Statistical distribution of EMIC wave spectra: Observations from Van Allen Probes

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

doi:10.1002/2016GL071158

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Statistical distribution of EMIC wave spectra: Observations from Van Allen Probes

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Statistical distribution of EMIC wave spectra: Observations from Van Allen Probes

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

Geophysical research letters, Vol.43(24), pp.12,348-12,355

12/28/2016

DOI: 10.1002/2016GL071158

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Abstract

It has been known that electromagnetic ion cyclotron (EMIC) waves can precipitate ultrarelativistic electrons through cyclotron resonant scattering. However, the overall effectiveness of this mechanism has yet to be quantified, because it is difficult to obtain the global distribution of EMIC waves that usually exhibit limited spatial presence. We construct a statistical distribution of EMIC wave frequency spectra and their intensities based on Van Allen Probes measurements from September 2012 to December 2015. Our results show that as the ratio of plasma frequency over electron gyrofrequency increases, EMIC wave power becomes progressively dominated by the helium band. There is a pronounced dawn‐dusk asymmetry in the wave amplitude and the frequency spectrum. The frequency spectrum does not follow the commonly used single‐peak Gaussian function. Incorporating these realistic EMIC wave frequency spectra into radiation belt models is expected to improve the quantification of EMIC wave scattering effects in ultrarelativistic electron dynamics. Key Points Statistical distribution of the EMIC wave frequency spectrum is collected by using Van Allen Probes measurements The RMS EMIC wave amplitude becomes stronger with increasing levels of geomagnetic activity EMIC wave power is dominated by He‐band (H‐band) in high (low) fpe/fce regions

EMIC waves

magnetic storm

outer radiation belt

relativistic electron loss

Van Allen Probes

wave‐particle interaction

Details

Title: Subtitle: Statistical distribution of EMIC wave spectra: Observations from Van Allen Probes
Creators: X.‐J. Zhang - UCLA
W. Li - NOAA Oceanic and Atmospheric Research
R. M. Thorne - NOAA Oceanic and Atmospheric Research
V. Angelopoulos - University of California, Los Angeles
J. Bortnik - NOAA Oceanic and Atmospheric Research
C. A. Kletzing - University of Iowa
W. S. Kurth - University of Iowa
G. B. Hospodarsky - University of Iowa
Resource Type: Journal article
Publication Details: Geophysical research letters, Vol.43(24), pp.12,348-12,355
DOI: 10.1002/2016GL071158
ISSN: 0094-8276
eISSN: 1944-8007
Number of pages: 8
Grant note: AFOSR (FA9550‐15‐1‐0158) NASA's prime (NNN06AA01C) JHU/APL (131802) NASA (NAS5‐02099; NNX14AI18G; NNX13AI61G; NNX14AN85G) NSF (AGS 1564510)
Language: English
Date published: 12/28/2016
Academic Unit: Physics and Astronomy
Record Identifier: 9984429039002771

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