PRESSURE, CURRENTS AND ELECTRIC FIELDS IN THE INNER MAGNETOSPHERE

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PRESSURE, CURRENTS AND ELECTRIC FIELDS IN THE
INNER MAGNETOSPHERE

• Pontus Cson Brandt, D. G. Mitchell, S. Ohtani,
  E. C. Roelof, R. Demajistre JHUAPL, MD
• J. Goldstein, R. A. Wolf Rice, TX
• M. C. Fok NASA GSFC, MD
• A. Ridley, M. Liemohn U. Michigan

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Dipole validity
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(No Transcript)
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IONS ? CURRENT
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Field aligned currents (FAC)(Region 2 system)
HENA
IRIDIUM (Courtesy Dr. B. Anderson, JHUAPL)
Micro A/m2
-0.91
-0.1
0.1
0.91
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R1 HIGH CONDUCTIVITY R2 LOW CONDUCTIVITY Sp
HIGH, SH LOW ? NORTHWARD E-FIELDS WE THINK.
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RING CURRENT AND E-FIELDS(RidleyLiemohn 2002)
50 closure through ionosphere
Weak ring current closure
Strong E-field (SAPS?)
Weak radial E-field
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MAGNETOSPHERIC EFFECTS

• Eastward rotation of main phase ring current
• Plasmaspheric erosion?

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MODELING CRCM (M. C. Fok et al., JGR, 2001)
WITH SELF- CONSISTENT E-FIELD
WITHOUT SELF- CONSISTENT E-FIELD
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Electric fields
The Comprehensive Ring Current Model (CRCM) Fok
et al., 2001 computes the E-field
self-consistently via the closure through the
ionosphere. Matches HENA observations.
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DYNAMICS OF E-FIELD

• PLASMASPHERE EROSION
• Plasmasphere responds to changes in E-field via
  ExB drift ? EmV/m Goldstein et al., GRL, 2002.
• E-field enhancement delayed 30 min from IMF
  southward turning Jerry Goldstein.

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10 JULY 2000
0515 UT Substorm 0638 UT SW-pressure pulse
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2 JUNE 2001
0052 UT NO substorm, NO compression, PRC
pressure increase 10 min before erosion. 0354
UT Substorm
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MECHANISM(see Jerry GRL submitted)

• Clearly, the plasmasphere responds to some strong
  E-fields. What are those?
• Increase and penetration of convection E-field
  (30 min)
• Or, is the erosion direct response of
• Disruption of the shielding due to magnetospheric
  compression Wolf, 1982.
• Induced E-field due to substorm
• Pressure build-up of PRC?FAC R2 increase?radial
  E-field increase at inner edge.?ExB transports
  plasmasphere material westward?