Open AccessOn the simultaneity of substorm onset between two hemispheres
Author(s) -
Morioka A.,
Miyoshi Y.,
Tsuchiya F.,
Misawa H.,
Kasaba Y.,
Asozu T.,
Okano S.,
Kadokura A.,
Sato N.,
Miyaoka H.,
Yumoto K.,
Parks G. K.,
Honary F.,
Trotig J. G.,
Décréau P. M. E.,
Reinisch B. W.
Publication year - 2011
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 - 10.1029/2010ja016174
Subject(s) - substorm , breakup , geophysics , northern hemisphere , ionosphere , geology , southern hemisphere , physics , atmospheric sciences , magnetosphere , magnetic field , climatology , mechanics , quantum mechanics
Simultaneous observations of auroral kilometric radiation from the Northern and Southern Hemispheres showed some cases in which the buildup of field‐aligned acceleration occurred only in one hemisphere at the substorm onset. This indicates that a substorm does not always complete the current system by connecting the cross‐tail current with both northern and southern ionospheric currents. Conjugate auroral observations showed that in one case, the auroral breakup in the Northern and Southern Hemispheres was not simultaneous; rather, they occurred a few minutes apart. This time difference in the breakup between two hemispheres suggests that the local auroral ionosphere controls auroral breakup in each hemisphere independently. The evidence in this study may indicate that the buildup of the field‐aligned acceleration region at the auroral breakup does not result only from the magnetospheric process and that the auroral ionosphere finally controls and/or ignites the substorm onset, that is, the auroral breakup.