Open AccessLarge electric field at the nightside plasmapause observed by the Polar spacecraft
Author(s) -
Kim K.H.,
Mozer F. S.,
Lee D.H.,
Jin H.
Publication year - 2010
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2010ja015439
Subject(s) - plasmasphere , physics , electric field , magnetosphere , earth's magnetic field , geophysics , magnetic field , polar , ionosphere , substorm , field line , perturbation (astronomy) , computational physics , astronomy , quantum mechanics
We report an example of large electric field with a peak amplitude of ∼60 mV/m observed at the plasmapause by the Polar spacecraft on April 25, 1998. This electric field pointed radially outward and predominantly perpendicular to the ambient magnetic field. As comparing the plasmapause crossings in the previous and following Polar passes, we found that the large electric field is associated with forming a sharp plasmapause structure. Comparing with previous observations of subauroral electric fields in the ionosphere and magnetosphere, we suggest that the large electric field observed at Polar is associated with the subauroral ion drift phenomenon. In addition, we observed a negative‐then‐positive magnetic field perturbation at the plasmapause. That is, the magnetic field is reduced outside the plasmapause and enhanced inside the plasmapause. The field perturbation is dominant in the meridional plane. We suggest that the magnetic field perturbation is due to the dawnward plasmapause current ( J pp ), which is associated with the balance of forces (∇ P ∼ J pp × B ) at the plasmapause, perpendicular to the background magnetic field.