Studies of the E layer of the ionosphere I. Some relevant theoretical relationships

Abstract

In the course of an extended investigation of the E layer of the ionosphere, using verticalsounding data from many stations in different parts of the world, we have identified a number of ways in which E layer behaviour is not adequately explained in terms of current theories of ionized layer formation and variation. As the first part of that investigation, it was necessary to develop, in their most convenient form, certain quantitative expressions of the accepted theory, by which the experimental data could most readily be checked. A notable simplification in this connection is effected by the assumption that the maximum ionization density in the E layer assumes quasi-stationary values over the hours of daylight, for which alone experimental measurements are generally available. At the same time we have developed formulae expressing variations from the simple theory, based on what we consider to be possible alterations in the basic physical assumptions on which that theory was founded. Notable among these is the assumption that the E layer is influenced by vertical drift, behaving as a motor as well as a dynamo. In this Part I of the paper an account is given of such theoretical relationships. Part II will be devoted to our examination of the experimental data in the light of them, leading to the identification of certain extraneous influences, such as that of the S q overhead current system, which account in part for the anomalous E-layer behaviour.