Letter | Published:

Formation of Equatorial Electrojet Current Layers

Naturevolume 214pages375376 (1967) | Download Citation



MEASUREMENTS of equatorial electrojet current by rockets have produced evidence for two current layers. The first electrojet current layer is prominent and appears at a height about 100 km and the second layer is less prominent and appears at heights of 120–150 km as shown in Fig. 1. The formation of the first electrojet current layer is fairly well understood whereas the formation of the second electrojet current layer is neither theoretically established nor its height of appearance experimentally ascertained. Zmuda1 assumed a constant conductivity and a parabolic variation with height in the horizontal electric field to explain the magnitude and height of appearance of the second electrojet current layer. But his assumptions are quite unrealistic2. Cahill3 recorded two equally prominent electrojet current layers (Fig. 1) and argued that one of the two electrojet current peaks results from the presence of sporadic E at that height. Whitehead2 considered Cahill's data of 1959 and pointed out the anomaly in interpreting the equal amount of currents in the upper and lower electrojet current layers. In recent flights4, however, it has been found that the first current peak is considerably stronger (Fig. 1) compared with the simultaneous second electrojet current peak. In the present communication we have invoked partial Hall current inhibition to explain the observed characteristics of the electrojet current layers.

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  1. 1

    Zmuda, A. J., J. Geophys. Res., 65, 2247 (1960).

  2. 2

    Whitehead, J. D., Planet Space Sci., 14, 519 (1966).

  3. 3

    Cahill, jun., L. J., J. Geophys. Res., 64, 489 (1959).

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    Maynard, N. C., and Cahill, jun., L. J., J. Geophys. Res., 70, 5923 (1965).

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    Kato, S., Planet Space Sci., 11, 823 (1963).

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    Karplus, R., Francis, W. E., and Dragt, A. J., Planet Space Sci., 9, 771 (1962).

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    Maeda, K., Tsuda, T., and Maeda, H., Rep. Ionos. Space Res. (Japan), 17, 147 (1963).

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  1. Engineering College, Department of Physics, Banaras Hindu University, India

    • R. N. SINGH
    •  & K. D. MISRA


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