AN ELECTROMAGNETIC MODEL OF THE REVERSAL OF THE GEOMAGNETIC FIELD

An electromagnetic model of the reversal of the geomagnetic field, based on Bullard-Parker's dynamo theory of the origin of the main geomagnetic field is described. It is shown that a reversal of the geomagnetic field may arise in that case when the toroidal field in the earth's interior turns itself into the opposite direction. The authors further show that if a large enough sudden fluctuation is given to the earth's rotation by whatever means, then the electromagnetic interaction between the core and the mantle may give rise to a reversal of the toroidal field and consequently a reversal of the geomagnetic field. The calculation indicated that the sudden fluctuation, which should be a decrease of the period of the Earth's rotation, is large enough only when its order of magnitude is greater than 10~2 ms. At the end of the work the time interval of each reversal is discussed. It is shown that each reversal can last 10~3—10~6 years.