Generation of coherent structures caused by ionospheric heating

The thermal parametric instability excited by powerful high-frequency (HF) radio waves in the F region of the ionosphere is investigated. The HF radio waves, propagating through this inhomogeneous, magnetized plasma, are transformed into large-amplitude electrostatic plasma waves, which in turn couple to pseudo-three-dimensional nonlinear low-frequency density disturbances. This scenario is described by a system of equations consisting of the nonlinear Schrodinger equation for the HF plasma wave envelope, and the nonlinear equations for the electron density and temperature fluctuations, which are reinforced by the nonlinear terms associated with the pondermotive force and the differential Joule heating of the electrons. The formation of three-dimensional density striation structures is analyzed.>