Magnetospheric and Ionospheric Sources of Geomagnetic Field Variations


This study investigated the magnetospheric and ionospheric sources of geomagnetic field variation using the data set that consists of the hourly values of the geomagnetic element: horizontal intensity H, recorded at the geomagnetic observatory of the Department of physics, university of Ilorin, Ilorin (Long 4.670 and Lat. 8.50, dip 4.1 oS) Nigeria for the months of august, October and December in the year 2008. The study attributed the daytime variation to the ionospheric sources while various reasons were given to explain these night-time variations, which include convective drift currents in the magnetosphere and the asymmetric rings currents in the magnetospheric currents; this variation due to disturbances indicates possible non-ionospheric origin and a partial ring current in the night side magnetosphere. The mean monthly hourly variation showed seasonal variation with the Sq(H) maximizes in equinox with least variation in June solstice. Moreover, the mean ration of seasonal contributions of magnetospheric to ionospheric sources revealed that the E season has more contributions from both magnetospheric and ionospheric sources than other seasons with the least occurring during the J season.

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Elemo, E. and Rabiu, A. (2014) Magnetospheric and Ionospheric Sources of Geomagnetic Field Variations. Open Access Library Journal, 1, 1-8. doi: 10.4236/oalib.1101035.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Merrill, R.T., McElhinny, M.W. and McFadden, P.L. (1996) The Magnetic Field of the Earth: Paleomagnetism, the Core and the Deep Mantle. International Geophysics Series. Academic Press, San Diego, Vol. 63.
[2] Chapman, S. (1929) On the Theory of the Solar Diurnal Variation of the Earth’s Magnetism. Proceedings of the Royal Society Series A, 129, 369-386.
[3] Richmond, A.D., Matsushita, S. and Tarpley, J.D. (1976) On the Production Mechanism of Electric Currents and Fields in the Ionosphere. Journal of Geophysical Research, 81, 547-555.
[4] Campbell, W.H. (1996) Geomagnetic Storms, the Dst Ring Current Myth and Lognormal Distributions. Journal of Atmospheric and Solar-Terrestrial Physics, 58, 1171-1187.
[5] Campbell, W.H. (1973) The Field Levels Near Midnight at Low and Equatorial Geomagnetic Stations. Journal of Atmospheric and Solar-Terrestrial Physics, 35, 1127.
[6] Campbell, W.H. (1979) Occurrence of AE and Dst Geomagnetic Index Levels and the Selection of the Quietest Days in the Year. Journal of Geophysical Research, 84, 875.
[7] Rabiu, A.B. (1996) Night Time Geomagnetic Variations at Middle Atitudes Nigerian. Nigerian Journal of Physics, 8s, 35-37.
[8] Matveyenkov, I.T. (1983) Possible Effects of Distant field Sources on Sq Variations. Geomagnetism and Aeronomy, 23, 276-277.
[9] Rabiu, A.B. (2000) Geomagntic Field Variation at Middle Latitude. Ph.D. Thesis, University of Nigeria, Nsukka.
[10] Vestine E. (1947) The Geomagnetic Field, Its Description and Analysis. Carnegie Institute, Washington, 580.
[11] Eleman, F. (1973) The Geomagnetic Field in Cosmical Geophysics. In: Egeland, A., Holter, O. and Omholt, A., Eds., Chapter 3, Scandinavian University Books, Oslo, 45-62.
[12] Matsushita, S. (1969) Dynamo Currents, Winds, and Electric Fields. Radio Science, 4, 771-780.
[13] Onwumechili, A. (1960) Fluctuations in the Geomagnetic Horizontal Filed near the Magnetic Equator. Journal of Atmospheric and Terrestrial Physics, 17, 286-294.
[14] Emilia, D.A. and Last, B.J. (1977) A Study of Sq Variation at Addis Ababa. Journal of Atmospheric and Terrestrial Physics, 39, 375-381.
[15] Okeke, F.N., Onwumechili, C.A. and Rabiu, A.B. (1998) Day-to-Day Variability of Geomagnetic Hourly Amplitudes at Low Latitudes. Geophysical Journal International, 134, 484-500.
[16] Forbes, J.M. (1981) The Equatorial Electrojet. Reviews of Geophysics, 19, 469-504.
[17] Hutton, R. (1962) The Interpretation of Low Latitude Geomagnetic Daily Variations. Annales Geophysicae, 26, 927-933.
[18] Olsen, W.P. (1989) The Contribution of Magnetospheric Current to Sq. Pure and Applied Geophysics, 131, 447-462.

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