TheSqvariation at geomagnetically conjugate areas

Wescott, E. M.; DeWitt, R. N.; Akasofu, S.‐I.

doi:10.1029/jz068i024p06377

Cited by 24 publications

(4 citation statements)

References 12 publications

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“…Although ionospheric winds will probably have a certain influence on the auroral electrojets, it seems less probable that these could be entirely driven by winds. The ionospheric dynamo theory for the auroral electrojets may also be criticized on other grounds [Wescott et al, 1963;Maeda, 1957].…”

Section: Ionospheric Dynamomentioning

confidence: 99%

A model of the auroral electrojets

Boström¹

1964

J. Geophys. Res.

495

248

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Certain observations indicate that the auroral electrojets are confined to the auroral arcs. A model of an arc is presented in which the height variation of the auroral ionization is taken into account and vertical currents are allowed to flow. The current flow in the arc is investigated, and the electric field or wind velocity field required to drive the currents is computed for two different cases: in one, the current flow between the auroral‐zone ionosphere and the outer magnetosphere is assumed to be limited and electric fields occur along the magnetic field lines in the magnetosphere; in the other, the conductivity along the field lines is assumed to be perfect. In the first case the electrojets are probably driven by a longitudinal electric field in the magnetosphere. In the second case the driving electric field must be a meridional field in order to explain the observations, and strong sheet currents must flow along the field lines that connect the auroral ionosphere to the outer magnetosphere.

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Section: Ionospheric Dynamomentioning

confidence: 99%

A model of the auroral electrojets

Boström¹

1964

J. Geophys. Res.

495

248

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“…(In contrast, the Sq current at lower latitudes is driven by vertical winds induced by solar heating.) In addition, the high-latitude magnetic activity has geomagnetically conjugate symmetry and local time features that would not be expected from a purely atmospheric current system [Wescott et al, 1963]. Bostr;Sm introduced the type I and type 2 current systems of Figure 1 and discussed Obviously, a nonuniform current system may be driven even in a uniformly conducting ionosphere by a nonuniform applied electric field.…”

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confidence: 99%

Observations of Birkeland currents at auroral latitudes

Anderson¹,

Vondrak²

1975

Reviews of Geophysics

103

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After many years of languishing interest, field‐aligned currents (Birkeland currents) are now regarded as an important link between the magnetosphere and the ionosphere. We describe techniques that are used to measure them and then discuss in some detail measurements that have been interpreted as indicating the presence of Birkeland currents. We conclude that measurements substantiate the theory of large‐scale flow from the magnetosphere to the polar caps in a dawn‐dusk direction with opposite flow equatorward of the auroral zone connecting to the Alfvén layer. Sheet current flow in premidnight discrete aurora seems experimentally established also, but its connection with auroral acceleration and with the larger‐scale flow is not yet understood. The currents flowing during a substorm are not yet fully defined either.

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“…However, o-o is very large everywhere in an above the ionosphere and any slight field set up along Bo should dissipate very swiftly (along Bo). This situation presents a new problem in the dynamo theory and ]Little is known as yet (FARLEY, 1959(FARLEY, , 1960MATStJSHIXA, 1960;WESCOTT et al, 1963). A recent study has shown that J~ =0 is approximately valid, though the total vertical current flowing from one hemisphere to the other is appreciable (MAEDA, K. and MURATA, 1965).…”

Section: -J~mentioning

confidence: 99%

Electrodynamics of the ionosphere

Maeda

Kato

1966

Space Sci Rev

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We review various important studies in the field of electrodynamics of the ionosphere. Four topics are presented; (1) conductivity, (2) wind and the dynamo theory, (3) drift and its effect on the ionosphere formation and (4) interaction between wind and electromagnetic field.We point out some important future problems. They are: (1) We need to consider in the dynamo theory of the geomagnetic daily variation the connection of the ionosphere of both hemispheres by lines of force of the geomagnetic field. (2) Non-periodic wind may be important for producing electric field. (3) Drift to cause interchange of ionization contained in tubes of the geomagnetic field lines, and diffusion of ionization in these tubes control dynamic lzehaviours of the F2 region. (4) Interaction between wind and electric current presents a new problem. (5) The ionosphere and the magnetosphere react to each other.

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TheS_qvariation at geomagnetically conjugate areas

Cited by 24 publications

References 12 publications

A model of the auroral electrojets

A model of the auroral electrojets

Observations of Birkeland currents at auroral latitudes

Electrodynamics of the ionosphere

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