Wave‐induced fluctuations in ionospheric electron content: A model indicating some observational biases

By assuming that a plane atmospheric wave acts on a plane-stratified F layer in the presence of a constant geomagnetic field, we derive an expression for the resulting perturbations in total columnar electron content as a function of wave and ionospheric-layer parameters and of the orientation of the column through the ionosphere. Although idealized, the model not only correctly predicts the order of magnitude of the observed perturbations but also makes visible much of the physics that determines the magnitude of wave-induced total-content fluctuations observed by using satellite transmissions through the ionosphere. Geomagnetic constraints on ion motion and a tendency for total-content fluctuation to be greatest when the ground-satellite path lies in a surface of constant atmospheric wave phase combine to introduce strong experimental biases that favor the observation of some waves and prevent the observation of others. The effects of these biases must be fully removed before total-content measurements can yield the statistical properties of atmospheric waves at ionospheric heights that may be useful in locating wave sources or in characterizing the dynamic state of the ionosphere.