Spring AGU Conference 1 05/27/2008

• Introduction, THEMIS overview– Overview of orbits

• First THEMIS tail results from 2008– Westward expansion

– Typical signatures at 20-30Re• Local time effects

• Neutral sheet proximity

• History of tail activity

• Simultaneity of tail phenomena– The first few minutes

– Rapid M-I coupling

THEMIS Observations from the First tail season

Spring AGU Conference 2 05/27/2008

Maximizing Substorm Science on THEMIS:Probe Alignments and Ground Conjunctions

Vassilis Angelopoulos,UCLA ESS April 13, 2006

Simulation: J. Raeder, UNH

Visualization: Tom Bridgman,GSFC/SVS

Spring AGU Conference 3 05/27/2008

Launch=2007-02-17

2007-03-23

2007-06-03

2007-07-15

2007-08-30

2007-12-04

XGSE

YGSE

TH-B

TH-C

TH-D

TH-E

TH-A

P1

P2

P3

P4

P5

First 10 months

Angelopoulos, 2008Space Sci. Rev.In Presshttp://themis.ssl.berkeley.edu/

Spring AGU Conference 4 05/27/2008

Tail 12008-02-02

Dayside 12008-08-08

XGSE

YGSE

TH-B

TH-C

TH-D

TH-E

TH-A

P1

P2

P3

P4

P5

First year baseline orbit

Angelopoulos, 2008Space Sci. Rev.In Press

Spring AGU Conference 5 05/27/2008

TH-C

DBA

E

Ygse

Xgse

D

B

A

2000kmTH-C

DBA

E

Ygse

Xgse

D

B

A

2000km

D

B

A

2000km

Angelopoulos et al., First Results from THEMIS, SSR, 2008Raeder et al., Open GGCM simulations for ..THEMIS…, SSR, 2008Keiling et al., Correlation of substorm injections…, GRL, 2008Keiling et al., Multiple intensifications inside the … bulge…, JGR, submitted 2008

V ~

350

km/s

First light: Nature’s welcome.Substorm captured on March 23, 2007

Speed: 1MLT/min

Spring AGU Conference 6 05/27/2008

Westward expansion speed on the ground ~ 1 MLT hrs/minMaps to 10RE as 200-300km/s westward

Westward observed speed in space (D - E) is ~250km/sConsistent with mapping the speed from the ground up

Summary: First Observations of Westward Traveling Surge in Space

Similar papers establish the nature of substorm expansion in space:

Zhang, H. et al., JGR, 2008 [February 28, 2007 substorm; FGM only]

Donovan, H., et al., GRL, 2008 [March 13, 2007 substorm; TH-A ESA]

In 2009-2012 THEMIS probes will again be at 1000-3000km in the plasma sheetWill map over Siberia/Alaska and Greenland/Iceland/ScandinaviaExpect to do microphysics of current disruption and study field aligned current generation

Conclusions on March 23, 2007 event

Spring AGU Conference 7 05/27/2008

2008 tail season

Feb-14Feb-10

Feb-6Feb-2

Feb-18 Feb-22 Feb-26Midnight Pre-midnight

Jan-29

Feb-26

Jan-29

Mar-01

Spring AGU Conference 8 05/27/2008

-200

-100

0

100

07:00 07:30 08:00 08:30 09:00

2008 January 29

0714 0738

0831

AU, AL

XGSM

YGSM

10 RE

10 RE

–30 RE

P1(B)P2(C)P3(D)

P4(E)P5(A)

Jan 29, 2008 substorms07:14 UT onset/precursor? 07:38 UT onset08:31 UT intensification

Spring AGU Conference 9 05/27/2008

-200

-100

0

100

07:00 07:30 08:00 08:30 09:00

2008 January 29

0714 0738

0831

AU, AL

P5(A)

Too far West for all onsets (1-2RE)

XGSM

YGSM

10 RE

10 RE

–30 RE

P1(B)P2(C)P3(D)

P4(E)P5(A)

Jan 29, 2008 substorm

Spring AGU Conference 10 05/27/2008

P4(E)

Jan 29, 2008 substorm

-200

-100

0

100

07:00 07:30 08:00 08:30 09:00

2008 January 29

0714 0738

0831

AU, AL

Near 1st onsetEast of 2nd and 3rd onsets (1RE)

XGSM

YGSM

10 RE

10 RE

–30 RE

P1(B)P2(C)P3(D)

P4(E)P5(A)

Spring AGU Conference 11 05/27/2008

-200

-100

0

100

07:00 07:30 08:00 08:30 09:00

2008 January 29

0714 0738

0831

AU, AL

P3(D)

Right-on for 1st onsetEast of 2nd and 3rd onsets (1RE)Each onset preconditions (relaxes) tail

XGSM

YGSM

10 RE

10 RE

–30 RE

P1(B)P2(C)P3(D)

P4(E)P5(A)

Jan 29, 2008 substorm

Spring AGU Conference 12 05/27/2008

XGSM

YGSM

10 RE

10 RE

–30 RE

P1(B)P2(C)P3(D)

P4(E)P5(A)

-200

-100

0

100

07:00 07:30 08:00 08:30 09:00

2008 January 29

0714 0738

0831

AU, AL

P2(C)

At right MLT but at outer plasma sheetSouth turning during 1st onset (Rx?)

Within ~1min from onset South-then-North turning during 2nd

Only Northward turning during 3rd Dipolarization/CD moves tailward

Jan 29, 2008 substorm

Spring AGU Conference 13 05/27/2008

-200

-100

0

100

07:00 07:30 08:00 08:30 09:00

2008 January 29

0714 0738

0831

AU, AL

P1(B)

XGSM

YGSM

10 RE

10 RE

–30 RE

P1(B)P2(C)P3(D)

P4(E)P5(A)

At right MLT but at PSBL/LobeSouth turning during 1st onset (Rx?)

Within ~1min from onset South-then-North turning during 2nd

Only Northward turning during 3rd onsetExpansion/Dipolarization/CD moves tailward

Jan 29, 2008 substorm

Spring AGU Conference 14 05/27/2008

• January 29, 7-8 UT substorms (P1,2 Zns~3-5RE)– Localization in Y demands good space-ground mapping

• Within 1RE or better in space, within <5o in the ionosphere

– Substorms are sequences of activations:• Precursor, main onset, intensification• Each activation preconditions the tail sector within which it occurred

– At 10-12RE, all activations at onset meridian have Northward field/Earthward flows– At 15-20RE, initial activations accompanied by Southward – then Northward field

• Subsequent activations accompanied by Northward field/Earthward flows

– At 20-30RE, initial activations accompanied by Southward, or bipolar field• No flows or beams if away from the neutral sheet even if at the plasma sheet boundary

– If at the right meridian, P1, P2 show clear signatures within ~1min of onset• Weak signatures of fast flows, no intense beams away from the neutral sheet• If anything is happening to the plasma it is probably happening closer to the neutral sheet

Event summary: Jan 29

Spring AGU Conference 15 05/27/2008

Mar 1, 2008 substorms01:48:52 UT precursor? 01:54:30 UT onset

01:48:52UT

01:54:30UT

Spring AGU Conference 16 05/27/2008

Signatures seen at TH-C (P2) first…… then at TH-B (P1)

Bipolar Bz (+/-)Tailward flows

1st event: FAC (By) at P3, P4At large distance from a thin CSField aligned current below

2nd event: ExpansionAccompanied by FACNo sharp dipolarization

Spring AGU Conference 17 05/27/2008

• Mar 01, 01:48:52UT, 01:54:30UT onsets (See: Runov, A. et al JGR)

– P1, P2 at 0. 5RE from nominal neutral sheet– At 17-23RE, onsets accompanied by tailward flows, southward fields

• Flows started inside of TH-C (P2, < 17RE) first, then moved to TH-B (P1, at 23RE)• Tailward beams seen at TH-C ahead of flows

– Flows (and energetic particles at TH-C (P2) – not shown) within 1 min from onset

– P3, P4 at 1RE from nominal neutral sheet• Far from an extremely thin neutral sheet• Observe FAC below satellite during 1st event• Observe FAC during plasma sheet recovery during 2nd event

Event summary: Mar 1

Spring AGU Conference 18 05/27/2008

• Substorms have lived up to their notoriety: tough to crack– Start from localized (1RE scale), expand azimuthally and tailward– Start deep inside a thin plasma sheet near an extremely thin current sheet

• Azimuthal expansion of WTS can be tracked in space shown to match ground• Must select events when probes are both in right Y and Z location

• THEMIS observed classical substorm signatures at all altitudes, but:– Signatures are seen near-simultaneously at multiple altitudes– When at right meridian, all probes respond to ~1 min of ground onset– Response varies with substorm history:

• Earliest onset (pseudobreakup, precursor, small substorm or onset) has:– At 20-30RE:

» Southward Bz consistent with tailward moving plasmoid when Zns > 2-3RE

» Tailward beams or flows when Zns < 1RE from nominal neutral sheet– At 10-20RE: Northward Bz consistent with Earthward moving flux rope

» Field aligned current signatures when Zns > 2-3RE

» Fast Earthward flows when Zns < 2RE

• Follow-on onsets (2nd, 3rd) have:– Earthward flows seen further down the tail near (~1min) of onset– Dipolarization and plasma sheet expansion accompany them

• The 1min scale response is shorter than typical Alfvén transit times– Only electrons can provide fast coupling– May be excited by a kinetic Aflvénic pulse but run ahead of waves

THEMIS Summary