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Coupling between magnetospheric and auroral ionospheric scales during space weather events

Coupling between magnetospheric and auroral ionospheric scales during space weather events. M. ECHIM (1,2), M. ROTH(1) and J. DE KEYSER(1) (1) Belgian Institute for Space Aeronomy, Brussels, Belgium (2) Institute for Space Sciences, Bucharest, Romania. Outline of the talk.

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Coupling between magnetospheric and auroral ionospheric scales during space weather events

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  1. Coupling between magnetospheric and auroral ionospheric scales during space weather events M. ECHIM (1,2), M. ROTH(1) and J. DE KEYSER(1) (1) Belgian Institute for Space Aeronomy, Brussels, Belgium (2) Institute for Space Sciences, Bucharest, Romania ESSW4, Brussels

  2. Outline of the talk • Auroral activity and space weather events • Dayside auroral arcs and coupling to magnetospheric boundary layers and SW properties • Tangential discontinuities with sheared flows as auroral generators; typical scales • Current continuity in the ionosphere; feedback effects • Quasi-static coupling model: numerical results • Conclusions, future research ESSW4, Brussels

  3. Auroral activity and space weather events Image courtesy of LESIA, Meudon, Paris ESSW4, Brussels

  4. Auroral activity and space weather events Close to solar maximum (May 1998) ESSW4, Brussels

  5. Auroral activity and space weather events At solar minimum (September 2007) ESSW4, Brussels

  6. Dayside auroral arcs and coupling to magnetospheric boundary layers and SW properties Credit: sci.esa.int/cluster ESSW4, Brussels

  7. Dayside auroral arcs and coupling to magnetospheric boundary layers and SW properties Newell et al., 2004 Vo and Murphree, 2001 Moen et al., 1994 ESSW4, Brussels

  8. Tangential discontinuities with sheared flows as auroral generators Planar surface in the y-z plane Variations along the xm coordinate normal to the TD plane. E along the x-axis, B along the z-axis, a,V and J along the y-axis ESSW4, Brussels

  9. Tangential discontinuities with sheared flows as auroral generators • piecewise Maxwellian VDFs (Roth et al., 1996) • analyticalmoments of the VDF • Φm and a computed numerically from the Maxwell’s equations • The model can describe simultaneous shears in B and V flow • Convergent electric field ESSW4, Brussels

  10. Current continuity in the ionosphere; feedback effects • Current continuity in the ionosphere: • Ionospheric feedback: • Self-consistent Fm; ad-hoc models in previous studies (Lyons, 1980, 1981) ESSW4, Brussels

  11. Quasi-static coupling model: numerical results ESSW4, Brussels

  12. Quasi-static coupling model: numerical results – effects of LLBL/SW speed and feedback • Solid line : non-uniform SP with SP0=0.5 S • Dashed line : non-uniform SP with SP0=5.0 S • Dotted line : uniform SP=SP0=5.0 S ESSW4, Brussels

  13. Quasi-static coupling model: numerical results – effects of LLBL/SW density and feedback • Solid line : non-uniform SP with SP0=0.5 S • Dashed line : non-uniform SP with SP0=5.0 S • Dotted line : uniform SP=SP0=5.0 S ESSW4, Brussels

  14. Quasi-static coupling model: numerical results – effects of e- temperature and feedback • Solid line : non-uniform SP with SP0=0.5 S • Dashed line : non-uniform SP with SP0=5.0 S • Dotted line : uniform SP=SP0=5.0 S ESSW4, Brussels

  15. Summary, Conclusions • Larger SW/LLBL velocity larger shear more power • Increased luminosity of the auroral arc • Larger SW/LLBL density thinner auroral structures • Ionospheric feedback Larger potential difference • energy flux • Low SP0 thinner structures • smaller energy flux ESSW4, Brussels

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