boundary. These measurements are compared with the published magnetospheric data during this SMC period, accumulated by Yahnin et al. and Sergeev et al., including a semi-empirical radial magnetic field profile BZ in the near-Earth neutral sheet, with a minimum at about 10-14 RE. Such a radial BZ profile appears to be very similar to that assumed in the "minimum- B/cross-tail line current" model by Galperin et al. (GVZ92 as the "root of the arc", or the arc generic region. This model considers a FAC generator mechanism by Grad-Vasyliunas-Boström-Tverskoy operating in the region of a narrow magnetic field minimum in the near-Earth neutral sheet, together with the concept of ion non-adiabatic scattering in the "wall region". The generated upward FAC branch of the double sheet current structure feeds the steady auroral arc/inverted-V at the equatorial border of the oval. When the semi-empirical BZ profile is introduced in the GVZ92 model, a good agreement is found between the modelled current and the measured characteristics of the FACs associated with the equatorial arc. Thus the main predictions of the GVZ92 model concerning the "minimum-B" region are consistent with these data, while some small-scale features are not reproduced. Implications of the GVZ92

  17. Solar wind-magnetosphere coupling and the distant magnetotail: ISEE-3 observations

    Energy Technology Data Exchange (ETDEWEB)

    Slavin, J.A.; Smith, E.J.; Sibeck, D.G.; Baker, D.N.; Zwickl, R.D.; Akasofu, S.I.; Lepping, R.P.

    1985-09-01

    ISEE-3 Geotail observations are used to investigate the relationship between the interplanetary magnetic field, substorm activity, and the distant magnetotail. Magnetic field and plasma observations are used to present evidence for the existence of a quasi-permanent, curved reconnection neutral line in the distant tail. The distance to the neutral line varies from absolute value of X = 120 to 140 R/sub e/ near the center of the tail to beyond absolute value of X = 200 R/sub e/ at the flanks. Downstream of the neutral line the plasma sheet magnetic field is shown to be negative and directly proportional to negative B/sub z/ in the solar wind as observed by IMP-8. V/sub x/ in the distant plasma sheet is also found to be proportional to IMF B/sub z/ with southward IMF producing the highest anti-solar flow velocities. A global dayside reconnection efficiency of 20 +- 5% is derived from the ISEE-3/IMP-8 magnetic field comparisons. Substorm activity, as measured by the AL index, produces enhanced negative B/sub z/ and tailward V/sub x/ in the distant plasma sheet in agreement with the basic predictions of the reconnection-based models of substorms. The rate of magnetic flux transfer out of the tail as a function of AL is found to be consistent with previous near-earth studies. Similarly, the mass and energy fluxes carried by plasma sheet flow down the tail are consistent with theoretical mass and energy budgets for an open magnetosphere. In summary, the ISEE-3 Geotail observations appear to provide good support for reconnection models of solar wind-magnetosphere coupling and substorm energy rates. 40 refs., 5 figs.

  18. Solar wind-magnetosphere coupling and the distant magnetotail - ISEE-3 observations

    Science.gov (United States)

    Slavin, J. A.; Smith, E. J.; Sibeck, D. G.; Baker, D. N.; Zwickl, R. D.; Akasofu, S.-I.; Lepping, R. P.

    1986-01-01

    ISEE-3 Geotail observations are used to investigate the relationship between the interplanetary magnetic field, substorm activity, and the distant magnetotail. Magnetic field and plasma observations are used to present evidence for the existence of a quasi-permanent, curved reconnection neutral line in the distant tail. The distance to the neutral line varies from absolute value of X = 120 to 140 R/sub e near the center of the tail to beyond absolute value of X = 200 R/sub e at the flanks. Downstream of the neutral line the plasma sheet magnetic field is shown to be negative and directly proportional to negative B/sub z in the solar wind as observed by IMP-8. V/sub x in the distant plasma sheet is also found to be proportional to IMF B/sub z with southward IMF producing the highest anti-solar flow velocities. A global dayside reconnection efficiency of 20 + or - 5 percent is derived from the ISEE-3/IMP-8 magnetic field comparisons. Substorm activity, as measured by the AL index, produces enhanced negative B/sub z and tailward V/sub x in the distant plasma sheet in agreement with the basic predictions of the reconnection-based models of substorms. The rate of magnetic flux transfer out of the tail as a function of AL is found to be consistent with previous near-earth studies. Similarly, the mass and energy fluxes carried by plasma sheet flow down the tail are consistent with theoretical mass and energy budgets for an open magnetosphere. In summary, the ISEE-3 Geotail observations appear to provide good support for reconnection models of solar wind-magnetosphere coupling and substorm energy rates.

  19. Solar wind-magnetosphere coupling and the distant magnetotail: ISEE-3 observations

    Science.gov (United States)

    Slavin, J. A.; Smith, E. J.; Sibeck, D. G.; Baker, D. N.; Zwickl, R. D.; Akasofu, S. I.; Lepping, R. P.

    1985-01-01

    ISEE-3 Geotail observations are used to investigate the relationship between the interplanetary magnetic field, substorm activity, and the distant magnetotail. Magnetic field and plasma observations are used to present evidence for the existence of a quasi-permanent, curved reconnection neutral line in the distant tail. The distance to the neutral line varies from absolute value of X = 120 to 140 R/sub e near the center of the tail to beyond absolute value of X = 200 R/sub e at the flanks. Downstream of the neutral line the plasma sheet magnetic field is shown to be negative and directly proportional to negative B/sub z in the solar wind as observed by IMP-8. V/sub x in the distant plasma sheet is also found to be proportional to IMF B/sub z with southward IMF producing the highest anti-solar flow velocities. A global dayside reconnection efficiency of 20 +- 5% is derived from the ISEE-3/IMP-8 magnetic field comparisons. Substorm activity, as measured by the AL index, produces enhanced negative B/sub z and tailward V/sub x in the distant plasma sheet in agreement with the basic predictions of the reconnection-based models of substorms. The rate of magnetic flux transfer out of the tail as a function of AL is found to be consistent with previous near-Earth studies. Similarly, the mass and energy fluxes carried by plasma sheet flow down the tail are consistent with theoretical mass and energy budgets for an open magnetosphere. In summary, the ISEE-3 Geotail observations appear to provide good support for reconnection models of solar wind-magnetosphere coupling and substorm energy rates.

  20. An empirical RBF model of the magnetosphere parameterized by interplanetary and ground-based drivers

    Science.gov (United States)

    Tsyganenko, N. A.; Andreeva, V. A.

    2016-11-01

    In our recent paper (Andreeva and Tsyganenko, 2016), a novel method was proposed to model the magnetosphere directly from spacecraft data, with no a priori knowledge nor ad hoc assumptions about the geometry of the magnetic field sources. The idea was to split the field into the toroidal and poloidal parts and then expand each part into a weighted sum of radial basis functions (RBF). In the present work we take the next step forward by having developed a full-fledged model of the near magnetosphere, based on a multiyear set of space magnetometer data (1995-2015) and driven by ground-based and interplanetary input parameters. The model consolidates the largest ever amount of data and has been found to provide the best ever merit parameters, in terms of both the overall RMS residual field and record-high correlation coefficients between the observed and model field components. By experimenting with different combinations of input parameters and their time-averaging intervals, we found the best so far results to be given by the ram pressure Pd, SYM-H, and N-index by Newell et al. (2007). In addition, the IMF By has also been included as a model driver, with a goal to more accurately represent the IMF penetration effects. The model faithfully reproduces both externally and internally induced variations in the global distribution of the geomagnetic field and electric currents. Stronger solar wind driving results in a deepening of the equatorial field depression and a dramatic increase of its dawn-dusk asymmetry. The Earth's dipole tilt causes a consistent deformation of the magnetotail current sheet and a significant north-south asymmetry of the polar cusp depressions on the dayside. Next steps to further develop the new approach are also discussed.

  1. Dynamics of the Solar Wind Electromagnetic Energy Transmission Into Magnetosphere during Large Geomagnetic Storms

    Science.gov (United States)

    Kuznetsova, Tamara; Laptukhov, Alexej; Petrov, Valery

    Causes of the geomagnetic activity (GA) in the report are divided into temporal changes of the solar wind parameters and the changes of the geomagnetic moment orientation relative directions of the solar wind electric and magnetic fields. Based on our previous study we concluded that a reconnection based on determining role of mutual orientation of the solar wind electric field and geomagnetic moment taking into account effects of the Earth's orbital and daily motions is the most effective compared with existing mechanisms. At present a reconnection as paradigma that has applications in broad fields of physics needs analysis of experimental facts to be developed. In terms of reconnection it is important not only mutual orientation of vectors describing physics of interaction region but and reconnection rate which depends from rate of energy flux to those regions where the reconnection is permitted. Applied to magnetosphere these regions first of all are dayside magnetopause and polar caps. Influence of rate of the energy flux to the lobe magnetopause (based on calculations of the Poyting electromagnetic flux component controlling the reconnection rate along the solar wind velocity Pv) on planetary GA (Dst, Kp indices) is investigated at different phases of geomagnetic storms. We study also the rate of energy flux to the polar caps during storms (based on calculations of the Poyting flux vector component along the geomagnetic moment Pm) and its influence on magnetic activity in the polar ionosphere: at the auroral zone (AU,AL indices). Results allow to evaluate contributions of high and low latitude sources of electromagnetic energy to the storm development and also to clear mechanism of the electromagnetic energy transmission from the solar wind to the magnetosphere. We evaluate too power of the solar wind electromagnetic energy during well-known large storms and compare result with power of the energy sources of other geophysical processes (atmosphere, ocean

  2. Some evidence of ground power enhancements at frequencies of global magnetospheric modes at low latitude

    Science.gov (United States)

    Francia, P.; Villante, U.

    1997-01-01

    A statistical analysis of the power spectra of the geomagnetic field components H and D for periods ranging between 3 min and 1 h was conducted at a low-latitude observatory (LÁquila, L=1.6) at the minimum and maximum of the solar cycle. For both components, during daytime intervals, we found evidence of power enhancements at frequencies predicted for global modes of the Earthś magnetosphere and occasionally observed at auroral latitudes in the F-region drift velocities (approximately at 1.3, 1.9, 2.6, and 3.4 mHz). Nighttime observations reveal a relative low frequency H enhancement associated with the bay occurrence together with a peak in the H/D power ratio which sharply emerges at 1.2 mHz in the premidnight sector. The strong similarity between solar minimum and maximum suggests that these modes can be considered permanent magnetospheric features. A separate analysis on a two-month interval shows that the observed spectral characteristics are amplified by conditions of high-velocity solar wind. Acknowledgements. The authors are grateful to Prof. D. J. Southwood (Imperial College, London), J. C. Samson (University of Alberta, Edmonton), L. J. Lanzerotti (AT&T Bell Laboratories), A. Wolfe (New York City Technical College) and to Dr. M. Vellante (University of LÁquila) for helpful discussions. They also thank Dr. A. Meloni (Istituto Nazionale di Geofisica, Roma) who made available geomagnetic field observations from LÁquila Geomagnetic Observatory. This research activity at LÁquila is supported by MURST (40% and 60% contracts) and by GIFCO/CNR. Topical Editor K.-H. Glaßmeier thanks C. Waters and S. Fujita for their help in evaluating this paper.-> Francia->

  3. Continuous magnetic reconnection at Earth's magnetopause.

    Science.gov (United States)

    Frey, H U; Phan, T D; Fuselier, S A; Mende, S B

    2003-12-04

    The most important process that allows solar-wind plasma to cross the magnetopause and enter Earth's magnetosphere is the merging between solar-wind and terrestrial magnetic fields of opposite sense-magnetic reconnection. It is at present not known whether reconnection can happen in a continuous fashion or whether it is always intermittent. Solar flares and magnetospheric substorms--two phenomena believed to be initiated by reconnection--are highly burst-like occurrences, raising the possibility that the reconnection process is intrinsically intermittent, storing and releasing magnetic energy in an explosive and uncontrolled manner. Here we show that reconnection at Earth's high-latitude magnetopause is driven directly by the solar wind, and can be continuous and even quasi-steady over an extended period of time. The dayside proton auroral spot in the ionosphere--the remote signature of high-latitude magnetopause reconnection--is present continuously for many hours. We infer that reconnection is not intrinsically intermittent; its steadiness depends on the way that the process is driven.

  4. The Source of Planetary Period Oscillations in Saturn's Magnetosphere

    Science.gov (United States)

    Khurana, Krishan K.; Mitchell, Jonathan L.; Mueller, Ingo C. F.

    2017-04-01

    In this presentation, we resolve a three-decades old mystery of how Saturn is able to modulate its kilometric wave radiation and many field and plasma parameters at the planetary rotation period even though its magnetic field is extremely axisymmetric. Such waves emanating from the auroral regions of planets lacking solid surfaces have been used as clocks to measure the lengths of their days, because asymmetric internal magnetic fields spin-modulate wave amplitudes. A review by Carbary and Mitchell (2013, Periodicities in Saturn's magnetosphere, Reviews of Geophysics, 51, 1-30) on the topic summarized findings from over 200 research articles, on what the phenomena is, how it is manifested in a host of magnetospheric and auroral parameters; examined several proposed models and pointed out their shortcomings. The topic has now been explored in several topical international workshops, but the problem has remained unsolved so far. By quantitatively modeling the amplitudes and phases of these oscillations in the magnetic field observed by the Cassini spacecraft, we have now uncovered the generation mechanism responsible for these oscillations. We show that the observed oscillations are the manifestations of two global convectional conveyor belts excited in Saturn's upper atmosphere by auroral heating below its northern and southern auroral belts. We demonstrate that a feedback process develops in Saturn system such that the magnetosphere expends energy to drive convection in Saturn's upper stratosphere but gains back an amplified share in the form of angular momentum that it uses to enforce corotation in the magnetosphere and power its aurorae and radio waves. In essence, we have uncovered a new mechanism (convection assisted loss of angular momentum in an atmosphere) by which gaseous planets lose their angular momentum to their magnetospheres and outflowing plasma at rates far above previous predictions. We next show how the m = 1 convection system in the upper

  5. Snowball Earth

    OpenAIRE

    2016-01-01

    In the ongoing quest to better understand where life may exist elsewhere in the Universe, important lessons may be gained from our own planet. In particular, much can be learned from planetary glaciation events that Earth suffered ∼600 million years ago, so-called `Snowball Earth' episodes. I begin with an overview of how the climate works. This helps to explain how the ice-albedo feedback effect can destabilise a planet's climate. The process relies on lower temperatures causing more ice to ...

  6. Background electromagnetic noise characterization: the role of external and internal Earth sources

    Directory of Open Access Journals (Sweden)

    Antonio Meloni

    2015-07-01

    Full Text Available The Earth is surrounded by the ionosphere and magnetosphere that can roughly be seen schematically as two concentric shells. These two composed and inhomogeneous structured shells around the Earth selectively affect electromagnetic (EM waves propagation. Both ionosphere and magnetosphere interact also with particles and waves coming from external sources, generating electromagnetic phenomena that in turn might become sources of EM waves. Conversely, EM waves generated inside the ionosphere remain confined at various altitudes in this region, up to a so-called critical frequency limit, depending on frequency, EM waves can escape out of the ionosphere and magnetosphere or get through. The EM waves generated inside the magnetospheric cavity mainly originate as a result of the electrical activity in the atmosphere. It is well known that also man-made sources, now widely spread on Earth, are a fundamental source of EM waves; however, excluding certain frequencies employed in power distribution and communication, man-made noise can be dominant only at local scale, near their source. According to recent studies, EM waves are also generated in the Earth’s lithosphere; these waves were sometimes associated with earthquake activity showing, on the Earth’s surface, intensities that are generally orders of magnitude below the background EM noise. In this review paper, we illustrate EM waves of natural origin and discuss their characterization in order to try discriminate those of lithospheric origin detectable at or near the Earth’s surface.

  7. Mercury's Atmosphere and Magnetosphere: MESSENGER Third Flyby Observations

    Science.gov (United States)

    Slavin, James A.; Anderson, Brian J.; Baker, Daniel N.; Benna, Mehdi; Johnson, Catherine L.; Gloeckler, George; Killen, Rosemary M.; Krimigis, Stamatios M.; McClintock, William; McNutt, Ralph L., Jr.; Schriver, David; Solomon, Sean C.; Sprague, Ann L.; Vevack, Ronald J., Jr.; Zurbuchen, Thomas H.

    2009-01-01

    MESSENGER's third flyby of Mercury en route to orbit insertion about the innermost planet took place on 29 September 2009. The earlier 14 January and 6 October 2008 encounters revealed that Mercury's magnetic field is highly dipolar and stable over the 35 years since its discovery by Mariner 10; that a structured, temporally variable exosphere extends to great altitudes on the dayside and forms a long tail in the anti-sunward direction; a cloud of planetary ions encompasses the magnetosphere from the dayside bow shock to the downstream magnetosheath and magnetotail; and that the magnetosphere undergoes extremely intense magnetic reconnect ion in response to variations in the interplanetary magnetic field. Here we report on new results derived from observations from MESSENGER's Mercury Atmospheric and Surface Composition Spectrometer (MASCS), Magnetometer (MAG), and Energetic Particle and Plasma Spectrometer (EPPS) taken during the third flyby.

  8. Generation of auroral turbulence through the magnetosphere-ionosphere coupling

    Science.gov (United States)

    Watanabe, Tomo-Hiko; Kurata, Hiroaki; Maeyama, Shinya

    2016-12-01

    The shear Alfvén waves coupled with the ionospheric density fluctuations in auroral regions of a planetary magnetosphere are modeled by a set of the reduced magnetohydrodynamic and two-fluid equations. When the drift velocity of the magnetized plasma due to the background electric field exceeds a critical value, the magnetosphere-ionosphere (M-I) coupling system is unstable to the feedback instability which leads to formation of auroral arc structures with ionospheric density and current enhancements. As the feedback (primary) instability grows, a secondary mode appears and deforms the auroral structures. A perturbative (quasilinear) analysis clarifies the secondary growth of the Kelvin-Helmholtz type instability driven by the primary instability growth in the feedback M-I coupling. In the nonlinear stage of the feedback instability, furthermore, auroral turbulence is spontaneously generated, where the equipartition of kinetic and magnetic energy is confirmed in the quasi-steady turbulence.

  9. Simulations of the magnetospheres of accreting millisecond pulsars

    CERN Document Server

    Parfrey, Kyle; Beloborodov, Andrei M

    2016-01-01

    Accreting pulsars power relativistic jets, and display a complex spin phenomenology. These behaviours may be closely related to the large-scale configuration of the star's magnetic field. The total torque experienced by the pulsar comprises spin-up and spin-down contributions from different bundles of magnetic field lines; the spin-down `braking' torque is applied both by closed stellar field lines which enter the disc beyond the corotation radius, and those which are open and not loaded with disc material. The rates of energy and angular momentum extraction on these open field lines have lower bounds in the relativistic, magnetically dominated limit, due to the effective inertia of the electromagnetic field itself. Here we present the first relativistic simulations of the interaction of a pulsar magnetosphere with an accretion flow. Our axisymmetric simulations, with the pseudospectral PHAEDRA code, treat the magnetospheric, or coronal, regions using a resistive extension of force-free electrodynamics. The m...

  10. Lyapunov exponent of magnetospheric activity from AL time series

    Science.gov (United States)

    Vassiliadis, D.; Sharma, A. S.; Papadopoulos, K.

    1991-01-01

    A correlation dimension analysis of the AE index indicates that the magnetosphere behaves as a low-dimensional chaotic system with a dimension close to 4. Similar techniques are used to determine if the system's behavior is due to an intrinsic sensitivity to initial conditions and thus is truly chaotic. The quantity used to measure the sensitivity to initial conditions is the Liapunov exponent. Its calculation for AL shows that it is nonzero (0.11 + or - 0.05/min). This gives the exponential rate at which initially similar configurations of the magnetosphere evolve into completely different states. Also, predictions of deterministic nonlinear models are expected to deviate from the observed behavior at the same rate.

  11. An oblique pulsar magnetosphere with a plasma conductivity

    CERN Document Server

    Cao, Gang; Sun, Sineng

    2016-01-01

    An oblique pulsar magnetosphere with a plasma conductivity is studied by using a pseudo-spectral method. In the pseudo-spectral method, the time-dependent Maxwell equations are solved, both electric and magnetic fields are expanded in terms of the vector spherical harmonic (VSH) functions in spherical geometry and the divergencelessness of magnetic field is analytically enforced by a projection method. The pulsar magnetospheres in infinite (i. e., force-free approximation) and finite conductivities are simulated and a family of solutions that smoothly transition from the Deutsch vacuum solution to the force-free solution are obtained. The $\\sin^2\\alpha$ dependence of the spin-down luminosity on the magnetic inclination angle $\\alpha$ in which the full electric current density are taken into account is retrieved in the force-free regime.

  12. AB INITIO PULSAR MAGNETOSPHERE: THE ROLE OF GENERAL RELATIVITY

    Energy Technology Data Exchange (ETDEWEB)

    Philippov, Alexander A.; Cerutti, Benoit; Spitkovsky, Anatoly [Department of Astrophysical Sciences, Princeton University, Ivy Lane, Princeton, NJ 08544 (United States); Tchekhovskoy, Alexander, E-mail: sashaph@princeton.edu [Departments of Physics and Astronomy, University of California, Berkeley, CA 94720 (United States)

    2015-12-20

    It has recently been demonstrated that self-consistent particle-in-cell simulations of low-obliquity pulsar magnetospheres in flat spacetime show weak particle acceleration and no pair production near the poles. We investigate the validity of this conclusion in a more realistic spacetime geometry via general-relativistic particle-in-cell simulations of the aligned pulsar magnetosphere with pair formation. We find that the addition of the frame-dragging effect makes the local current density along the magnetic field larger than the Goldreich–Julian value, which leads to unscreened parallel electric fields and the ignition of a pair cascade. When pair production is active, we observe field oscillations in the open field bundle, which could be related to pulsar radio emission. We conclude that general-relativistic effects are essential for the existence of the pulsar mechanism in low-obliquity rotators.

  13. Lyapunov exponent of magnetospheric activity from AL time series

    Science.gov (United States)

    Vassiliadis, D.; Sharma, A. S.; Papadopoulos, K.

    1991-01-01

    A correlation dimension analysis of the AE index indicates that the magnetosphere behaves as a low-dimensional chaotic system with a dimension close to 4. Similar techniques are used to determine if the system's behavior is due to an intrinsic sensitivity to initial conditions and thus is truly chaotic. The quantity used to measure the sensitivity to initial conditions is the Liapunov exponent. Its calculation for AL shows that it is nonzero (0.11 + or - 0.05/min). This gives the exponential rate at which initially similar configurations of the magnetosphere evolve into completely different states. Also, predictions of deterministic nonlinear models are expected to deviate from the observed behavior at the same rate.

  14. Digital Earth - A sustainable Earth

    Science.gov (United States)

    Mahavir

    2014-02-01

    All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.

  15. A joint Cluster and ground-based instruments study of two magnetospheric substorm events on 1 September 2002

    Directory of Open Access Journals (Sweden)

    N. C. Draper

    2004-12-01

    Full Text Available We present a coordinated ground- and space-based multi-instrument study of two magnetospheric substorm events that occurred on 1 September 2002, during the interval from 18:00 UT to 24:00 UT. Data from the Cluster and Polar spacecraft are considered in combination with ground-based magnetometer and HF radar data. During the first substorm event the Cluster spacecraft, which were in the Northern Hemisphere lobe, are to the west of the main region affected by the expansion phase. Nevertheless, substorm signatures are seen by Cluster at 18:25 UT (just after the expansion phase onset as seen on the ground at 18:23 UT, despite the ~5 RE} distance of the spacecraft from the plasma sheet. The Cluster spacecraft then encounter an earthward-moving diamagnetic cavity at 19:10 UT, having just entered the plasma sheet boundary layer. The second substorm expansion phase is preceded by pseudobreakups at 22:40 and 22:56 UT, at which time thinning of the near-Earth, L=6.6, plasma sheet occurs. The expansion phase onset at 23:05 UT is seen simultaneously in the ground magnetic field, in the magnetotail and at Polar's near-Earth position. The response in the ionospheric flows occurs one minute later. The second substorm better fits the near-Earth neutral line model for substorm onset than the cross-field current instability model.

    Key words. Magnetospheric physics (Magnetosphereionosphere interactions; Magnetic reconnection; Auroral phenomenon

  16. Importance of post-shock streams and sheath region as drivers of intense magnetospheric storms and high-latitude activity

    Directory of Open Access Journals (Sweden)

    K. E. J. Huttunen

    2004-04-01

    Full Text Available Magnetic disturbances in the Earth's magnetosphere can be very different depending on the type of solar wind driver. We have determined the solar wind causes for intense magnetic storms (Dst<-100nT over a 6-year period from the beginning of 1997 to the end of 2002, using observations by the WIND and ACE spacecraft. We have taken into consideration whether the storm was caused by the sheath region or by the following interplanetary coronal mass ejection (ICME. We also divided ICMEs into those having a magnetic cloud structure and those without such a structure. We found that post-shock streams and sheath regions caused the largest fraction of intense magnetic storms. We present four periods of magnetospheric activity in more detail. One of the events was caused by a magnetic cloud (10-11 August 2000 and the rest (13-14 July 2000, 8-9 June 2000 and 17-18 April 2001 by sheath regions and post-shock streams. We have used several magnetic indices to monitor the low- and high-latitude magnetospheric response to these different solar wind structures. Two of the events are interesting examples where at first strong high-latitude activity took place and the low-latitude response followed several hours later. These events demonstrate that low- and high-latitude activity do not always occur concurrently and the level of activity may be very different. According to the examples shown the evolution of the pressure-corrected Dst index was more difficult to model for a sheath region or a post-shock stream driven storm than for a storm caused by a magnetic cloud.

  17. ULF wave penetration in the inner magnetosphere related to radiation belt electron acceleration and losses: Observations and model simulations

    Science.gov (United States)

    Georgiou, Marina; Daglis, Ioannis; Zesta, Eftyhia; Sibeck, David; Fok, Mei-ching; Balasis, Georgios; Mann, Ian; Tsinganos, Kanaris

    2017-04-01

    Periodic oscillations in the Earth's magnetic field with frequencies in the range of a few mHz (ULF waves) can influence radiation belt dynamics due to their potential for strong interactions with charged particles and in particular, relativistic electrons. We have explored possible relationships between the spatial and temporal profile of ULF wave power with relativistic electron fluxes as well as different solar wind parameters. We used data from multiple ground magnetometer arrays contributing to the worldwide SuperMAG collaboration to calculate the ULF wave power in the Pc5 frequency band (2 - 7 mHz) from for a total of 40 moderate and intense magnetic storms over the last solar cycle 23. During the main phase of both sets of storms, there is a marked penetration of Pc5 wave power to L-shells as low as 2-3. The penetration of ULF waves is deeper into the inner magnetosphere during intense magnetic storms characterised by enhanced post-storm electron fluxes. Furthermore, later in the recovery phase, enhanced Pc5 wave activity was found to persist longer for storms marked by electron-enhanced storms flux enhancement than for those that do not produce such electron flux enhancements. Growth and decay characteristics of Pc5 waves were explored in association with the plasmapause location, determined from IMAGE EUV observations. Pc5 wave power enhancements and relativistic electron acceleration were not only intimately linked, but also restricted beyond the plasmapause. These observations provided the basis for a superposed epoch analysis, the results of which are compared to predictions from the Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model. These simulations are critical for understanding the extent to which ULF wave electric fields are responsible for the observed electron acceleration and for examining the nature of mechanisms responsible for driving such large-amplitude ULF waves in the magnetosphere. This work has been supported by the NOA

  18. Symmetric or asymmetric energy transfer from Interplanetary Coronal Mass Ejections to the magnetosphere depending on the solar dipole

    Science.gov (United States)

    Baranyi, T.; Ludmány, A.

    The annual behaviour of monthly number of hours spent by the Earth in domains of either positive or negative By component of the interplanetary magnetic field (IMF) was studied. We used the hourly OMNI data in the cases of Kp > 3. The study was confined to the ascending phases of the four recent sunspot cycles when Interplanetary Coronal Mass Ejections (ICMEs) dominate among the sources of geoeffectiveness. Definite differences were found between the annual variations of the hourly sums. When the solar dipole is opposite to the terrestrial one, the sums exhibit the the combined effect of Rosenberg-Coleman and Russell-McPherron effects. Thus, in the geomagnetically active hours the negative By dominates during the first half of the year and the positive By dominates during the second half of the year. However, these effects can not be detected in the occurrence of the negative and positive GSM By values when the solar and terrestrial dipoles are parallel. In this case one can see polarity-independent semiannual variations instead of the polarity-dependent opposite annual variations. It is well-known that the By component modulates the energy transfer from the solar wind to the magnetosphere causing marked asymmetries in magnetospheric convective flow patterns at high latitudes. Our results hint that the occurrences of these asymmetries related to the ICMEs depend on the solar dipole cycle. In the antiparallel years one of them dominates during half a year causing asymmetric energy transfer to the magnetosphere. In the parallel years the occurrences of the two kind of asymmetries are equal on monthly time scale, thus the energy transfer is symmetric within a monthly and yearly time interval.

  19. The Unreasonable Success of Magnetosphere-Ionosphere Coupling Theory

    Science.gov (United States)

    Vasyliūnas, V. M.

    2002-12-01

    The description of plasma dynamics on the basis of self-consistent coupling between magnetosphere and ionosphere, as first systematized in the early 1970's, is arguably one of the most successful theories in magnetospheric physics. It accounts for the pattern of magnetospheric convection at auroral and low latitudes, the distribution of Birkeland currents, and the dependence on changing orientation of the interplanetary magnetic field. It can incorporate assumed effects, e.g. of particle sources or conductance variations, to almost any degree of complexity at moderate cost in additional computing effort (compare the levels of physics included in advanced versions of the Rice Convection Model and of global MHD simulations, respectively). Such success combined with relative simplicity, however, is possible only because the theory has limited itself in significant ways. It treats the system in effect as doubly two-dimensional: height-integrated ionosphere plus field-line-integrated magnetosphere, with the background magnetic field structure treated as known or derived from some empirical model. It assumes that the system is always in slowly evolving quasi-equilibrium and deals only with time scales long compared to wave propagation times. Hence the theory is not easily applied where genuine 3D aspects (e.g. height and field-line dependence), poorly known or variable magnetic fields (e.g. open field lines), or transient responses e.g. to rapid solar-wind changes are important, and it is intrinsically incapable of describing explosive non-equilibrium developments such as substorm onset. Possible extensions of the theory, comparison with numerical-simulation approaches, and implications for general space plasma physics (E-J vs. B-V) will be discussed.

  20. Non-linear high-frequency waves in the magnetosphere

    Indian Academy of Sciences (India)

    S Moolla; R Bharuthram; S V Singh; G S Lakhina

    2003-12-01

    Using fluid theory, a set of equations is derived for non-linear high-frequency waves propagating oblique to an external magnetic field in a three-component plasma consisting of hot electrons, cold electrons and cold ions. For parameters typical of the Earth’s magnetosphere, numerical solutions of the governing equations yield sinusoidal, sawtooth or bipolar wave-forms for the electric field.

  1. Shear driven waves in the induced magnetosphere of Mars

    Energy Technology Data Exchange (ETDEWEB)

    Gunell, H; Koepke, M [Department of Physics, West Virginia University, Morgantown, WV 26506-6315 (United States); Amerstorfer, U V; Biernat, H K [Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, A-8042 Graz (Austria); Nilsson, H; Holmstroem, M; Lundin, R; Barabash, S [Swedish Institute of Space Physics, P.O. Box 812, SE-981 28 Kiruna (Sweden); Grima, C [Laboratoire de Planetologie de Grenoble, BP-53, F-38041 Grenoble Cedex 9 (France); Fraenz, M [Max-Planck-Institut fuer Sonnensystemforschung, Max-Planck-Strasse 2, 37191 Katlenburg-Lindau (Germany); Winningham, J D; Frahm, R A [Southwest Research Institute, San Antonio, TX 7228-0510 (United States); Sauvaud, J-A; Fedorov, A [Centre d' Etude Spatiale des Rayonnements, BP-4346, F-31028 Toulouse (France); Erkaev, N V [Institute of Computational Modelling, Russian Academy of Sciences, 660036 Krasnoyarsk-36 (Russian Federation)], E-mail: herbert.gunell@physics.org

    2008-07-15

    We present measurements of oscillations in the electron density, ion density and ion velocity in the induced magnetosphere of Mars. The fundamental frequency of the oscillations is a few millihertz, but higher harmonics are present in the spectrum. The oscillations are observed in a region where there is a velocity shear in the plasma flow. The fundamental frequency is in agreement with computational results from an ideal-MHD model. An interpretation based on velocity-shear instabilities is described.

  2. Excitation of field line resonances by sources outside the magnetosphere

    Directory of Open Access Journals (Sweden)

    A. D. M. Walker

    2005-11-01

    Full Text Available Field line resonances are thought to be excited by sources either at the magnetopause or outside it. Recent observations suggest that they may be associated with coherent oscillations or pressure pulses in the solar wind. In either case the excitation mechanism can be understood by considering the incidence of a harmonic wave on the magnetopause from outside the magnetosphere. Calculations are performed in a plane stratified model that consists of (i a magnetosheath region streaming tailward at uniform velocity (ii a sharp boundary representing the magnetopause, (iii a magnetosphere region in which the Alfvén speed increases monotonically with distance from the magnetopause. The structure implies the existence of a propagating region within the magnetopause bounded by a reflection level or turning point. Beyond this is a region in which waves are evanescent and a resonance level. The reflection and transmission of harmonic waves incident from the magnetosheath is considered in this model. It is shown that, in most cases, because of the mismatch between the magnetosphere and the magnetopause, the wave is reflected from the magnetopause with little penetration. At critical frequencies corresponding to the natural frequencies of the cavity formed between the magnetopause and turning point the signal excites the cavity and may leak evanescently to the resonance. The calculation includes the effect of the counter-streaming magnetosheath and magnetosphere plasmas on the wave. This can lead to amplification or attenuation. The nature of the processes that lead to transmission of the wave from magnetosheath to resonance are considered by synthesising the signal from plane wave spectra. A number of mechanisms for exciting cavity modes are reviewed and the relationship of the calculations to these mechanisms are discussed. Observations needed to discriminate between the mechanisms are specified.

  3. The force-free twisted magnetosphere of a neutron star

    Science.gov (United States)

    Akgün, T.; Miralles, J. A.; Pons, J. A.; Cerdá-Durán, P.

    2016-10-01

    We present a detailed analysis of the properties of twisted, force-free magnetospheres of non-rotating neutron stars, which are of interest in the modelling of magnetar properties and evolution. In our models the magnetic field smoothly matches to a current-free (vacuum) solution at some large external radius, and they are specifically built to avoid pathological surface currents at any of the interfaces. By exploring a large range of parameters, we find a few remarkable general trends. We find that the total dipolar moment can be increased by up to 40 per cent with respect to a vacuum model with the same surface magnetic field, due to the contribution of magnetospheric currents to the global magnetic field. Thus, estimates of the surface magnetic field based on the large-scale dipolar braking torque are slightly overestimating the surface value by the same amount. Consistently, there is a moderate increase in the total energy of the model with respect to the vacuum solution of up to 25 per cent, which would be the available energy budget in the event of a fast, global magnetospheric reorganization commonly associated with magnetar flares. We have also found the interesting result of the existence of a critical twist (ϕmax ≲ 1.5 rad), beyond which we cannot find any more numerical solutions. Combining the models considered in this paper with the evolution of the interior of neutron stars will allow us to study the influence of the magnetosphere on the long-term magnetic, thermal, and rotational evolution.

  4. Stormtime Magnetosphere-Ionosphere-Thermosphere Interactions and Dynamics

    Science.gov (United States)

    2013-03-13

    SIGNATURE PAGE Using Government drawings, specifications, or other data included in this document for any purpose other than Government...findings. REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this collection of information is estimated to...distribution is unlimited. 8 LANL /NASA sponsored Theory of the Magnetosphere Workshop in Santa Fe and in a University of Oslo, Department of Physics

  5. Ionosphere-magnetosphere studies using ground based VLF radio propagation technique: an Indian example

    Science.gov (United States)

    Chakravarty, Subhas

    Since IGY period (1957-58), natural and artificially produced Very Low Frequency (VLF) elec-tromagnetic radiations are being recorded at large number of ground stations all over the world and on-board satellites to study various radio wave-thermal/energetic plasma interactive pro-cesses related to earth's ionosphere-plasmasphere-magnetosphere environment. The terrestrial propagation of these VLF radio waves are primarily enabled through the earth ionosphere wave guide (EIWG) mode to long horizontal distances around the globe and ducted along the ge-omagnetic field lines into the conjugate hemisphere through the plasmasphere-magnetosphere regions. The time frequency spectra of the received signals indicate presence of dispersion (wave/group velocities changing with frequency) and various cut-off frequencies based on the width of the EIWG, electron gyro and plasma frequencies etc., providing several types of received signals like whistlers, chorus, tweeks, hiss and hisslers which can be heard on loud-speakers/earphones with distinguishing audio structures. While the VLF technique has been a very effective tool for studying middle and high latitude phenomena, the importance of the similar and anomalous observations over the Indian low latitude stations provide potentially new challenges for their scientific interpretation and modelling. The ducted and non-ducted magnetospheric propagation, pro-longitudinal (PL) mode, low latitude TRIMPI/TLE (Tran-sient Luminous Emissions) or other effects of wave-particle/wave-wave interactions, effects due to ionospheric irregularities and electric fields, full wave solutions to D-region ionisation per-turbations due to solar and stellar energetic X-and γ ray emissions during normal and flaring conditions are a few problems which have been addressed in these low latitude studies over India. Since the conjugate points of Indian stations lie over the Indian oceanic region, the VLF propagation effects would be relatively free from

  6. Cluster recent highlights in magnetospheric physics

    Science.gov (United States)

    Escoubet, C. Philippe; Laakso, Harri; Goldstein, Mevlyn; Masson, Arnaud

    2016-07-01

    After more than 15 years in space, the Cluster mission is continuing to deliver groundbreaking results, thanks to its ability to move the four spacecraft with respect to each other, according to the science topic to be studied. The main goal of the Cluster mission, made of four identical spacecraft carrying each 11 complementary instruments, is to study in three dimensions the key plasma processes at work in the main regions of the Earth's environment: solar wind and bow shock, magnetopause, polar cusps, magnetotail, and auroral zone. During the course of the mission, the relative distance between the four spacecraft has been varied more than 55 times from a few km up to 36000 km to address the various scientific objectives. The smallest distance achieved between two Cluster spacecraft was 3.1 km in December 2015, about 50 times smaller than planned at the beginning of the mission. The rate of change of separation distances has accelerated in the last few years with the Guest Investigator programme that allowed scientists in the community to propose special science programmes requiring a new spacecraft constellation. We will present recent science highlights obtained such as solar wind reconnection and bifurcated current sheet development, multi-altitude measurements of field aligned currents, reconnection efficiency in accelerating particles and effect of cold ions, motion of X-lines, speed and direction of tail reconnection events, flux transfer events evolution, new method to find magnetic nulls outside the Cluster tetrahedron, interplanetary shock waves very quick damping and origin of theta auroras. We will also present the distribution of data through the Cluster Science Data System (CSDS), and the Cluster Science Archive (CSA). CSA was implemented to provide, for the first time for a plasma physics mission, a permanent and public archive of all the high-resolution data from all instruments.

  7. The Near-Earth Plasma Environment

    Science.gov (United States)

    Pfaff, Robert F., Jr.

    2012-01-01

    An overview of the plasma environment near the earth is provided. We describe how the near-earth plasma is formed, including photo-ionization from solar photons and impact ionization at high latitudes from energetic particles. We review the fundamental characteristics of the earth's plasma environment, with emphasis on the ionosphere and its interactions with the extended neutral atmosphere. Important processes that control ionospheric physics at low, middle, and high latitudes are discussed. The general dynamics and morphology of the ionized gas at mid- and low-latitudes are described including electrodynamic contributions from wind-driven dynamos, tides, and planetary-scale waves. The unique properties of the near-earth plasma and its associated currents at high latitudes are shown to depend on precipitating auroral charged particles and strong electric fields which map earthward from the magnetosphere. The upper atmosphere is shown to have profound effects on the transfer of energy and momentum between the high-latitude plasma and the neutral constituents. The article concludes with a discussion of how the near-earth plasma responds to magnetic storms associated with solar disturbances.

  8. Particle Signatures Observed by Geotail at 9-30 Re and Mapping of Auroral Regions to the Magnetosphere Without Field-Line Models

    Science.gov (United States)

    Shirai, H.; Hori, T.; Mukai, T.

    2004-12-01

    The Geotail spacecraft has often observed a rapid change of particle signatures at a geocentric distance around 10-15 Re. As the spacecraft approached the near-Earth region, particle spectra showing a low temperature, a small particle flux, and a large fluctuation in the magnetotail changed to those with a high temperature, a large flux, and a small fluctuation in the near-Earth region. This change often occurred rapidly as if there was a sharp boundary between the tail plasma sheet and the near-Earth plasma sheet. In the present paper, we call this boundary "near-Earth PS boundary (NEPS boundary)." As pointed out by recent studies, the region between the tail plasma sheet and the near-Earth plasma sheet may be a key to solving problems on dynamics of the magnetosphere [Shiokawa et al., 1998] and to studying chaotic behavior of magnetospheric particles [Zelenyi et al., 2000, 2002]. In this paper, we investigate the position of the NEPS boundary in detail and present a map showing its occurrence on the equatorial plane. We also examine characteristics of the NEPS boundary and indicate that they are very similar to characteristics of the equatorward boundary of the so-called "Wall Region" [Ashour-Abdalla et al, 1992] or "Ion Gap" [Bosqued et al, 1993; Delcourt et al., 1996], which has been observed at low altitudes. We compare the NEPS boundary with the equatorward boundary of the Wall Region (Ion Gap) identified by the low-altitude satellite Akebono. It is concluded that the boundary of the Wall Region (Ion Gap) is the field-aligned projection of the NEPS boundary detected by Geotail in the magnetosphere. This conclusion enables us to map the key region (10-15 Re) to the auroral altitudes. The result of the mapping demonstrates that the key region is projected on the latitudes of 65-70 degrees at auroral altitudes. Finally, we discuss a new method to map auroral regions to the magnetosphere without using field line models but using observed boundaries. It is

  9. Analysis of plasma waves observed in the inner Saturn magnetosphere

    Directory of Open Access Journals (Sweden)

    J. D. Menietti

    2008-09-01

    Full Text Available Plasma waves observed in the Saturn magnetosphere provide an indication of the plasma population present in the rotationally dominated inner magnetosphere. Electrostatic cyclotron emissions often with harmonics and whistler mode emission are a common feature of Saturn's inner magnetosphere. The electron observations for a region near 5 RS outside and near a plasma injection region indicate a cooler low-energy (<100 eV, nearly isotropic plasma, and a much warmer (E>1000 eV more pancake or butterfly distribution. We model the electron plasma distributions to conduct a linear dispersion analysis of the wave modes. The results suggest that the electrostatic electron cyclotron emissions can be generated by phase space density gradients associated with a loss cone that may be up to 20° wide. This loss cone is sometimes, but not always, observed because the field of view of the electron detectors does not include the magnetic field line at the time of the observations. The whistler mode emission can be generated by the pancake-like distribution and temperature anisotropy (T/T||>1 of the warmer plasma population.

  10. A novel look at the pulsar force-free magnetosphere

    CERN Document Server

    Petrova, S A

    2016-01-01

    The stationary axisymmetric force-free magnetosphere of a pulsar is considered. We present an exact dipolar solution of the pulsar equation, construct the magnetospheric model on its basis and examine its observational support. The new model has toroidal rather than common cylindrical geometry, in line with that of the plasma outflow observed directly as the pulsar wind nebula at much larger spatial scale. In its new configuration, the axisymmetric magnetosphere consumes the neutron star rotational energy much more efficiently, implying re-estimation of the stellar magnetic field, $B_{\\mathrm new}^0=3.3\\times 10^{-4}B/P$, where $P$ is the pulsar period. Then the 7-order scatter of the magnetic field derived from the rotational characteristics of the pulsars observed appears consistent with the $\\cot\\chi$-law, where $\\chi$ is a random quantity uniformly distributed in the interval $[0,\\pi/2]$. Our result is suggestive of a unique actual magnetic field strength of the neutron stars along with a random angle bet...

  11. Modeling the Inner Magnetosphere: Radiation Belts, Ring Current, and Composition

    Science.gov (United States)

    Glocer, Alex

    2011-01-01

    The space environment is a complex system defined by regions of differing length scales, characteristic energies, and physical processes. It is often difficult, or impossible, to treat all aspects of the space environment relative to a particular problem with a single model. In our studies, we utilize several models working in tandem to examine this highly interconnected system. The methodology and results will be presented for three focused topics: 1) Rapid radiation belt electron enhancements, 2) Ring current study of Energetic Neutral Atoms (ENAs), Dst, and plasma composition, and 3) Examination of the outflow of ionospheric ions. In the first study, we use a coupled MHD magnetosphere - kinetic radiation belt model to explain recent Akebono/RDM observations of greater than 2.5 MeV radiation belt electron enhancements occurring on timescales of less than a few hours. In the second study, we present initial results of a ring current study using a newly coupled kinetic ring current model with an MHD magnetosphere model. Results of a dst study for four geomagnetic events are shown. Moreover, direct comparison with TWINS ENA images are used to infer the role that composition plays in the ring current. In the final study, we directly model the transport of plasma from the ionosphere to the magnetosphere. We especially focus on the role of photoelectrons and and wave-particle interactions. The modeling methodology for each of these studies will be detailed along with the results.

  12. Three-dimensional magnetospheric equilibrium with isotropic pressure

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, C.Z.

    1995-05-01

    In the absence of the toroidal flux, two coupled quasi two-dimensional elliptic equilibrium equations have been derived to describe self-consistent three-dimensional static magnetospheric equilibria with isotropic pressure in an optimal ({Psi},{alpha},{chi}) flux coordinate system, where {Psi} is the magnetic flux function, {chi} is a generalized poloidal angle, {alpha} is the toroidal angle, {alpha} = {phi} {minus} {delta}({Psi},{phi},{chi}) is the toroidal angle, {delta}({Psi},{phi},{chi}) is periodic in {phi}, and the magnetic field is represented as {rvec B} = {del}{Psi} {times} {del}{alpha}. A three-dimensional magnetospheric equilibrium code, the MAG-3D code, has been developed by employing an iterative metric method. The main difference between the three-dimensional and the two-dimensional axisymmetric solutions is that the field-aligned current and the toroidal magnetic field are finite for the three-dimensional case, but vanish for the two-dimensional axisymmetric case. With the same boundary flux surface shape, the two-dimensional axisymmetric results are similar to the three-dimensional magnetosphere at each local time cross section.

  13. A Cumulant-based Analysis of Nonlinear Magnetospheric Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Jay R. Johnson; Simon Wing

    2004-01-28

    Understanding magnetospheric dynamics and predicting future behavior of the magnetosphere is of great practical interest because it could potentially help to avert catastrophic loss of power and communications. In order to build good predictive models it is necessary to understand the most critical nonlinear dependencies among observed plasma and electromagnetic field variables in the coupled solar wind/magnetosphere system. In this work, we apply a cumulant-based information dynamical measure to characterize the nonlinear dynamics underlying the time evolution of the Dst and Kp geomagnetic indices, given solar wind magnetic field and plasma input. We examine the underlying dynamics of the system, the temporal statistical dependencies, the degree of nonlinearity, and the rate of information loss. We find a significant solar cycle dependence in the underlying dynamics of the system with greater nonlinearity for solar minimum. The cumulant-based approach also has the advantage that it is reliable even in the case of small data sets and therefore it is possible to avoid the assumption of stationarity, which allows for a measure of predictability even when the underlying system dynamics may change character. Evaluations of several leading Kp prediction models indicate that their performances are sub-optimal during active times. We discuss possible improvements of these models based on this nonparametric approach.

  14. Erosion of the inner magnetosphere during geomagnetic storms

    Directory of Open Access Journals (Sweden)

    E. Y. Feshchenko

    Full Text Available Using the empirical magnetic field model dependent on the Dst index and solar wind dynamic pressure, we calculated the behaviour of the contour B = Bs in the equatorial plane of the magnetosphere where Bs is the magnetic field in the subsolar point at the magnetopause. The inner domain of the magnetosphere outlined by this contour contains the bulk of geomagnetically trapped particles. During quiet time the boundary of the inner magnetosphere passes at the distance ~10 RE at noon and at ~7 RE at midnight. During very intense storms this distance can be reduced to 4–5 RE for all MLT. The calculation results agree well with the satellite measurements of the magnetopause location during storms. The ionospheric projection of the B = Bs contour calculated with the Euler potential technique is close to the equatorward edge of the auroral oval.

  15. Particle Energization During Magnetic Storms with Steady Magnetospheric Convection

    Science.gov (United States)

    Kissinger, J.; Kepko, L.; Baker, D. N.; Kanekal, S. G.; Li, W.; McPherron, R. L.; Angelopoulos, V.

    2013-12-01

    Relativistic electrons pose a space weather hazard to satellites in the radiation belts. Although about half of all geomagnetic storms result in relativistic electron flux enhancements, other storms decrease relativistic electron flux, even under similar solar wind drivers. Radiation belt fluxes depend on a complex balance between transport, loss, and acceleration. A critically important aspect of radiation belt enhancements is the role of the 'seed' population--plasma sheet particles heated and transported Earthward by magnetotail processes--which can become accelerated by wave-particle interactions with chorus waves. While the effect of substorms on seed electron injections has received considerable focus, in this study we explore how quasi-steady convection during steady magnetospheric convection (SMC) events affects the transport and energization of electrons. SMC events are long-duration intervals of enhanced convection without any substorm expansions, and are an important mechanism in coupling magnetotail plasma populations to the inner magnetosphere. We detail the behavior of the seed electron population for stormtime SMC events using the Van Allen Probes in the outer radiation belt and THEMIS in the plasma sheet and inner magnetosphere. Together, the two missions provide the ability to track particle transport and energization from the plasma sheet into the radiation belts. We present SMC events with Van Allen Probes/THEMIS conjunctions and compare plasma sheet fast flows/enhanced transport to radiation belt seed electron enhancements. Finally we utilize statistical analyses to quantify the relative importance of SMC events on radiation belt electron acceleration in comparison to isolated substorms.

  16. Riemann solvers and Alfven waves in black hole magnetospheres

    Science.gov (United States)

    Punsly, Brian; Balsara, Dinshaw; Kim, Jinho; Garain, Sudip

    2016-09-01

    In the magnetosphere of a rotating black hole, an inner Alfven critical surface (IACS) must be crossed by inflowing plasma. Inside the IACS, Alfven waves are inward directed toward the black hole. The majority of the proper volume of the active region of spacetime (the ergosphere) is inside of the IACS. The charge and the totally transverse momentum flux (the momentum flux transverse to both the wave normal and the unperturbed magnetic field) are both determined exclusively by the Alfven polarization. Thus, it is important for numerical simulations of black hole magnetospheres to minimize the dissipation of Alfven waves. Elements of the dissipated wave emerge in adjacent cells regardless of the IACS, there is no mechanism to prevent Alfvenic information from crossing outward. Thus, numerical dissipation can affect how simulated magnetospheres attain the substantial Goldreich-Julian charge density associated with the rotating magnetic field. In order to help minimize dissipation of Alfven waves in relativistic numerical simulations we have formulated a one-dimensional Riemann solver, called HLLI, which incorporates the Alfven discontinuity and the contact discontinuity. We have also formulated a multidimensional Riemann solver, called MuSIC, that enables low dissipation propagation of Alfven waves in multiple dimensions. The importance of higher order schemes in lowering the numerical dissipation of Alfven waves is also catalogued.

  17. Width of Injection/Dispersion Events in Saturn's Inner Magnetosphere

    Science.gov (United States)

    Chen, Y.; Hill, T. W.

    2008-05-01

    Longitudinally localized injection and drift dispersion of hot plasma are frequently observed by the Cassini Plasma Spectrometer (CAPS) and the Cassini Magnetospheric Imaging Instrument (MIMI) in Saturn's magnetosphere. These signatures provide direct evidence for the major convective process in the inner magnetosphere of a rapidly rotating planet, in which the radial transport of plasma is expected to comprise hot, tenuous plasma moving inward and cooler, denser plasma moving outward. Previous analyses of Cassini plasma observations are consistent with this scenario, but suggest further that the hot inflow sectors are significantly narrower than the adjacent cooler outflow sectors, a property that was not anticipated theoretically. Here we quantify this property by calculating the fraction of the available time that is occupied by injection structures in a two-year data set containing 429 such structures. This fraction is found to be small, typically ~ 3 - 7%, with no obvious dependence on SKR longitude. We will expand our data set by including the very young injection events discussed by Burch et al. [2005 GRL], which were excluded by the selection criteria in our previous study.

  18. Influence of magnetospheric inputs definition on modeling of ionospheric storms

    Science.gov (United States)

    Tashchilin, A. V.; Romanova, E. B.; Kurkin, V. I.

    Usually for numerical modeling of ionospheric storms corresponding empirical models specify parameters of neutral atmosphere and magnetosphere. Statistical kind of these models renders them impractical for simulation of the individual storm. Therefore one has to correct the empirical models using various additional speculations. The influence of magnetospheric inputs such as distributions of electric potential, number and energy fluxes of the precipitating electrons on the results of the ionospheric storm simulations has been investigated in this work. With this aim for the strong geomagnetic storm on September 25, 1998 hour global distributions of those magnetospheric inputs from 20 to 27 September were calculated by the magnetogram inversion technique (MIT). Then with the help of 3-D ionospheric model two variants of ionospheric response to this magnetic storm were simulated using MIT data and empirical models of the electric fields (Sojka et al., 1986) and electron precipitations (Hardy et al., 1985). The comparison of the received results showed that for high-latitude and subauroral stations the daily variations of electron density calculated with MIT data are more close to observations than those of empirical models. In addition using of the MIT data allows revealing some peculiarities in the daily variations of electron density during strong geomagnetic storm. References Sojka J.J., Rasmussen C.E., Schunk R.W. J.Geophys.Res., 1986, N10, p.11281. Hardy D.A., Gussenhoven M.S., Holeman E.A. J.Geophys.Res., 1985, N5, p.4229.

  19. Earth's polar cap ionization patches lead to ion upflow

    Science.gov (United States)

    Zhang, Q. H.; Zong, Q.; Lockwood, M. M.; Liang, J.; Zhang, B.; Moen, J. I.; Zhang, S.; Zhang, Y.; Ruohoniemi, J. M.; Thomas, E. G.; Liu, R.; Dunlop, M. W.; Yang, H. G.; Hu, H.; Liu, Y.; Lester, M.

    2014-12-01

    The Earth constantly losses matter through ions escaping from the polar ionosphere. This makes the ionosphere as an important source of plasma for the magnetosphere and could modulate atmospheric isotope abundances on geological timescales, depending on what fraction of the upflowing ions subsequently return to the ionosphere and what fraction are ejected into interplanetary space. It has been proposed that the magnetosphere is dynamically modulated by the presence of the ionospheric ions, particularly heavy ions O+, during magnetic substorms and storms. The origin and formation mechanism of ionospheric ion upflow is, however, poorly understood, particularly under disturbed space weather conditions. We report simultaneous direct observations of ion upflow and a patch of ionization at the center of the polar cap region during a geomagnetic storm. Our observations indicate enhanced fluxes of upwelling O+ ions originate from the patch and were accelerated by the enhanced ambipolar electric field. This enhancement is caused by soft electron precipitations. Polar cap patches therefore provide an important source of upwelling ions for accelerations mechanisms at greater altitudes which can eject the ions. These observations give new insight into the processes of ionosphere-magnetosphere coupling and the potential loss of terrestrial water dissociation products into space which, although extremely slow in the case of Earth, may be significant for other planets and moons.

  20. THEMIS measurements of quasi-static electric fields in the inner magnetosphere

    Science.gov (United States)

    Califf, S.; Li, X.; Blum, L.; Jaynes, A.; Schiller, Q.; Zhao, H.; Malaspina, D.; Hartinger, M.; Wolf, R. A.; Rowland, D. E.; Wygant, J. R.; Bonnell, J. W.

    2014-12-01

    We use 4 years of Time History of Events and Macroscale Interactions during Substorms (THEMIS) double-probe measurements to offer, for the first time, a complete picture of the dawn-dusk electric field covering all local times and radial distances in the inner magnetosphere based on in situ equatorial observations. This study is motivated by the results from the CRRES mission, which revealed a local maximum in the electric field developing near Earth during storm times, rather than the expected enhancement at higher L shells that is shielded near Earth as suggested by the Volland-Stern model. The CRRES observations were limited to the duskside, while THEMIS provides complete local time coverage. We show strong agreement with the CRRES results on the duskside, with a local maximum near L = 4 for moderate levels of geomagnetic activity and evidence of strong electric fields inside L = 3 during the most active times. The extensive data set from THEMIS also confirms the day/night asymmetry on the duskside, where the enhancement is closest to Earth in the dusk-midnight sector, and is farther away closer to noon. A similar, but smaller in magnitude, local maximum is observed on the dawnside near L = 4. The noon sector shows the smallest average electric fields, and for more active times, the enhancement develops near L = 7 rather than L = 4. We also investigate the impact of the uncertain boom-shorting factor on the results and show that while the absolute magnitude of the electric field may be underestimated, the trends with geomagnetic activity remain intact.

  1. Observational evidence of cavity modes in the earth's magnetosphere

    Energy Technology Data Exchange (ETDEWEB)

    Crowley, G. (National Center for Atmospheric Research, Boulder, CO (United States)); Hughes, W.J. (Boston Univ., MA (United States)); Jones, T.B. (Univ. of Leicester (England))

    1987-11-01

    On November 30, 1982, two large-amplitude Pc 5 pulsations were observed at Tromso, Norway, by both the European Incoherent Scatter (EISCAT) radar and ground-based magnetometers. The pulsations were excited by a sudden impulse. Their amplitude subsequently decreased, allowing a damping rate to be determined. Estimates of the height-integrated Pedersen conductivity obtained from the EISCAT data permit theoretical pulsation damping rates to be predicted. However, the theoretical damping rates are much greater than those actually measured, which indicates that energy was continuously fed into the field line resonance after its onset. The most likely source of this energy is coupling from a hydromagnetic cavity mode. If this is the case, the measured pulsation damping rate is controlled by the damping of the cavity mode rather than energy dissipation from the field lines resonance. An upper limit of {gamma}/{omega} = 0.08 is obtained from the coupling efficiency between the two modes. The energy dissipated in the ionosphere by these pulsations was {approximately}4 {times} 10{sup 12} J. To store this energy in the cavity mode requires an initial cavity mode amplitude of only {approximately}0.4 nT. Long-period magnetic perturbations of this amplitude would be difficult to detect in existing spaceborne magnetometer data sets.

  2. A Time-Dependent Three-Dimensional Simulation of the Earth’s Magnetosphere: Reconnection Events.

    Science.gov (United States)

    1981-12-22

    10027 C. Wharton Attn: R. Taussig F. Horse R. A. Gross R. Lovelace 35 Harvard University Uorthvestern University Cambridge, Massachusetts 02138 Evanston...Phoenix Corp. 20 Demar Road 1600 Anderson Road Lexington, Maryland 02173 McLean, VirgJnia 22102 Gendrin, Roger Schulz, Michael . CNET Aerospace Corp. 3...Physics & Astronomy Observatoire University of Iowa D.A.F. C21GO Iowa City, Iowa 52242 Meudon, FRANCE Temerin, Michael Space. Science Lab. Kikuchi

  3. Auroral electrojets and boundaries of plasma domains in the magnetosphere during magnetically disturbed intervals

    Directory of Open Access Journals (Sweden)

    Y. I. Feldstein

    2006-09-01

    Full Text Available We investigate variations in the location and intensity of the auroral electrojets during magnetic storms and substorms using a numerical method for estimating the equivalent ionospheric currents based on data from meridian chains of magnetic observatories. Special attention was paid to the complex structure of the electrojets and their interrelationship with diffuse and discrete particle precipitation and field-aligned currents in the dusk sector. During magnetospheric substorms the eastward electrojet (EE location in the evening sector changes with local time from cusp latitudes (Φ~77° during early afternoon to latitudes of diffuse auroral precipitation (Φ~65° equatorward of the auroral oval before midnight. During the main phase of an intense magnetic storm the eastward currents in the noon-early evening sector adjoin to the cusp at Φ~65° and in the pre-midnight sector are located at subauroral latitude Φ~57°. The westward electrojet (WE is located along the auroral oval from evening through night to the morning sector and adjoins to the polar electrojet (PE located at cusp latitudes in the dayside sector. The integrated values of the eastward (westward equivalent ionospheric current during the intense substorm are ~0.5 MA (~1.5 MA, whereas they are 0.7 MA (3.0 MA during the storm main phase maximum. The latitudes of auroral particle precipitation in the dusk sector are identical with those of both electrojets. The EE in the evening sector is accompanied by particle precipitation mainly from the Alfvén layer but also from the near-Earth part of the central plasma sheet. In the lower-latitude part of the EE the field-aligned currents (FACs flow into the ionosphere (Region 2 FAC, and at its higher-latitude part the FACs flow out of the ionosphere (Region 1 FAC. During intense disturbances, in addition to the Region 2 FAC and the Region 1 FAC, a Region 3 FAC with the downward current was identified. This FAC is accompanied by diffuse

  4. Energetic Particle Spectral Shapes in Planetary Magnetospheres; Assessment of the Kappa Function

    Science.gov (United States)

    Mauk, B.

    2015-12-01

    In assessing the efficacy of the kappa distribution function in space environments, it is useful to follow two paths. First, to what extent do we consider the kappa function (or any function) to represent some kind of universal spectral shape that indicates common physical processes occurring in a wide diversity of space environments? Second, how useful is the kappa function in quantitatively characterizing observed spectral shapes, particularly for the purpose permitting further quantitative analyses of the environment (e. g. wave growth). In this report I evaluate the efficacy of the kappa distribution in representing energetic particle spectral shapes in planetary magnetospheres from both perspectives. In particular, I expand on the extensive treatment provided by Carbary et al. (2014) by taking a more explicit comparative approach between the different planets (Earth, Jupiter, Saturn, Uranus, and Neptune) and also focusing on the most intense (and therefore from my perspective the most interesting) spectra within each of these different planets. There is no question that the "power law tail" represents as close to a universal characteristic of planetary space environments as one could hope to find. Such a universal shape must represent some universality in the energization and/or equilibrating processes. Also, there is no question that such tails must (to be non-divergent) and do roll over to flatter shapes at lower energies. In a number of applications, this basic characteristic has been usefully characterized by the kappa function to extract such parameters of the system as flow velocities. However, at least for the more intense spectra at Earth, Jupiter, Saturn, and Uranus, the kappa function in fact does a relatively poor job in representing the low energy roll-over of energetic particle spectra. Other functional forms have been found to be much more useful for characterizing these spectral shapes over a broad range of energies. And specifically, a very

  5. Magnetosphere-ionosphere coupling currents in Jupiter's middle magnetosphere: effect of magnetosphere-ionosphere decoupling by field-aligned auroral voltages

    Directory of Open Access Journals (Sweden)

    J. D. Nichols

    2005-03-01

    Full Text Available We consider the effect of field-aligned voltages on the magnetosphere-ionosphere coupling current system associated with the breakdown of rigid corotation of equatorial plasma in Jupiter's middle magnetosphere. Previous analyses have assumed perfect mapping of the electric field and flow along equipotential field lines between the equatorial plane and the ionosphere, whereas it has been shown that substantial field-aligned voltages must exist to drive the field-aligned currents associated with the main auroral oval. The effect of these field-aligned voltages is to decouple the flow of the equatorial and ionospheric plasma, such that their angular velocities are in general different from each other. In this paper we self-consistently include the field-aligned voltages in computing the plasma flows and currents in the system. A third order differential equation is derived for the ionospheric plasma angular velocity, and a power series solution obtained which reduces to previous solutions in the limit that the field-aligned voltage is small. Results are obtained to second order in the power series, and are compared to the original zeroth order results with no parallel voltage. We find that for system parameters appropriate to Jupiter the effect of the field-aligned voltages on the solutions is small, thus validating the results of previously-published analyses.

  6. Wave energy budget analysis in the Earth's radiation belts uncovers a missing energy.

    Science.gov (United States)

    Artemyev, A V; Agapitov, O V; Mourenas, D; Krasnoselskikh, V V; Mozer, F S

    2015-05-15

    Whistler-mode emissions are important electromagnetic waves pervasive in the Earth's magnetosphere, where they continuously remove or energize electrons trapped by the geomagnetic field, controlling radiation hazards to satellites and astronauts and the upper-atmosphere ionization or chemical composition. Here, we report an analysis of 10-year Cluster data, statistically evaluating the full wave energy budget in the Earth's magnetosphere, revealing that a significant fraction of the energy corresponds to hitherto generally neglected very oblique waves. Such waves, with 10 times smaller magnetic power than parallel waves, typically have similar total energy. Moreover, they carry up to 80% of the wave energy involved in wave-particle resonant interactions. It implies that electron heating and precipitation into the atmosphere may have been significantly under/over-valued in past studies considering only conventional quasi-parallel waves. Very oblique waves may turn out to be a crucial agent of energy redistribution in the Earth's radiation belts, controlled by solar activity.

  7. Existence of a component corotating with the earth in high-latitude disturbance magnetic fields

    Science.gov (United States)

    Suzuki, A.; Kim, J. S.; Sugiura, M.

    1982-01-01

    A study of the data from the high-latitude North American IMS network of magnetic stations suggests that there is a component in substorm perturbations that corotates with the earth. It is as yet not certain whether the existence of this component stems from the corotation of a part of the magnetospheric plasma involved in the substorm mechanism or if it is a 'phase change' resulting from the control of the substorm manifestations by the earth's main magnetic field which is not axially symmetric. There are other geophysical phenomena showing a persistence of longitudinal variations corotating with the earth. These phenomena are of significance for a better understanding of ionosphere-magnetosphere coupling.

  8. Spinning, Breathing, and Flapping: Ion Periodicities in Saturn's Middle Magnetosphere

    Science.gov (United States)

    Ramer, K. M.; Kivelson, M.; Khurana, K. K.; Jia, X.; Sergis, N.; Walker, R. J.

    2013-12-01

    In Saturn's magnetosphere, periodic fluctuations are ubiquitous; for example, periodicities have been observed in Saturn Kilometric Radiation (SKR), in auroral emissions, the magnetic field, electron density, and energetic particle fluxes. In previous work, we extended earlier investigations of periodicities near Saturn's equatorial plane from 6 to 15 RS, determining that ion pressure, magnetic pressure, velocity, and ion density perturbations are roughly modulated at the SLS period. However, the phase relationships obtained in this analysis were confusing and the large scatter inherent in the data led us to question results that suggested significant differences from one radial and local time bin to the next in the phases at which perturbations peaked. In this work, we use an MHD simulation by Jia et al. [2012], which posits rotating vortices in the ionosphere, to put our initial results into context, leading to a deeper understanding of magnetospheric processes and the data returned by Cassini. The simulation shows compellingly that periodicities in field and plasma properties arise from a combination of rotational and compressional perturbations. For example, the magnetic pressure perturbations systematically rotate at the SLS period in the middle magnetosphere. When SLS phase near noon is 250°, near noon at 7.5 Rs the data show that the magnetic pressure perturbation is maximum whereas the ion pressure perturbations are near minimum. The simulation allows us to argue that these anticorrelated extrema occur at the phase of maximum magnetospheric compression when the magnetic field of the dayside plasma sheet in the middle magnetosphere is most dipolarized. At this phase, plasma is not confined to the equator but is distributed along the flux tube; in the resulting thick plasma sheet, the equatorial pressure drops to its lowest value. At the same rotation phase at midnight, near 7.5 Rs the data show that the magnetic pressure is at a minimum and is

  9. New approaches to explore the Earth's magnetic field

    DEFF Research Database (Denmark)

    Olsen, Nils; Moretto, T.; Friis-Christensen, Eigil

    2002-01-01

    New strategies are presented for the analysis of the high-precision geomagnetic data that are currently obtained by the low-orbiting satellites Orsted, CHAMP and Orsted-2/SAC-C. The measured magnetic field is the sum of contributions from various sources in the core, crust, ionosphere...... and magnetosphere, and the accuracy of core and crustal field models is affected by ionospheric and magnetospheric source contributions. A proper parameterization of these external sources, together with a careful data pre-selection, is necessary to avoid spurious effects. In addition, the advantage of having...... multiple satellite missions measuring simultaneously over different regions of the Earth is discussed, and swarm, a proposed constellation consisting of 6 satellites in two different orbit planes, is presented....

  10. Definition of Saturn's magnetospheric model parameters for the Pioneer 11 flyby

    Directory of Open Access Journals (Sweden)

    E. S. Belenkaya

    2006-05-01

    Full Text Available This paper presents a description of a method for selection parameters for a global paraboloid model of Saturn's magnetosphere. The model is based on the preexisting paraboloid terrestrial and Jovian models of the magnetospheric field. Interaction of the solar wind with the magnetosphere, i.e. the magnetotail current system, and the magnetopause currents screening all magnetospheric field sources, is taken into account. The input model parameters are determined from observations of the Pioneer 11 inbound flyby.

  11. Generation of high-energy particles, neutrino and fotons in magnetosphere of collapsing star

    Directory of Open Access Journals (Sweden)

    Kryvdyk Volodymyr

    2014-04-01

    Full Text Available The generation of particles, photons and neutrinos in magnetosphere of collapsing star are considered. These processes are caused the self-interaction initial accelerating in magnetosphere protons and electrons. The second particles and photons will arise as a result of this self-interaction, which in turn will generate charged particles, photons and neutrino (cascade process. These processes are especially effective for the formation collapsing star magnetosphere from the secondary charged particles. In addition, the particles, photons and neutrinos will be generated in magnetosphere of collapsing star as result of these processes.

  12. Modeling the ionosphere-thermosphere response to a geomagnetic storm using physics-based magnetospheric energy input: OpenGGCM-CTIM results

    Directory of Open Access Journals (Sweden)

    Connor Hyunju Kim

    2016-01-01

    Full Text Available The magnetosphere is a major source of energy for the Earth’s ionosphere and thermosphere (IT system. Current IT models drive the upper atmosphere using empirically calculated magnetospheric energy input. Thus, they do not sufficiently capture the storm-time dynamics, particularly at high latitudes. To improve the prediction capability of IT models, a physics-based magnetospheric input is necessary. Here, we use the Open Global General Circulation Model (OpenGGCM coupled with the Coupled Thermosphere Ionosphere Model (CTIM. OpenGGCM calculates a three-dimensional global magnetosphere and a two-dimensional high-latitude ionosphere by solving resistive magnetohydrodynamic (MHD equations with solar wind input. CTIM calculates a global thermosphere and a high-latitude ionosphere in three dimensions using realistic magnetospheric inputs from the OpenGGCM. We investigate whether the coupled model improves the storm-time IT responses by simulating a geomagnetic storm that is preceded by a strong solar wind pressure front on August 24, 2005. We compare the OpenGGCM-CTIM results with low-earth-orbit satellite observations and with the model results of Coupled Thermosphere-Ionosphere-Plasmasphere electrodynamics (CTIPe. CTIPe is an up-to-date version of CTIM that incorporates more IT dynamics such as a low-latitude ionosphere and a plasmasphere, but uses empirical magnetospheric input. OpenGGCM-CTIM reproduces localized neutral density peaks at ~ 400 km altitude in the high-latitude dayside regions in agreement with in situ observations during the pressure shock and the early phase of the storm. Although CTIPe is in some sense a much superior model than CTIM, it misses these localized enhancements. Unlike the CTIPe empirical input models, OpenGGCM-CTIM more faithfully produces localized increases of both auroral precipitation and ionospheric electric fields near the high-latitude dayside region after the pressure shock and after the storm onset

  13. Volcanic activity on Io and its influence on the dynamics of the Jovian magnetosphere observed by EXCEED/Hisaki in 2015

    Science.gov (United States)

    Yoshikawa, Ichiro; Suzuki, Fumiharu; Hikida, Reina; Yoshioka, Kazuo; Murakami, Go; Tsuchiya, Fuminori; Tao, Chihiro; Yamazaki, Atsushi; Kimura, Tomoki; Kita, Hajime; Nozawa, Hiromasa; Fujimoto, Masaki

    2017-08-01

    Jupiter's moon Io, which orbits deep inside the magnetosphere, is the most geologically active object in the solar system. Kurdalagon Patera, a volcano on Io, erupted in 2015 and became a substantial source of Jovian magnetospheric plasma. Based on Earth-orbiting spacecraft observations, Io plasma torus (IPT) exhibited the peak intensity (nearly double) of ionic sulfur emissions roughly 2 month later, followed by a decay phase. This environmental change provides a unique opportunity to determine how the more heavily loaded magnetosphere behaves. Indeed, the extreme ultraviolet spectroscope for exospheric dynamics onboard the Earth-orbiting spacecraft Hisaki witnessed the whole interval via aurora and IPT observations. A simple-minded idea would be that the centrifugal force acting on fast co-rotating magnetic flux tubes loaded with heavier contents intensifies their outward transport. At the same time, there must be increased inward convection to conserve the magnetic flux. The latter could be accompanied by (1) increased inward velocity of field lines, (2) increased frequency of inward transport events, (3) increased inward flux carried per event, or (4) combinations of them. The Hisaki observations showed that the densities of major ions in the IPT increased and roughly doubled compared with pre-eruption values. The hot electron fraction, which sustains the EUV radiation from the IPT, gradually increased on a timescale of days. Pairs of intensified aurora and IPT brightening due to the enhanced supply of hot electrons from the mid-magnetosphere to the IPT upon aurora explosions observed during both quiet and active times, enabled the study of the mid-magnetosphere/IPT relationship. Hisaki observations under active Io conditions showed that: (1) the hot electron fraction in the torus gradually increased; (2) brightening pairs were more intense; (3) the energy supplied by the largest event maintained enhanced torus emission for less than a day; (4) the time delay

  14. Magnetospheric Multiscale Satellite Observations of Parallel Electron Acceleration in Magnetic Field Reconnection by Fermi Reflection from Time Domain Structures.

    Science.gov (United States)

    Mozer, F S; Agapitov, O A; Artemyev, A; Burch, J L; Ergun, R E; Giles, B L; Mourenas, D; Torbert, R B; Phan, T D; Vasko, I

    2016-04-08

    The same time domain structures (TDS) have been observed on two Magnetospheric Multiscale Satellites near Earth's dayside magnetopause. These TDS, traveling away from the X line along the magnetic field at 4000  km/s, accelerated field-aligned ∼5  eV electrons to ∼200  eV by a single Fermi reflection of the electrons by these overtaking barriers. Additionally, the TDS contained both positive and negative potentials, so they were a mixture of electron holes and double layers. They evolve in ∼10  km of space or 7 ms of time and their spatial scale size is 10-20 km, which is much larger than the electron gyroradius (<1  km) or the electron inertial length (4 km at the observation point, less nearer the X line).

  15. A Kalman Filter for Mass Property and Thrust Identification of the Spin-Stabilized Magnetospheric Multiscale Formation

    Science.gov (United States)

    Queen, Steven Z.

    2015-01-01

    The Magnetospheric Multiscale (MMS) mission consists of four identically instrumented, spin-stabilized observatories, elliptically orbiting the Earth in a tetrahedron formation. For the operational success of the mission, on-board systems must be able to deliver high-precision orbital adjustment maneuvers. On MMS, this is accomplished using feedback from on-board star sensors in tandem with accelerometers whose measurements are dynamically corrected for errors associated with a spinning platform. In order to determine the required corrections to the measured acceleration, precise estimates of attitude, rate, and mass-properties are necessary. To this end, both an on-board and ground-based Multiplicative Extended Kalman Filter (MEKF) were formulated and implemented in order to estimate the dynamic and quasi-static properties of the spacecraft.

  16. Correlation between convection electric fields in the nightside magnetosphere and several wave and particle phenomena during two isolated substorms.

    Science.gov (United States)

    Carpenter, D. L.; Fraser-Smith, A. C.; Unwin, R. S.; Hones, E. W., Jr.; Heacock, R. R.

    1971-01-01

    Correlation of several magnetoionospheric wave and particle phenomena previously linked observationally to magnetospheric substorms and inferred to involve convection electric fields with whistler measurements of convection activity during two relatively isolated substorms. The events occurred at about 0600 UT on July 15, 1965, and about 0500 UT on Oct. 13, 1965. The correlated phenomena include cross-L inward plasma drifts near midnight within the plasmaphere, diffuse auroral radar echoes observed near the dusk meridian, IPDP micropulsations (intervals of pulsations of diminishing period) in the premidnight sector, apparent contractions and expansions of the plasma sheet at about 20 earth radii in the magnetotail, and Pc 1/Pi 1 micropulsation events near or before midnight. Two new vlf phenomena occurred during the October 13 event - a noise band within the plasmasphere associated with a convecting whistler path, and ?hisslers,' falling-tone auroral-hiss forms repeated at intervals of about 2 sec.

  17. Bifurcation and Hysteresis of the Magnetospheric Structure with a varying Southward IMF: Field Topology and Global Three-dimensional Full Particle Simulations

    Science.gov (United States)

    Cai, DongSheng; Tao, Weinfeng; Yan, Xiaoyang; Lembege, Bertrand; Nishikawa, Ken-Ichi

    2007-01-01

    Using a three-dimensional full electromagnetic particle model (EMPM), we have performed global simulations of the interaction between the solar wind and the terrestrial magnetosphere, and have investigated its asymptotic stability. The distance between the dayside magnetopause subsolar point and the Earth center, R(sub mp) is measured, as the intensity of southward IMF |B(sub z)| is slowly varying. Based on the field topology theory, one analyzes the variation of R(sub mp) as a reference index of the dynamics of this interaction, when IMF |B(sub z)| successively increases and decreases to its original value. Two striking results are observed. First, as the IMF |B(sub z)| increases above a critical value, the variation of R(sub mp) suddenly changes (so called 'bifurcation' process in field topology). Above this critical value, the overall magnetic field topology changes drastically and is identified as being the signature of magnetic reconnection at the subsolar point on the magnetopause. Second, this subsolar point recovers its original location R(sub mp) by following different paths as the IMF |B(sub z)| value increases (from zero to a maximum fixed value) and decreases (from this maximum to zero) passing through some critical values. These different paths are the signature of 'hysteresis' effect, and are characteristic of the so-called 'subcritical-type' bifurcation. This hysteresis signature indicates that dissipation processes take place via an energy transfer from the solar wind to the magnetosphere by some irreversible way, which leads to a drastic change in the magnetospheric field topology. This hysteresis is interpreted herein as a consequence of the magnetic reconnection taking place at the dayside magnetopause. The field topology reveals to be a very powerful tool to analyze the signatures of three-dimensional magnetic reconnection without the obligation for determining the mechanisms responsible for, and the consequences of the reconnection on the

  18. Access of solar wind electrons into the Martian magnetosphere

    Directory of Open Access Journals (Sweden)

    E. M. Dubinin

    2008-11-01

    Full Text Available Electrons with energy of ~40–80 eV measured by the instrument ASPERA-3 on Mars Express and MAG-ER onboard Mars Global Surveyor are used to trace an access of solar wind electrons into the Martian magnetosphere. Crustal magnetic fields create an additional protection from solar wind plasma on the dayside of the Southern Hemisphere by shifting the boundary of the induced magnetosphere (this boundary is often refereed as the magnetic pileup boundary above strong crustal sources to ~400 km as compared to the Northern Hemisphere. Localized intrusions through cusps are also observed. On the nightside an access into the magnetosphere depends on the IMF orientation. Negative values of the ByIMF component assist the access to the regions with strong crustal magnetizations although electron fluxes are strongly weakened below ~600 km. A precipitation pattern at lower altitudes is formed by intermittent regions with reduced and enhanced electron fluxes. The precipitation sites are longitudinally stretched narrow bands in the regions with a strong vertical component of the crustal field. Fluxes ≥109 cm−2 s−1 of suprathermal electrons necessary to explain the observed aurora emissions are maintained only for the periods with enhanced precipitation. The appearance of another class of electron distributions – inverted V structures, characterized by peaks on energy spectra, is controlled by the IMF. They are clustered in the hemisphere pointed by the interplanetary electric field that implies a constraint on their origin.

  19. Five Years of Stereo Magnetospheric Imaging by TWINS

    Science.gov (United States)

    Goldstein, J.; McComas, D. J.

    2013-12-01

    Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS) is the first stereoscopic magnetospheric imager. TWINS is a NASA Explorer Mission of Opportunity performing simultaneous energetic neutral atom (ENA) imaging from two widely-separated Molniya orbits on two different spacecraft, and providing nearly continuous coverage of magnetospheric ENA emissions. The ENA imagers observe energetic neutrals produced from global ion populations, over a broad energy range (1-100 keV/u) with high angular (4∘×4∘) and time (about 1-minute) resolution. TWINS distinguishes hydrogen ENAs from oxygen ENAs. Each TWINS spacecraft also carries a Lyman- α geocoronal imager to monitor the cold exospheric hydrogen atoms that produce ENAs from ions via charge exchange. Complementing the imagers are detectors that measure the local charged particle environment around the spacecraft. During its first five years of science operations, TWINS has discovered new global properties of geospace plasmas and neutrals, fostered understanding of causal relationships, confirmed theories and predictions based on in situ data, and yielded key insights needed to improve geospace models. Analysis and modeling of TWINS data have: (1) obtained continuous (main phase through recovery) global ion spectra, (2) revealed a previously unknown local-time dependence of global pitch angle, (3) developed quantitative determination of ion fluxes from low altitude ENAs (4) determined dynamic connections between local pitch angle and global ion precipitation, (5) confirmed local-time dependence of precipitating ion temperature, (6) imaged global dynamic heating of the magnetosphere, (7) explained why the oxygen ring current survives longer into recovery than hydrogen, and (8) revealed new global exospheric density features and their influence upon ring current decay rates. Over the next several years of the solar cycle, TWINS observations of three-dimensional (3D) global ion dynamics, composition, origins and

  20. Investigating Fresh Hot Plasma Injections in Saturn's Inner-Magnetosphere

    Science.gov (United States)

    Vandegriff, J. D.; Loftus, K.; Rymer, A. M.; Mitchell, D. G.

    2015-12-01

    A decreasing density gradient in Saturn's plasma disk allows for centrifugal interchange instability between the dense, heavy plasma inside 10 Rs and the lighter plasma outside. This instability results in the less dense plasma of the mid-magnetosphere moving inward to the inner-magnetosphere. As flux tubes move inward, their volume decreases, and the contained plasma heats adiabatically. Most studies of interchange have focused on older events that have had time to gradient and curvature drift such that they are easily identified by a characteristic "V" energy dispersion signature in the ion and electron data [e.g. Hill et al., 2005; Chen et al., 2010]. Recently, Kennelly et al. (2013) used radio wave data to identify >300 possible "fresh" injection events. These are characterized in the plasma data by a bite-out at low energies, an enhancement at high energies, and little to no energy dispersion. Our study builds on the Kennelly et al. study to investigate the shape and frequency of injection events in order to better characterize how hot plasma transports into the inner magnetosphere. In most models of centrifugal interchange at Saturn, the time and spatial scales for inward and outward transport are fairly symmetric, but Cassini data suggests that inward injections of plasma move at much greater velocity and in narrower flow channels than their outgoing counterparts. Here we investigate the morphology of Kronian inward injection events to see if our dataset of young injections can inform on whether the inward injections are extended fingers or more like "bubbles", isolated flux tubes. Specifically, we apply minimum variance analysis to Cassini magnetic field data to determine the boundary normals at the spacecraft's entrance and exit points for each event, from which we can statistically analyze the structure's cross section. We will present our initial results on the morphology as well as the distribution of the injections over radial distance, latitude, and

  1. The importance of ground magnetic data in specifying the state of magnetosphere-ionosphere coupling: a personal view

    Science.gov (United States)

    Kamide, Y.; Balan, Nanan

    2016-12-01

    In the history of geomagnetism, geoelectricity and space science including solar terrestrial physics, ground magnetic records have been demonstrated to be a powerful tool for monitoring the levels of overall geomagnetic activity. For example, the Kp and ap indices having perhaps the long-history geomagnetic indices have and are being used as space weather parameters, where "p" stands for "planetary" implying that these indices express average geomagnetic disturbances on the entire Earth in a planetary scale. To quantify the intensity level of geomagnetic storms, however, it is common to rely on the Dst index, which is supposed to show the magnitude of the storm-time ring current. Efforts were also made to inter-calibrate various activity indices. Different indices were proposed to express different aspects of a phenomenon in the near-Earth space. In the early 1980s, several research groups in Japan, Russia, Europe and the US developed the so-called magnetogram-inversion techniques, which were proposed all independently. Subsequent improvements of the magnetogram-inversion algorithms allowed their technology to be applied to a number of different datasets for magnetospheric convection and substorms. In the present review, we demonstrate how important it was to make full use of ground magnetic data covering a large extent in both latitudinal and longitudinal directions. It is now possible to map a number of electrodynamic parameters in the polar ionosphere on an instantaneous basis. By applying these new inverse methods to a number of ground-based geomagnetic observations, it was found that two basic elements in spatial patterns can be viewed as two physical processes for solar wind-magnetosphere energy coupling.

  2. Global Positioning System Navigation Above 76,000 km for NASA's Magnetospheric Multiscale Mission

    Science.gov (United States)

    Winternitz, Luke B.; Bamford, William A.; Price, Samuel R.; Carpenter, J. Russell; Long, Anne C.; Farahmand, Mitra

    2016-01-01

    NASA's Magnetospheric Multiscale (MMS) mission, launched in March of 2015, consists of a controlled formation of four spin-stabilized spacecraft in similar highly elliptic orbits reaching apogee at radial distances of 12 and 25 Earth radii (RE) in the first and second phases of the mission. Navigation for MMS is achieved independently on-board each spacecraft by processing Global Positioning System (GPS) observables using NASA Goddard Space Flight Center (GSFC)'s Navigator GPS receiver and the Goddard Enhanced Onboard Navigation System (GEONS) extended Kalman filter software. To our knowledge, MMS constitutes, by far, the highest-altitude operational use of GPS to date and represents a high point of over a decade of high-altitude GPS navigation research and development at GSFC. In this paper we will briefly describe past and ongoing high-altitude GPS research efforts at NASA GSFC and elsewhere, provide details on the design of the MMS GPS navigation system, and present on-orbit performance data from the first phase. We extrapolate these results to predict performance in the second phase orbit, and conclude with a discussion of the implications of the MMS results for future high-altitude GPS navigation, which we believe to be broad and far-reaching.

  3. Magnetospheric Multiscale Satellites Observations of Parallel Electric Fields Associated with Magnetic Reconnection.

    Science.gov (United States)

    Ergun, R E; Goodrich, K A; Wilder, F D; Holmes, J C; Stawarz, J E; Eriksson, S; Sturner, A P; Malaspina, D M; Usanova, M E; Torbert, R B; Lindqvist, P-A; Khotyaintsev, Y; Burch, J L; Strangeway, R J; Russell, C T; Pollock, C J; Giles, B L; Hesse, M; Chen, L J; Lapenta, G; Goldman, M V; Newman, D L; Schwartz, S J; Eastwood, J P; Phan, T D; Mozer, F S; Drake, J; Shay, M A; Cassak, P A; Nakamura, R; Marklund, G

    2016-06-10

    We report observations from the Magnetospheric Multiscale satellites of parallel electric fields (E_{∥}) associated with magnetic reconnection in the subsolar region of the Earth's magnetopause. E_{∥} events near the electron diffusion region have amplitudes on the order of 100  mV/m, which are significantly larger than those predicted for an antiparallel reconnection electric field. This Letter addresses specific types of E_{∥} events, which appear as large-amplitude, near unipolar spikes that are associated with tangled, reconnected magnetic fields. These E_{∥} events are primarily in or near a current layer near the separatrix and are interpreted to be double layers that may be responsible for secondary reconnection in tangled magnetic fields or flux ropes. These results are telling of the three-dimensional nature of magnetopause reconnection and indicate that magnetopause reconnection may be often patchy and/or drive turbulence along the separatrix that results in flux ropes and/or tangled magnetic fields.

  4. Statistical Features of EMIC Waves Observed on Van Allen Probes in the Inner Magnetosphere

    Science.gov (United States)

    Lee, D. Y.; Roh, S. J.; Cho, J.; Shin, D. K.; Hwang, J.; Kim, K. C.; Kurth, W. S.; Kletzing, C.; Wygant, J. R.; Thaller, S. A.

    2015-12-01

    Electromagnetic ion cyclotron (EMIC) waves are one of the key plasma waves that can affect charged particle dynamics in the Earth's inner magnetosphere. Knowledge of global distribution of the EMIC waves is critical for accurately assessing the significance of its interaction with charged particles. With the Van Allen Probes EMFISIS observations, we have surveyed EMIC events for ~2.5 years period. We have identified well-defined, banded wave activities only, as distinguished from broad band wave activities. We have obtained global distribution of occurrence of the identified waves with distinction between H- and He-bands. We compare it with previous observations such as THEMIS and CRRES. For the identified events we have drawn all the basic wave properties including wave frequency, polarization, wave normal angle. In addition, we have distinguished the EMIC events that occur inside the plasmasphere and at the plasmapause from those outside the plasmasphere. Finally, we have tested solar wind and geomagnetic dependence of the wave events. We give discussions about implications of these observations on wave generation mechanism and interaction with radiation belt electrons.

  5. An Extended Model for Interaction Between Left-hand Superluminous Waves and Magnetospheric Electrons

    Institute of Scientific and Technical Information of China (English)

    Xiao Fuliang; Zheng Huinan; Wang Shui

    2005-01-01

    The left-hand superluminous electromagnetic waves, L-O mode and L-X mode, can be excited and observed in the auroral cavity of the Earth during the magnetic storms. The two modes can propagate into outer radiation zone and encounter enhanced resonant interactions with the trapped energetic electrons over a wide range of magnetosphere. A current first-order resonant model is extended to evaluate the stochastic acceleration of electrons by the L-O mode and L-X mode at the higher-order resonance. Similar to the first-order resonance, L-O mode can produce significant acceleration of electrons at the higher harmonic resonances over a wide range of wave normal angles and spatial regions. However, the higher harmonic resonance's contribution for significant electron acceleration by L-X mode is less than that of the first order resonance,with the requirement of higher minimum energies, e.g., ~1 MeV in the outer radiation belt. This indicates that L-O mode may be one of the efficient mechanisms for the stochastic acceleration of electrons within the outer radiation zone.

  6. Influence of tail-like magnetic field on O+ ion distribution in the Martian magnetosphere

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on the comparison with the Earth, using the LB magneticfield model, the distribution of O+ ion originating from the ionosphere in the Martian magnetosphere is theoretically studied under different conditions of the tail-like magnetic field. The results show that the tail-like magnetic field has influence on the O+ ion flux in the Martian magnetotail: (ⅰ) the O+ ion flux in the Martian tail will increase if the tail-like magnetic field increases; when the tail-like magnetic field increases from 5 nT to 20 nT, the O+ ion flux increases 3 times in the region of 2.8 Rm in the Martian tail; and (ⅱ) the O+ ion flux decreases with increasing intrinsic moment; when the intrinsic moment increases about 5 times, the flux decreases to one fourth in the region of 2.8 Rm in the Martian tail. According to the data on the O+ ion flux and theoretical result in this paper, the deduced Martian intrinsic moment is about 2×1021 Gcm3. This is consistent with the most recent observation by the USA satellite MGS.

  7. The large-scale magnetospheric electric field observed by Double Star TC-1

    Directory of Open Access Journals (Sweden)

    C. Carr

    2010-09-01

    Full Text Available The relationship between the average structure of the inner magnetospheric large-scale electric field and geomagnetic activity levels has been investigated by Double Star TC-1 data for radial distances ρ between 4.5 RE and 12.5 RE and MLT between 18:00 h and 06:00 h from July to October in 2004 and 2005. The sunward component of the electric field decreases monotonically as ρ increases and approaches zero as the distance off the Earth is greater than 10 RE. The dawn-dusk component is always duskward. It decreases at about 6 RE where the ring current is typically observed to be the strongest and shows strong asymmetry with respect to the magnetic local time. Surprisingly, the average electric field obtained from TC-1 for low activity is almost comparable to that observed during moderate activity, which is always duskward at the magnetotail (8 RE~12 RE.

  8. Interactions between energetic electrons and realistic whistler mode waves in the Jovian magnetosphere

    Science.gov (United States)

    de Soria-Santacruz, M.; Shprits, Y. Y.; Drozdov, A.; Menietti, J. D.; Garrett, H. B.; Zhu, H.; Kellerman, A. C.; Horne, R. B.

    2017-05-01

    The role of plasma waves in shaping the intense Jovian radiation belts is not well understood. In this study we use a realistic wave model based on an extensive survey from the Plasma Wave Investigation on the Galileo spacecraft to calculate the effect of pitch angle and energy diffusion on Jovian energetic electrons due to upper and lower band chorus. Two Earth-based models, the Full Diffusion Code and the Versatile Electron Radiation Belt code, are adapted to the case of the Jovian magnetosphere and used to resolve the interaction between chorus and electrons at L = 10. We also present a study of the sensitivity to the latitudinal wave coverage and initial electron distribution. Our analysis shows that the contribution to the electron dynamics from upper band chorus is almost negligible compared to that from lower band chorus. For 100 keV electrons, we observe that diffusion leads to redistribution of particles toward lower pitch angles with some particle loss, which could indicate that radial diffusion or interchange instabilities are important. For energies above >500 keV, an initial electron distribution based on observations is only weakly affected by chorus waves. Ideally, we would require the initial electron phase space density before transport takes place to assess the importance of wave acceleration, but this is not available. It is clear from this study that the shape of the electron phase space density and the latitudinal extent of the waves are important for both electron acceleration and loss.

  9. Low Frequency Extensions of the Saturn Kilometric Radiation as a Proxy for Magnetospheric Dynamics.

    Science.gov (United States)

    Reed, J.; Jackman, C. M.; Whiter, D. K.; Kurth, W. S.; Lamy, L.

    2016-12-01

    Saturn Kilometric Radiation (SKR) is a radio emission formed via the cyclotron maser instability on field aligned currents near the auroral regions of Saturn. The SKR has been found to respond to both internal and external driving, and to be linked to both solar wind compressions and magnetotail reconnection events. The radio emission is remotely sensed quasi-continuously and therefore offers the potential to be used as a proxy for magnetospheric activity when the spacecraft is not in an ideal viewing region for observing signatures of reconnection. In this work we use data taken by the Cassini magnetometer and radio and plasma wave sensor while Cassini was executing its deepest tail orbits in 2006. We characterise the behaviour of the SKR over this period and develop an automatic method for finding low frequency extensions (LFE), where the SKR emission extends down to lower frequencies below the main band. LFEs have been shown to occur in response to reconnection at Saturn (Jackman et al, 2009) and their appearance in Earth's analogous Auroral Kilometric Radiation (AKR) has been shown to coincide with substorm onset (e.g. Morioka et al, 2007). Using a new catalogue of LFEs we discuss their correlation with known tail reconnection events and solar wind shocks (as inferred from the use of propagated solar wind models). We also look at their properties such as length and recurrence rate, as well as their relationship to the planetary periodicities.

  10. Influence of the foreshock on propagation of upstream discontinuities toward the magnetosphere

    Science.gov (United States)

    Urbar, Jaroslav; Nemecek, Zdenek; Safrankova, Jana; Prech, Lubomir; Jelinek, Karel

    Interplanetary shocks and other major solar wind discontinuities have been recognized as a very efficient source of geomagnetic disturbances and many studies have been devoted to the interaction of these discontinuities with both characteristic magnetospheric boundaries: the bow shock and magnetopause. However, an influence of the foreshock as a region with param-eters significantly different from those of the undisturbed solar wind was not discussed up to now. Non-stationarity of this region and interactions occurring there requires multi-spacecraft observations with a good spatial and temporal coverage. We use a large set of spacecraft orbiting in the solar wind (SOHO, Wind, ACE) and near the bow shock vicinity (Cluster II, Themis) and investigate what quantity controls the evolution and propagation of solar wind disturbances through the foreshock, bow shock and magnetosheath. Into the study, we included an inclination of the discontinuity normal from the Sun-Earth line that determines the propagation of the discontinuity along the bow shock surface as well as the direction of the motional electric field that can concentrate foreshock energetic particles at the discontinuity plane. These particles excite waves of large amplitudes that can modify not only the disturbance parameters but also mean values of parameters measured in an un-perturbed solar wind.

  11. System Science Tool for the Statistical Mapping of the Solar Wind - Magnetosheath - Magnetospheric System

    Science.gov (United States)

    Dimmock, A. P.; Nykyri, K.; Pulkkinen, T. I.; Osmane, A.

    2014-12-01

    The magnetosheath (MS) acts as a natural interface between the solar wind (SW) and magnetospheric (MSP) plasma and is therefore a key element in studying the driving of plasma properties in the inner MSP. However, understanding the behaviour of MS plasma properties due to the rapidly changing upstream conditions is no trivial matter and to date is not completely understood. Since the MS is situated between two very dynamic boundaries which respond directly to SW variations, their motion is significant to the order of several Earth radii. The combination of the spatial boundary variations and the non uniform nature of the SW not only make the compilation of statistical data problematic, but their interpretation is by no means straightforward. As a result, it is very difficult to build a complete picture of the global SW - MS - MSP system which accounts for upstream variations outside of the simulated environment. In the present study, we describe a statistical mapping methodology aimed at overcoming such difficulties. Our tool compiles statistical datasets for the MS and MSP in a normalised frame accounting for boundary motion, upstream SW variations and planetary aberration. We use THEMIS measurements for MS and MSP data whereas upstream estimates are provided by the OMNI database. Multiple datasets are compiled to produce statistical maps of the MS and MSP system and also to perform numerical analysis of the properties in each region. We use this methodology to study the presence of dawn/dusk asymmetries and their dependence on upstream conditions.

  12. Jupiter Magnetospheric Orbiter and Trojan Asteroid Explorer in EJSM

    Science.gov (United States)

    Sasaki, Sho; Fujimoto, Masaki; Yano, Hajime; Takashima, Takeshi; Kasaba, Yasumasa; Funase, Ryu; Tsuda, Yuichi; Kawaguchi, Junichiro; Kawakatsu, Yasuhiro; Mori, Osamu; Morimoto, Mutsuko; Yoshida, Fumi; Takato, Naruhisa

    The international mission to explore the Jovian system is planned as Europa Jupiter System Mission (EJSM) aiming at the launch in 2020. EJSM consists of (1) the Jupiter Europa Orbiter (JEO) by NASA, (2) the Jupiter Ganymede Orbiter (JGO) by ESA, and (3) the Jupiter Magnetospheric Orbiter (JMO) studied by JAXA (Japan Aerospace Exploration Agency). In February 2009, NASA and ESA decided to continue the study of EJSM as a candidate of the outer solar system mission. In JAXA, a mission plan combining Trojan asteroid explorer with JMO started. According to the mission plan, as the main spacecraft flies by Jupiter, it will deploy the JMO satellite around Jupiter. Then the main will target one (or two) Trojan asteroids. JMO is a spin-stabilized satellite which will have magnetometers, low-energy plasma spectrome-ters, medium energy particle detectors, energetic particle detectors, electric field / plasma wave instruments, an ENA imager, an EUV spectrometer, and a dust detector. Collaborating with plasma instruments on board JEO and JGO, JMO will investigate the fast-rotating huge mag-netosphere to clarify the energy procurement from the rotation of Jupiter to the magnetosphere and to clarify the interaction between the solar wind and the magnetosphere. JAXA started the study of a solar power sail for deep space explorations. In addition to the function of a solar sail (photon propulsion), the solar power sail system has very efficient ion engines where electric power is produced solar panels within the sail. Currently we are studying a mission to Jupiter and Trojan asteroids using a large (100m-scale) solar power sail that can transfer large payload as far as Jupiter. Trojan asteroids, which orbit around Jupiter's Lagrangian points, are primitive bodies with information of the early solar system as well as raw solid materials of Jovian system. Proposed instruments for the Trojan spacecraft are cameras, IR spectrometers, XRS, a laser altimeter, and a small surface rover

  13. Ionospheric Feedback Instability in the Coupling of Magnetosphere-Ionosphere

    Institute of Scientific and Technical Information of China (English)

    王旭宇; 曹晋滨

    2003-01-01

    The ionospheric feedback instability is discussed by using the conductivity argument. We give an exact quantitative description to show that the free energy for this instability comes from the reduction of the Joule dissipation produced by the pre-existing convection electric field through self-consistent changes in ionization and conducactive ionosphere is pumped into the magnetosphere, wlich is contrary to the usual case whereby energy carried electron E × B drift. The electron conductivity is controlled by the ion Perdersen conductivity rather than by the electrons Pedersen conductivity. We also provide a qualitative theoretical explanation to the intense aurora favoured by a lower ambient ionospheric conductivity in the ionospheric feedback instability.

  14. Galactic Cosmic Rays in the inner magnetosphere of Saturn

    Science.gov (United States)

    Kotova, Anna; Roussos, Elias; Krupp, Norbert; Dandouras, Iannis

    2015-04-01

    Existence of the Saturn innermost radiation belt in the tiny gap between planetary atmosphere and D-ring was first proposed in 2004 after the discovery of the significant fluxes of the energetic neutral atoms (ENA) coming from this area, what was measured by Ion and Neutron Camera on board of Cassini during the insertion orbit (1). One of the main sources of energetic charged particles for such inner radiation belt is the interaction of the Galactic Cosmic Rays (GCR) with the Saturn's atmosphere and rings, which due to CRAND process can produce the keV-MeV ions or electrons in the region. Using charged particles tracer developed in our group, we simulate the motion of the GCR using the backward tracing method and analyze the differences, arising from the usage of different magnetospheric models. The simulation was performed under assumptions of the dipole magnetic field model, then using more complex model with a magnetic equator offset and some other non-dipolar effects and later on using the Khurana model (2), which is based on the Cassini observations and for today is the most realistic model of the Saturn magnetosphere. We created maps of the GCR access to the Saturn atmosphere, analyzed changes of the minimum energy needed for GCR to reach the planet from different directions depending on the latitude and longitude and explained difference with analytically derived by Stormer theory values. Using those simulations and combine its results with Saturn atmospheric model and rings composition model, we estimate the production of secondaries resulting from the interaction of the GCR with atmosphere and from its penetration of the rings. This allows us to estimate the flux of energetic particles close to the planet, what will be useful for the preparation of the final "proximal" orbits of the Cassini spacecraft in 2017. For the validation of the results they are compared with the data from the Cassini insertion orbit. References: (1) S. M. Krimigis et al., "Dynamics

  15. Chaotic motion of dust particles in planetary magnetospheres

    Indian Academy of Sciences (India)

    Jia Xu; Xin Wu; Da-Zhu Ma

    2010-06-01

    We numerically investigate the motion of a charged particle in a planetary magnetosphere using several kinds of equatorial plane phase portraits determined by two dynamical parameters: the charge-to-mass ratio and the -component of the angular momentum. The dependence of chaos on any of the three factors including the two parameters and the energy is mainly discussed. It is found that increasing the energy or the absolute value of the ratio always causes the extent of chaos. However, chaos is weaker for larger

  16. A Comparative Examination of Plasmoid Structure and Dynamics at Mercury, Earth, Jupiter, and Saturn

    Science.gov (United States)

    Slavin, James A.

    2010-01-01

    The circulation of plasma and magnetic flux within planetary magnetospheres is governed by the solar wind-driven Dungey and planetary rotation-driven cycles. The Dungey cycle is responsible for all circulation at Mercury and Earth. Jupiter and Saturn's magnetospheres are dominated by the Vasyliunas cycle, but there is evidence for a small Dungey cycle contribution driven by the solar wind. Despite these fundamental differences, all well-observed magnetospheres eject relatively large parcels of the hot plasma, termed plasmoids, down their tails at high speeds. Plasmoids escape from the restraining force of the planetary magnetic field through reconnection in the equatorial current sheet separating the northern and southern hemispheres of the magnetosphere. The reconnection process gives the magnetic field threading plasmoids a helical or flux rope-type topology. In the Dungey cycle reconnection also provides the primary tailward force that accelerates plasmoids to high speeds as they move down the tail. We compare the available observations of plasmoids at Mercury, Earth, Jupiter, and Saturn for the purpose of determining the relative role of plasmoids and the reconnection process in the dynamics these planetary magnetic tails.

  17. Modeling the Young Sun's Solar Wind and its Interaction with Earth's Paleomagnetosphere

    CERN Document Server

    Sterenborg, M Glenn; Drake, Jeremy J; Gombosi, Tamas I; 10.1029/2010JA016036

    2011-01-01

    We present a focused parameter study of solar wind - magnetosphere interaction for the young Sun and Earth, $~3.5$ Ga ago, that relies on magnetohydrodynamic (MHD) simulations for both the solar wind and the magnetosphere. By simulating the quiescent young Sun and its wind we are able to propagate the MHD simulations up to Earth's magnetosphere and obtain a physically realistic solar forcing of it. We assess how sensitive the young solar wind is to changes in the coronal base density, sunspot placement and magnetic field strength, dipole magnetic field strength and the Sun's rotation period. From this analysis we obtain a range of plausible solar wind conditions the paleomagnetosphere may have been subject to. Scaling relationships from the literature suggest that a young Sun would have had a mass flux different from the present Sun. We evaluate how the mass flux changes with the aforementioned factors and determine the importance of this and several other key solar and magnetospheric variables with respect t...

  18. Sheared magnetospheric plasma flows and discrete auroral arcs: a quasi-static coupling model

    Directory of Open Access Journals (Sweden)

    M. M. Echim

    2007-02-01

    Full Text Available We consider sheared flows in magnetospheric boundary layers of tangential discontinuity type, forming a structure that is embedded in a large-scale convergent perpendicular electric field. We construct a kinetic model that couples the magnetospheric structure with the topside ionosphere. The contribution of magnetospheric electrons and ionospheric electrons and ions is taken into account into the current-voltage relationship derived for an electric potential monotonically decreasing with the altitude. The solution of the current continuity equation gives the distribution of the ionospheric potential consistent with the given magnetospheric electric potential. The model shows that a sheared magnetospheric flow generates current sheets corresponding to upward field-aligned currents, field-aligned potential drops and narrow bands of precipitating energy, as in discrete auroral arcs. Higher velocity magnetospheric sheared flows have the tendency to produce brighter and slightly broader arcs. An increase in arc luminosity is also associated with enhancements of magnetospheric plasma density, in which case the structures are narrower. Finally, the model predicts that an increase of the electron temperature of the magnetospheric flowing plasma corresponds to slightly wider arcs but does not modify their luminosity.

  19. Losses of Energetic Electrons in Earth's Outer Radiation Belt During Unusual Coronal Mass Ejections

    Science.gov (United States)

    Lugaz, Noé; Huang, Chia-Lin; Schwadron, Nathan; Spence, Harlan; Farrugia, Charles; Winslow, Reka

    2016-07-01

    The most extreme changes in solar wind parameters important for the coupling between the solar wind and the magnetosphere (dynamic pressure, dawn-to-dusk electric field, Alfven Mach number, plasma beta, …) occur during the passage at Earth of coronal mass ejections (CMEs). While the response of Earth's radiation belts to CMEs and CME-driven shocks has been investigated in great details, few studies have focused on what makes some CMEs and their shocks especially effective in driving losses of energetic electrons in the outer radiation belt. Here, we present specific examples of losses during the passage at Earth of a coronal mass ejection. In particular, we discuss the conditions which may result in the magnetopause to retreat earthward up to geosynchronous orbit, resulting in significant losses of energetic electrons due to magnetopause shadowing. We also present the result of a low-density magnetic ejecta which impacted Earth in January 2013. Combining interplanetary, magnetosheath, outer magnetosphere and radiation belt measurements by more than ten satellites, including the Van Allen Probes, THEMIS and Cluster, we show how a period of extremely low Mach number and dynamic pressure during the passage of the magnetic cloud resulted in dramatic losses in the outer radiation belt and a large-scale reorganization of the entire day-side magnetosphere.

  20. The X-Ray Polarization Signature of Quiescent Magnetars: Effect of Magnetospheric Scattering and Vacuum Polarization

    CERN Document Server

    Fernández, Rodrigo

    2011-01-01

    In the magnetar model, the quiescent non-thermal soft X-ray emission from Anomalous X-ray Pulsars and Soft-Gamma Repeaters is thought to arise from resonant comptonization of thermal photons by charges moving in a twisted magnetosphere. Robust inference of physical quantities from observations is difficult, because the process depends strongly on geometry and current understanding of the magnetosphere is not very deep. The polarization of soft X-ray photons is an independent source of information, and its magnetospheric imprint remains only partially explored. In this paper we calculate how resonant cyclotron scattering would modify the observed polarization signal relative to the surface emission, using a multidimensional Monte Carlo radiative transfer code that accounts for the gradual coupling of polarization eigenmodes as photons leave the magnetosphere. We employ a globally-twisted, self-similar, force-free magnetosphere with a power-law momentum distribution, assume a blackbody spectrum for the seed pho...

  1. Sulfur Earth

    Science.gov (United States)

    de Jong, B. H.

    2007-12-01

    Variations in surface tension affect the buoyancy of objects floating in a liquid. Thus an object floating in water will sink deeper in the presence of dishwater fluid. This is a very minor but measurable effect. It causes for instance ducks to drown in aqueous solutions with added surfactant. The surface tension of liquid iron is very strongly affected by the presence of sulfur which acts as a surfactant in this system varying between 1.9 and 0.4 N/m at 10 mass percent Sulfur (Lee & Morita (2002), This last value is inferred to be the maximum value for Sulfur inferred to be present in the liquid outer core. Venting of Sulfur from the liquid core manifests itself on the Earth surface by the 105 to 106 ton of sulfur vented into the atmosphere annually (Wedepohl, 1984). Inspection of surface Sulfur emission indicates that venting is non-homogeneously distributed over the Earth's surface. The implication of such large variation in surface tension in the liquid outer core are that at locally low Sulfur concentration, the liquid outer core does not wet the predominantly MgSiO3 matrix with which it is in contact. However at a local high in Sulfur, the liquid outer core wets this matrix which in the fluid state has a surface tension of 0.4 N/m (Bansal & Doremus, 1986), couples with it, and causes it to sink. This differential and diapiric movement is transmitted through the essentially brittle mantle (1024 Pa.s, Lambeck & Johnson, 1998; the maximum value for ice being about 1030 Pa.s at 0 K, in all likely hood representing an upper bound of viscosity for all materials) and manifests itself on the surface by the roughly 20 km differentiation, about 0.1 % of the total mantle thickness, between topographical heights and lows with concomitant lateral movement in the crust and upper mantle resulting in thin skin tectonics. The brittle nature of the medium though which this movement is transmitted suggests that the extremes in topography of the D" layer are similar in range to

  2. Modelling of the ring current in Saturn's magnetosphere

    Science.gov (United States)

    Giampieri, G.; Dougherty, M.

    2004-02-01

    . The existence of a ring current inside Saturn's magnetosphere was first suggested by smith80 and ness81,ness82, in order to explain various features in the magnetic field observations from the Pioneer 11 and Voyager 1 and 2 spacecraft. connerney83 formalized the equatorial current model, based on previous modelling work of Jupiter's current sheet and estimated its parameters from the two Voyager data sets. Here, we investigate the model further, by reconsidering the data from the two Voyager spacecraft, as well as including the Pioneer 11 flyby data set. First, we obtain, in closed form, an analytic expression for the magnetic field produced by the ring current. We then fit the model to the external field, that is the difference between the observed field and the internal magnetic field, considering all the available data. In general, through our global fit we obtain more accurate parameters, compared to previous models. We point out differences between the model's parameters for the three flybys, and also investigate possible deviations from the axial and planar symmetries assumed in the model. We conclude that an accurate modelling of the Saturnian disk current will require taking into account both of the temporal variations related to the condition of the magnetosphere, as well as non-axisymmetric contributions due to local time effects.

  3. Coherent whistler emissions in the magnetosphere – Cluster observations

    Directory of Open Access Journals (Sweden)

    I. Dandouras

    2007-02-01

    Full Text Available The STAFF-SC observations complemented by the data from other instruments on Cluster spacecraft were used to study the main properties of magnetospheric lion roars: sporadic bursts of whistler emissions at f~0.1–0.2fe where fe is the electron gyrofrequency. Magnetospheric lion roars are shown to be similar to the emissions in the magnetosheath while the conditions for their generation are much less favorable: the growth rate of the cyclotron temperature anisotropy instability is much smaller due to a smaller number of the resonant electrons. This implies a nonlinear mechanism of generation of the observed wave emissions. It is shown that the observed whistler turbulence, in reality, consists of many nearly monochromatic wave packets. It is suggested that these structures are nonlinear Gendrin's whistler solitary waves. Properties of these waves are widely discussed. Since the group velocity of Gendrin's waves is aligned with the magnetic field, these well guided wave packets can propagate through many magnetic "bottles" associated with mirror structures, without being trapped.

  4. Force-Free Magnetosphere of an Accreting Kerr Black Hole

    CERN Document Server

    Uzdensky, D A

    2005-01-01

    I consider a stationary axisymmetric force-free degenerate magnetosphere of a rotating Kerr black hole surrounded by a thin Keplerian infinitely-conducting accretion disk. I focus on the closed-field geometry with a direct magnetic coupling between the disk and the event horizon. I first present a simple physical argument that shows how the black hole's rotation limits the radial extent of the force-free link. I then confirm this result by solving numerically the general-relativistic force-free Grad--Shafranov equation in the magnetosphere, using the regularity condition at the inner light cylinder to determine the poloidal current. I indeed find that force-free solutions exist only when the magnetic link between the hole and the disk has a limited extent on the disk surface. I chart out the maximum allowable size of this magnetically-connected part of the disk as a function of the black hole spin. I also compute the angular momentum and energy transfer between the hole and the disk that takes place via the d...

  5. Particle acceleration in the vacuum gaps in black hole magnetospheres

    CERN Document Server

    Ptitsyna, K

    2015-01-01

    We consider particle acceleration in vacuum gaps in magnetospheres of black holes powered through Blandford-Znajek mechanism and embedded into radiatively-inefficient accretion flow (RIAF) environment. In such situation the gap height is limited by the onset of gamma-gamma pair production on the infrared photons originating from the RIAF. We numerically calculate acceleration and propagation of charged particles taking into account the detailed structure of electric and magnetic field in the gap and in the entire black hole magnetosphere, radiative energy losses and interactions of gamma rays produced by the propagated charged particles with the background radiation field of RIAF. We show that the presence of the vacuum gap has clear observational signatures. The spectra of emission from gaps embedded into a relatively high luminosity RIAF are dominated by the inverse Compton emission with a sharp, super-exponential cut-off in the very-high-energy gamma-ray band. The cut-off energy is determined by the proper...

  6. The Force-Free Magnetosphere of a Rotating Black Hole

    Science.gov (United States)

    Contopoulos, Ioannis; Kazanas, Demosthenes; Papadopoulos, Demetrios B.

    2013-01-01

    We revisit the Blandford-Znajek process and solve the fundamental equation that governs the structure of the steady-state force-free magnetosphere around a Kerr black hole. The solution depends on the distributions of the magnetic field angular velocity and the poloidal electric current. These are not arbitrary. They are determined self-consistently by requiring that magnetic field lines cross smoothly the two singular surfaces of the problem: the inner "light surface" located inside the ergosphere and the outer "light surface" which is the generalization of the pulsar light cylinder.We find the solution for the simplest possible magnetic field configuration, the split monopole, through a numerical iterative relaxation method analogous to the one that yields the structure of the steady-state axisymmetric force-free pulsar magnetosphere. We obtain the rate of electromagnetic extraction of energy and confirm the results of Blandford and Znajek and of previous time-dependent simulations. Furthermore, we discuss the physical applicability of magnetic field configurations that do not cross both "light surfaces."

  7. Superthermal electrons and Bernstein waves in Jupiter's inner magnetosphere

    Science.gov (United States)

    Barbosa, D. D.; Kurth, W. S.

    1980-01-01

    A theoretical model for generation of banded electrostatic emissions by low density, superthermal electrons is developed for application to Jupiter's magnetosphere. The model employs a power law form for the energy dependence and a loss cone pitch angle distribution of the superthermals to drive convective instability of Bernstein modes. A direct correspondence between spectral features of the 3/2 band and resonant superthermal electrons is found. The concept of a critical flux of resonant electrons able to provide 10 e-foldings of electric field amplification yields an explicit relation in terms of the background thermal electron pressure. This result is used to construct a theoretical/empirical model of thermal electron density and temperature from 6-20 Jupiter radii in the Jovian magnetosphere which suggests that the electron temperature is less than the ion temperature which is approximately equal to 10 times the electron temperature in this region. Finally, wave ray paths are computed for propagation in the magnetic equator and in the magnetic meridional plane of a dipole magnetic field. These ray paths suggest that intense wave activity is tightly confined to a small latitudinal extent, less than + or - approximately 4 deg, about the magnetic equator.

  8. The force-free twisted magnetosphere of a neutron star

    CERN Document Server

    Akgün, Taner; Pons, José A; Cerdá-Durán, Pablo

    2016-01-01

    We present a detailed analysis of the properties of twisted, force-free magnetospheres of non-rotating neutron stars, which are of interest in the modelling of magnetar properties and evolution. In our models the magnetic field smoothly matches to a current-free (vacuum) solution at some large external radius, and they are specifically built to avoid pathological surface currents at any of the interfaces. By exploring a large range of parameters, we find a few remarkable general trends. We find that the total dipolar moment can be increased by up to 40% with respect to a vacuum model with the same surface magnetic field, due to the contribution of magnetospheric currents to the global magnetic field. Thus, estimates of the surface magnetic field based on the large scale dipolar braking torque are slightly overestimating the surface value by the same amount. Consistently, there is a moderate increase in the total energy of the model with respect to the vacuum solution of up to 25%, which would be the available...

  9. Properties of Jupiter's magnetospheric turbulence observed by the Galileo spacecraft

    Science.gov (United States)

    Tao, Chihiro; Sahraoui, Fouad; Fontaine, Dominique; Patoul, Judith; Chust, Thomas; Kasahara, Satoshi; Retinò, Alessandro

    2015-04-01

    In collisionless plasmas, turbulence is thought to play an important role in mass transport and energy dissipation. Magnetic fluctuations in the Jovian magnetosphere are essential in a turbulent state. Previous studies of that turbulence have focused on the large scales using low time resolution of magnetic field data. Here we extend those studies to cover a wider range of scales by combining both low and high-time-resolution data of Galileo magnetometer. We use particle data from the plasma instrument and include energetic particle contributions to estimate the local plasma parameters. We obtain 11 power spectra of magnetic field in the frequency range of 10-4-1 Hz, which covers both magnetohydrodynamics and ion kinetic scales. The frequencies of the evidenced spectral breaks are found to be relatively well correlated with the characteristic scales of heavy ion. The spectral indices below and above the spectral breaks are found to be broad and cover the ranges of 0.6-1.9 and 1.7-2.5, respectively. An analysis of higher-order statistics shows an intermittent feature of the turbulence, found to be more prominent in the plasma sheet than in the lobe. Furthermore, a statistical survey of the power of the fluctuations using low-time-resolution data suggests a radially varying dawn-dusk asymmetry: the total power is larger in the duskside (dawnside) at 80 RJ), which would reflect flow shear and global magnetospheric activity.

  10. Plasma Transport at the Magnetospheric Flank Boundary. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Otto, Antonius

    2012-04-23

    Progress is highlighted in these areas: 1. Model of magnetic reconnection induced by three-dimensional Kelvin Helmholtz (KH) modes at the magnetospheric flank boundary; 2. Quantitative evaluation of mass transport from the magnetosheath onto closed geomagnetic field for northward IMF; 3. Comparison of mass transfer by cusp reconnection and Flank Kelvin Helmholtz modes; 4. Entropy constraint and plasma transport in the magnetotail - a new mechanism for current sheet thinning; 5. Test particle model for mass transport onto closed geomagnetic field for northward IMF; 6. Influence of density asymmetry and magnetic shear on (a) the linear and nonlinear growth of 3D Kelvin Helmholtz (KH) modes, and (b) three-dimensional KH mediated mass transport; 7. Examination of entropy and plasma transport in the magnetotail; 8. Entropy change and plasma transport by KH mediated reconnection - mixing and heating of plasma; 9. Entropy and plasma transport in the magnetotail - tail reconnection; and, 10. Wave coupling at the magnetospheric boundary and generation of kinetic Alfven waves.

  11. GK Per and EX Hya: Intermediate polars with small magnetospheres

    CERN Document Server

    Suleimanov, V; Ducci, L; Zhukov, G V; Werner, K

    2016-01-01

    Observed hard X-ray spectra of intermediate polars are determined mainly by the accretion flow velocity at the white dwarf surface, which is normally close to the free-fall velocity. This allows to estimate the white dwarf masses as the white dwarf mass-radius relation M-R and the expected free-fall velocities at the surface are well known. This method is widely used, however, derived white dwarf masses M can be systematically underestimated because the accretion flow is stopped at and re-accelerates from the magnetospheric boundary R_m, and therefore, its velocity at the surface will be lower than free-fall.To avoid this problem we computed a two-parameter set of model hard X-ray spectra, which allows to constrain a degenerate M - R_m dependence. On the other hand, previous works showed that power spectra of accreting X-ray pulsars and intermediate polars exhibit breaks at the frequencies corresponding to the Keplerian frequencies at the magnetospheric boundary. Therefore, the break frequency \

  12. Superthermal electrons and Bernstein waves in Jupiter's inner magnetosphere

    Science.gov (United States)

    Barbosa, D. D.; Kurth, W. S.

    1980-01-01

    A theoretical model for generation of banded electrostatic emissions by low density, superthermal electrons is developed for application to Jupiter's magnetosphere. The model employs a power law form for the energy dependence and a loss cone pitch angle distribution of the superthermals to drive convective instability of Bernstein modes. A direct correspondence between spectral features of the 3/2 band and resonant superthermal electrons is found. The concept of a critical flux of resonant electrons able to provide 10 e-foldings of electric field amplification yields an explicit relation in terms of the background thermal electron pressure. This result is used to construct a theoretical/empirical model of thermal electron density and temperature from 6-20 Jupiter radii in the Jovian magnetosphere which suggests that the electron temperature is less than the ion temperature which is approximately equal to 10 times the electron temperature in this region. Finally, wave ray paths are computed for propagation in the magnetic equator and in the magnetic meridional plane of a dipole magnetic field. These ray paths suggest that intense wave activity is tightly confined to a small latitudinal extent, less than + or - approximately 4 deg, about the magnetic equator.

  13. Magnetosheath control of solar wind-magnetosphere coupling efficiency

    Science.gov (United States)

    Pulkkinen, T. I.; Dimmock, A. P.; Lakka, A.; Osmane, A.; Kilpua, E.; Myllys, M.; Tanskanen, E. I.; Viljanen, A.

    2016-09-01

    We examine the role of the magnetosheath in solar wind-magnetosphere-ionosphere coupling using the Time History of Events and Macroscale Interactions during Substorms plasma and magnetic field observations in the magnetosheath together with OMNI solar wind data and auroral electrojet recordings from the International Monitor for Auroral Geomagnetic Effects (IMAGE) magnetometer chain. We demonstrate that the electric field and Poynting flux reaching the magnetopause are not linear functions of the electric field and Poynting flux observed in the solar wind: the electric field and Poynting flux at the magnetopause during higher driving conditions are lower than those predicted from a linear function. We also show that the Poynting flux normal to the magnetopause is linearly correlated with the directly driven part of the auroral electrojets in the ionosphere. This indicates that the energy entering the magnetosphere in the form of the Poynting flux is directly responsible for driving the electrojets. Furthermore, we argue that the polar cap potential saturation discussed in the literature is associated with the way solar wind plasma gets processed during the bow shock crossing and motion within the magnetosheath.

  14. The Evolution and Motion of Transient Events in The Solar Wind-Magnetosphere Interaction

    Science.gov (United States)

    Collado-Vega, Yaireska Marie

    Instabilities in the solar wind-magnetosphere interaction govern the entry of solar wind particles into the Earth's magnetosphere. These particles could ultimately be responsible for serious damage to our current technological systems. I use simulations and observations to investigate two kinds of instabilities that occur during unsteady interaction, magnetopause vortices and bursty reconnection resulting in flux transfer events (FTEs). For the magnetopause vortices analysis, magnetohydrodynamic (MHD) simulations were generated. Two cases were run, one for a nominal speed solar wind (360 km/s) and another for a high speed solar wind (700 km/s). Both cases had an abrupt change in the interplanetary magnetic field (IMF) orientation; 15 minutes being southward, -5 nT, and then turning northward, +5 nT, for two hours. No other parameter was changed in these runs. Using an IDL-based tool, I visualized the 2D and 3D nature of the vortices and compared my results with those obtained previously by Collado-Vega et al. (2007) who studied vortices using simulated MHD data initiated by real solar wind conditions. The characteristics of the vortices formed under dynamic solar wind conditions are consistent with vortices driven by surface waves on the magnetopause, like the Kelvin-Helmholtz (KH) instability. However, the majority of those developed under steady solar wind conditions suggest otherwise, especially the ones that developed on the dayside which are believed to be formed by the convection pattern created by high latitude reconnection. For the study of FTEs, I focus on Cluster satellite magnetopause encounters. The Cluster satellites orbit in a tetrahedral formation in near-polar orbits. I identified FTEs in Cluster observations from 2002 to 2003, and a total of 109 events were counted in the data set. A comparison of the analytical and global MHD simulation results indicates that most of the events form by component reconnection along a tilted subsolar reconnection

  15. Effects of the ring current and plasmasphere on ULF waves in the inner magnetosphere based on the GEMSIS-RC model

    Science.gov (United States)

    Seki, K.; Amano, T.; saito, S.; Miyoshi, Y.; Matsumoto, Y.; Umeda, T.; Miyashita, Y.; Ebihara, Y.

    2012-12-01

    Acceleration mechanisms of electrons to cause drastic variation of the Earth's outer radiation belt is one of outstanding issues of the geospace researches. While the radial diffusion of the electrons driven by ULF waves has been considered as one of the candidate mechanisms, efficiency of the mechanism under realistic ULF characteristics and distribution is far from understood. GEMSIS (Geospace Environment Modeling System for Integrated Studies) of STEL, Nagoya University, is the observation-based modeling project for understanding energy and mass transportation from the Sun to the Earth in the geospace environment. Aiming at understanding the dynamics of the inner magnetosphere during the geospace storms, the GEMSIS-Magnetosphere working team has developed a new physics-based model for the global dynamics of the ring current (GEMSIS-RC model). The GEMSIS-RC model is a self-consistent and kinetic numerical simulation code solving the five-dimensional collisionless drift-kinetic equation for the ring-current ions in the inner-magnetosphere coupled with Maxwell equations. We applied the GEMSIS-RC model for simulation of global distribution of ULF waves to test its capability of describing fast time scale phenomena like SCs and ULF waves. Two cases of background profile, i.e., cases without/with plasmapause in the simulation domain, are compared. The result shows that existence of plasmapause strengthens ULFs outside the plasmapause and widens the MLT region where the E_r (toroidal) component is excited from initially-given E_phi (poloidal) component. Comparison between runs with/without ring current ions show that the existence of hot ring current ions can deform and amplify the original sinusoidal waveforms. The deformation causes the energy cascade to higher frequency range (Pc4 and Pc3 ranges). The cascade is more pronounced in the high beta case. Combination with GEMSIS-RB model reproduced rapid radial transport by the drift resonance for ions with drift period

  16. The Origins of Plasmas in the Earth's Neighborhood (OPEN) program

    Science.gov (United States)

    Alexander, J. K.

    1984-01-01

    The nature and objectives of the OPEN program are overviewed. The Origins of Plasmas in the Earth's Neighborhood program was conceived in 1979 and proposed as a major new initiative to study the energetics of the earth's space environment by the end of the 1980s. The objectives of OPEN have been integrated into the Global Geospace Study (GGS) segment to the International Solar-Terrestrial Physics (ISTP) program now being planned jointly by NASA, ESA, and Japan. The goals will be to develop a global understanding of the flow of energy from the sun through the earth's space environment above the neutral atmosphere and to define the cause and effect relationships between the plasma physics processes that link different regions of this dynamic environment. A network of four spacecraft will be used, each one carrying an instrument complement to characterize the composition and behavior of the upstream solar wind, the high-altitude polar magnetosphere, the equatorial magnetosphere, and the comet-like geomagnetic tail. Multispectral cameras will also be carried to image polar auroras at ultraviolet, visible and X-ray wavelengths. Experimentalists and theorists on the international team will participate.

  17. Energetic (0.1- to 16-keV/e) magnetospheric ion composition at different levels of solar F10.7

    Science.gov (United States)

    Lennartsson, W.

    1989-01-01

    The effects of varying solar activity (as measured by the daily F10.7 index) on the composition of energetic magnetospheric ions H(+), He(2+), He(+), and O(+) were investigated using data obtained in the near-equatorial magnetosphere, between L = 3 and R = 23 earth radii, by the Plasma Composition Experiment on ISEE-1. The strongest effect was found in the number densities of the He(+) and the O(+) ions, which were found to increase by factors of about 3-5 and 5-10, respectively, over the full range of the F10.7. The peak density of the O(+) is about 20 times that of He(+) and is the highest at L of about 3-5. Both species showed a decreasing energy with increasing F10.7 at a radius less than 10 earth radii, from about 4-5 keV at low F10.7 to about 2-3 keV at high F10.7.

  18. Energetic (0.1- to 16-keV/e) magnetospheric ion composition at different levels of solar F10.7

    Science.gov (United States)

    Lennartsson, W.

    1989-04-01

    The effects of varying solar activity (as measured by the daily F10.7 index) on the composition of energetic magnetospheric ions H(+), He(2+), He(+), and O(+) were investigated using data obtained in the near-equatorial magnetosphere, between L = 3 and R = 23 earth radii, by the Plasma Composition Experiment on ISEE-1. The strongest effect was found in the number densities of the He(+) and the O(+) ions, which were found to increase by factors of about 3-5 and 5-10, respectively, over the full range of the F10.7. The peak density of the O(+) is about 20 times that of He(+) and is the highest at L of about 3-5. Both species showed a decreasing energy with increasing F10.7 at a radius less than 10 earth radii, from about 4-5 keV at low F10.7 to about 2-3 keV at high F10.7.

  19. North-South Asymmetries in Earth's Magnetic Field: Effects on High-Latitude Geospace

    CERN Document Server

    Laundal, K M; Milan, S E; Haaland, S E; Coxon, J; Pedatella, N M; Förster, M; Reistad, J P

    2016-01-01

    The solar-wind magnetosphere interaction primarily occurs at altitudes where the dipole component of Earth's magnetic field is dominating. The disturbances that are created in this interaction propagate along magnetic field lines and interact with the ionosphere-thermosphere system. At ionospheric altitudes, the Earth's field deviates significantly from a dipole. North-South asymmetries in the magnetic field imply that the magnetosphere ionosphere-thermosphere (M-I-T) coupling is different in the two hemispheres. In this paper we rev