RELATION BETWEEN RING CURRENT, IONOSPHERE AND PLASMASPHERE

1
RELATION BETWEEN RING CURRENT, IONOSPHERE AND
PLASMASPHERE

• P. C. Brandt

2
KEY EFFORTS

• John Foster
• Phil C. Anderson
• Jerry Goldstein
• Mei-Ching Fok and Y. Ebihara
• R. A. Wolf
• T. Immel

3
E-FIELD OF THE INNER MAGNETOSPHERE
CONVECTION COROTATION
SELF-CONSISTENT
SUB-AURORAL E-FIELD
4

• How and when is the sub-auroral electric field
  formed?

5
REGION 1
REGION 2
EXTENDING TO PLASMASHEET
6
HOW AND WHEN?

• Duskside R2-FAC close poleward through
  low-conductance gap
• Significant E-fields
• Moderate R2-FAC

AURORAL OVAL
LOW CONDUCTANCE
7
TEST
I integrated region 2 FAC (Iridium) U
Sub-auroral potential drop (DMSP) R Resistance
between Region 2 and Region 1 RconstD,
Dseparation ? U/(DI)constant?
I
R
U
8
CURRENT
ALL IRIDIUM DATA FROM H. KORTH AND B. J. ANDERSON.
9
RELATION TO RING CURRENT

• Proton pressures from HENA ? Current
• Underestimating
• 10 min resolution

10
SUB-AURORAL POTENTIAL
ALL DMSP DATA PROVIDED BY P. C. ANDERSON
11
SEPARATION?
MLAT1 EQUATORWARD EDGE OF OVAL MLAT2 90
VALUE OF SAPD
MLAT2
I
D
D
R
MLAT1
U
12
I VERSUS U
13
D VERSUS U
14
DI VERSUS U
15

• How does the sub-auroral E-field affect the inner
  magnetosphere?

16

• PLASMASPHERE

17
UNDULATION
Courtesy of J. Goldstein
18
SUB-AURORAL E-FIELD?
HENA CURRENTX 70
IRIDIUM CURRENT
SEPARATION
POTENTIAL
1936 UT UNDULATION
1900 UT AURORAL ONSET
19
SUMMARY

• Sub-auroral E-field depends more on size of
  low-conductance gap, than FAC intensity.
• Expected for a low-conductance gap
• Sub-auroral field modifies E-field of inner
  magnetosphere

20

• EQUATOR?

21
EQUATORIAL FOUNTAIN
E-FIELDS LIFT PLASMA ACROSS B-FIELD
NEUTRAL WINDS FROM SUB-SOLAR POINT
22
IONOSPHERIC BUBBLES
DRIFT
BUBBLE
23
DRIFT VERSUS DST

• Eastward drift correlates with Dst.
• Outward or poleward E-field required to brake
  drift.
• Two possibilities
• Direct high-latitude electric field effects.
• Reversal of thermospheric neutral wind, through
  high latitude heating.

Fejer et al., 1993
Immel et al., JGR, submitted, 2003.
24
CLUSTER-IMAGE
25
(No Transcript)