TY  - JOUR
A1  - Cao, Xing
A1  - Ni, Binbin
A1  - Summers, Danny
A1  - Shprits, Yuri Y.
A1  - Gu, Xudong
A1  - Fu, Song
A1  - Lou, Yuequn
A1  - Zhang, Yang
A1  - Ma, Xin
A1  - Zhang, Wenxun
A1  - Huang, He
A1  - Yi, Juan
T1  - Sensitivity of EMIC wave-driven scattering loss of ring current protons to wave normal angle distribution
JF  - Geophysical research letters
N2  - Electromagnetic ion cyclotron waves have long been recognized to play a crucial role in the dynamic loss of ring current protons. While the field-aligned propagation approximation of electromagnetic ion cyclotron waves was widely used to quantify the scattering loss of ring current protons, in this study, we find that the wave normal distribution strongly affects the pitch angle scattering efficiency of protons. Increase of peak normal angle or angular width can considerably reduce the scattering rates of <= 10 keV protons. For >10 keV protons, the field-aligned propagation approximation results in a pronounced underestimate of the scattering of intermediate equatorial pitch angle protons and overestimates the scattering of high equatorial pitch angle protons by orders of magnitude. Our results suggest that the wave normal distribution of electromagnetic ion cyclotron waves plays an important role in the pitch angle evolution and scattering loss of ring current protons and should be incorporated in future global modeling of ring current dynamics.
Y1  - 2019
U6  - https://doi.org/10.1029/2018GL081550
SN  - 0094-8276
SN  - 1944-8007
VL  - 46
IS  - 2
SP  - 590
EP  - 598
PB  - American Geophysical Union
CY  - Washington
ER  -