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

HENA: IMPLICATIONS FOR STRONG E-FEILDS (and some more...). P. C:son Brandt, D. G. Mitchell, R. Demajistre, E. C. Roelof The Johns Hopkins University Applied Physics Laboratory. OUTLINE. E-FIELD DURING MAINPHASES 1. Storm mainphases: HENA observes peak at post-midnight.

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

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  1. HENA: IMPLICATIONS FOR STRONG E-FEILDS(and some more...) P. C:son Brandt, D. G. Mitchell, R. Demajistre, E. C. Roelof The Johns Hopkins University Applied Physics Laboratory

  2. 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]

  3. 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.

  4. WHY NOT SKEWING?

  5. 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.

  6. 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?

  7. 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.

  8. 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.

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