ON THE RELATION BETWEEN RING CURRENT, IONOSPHERE AND PLASMASPHERE

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ON THE RELATION BETWEEN RING CURRENT, IONOSPHERE
AND PLASMASPHERE

• P. C. Brandt
• Acknowledgements P. C. Anderson, J. Goldstein,
  H. Korth, B. J. Anderson, R. DeMajistre, T. J.
  Immel, C. Vallat

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KEY EFFORTS

• Phil C. Anderson Sub-auroral potential drop from
  DMSP/IDM
• Jerry Goldstein Plasmaspheric response
• Mei-Ching Fok, Y. Ebihara, R. A. Wolf
  Self-consistent ring current modeling.
• T. J. Immel Low-latitude ionospheric effects
  (bubble drift speed).

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E-FIELD OF THE INNER MAGNETOSPHERE
CONVECTION COROTATION
SELF-CONSISTENT
SUB-AURORAL E-FIELD
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• How and when is the sub-auroral electric field
  formed?

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REGION 1
REGION 2
EXTENDING TO PLASMASHEET
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HOW AND WHEN?

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

AURORAL OVAL
LOW CONDUCTANCE
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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
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ICURRENT
ALL IRIDIUM DATA FROM H. KORTH AND B. J. ANDERSON.
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RELATION TO RING CURRENT
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RELATION TO RING CURRENT

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

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UPOTENTIAL
ALL DMSP DATA PROVIDED BY P. C. ANDERSON
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DSEPARATION
MLAT1 EQUATORWARD EDGE OF OVAL MLAT2 90
VALUE OF SAPD
MLAT2
I
D
D
R
MLAT1
U
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I VERSUS U
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D VERSUS U
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DI VERSUS U
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• How does the sub-auroral E-field affect the inner
  magnetosphere?

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• PLASMASPHERE

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

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• EQUATOR?

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EQUATORIAL FOUNTAIN
E-FIELDS LIFT PLASMA ACROSS B-FIELD
NEUTRAL WINDS FROM SUB-SOLAR POINT
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IONOSPHERIC BUBBLES
DRIFT
BUBBLE
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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.
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CLUSTER-IMAGE
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