Returning Flow of the Equatorial Electrojet Currents

Suzuki, Akira

doi:10.5636/jgg.25.249

Cited by 14 publications

(3 citation statements)

References 11 publications

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“…Peltiers & Hermance (1971) suggested a model of the equatorial electrojet with a Gaussian distribution of the current density. A model with a current ribbon of triangular intensity was introduced by Suzuki (1973). Recently, Agarwal & Weaver (1990) have computed the latitudinal variations of Δ H and Δ Z due to the equatorial electrojet with a Gaussian distribution of current intensity including the return current at off‐equator low latitudes.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic induction by the equatorial electrojet

Rastogi

2004

Geophysical Journal International

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S U M M A R YThis paper discusses the effects of currents induced inside the Earth at equatorial latitudes due to the currents in the ionosphere and the magnetosphere. The horizontal (H), vertical (Z) and eastward (Y ) components of the geomagnetic field at equatorial and low-latitude stations around the world are examined for effects due to solar daily (Sq) variations during normal as well as counter electrojet days, during solar flares, during storm sudden commencements (SSCs) and during the main phase of the magnetic storms. The Sq(Z) variations show an abnormally large positive peak at Indian electrojet stations and to a lesser extent at Koror in the forenoon hours when the temporal gradient of Sq(H) is largest. At Indian longitudes this abnormality is largest during equinoxes and December solstices.The nighttime bay disturbance, solar flares and SSC produce large impulses in the Z field at Indian stations and at Koror. The latitudinal extent of this abnormality is larger for events with shorter periods. The disturbance equatorial ring current produces a large decrease of Z field around the period in the middle of main phase of the storm when the Dst index is rapidly decreasing and not when Dst is most negative. A strong decrease in the Z field is observed at Yauca in the American sector during the main phase of the storm.The induction effects on the equatorial electrojet seem to be absent in central and eastern parts of South America, and in the African region. The significant induction effects observed in the recording of the Z field at Peredinia in Sri Lanka suggest a wide latitude of abnormal conductivity anomaly distribution in the Indo-Sri Lanka longitude sector. Our present understanding of the conductor being in Palk Strait between India and Sri Lanka needs to be revised on the basis of results described in this paper.The solar daily variations Sq of the eastward (Y ) and northward (X ) components of the geomagnetic field are primarily due to the overhead electric currents flowing in the E region of the ionosphere. The Sq variation of the vertical component (Z) of the field represents the spatial gradient of the horizontal current intensity. Chapman (1919) was the first to describe the average Sq variation of X , Y and Z fields based on the data from 21 observatories. The variations of X were northward at all stations but those of Y and Z were of opposite sign at stations north and south of the equator. A reversal of the daily variation of X was observed around 40 • N and 40 • S. The current system to describe these variations consists of two vortices around 40 • latitude between the dawn and dusk hours centred at 11:00 local time (LT).Plotting the latitudinal variations of the daily range of H at six lowlatitude observatories then existing round the world, Egedal (1947) found an abnormal intensification of the daily range of H over the dip equator. This phenomenon was ascribed by Chapman (1951) as due to an eastward band of electric current in the ionosphere, which he named the 'equatorial electrojet...

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Section: Introductionmentioning

confidence: 99%

Electromagnetic induction by the equatorial electrojet

Rastogi

2004

Geophysical Journal International

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“…However, the effect of the return currents on the ground magnetic variations is shown to be negligible in practice (SUZUKI, 1973).…”

Section: Model Of Equatorial Electrojetmentioning

confidence: 99%

A New Analysis of the Geomagnetic Sq Field

Suzuki

1973

J. geomagn. geoelec

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The geomagnetic solar quiet daily variation field, Sq, was analyzed by a new method and the result was compared with that of MATSUSHITA and MAEDA (1965). The new method is intended to avoid errors which occur in harmonic analysis due to the equatorial electrojet of narrow latitudinal width; the magnetic effect originating from equatorial electrojet currents is temporarily omitted until after the spherical harmonic analysis has been performed, and later the effect is added in. Compared with the results obtained by Matsushita and Maeda, it is found that: (1) Spherical harmonic coefficients for the Sq field generally become smaller. (2) Magnitude of the equivalent current systems external to the earth diminishes by 10-20 per cent. (3) The coefficients which are mainly responsible for the jet effect are as, ai0, bs, bio, a7, ail, etc.; they become considerably smaller. In many of these terms the amplitude ratio En /In of the external to the internal part also becomes smaller. (4) The amplitude ratios, En /In, for main terms become larger.

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“…and OZOEMENA,1989b. ) current distribution with reverse westward currents on the flanks of eastward current at the dip equator, originally derived from ground data (ONwuMECHILI,1965a(ONwuMECHILI, ,1966b, has been amply confirmed from satellite (ONWUMECHILI and OZOEMENA, 1989a, b), ground (SUZUKI, 1973;, physical model ANANDARAO and RAGHAVARAO, 1979;REDDY and DEVASIA,1981;SINGH and COLE, 1987), and rocket (MUSMANN and SELLER, 1978) data. ONWUMECIIILI and OGBUEHL (1967a) found from ground-based data that the half width w km of the EEJ decreased as its intensity increased.…”

Section: Empirical Models Used In the Analysis Of Equatorial Electrojmentioning

confidence: 99%

Study of the Return Current of the Equatorial Electrojet.

Onwumechili

1992

J. geomagn. geoelec

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Returning Flow of the Equatorial Electrojet Currents

Cited by 14 publications

References 11 publications

Electromagnetic induction by the equatorial electrojet

Electromagnetic induction by the equatorial electrojet

A New Analysis of the Geomagnetic Sq Field

Study of the Return Current of the Equatorial Electrojet.

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