TY - JOUR
T1 - Statistical Study of Approaching Strong Diffusion of Low-Energy Electrons by Chorus and ECH Waves Based on In Situ Observations
AU - Fukizawa, M.
AU - Sakanoi, T.
AU - Miyoshi, Y.
AU - Kazama, Y.
AU - Katoh, Y.
AU - Kasahara, Y.
AU - Matsuda, S.
AU - Kumamoto, A.
AU - Tsuchiya, F.
AU - Matsuoka, A.
AU - Kurita, S.
AU - Nakamura, S.
AU - Shoji, M.
AU - Teramoto, M.
AU - Imajo, S.
AU - Shinohara, I.
AU - Wang, S. Y.
AU - Tam, S. W.Y.
AU - Chang, T. F.
AU - Wang, B. J.
AU - Jun, C. W.
N1 - Funding Information:
The development and operation of LEPe are partly funded by Academia Sinica and National Cheng Kung University of Taiwan and supported by the Ministry of Science and Technology of Taiwan under contract 106‐2111‐M‐001‐011 and 105‐3111‐Y‐001‐042. The first author is a Research Fellow of the Japan Society for the Promotion of Science (DC); this study is supported by JSPS Bilateral Open Partnership Joint Research Projects (JPJSBP120192504), JSPS KAKENHI Grant Nos. JP15H05815, JP17H00728, JP18H03727, JP20H01959, and JP20J11829 and conducted by the joint research program of the Institute for Space–Earth Environmental Research (ISEE), Nagoya University.
Publisher Copyright:
© 2022. American Geophysical Union. All Rights Reserved.
PY - 2022/3
Y1 - 2022/3
N2 - Inner magnetospheric electrons are precipitated in the ionosphere via pitch-angle (PA) scattering by lower band chorus (LBC), upper band chorus (UBC), and electrostatic electron cyclotron harmonic (ECH) waves. However, the PA scattering efficiency of low-energy electrons (0.1–10 keV) has not been investigated via in situ observations because of difficulties in flux measurements within loss cones at the magnetosphere. In this study, we demonstrate that LBC, UBC, and ECH waves contribute to PA scattering of electrons at different energy ranges using the Arase (ERG) satellite observation data and successively detected the moderate loss cone filling, that is, approaching strong diffusion. Approaching strong diffusion by LBC, UBC, and ECH waves occurred at ∼2–20 keV, ∼1–10 keV, and ∼0.1–2 keV, respectively. The occurrence rate of the approaching strong diffusion by high-amplitude LBC (>50 pT), UBC (>20 pT), and ECH (>10 mV/m) waves, respectively, reached ∼70%, ∼40%, and ∼30% higher than that without simultaneous wave activity. The energy range in which the occurrence rate was high agreed with the range where the PA diffusion rate of each wave exceeded the strong diffusion level based on the quasilinear theory.
AB - Inner magnetospheric electrons are precipitated in the ionosphere via pitch-angle (PA) scattering by lower band chorus (LBC), upper band chorus (UBC), and electrostatic electron cyclotron harmonic (ECH) waves. However, the PA scattering efficiency of low-energy electrons (0.1–10 keV) has not been investigated via in situ observations because of difficulties in flux measurements within loss cones at the magnetosphere. In this study, we demonstrate that LBC, UBC, and ECH waves contribute to PA scattering of electrons at different energy ranges using the Arase (ERG) satellite observation data and successively detected the moderate loss cone filling, that is, approaching strong diffusion. Approaching strong diffusion by LBC, UBC, and ECH waves occurred at ∼2–20 keV, ∼1–10 keV, and ∼0.1–2 keV, respectively. The occurrence rate of the approaching strong diffusion by high-amplitude LBC (>50 pT), UBC (>20 pT), and ECH (>10 mV/m) waves, respectively, reached ∼70%, ∼40%, and ∼30% higher than that without simultaneous wave activity. The energy range in which the occurrence rate was high agreed with the range where the PA diffusion rate of each wave exceeded the strong diffusion level based on the quasilinear theory.
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U2 - 10.1029/2022JA030269
DO - 10.1029/2022JA030269
M3 - Article
AN - SCOPUS:85127363232
SN - 2169-9402
VL - 127
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
IS - 3
M1 - e2022JA030269
ER -