Dynamics of reconnection and multiple activation of substorms

Study X-line signatures and examine their relationship to substorm development

-Current sheet observations• Jan. 09, 2008 ~ 700 UT event• Feb.16, 2008 ~ 220 UT event

-Remote sensing• Feb.10, 2008 425UT, 545 UT event

2008/02/26 Rumi Nakamura (IWF/OEAW)

Major conjunction~0700UT AE ~400 nTWith multiple activations

Thinning CSTHB: lobe PSBLPS I: BY increase II: Bz - Bz +

THC: PSBL lobe PS I: BY increase, Bx decrease short dBz>0 while Bz decrease II: Bz - +

THD, THE: two dipolarizations I: 654 UT THE THD II: 722 UT THD, THE

Tailward evolution of X-line

Dipolarization I II

DATA QUESTION?

For reconnection current sheet,Determine flow reversal is useful

How far can we use ESA,SSTmoments. Looks SST portionimportant. What should we do ?

DATA QUESTION?

BBF-like signatures observed at D and E with differences(interesting to compare for these two different activations)

THD THE

SST moment is important!?

20080109 07UT event summary• Modest substorm with multiple activations

(AE 400 nT) • Bz reversal (flow reversal?) observed by B and C

with time difference motion/evolution of Xline. • Two dipolarizations observed by D-E

I. during current sheet thinning at C and B

II. associated with X-line at C (and B)

Plan: Confirm X-line signatures with particle/field data, compare flow evolution for I. II.

centered high-lat. (Rank) or Greenland(?, tbd)

Minor conjunction0220 UT - AE ~250 nT

Dipolarization I II

THC: PSBLPS I: negative Bz tailward of Xline II: postive Bz earthward of X line

THD, THE : dipolarizationI: ~220 UTII:~0244 UT

Bz reversal around IITwo X-line activations rather than in-site Xline observation?

DATA QUESTION?

For studying reconnection current sheet, determine flow reversal timing is very important

Similar to 20080109 event,SST seems to show reversal...How far can we use ESA,SSTMoments?Recommendation ?

Like 20080109 eventTHEMIS D and E have alsosimilar issue

DATA QUESTION?Similar to 20080109 eventBBF-like signatures observed at D and E with differences(interesting to compare for these two different activations)

SST moment is important!?

20080216 0220UT event summary• Small activation (high-lat.) (AE ~250 nT) • +Bz and –Bz enhancement (or Bz reversal)

observed by C associated with two dipolarization event (D, E) and ground-based activation. Different activation of X-line(s?) at different location (first Earthward then tailward side of C)

• Plan: Confirm X-line signatures with particle/field data (Timing of flow reversal essential) Compare flow evolution for I. II.

Two small activationscentered high-lat. (Rank) or Greenland(?, tbd)

Major conjunction0430UT AE ~200 nT0540UT AE ~350 nT

THB: Tail lobe Bz + -

THC: lobe/PSBL Bz - + 1 flux rope, 2 TCR

D, E: expansion of plasma sheet

Remote X-line sensing between C and B

DATA QUESTION?

THB

THD

THE

Relationship between earthward motion of flux ropeand innermagnetospheric signatures could be studied

Is this taiward flow OK ?

The spectra around0552-55 UT may look dark region at two place?(multi composition ?)

Tailward motion or two of very weak TCR ?

THB: lobe Bx - , Bz - THC: lobe Bx + , Bz -

20080210 0430-0550 UT event summary

• Two modest activations (200, 350 nT) • Lobe/PSBL signatures may allow to remote-

sensing the X-line• Plan: Using transient reconnection model

(Semenov et al., 2007) to model location/motion of X line, temporal change of reconnection rate (by Stefan Kiehas)

• .. We are still on search of this kind of event...