M. Yamauchi (IRF)Date:
AniaraIndependent Substorm Activations at Morning and Midnight Sectors
Swedish Institute of Space Physics
Both Viking and Cluster statistics of dayside plasma sheet (which is fossils of substorm activity) indicate that a substantial amount might have drifted from morning sector rather than from midnight. This finding is independently confirmed from two substorms studies, 2001-10-21 event and 2003-10-29 event. Both events are best possible substorms to examine the source location of the morning activity.
The first event is a unique one among Cluster plasma sheet observations because the dayside plasma sheet was formed during its traversal through the equatorial region. Inter-spacecraft dispersion analyses (this is a new technique) confirmed that the morning sector is the source of observed O+ and source of H+ dispersion at the substorm onset 30 minutes ago (substorm peak is midnight as seen by IMAGE). The second event a unique substorm in the recorded history in the sense that ground disturbance reached 2000 nT/4000 nT only 5 min/10 min after the arrival of solar wind shock (SC). This short response gives best identification of propagation route of substrom activation, and both ground magnetometer data and IMAGE auroral image show independent kernels at the midnight sector and early morning sector starting immediately after (< 1 min) the SC.
I mainly talk the first event (part of the statistics is reported last year), and if time allows, cover the second event.
Created 2006-10-19 13:33:15 by Mats HolmströmLast changed 2006-10-20 10:41:08 by Mats Holmström