Adiabatic motion of outer-zone particles in a model of the geoelectric and geomagnetic fields

Taylor, Harold E.

doi:10.1029/jz071i021p05135

Cited by 27 publications

(9 citation statements)

References 26 publications

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“…An example of the effect on particle drift paths, and hence on auroral precipitation patterns, of steady magnetospheric convection has been developed by detailed calculations in papers by Taylor and Hones [1965], Taylor [1966], and Hones [1968•]. Although this approach provides useful qualitative insight into the importance of convection in auroral phenomena, and indeed yields some predictions, i[ has been criticized by Axford [1969] and Williams [1970] as being extremely sensitive to the exac[ electric-field model selected and, in addition, as presenting an oversimplified picture of a very dynamic convection process.…”

Section: Direct Observaqons At High Latitudes Both At High Altitudesmentioning

confidence: 99%

The patterns and sources of high‐latitude particle precipitation

Paulikas¹

1971

Reviews of Geophysics

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We survey, in this paper, the properties of the zones of particle precipitation at high latitudes. We consider the average properties of particle influx from the outer magnetosphere as determined by satellite and rocket observations, as well as ground‐based techniques. The point of view of this paper is to try to associate source regions, and, if possible, precipitation mechanisms with each of the families of precipitating particles that collectively form the auroral zone. The precipitation patterns for both electrons and protons exhibit a diurnal variation. The several zones of particle precipitation can be placed in relationship to each other. The zone of electron precipitation is best described as consisting of a region at low latitudes (60° ⪝ Λ ⪝ 70° near local midnight) where electrons with characteristic energies of tens of kev precipitate; this region merges and overlaps at the higher latitudes with another region (70° ⪝ Λ ⪝ 80° near local midnight) characterized by precipitating electrons of ≈0.5 kev. The limited data available indicate that the zone of proton precipitation spatially overlaps the zone of electron precipitation. For example, the peak of precipitation of > 4‐kev protons near local midnight is found between Λ = 65° and Λ = 70°. Near local noon a separate region of very soft proton precipitation is found in the vicinity of Λ ≈ 80°, in addition to a region of proton influx at lower latitudes. We consider the plasma sheet, the extraterrestrial ring current, the polar cusp, and the outer radiation belt as source regions of precipitating particles. Brief surveys of the precipitation of helium ions and of possible means of artificially inducing particle precipitation are also included.

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Section: Direct Observaqons At High Latitudes Both At High Altitudesmentioning

confidence: 99%

The patterns and sources of high‐latitude particle precipitation

Paulikas¹

1971

Reviews of Geophysics

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“…In other models, the parameters have no physical meaning, and we may call them 'mathematical. ' There are two types of magnetospheric models currently used in the literature: the 'physical' model of Mead and Williams [Mead, 1964;Williams and Mead, 1965] and the 'mathematical' image-dipole model [Hones, 1963;Taylor and Hones, 1965;Taylor, 1966]. The Mead-Williams (M-W) model is an expansion in spherical harmonics for external sources, similar in principle to internal-source field models.…”

Section: Experimental Verifications Of Magnetospheric Modelsmentioning

confidence: 99%

Quantitative models of the magnetosphere

Roederer¹

1969

Reviews of Geophysics

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A clear understanding of the basic forms of motion of charged particles in the magnetic and electric fields of the outer magnetosphere is an essential ingredient to the study of the earth's radiation belts and plasma. To achieve this, one must work with a reliable quantitative model of the magnetospheric field. The main purpose of any such model is to provide a mathematical description of the field that is reasonably accurate within a given spatial and temporal domain and that can be used to analyze in a quantitative way any proce• influenced or governed by this field in the corresponding domain. In this review, magnetic field models of the magnetosphere are critically examined and their fit to in-situ field measurements is discussed. Spe.cial attention is paid to the analysis of typical long-term time variations of the field configuration and the matching changes in model parameters. Implications for adiabatic particle motion, such as she11 geometry, regions of pseudo-trapping, and adiabatic effects of slow time variations of the field, are analyzed. Why do we want a quantitative model of the magnetosphere? How do we test the validity of a model? 3. How can we build long-term time variations into a model? 4. What needs to be done in the near future to improve the quantitative description of the magnetospheric field?Each of these questions will be discussed, in turn, in the four sections that follow. THE NEED FOR A MAGNETOSPHERIC MODELThe broad purpose of a magnetospheric model is to provide a mathematical description of the field (analytical or numerical) that is reasonably accurate within a given limited spatial and temporal domain and that can be used to 77 78 JUAN G. 1tOEDERER study in a quantitative way any physical process influenced or governed by this field. This means that whenever one refers to a given model, one has to specify its spatial domain of validity, the time interval to which it is to be applied, and the type of physical processes for whose study the model is intended.Our discussion will be restricted to the magnetospheric domain between, say, 4 and 15 R• from the center of the earth, which we (arbitrarily) define as the 'outer magnetosphere.' Beyond about 4 R• only the dipole terms of the int. ernal-field expansion survive, making its representation easy. Beyond about 15 R• we essentially have 'pure tail field,' a subject discussed in another review paper at this symposium [Ness, 1969]. Only quiet or slightly disturbed intervals of time will be considered. In other words, only slow time variations of the field configuration will be envisaged.Among the physical processes whose description requires a magnetospheric model, six are described in the following paragraphs a. Trapped-particle motion. There has been a tendency in the past to use a dipole field configuration as a first approximation in the treatment of particle motion. However, the azimuthal asymmetry of the magnetic field in the outer magnetosphere does introduce quite important differences in the particles' kinematic behavior, which ...

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“…The first approach was applied in many models including the first ones by WILLIAMS and MEAD (1965), TAYLOR and HONES (1966), ANTONOVA and SHABANSKY (1968), TSYGANENKO (1976TSYGANENKO ( , 1981. The principal deficiency of the first models was their inability to incorporate the effects of the dipole-tilt-related flexing of the sheet and to simulate the realistic geometry of the electric current flow lines; one more troublesome point was the singular behaviour of BT at the edges of the sheet.…”

Section: The Tail Current Fieldmentioning

confidence: 99%

Models of Magnetospheric Magnetic Field

Tsyganenko

1991

J. geomagn. geoelec

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Configuration of the magnetic field in the near-Earth space is known to be the most important factor determining links between the magnetosphere and ionosphere such as thermal plasma flows, electric field mapping, solar particle trajectories, low-frequency electromagnetic wave and heat propagation. One of methods for constructing the magnetospheric magnetic field models implies using large amounts of spacecraft data which are sorted out in intervals of geomagnetic disturbance indices and/or solar wind characteristics. The obtained datasets are then used for least squares fitting parameters of functions which approximate contributions to the total field coming from the main magnetospheric B sources. This opens a possibility for studying the average dependence of geometry and intensity of the magnetospheric electric current systems on the ground activity level as well as on the solar wind state. Recent progress and future prospects in this area is reviewed and discussed.

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Adiabatic motion of outer-zone particles in a model of the geoelectric and geomagnetic fields

Cited by 27 publications

References 26 publications

The patterns and sources of high‐latitude particle precipitation

The patterns and sources of high‐latitude particle precipitation

Quantitative models of the magnetosphere

Models of Magnetospheric Magnetic Field

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