Wavelength dependence of the <I>E<sub>s</sub></I> layer instability, and of coupling to the F layer, in the nonlinear regime

Abstract

Abstract. The E s layer instability has been suggested as a participant in the creation of frontal structures observed in both the E s and F layers of the nighttime midlatitude ionosphere, in spite of the fact that the spatial scales of the frontal structures are very different in the two layers. The linear growth rate of the instability has a maxima in the vicinity of the wavelength observed for the E s layer structures (short wavelengths). However, the maxima is non-distinct, and simulations have shown that the instability is extremely nonlinear. Therefore, to understand the wavelength dependence of the E s layer instability it is necessary to factor in nonlinear behavior. Simulations have shown that the instability is active at the wavelengths observed in the F layer, and revealed that the E s layer behavior at these long wavelengths is so nonlinear that the common, highly localized E s layer observation techniques would likely miss the signature, which is highly visible in the F layer. However, there is currently no explanation for why long wavelengths so clearly dominate short (or intermediate) wavelengths in the F layer observations, and this is a weakness in arguments that the E s layer instability participates in the creation of F-region frontal structures. Herein we remove this weakness by showing that longer wavelengths grow to larger amplitudes before eventual nonlinear saturation, and couple more effectively to the F-region.

Does a localized plasma disturbance in the ionosphere evolve to electrostatic equilibrium? Evidence to the contrary

“…It seems that many previous results must be affected by many authors. This author intends to begin by reconsidering E-F coupling effects in a number of his previous works Cosgrove, 2007aCosgrove, , 2007bCosgrove, , 2008and Cosgrove, 2013] and by reanalyzing the IFI. Also, we intend to perform ionospheric…”

Scale dependence and frontal formation of nighttime medium‐scale traveling ionospheric disturbances

“…The short wavelength cutoff occurs at around 20 km because the wavelength becomes comparable to the layer thickness, and the growth rate gradually decreases at longer wavelengths mode due to the F layer loading effect. Cosgrove [] studied the E‐F coupled instability by two‐dimensional simulation and showed that longer wavelengths grew to larger amplitude because of a longer interaction time between the two regions. Although several aspects given by the above‐mentioned studies are consistent with the observations, they could not quantitatively explain the preferable wavelength of MSTIDs.…”