The Role of Ionosphere in Ring Current Development During the Super Storm in November 2003

1. The Role of Ionosphere in Ring Current Development During the Super Storm in November 2003 Mei-Ching Fok1, Thomas E. Moore1, Dominique C. Delcourt2, Steven P. Slinker3 Joel A. Fedder4, Yusuke Ebihara5, and Samuel T. Jones6 1NASA Goddard Space Flight Center, USA 2CETP-CNRS-IPSL, Saint-Maur des Fosse, France 3Naval Research Laboratory, USA 4Leading Edge Technology, Inc., USA 5Nagoya University, Japan 6University of Texas in Arlington, USA ST11-A0009 August 2, 2007 2007 AOGS Meeting, Bangkok, Thailand

2. Outline • The super storm in November 2003 • Lyon-Fedder-Mobarry (LFM) global magnetospheric simulation of the Nov03 storm • Modeling the polar wind and auroral wind (O+) outflow from the ionosphere during the Nov03 storm • Modeling the ring current development during the Nov03 storm with solar, polar and auroral sources • Effect of ionospheric conductivity on ring current development

3. November 2003 Storm Solar wind velocity • Solar wind velocity increased to ~750km/s. Solar wind density • Solar wind density was unusually high IMF Bz • IMF Bz decreased to -50 nT. • Negative IMF Bz lasted for ~ 12 hours. Dst • Dst reached -472 nT.

4. LFM Simulation of the November 2003 Storm

5. Ionospheric Outflow Driven by MHD Condition

6. Ionospheric Outflow Driven by MHD Condition

7. Simulation of Auroral Wind and Polar Wind Outflow O+ Strong non-adiabatic acceleration Violation of 1st adiabatic invariant Test-particle code of Delcourt

8. Calculation of Density and Temperature from Test-Particle Trajectories The entire simulation space is divided into bins of 1 RE3 volume.

9. The Comprehensive Ring Current Model (CRCM) Boundary Condition Solar, Polar, Auroral Winds Ring Current Phase Space Density Charge Exchange Drift Losses LFM Magnetic Field Magnetospheric Electric Field Field Aligned Current Ionospheric Electric Field Ionospheric Conductivity Cross Polar Cap Potential Drop

10. Ring Current Formed by Solar Wind Ions

11. Ring Current Formed by Auroral O+ Ions

12. Ionospheric Particles Contribution to Ring Current Energy Content Ionospheric ion outflow contributes significantly to the ring current particle and energy content during this event.

13. Simulated ionospheric Potential Auroral conductivity includes effects due to precipitating electrons and field-aligned potential drop

14. Effect of Ionospheric Conductivity on Electric Potential LFM Auroral Conductivity Hardy Auroral Conductivity Strong field at sharp conductivity gradient

15. Effect of Ionospheric Conductivity on Ring Current Development LFM Auroral Conductivity Hardy Auroral Conductivity Relatively strong pressure in the post-midnight sector due to high auroral conductivity.

16. Summary • The global magnetospheric configuration and ring current development during the storm on 20-21 November 2003 are simulated using the combined tool: LFM + Delcourt-particle-code + CRCM • Particles from solar wind (H+), auroral wind (O+) and polar wind (H+) are considered as sources of ring current ions. • Auroral wind and polar wind outflow characteristics are driven by instantaneous MHD conditions at the ionosphere. • Contribution of auroral O+ to the ring current is comparable or higher than that of the solar wind source. Contribution from the polar wind is negligible. • Strong auroral conductivity and sharp gradient produce high ring current flux in the post-midnight sector.