A new whistler inversion method

Abstract

[1] A new whistler inversion method has been developed to obtain plasmaspheric electron densities and propagation paths deduced from measured whistler data. It is based on the exact Appleton-Hartree dispersion relation and recent experimental density distribution models, comprising the following components: a longitudinal whistler wave propagation model; an empirical electron density distributions model along the field lines based on Polar spacecraft data; and dipole and International Geomagnetic Reference Field approximation of the Earth's magnetic field. The new method predicts electron densities and propagation paths different from the earlier methods. The validation of the method is difficult owing to lack of in situ measurements. A multiple-path whistler group model was introduced in addition to the whistler inversion method assuming a simplified (logarithmic) dependence of equatorial electron density. A new, time-frequency domain transformation of multiple path groups led us to validate the components of the whistler inversion method, and it adds a major extension to the inversion method in the case of multiple-path whistler groups. Beside that, the method is capable of providing electron density profiles for the plasmasphere by the analysis of multiple-path propagation whistlers.

A statistical study over Europe of the relative locations of lightning and associated energetic burst of electrons from the radiation belt

“…The computed D 0 is identical for the four whistlers considered and equal to 50 s 1/2 . This value is fully compliant with the expected value for a L = 2.3 field line (Lichtenberger, 2009). Consequently, the characteristics of the observed whistlers are compatible with whistlers propagating along the magnetic field line and coming from the Southern Hemisphere.…”

“…For frequencies much smaller than the nose frequency, one can show that the approximation D(f ) = D 0 = constant is valid. At the time of the observations, DEMETER was on L = 2.3 field line which corresponds to a nose frequency greater than 30 kHz (Lichtenberger, 2009). Hereafter, we limit our study to the frequency range [0; 10] kHz, and accordingly we use a simplified Eckersley's law t = D 0 f −1/2 .…”

Propagation of whistler mode waves with a modulated frequency in the magnetosphere

“…These propagation times were determined to be 2.900 s and 2.675 s, respectively. There are a number of studies where plasma density in the magnetosphere is defined from ULF/VLF wave observations on the ground and on satellites [ Denton et al , 2006; Lichtenberger , 2009]. The simplest formula for the distribution of plasma density in the magnetosphere is given by Denton et al [2002]: n = n * ( L / r ) γ , where n * is the reference density in the equatorial plane on L dipole magnetic shell, and γ ≈ 1 inside the plasmasphere and γ ≈ 2.5 outside the plasmasphere.…”

Analysis of experimentally validated trans‐ionospheric attenuation estimates of VLF signals

“…However, using ground‐based data to quantitatively estimate in situ wave power [e.g., Golden et al ., ] requires knowledge of how efficiently the VLF waves penetrate downward from the magnetosphere through the ionosphere and into the Earth‐ionosphere waveguide. Similarly, understanding trans‐ionospheric propagation is an important aspect of using ground‐based or space‐based whistler measurements to remotely sense plasmaspheric electron densities [e.g., Carpenter , ; Carpenter et al ., ; Lichtenberger et al ., ; Lichtenberger , ].…”