Journal article
Time Scales for Electron Quasi‐linear Diffusion by Lower‐Band Chorus Waves: The Effects of ωpe/Ωce Dependence on Geomagnetic Activity
Geophysical research letters, Vol.46(12), pp.6178-6187
06/28/2019
DOI: 10.1029/2019GL083446
Abstract
Electron scattering by chorus waves is an important mechanism that can lead to fast electron acceleration and loss in the outer radiation belt. Making use of Van Allen Probes measurements, we present the first statistical survey of megaelectron volt electron pitch angle and energy quasi‐linear diffusion rates by chorus waves as a function of L‐shell, local time, and AE index, taking into account the local electron plasma frequency to gyrofrequency ratio ωpe/Ωce, chorus wave frequency, and resonance wave amplitude. We demonstrate that during disturbed periods, ωpe/Ωce strongly decreases in the night sector, leading to a faster electron loss but also a much faster electron energization in two distinct regions just above the plasmapause and at L ~ 3.5–5.5. Spatiotemporal variations of ωpe/Ωce with AE shape the evolution of electron energization in the outer belt, sometimes leading to very short time scales for quasi‐linear megaelectron volt electron acceleration in agreement with Van Allen Probes observations.
Key Points
The wpe/wce ratio varies significantly during active geomagnetic conditions especially in the night sector (decreasing from 3.5 to 1.2–1.4)
Variations of wpe/wce change the resonance conditions for wave‐particle interactions of relativistic electrons with chorus waves
Effects of wpe/wce decrease lead to intensification of quasi‐linear diffusion and decrease of time scales to 1–3 hr during active events
Details
- Title: Subtitle
- Time Scales for Electron Quasi‐linear Diffusion by Lower‐Band Chorus Waves: The Effects of ωpe/Ωce Dependence on Geomagnetic Activity
- Creators
- O. Agapitov - University of California, BerkeleyD. Mourenas - CEA DAM Île-de-FranceA. Artemyev - University of California, Los AngelesG. Hospodarsky - University of IowaJ.W. Bonnell - University of California, Berkeley
- Resource Type
- Journal article
- Publication Details
- Geophysical research letters, Vol.46(12), pp.6178-6187
- DOI
- 10.1029/2019GL083446
- ISSN
- 0094-8276
- eISSN
- 1944-8007
- Number of pages
- 10
- Grant note
- JHU/APL (922613) NASA (NNX16AF85G; 80NSSC19K0848)
- Language
- English
- Date published
- 06/28/2019
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984455559402771
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