Research output: Contribution to journal › Article › peer-review
Categorization of electron isotropy boundary patterns: ELFIN and POES observations. / Artemyev, Anton; Сергеев, Виктор Андреевич; Angelopoulos, V.; Wilkins, C.; Zhang, X. J.
In: Journal of Geophysical Research: Space Physics, Vol. 129, No. 11, e2024JA033231, 30.11.2024.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - Categorization of electron isotropy boundary patterns: ELFIN and POES observations
AU - Artemyev, Anton
AU - Сергеев, Виктор Андреевич
AU - Angelopoulos, V.
AU - Wilkins, C.
AU - Zhang, X. J.
PY - 2024/11/30
Y1 - 2024/11/30
N2 - Magnetic field-line curvature scattering (FLCS) of energetic particles in the equatorial magnetotail results in isotropization of pitch-angle distributions, loss-cone filling, and precipitation above a minimum energy at a given latitude. At a fixed energy, the lowest latitude of isotropization is the isotropy boundary (IB) for that energy. Nominally, the IB (latitude) exhibits a characteristic energy dependence due to the monotonic variation of the equatorial magnetic field intensity with radial distance. Deviations from this nominal IB dispersion can occur if the radial variation (spatial or temporal) is non-mononotic and/or if other precipitation mechanisms prevail. With its sensitive and detailed measurements of electron spectra up to relativistic energies, ELFIN's recent observations reveal a variety of electron IBe patterns near magnetic midnight which are repeatable enough to warrant classification. This study aims to categorize the various IBe patterns observed by ELFIN's high-fidelity but short lived dataset (a few months), compare them with simultaneous nearby POES observations, which are made with a limited energy coverage and resolution but last for decades, and discuss their possible interpretation. The general agreement between ELFIN and POES IB observations indicate a relatively large-scale nature of IBe patterns. Surprisingly, there exists a large number (up to 2/3 of all events) of non-monotonic-or steep/multiple-IB patterns. This suggest an abundance of non-trivial tail current sheet structures or a mixed contribution of two mechanisms in the vicinity of IBe in these cases.
AB - Magnetic field-line curvature scattering (FLCS) of energetic particles in the equatorial magnetotail results in isotropization of pitch-angle distributions, loss-cone filling, and precipitation above a minimum energy at a given latitude. At a fixed energy, the lowest latitude of isotropization is the isotropy boundary (IB) for that energy. Nominally, the IB (latitude) exhibits a characteristic energy dependence due to the monotonic variation of the equatorial magnetic field intensity with radial distance. Deviations from this nominal IB dispersion can occur if the radial variation (spatial or temporal) is non-mononotic and/or if other precipitation mechanisms prevail. With its sensitive and detailed measurements of electron spectra up to relativistic energies, ELFIN's recent observations reveal a variety of electron IBe patterns near magnetic midnight which are repeatable enough to warrant classification. This study aims to categorize the various IBe patterns observed by ELFIN's high-fidelity but short lived dataset (a few months), compare them with simultaneous nearby POES observations, which are made with a limited energy coverage and resolution but last for decades, and discuss their possible interpretation. The general agreement between ELFIN and POES IB observations indicate a relatively large-scale nature of IBe patterns. Surprisingly, there exists a large number (up to 2/3 of all events) of non-monotonic-or steep/multiple-IB patterns. This suggest an abundance of non-trivial tail current sheet structures or a mixed contribution of two mechanisms in the vicinity of IBe in these cases.
KW - electron precipitations
KW - isotropy boundary
KW - magnetotail current sheet
UR - https://www.mendeley.com/catalogue/9a9e985f-6d2e-365d-bd9f-4b3e6ed3e20f/
U2 - 10.1029/2024JA033231
DO - 10.1029/2024JA033231
M3 - Article
VL - 129
JO - Journal of Geophysical Research: Space Physics
JF - Journal of Geophysical Research: Space Physics
SN - 2169-9380
IS - 11
M1 - e2024JA033231
ER -
ID: 128114559