Open AccessSubauroral proton spots visualize the Pc1 source
Author(s) -
Yahnin A. G.,
Yahnina T. A.,
Frey H. U.
Publication year - 2007
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 - 10.1029/2007ja012501
Subject(s) - plasmasphere , physics , proton , magnetosphere , ring current , cyclotron , earth's magnetic field , whistler , ionosphere , geophysics , astrophysics , computational physics , nuclear physics , magnetic field , plasma , quantum mechanics
Recent observations from the IMAGE spacecraft revealed a new type of proton aurora – subauroral proton spots, which map onto the vicinity of the plasmapause. It has been suggested that this proton aurora is produced by energetic proton precipitation after the interaction of ring current particles with electromagnetic ion cyclotron (EMIC) waves in the equatorial plane of the magnetosphere. We prove this suggestion by comparing observations from IMAGE with geomagnetic pulsations Pc1, which are a ground signature of EMIC waves. We found that when the proton spot is nearly conjugated with the ground station equipped with a pulsation magnetometer, the station always observes Pc1. Moreover, there is a good agreement between the appearance/disappearance of the spot and the beginning/end of the Pc1 train. We conclude that the subauroral proton spots are images on the ionospheric “screen” of magnetospheric regions where the ion cyclotron instability develops leading to an intense scattering of energetic protons into the loss cone.