1. First 10 months (Feb 2007-Dec 2007)
Prime mission at a glance (FY07-FY09)
First 10 months (Feb 2007-Dec 2007)
TH-B
TH-C
TH-D
TH-E
TH-A P1 P2 P3 P4 P5
First year baseline orbit (FY08)
Tail
YGSE
Dayside
Launch=
XGSE
Second year baseline orbit (FY09)
Tail
Dayside

2. Discovery of entry mechanism of cold dense magnetospheric plasma
First dissection of
a detached FTE
Discoveries
Dusk MP
Sphere
Sheath
Sibeck et al., GRL, 2008
Discovery of entry mechanism
of cold dense magnetospheric plasma
Oieroset et al., GRL, 2008; Li et al., JGR 2008
Liu et al., GRL, 2008
First detection of remote signatures of FTE's

3. A comparison between the electric field and –Vi x B, observed by THEMIS during the current sheet thinning. Their remarkable disagreement indicates violation of the “frozen-in” condition (presented by J. McFadden et al.).

4. Substorm study on Feb 26, 2008
Substorm onset Auroral signature
Probe locations

5. Other substorm signatures:
Currents, Pulsations

6. Tail substorm signatures: Fields, Flows, DistributionsV┴ V║ P1 P2
ions V┴ P1 P2
electrons V║
Electrons:
Similar to Hoshino et al., 2001
Ions: Similar to Hoshino et al., 1998

7. Middle Panels: Transformation to
deHoffman-Teller frame
Bottom panels: Walen test of stress balance
Caveats:
Need to include energetic particle contribution to velocity
Aliasing from temporal variations
Note: When peak velocity considered
match to Alfven speed is better

8. TRx TAI TCD 3rd 1st 2nd 3rd 1st 2nd Timing on the ground and in space:
electrons
ions
3rd
1st
2nd

9. 2nd 1st 3rd Inside out model Outside-In model 2nd 1st 3rd 3rd 2nd 1st
Note: this is not the classical time sequence:
Aurora brightens before near Earth dipolarization
This holds true on several events considered
(Gabrielse et al; 2008; Liu et al., 2008; Runov et al., 2008; Mende et al., 2008)
Inside out model
Outside-In model
2nd
1st
3rd
3rd
2nd
1st
Reconnection
Aurora
Current Disruption
3rd
1st
2nd

10. Summary, Future Work and Implications
On several events when THEMIS was well positioned, reconnection preceded substorm onset and current disruption.
Need to understand generality of results (next winter)
Are spontaneous and externally driven substorms different?
Are very low latitude onsets (65o) different from these (67o-68o)
On all events the aurora responded too quickly (~90s) for Alfven wave communication. Need to investigate coupling mechanism:
Dispersive Alfven waves, whistlers or electrons can travel fast enough.
IMPLICATIONS
Spontaneous reconnection can be destabilized but how?
Need to understand instability preconditioning, criterion, drivers
Study how pre-substorm aurora maps to the tail
How is growth phase aurora created
How do field aligned currents distort mapping
How does pre-substorm energy storage result in:
Auroral intensification, Equatorward motion?
Results may change our concepts of flux circulation, tail stability, MI coupling

11. Data availability