Parametric Interaction of VLF and ELF Waves in the Ionosphere

V Sotnikov,E Mishin,N Gershenzon,A Sharma

doi:10.1109/iceaa52647.2021.9539823

V Sotnikov, E Mishin + Show 2 more

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https://doi.org/10.1109/iceaa52647.2021.9539823

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Abstract

Generation of Very Low Frequency (VLF) electromagnetic whistler waves due to the parametric interaction of quasi-electrostatic VLF waves known as Lower Oblique Resonance (LOR) waves and Extremely Low Frequency (ELF) waves are analyzed in the frame of two possible scenarios. In the first scenario, quasi-electrostatic LOR waves and ELF waves are excited by conventional loop and dipole antennas. In the second one, they are naturally excited by plasma instabilities in the plasmasphere boundary layer. We present the results of numerical simulations of nonlinear coupling between LOR and Fast Magnetosonic (MS) waves, which was suggested to explain the observations of VLF electromagnetic emissions at frequencies well above the lower hybrid resonance frequency in the Turbulent Plasmasphere Boundary Layer (TPBL). These emissions represent a distinctive subset of the substorm/storm-related VLF whistler activity contributing to the alteration of the outer radiation belt boundary. As the TPBL is interior to the plasma sheet inner boundary and thus devoid of substorm-injected kiloelectronvolt electrons, the standard whistler generation mechanism must be excluded. Numerical solution of the derived nonlinear equations show that parametric coupling of LOR and ELF waves creates VLF electromagnetic emissions with the spectral characteristics consistent with the observations.

Highlights

The generation of Very Low Frequency (VLF) sideband emissions due to parametric interaction of Lower Oblique Resonance (LOR) and Extremely Low Frequency (ELF) waves was first suggested in [1, 2] in an attempt to explain an experimental results observed in the ionosphere by the Aureol 3 satellite [3, 4] and during the CHARGE 2B ionospheric rocket experiment [5]
Nonlinear parametric interactions between quasi-electrostatic LOR and ELF waves was proposed as possible generation mechanisms of VLF whistler waves in the Turbulent Plasmosphere Boundary Layer (TPBL)
Obtained results show that nonlinear coalescence of the LOR and ELF waves leads to oblique electromagnetic VLF emissions at frequencies much greater than the LH resonance frequency, in agreement with the observations

Summary

Introduction

The generation of VLF sideband emissions due to parametric interaction of LOR and ELF waves was first suggested in [1, 2] in an attempt to explain an experimental results observed in the ionosphere by the Aureol 3 satellite [3, 4] and during the CHARGE 2B ionospheric rocket experiment [5]. Nonlinear parametric interactions between quasi-electrostatic LOR and ELF waves was proposed as possible generation mechanisms of VLF whistler waves in the Turbulent Plasmosphere Boundary Layer (TPBL). Excitation of these waves was analyzed through an assessment of observations from the Cluster spacecraft and Van Allen Probes [6]. Simulation results reveal generation of multiple sideband emissions around the pump VLF wave These simulation results strongly support analytical model presented in [1, 2] and used in [6, 7] to explain the observations of whistler waves in the plasmasphere boundary layer [11]

VLF waves in the ionosphere

Parametric excitation of VLF waves in the ionosphere

Excitation of whistler waves in a turbulent plasmapause boundary layer

Parametric excitation of whistler waves

Findings

Conclusion