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Stan Solomon, Wenbin Wang, and Mike Wiltberger High Altitude Observatory

Simulation of Neutral Wind Feedback Effect on the Magnetosphere/Ionosphere System during Geomagnetic Disturbances. Stan Solomon, Wenbin Wang, and Mike Wiltberger High Altitude Observatory National Center for Atmospheric Research.

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Stan Solomon, Wenbin Wang, and Mike Wiltberger High Altitude Observatory

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  1. Simulation of Neutral Wind Feedback Effect on the Magnetosphere/Ionosphere System during Geomagnetic Disturbances Stan Solomon, Wenbin Wang, and Mike Wiltberger High Altitude Observatory National Center for Atmospheric Research CISM Advisory Council Meeting • Boston University • 23 February 2006

  2. Review of Neutral Wind Electrodynamic Effect Calculations • Killeen and Roble [1984] used the TGCM to find that neutral winds can be driven to follow the ion convection pattern by ion drag forcing. • Forbes and Harel [1989] modified the RCM and TGCM to include the “effective winds” and found that these winds had a relatively small effect on the system, but lacked a fully coupled ionospheric model. • Deng et al. [1993] used the TIGCM to study the neutral wind “flywheel” effect and determine that it can make significant contributions to the FAC system during northward IMF conditions after a geomagnetic storm. • Peymirat et al. [2002] used the MTIE-GCM to determine that the influence of neutral winds is limited to the auroral zone and the produces a ~10% change in potential and a 20% reduction in inner magnetospheric pressure. • • Ridley et al. [2003] found similar results by coupling the TIE-GCM with the BATS-R-US global MHD model of the magnetosphere (but without conductance feedback).

  3. Coupled Magnetosphere-Ionosphere-Thermosphere Model LFM Jll, np,Tp E Magnetosphere - Ionosphere Coupler (H+P)=Jll-Jw Particle precipitation: Fe, E0 Conductivities: p, h, Winds: Jw Electric Potential: tot TING

  4. The Neutral-Wind Driven Field-Aligned Current “Jw” Ion Drifts & p (mho) Neutral Winds & Temps (K) Jw (A/m2) Where: I is the magnetic field inclination angle B is the magnetic field vector b is the magnetic field unit vector z1 and z2 are min and max model altitudes p and h are the Pedersen and Hall conductivities U is the neutral wind velocity

  5. Animation of CMIT Model Test Run

  6. Animation of Ionosphere/Thermosphere Response

  7. Animation of Neutral-Wind Driven Field-Aligned Current “Jw”

  8. Effect of Neutral Wind Feedback on Potential and FAC

  9. “Flywheel” Effect after Northward Turning of Bz

  10. Discussion • This experiment demonstrates that the model methodology appears to be working, but may be somewhat unrealistic in terms of the solar wind forcing. • We will now repeat these calculations using measured solar wind inputs during selected events to investigate the magnitude and morphology of the neutral wind feedback effects. • These effects are not particularly large or significant. • The full simulation of atmospheric response does enable us to calculate the transfer of solar wind energy into the thermosphere and its disposition as advective, heating, and ultimately radiation.

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