The Modulation of Ionospheric Alfvén Resonator on Heating HF Waves and the Doppler Effect

0　IntroductionIthasbeenwellknownthattheformationofIonosphericAlfv啨ｎＲｅｓｏｎａｔｏｒ(IAR)isforthebreakdownofgeometricop tics.ItscentralregionliesneartheheightofF regionelectrondensitypeak .Andatthetypicalheightof 30 0 0kmexiststhemaximumgradientofAlfv啨ｎｖｅｌｏｃｉｔｙ ,whichleadstothereflec tionofshearAlfv啨ｎｗａｖｅｓａｎｄｐｒｏｄｕｃｅｓｔｈｅｕｐｐｅｒｂｏｕｎｄａｒｙｏｆｔｈｅｒｅｓｏｎａｔｏｒ.Likewise,thelowerboundaryoftheresonatorformsneartheheightof 2 0 0 30 0km .Thus,she…

The modulation of ionospheric Alfvén resonator on heating HF waves and the Doppler effect

Abstract: The propagation of HF waves in IAR can produce many nonlinear effects, including the modulation effect of IAR on HF waves and the Doppler effect. To start with the dependence of the ionospheric electron temperature variaof the modulation effect and lucubrate possible reasons for the field can have an observable modulation effect on HF waves while its mechanism is quite different from that of Schumann resonant field on HF waves. The depth of modulation of IAR field, which directly inspires the formation of cross-spectrum between ULF waves and HF waves and results in spectral peaks at some gyro-frequencies of IAR. With respect to the Doppler effect during the propagation of HF waves in IAR, it is mainly caused by the motion of the high-speed flyer and the drifting electrons and the frequency shift from the phase variation of the reflected waves can be neglected when the frequency of HF incident wave is high enough.