Abstract
Possibility of generation of large-scale sheared zonal flow and magnetic field by coupled under the typical ionospheric conditions short-scale planetary low-frequency waves is shown. Propagation of coupled internal-gravity-Alfven, Rossby-Khantadze, Rossby-Alfven-Khantadze and collision-less electron skin depth order drift-Alfven waves is revealed and investigated in detail. To describe the nonlinear interaction of such coupled waves with sheared zonal flow the corresponding nonlinear equations are deduced. The instability mechanism is based on the nonlinear parametric triple interaction of the finite amplitude short-scale planetary waves leading to the inverse energy cascade toward the longer wavelengths. It is shown that under such interaction intense sheared magnetic fields can be generated. Appropriate growth rates are discussed in detail.
Highlights
Numerous ground-based and satellite experiments justify permanent existence of zonal flows in different layers of the Earth’s atmosphere [1] [2]
In the given paper we review the possibility of generation of zonal flow and magnetic field by different coupled EM ULF waves in the weakly ionized Earth’s ionosphere
We show that the turbulence of such short-wavelength coupled waves may be unstable with the excitation of low-frequency and large-scale perturbation of the sheared zonal flow and sheared magnetic field
Summary
Numerous ground-based and satellite experiments justify permanent existence of zonal flows in different layers of the Earth’s atmosphere [1] [2]. Dynamical interaction of the sheared zonal flow with Rossby solitary vortical formations in the Earth’s atmosphere and ionosphere have been studied both analytically and numerically in [10] [11]. Such investigation shows that the zonal flow energy accumulates into the vortical structures leading to partitioning into several pieces composing a turbulent state. The excitation of zonal flow based on the triple planetary waves nonlinear parametric instability in the Earth’s ionospheric medium was widely investigated (see [14] [16]-[30] and references cited in). The corresponding driving forces are stipulated by the Reynolds and Maxwell’s stresses
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