HF modulated ionospheric currents

Abstract

[1] The HAARP HF facility is used to modulate the components of the auroral electrojet that flow in the D-region of the ionosphere, creating ELF/VLF radiation which is then measured at a receiver co-located with the HAARP HF antenna. An HF heating model is coupled to a full wave plasma interaction FDTD code to determine the ELF/VLF response of the ionospheric plasma to the modulated HF stimulation. The predicted FDTD fields on the ground are found to be in remarkable agreement with those measured at a receiver co-located with HAARP. The FDTD code also predicts an upwardly propagating whistler mode that is tightly bound to the magnetic field lines. Citation: Payne,

Radiation of ELF/VLF waves by harmonically varying currents into a stratified ionosphere with application to radiation by a modulated electrojet

“…The maximum change in conductivity occurs at 80 km and is equal to $80 nS m À1 (for both Pedersen and Hall components) [Payne et al, 2007]. This equals to relative changes of 22.5% for Pedersen and 3.5% for Hall components of the background conductivity.…”

“…The change in the electrojet currents is calculated by Payne et al [2007], for heating of the ionosphere by a sinusoidally modulated fully focused HF beam at 3.2 MHz and effective radiated power (ERP) of $24 MW. The x-axis is chosen in the eastward direction, and y-axis in the northward direction.…”

“…The altitude-dependent geomagnetic field is calculated using the IGRF model (http://modelweb.gsfc.nasa.gov/models/igrf.html) for the HAARP site and has components B 0 '{6 Â 10 À6 , 1.3 Â 10 À5 , À5.3 Â 10 À5 } T at the altitude of the D-region currents. The electron density and collision frequency profiles are assumed to be the same as in [Payne et al, 2007], with electron density profile extended to higher altitudes using the IRI model (http://modelweb.gsfc.nasa. gov/models/iri.html).…”

Low‐Frequency Waves in HF Heating of the Ionosphere

“…Previous results with ELF and ULF waves generated by modulating the polar electrojet (PEJ) [Rietveld et al, 1984[Rietveld et al, , 1987[Rietveld et al, , 1989Papadopoulos et al, 1990Papadopoulos et al, , 2005Moore, 2007;Payne et al, 2007] indicated that the wave amplitude had a maximum in the vicinity of the heater while monotonically decreasing with distance in a fashion consistent with guided wave propagation. In general, ICD driven waves have a minimum at the ground location defined by its intersection with the magnetic field line that passes through the heated volume.…”

FDTD analysis of HF heating effect on local ionosphere

“…A FDTD scheme was proposed by Payne [4] by coupling a HF heating model to a full wave plasma interaction FDTD code to study the ELF/VLF response of the ionospheric plasma to the modulated HF stimulation. The predicted FDTD fields on the ground are found to be in remarkable agreement with observation data.…”