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Recent KTH Cluster research. T. Karlsson, A. Collier, T. Johansson, S. Liléo (Figueiredo), G. Marklund, m. fl. C4. m. n. L = 4.6 MLT = 02:43. Pi2 pulsations within plasmasphere 2003-01-21. Andrew Collier, KTH and Univ. Of KwaZulu-Natal, Durban. Poynting Flux, P. C4. P. m. n.

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Recent KTH Cluster research

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Recent kth cluster research

Recent KTH Cluster research

T. Karlsson, A. Collier, T. Johansson, S. Liléo (Figueiredo), G. Marklund, m. fl.


Recent kth cluster research

C4

m

n

L = 4.6 MLT = 02:43

Pi2 pulsations within plasmasphere2003-01-21

Andrew Collier, KTH and Univ. Of KwaZulu-Natal, Durban


Recent kth cluster research

Poynting Flux, P

C4

P

m

n

L = 4.6 MLT = 02:43

CONCLUSIONS

1. Phase shift 90 between E and B, indicative of standing wave in radial direction – cavity resonance

2. Poynting vector indicates energy flow in azimuthal direction, possibly indicating open-ended cavity.


Recent kth cluster research

s/c 1

s/c 2 +16’30’’

s/c 4 + 39’30’’

s/c 3 + 57’

35'

35'

j//up event 1

Cluster results

temporal / spatial evolution

of discrete auroral arcs

Figueiredo et al., AG, 2005

Temporal Evolution

Symmetric

U-shaped

potential

j//

V= ∫ E^·ds

LS Inverted-V

arc

LS Inv-V

arc

arc

V= ∫ E^ · ds

merging together

intensifying

PSBL CPS

PSBL CPS PSBL CPS

Cluster s/c 1 obs 030501

Upward 10 keV

O+-beam

GM050825

1keV

e- ↓

V

(kV)

0

-10

820

E

(mV/m)

0

3

j//

(mA/m2)

0

O+

1-10

keV

O+

10-38

keV

↑O+

0'

45'

15'

30'


Recent kth cluster research

DMSP image

surge

DMSP

Cluster

surge horn

surge horn

poleward

expansion

0.5 km/s

Cluster s/c

Cluster results

j//upevent 2

temp / spatial evolution

of discrete auroral arcs

Cluster observations 030503

V= ∫ E^ · ds j//

surge horn

multiple arcs

merging

together

& intensifying

PC PS

PC PS

GM050825

South Pole ASI images

s/c 1

5

kV

10

mA/m2

s/c 2 — +7’

s/c 4 — +22’

20'

20'


Recent kth cluster research

Evolution of pos & neg U-shaped potentials in two connected FAC branches

Marklund et al, 2006

s/c 1

s/c 3

s/c 2

s/c 4

acc ions

14 FEB 2001 EVENT SUMMARY

· bipolar, div E-field » 1.7 V/m

· PSBL / CPS boundary & Ne-grad

· scale size of 8 km

· DF^,increases from » 0.4to 2.7 kV in 100 s

· DF// in jllup» - DF^ in jlldown

· Local Ne-min & E-region Ne-hole

· downward FAC » 10 µA/m2

DF//decreases

from 3 kVto 1 kV

acc electrons

conv E-field

DF^ = ∫ E^ ·ds increases from

0.4 kVto3 kV

s/c 1

s/c 3

s/c 2

s/c 4

»

div E-field

·

·

Ne-hole

black aurora

aurora

t = 100 s

t = 0 s

t = 200s

t=300s

Auroral current circuit

GM050825


Recent kth cluster research

Cluster data

j//down event 2

evolution of div E-field structures

div E^

Bt

EN

Bt

EN

div E ^ = 0.3 V/m

-Vs/c

V

-Vs/c

V

EFW

FGM

data

PSBL CPS

PSBL CPS

up FAC

down FAC

up FAC

down FAC

div E ^= 1.7 V/m

Bt

EN

div E ^

Bt

EN

-Vs/c

V

-Vs/c

V

PSBL CPS

up FAC

down FAC

PSBL CPS

up FAC

down FAC

Marklund et al, 2006

GM050825


Recent kth cluster research

5. Evolution of U+-potential: Simulation of Event 1

Jll

ENS

equator

L= 8.25

Cut along Cluster track

L= 7.25

s. iono-

sphere

ENS

Jll

Cluster track

cross-section

Streltsov and Marklund, acc for JGR, 2006


Recent kth cluster research

Where do monopolar and bipolar E-fields occur with respect to boundaries ?

Statistical study of bi- & monopolar E-field events

Johansson et al, accepted Ann. Geophys. 2006

Equatorward, monopolar E-fields, are found at the PC boundary in the evening LT sector

PC

PSBL

CPS

Interpretation

Bipolar E-fields are found at

particle boundaries within PS

(Marklund et al, 2004)

Bipolar

Monopolar fields, if plasma,

dense enough to support

connecting FACs, exists on

one side of the boundary only

Bipolar fields, if plasma,

dense enough to support

connecting FACs, exists on both sides of the boundary

GM050825


Recent kth cluster research

beta

bipolar

┴ potential

monopolar

Eeast

Eequator

Johansson et al., accepted Ann. Geophysicae, 2006


Recent kth cluster research

Auroral potential and associated FAC reconfiguration

during thinning of the PSBL

Marklund et al, subm to JGR, 2006

t = t0

t = t0 + 16 min


Recent kth cluster research

Auroral potential reconfiguration: Cluster observations

Cluster s/c 1 t= t0

Cluster s/c 2t = t0 + 16 min

PEACE

electron

data

^

CPS

CPS

PSBL

PSBL

F^

F^

EFW &

FGM data

Potential step

-Vs/c

-Vs/c

Potential well

Es

Es

BT

monopolar

E-field

BT

Bipolar E-field

FAC

FAC


Auroral scale sizes ongoing

Auroral scale sizes (ongoing)

5 km

5 km

#

#

S(n)

  • Which are the characteristic scale sizes of E, FAC, Δn and how are they related to mono/conv/div E, ΔV, Kp, ΣP…. ?

  • >1000 events

S(E)

2 km

4 km

#

#

S(FAC)

gyroradius

Johansson et al.


Recent kth cluster research

Expected correlation with constant ionospheric conductivity and no E// :

En

Bt

High-altitude signatures of ionospheric density depletions

T. Karlsson et al.

Instead sometimes, correlation [downward j// ] ~ En

2005-05-19, SH, MLT ~ 20

j//(mA/m2)

En(mV/m)

upward current

downward current

t (s)


Recent kth cluster research

Jn

S

En

Model – ionospheric modification by downward FACs

From earlier simulations

j//

Magnetosphere

upward j//

downward j//

Ionosphere


Recent kth cluster research

j//

j//

SP

SP

En

En

DBt

DBt

2002-04-27

2005-01-11


Recent kth cluster research

Expected correlation with constant ionospheric conductivity and no E// :

Instead sometimes, correlation [downward j// ] ~ En

2005-05-19, SH, MLT ~ 20

En

j//(mA/m2)

En(mV/m)

upward current

Bt

downward current

t (s)

High-altitude signatures of ionospheric density depletions

T. Karlsson et al.


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