Earth–ionosphere Cavity Resonances and the Propagation of Extremely Low Frequency Radio Waves

Observations of earth-ionosphere cavity resonances and their interpretation in terms of a two-layer ionosphere model

“…When a comparison is made with daytime profiles, for example that of Titheridge [1962], it can be seen that the thickness and conductivity of the " D region" of the model is a very fair representation of reality, but that the "E region" conductivity is considerably lower than might at first be expected. As mentioned in an earlier publication [Chapman and Jones, 1964b], there are reasons why this should be so. These reasons are connected with the effect of averaging the lower ionosphere profile over the whole earth and with the possible effect of the earth's magnetic field.…”

“…The resulting effective models are given in table 2 below. The observed effects of the P CA and the nuclear explosion have been discussed previously [Jones, 1963], and th e attenuation constant and phase velocity appropriate to these three models has been calculated on th e basis of the full mode theory for propagation und er a two layer ionosphere by Chapman and Jones [1964b]. Using t h e theory of Wait [1960], the results oJ this calculation ar e presented in figure 8, where they may be compared with the results of Harris and Tanner [1962] and some r ecent results of Galejs and Row [1964], the latter having included the effects of the earth's magnetic field.…”

Schumann resonances

“…The lowering of the resonance frequency followin g a nuclear explosion has been attributed by Chapman and Jones [1964a] in their two-layer ionosphere model solely to a decreasing conductivity of the E-region.…”

Low-Frequency Electromagnetic Oscillations of the Earth-Ionosphere Cavity

“…They are perhaps the easiest measurement to make, Benoit, 1962;Chapman, 1964;Lokken, 1961;Rycroft, 1963) The general character of the amplitute pattern has been explained in terms of localization of most of the lightning activity in the equatorial continental regions at local afternoon times. (Balser and Wagner, 1962).…”