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Title: Direct evidence for EMIC wave scattering of relativistic electrons in space: EMIC-Driven Electron Losses in Space

Electromagnetic ion cyclotron (EMIC) waves have been proposed to cause efficient losses of highly relativistic (>1 MeV) electrons via gyroresonant interactions. Simultaneous observations of EMIC waves and equatorial electron pitch angle distributions, which can be used to directly quantify the EMIC wave scattering effect, are still very limited, however. In the present study, we evaluate the effect of EMIC waves on pitch angle scattering of ultrarelativistic (>1 MeV) electrons during the main phase of a geomagnetic storm, when intense EMIC wave activity was observed in situ (in the plasma plume region with high plasma density) on both Van Allen Probes. EMIC waves captured by Time History of Events and Macroscale Interactions during Substorms (THEMIS) probes and on the ground across the Canadian Array for Real-time Investigations of Magnetic Activity (CARISMA) are also used to infer their magnetic local time (MLT) coverage. From the observed EMIC wave spectra and local plasma parameters, we compute wave diffusion rates and model the evolution of electron pitch angle distributions. In conclusion, by comparing model results with local observations of pitch angle distributions, we show direct, quantitative evidence of EMIC wave-driven relativistic electron losses in the Earth’s outer radiation belt.
Authors:
 [1] ;  [2] ; ORCiD logo [2] ;  [2] ;  [3] ;  [2] ;  [4] ;  [5] ;  [5] ;  [5] ;  [6] ; ORCiD logo [7] ;  [8] ;  [9] ;  [9]
  1. Univ. of California, Los Angeles, CA (United States). Dept. of Atmospheric and Oceanic Sciences; Univ. of California, Los Angeles, CA (United States). Dept. of Earth, Planetary, and Space Sciences and Inst. of Geophysics and Space Physics
  2. Univ. of California, Los Angeles, CA (United States). Dept. of Atmospheric and Oceanic Sciences
  3. Univ. of California, Los Angeles, CA (United States). Dept. of Earth, Planetary, and Space Sciences and Inst. of Geophysics and Space Physics
  4. Univ. of Texas at Dallas, Richardson, TX (United States). Dept. of Physics
  5. Univ. of Iowa, Iowa City, IA (United States). Dept. of Physics and Astronomy
  6. Univ. of Colorado, Boulder, CO (United States). Lab. for Atmospheric and Space Research
  7. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); New Mexico Consortium, Los Alamos, NM (United States). Space Sciences Division
  8. Univ. of New Hampshire, Durham, NH (United States). Inst. for the Study of Earth, Oceans, and Space
  9. Aerospace Corporation, Los Angeles, CA (United States)
Publication Date:
Report Number(s):
LA-UR-16-23135
Journal ID: ISSN 2169-9380; TRN: US1703009
Grant/Contract Number:
AC52-06NA25396; 967399; 921647; NAS5-01072; NNX15AI96G; NNX15AF61G; NNX11AR64G; NNX13AI61G; NNX14AI18G; FA9550-15-1-0158; AGS 1564510
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Space Physics
Additional Journal Information:
Journal Volume: 121; Journal Issue: 7; Journal ID: ISSN 2169-9380
Publisher:
American Geophysical Union
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
National Aeronautic and Space Administration (NASA); USDOE
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Heliospheric and Magnetospheric Physics; EMIC waves; relativistic electron loss; wave-particle interaction; Fokker-Planck equation; electron precipitation; equatorial pitch angle distribution
OSTI Identifier:
1402611

Zhang, X. -J., Li, W., Ma, Q., Thorne, R. M., Angelopoulos, V., Bortnik, J., Chen, L., Kletzing, C. A., Kurth, W. S., Hospodarsky, G. B., Baker, D. N., Reeves, G. D., Spence, H. E., Blake, J. B., and Fennell, J. F.. Direct evidence for EMIC wave scattering of relativistic electrons in space: EMIC-Driven Electron Losses in Space. United States: N. p., Web. doi:10.1002/2016JA022521.
Zhang, X. -J., Li, W., Ma, Q., Thorne, R. M., Angelopoulos, V., Bortnik, J., Chen, L., Kletzing, C. A., Kurth, W. S., Hospodarsky, G. B., Baker, D. N., Reeves, G. D., Spence, H. E., Blake, J. B., & Fennell, J. F.. Direct evidence for EMIC wave scattering of relativistic electrons in space: EMIC-Driven Electron Losses in Space. United States. doi:10.1002/2016JA022521.
Zhang, X. -J., Li, W., Ma, Q., Thorne, R. M., Angelopoulos, V., Bortnik, J., Chen, L., Kletzing, C. A., Kurth, W. S., Hospodarsky, G. B., Baker, D. N., Reeves, G. D., Spence, H. E., Blake, J. B., and Fennell, J. F.. 2016. "Direct evidence for EMIC wave scattering of relativistic electrons in space: EMIC-Driven Electron Losses in Space". United States. doi:10.1002/2016JA022521. https://www.osti.gov/servlets/purl/1402611.
@article{osti_1402611,
title = {Direct evidence for EMIC wave scattering of relativistic electrons in space: EMIC-Driven Electron Losses in Space},
author = {Zhang, X. -J. and Li, W. and Ma, Q. and Thorne, R. M. and Angelopoulos, V. and Bortnik, J. and Chen, L. and Kletzing, C. A. and Kurth, W. S. and Hospodarsky, G. B. and Baker, D. N. and Reeves, G. D. and Spence, H. E. and Blake, J. B. and Fennell, J. F.},
abstractNote = {Electromagnetic ion cyclotron (EMIC) waves have been proposed to cause efficient losses of highly relativistic (>1 MeV) electrons via gyroresonant interactions. Simultaneous observations of EMIC waves and equatorial electron pitch angle distributions, which can be used to directly quantify the EMIC wave scattering effect, are still very limited, however. In the present study, we evaluate the effect of EMIC waves on pitch angle scattering of ultrarelativistic (>1 MeV) electrons during the main phase of a geomagnetic storm, when intense EMIC wave activity was observed in situ (in the plasma plume region with high plasma density) on both Van Allen Probes. EMIC waves captured by Time History of Events and Macroscale Interactions during Substorms (THEMIS) probes and on the ground across the Canadian Array for Real-time Investigations of Magnetic Activity (CARISMA) are also used to infer their magnetic local time (MLT) coverage. From the observed EMIC wave spectra and local plasma parameters, we compute wave diffusion rates and model the evolution of electron pitch angle distributions. In conclusion, by comparing model results with local observations of pitch angle distributions, we show direct, quantitative evidence of EMIC wave-driven relativistic electron losses in the Earth’s outer radiation belt.},
doi = {10.1002/2016JA022521},
journal = {Journal of Geophysical Research. Space Physics},
number = 7,
volume = 121,
place = {United States},
year = {2016},
month = {7}
}