The effects of ions on low frequency and very low frequency propagation in an abnormally ionized atmosphere

Abstract

The purpose of this letter is to point out the important role of ions in affecting LF and VLF sky wave transmission during periods of abnormal ionization of the region below the normal D layer such as occurs in a polar cap proton event. The approach is quite simplified and approximate; however, it is adequate to demonstrate the considerable—and in some cases dominant—role of the ions and their importance in interpretation of VLF and LF sky wave propagation effects (phase and amplitude) during periods of abnormal ionization well below the normal D layer. As a consequence of the effect of ions, deductions about the chemistry and ionization reactions in this region that are based on interpreting the propagation effects as due to electrons alone are subject to serious, if not gross, error.