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Bounce resonance scattering of radiation belt electrons by H+ band EMIC waves

Cao X., B. Ni, D. Summers, J. Bortnik, X. Tao, Y. Y. Shprits, Y. Lou, X. Gu, S. Fu, R. Shi, Z. Xiang, Q. Wang, (2017), Bounce resonance scattering of radiation belt electrons by H+ band EMIC waves, J. of Geophys. Res. [Space Physics], 122, 1702-1713, doi:10.1002/2016JA023607

Abstract

Abstract We perform a detailed analysis of bounce-resonant pitch angle scattering of radiation belt electrons due to electromagnetic ion cyclotron (EMIC) waves. It is found that EMIC waves can resonate with near-equatorially mirroring electrons over a wide range of L shells and energies. H+ band EMIC waves efficiently scatter radiation belt electrons of energy >100 keV from near 90° pitch angles to lower pitch angles where the cyclotron resonance mechanism can take over to further diffuse electrons into the loss cone. Bounce-resonant electron pitch angle scattering rates show a strong dependence on L shell, wave normal angle distribution, and wave spectral properties. We find distinct quantitative differences between EMIC wave-induced bounce-resonant and cyclotron-resonant diffusion coefficients. Cyclotron-resonant electron scattering by EMIC waves has been well studied and found to be a potentially crucial electron scattering mechanism. The new investigation here demonstrates that bounce-resonant electron scattering may also be very important. We conclude that bounce resonance scattering by EMIC waves should be incorporated into future modeling efforts of radiation belt electron dynamics.

Authors (sorted by name)

Bortnik Cao Fu Gu Lou Ni Shprits Summers Tao Xiang

Journal / Conference

Journal Of Geophysical Research (Space Physics)

Acknowledgments

This work was supported by the NSFC grants 41674163, 41474141, and 41204120. No observational data were used in the present study. D.S. holds the position of overseas prominent professor at Wuhan University and wishes to thank the Department of Space Physics for the excellent hospitality during his visits. D.S. also acknowledges support from a discovery grant of the Natural Sciences and Engineering Research Council of Canada. X.T. would like to acknowledge the support by NSFC grant 41474142. J.B. would like to acknowledge grants NNX13AI61G and NNX14AN85G.

Grants

NNX13AI61G NNX14AN85G

Bibtex

@article{doi:10.1002/2016JA023607,
author = {Cao, Xing and Ni, Binbin and Summers, Danny and Bortnik, Jacob and Tao, Xin and Shprits, Yuri Y. and Lou, Yuequn and Gu, Xudong and Fu, Song and Shi, Run and Xiang, Zheng and Wang, Qi},
title = {Bounce resonance scattering of radiation belt electrons by H+ band EMIC waves},
journal = {Journal of Geophysical Research: Space Physics},
volume = {122},
year = {2017},
number = {2},
pages = {1702-1713},
keywords = {bounce resonance, electromagnetic ion cyclotron waves, radiation belt electrons, resonant wave-particle interactions},
doi = {10.1002/2016JA023607},
url = {https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2016JA023607},
eprint = {https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2016JA023607},
abstract = {Abstract We perform a detailed analysis of bounce-resonant pitch angle scattering of radiation belt electrons due to electromagnetic ion cyclotron (EMIC) waves. It is found that EMIC waves can resonate with near-equatorially mirroring electrons over a wide range of L shells and energies. H+ band EMIC waves efficiently scatter radiation belt electrons of energy >100 keV from near 90° pitch angles to lower pitch angles where the cyclotron resonance mechanism can take over to further diffuse electrons into the loss cone. Bounce-resonant electron pitch angle scattering rates show a strong dependence on L shell, wave normal angle distribution, and wave spectral properties. We find distinct quantitative differences between EMIC wave-induced bounce-resonant and cyclotron-resonant diffusion coefficients. Cyclotron-resonant electron scattering by EMIC waves has been well studied and found to be a potentially crucial electron scattering mechanism. The new investigation here demonstrates that bounce-resonant electron scattering may also be very important. We conclude that bounce resonance scattering by EMIC waves should be incorporated into future modeling efforts of radiation belt electron dynamics.}
}