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Subsolar magnetopause observation and kinetic simulation of a tripolar guide magnetic field perturbation consistent with a magnetic island
Author(s) -
Eriksson S.,
Cassak P. A.,
Retinò A.,
Mozer F. S.
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl068691
Subject(s) - magnetopause , magnetic field , physics , geophysics , solar wind , perturbation (astronomy) , computational physics , magnetic reconnection , polar , magnetosphere , interplanetary magnetic field , field (mathematics) , field line , dipole model of the earth's magnetic field , astronomy , mathematics , quantum mechanics , pure mathematics
The Polar satellite recorded two reconnection exhausts within 6 min on 1 April 2001 across a subsolar magnetopause that displayed a symmetric plasma density, but different out‐of‐plane magnetic field signatures for similar solar wind conditions. The first magnetopause crossing displayed a bipolar guide field variation in a weak external guide field consistent with a symmetric Hall field from a single X line. The subsequent crossing represents the first observation of a tripolar guide field perturbation at Earth's magnetopause in a strong guide field. This perturbation consists of a significant guide field enhancement between two narrow guide field depressions. A particle‐in‐cell simulation for the prevailing conditions across this second event resulted in a magnetic island between two simulated X lines across which a tripolar guide field developed consistent with the observation. The simulated island supports a scenario whereby Polar encountered the asymmetric quadrupole Hall magnetic fields between two X lines for symmetric conditions across the magnetopause.