coupling between magnetospheric and auroral ionospheric scales during space weather events
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
07/11/2007
ESSW4, Brussels 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
07/11/2007
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
07/11/2007
ESSW4, Brussels 3
Auroral activity and space weather events
Image courtesy of LESIA, Meudon, Paris
07/11/2007
ESSW4, Brussels 4
Auroral activity and space weather events
Close to solar maximum (May 1998)
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ESSW4, Brussels 5
Auroral activity and space weather events
At solar minimum (September 2007)
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ESSW4, Brussels 6
Dayside auroral arcs and coupling to magnetospheric boundary layers and SW
properties
Credit: sci.esa.int/cluster
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ESSW4, Brussels 7
Dayside auroral arcs and coupling to magnetospheric boundary layers and SW
properties
Newell et al., 2004
Moen et al., 1994
Vo and Murphree, 2001
07/11/2007
ESSW4, Brussels 9
Tangential discontinuities with sheared flows as auroral generators
Planar surface in the y-z planeVariations 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
07/11/2007
ESSW4, Brussels 10
Tangential discontinuities with sheared flows as auroral generators
•piecewise Maxwellian VDFs (Roth et al., 1996) •analytical moments 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
07/11/2007
ESSW4, Brussels 11
Current continuity in the ionosphere; feedback effects
•Current continuity in the ionosphere:
mhos)}sJm({106.15.0 2/11-2-2 p
•Ionospheric feedback:
)(),(IIi
ip
ip
imii xx
Ix
xj
•Self-consistent m; ad-hoc models in previous studies (Lyons, 1980, 1981)
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ESSW4, Brussels 12
Quasi-static coupling model: numerical results
07/11/2007
ESSW4, Brussels 13
Quasi-static coupling model: numerical results – effects of LLBL/SW speed
mhos)}sJm({106.15.0 2/11-2-2 p
•Solid line : non-uniform P with P0=0.5 S•Dashed line : non-uniform P with P0=5.0 S•Dotted line : uniform P=P0=5.0 S
and feedback
07/11/2007
ESSW4, Brussels 14
Quasi-static coupling model: numerical results – effects of LLBL/SW density
mhos)}sJm({106.15.0 2/11-2-2 p
•Solid line : non-uniform P with P0=0.5 S•Dashed line : non-uniform P with P0=5.0 S•Dotted line : uniform P=P0=5.0 S
and feedback
07/11/2007
ESSW4, Brussels 15
Quasi-static coupling model: numerical results – effects of e- temperature
mhos)}sJm({106.15.0 2/11-2-2 p
•Solid line : non-uniform P with P0=0.5 S•Dashed line : non-uniform P with P0=5.0 S•Dotted line : uniform P=P0=5.0 S
and feedback
07/11/2007
ESSW4, Brussels 16
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 differenceenergy flux
•Low P0 thinner structuressmaller energy flux