Mechanisms for vertical separation of ions in sporadic-E layers

Wavelength dependence of the linear growth rate of the <I>E<sub>s</sub></I> layer instability

“…The results are derived within the framework of the linear growth rate of the E s layer instability, which by definition assumes an initial equilibrium configuration, and which has diminishing relevance when the background conditions are time-varying (Jones, 1989), and/or when evolution proceeds into the nonlinear regime. Although it is difficult to study these complicating effects in general, simulations can be used to study specific, judiciously chosen examples.…”

“…The linear growth rate, in general, applies to the growth of small perturbations about an equilibrium configuration. Because of possible time variation of the wind profile, there is some doubt about whether the equilibrium configuration assumed herein will ever be obtained (Jones, 1989). This fact colors the interpretation of the results, and one possible effect is discussed in Sect.…”

“…While some of the wind sheers used are very small, we have elected to present the results in Figure 3 organized by layer thickness out of the belief that it is the layer thickness, and not the wind shear, which is the fundamental determiner of the wavelength dependence. That is, in a realistic situation where the layer may not be in equilibrium, because instability growth occurs before equilibrium is achieved, or due to time dependence of the wind shear node altitude (Jones, 1989), or of the wind shear strength, or if there is some sort of anomalous diffusion process, etc., then the layer may be substantially thicker than the equilibrium value computed here. In such cases we expect the layer thickness, and not the instantaneous wind shear, to determine the wavelength dependence of the electrodynamical response.…”