Whistler Waves Above the Lower Hybrid Frequency in the Ionosphere and Their Counterparts in the Magnetosphere

In this study, we report the statistical properties of whistler mode lower hybrid (LH) emissions in the ionosphere, which have structureless spectra with a lower frequency boundary that matches the variation of the local lower hybrid resonance frequency f(LHR). A potential source for the LH emissions is identified as the high-frequency plasmaspheric hiss (HFPH) in the magnetosphere. We use Detection of Electromagnetic Emissions Transmitted from Earthquake Regions and Van Allen Probes data to perform a statistical study of the wave power distribution of the LH emissions and HFPH. Both LH and HFPH emissions show a similar frequency range, a similar invariant magnetic latitude range, and have similar trends in magnetic local time (stronger wave intensity on the dayside) and in the auroral electrojet (AE) index (stronger wave intensity for higher AE condition). A ray tracing simulation is also performed to demonstrate the propagation of HFPH waves from the magnetosphere into the ionosphere as LH waves.