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THEMIS Significant results from 2 years of operations. A simpler task: Distinguish Between Two Models for Substorm Onset. Magnetic Reconnection: Explosion at 25R E. Current Disruption: Implosion at 10R E. Substorm Science on THEMIS: Probe Alignments and Ground Conjunctions.
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THEMIS Significant results from 2 years of operations
A simpler task: Distinguish BetweenTwo Models for Substorm Onset Magnetic Reconnection: Explosion at 25RE Current Disruption: Implosion at 10RE
Substorm Science on THEMIS:Probe Alignments and Ground Conjunctions Simulation: J. Raeder, UNH Visualization: Tom Bridgman,GSFC/SVS Vassilis Angelopoulos, UCLA ESS April 13, 2006
: Ground Based Observatory THEMIS Mission elements Probe conjunctions along Sun-Earth line: 4 day recurrence over ground based observatories … while THEMIS’s space-based probes determine onset of Current Disruption and Reconnection each within <10s. Ground based observatories completely cover North American sector; determine auroral breakup within 1-3s …
TRx 2nd 2nd 1st 1st 3rd 3rd TAI TCD Timing of ground and space: Ground (3 cameras):
P1 P2 2nd 1st 3rd Substorm Timing 1st Tail Season (2008) Science Cover Story Angelopoulos et al., Science, 2008 (Also: Pu et al., JGR 2009, Gabrielse et al., 2009, Liu et al., 2009, others) Low energy electrons High energy electrons Flow Ions
Macroscale Interactions 2nd tail season (2009) • Dipolarization fronts link Rx site to injection fronts • Self-similar structures over global scales • Front of ion-inertial length in scale, kinetic in nature ~3 min 300 km/s
2nd 2nd 2nd 1st 1st 1st 3rd 3rd 3rd Summary Note: this is not the classical time sequence: Aurora brightens before near Earth dipolarization This holds true on several events considered Outside-In model Inside out model Reconnection Aurora Current Disruption THEMIS finds: