We performe
d a multi-instrument groun
d-base
d an
d satellite stu
dy of substorm-relate
d phenomena
during auroral breakup. Our stu
dy is limite
d to the short (a few minutes) time interval aroun
d the breakup onset. A mapping ma
de on the basis of event-oriente
d mangnetospheric mo
del places the pre-breakup arc into the near-Earth region (
r
der=0 SRC=/images/glyphs/BQ4.GIF> 10 RE) where thin an
d intense current sheet
develops. Disruption of the current sheet was observe
d in the same region. The plasmoi
d was observe
d in the mi
d-tail. Backtracing the plasmoi
d onset time an
d location confirme
d that reconnection relate
d to the substorm onset coul
d operate in the near-Earth thin current sheet. These observations are in agreement with the i
dea that the reconnection an
d current
disruption signatures, as well as auroral breakup are
different manifestations of the one process.