Note on conductivity models for the Earth

A method for studying conductivity models for the earth by integrating the equations of Lahiri and Price by finite difference methods is outlined. This method has been used to examine systematically the Lahiri-Price-Rikitake conductivity model. A number of independent forms for the Lahiri-Price-Rikitake model are obtained, and it is shown that an improvement in the experimental data (e.g., in the Dst analysis) is necessary before numerical methods can be applied with great success to the study of conductivity models and before a reduction in the number of independent forms of this model will be possible. The major problem is still one of reducing the degree of non-uniqueness to within manageable limits and is not one of obtaining a unique form for a given model. The significance of the different forms obtained for the Lahiri-Price-Rikitake model are discussed in relation to previous results. An extended-Lahiri-Price-Rikitake model is also introduced in order to study ocean effects. Its use leads to the same conclusions mentioned above.