Cold, keV, & MeV ion signatures of westward moving auroral bulge at L=4 in equatorial plane

Cold, keV, & MeV ion signatures of westward moving auroral

bulge at L=4 in equatorial plane

M. Yamauchi1, I. Dandouras2, P.W. Daly3, H. Frey4, P.-A. Lindquvist5, G. Stenberg6, Y. Ebihara7, R. Lundin1, H. Nilsson1, H. Reme2, M. Andre6, E. Kronberg3, and A. Balogh8

(1) IRF, Kiruna, Sweden, (2) CESR, Toulouse, France, (3) MPS, Katlenburg-Lindau, Germany, (4) UCB/SSL, Berkeley, CA, USA, (5) Alfven Lab., KTH, Stockholm, Sweden, (6) IRF, Uppsala, Sweden, (7) IAR, Nagoya U., Nagoya, Japan, (8) Blackett Lab., ICL, London, UK

ICS-9, Graz, 2008-5 / revised for IMC-workshop, Espoo, 2008-7

25 minH+

O+

H+

He+

0.01~40 keV

102 keV

MeV

Clusterperigee(19 MLT, R≈4 RE, Z=0 RE)

90 minoverview

Z=0 Re, R=4 Re

What do these events indicate?From 06:43 UT event(a) Composition of cold plasma plasmasphere-magnetosphere coupling in the inner magnetosphere.

(b) Mass-dependent filling of medium-energy ring current ions (and by auroral bulge?) drift motion

(c) Propagation of large DC electric field in the equatorial plane.

(d) Inter-SC difference of energetics non-gyrotropic

From 06:48 UT event (not today)(d) Bi-parallel beams in the equatoral plane

(e) Equatorial signature of the transpolar arc.

* Near equator (Z ≈ 0 RE)* Perigee (R ≈ 4 RE)

Spacecraft

SC1-SC4 ≈ 25 sec

SC1-SC3 ≈ 1 min

* 19 MLT

S/C

north

south

dawndusk

sun

tailU

E

IMAGE/FUV 06:26~06:56 UT

06:26 UT

06:28 UT

06:30 UT

06:32 UT

06:34 UTS/C

06:36 UT

06:38 UT

06:40 UT

06:42 UT

06:44 UT

06:46 UT

06:48 UT

06:50

06:52

06:54

06:56


06:26 UT

06:28 UT

06:30 UT

06:32 UT

06:34 UTS/C

06:36 UT

06:38 UT

06:40 UT

06:42 UT

06:44 UT

06:46 UT

06:48 UT

06:50

06:52

06:54

06:56

~06:43 event


06:26 UT

06:28 UT

06:30 UT

06:32 UT

06:34 UTS/C

06:36 UT

06:38 UT

06:40 UT

06:42 UT

06:44 UT

06:46 UT

06:48 UT

06:50

06:52

06:54

06:56

~06:43 event ~06:48 event

~06:26 UT: minor substorm~06:38 UT: new glowing MCQ = Cluster conjugate

#1 #2

Observation of 06:43 UT (#1) event1. Sudden change in particle flux (> 40 keV, > 10 keV,

and < 100 eV) when aurora bulge arrived Cluster’s conjugate ~19 MLT.

2. Change is simultaneous at all SC (SC-3 leading by 1~10 sec).

3. Simultaneous DC field change (tailward E~8mV/m, Pi2-like rarefaction |B|≈|BZ| up to 20%) without special wave activity.

4. Increase in medium energy (~100 keV, mass dependent) ion flux. Diamagnetic effect by ∆PP can quantitatively explain ∆PB.

5. Decrease in energetic e- (>30 keV) and ions (> 0.1 MeV)

6. Temporal (about 1 min) change of pitch-angle of 10-40 keV to more field-aligned than perpendicular.

7. Bulk motion of cold He+ and H+ (no cold O+ or He++). The ion velocity (20km/s, duskward) agrees with the ExB velocity.

25 minH+

O+

H+

He+

0.01~40 keV

102 keV

MeV

Clusterperigee(19 MLT, R≈4 RE, Z=0 RE)

90 minoverview

Z=0 Re, R=4 Re

keV ions of ionospheric origin?

No mass-energy dispersionBi-directional

= not auroral ions

06:43 UT 06:43 UT

//

//

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Observation of 06:43 UT (#1) event1. Sudden change in particle flux (> 40 keV, > 10 keV, and < 100

eV) when aurora bulge arrived Cluster’s conjugate ~19 MLT.







Sudden change in ion and field06:48:3006:43:00

06:48:30

60s behind

25s behind

leading

06:43:00Timing (ion = 12sec resolution)

Timing (E-field)

3 min

Timing (B-field)

increase in 101~2 keV ion flux

decrease in 102~3 keV ion flux

H+ < 90 keV

H+ > 160 keV

increase in 101~2 keV ion flux

decrease in 102~3 keV ion flux

He < 350 keV

He > 700 keV

O < 0.9 MeV

O > 1.4 MeV

increase-decrease combination

First increase, then decrease

keV ion increase is NOT mass dependent

No mass-energy dispersion (2~10 keV)

06:43 UT

Decrease in > 40 keV electron flux

e- > 40 keV

cf. some decrease in < 30 keV ions

Change in PA distirbution

06:48:3006:43

Composition

0643 0644 0645 0646 0647 0648 0649

06:44:00 UT 06:48:30 UT

H+

He++

He+

O+

contamination

(2) TOF mass analyser: He+ rich

No oxygen!

He+ convection ExB velocity

ExB drift velocity = 25~50 km/s4-15 eV for H+

=> 15-60 eV for He+60-250 eV for O+

Detail on Ion dynamics

(spin)Cold ion moving in one (perpendicular) direction

15-60 eV for He+

4-15 eV for H+

Ion drift direction vs E

X (sunward)

Y (duskward)

//

drift direction

- UxB (estimated E) direction

U ≈ -ExB in direction (but no guarantee of frozen-in

Observation Summary (06:43 UT)1. Sudden change in particle flux (>40 keV, >10 keV, and <100








Indications (conclusion)E-field propagates together with the auroral bulge

at ground, which is in the same direction as convection direction.

cold He+ flux >> cold O+ flux: plasmaspheric He+ at 4 RE.

No local acceleration: Mass dependent drift ? How did they come on time?

Large-scale configuration change: pseudo-onset?

Energy source? / Can minor auroral activity produce ring current ions?

ion-scale ?All SC should observe the same behavior of ions if ion gyro-radius (RB = mv/qB) >> inter-S/C distance

RB for B ≈ 200 nT condition

10 keV 100 keV 1 MeV

H+ v = 1400 km/s

RB = 70 km

v = 4000 km/s

RB = 200 km

v = 14000 km/s

RB = 700 km

He+ v = 700 km/s

RB = 140 km

v = 2000 km/s

RB = 400 km

v = 7000 km/s

RB = 1400 km

O+ v = 350 km/s

RB = 300 km

v = 1000 km/s

RB = 800 km

v = 3500 km/s

RB = 3000 km

consolation

S/C distance ≈ 100 km in z direction & 50 km in x-y direction

≈ RB for 10~20 keV H+ << RB for Ring current ions

H+ > 20 keV (O+ > 2 keV) should behave the same at all SCs if the gyrotropic assumption is correct

But, there is inter-SC difference

RAPID (SSD) data

Inter-SC difference: trapped H+ for CIS

For flux increase: (1) SC-2 < SC-1 < SC4=SC3

H+: 80~160 keVHe+: 200~300 keV

(2) SC-2 > SC-1 > SC4=SC3H+: ~60 keV O+: 500~600 keV

For flux decrease: (3) SC-2 < SC-1 < SC4=SC2

He+: 400~700 keV(4) SC-2 > SC-1 > SC4=SC3

O+: ~400 keV

inter-SC difference !

Hybrid: (5) SC-2 > SC-1 > SC4 > SC3

O+: 400~500 keV

Look at more carefully: energy dispersion

Energy dispersion = magnetic drift? or shell shift?

End

Now is the time to analyse/simulate Inter-SC difference of energetic particles with

ion gyro-radius (RB) >> inter-S/C distance

next is 06:48 event


06:26 UT

06:28 UT

06:30 UT

06:32 UT

06:34 UTS/C

06:36 UT

06:38 UT

06:40 UT

06:42 UT

06:44 UT

06:46 UT

06:48 UT

06:50

06:52

06:54

06:56

~06:43 event ~06:48 event

All info

ET

PA

O+ 30~500 eVETPA

ET

PA

25~150 eV

5-25 eV

25~150 eV

5-25 eV

25~150 eV

5-25 eV

25~150 eV

5-25 eV

all at 06:48:30 UT (12s resolution)SC-1: leading

SC-3: 60s behind SC-1

SC-4: 25s behind SC-1

0642 0644 0646 0648 0650 0652 0654 0656

Observation of event #21. Simultaneous at SC-1, 4 and -3 within 1 sec sudden

activation

2. Bi-directional along B, and DC E-field disturbance double parallel potential is carried by convection?

3. Wave with randomly changing Pointing flux direction (not shown here) wave is caused by the bi-parallel beam

4. Decrease 5~70 keV large-scale configuration change

5. More O+ than He+ not from cold plasma

6. Filamentation in the transpolar arc but, the relation is not clear (?)

7. Only minor magnetospheric activity Why do we observed only once in 5 years ?

no wave@06:43 UT, wave@06:48 UT

ion

dE

dB

S//

E/B

dBZ

dBXstagnant

BB-EM

spin effects

150 nT ΩP = 4 Hz

ΩHe?

energetic component

change: < 70 keV only

Composition from energy ratio(1) From energy peak: plasmaspheric He+ rich

= 0°

= 180°

= 360°

10 100 [eV] 10 100 [eV]

Precursor (06:44 UT) Heating (06:49 UT)

H+ He+ O+

ratio=4: O+/He+ or He+/H+

18eV 70eVH+ He+

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SC location* Near equator (Z ≈ 0 RE)* Perigee (R ≈ 4 RE)* 19 MLT* Short distance (mainly in Z direction) SC1-SC4 ≈ 25 sec SC1-SC3 ≈ 1 min

SC

mot

ion

SC

mot

ion

SC motion

Ground conj.

06:43 06:48

Nothing special

only 50 nT activity

Cold, keV, & MeV ion signatures of westward moving auroral bulge at L=4 in equatorial plane

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