Properties of Intense Field‐Aligned Lower‐Band Chorus Waves: Implications for Nonlinear Wave‐Particle Interactions

X.‐J Zhang; R Thorne; A Artemyev; D Mourenas; V Angelopoulos; J Bortnik; C. A Kletzing; W. S Kurth; G. B Hospodarsky

doi:10.1029/2018JA025390

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Properties of Intense Field‐Aligned Lower‐Band Chorus Waves: Implications for Nonlinear Wave‐Particle Interactions

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Properties of Intense Field‐Aligned Lower‐Band Chorus Waves: Implications for Nonlinear Wave‐Particle Interactions

X.‐J Zhang, R Thorne, A Artemyev, D Mourenas, V Angelopoulos, J Bortnik, C. A Kletzing, W. S Kurth and G. B Hospodarsky

Journal of geophysical research. Space physics, Vol.123(7), pp.5379-5393

07/2018

DOI: 10.1029/2018JA025390

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Abstract

Resonant interactions between electrons and chorus waves are responsible for a wide range of phenomena in near‐Earth space (e.g., diffuse aurora and acceleration of > 1 MeV electrons). Although quasi‐linear diffusion is believed to be the primary paradigm for describing such interactions, an increasing number of investigations suggest that nonlinear effects are also important in controlling the rapid dynamics of electrons. However, present models of nonlinear wave‐particle interactions, which have been successfully used to describe individual short‐term events, are not directly applicable for a statistical evaluation of nonlinear effects and the long‐term dynamics of the outer radiation belt, because they lack information on the properties of intense (nonlinearly resonating with electrons) chorus waves. In this paper, we use the Time History of Events and Macroscale Interactions during Substorms and Van Allen Probes data sets of field‐aligned chorus waveforms to study two key characteristics of these waves: effective amplitude ℬw (nonlinear interaction can occur when ℬw>2) and wave packet length β (the number of wave periods within it). While as many as 10–15% of chorus wave packets are sufficiently intense ( ℬw>2–3) to interact nonlinearly with relativistic electrons, most of them are short (β < 10) reducing the efficacy of such interactions. Revised models of nonlinear interactions are thus needed to account for the long‐term effects of these common, intense but short chorus wave packets. We also discuss the dependence of ℬw, β on location (MLT and L‐shell) and on the properties of the suprathermal electron population. Key Points The occurrence rate of lower‐band chorus waves interacting nonlinearly with electrons is estimated Statistics on the fraction of intense lower‐band chorus wave packets are given The important role of suprathermal electrons for intense chorus wave packet characteristics is shown

Statistics

chorus waves

effective amplitude

nonlinear wave‐particle interaction

spatial distribution

wave packet length

Details

Title: Subtitle: Properties of Intense Field‐Aligned Lower‐Band Chorus Waves: Implications for Nonlinear Wave‐Particle Interactions
Creators: X.‐J Zhang - University of California
R Thorne - University of California, Los Angeles
A Artemyev - Russian Academy of Sciences
D Mourenas - CEA, DAM, DIF Arpajon France
V Angelopoulos - University of California, Los Angeles
J Bortnik - University of California, Los Angeles
C. A Kletzing - University of Iowa
W. S Kurth - University of Iowa
G. B Hospodarsky - University of Iowa
Resource Type: Journal article
Publication Details: Journal of geophysical research. Space physics, Vol.123(7), pp.5379-5393
DOI: 10.1029/2018JA025390
ISSN: 2169-9380
eISSN: 2169-9402
Number of pages: 15
Grant note: NASA (NNX16AG21G; DE-SC0010578; AFOSR FA9550-15-1-0158) NASA (NAS5-02099) Johns Hopkins University Applied Physics Laboratory
Language: English
Date published: 07/2018
Academic Unit: Physics and Astronomy
Record Identifier: 9984200059702771

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