Correction to “Earth potential over 4000 km between Hawaii and California” by L. J. Lanzerotti, C. H. Sayres, L. V. Medford, J. S. Kraus, and C. G. MacLennan

Lanzerotti, L. J.; Sayres, C. H.; Medford, L. V.; Kraus, J. S.; Maclennan, C. G.

doi:10.1029/92gl01328

Cited by 8 publications

(9 citation statements)

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“…Other similar events were also reported by Lanzerotti et al (1986Lanzerotti et al ( , 1987 and Friis-Christensen et aL (1988) using ground based magnetometer.…”

Section: Ionospheric Signatures Of Impulsively Magnetosphere Penetratingsupporting

confidence: 63%

“…The corresponding transient ionospheric convection is indeed poleward as observed by Goertz et al (1985) and Sandholt et al (1986). More recently Todd et al (1986) using radar data, Lanzerotti et al (1986Lanzerotti et al ( , 1987, Friis-Christensen et al (1988), andHeikkila et al (1989) using correlated ground based and satellite observations, have been able to show that the convection patterns induced into the 'boundary cusps' (as defined in Figure 13) by impulsively injected solar wind plasma irregularities, form westward propagating double vortex structures. The distribution of the convection velocities in these twin vortices is illustrated in Figure 14, taken from Friis-Christensen etal.…”

Section: Ionospheric Convection Patterns Resulting From Impulsive Penmentioning

confidence: 84%

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Non-steady-state solar wind-magnetosphere interaction

Lemaire

Roth

1991

Space Sci Rev

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Most of the theories proposed to explain the interaction between the solar wind and the geomagnetic field are stationary descriptions based on ideal MHD. In this review an alternative,,nonstationary description is discussed. According to this description, most of the plasma-field irregularities, i.e., plasmoids, detected in the solar wind can penetrate inside the geomagnetic field beyond what is considered to be the mean position of the magnetopause. It is the patchy solar wind plasma impinging on the geomagnetic field which imposes rapidly changing and non-uniform boundary conditions over the whole outer magnetospheric surface. This contrasts with the general belief that the observed field variations or 'events' arise sporadically near the magnetopause as the result of some plasma instability.A brief historical review is given to illustrate the evolution of the theoretical models proposed to explain the interaction of the solar wind with the magnetosphere. The emergence of the idea of 'impulsive penetration' of solar wind plasma irregularities into the magnetosphere is emphasized especially.A kinetic model of the unperturbed magnetopause is described. This model corresponds to a closed magnetosphere whose surface is a tangential discontinuity. This transition layer can sustain plasma jettings and can be traversed by impulsive penetrating plasmoids. This is against the general belief which considers tangential discontinuities as the worse case with respect to impulsive penetration and plasma jettings.The mean features of the theory of impulsive penetration are presented. Gusty penetration of solar wind plasmoids depends on their excess momentum density and on the orientation of the IMF. The motion of plasmoids across non-uniform magnetic field configurations (tangential discontinuities) is discussed theoretically. When the dielectric constant of the streaming plasma is large enough for collective polarization effects to become important, an electric field develops which permits cross-B motions of all charged particles as a whole plasma entity. It is re-emphasized that the value of the integrated Pedersen conductivity is a determining factor in eross-B plasma motion. On the other hand, interconnection of interplanetary magnetic field lines and geomagnetic field lines results from collective diamagnetic effects produced by magnetized plasmoids injected into the magnetosphere.Several consequences of this penetration mechanism are discussed. These are: the escape of energetic particles out of the magnetosphere, the eastward deflection of penetrating plasmoids, the magnetospheric and ionospheric convection patterns, the erosion of plasmoids, and the mass/momentum loading effects. Some significant experimental geophysical observations supporting the impulsive penetration model are also discussed.

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“…Other similar events were also reported by Lanzerotti et al (1986Lanzerotti et al ( , 1987 and Friis-Christensen et aL (1988) using ground based magnetometer.…”

Section: Ionospheric Signatures Of Impulsively Magnetosphere Penetratingsupporting

confidence: 63%

Section: Ionospheric Convection Patterns Resulting From Impulsive Penmentioning

confidence: 84%

Non-steady-state solar wind-magnetosphere interaction

Lemaire

Roth

1991

Space Sci Rev

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“…In practice, this is a challenging measurement to make (see, e.g. Lanzerotti et al (1992)). To circumvent some of these challenges, attempts at measuring Earth's global field have utilized transoceanic submarine cables, often out-of-service communications lines.…”

Section: Detection Of Toroidal Fieldsmentioning

confidence: 99%

On the genesis of the Earth's magnetism

2013

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Few areas of geophysics are today progressing as rapidly as basic geomagnetism, which seeks to understand the origin of the Earth's magnetism. Data about the present geomagnetic field pours in from orbiting satellites, and supplements the ever growing body of information about the field in the remote past, derived from the magnetism of rocks. The first of the three parts of this review summarizes the available geomagnetic data and makes significant inferences about the large scale structure of the geomagnetic field at the surface of the Earth's electrically conducting fluid core, within which the field originates. In it, we recognize the first major obstacle to progress: because of the Earth's mantle, only the broad, slowly varying features of the magnetic field within the core can be directly observed. The second (and main) part of the review commences with the geodynamo hypothesis: the geomagnetic field is induced by core flow as a self-excited dynamo. Its electrodynamics define 'kinematic dynamo theory'. Key processes involving the motion of magnetic field lines, their diffusion through the conducting fluid, and their reconnection are described in detail. Four kinematic models are presented that are basic to a later section on successful dynamo experiments. The fluid dynamics of the core is considered next, the fluid being driven into motion by buoyancy created by the cooling of the Earth from its primordial state. The resulting flow is strongly affected by the rotation of the Earth and by the Lorentz force, which alters fluid motion by the interaction of the electric current and magnetic field. A section on 'magnetohydrodynamic (MHD) dynamo theory' is devoted to this rotating magnetoconvection. Theoretical treatment of the MHD responsible for geomagnetism culminates with numerical solutions of its governing equations. These simulations help overcome the first major obstacle to progress, but quickly meet the second: the dynamics of Earth's core are too complex, and operate across time and length scales too broad to be captured by any single laboratory experiment, or resolved on present-day computers. The geophysical relevance of the experiments and simulations is therefore called into question. Speculation about what may happen when computational power is eventually able to resolve core dynamics is given considerable attention. The final part of the review is a postscript to the earlier sections. It reflects on the problems that geodynamo theory will have to solve in the future, particularly those that core turbulence presents.

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“…2 is the persistent modulation of the electron flux near the precessional drift frequency of the hot electrons. This type of behavior is suggestive of "drift echoes" which have been observed in satellite measurements of energetic particle transport [16].…”

Section: The Fourier Transform Of the Correlation Betweenmentioning

confidence: 61%

Observation of Chaotic Particle Transport Induced by Drift-Resonant Fluctuations in a Magnetic Dipole Field

Warren

Mauel

1995

Phys. Rev. Lett.

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The chaotic radial transport of energetic electrons trapped in a magnetic dipole field has been observed in a laboratory terrella. This transport is driven by multimode, drift-resonant plasma instabilities which are excited by the hot electron population.A transport simulation of energetic electrons interacting with a spectrum of electrostatic waves modeled on the measured fluctuations reproduces temporal features of the experimentally observed radial particle flux. PACS numbers: 52.25.Fi, 52.35.g, 94.20.Rr Charged particles trapped in a dipole magnetic field undergo collisionless radial transport when nonaxisymmetric fluctuations break the third adiabatic invariant alt, which is proportional to the unperturbed magnetic flux.For example, random variations in the solar wind intensity produce perturbations of the Earth's geomagnetic and convection electric fields which have a broad fluctuation spectrum dominated by low-order azimuthal components [1]. Quasilinear models of the resulting transport have been used to account for the radial profile of radiation belt particles measured with satellites [2,3]. The more general problem of chaotic radial transport driven by nonlinear wave-particle resonances in a dipole magnetic field has been examined by Chan, Chen, and White [4] using Hamiltonian methods. For spectra characterized by multiple discrete modes, the extent of the transport is restricted both in radius and in energy by the existence of specific wave-particle resonances, and the transport need not be quasilinear [5]. Recently, these techniques have been used to study the time evolution of proton phase space distributions in the Earth's magnetosphere induced by a given fluctuation spectrum [6].In this Letter, we report the first observations of waveinduced chaotic radial transport in a laboratory terrella, the Collisionless Terrella Experiment (CTX). These observations demonstrate a clear relationship between the wave spectrum and the induced resonant transport and provide the first laboratory test of Hamiltonian methods which can used to simulate magnetospheric transport. In addition, we observe wave-particle dynamics in an evolving nonlinear system which is a topic important to transport studies in other magnetically confined plasmas [7].In CTX, an energetic population of trapped electrons is produced using electron cyclotron resonance heating (ECRH) [8]. The trapped electrons excite quasiperiodic "bursts" of drift-resonant instabilities which we identify as the hot electron interchange mode [9,10]. We find that during these bursts the measured amplitudes, frequencies, and azimuthal mode numbers of the drift-resonant fluctuations meet the conditions required for global chaotic particle transport.During these times, significantly enhanced electron transport is observed with a gridded particle detector and this transport is strongly modulated at the drift frequency of the energetic electrons. At other times, when the instability wave spectrum does not satisfy the conditions for global chaos, no enhanced transp...

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Correction to “Earth potential over 4000 km between Hawaii and California” by L. J. Lanzerotti, C. H. Sayres, L. V. Medford, J. S. Kraus, and C. G. MacLennan

Cited by 8 publications

References 0 publications

Non-steady-state solar wind-magnetosphere interaction

Non-steady-state solar wind-magnetosphere interaction

On the genesis of the Earth's magnetism

Observation of Chaotic Particle Transport Induced by Drift-Resonant Fluctuations in a Magnetic Dipole Field

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