Mechanism of the planetary Rossby wave energy amplification and transformation in the ionosphere with an inhomogeneous zonal smooth shear wind

Abstract

[1] The generation and further dynamics of planetary magnetized Rossby waves and inertia waves are investigated in the rotating dissipative ionosphere in the presence of a smooth inhomogeneous zonal wind (shear flow). Magnetized Rossby waves appear as a result of the interaction of the medium with the spatially inhomogeneous geomagnetic field and are an ionospheric manifestation of usual tropospheric Rossby waves. An effective linear mechanism responsible for the intensification and mutual transformation of Rossby and inertia waves is found. For shear flows, the operators of the linear problem are not self-adjoint, and therefore the eigenfunctions of the problem maybe nonorthogonal and can hardly be studied by the canonical modal approach. Hence it becomes necessary to use the so-called nonmodal mathematical analysis which has been actively developed in recent years. The nonmodal approach shows that the transformation of wave disturbances in shear flows is due to the nonorthogonality of eigenfunctions of the problem in the conditions of linear dynamics. Thus there arises a new degree of freedom and a new way for the evolution of disturbances in the medium. Using numerical modeling, we illustrate the peculiar features of the interaction of waves with the background flow as well as the mutual transformation of wave disturbances in the D, E, and F regions of the ionosphere. It is established that the presence of a geomagnetic field, Hall and Pedersen currents in the ionospheric medium, improves the interaction and mutual energy exchange between waves and a shear flow.

Self-organization of ULF electromagnetic wave structures in the shear flow driven dissipative ionosphere

“…Depending on the type of velocity profile of the zonal shear flow (wind), the generated nonlinear long-lived vortex structures maybe represent monopole solitary anticyclone or cyclone, the cyclone -anticyclone pair, connected in a certain manner and/or the pure dipole cyclone -anticyclone structure of equal intensity, and/or the vortex street, or the vortex chains, rotating in the opposite direction and moving along the latitudinal circles (along the parallels) against a background of the mean zonal wind (see also Jovanovich et al, 2002;Aburjania et al, 2003Aburjania et al, , 2006Aburjania et al, , 2007. The nonlinear large-scale vortices generate the stronger pulses of the geomagnetic field than the corresponding linear waves.…”

“…T is the value of geomagnetic field strength in the pole and we suppose that geomagnetic colatitude θ coincides with a geographical colatitude θ . In the ionosphere the large-scale motions are quasihorizontal (two-dimensional) (Aburjania et al, 2002(Aburjania et al, , 2003(Aburjania et al, , 2006 and hydrodynamic velocity of the particles…”

“…4) feeds the medium with external source of energy for generation of the wave structures (development of the shear flow instability). The shear flows can become unstable transiently until the condition of the strong relationship between the shear flows and wave perturbations is satisfied (Chagelishvili et al, 1996;Aburjania et al, 2006), e. i. the perturbation falls into amplification region in the wave number space. Leaving this region, e. i. when the perturbation passes to the damping region in the wave vector space, it returns an energy to the shear flow and so on (if the nonlinear processes and selforganization of the vortex structure will not develop before) (Aburjania et al, 2006).…”

Three-Dimensional Magnetogradient Waves in the Upper Atmosphere

“…These waves in [8,9] were called magnetogradient waves of Khantadze. In the above-stated papers [2][3][4][5][6][7] classification of magnetogradient planetary waves (fast and slow), hydrodynamic end electromagnetic nature of these waves and the anisotropic nature of their propagation caused by curvature of lines of force of the geomagnetic field along the Earth parallels was for the first time given. Assessment of parameters of the considered waves, and also linear and nonlinear theories of magnetogradient waves, is given in [10][11][12][13][14]. Experimentally these waves were recorded in [8,15,16].…”