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1. Survey of Whistler‐Mode Wave Amplitudes and Frequency Spectra in Jupiter's Magnetosphere

   https://doi.org/10.1029/2024GL111882  

   Ma, Q.; Li, W.; Zhang, X‐J; Kang, N.; Bortnik, J.; Qin, M.; Shen, X‐C; Meyer‐Reed, C_J; Artemyev, A_V; Kurth, W_S; et al (November 2024, Geophysical Research Letters)

   Abstract We present statistical distributions of whistler‐mode chorus and hiss waves at frequencies ranging from the local proton gyrofrequency to the equatorial electron gyrofrequency (f_ce,eq) in Jupiter's magnetosphere based on Juno measurements. The chorus wave power spectral densities usually follow thef_ce,eqvariation with major wave power concentrated in the 0.05f_ce,eq–f_ce,eqfrequency range. The hiss wave frequencies are less dependent onf_ce,eqvariation than chorus with major power concentrated below 0.05f_ce,eq, showing a separation from chorus atM < 10. Our survey indicates that chorus waves are mainly observed at 5.5 < M < 13 from the magnetic equator to 20° latitude, consistent with local wave generation near the equator and damping effects. The hiss wave powers extend to 50° latitude, suggesting longer wave propagation paths without attenuation. Our survey also includes the whistler‐mode waves at high latitudes which may originate from the Io footprint, auroral hiss, or propagating hiss waves reflected to highMshells. 

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2. A 3‐D FDTD Methodology for Modeling the Propagation of VLF Whistler Mode PLHR Waves Through the Ionosphere

   https://doi.org/10.1029/2024JA033273  

   Pedgaonkar, A S; Simpson, J J; Jensen, E A (February 2025, Journal of Geophysical Research: Space Physics)

   Abstract The finite‐difference time‐domain (FDTD) method was previously applied to high‐frequency electromagnetic wave propagation through 250 km of theFregion of the ionosphere. That modeling approach was limited to electromagnetic wave propagation above the critical frequency of the ionospheric plasma, and it did not include the lower ionosphere layers or the top of theF‐region. This paper extends the previous modeling methodology to frequencies below the critical frequency of the plasma and to altitudes encompassing the ionosphere. The following changes to the previous work were required to generate this model: (a) theD,Eand top of theFregions of the ionosphere were added; and (b) the perfectly matched layer absorbing boundary on the top side of the grid was replaced with a collisional plasma to prevent reflections. We apply this model to the study of extremely low frequency (ELF) and very low frequency (VLF) electric power line harmonic radiation (PLHR) through the ionosphere. The model is compared against analytical predictions and applied to PLHR propagation in polar, mid‐latitude and equatorial regions. Also, to further demonstrate the advantages of the grid‐based FDTD method, PLHR propagation through a polar cap patch with inhomogeneities is studied. The presented modeling methodology may be applied to additional scenarios in a straightforward manner and can serve as a useful tool for better tracking and studying electromagnetic wave propagation through the ionosphere at any latitude and in the presence of irregularities of any size and shape. 

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3. Statistical Properties of Dayside Whistler‐Mode Waves at Low Latitudes Under Various Solar Wind Conditions

   https://doi.org/10.1029/2024JA033225  

   Peng, Y.; Li, W.; Ma, Q.; Shen, X‐C (March 2025, Journal of Geophysical Research: Space Physics)

   Abstract While whistler‐mode waves are generated by injected anisotropic electrons on the nightside, the observed day‐night asymmetry of wave distributions raises an intriguing question about their generation on the dayside. In this study, we evaluate the distributions of whistler‐mode wave amplitudes and electrons as a function of distance from the magnetopause (MP) on the dayside from 6 to 18 hr in magnetic local time (MLT) within ±18° of magnetic latitude using the Time History of Events and Macroscale Interaction During Substorms measurements from June 2010 to August 2018. Specifically, under different levels of solar wind dynamic pressure and geomagnetic index, we conduct a statistical analysis to examine whistler‐mode wave amplitude, as well as anisotropy and phase space density (PSD) of source electrons across 1–20 keV energies, which potentially provide a source of free energy for wave generation. In coordinates relative to the MP, we find that lower‐band (0.05–0.5f_ce) waves occur much closer to the MP than upper‐band (0.5–0.8f_ce) waves, wheref_ceis electron cyclotron frequency. Our statistical results reveal that strong waves are associated with high anisotropy and high PSD of source electrons near the equator, indicating a preferred region for local wave generation on the dayside. Over 10–14 hr in MLT, as latitude increases, electron anisotropy decreases, while whistler‐mode wave amplitudes increase, suggesting that wave propagation from the equator to higher latitudes, along with amplification along the propagation path, is necessary to explain the observed waves on the dayside. 

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4. Global Model of Whistler Mode Chorus in the Near‐Equatorial Region (| λ _m |<  18°)

   https://doi.org/10.1029/2020GL087311  

   Meredith, Nigel P.; Horne, Richard B.; Shen, Xiao‐Chen; Li, Wen; Bortnik, Jacob (June 2020, Geophysical Research Letters)

   Abstract We extend our database of whistler mode chorus, based on data from seven satellites, by including ∼3 years of data from Radiation Belt Storm Probes (RBSP)‐A and RBSP‐B and an additional ∼6 years of data from Time History of Events and Macroscale Interactions during Substorms (THEMIS)‐A, THEMIS‐D, and THEMIS‐E. The new database allows us to probe the near‐equatorial region in detail, revealing new features. In the equatorial source region, |λ_m|<6°, strong wave power is most extensive in the 0.1–0.4f_cebands in the region 21–11 magnetic local time (MLT) from the plasmapause out toL^∗ = 8 and beyond, especially near dawn. At higher frequencies, in the 0.4–0.6f_cefrequency bands, strong wave power is more tightly confined, typically being restricted to the postmidnight sector in the region 4<L^∗<6. The global distribution of strong chorus wave power changes dramatically with increasing magnetic latitude, with strong chorus waves in the region 12<|λ_m|<18° predominantly observed at frequencies below 0.3f_cein the prenoon sector, in the region 5<L^∗<8. 

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5. Properties of the Stimulated Electromagnetic Emissions During the Inclined High‐Frequency Pumping of the Ionosphere Near the Fourth Electron Gyroharmonic at the High‐Frequency Active Auroral Research Program Facility

   https://doi.org/10.1029/2019GL082890  

   Shindin, A. V.; Grach, S. M.; Sergeev, E. N.; Smolina, V. P.; Pogorelko, N. A.; Bernhardt, P. A.; Briczinski, S. J.; Broughton, M.; LaBelle, J.; McCarrick, M. J. (June 2019, Geophysical Research Letters)

   Abstract Many phenomena in the high‐frequency pumped ionosphere exhibit dependence on the pump beam incident angleα. This motivates a systematic study of theαdependence of the stimulated electromagnetic emission (SEE), particularly near electron gyroharmonics. We report the first observations of stationary SEE spectra forαranging from −28° (north) to 28° (south) at three receiving sites, for the pump frequency (f₀) sweeping near the fourth gyroharmonic (4f_c). The following is established: (i) For pumping near the magnetic zenith (α= 7°, 14°, 21°), when existent dynamic broad upshifted maximum in the SEE spectrum indicates that artificial ionization layers are excited, suppression of the downshifted maximum atf₀≈ 4f_сis weakest, and 4f_сincreases. (ii) Weaker similar effects occur forα= −14° (a condition called “mirror magnetic zenith”). (iii) For northern pump beam inclinations, the SEE intensity decreases (in comparison with southern inclinations and vertical), most strongly at the southernmost receiving site. 

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