Combined Scattering of Radiation Belt Electrons by Low‐Frequency Hiss: Cyclotron, Landau, and Bounce Resonances

We present and analyse a freely-available model of the power found in ultra-low frequency waves (ULF, 1-15 mHz) throughout Earth&#8217;s magnetosphere. Predictions can be used to test our understanding of magnetospheric dynamics, while accurate models of these waves are required to characterise the energisation and transport of radiation belt electrons in space weather.This model is constructed using decision tree ensembles, which iteratively partition the given parameter space into variable size bins. Wave power is determined by physical driving parameters (e.g. solar wind properties) and spatial parameters of interest (magnetic local time MLT, magnetic latitude and frequency). As a parameterised model, there is no guarantee that individual physical processes can be extracted and analysed. However, by iteratively considering smaller scale driving processes, we identify predominant wave drivers and find that solar wind driving of ULF waves are moderated by internal magnetospheric conditions. Significant remaining uncertainty occurs with mild solar wind driving, suggesting that the internal state of the magnetosphere should be included in future.Models such as this may be used to create global magnetospheric &#8220;maps&#8221; of predicted wave power which may then be used to create radial diffusion coefficients determining the effect of ULF waves on radiation belt electrons.

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Global models of the inner electron radiation belt and slot region investigating the effects of VLF transmitter waves

10.5194/egusphere-egu2020-4642 ◽

2020 ◽

Author(s):

Johnathan Ross ◽

Sarah Glauert ◽

Richard Horne ◽

Nigel Meredith ◽

Mark Clilverd

Keyword(s):

Radiation Belt ◽

Low Frequency ◽

Particle Interactions ◽

Electron Dynamics ◽

Global Models ◽

Inner Magnetosphere ◽

The Earth ◽

Radiation Belt Electrons ◽

Wave Particle Interactions ◽

Earth Orbits

Signals from man-made very low frequency (VLF) transmitters can leak from the Earth-ionosphere wave guide into the inner magnetosphere, where they propagate in the whistler mode and contribute to electron dynamics in the inner radiation belt and slot region through wave-particle interactions. These inner regions of the magnetosphere are becoming increasingly important from a satellite perspective. For instance, the newly populated Medium Earth Orbits pass though the slot region, and satellites launched via electric orbit raising are exposed to the inner belt and slot region for extended periods of time.We have calculated diffusion coefficients associated with wave-particle interactions between radiation belt electrons and waves from each of the strongest VLF transmitters using Van Allen Probe observations. These coefficients are included into global models of the radiation belts to assess the importance of the effects of VLF transmitters individually and collectively on electron populations.

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Estimating the Azimuthal Mode Structure of Ultra Low Frequency Waves and Its Effects on the Radial Diffusion of Radiation Belt Electrons

10.33915/etd.8244 ◽

2021 ◽

Author(s):

Mohammad Barani

Keyword(s):

Radiation Belt ◽

Low Frequency ◽

Radial Diffusion ◽

Mode Structure ◽

Azimuthal Mode ◽

Radiation Belt Electrons ◽

Low Frequency Waves

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A Comparison of Radial Diffusion Coefficients in 1-D and 3-D Long-Term Radiation Belt Simulations

10.5194/egusphere-egu2020-17757 ◽

2020 ◽

Author(s):

Alexander Drozdov ◽

Hayley Allison ◽

Yuri Shprits ◽

Nikita Aseev

Keyword(s):

Radiation Belt ◽

Low Frequency ◽

Radial Diffusion ◽

Ulf Waves ◽

Electron Radiation ◽

Particle Interactions ◽

Physical Mechanisms ◽

Modeling And Forecasting ◽

Radiation Belt Electrons

Radial diffusion is one of the dominant physical mechanisms that drives acceleration andloss of the radiation belt electrons due to wave-particle interactions with ultra-low frequency (ULF) waves, which makes it very important for radiation belt modeling and forecasting.&#160; We investigate the sensitivity of several parameterizations of the radial diffusion including Brautigam and Albert (2000), Ozeke et al. (2014), Ali et al. (2016), and Liu et al. (2016) on long-term radiation belt modeling using the Versatile Electron Radiation Belt (VERB) code.&#160; Following previous studies, we first perform 1-D radial diffusion simulations.&#160; To take into account effects of local acceleration and loss, we perform additional 3-D simulations, including pitch-angle, energy and mixed diffusion.

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A first approach to model the low-frequency wave activity in the plasmasphere

Annales Geophysicae ◽

10.5194/angeo-20-981-2002 ◽

2002 ◽

Vol 20 (7) ◽

pp. 981-996 ◽

Cited By ~ 23

Author(s):

R. André ◽

F. Lefeuvre ◽

F. Simonet ◽

U. S. Inan

Keyword(s):

Wave Field ◽

Radiation Belt ◽

Low Frequency ◽

Plasma Waves ◽

Particle Interactions ◽

Frequency Wave ◽

Magnetic Wave ◽

Amplitude Spectra ◽

Radiation Belt Electrons ◽

Instruments And Techniques

Abstract. A comprehensive empirical model of waves is developed in the objective to simulate wave-particle interactions involved in the loss and acceleration of radiation belt electrons. Three years of measured magnetic wave field components from the Plasma Wave Instrument on board the DE-1 satellite are used to model the amplitude spectral density of the magnetic wave field of each type of emission observed in the equatorial regions of the plasmasphere: VLF transmitter emissions, chorus emissions, plasmaspheric hiss emissions and equatorial emissions below ~ 200 Hz. Each model is a function of the wave frequency f , the MLT, L and Mlat parameters, and the Kp values. The performances of the plasmaspheric hiss and chorus models are tested on amplitude spectra recorded on board the OGO-5 and GEOS-1 satellites.Key words. Magnetospheric physics (plasmasphere; plasma waves and instabilities; instruments and techniques)

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