Effect of equatorial electrojet intensity on its landmark distances.

Onwumechili, C. Agodi; Agu, C.E; Ozoemena, P. C.

doi:10.5636/jgg.41.461

Cited by 8 publications

(3 citation statements)

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“…The increase of the peak current density needed to decrease the half thickness, p km, by unit amount is greater for a small half thickness than for a large half thickness; about 2 A km-2 per km for a half thickness of about 5.4 km, but about 1 A kmP2 per km for a half thickness of about 6.04 km. In this case, actual in situ measurements have fully confirmed results from model fittings by Onwumechili & Ogbuehi (1967), Onwumechili & Agu (1981a) and Onwumechili et al (1989). However, this is the first time the resulting contraction of the electrojet has been demonstrated with a vertical dimension of the electrojet.…”

Section: Discussionsupporting

confidence: 72%

“…More recently, Onwumechili, Agu & Ozoemena (1989) showed that not only the width, but the entire electrojet current and its magnetic field contours contracted as the current intensity increased. It is important to investigate whether the thickness also contracts in the same way as the width when the intensity increases.…”

Section: The Relationship Between Current Intensity and Thickness Of mentioning

confidence: 99%

“…Onwumechili & Agu (1981a) substantiated the announcement by Onwumechili & Ogbuehi (1967) that the electrojet appeared to be narrower when it was more intense. More recently, Onwumechili, Agu & Ozoemena (1989) showed that not only the width, but the entire electrojet current and its magnetic field contours contracted as the current intensity increased. It is important to investigate whether the thickness also contracts in the same way as the width when the intensity increases.…”

Section: The Relationship Between Current Intensity and Thickness Of mentioning

confidence: 99%

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A study of rocket measurements of ionospheric currents-III. Ionospheric currents at the magnetic dip equator

Onwumechili

1992

Geophysical Journal International

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The 31 daytime rocket flight results within 0" or 2" dip latitude provide a good study of several issues leading to the following findings. In this zone, 60 per cent or more of ionospheric current systems have two layers. The lower layer has a peak density of 7 f 4 A k m -' at an altitude of 1 0 6 f 2 k m , a half thickness at half peak of 5.7 f 0.7 km and an altitude extent of 34 f 9 km. The upper layer has a peak density of about 1 A km-' at an altitude of 136 f 8 km and an altitude extent of 19 f 5 km. In some altitude structures, the single layer system is like a hybrid of the lower and the upper layers. The thickness of the equatorial electrojet decreases as its peak current density increases. From this and earlier findings, the electrojet contracts vertically and latitudinally as its peak current density increases. From the sample examined, there is not much difference between the intensities of the lower layers over India and Peru. However, the intensity of the upper layer over India is only about half of its intensity over Peru. The decrease of the electrojet current density in the afternoon is related more to the decrease in the east-west electrostatic field than to electron density or conductivity. A C electric field fluctuations caused by the cross-field instability have been observed in situ in the east-west direction only, in the frequency range of 5 to 120 Hz at altitudes of 85 to 105 km. It is shown that the geometrical and current density structures of the electrojet substantially influence the ratios of its internal to external magnetic field components, all of which initially increase in magnitude with dip distance. Within 0" to 2" dip latitude the ratios are 0.28 f 0.08 for the northward component X, -0.17 f 0.2 for the vertical component 2, and 0.23 f 0.02 for the total field F. A proposed simple measure of day-to-day variability shows promise.

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Section: Discussionsupporting

confidence: 72%

Section: The Relationship Between Current Intensity and Thickness Of mentioning

confidence: 99%