Magnetic apex coordinates: A magnetic coordinate system for the ionospheric<i>F</i><sub>2</sub>layer

Vanzandt, T. E.; Clark, W. L.; Warnock, J. M.

doi:10.1029/ja077i013p02406

Cited by 98 publications

(64 citation statements)

References 5 publications

(1 reference statement)

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“…For further development of the electrodynamic equations, let us now focus on Magnetic Apex Coordinates (VanZandt et al, 1972). Their calculation uses a model of the geomagnetic main field to trace a field line to its apex, defined as its highest point above the Earth's surface, taking into account the slightly spheroidal shape of the Earth.…”

Section: Modified Apex Coordinatesmentioning

confidence: 99%

“…Walton and Bowhill, 1979). Three magnetic coordinate systems using realistic models of the Earth's main 191 field of internal origin that have been proposed for ionospheric work are: Magnetic Apex Coordinates (VanZandt et al, 1972); Coordinees de l'Anneau Equatorial or Corrected Geomagnetic Coordinates (Mayaud, 1960;Hakura, 1965;Gustafsson et al, 1992), upon which are based the PACE Geomagnetic Coordinates (Baker and Wing, 1989); and Constant B-Minimum Coordinates . These systems have constant values of magnetic latitude and longitude along field lines (apart from a possible sign switch in defining magnetic latitudes for the two magnetic hemispheres).…”

Section: Introductionmentioning

confidence: 99%

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Ionospheric Electrodynamics Using Magnetic Apex Coordinates.

Richmond

1995

J. geomagn. geoelec

616

744

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The equations of ionospheric electrodynamics are developed for a geomagnetic field of general configuration, with specific application to coordinate systems based on Magnetic Apex Coordinates. Two related coordinate systems are proposed: Modified Apex Coordinates, appropriate for calculations involving electric fields and magnetic-field-aligned currents; and Quasi-Dipole Coordinates, appropriate for calculations involving height-integrated ionospheric currents. Distortions of the geomagnetic field from a dipole cause modifications to the equations of electrodynamics, with distortion factors exceeding 50% at some geographical locations. Under the assumption of equipotential geomagnetic-field lines, it is shown how the field-line-integrated electrodynamic equations can be expressed in two dimensions in magnetic latitude and longitude, and how the height-integrated and field-aligned current densities can be calculated. Expressions are derived for the simplified calculation of magnetic perturbations above and below the ionosphere associated with the three-dimensional current system. It is shown how the base vectors for the Modified Apex coordinate system can be applied to map electric fields, plasma-drift velocities, magnetic perturbations, and Poynting fluxes along the geomagnetic field to other altitudes, automatically taking into account changes in magnitude and direction of these vector quantities along the field line. Similarly, it is shown how Quasi-Dipole coordinates are useful for expressing horizontal ionospheric currents, equivalent currents, and ground-level magnetic perturbations. A computer code is made available for efficient calculation of the various coordinates, base vectors, and related quantities described in this article.

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Section: Modified Apex Coordinatesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ionospheric Electrodynamics Using Magnetic Apex Coordinates.

Richmond

1995

J. geomagn. geoelec

616

744

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“…The Apex coordinate system is based on magnetic shells, where each magnetic shell has an apex of a given height above the Earth's surface. The latitude and longitude mappings in Apex coordinates are particularly suited for mapping the ionosphere, where the aurora happen to occur [VanZandt et al, 1972].…”

Section: Coordinate Systemsmentioning

confidence: 99%

Magnetospheric Model Performance during Conjugate Aurora

Longley

2016

Magnetosphere‐Ionosphere Coupling in the Solar System

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“…For the midlatitude case, with straight ®eld lines at dip angle I, the operator D reduces to the form derived by Ferraro (1945), with an eective coecient for vertical diusion, D sin 2 I. It later became feasible to adopt improved geometry, such as apex coordinates (Van Zandt et al, 1972), in the diusion equation, and to incorporate the International Geomagnetic Reference Field, as did Chan and Walker (1984a, b) for the East Asian sector, and later in the fully interactive thermosphereionosphere coupled model (Richmond et al, 1992).…”

Section: Causes Of Plasma Motionmentioning

confidence: 99%

The equatorial F-layer: progress and puzzles

Rishbeth

2000

Ann. Geophys.

182

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Abstract. This work reviews some aspects of the ionospheric F-layer in the vicinity of the geomagnetic equator. Starting with a historical introduction, brief summaries are given of the physics that makes the equatorial ionosphere so interesting, concentrating on the large-scale structure rather than the smaller-scale instability phenomena. Several individual topics are then discussed, including eclipse eects, the asymmetries of the`equatorial trough', variations with longitude, the semiannual variation, the eects of the global thermospheric circulation, and ®nally the equatorial neutral thermosphere, including`superrotation' and possible topographic in¯uences.

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Magnetic apex coordinates: A magnetic coordinate system for the ionosphericF₂layer

Cited by 98 publications

References 5 publications

Ionospheric Electrodynamics Using Magnetic Apex Coordinates.

Ionospheric Electrodynamics Using Magnetic Apex Coordinates.

Magnetospheric Model Performance during Conjugate Aurora

The equatorial F-layer: progress and puzzles

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Magnetic apex coordinates: A magnetic coordinate system for the ionosphericF2layer

Cited by 98 publications

References 5 publications

Ionospheric Electrodynamics Using Magnetic Apex Coordinates.

Ionospheric Electrodynamics Using Magnetic Apex Coordinates.

Magnetospheric Model Performance during Conjugate Aurora

The equatorial F-layer: progress and puzzles

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Magnetic apex coordinates: A magnetic coordinate system for the ionosphericF₂layer