The new electromagnetic ionosphere and how it differs from the old electrostatic one

Using a rigorous solution for the electromagnetic fluid equations, it is found that they do not predict the electric-field-mapping that is usually expected, and that even if they did, the ionospheric conductance would have a significantly smaller value. In fact, these equations predict wavelike effects on all transverse scales investigated, which are partially associated with short parallel wavelengths, and partially associated with the interaction of multiple modes. It is also found that the electrostatic-wave theory that is used, for example, to derive the spectrum of incoherent scatter, will likely produce unphysical results if extended to transverse scales longer than about one hundred meters. By way of comparison, the new solution is a linearized, causal, driven steady-state solution for the ionospheric conductance and electric field mapping, but it does not include the nonlinear elements of the time evolution, which are the purview of time-domain simulations. Also, although the signal is 3-dimensional, the background ionosphere is assumed horizontally uniform. Hence, the results are best understood as baseline, fundamental results that inform our thinking broadly.