HENA: IMPLICATIONS FOR STRONG E-FEILDS (and some more...)

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HENA IMPLICATIONS FOR STRONG E-FEILDS(and some
more...)
P. Cson Brandt, D. G. Mitchell, R. Demajistre,
E. C. Roelof The Johns Hopkins University Applied
Physics Laboratory
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OUTLINE
E-FIELD DURING MAINPHASES 1. Storm mainphases
HENA observes peak at post-midnight. 2.
Comparison with models M. -C. Fok. 3. Why? M.
Liemohn STORM-SUBSTORM UPDATE GLOBAL SAWTOOTH
OSCILLATIONS R. Skoug
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DIFFERENCES

• COMPARISON WITH WEIMER MODEL (FOK)
• Peak of ion distribution is skewed in MLT 16-200
  keV.
• Peak is slightly further in.
• Configuration appears less sensitive to
  disturbances.
• Skewing appears to increase with epsilon
  parameter of IMF.

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WHY NOT SKEWING?
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CONCLUSIONS

• The E-field of the inner magnetosphere are skewed
  during storm mainphases.
• Possibly due to the additional ring-current
  driven potentials Liemohn.
• One would expect the skewing to be established as
  the partial ring current develops...
• ...or...counter example 21 Oct 2001.

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STORM-SUBSTORM

• Substorms in the 4 Oct 2000 mainphase appear as
  "ripples on the surface".
• 4 Oct 2000, 21 Oct 2001 Substorms seems to
  appear at the beginning of storms What are their
  role inestablishing the first partial ring
  current?

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GLOBAL SAWTOOTH OSCILLATIONS???

• Ruth Skoug will talk more.
• Global dipolarization events are sometimes
  observed during storm mainphase.
• HENA can confirm that ion distributions are
  enhanced during 20 min, GLOBALLY!
• What is going on???
• MOVIE 11 Aug 2000.

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SUMMARY

• How is the skewed E-field formed?
• Are substorms "ripples on the surface" during
  magnetic storms? O gradual build-up?
• Are the global sawtooth oscillations global
  dipolarizations Skoug, Borovsky,..?
• MODELERS ENA simulation code available.